5 Evaluation Scales in Neurocritically Ill Patients

Jose M Dominguez-Roldan ¹, Walter Videtta ², Claudio Garcia Alfaro ¹, Juana Maria Barrera Chacon ¹, Modesto Romero Lopez ²

¹ Hospital Universitario Virgen del Rocio de Sevilla, Spain

² Universidad de Huelva, Spain

5.1 Objectives

Accurate assessment of the clinical condition of critically ill neurological patients is an essential part of intensive care. The application of clinical rating scales and the evaluation of their results have become common practice for health professionals caring for severely ill neurological patients. Evaluation scales serve different purposes. Understanding their implications is essential for communication between professionals from different areas and institutions. This chapter describes and discusses the most frequently used scales in assessing acute and subacute critical neurological patients.

5.2 Introduction

The usefulness of clinical rating scales and outcome is manifold. Comparison between different series of patients is possible. Some scales are clinical, others are based on images, and others still use a combination of different variables. Scales may be useful for classifying patients, establishing prognosis, helping in decision making. For example, the Fisher scale is used specifically to assess the risk of vasospasm in patients with spontaneous subarachnoid hemorrhage (SAH). In patients with traumatic brain injury (TBI), a score on the Glasgow Coma Scale (GCS) <9, GCS=9-12, GCS=14-15 will reflect severe, moderate, or mild illness, respectively. This has implications for decision making: patients with severe TBI and a GCS ≤8 must be intubated and mechanical ventilation initiated. Some of the scales are specific to certain diseases and seek to assess their clinical aspects. In contrast, other scales are more generic and are applicable not only for evaluating different diseases but also different stages of neurological processes. For example the GCS, which was initially devised for assessing patients with TBI, has been extended to include other pathologies such as neurological damage of vascular origin.

5.3 Evaluation in the Acute Phase

5.3.1 Clinical Scales for the Evaluation of Altered Consciousness

Assessment schemes for the evaluation of consciousness disorders provide quantitative measures of the severity of coma in the acute phase and have proved useful in studies predicting functional sequelae after hospital discharge. The development of coma scales continued in response to the need for reliable, standardized data that could inform safe therapeutic measures and facilitate the design of protocols for clinical performance. Point scales serve to: 1) standardize levels of awareness in clinical research, thus allowing their comparison and replication across studies; 2) monitor the clinical course of the disease; 3) facilitate performance and decision making; and 4) predict outcome.

One advantage of coma scales is that they allow statistical analysis of the data for testing their reliability, validity and clinical significance. One drawback of point scales is that each measure is based on the clinician’s experience, knowledge and observation. The ideal coma scale should meet the requirements of: 1) high validity; 2) classification of severity; 3) reliability; 4) linearity (additivity and homogeneity); 5) association with disease outcome; 6) ease of application; 7) simplicity; 8) yield; and 9) minimum redundancy.

Even with the use of these scales, however, the assessment of coma is not without controversy. Different scales have been designed to improve the GCS. For example, the Glasgow-Liège Scale evaluates indicators of brainstem function.

Other requirements of any assessment tool are that the scale items are representative of each construct, are clearly observable, and have a clear clinical interpretation. From the assumption that normal consciousness and coma constitute two ends on a continuum of human brain functional states and that consciousness involves two distinct but related attributes (alertness and content), some degree of caution is necessary when evaluating responsiveness since any response will need to be set somewhere along this continuum. From this, we can infer that, depending on the alterations in central nervous system (CNS) function, a scale will have different answers that may correspond to some alteration of consciousness. Since alertness and monitoring overlap, identifying specific indicators for exclusive categories in scale design is difficult. The result is the conceptualization of alertness and vigilance variables as one entity. In addition to indicators of neurological functions, other variables in medical and neurological examination seek to capture aspects of the etiology and diagnosis of coma motor responses, such as pupillary size and reactivity and ocular motility.

In reality what we actually see, however, are the pathophysiological and neuroanatomical correlates that provide a reliable localization and characterization of the illness. The responses to each item are organized hierarchically on a continuum from normal responses to a progressive impairment of brain function that ends in brain stem reflex movements or even their absence.

The higher functions (contents of consciousness) refer to a wide range of human behavioural characteristics such as cognitive, emotional, and sensory perception, motor functions, etc.).

Glasgow Coma Scale

The Glasgow Coma Scale (GCS) is widely used for assessing the level of consciousness in patients with neurological disorders of diverse etiology. Originally developed by Jennett and Tesdale and published in 1974, it measures the level of consciousness in TBI patients. Although the original scale had a maximum score of 14 points, with subsequent refinements the authors expanded the section on the assessment of motor response to 6 points (initially consisting of a maximum of 5 points). The descriptors currently included in the GCS evaluate: 1) motor activity; 2) verbal response; and 3) eye opening (Table 5.1).

Table 5.1. Glasgow Coma Scale (GCS).

The total score is the sum of the points assigned for each activity examined (range, 3-15). The severity of head injury can be established by scoring sections. There is also consensus that a patient with a GCS score <9 will have a level of consciousness that can be considered as “coma”. A description of the scale scoring system is given below.

Eye opening: 4 points are assigned for spontaneous eye opening; these patients still have eye fixation and eye tracking, although it is not necessary to consider the existence of eye opening. The presence of eye opening and staring suggests an intact optic pathway and visual cortex; 3 points are recorded if the patient opens his eyes in response to a verbal command. This usually occurs in patients with drowsiness who respond to an auditory stimulus to open their eyes. A score of 2 points is recorded when the patient opens his/her eyes only in response to painful stimuli. These states are compatible with more severe brain dysfunction. A score of 1 is recorded when there is no eye opening in response to various intense stimuli.

Motor response: this is the most important section of the GCS from which the level of stimulus processing at the neuraxis can be inferred more accurately. Clinical examination of motor response in certain patients can be likened to an examination by somaesthetic evoked potentials. The integrated motor responses within the GCS (GCSm) may suggest the highest level of neural signal processing in patients with acquired acute brain damage.

On stimulation, the limb should be brought to cross the midline. Alternatively, if the upper limb has been placed on the root of the lower limb and the stimulus is applied to the upper chest, the hand will be elevated above the umbilical line. The score reflects an intact cortex and cortical pathways but is associated with brain dysfunction within a hemisphere. When there is a simple withdrawal response to pain or a stereotyped or classifiable response, 4 points are assigned, which should suggest cortico-subcortical location as the highest level of neurological processing. It should be remembered that to establish that the patient actually performs a “withdrawal response” the browser should monitor the elbow movement. Accordingly, a response is considered as “withdrawn” if the elbow is away from the axis of the body, regardless of whether that movement is associated with a forearm flexion. The typical response in flexion (bending or decortication) (rated with 3 points) is a motor response to noxious stimuli. It should be noted that decorticate flexion of the elbow involves the approach toward the major axis of the body associated with a forearm and often bending flexion of the wrist. This type of response is often observed in subacute neurological processes of vascular origin not common in traumatic events. A motor response is assigned 2 points if, after nociceptive stimulation, the patient performs a pronoextension extensor response of the upper limb, from which it can be inferred that the highest level of processing does not exceed the mesencephalic level. A score of 1 is recorded for the absence of motor response to painful stimuli; this indicates very severe bilateral hemispheric involvement or brainstem damage. Elicitation of the verbal response in intubated patients should not be limited to a repertoire of three questions that explore temporo-spatial orientation: “What is your name?”, “Where are you?” and “What year is it?”. If the patient speaks in an oriented and conversant manner, the maximum score of 5 is recorded, 4 points will be given when the patient is disoriented and conversant, 3 points when words are inappropriate (intelligible but inappropriate to the situation); 2 points for unintelligible sounds, and 1 point for no verbal response.

The GCS measures the degree of neurological dysfunction as a global function of “consciousness” at the time of examination. However, its prognostic value in TBI and other acute neurological processes mainly relates to the score after all extracranial factors that can influence the level of consciousness have been controlled. The effect that certain factors may have on the level of consciousness is well known. Hypotension, hypoxia, sedative drugs, toxic or postcritical state can all influence the GCS score. The GCS, which may be called “Score Collection Glasgow”, or first aid, has the same prognostic ability as the Glasgow score obtained once these factors have been controlled.

Notes for Using the Glasgow Coma Scale

As initially described, the GCS was, and retains its main indication in the evaluation of decreased level of consciousness in patients in the acute phase of TBI. The ubiquity of the scale has facilitated its spread to other groups of severe neurological processes of diverse etiology such as ischemic or hemorrhagic cerebrovascular accidents, CNS infections, or acute complications of intracranial neoplasms. It is also often applied in other circumstances for evaluating only functional alterations of cerebral metabolism or causes of a systemic nature, coma, renal failure, hepatic, pulmonary, metabolic diseases, in the context of septic shock. It is also useful in cases of alcohol intoxication or drug abuse.

The GCS has also been combined with other scales to assess acute and severe neurological conditions. Thus, in evaluating patients with spontaneous SAH, the GCS has been included in one of the major scales assessing its severity, the scale of the World Federation of Neurosurgeons.

Limitations of the Glasgow Coma Scale

There are some limitations to the implementation of the GCS. For example, neurological disorders not directly altering the level of consciousness may interfere with the examination: for instance, aphasia, sensory deficits such as deafness or blindness, psychiatric disorders, and mental deficit can all add to the difficulty of the clinical examination.

The verbal component of the GCS may be precluded in intubated patients. In such cases, the verbal component can be removed from the scale, and an “I” (intubated) noted on the evaluation form, without assessing this parameter, or otherwise make inferences from other responses. Hence, eye opening in response to verbal commands and pain is assigned an overall score of 12 points, while the total GCS score is 7 points for eye opening in response to pain and stereotyped flexing of the extremities.

Another possible limitation to the GCS is the fact that the motor component may also present difficulties in evaluation due to the presence of immobilizing splints or traction for the treatment of orthopedic injuries. Other difficulties in motor evaluation include motor deficits, such as pyramidal tract lesions or intracerebral lesions which do not affect consciousness but can alter the motor response. So it is not uncommon to find patients with motor responses resulting from diffuse axonal injury type which interfere with the evaluation of consciousness according to the GCS. You can see how some patients with axonal injury similar to pronoextension objectified in the responses of decortication, but with a different meaning. In the case of decerebrate bending, a mechanism involved in the genesis of motor response is the cessation of the connection between the cerebral cortex and the reticular substance due to an acute hemispheric process that intercepts the control and inhibition of intrinsic muscle tone and the substance, manifested by an abnormal motor response. In contrast, in patients with diffuse axonal injury and pronoextension these responses often manifest as spontaneous activity due to diencephalic substance that directly stimulates the brainstem internuncial neurons, generating pronoextension responses. Such situations and others like them must be taken into account when assessing the state of consciousness in patients with axonal injury. Only then can a judicious interpretation be made of the meaning of this type of response.

The ocular component of the GCS may be difficult to assess in patients with facial trauma in which the upper third of the facial mass is seriously injured or eyelid edema occludes the eyelids and makes eye opening impossible, or also in patients presenting with congenital or acquired amaurosis, as well. In such cases, consideration should be given to the component of eye opening; assessment of the level of consciousness will have a maximum total of 11 points, including verbal and motor response.

In any case, it should be noted that of the three sections composing the GCS, the motor component has the highest profile and greatest weight in the evaluation of global CNS dysfunction. For some authors, the motor component of the GCS itself contains all the necessary information even in cases suggesting that, given the prognostic capacity of this section, it would replace the entirety of the scale in predicting the evolution of TBI patients

Training in the application of the GCS is key to increasing its reliability. Its application by a well-trained staff ensures adequate reliability, although major disagreements have been described: one series reported that between 20 and 35% of patients evaluated were rated differently and by different evaluators. It is therefore important not only to adequately train the examiners but also harmonize interpretation of the responses and the intensity and characteristics of the stimuli applies to the patient.

Although the GCS has a capacity of major global prediction when analyzing large series of patients, it should not be used in predicting the prognosis of specific individuals with critical neurological process such as TBI. In fact, we find patients with very low scores due to the development of acute extra-axial lesions, extradural hematoma, who, when treated quickly and the masses are evacuated, will have a good long-term prognosis. Consequently, the ability to forecast the GCS should be used primarily in the study of patient groups.

Innsbruck Coma Scale

Like the GCS, the Innsbruck Coma Scale (ICS) was developed to evaluate TBI patients. The ICS is a summative scale; scores range from 0 to 23 points, with a minimum score of 0 (no response) and a maximum of 23 (patient oriented). The scale takes the same values (Table 5.2) as the GCS for ocular and motor responses, in addition to eye position, pupil size, pupil response to light, and oral automatisms. In the lower ranges of scores in the evaluation of the patient on admission, the ICS is highly predictive of patient mortality at 21 days of stay.

Table 5.2. Innsbruck Coma Scale (ICS).

Edinburgh Coma Scale-2

The Edinburgh Coma Scale-2 (E2CS) is the best answer as long as the patient is considered valid to classify according to an ordinal system, where a higher score indicates lower level of consciousness. The system assigns a single score in a continuous exploration from a lack of any response to the responses of patient orientation. It has the advantage over previous scales that it does not add co-variable factors. Its shows good correlation with the GCS and the Glasgow Outcome Scale (GOS) for mortality and morbidity levels organized in a proper order. For 1 to 3, the ratio increases rapidly for morbidity, but mortality is <30% for a score of 5, then non-linear up to 100% with a score of 10. A drawback to the E2CS is that it assumes that in patients obeying orders the verbal response is preserved in the absence of obtaining the same or the wrong answer. Another drawback is that an intubated patient cannot be expected to give a verbal response, unless, perhaps a response is elicited and a lower score assigned. The scale takes the values specified in Table 5.3.

Table 5.3. Edinburgh-2 Scale (E2CS).

Other Scales

The Glasgow Coma Scale-Liège (Born, 1988), designed on the GCS, is based on the fact that, in the first 24 hours after brain injury, the study of the brainstem reflexes index provides a good prognosis and that early mortality rates are associated with brainstem reflex disorders (Table 5.4).

The Reaction Level Scale (RLS85) (Table 5.5) is another scale that assesses the level of response in patients with acute brain injury. It was developed for use in instances where evaluation can be problematic, as in intubated patients or patients with eye swelling. The scale has a good reliability for various etiologies of brain injury such as head trauma and stroke. The main assumption in the scale’s design is that there is a continuum in the level of consciousness, alertness and orientation to non-response to noxious stimulation. Similarly, it is assumed that the reverse sequence must occur in the patient with impaired recovery of consciousness. Based on theoretical considerations and clinics, each change in degree on the scale can be considered a reflection of a real change in the patient’s condition. It is also assumed valid to consider the best response of the patient. The scale has 8 categories of bedside assessment.

Table 5.4. Glasgow Liege Scale (GLS).

Table 5.5. Reaction Level Scale (RLS85).

5.3.2 Hunt and Hess Scale

Based on the classification of Botterell and Lougheed, the Hunt and Hess scale was published in 1968 and has been several subsequently amended. It was initially designed to determine the risk of surgery that a ruptured aneurysm and timing of surgery carry. Although several factors such as age and number of days elapsed since bleeding are involved, WE Hunt and RM Hess estimated that the intensity of meningeal inflammation, the severity of neurological deficit, and the presence or absence of neurological disease were clinical data that were better able to predict surgical risk. The scale was derived from the data on 275 consecutive patients and surgical intervention, either early (in patients with grades I and II), or delayed (reserved for patients with grade III or higher awaiting neurological improvement). Neither patient age nor aneurysm location were determinants of surgical risk. The number of days since bleeding was not considered an important prognostic element.

The Hunt and Hess classification is structured on 5 grades depending on the level of intensity of clinical manifestations such as headache, stiff neck, focal neurologic deficit or altered level of consciousness (Table 5.6). The first 2 grades include patients without altered consciousness or stiff neck graded as minimal to moderate while headache can be graded mild or moderate to severe. Such patients have no focal deficits but may have paralysis resulting from cranial nerve compression due to aneurysmal growth. Grade I and II patients were submitted to early surgery in the Hunt and Hess series.

Table 5.6. Hunt and Hess Scale.

Indications for the Use of the Hunt and Hess Scale

The principal indication for the Hunt and Hess scale is to predict surgical-risk patients with recent subarachnoid hemorrhage (SAH). According to initial studies, an increase in the clinical grade is associated with an increased risk of mortality. However, this scale was developed before the implementation of navigation techniques or endovascular coiling. Therefore, the recommendation that aneurysm exclusion techniques should be limited to Hunt and Hess <grade III have become obsolete, owing to the significantly lower risk for patient undergoing an endovascular technique. Although not intended for this purpose, the scale has been frequently used to assess the overall clinical risk of SAH. However, new scales may be more accurate in predicting surgical risk.

Limitations of the Hunt and Hess Scale

As discussed above, the Hunt and Hess scale was not intended as a predictor of the clinical course of patients with spontaneous SAH, although it often has been used for such purposes.

The Hunt and Hess scale should be used judiciously in those patients in whom the level of consciousness may be affected not only by the bleeding but also by its accompanying complications. It’s not uncommon to see patients with SAH and spontaneous seizures in whom the level of consciousness during and after the seizures is influenced by the epileptic activity and not by a decreased level of consciousness produced directly by bleeding. The development of hydrocephalus, which progress over time, also significantly influences the level of consciousness, without implying a worsening of prognosis derived directly from SAH but indirectly from hydrocephalus. After placement of a cerebrospinal fluid shunt, consciousness returns to the previous level in relation to the SAH. That “restored” level of consciousness should be the one that really establishes the clinical prognosis.

Certain symptoms such as stiff neck or headache pain, for example, have a subjective component. Probably it is the subjectivity of both the physician and the patient in the interpretation of certain symptoms included on the Hunt and Hess scale that justifies in part the further development of other scales such as the World Federation of Neurological Surgeons (WFNS), with its more quantitative measurements that were introduced to overcome the problem of interobserver variability in the interpretation of certain signs and symptoms.

5.3.3 World Federation of Neurological Surgeons Scale

This scale was introduced in 1988 in an attempt to have a simple scale that could estimate the prognosis of a patient with SAH and could be used as a means to quantify changes in the patient’s clinical status throughout the acute phase. The scale needed to be reliable and, above all, allow its combination with other methods of clinical evaluation of SAH, which until then had been developed along the lines of Hunt and Hess for the Cooperative study.

The WFNS Scale was developed on the basis of the GCS. Unlike the Hunt and Hess scale, it does not take into consideration the presence of signs such as stiff neck or symptoms such as headache. The Surgeons Committee had to choose at the outset between the proposed Kassell and Torner stratification (5 grades) and that of Jagger et al. (7 grades) of spontaneous SAH, agreeing finally on the scheme presented in Table 5.7.

Table 5.7. World Federation of Neurological Surgeons scale.

As can be seen from the table, set up in 5 grades, an unruptured aneurysm was considered as one grade, the GCS was taken for assessing level of consciousness, given the scale’s widespread application in the evaluation of head injury, and was used only for high-grade focal deficits (aphasia, hemiparesis, and hemiplegia), which differ in grades II and III on this scale.

Special attention should be drawn to the fact that ptosis and ocular adduction difficulty (third cranial nerve palsy or oculomotor internal) are not considered suggestive of focal data but instead the result of direct compression of the third cranial nerve due to the growth of the aneurysm in the posterior circulation, thus keeping the patient in group II on the WFNS scale. The WFNS scale provides some advantages over the Hunt and Hess scale, such as greater simplicity and lower interobserver variability.

The WFNS scale was later modified by Sano and Tamura to improve the discriminatory power of each grade. With this modification, the WFNS scale was restructured into 6 grades by subdividing grade III and redefining grades I and II. In this new scheme, patients with a GCS score of 15 and neurologically intact are categorized in grade I, although some may have cranial nerve palsies that do not involve increasing severity (as in third nerve palsy secondary to the sudden growth of aneurysms of the posterior communicating arteries). Grade II patients, including those with a GCS score of 15, have a clinically intense headache and/or stiff neck. Grade III, (GCS score 13-14) is divided into two subgroups: IIIA if no focal deficit and IIIB if focal deficit is present. In grade IV (GCS score 7-12), the upper and lower scores coincide with the WFNS scale, without changing the GCS score for patients with sufficient consciousness but may lose the swallow reflex and so will require admission to the ICU. Finally, grade V (GCS score <7) includes patients in deep coma with abnormal motor reactions.

Indications for Use and Limitations of the WFNS Scale

The WFNS scale should be used for the evaluation of the clinical severity of patients with spontaneous SAH during the acute phase. The WFNS clinical scale is now better able to establish the prognosis of patients after neurological examination in the acute period of SAH.

Possible limitations of the WFNS scale are: 1) absence of clinical significance in the scale because highly symptomatic patients with severe headache and severe neck stiffness, who are nevertheless classified as grade I, may not have altered level of consciousness or motor deficits; 2) assessment of the level of awareness is important for the prediction of death and disability; however, the presence of focal signs such as hemiplegia, hemiparesis and/or aphasia is important in the development of disabilities ensuing from acute neurological process, making it less reliable in predicting mortality; 3) detected inconsistencies in the cut-off scores on the GCS to differentiate between grade II and III and IV characteristic of these groups because they have the same neurological status with the only difference being the focus. Group IV has a much broader neurological status comprising a GCS score of 7 and a GCS score 12 which denotes a confused state; 4) adds defects attributable to the GCS. Thus, it is advisable to collect individual components of the GCS (eye, motor and verbal responses) as the same overall score; the different prognoses will depend on the score of each of the three components.

5.3.4 The Johns Hopkins Classification

One of the more recently developed scales for the assessment of patients with spontaneous SAH is the Johns Hopkins classification published by Tamargo R et al. in 1997 (Table 5.8) and proposed as an alternative to the two most commonly used scales hitherto, Hunt and Hess and WFNS.

Table 5.8. Johns Hopkins scale.

Based on the GCS, and like the WFNS scale, it attempts to discern the severity within the group of patients with grade IV SAH on the WFNS scale. On the latter, grade IV is made up of patients with severe coma, a score of 6, and others with much less involvement (score of 12) that only have a certain degree of drowsiness. In contrast, the Johns Hopkins scale segregates patients with a GCS score of 6 to 8 (grade IV) from those with a score <6 (grade V).

The Johns Hopkins scale solves the problem of classification of patients with very different prognoses within the same group, and differentiating between mild, moderate and severe illness, compared with the lack of resolution that the WFNS scale has. Although the scale has not been evaluated in large series, it is remarkable for its simplicity and ease of use by clinicians.

The indications for its use are similar to those mentioned for the WFNS scale, i.e., evaluation of the severity and clinical impact of SAH bleeding. Like all scales, including the GCS, there are limitations to its use.

5.4 Imaging-based Assessment Scales

5.4.1 Traumatic Coma Data Bank Scale

The Traumatic Coma Data Bank (TCDB) scale is currently the most widespread tool in the evaluation of computed tomography (CT) of TBI. The scale was presented in 1991 by Marshall, et al. and was initially developed to evaluate through CT images in the acute phase of patients with head injury, intracranial lesions in these patients. The classification is intended to include the universe of all patients with closed head injuries and classify them according to prognostic features and therapeutic orientations. The initial justification for the development of the scale was twofold: to establish subgroups of patients with head trauma who have a similar risk of neurological impairment, and to identify groups of trauma patients with similar clinical medium and long-term prognosis. The scale was developed exclusively for blunt trauma, excluding injuries caused by firearms, and was initially implemented only for patients with severe head trauma, i.e., with a GCS ≤8. It has a direct relationship with the level of consciousness disorder as assessed by GCS, specifically the GCSm and different categories of the TCDB classification. Likewise, the various levels of this classification scheme are associated with mortality rates significantly different from each other. According to CT findings, the diagnostic classification includes six categories, four of which pertain to predominantly diffuse lesions and predominantly focal injuries. Diffuse lesions (types I to IV) may include low-volume mass lesions (limit, 25 cc), but with diffuse brain injury as a predominant lesion. Also considered for this classification in addition to the mass lesion volume are: midline shift (more or less than 5 mm) and compression of mesencephalic cisterns. One advantage of the TCDB scale is its widespread use in centres caring for TBI patients. Besides its clinical applicability, another factor contributing to its dissemination is that there is a high correlation between CT scan readers when analyzing the images in trauma patients. This degree of agreement is higher when there are mass lesions and when lesions are classifiable as diffuse brain injury (grades I to IV). Table 5.9 presents the different categories of the TCDB classification.

Table 5.9. The Traumatic Coma Data Bank (TCDB) scale.

As mentioned above, the different categories are associated with different rates of mortality; the mechanism most probably involved is the presence of intracranial hypertension. Thus, mortality increases progressively in the different categories of diffuse injury, reaching a mortality of 56% in type IV diffuse lesions, comparable to the mortality of injured patients with evacuated masses (53%). In grade III and IV diffuse injury, the most important predictor of evolution is the intracranial pressure, whereas in the other age groups, the GCS and pupil reactivity predict the prognosis better. It is therefore evident that the TCDB classification informs us of the likelihood of intracranial hypertension and mortality; however, there are many other factors such as patient age, previous trauma, and comorbidities which also have a role in the outcome.

Indications for Use and Limitations of the Traumatic Coma Data Bank Scale

The TCDB scale should be used for estimating the risk of death and intracranial hypertension in patients who have suffered a head injury. It was designed to be applied to the first CT scan obtained during the acute phase of injury, since the TCDB classification includes only primary traumatic injuries. On the other hand, although the scheme was developed for evaluating patients with severe head trauma, i.e., with a GCS score ≤8, its use has been extended to other groups of TBI patients (moderate and mild) to describe intracranial lesions. Moreover, although the TCDB scale was not designed for that purpose, certain categories in the scheme are associated with certain therapeutic or monitoring procedures. Thus, the presence of type III diffuse injury is associated with the presence of intracranial hypertension, and linked to intracranial pressure monitoring. Similarly, the presence of space-occupying lesions (<25 cm³) requires a surgical therapeutic approach, which undertaken or not, leads to a reclassification of the patient within the TCDB classification.

It should be noted that the TCDB classification is a dynamic rating system; therefore, given the possibility of development of traumatic intracranial lesions either spontaneously or during intervening events, it is possible to reclassify patients throughout the process. Thus, in patients in whom a CT scan was obtained immediately after trauma, the scan may not show intracranial lesions that can develop during the first 3-12 hours after the trauma. So some authors propose a reclassification based on the features of the last or the worst CT performed in the acute phase.

There are some other limitations of the TCDB classification. The classification takes a primarily surgical approach without considering some TBI of great clinical relevance and, above all, of great prognostic importance. This is the case of traumatic subarachnoid hemorrhage (tSAH), which currently enjoys a significant prognostic role, and was not considered in the initial TCDB classification. Currently, traumatic SAH is usually classified as diffuse brain injury type II. Other injuries often not sufficiently weighted in the classification are tomographic lesions associated with diffuse axonal injury, especially those located in the brainstem or corpus callosum. According to the TCDB classification, the presence of such lesions, often small hemorrhagic lesions on the CT scan, would be included under type II diffuse injury, which could lead to prognostic expectations anyway, but may be established a priori by the tomographic images. It is well known that in patients with diffuse axonal injury mainly affecting central brain structures, the prognosis for recovery in the medium term is uncertain. Conversely, larger hemorrhagic lesions due to concussions may be associated in general with a better clinical outcome. Hence, the TCBD classification is less powerful when used for evaluating mild TBI.

5.4.2 Greene Scale for Assessing Posttraumatic Subarachnoid Hemorrhage

The presence of tSAH on a CT scan has gained increasing relevance. Although an association between prognosis and the presence of tSAH has been demonstrated, it is equally true that there is consensus on how to classify and evaluate the presence of such lesions on the CT scan. Moreover, the clinical significance of posttraumatic SAH differs from spontaneous SAH owing both to blood volume and location. In most trauma cases, the subarachnoid blood does not usually enter the basal cisterns but rather mixes with the supratentorial and spinal fluid surrounding the cerebral hemispheres. Less frequently it is located at the level of the cisterns of the skull base, where bleeding is probably due to a different mechanism.

Greene et al. proposed in 1995 a model for weighing and assessing the severity of this entity based on a series of 252 patients at St. Joseph’s Hospital and Medical Center in Arizona enrolled over 3 years. The study included only patients with non-penetrating head wounds and abnormal CT, regardless of the degree of altered consciousness. Although the study was not designed to show a scaled analysis of SAH itself, the aim was to study whether CT findings can be considered useful in the evaluation of traumatic SAH. The main contributions of this study are that it established a systematic way to analyze traumatic SAH and that it defined a severity scale for traumatic SAH in terms of intensity in association with other pathological findings on the CT scan.

The proposed scale of CT analysis focuses on the presence or not of SAH and, if present, the evaluation of its thickness (≤5 mm or >5 mm), and its location. The anatomical locations imaged for the presence of subarachnoid blood are the interhemispheric fissure, fissure frontobasal, frontal fissure, occipitoparietal fissure, base of the Sylvian fissure, Sylvian fissure, insular cistern, suprasellar cistern, ambiens cistern, interpeduncular cistern, prepontine cistern, transverse cerebral fissure, supracerebellar cistern, and cerebral convexity. With this type of analysis, we can distinguish between those regions including the basal cisterns, vertical regions of cerebrospinal fluid, the Sylvian fissure and bleeding. Based on this distinction, the location is classified in a hierarchical manner and assigned scores of 1 to 3, where 1 refers to the presence of traumatic SAH in the hemispheric region only, 2 only located in the basal region, and 3 presence of SAH in the basal interhemispheric regions. Besides these aspects, also evaluated are the presence or absence of associated brain edema, obliteration of basal cisterns associated with SAH, mass lesions such as epidural or subdural hematoma, or the presence of concussion and midline shift >5 mm, or ≤5 mm (toward the septum pellucidum). Table 5.10 shows the Greene Scale for the classification of tSAH.

Greene KA et al. found a direct relationship between the degree on the scale and the level of consciousness (GCS) on admission of the patient. The scale also correlated statistically with the outcome, as measured by the Glasgow Outcome Scale (GOS).

The significance of SAH in patients with TBI is different in patients with spontaneous subarachnoid bleeding due to rupture of intracranial aneurysms. Both its location and because of its pathophysiology, the relationship between posttraumatic vasospasm and SAH is not as clear as it is in spontaneous SAH. Traumatic SAH is a marker of a brain damage mechanism of relevance. Thus, the presence on CT of traumatic SAH has been considered an element suggestive of mechanisms of acceleration/deceleration in the genesis of trauma, and therefore not infrequently associated with the presence of diffuse axonal injury.

Table 5.10. Greene classification of traumatic subarachnoid hemorrhage.

5.4.3 Gennarelli Scale for Rating Diffuse Axonal Injury

Gennarelli developed a scale based on previous anatomo-pathological findings by Adams in patients with diffuse axonal injury. It was the primary basis for classifying diffuse axonal injury and scales with radiological and clinical variables were later developed. Table 5.11 presents the Gennarelli classification based on pathologic findings from studies in primates, which was subsequently modified. Although initial studies were conducted in experimental animals, the results were then extrapolated to imaging studies using CT, in which it was observed that CT showed moderate sensitivity for the detection of white matter lesions accompanying diffuse axonal injury. These chances of detecting axonal injury were later exploited with the advent of magnetic resonance imaging (MRI).

The Gennarelli scale for evaluating diffuse axonal injury is currently the most widely used tool for assessing injury severity, as it indicates a direct relationship between the lesion severity and long-term neurological and functional outcomes.

In 1987, Gentry et al., using MRI studies in the acute phase of injury and comparing the radiographic findings with clinical findings, described traumatic axonal injury lesions and their most frequent locations: lobar white matter (frontal, temporal, parietal and occipital), corpus callosum (splenium, body and knee), corona radiata (anterior and posterior), capsula (internal and external), brain stem and cerebellum.

The radiological approach to the study by Gentry along with Gennarelli’s anatomical classification allows stratification of lesions secondary to diffuse axonal injury along a sliding scale, so that peripheral lesions in the lobar white matter are classified in the range of the less serious, while central brain lesions and those of the brainstem are associated with greater clinical severity.

Table 5.11. Morphological classification of axonal diffuse region. Gennarelli classification modified.

5.4.4 Fisher Scale

Developed by Fisher et al. in 1980, this scale assesses the location and extent of SAH visualized by CT, based on the observed changes in CT scans of a verified case of ruptured intracranial aneurysms, and the relationship with cerebral vasospasm (Table 5.12).

Table 5.12. Fischer scale.

Table 5.13. Fischer revised scale.

Divided into 4 grades, the scale relates the amount of blood visualized on a CT scan at the level of the cisterns, sulci and ventricles, with the possibility of developing arteriospasm. Analysis of the presence of blood should include at least the following locations: 1) frontal interhemispheric fissure, including the immediate region of the genu of the corpus callosum; 2) basal frontal fissure, including the inferomedial boundary region of the hemisphere, close to the anterior communicating artery; 3) occipitoparietal fissure (posterior interhemispheric fissure); 4) base of the Sylvian fissure (horizontal portion of the Sylvian fissure around the proximal middle cerebral artery bifurcation); 5) Sylvian cistern (bottom of the Sylvian fissure adjacent to its base and the main divisions of the middle cerebral artery); 6) insular cistern (subarachnoid space vertically oriented on the surface of insula); 7) part of the Sylvian fissure oriented horizontally and superimposed on the upper surface of the temporal lobe; 8) suprasellar cistern (region of the circle of Willis); 9) ambiens cistern (perimesencephalic space vertically oriented); 10); quadrigeminal cistern (subarachnoid space adjacent to the quadrigeminal bodies); 11) transverse cerebral fissure between the corpus callosum and the fornix above and below the diencephalon; 13) prepontine cistern located ventral to the base of the pons and superior cerebellar cistern; 14) surface of the brain.

In cases where the amount of blood that is not noticeable or is so diffuse that it forms clots >1 inch thick (grade 1 and 2, respectively), the rate of vasospasm is very low. In cases where the accumulation of blood is greater (grade 3), the risk of vasospasm increases as does ischemic neurological deterioration even more if blood occupies the wells in the vertical plane (interhemispheric fissure, insular cistern, ambiens cistern) or >3 x 5 mm in the longitudinal cisterns (Sylvian and interpeduncular).

Indications for Use and Limitations of Fisher’s Scale

The Fisher scale has its main indication in assessing the risk of developing vasospasm according to CT findings in the acute phase of aneurysmal SAH, and so may n estimate of the risk of developing ischemic focal neurological deficits associated with this situation.

The Fisher scale should not be used as a scale to estimate clinical severity or for evaluating neurological complications of spontaneous SAH. Furthermore, accurate estimation of the amount of subarachnoid bleeding as assessed by CT is not always easy. The problems for quantification are diverse: 1) irregular size of the cisterns and fissures; 2) planes that do not correspond to the inclination of the CT court; 3) difference in blood concentration in each of these regions; 4) inaccuracy in measuring the intensity in Hounsfield units (HU) due to the frequent coexistence of partial volume effect due to both the proximity of the bone and the cerebral cortex; and 5) increasing trend of isodensity of bleeding with the time.

5.4.5 Graeb Scale

In 1982 Graeb published a retrospective study of CT findings of 68 patients with intraventricular hemorrhage caused by aneurysm rupture (25%), trauma (25%), hypertensive hemorrhage (20% ) and other miscellaneous causes. The mortality rate was 50%, whereas 21% of patients who recovered didn’t have sequelae or had only mild disability.

Since the development of hydrocephalus is an important factor in the prognosis of patients with blood in the ventricles, the authors proposed a classification to assess its risk. The classification is based on the amount of blood invading the ventricles (Table 5.14). One consideration to take in mind is the “blood-filled and expanded ventricle “ which implies that the presence of ventricular dilation is directly attributable to bleeding, and not to the possible co-existence of hydrocephalus. The maximum score is 12 points, and there is some consensus that a score ≥7 allow us to evaluate this bleeding as high risk, frequently associated with a severe clinical picture. The risk of hydrocephalus is low when the score is between 1 and 4, moderate between 5-8, and severe when the total score is 9 to 12.

Table 5.14. Graeb grading scale.

The main objective of Graeb’s Scale is to quantify intraventricular blood associated with spontaneous SAH, intraparenchymal hematomas, or other processes such as tumours, and arteriovenous malformations; therefore, it may be used to estimate the risk of developing obstructive hydrocephalus.

5.4.6 Le Roux Scale

In 1992, Le Roux published the results of a series of patients with intraventricular hemorrhage secondary to head injury. This study utilized a risk scale somewhat similar to that Graeb had published 10 years earlier. The study population was 43 patients. The blood was distributed in one or both ventricles in 25 patients; in the third or fourth ventricle in 4, and in all the ventricles in 14. There were also 3 intracerebral hematomas and 14 in the basal ganglia. The presence of ventricular blood in each ventricle was evaluated on a scale with a score between 0 (no ventricular hemorrhage) and 4 (maximum degree of ventricular invasion), with a total score range from 0 to16 (Table 5.15).

Table 5.15. Le Roux grading scale.

5.4.7 Spetzler-Martin Scale

This scale was devised by Spetzler and Martin in 1986 to establish surgical risk and treatment recommendations for arteriovenous malformations (AVM). It combines clinical and radiological variables.

This grading system (Table 5.16) establishes the risk of morbidity and mortality and the most appropriate form of treatment of AVM. AVMs are classified according to the total score, based on the following criteria: size of nidus, type of venous drainage, and eloquence of adjacent brain area.

Table 5.16. Spetzler Martin Grading scale.

The size of the lesion is usually determined by the size of the malformation, which is defined on angiography: small, <3 cm (1 point); medium, 3-6 cm (2 points); and large, ≥6 cm (3 points). In general the overall AVM size is related to the number of afferent arteries.

The pattern of venous drainage is also determined by arteriography. A superficial directed to cortical venous system, straight or transverse sinus is assigned 0 points; a deep pattern (deep venous drainage, internal, basal cerebral veins or cerebellar or paracentral veins) is assigned 1 point.

The following regions are considered eloquent: sensorimotor cortex, language and visual area; hypothalamus; thalamus; internal capsule; brainstem, cerebellar peduncles; and deep nuclei. An AVM affecting an eloquent areas is assigned 1 point and 0 if no eloquent areas are affected.

5.4.8 NIH Stroke Scale (NIHSS)

The National Institutes of Health Stroke Scale (NIHSS) is a systematic assessment tool that provides a quantitative measure of stroke-related neurologic deficit. The NIHSS was originally designed as a research tool, but now has other potential utilizations such as: clinical assessment, determining treatment appropriateness (thrombolytics), and predicting outcome.

The NIHSS can be used as a clinical aid to evaluate and document neurological status in acute stroke patients, and it is valid for predicting lesion size and stroke severity. The scale is designed to be a simple, valid, and reliable tool that can be used at bedside from physicians or nurses.

The scale is composed of 15 items for neurologic examination to evaluate the effect of cerebral ischemia on levels of consciousness, language, neglect, visual-field loss, extraocular movement, motor strength, ataxia, dysarthria, and sensory loss. Each item on the scale is scored from 3 to 5 with 0 as normal (Table 5.17). Assessment takes less than 10 minutes to complete.

Table 5.17. NIH ictus scale.

5.4.9 ICH Score

In 2000 Hemphill, working at the University of California, San Francisco (UCSF), developed an outcome risk stratification scale (the ICH Score) based on 5 variables determined to be independent predictors of 30-day mortality. The variables are: GCS, age, localization, volume of hemorrhage, and presence of intraventricular extension of bleeding. Each parameter is assigned points according to the strength of association with outcome. The ICH Score is the sum of the points of the various characteristics (Table 5.18).

Table 5.18. Determination of the ICH score.

The GCS was divided into 3 subgroups (GCS scores of 3-4, 5-12, and 13-15) to reflect the influence of the GCS score on outcome. Age ≥80 years was also strongly associated with 30-day mortality, so1 point was assigned for this situation. Intraventricular hemorrhage (VH), infratentorial origin of ICH, and ICH volume had relatively similar strengths of outcome association. IVH and infratentorial origin of ICH are dichotomous variables with points assigned only when present. ICH volume was dichotomized to <30 and ≥30 cm³. Thirty cubic centimetres was chosen because it represented a cut-off point for increased mortality in the UCSF ICH cohort.

The ICH Score was an accurate predictor of outcome assessed as 30-day mortality. The range of ICH scores was 0 to 5. No patient with a score of 0 died, whereas all patients with an score of 5 died. Thirty-day mortality rates for patients with 1, 2, 3, and 4 points were 13%, 26%, 72%, and 97%, respectively. This grading scale has been validated worldwide.

5.5 Scale of Evolution, Evaluation of Consciousness in Advanced Stages of Brain Injury Outcome Scales

5.5.1 Glasgow Outcome Scale (GOS), GOS-Extended and Extended Glasgow Outcome Scale of Edinburgh (EEGOS)

The need to evaluate the health outcomes in patients who had suffered brain damage was the major reason that Jennett and Bond developed a 5-point scale that included neurological dysfunction is both intellectual and physical aggression produced by the brain. In 1975 the Glasgow Functional Outcome (GOS) scale was introduced (Table 5.19). It is now a general evaluator of spontaneous and traumatic brain lesions. Researchers working on the development of the scale considered impaired social interaction of the patients as the most important element that could evaluate the final results of the clinical process. For practical purposes, the scale includes 5 categories, ranging from Category I (death of the individual) to category V (good recovery). Category II includes persistent vegetative state, meaning a patient with no cerebral cortex functions and no reasonable behaviour even if it does not necessarily imply that the cerebral cortex is not grossly intact. Category III includes patients with severe disability, defined generically as “conscious but disabled”. This implies that such patients are independent for activities of daily living despite cognitive deficits or physical deficits. Category IV includes patients with moderate disability defined as “disabled but independent patient.” Such patients can travel by public transport and can perform work in a suitable environment and therefore are independent in these activities, but can present physical and intellectual abilities or personality changes. Category V includes patients with good recovery. Such patients return to their pre-injury activity well without cerebral deficits or with smaller physical or psychological deficits.

Table 5.19. Glasgow Outcome Scale.

The categories in the original scale were considered by some as too broad and therefore felt they could include within the same category patients with significant clinical differences. In 1981 a new version of the scale, the Glasgow Outcome Scale-Extended, was developed which includes 8 points on the scale. Death, vegetative state, complete dependence on others, dependence on others for some activities, inability to return to work or participate in social activities, return to work with reduced capacity, and reduced participation in social activities, good recovery with mild mental and social deficits and good recovery with no deficit. The extended GOS scale (GOS-E) was completed by introducing the implementation of a standardized interview format that improves the reliability and validity of results. Thus, these corrections to the original scale were intended to solve, on the one hand, the low sensitivity to reflect changes experienced by the patient, and on the other, the low reliability due to the absence of a structured interview. Compared with the GOS, the GOS-E has shown greater sensitivity to assess changes due to mild and moderate injuries.

In addition to the above, also worthy of mention is an expanded version of GOS, the so-called extended GOS Edinburgh (EEGOS) and Signorini Hellaell proposed in 1997. It establishes an 8-point scale divided into a summation of functional, behavioural, cognitive and of physical parameters.

The GOS and GOS-E scales were designed to describe the social impact that occurs as a result of brain damage of traumatic origin rather than vascular origin. Currently they are still employed in the evaluation of neurologic and mental disabilities resulting from brain damage of any origin. Important to note is how much of the GOS and the GOS-E presents the individual’s interaction with his or her environment. So, the dysfunction that may occur in this interaction may be due to psychological, physical deficits, or both.

However, these scales have attracted criticism that they focus more on physical aspects than neuropsychological deficits, and this despite the recommendations of the scales’ authors, pointing to the increasing impact of intellectual changes on physical limitations in terms of disability caused by brain damage. These scales have also received criticism that they are difficulty to use especially in children with head injuries.

5.5.2 Revised Neurological Assessment Instrument (NAIr)

The Neurological Evaluation Scale revised uses different elements to assess consciousness. The theoretical basis of the scale incorporates the physiological and neuroanatomical correlates of levels of consciousness based primarily on Plum and Posner´s publications. The scale was originally designed to assess neurological function in adults with acute brain injury. The scale items were selected to capture different aspects of the CNS and assess awareness along a continuum from alertness to coma. The clinical variables reflect the brain state, respiratory rate, pupil size and reactivity, eye movements and motor responses, operationalized nervous system functions, neuroanatomical and physiological correlations that facilitate the identification of pathology. The responses in each category are organized hierarchically, ranging from normal reflexes to the brain and progressive dysfunction of brainstem structures. The level of awareness concerning the characteristics of degree of alertness related to the brainstem reticular formation and adjacent structures ranging from the half-bridge to the hypothalamus. This level cognitive functions and emotional concerns have significant roles in attention, memory and executive functions. Eye opening, counselling skills and communication, and behavioural responses reflect a measure of vigilance. The behaviour of localization involves the integration of functions of the brainstem and cerebral cortex of both hemispheres, the spinal cord and peripheral structures. This involves the integration of motor responses and eye functions of the pupils. The original scale consisted of 10 items. The selection of these criteria was based on strong correlations with the GCS and predictive validity criteria with the GOS.

Based on the nature of consciousness and the need for establishing a minimum alert sequence to apply the scale, one must first examine the response of eye opening, eye items, and the contents of alertness, evaluating the motor responses in the last phase. When used by trained observers, evaluation with the NAIr takes <3 minutes. The evaluation study of the NAIr scale included patients with conditions of different etiology. The study population was 39 patients, of which 18 presented with stroke, 12 with brain tumours, 7 with metabolic encephalopathies, and 2 with TBI. The mean age was 60 years (range, 20-87). The authors reported no significant differences between patients with structural or metabolic injury and suggested that the instrument is valid for the evaluation of both types of patients. They recommend that the items to be included are motionless pupil in mid-position as the lowest score of the scale in the category of ocular motility, which is associated with a lesion located in the lateral pontine tegmentum. The NAIr is a summative scale, with scores ranging from 8-37, with a minimum of 8 (no answers) to 37 (oriented patient). The scale items take the values specified in Table 5.20. The scale combines 8 items reflecting motor activity, verbal and brainstem function. The results show that the NAIr is a valid scale (r=0.9189, Pearson coefficient), reliable (r=0.9057, Pearson coefficient) and easy to administer, in the assessment of awareness levels in adults with structural or metabolic brain injury.

Table 5.20. NAIr scale.

5.5.3 Behavioural Assessment Scale (NAS)

The Behavioural Assessment Scale was developed to measure the range of behavioural functions ranging from alert to coma. The authors assessed 60 patients under the effect of sedation for maxillofacial interventions. The scale was compared with the GCS and the key test of WAIS numbers. Statistical analysis showed: a Pearson correlation coefficient of 0.97 (p <0.05) for interobserver reliability, correlation coefficient, -0.90 (p <0.05) for the correlation between the NAS and the GCS; a Pearson correlation coefficient -0.62 (p <0.05) for the correlation between the NAS and the key test of the WAIS numbers. The latter was taken as a measure of behavioural validity. The scale is reliable and valid.

The NAS differentiates between two levels of sedation: high and mild sedation. Furthermore, the scale discriminates between different levels of sedation in patients with mild sedation.

In its standard form, the scale is a brief interview conducted by an observer to evaluate four categories of responses: alert/sedation, orientation, speech and motor responses. If the patient is asleep, the evaluator tries to wake him by calling him by name in a normal tone. If the patient does not respond, he is woken up. If the patient is awake, the observer must induce pain by placing pressure on a fingernail with a pencil or other hard object. Otherwise a response to painful stimulus can be elicited by pinching the trapezius muscle in the side of the base of the neck. During the interview, the patient is asked: his or her name, where he or she is including the name of the city, and the date, including year, month and day of the week. The question of why he or she is here evaluates aspects of speech, and consistency of thought. The patient is ask to repeat the phrase “neither yes or no, but not” taken from the Spanish version of the Folstein Mini Mental State Exam.

The NAS (range, 4-19) is the sum of the scores for each of the 4 categories that the scale assesses. A score of 19 represents non-response for each category. Of the 4 categories, the study of the scale, orientation highlights (confusion or loss of ability to be personal, spatially and temporally). The categories alert, oriented and speaks explain 97% of the variance. The category of motor responses is only 2%. That is, of the 4 categories, 3 seem essential to the overall score. The scale’s authors suggest that the NAS may be appropriate to the extent that it measures changes in the levels of neurobehavioral functions of patients during the recovery process and monitors them (Table 5.21).

Table 5.21. NAS evaluation scale.

5.5.4 Ranchos Los Amigos Levels of Cognitive Functioning Scale

Cognitive Scale developed by the Rancho Los Amigos (LOCF) is used to classify patients with brain injury according to their behaviour. It is based on the deterioration of the brain capacity to process information after brain injury. Generally, as a result of severe brain injury there is unusual behaviour and difficulty in self control. This scale describes the stages of recovery from coma to independent functioning on 8 levels, ranging from lack of answers to an patient awake, oriented, and resolved with appropriate behaviours. The scale takes the values shown in Table 5.22. It has good properties of concurrent validity and test-retest unreliability. However, it does not reflect small changes in cognitive functions and has very broad categories where a patient can be in several at one time. Another drawback of the scale is that it does not measure physical function.

Table 5.22. Ranchos Los Amigos Scale of Cognitive Functioning.

5.5.5 Disability Rating Scale

The Disability Rating Scale (DRS) assesses 8 items from alertness, awareness and capacity of motor responses to cognitive skills for self-care and personal independence and social adaptability. Several studies have shown its reliability, validity and good yield. It is classified into 10 levels of disability: no disability, disability, mild, moderate, moderately severe, severe disability, severe, vegetative state, severe vegetative state patient died. The scale variables are shown in Table 5.23.

5.5.6 Coma/Near-Coma Scale

Coma/Near-Coma (CNC) scale was designed to measure small clinical changes in patients with severe brain injury of traumatic and nontraumatic origin, with features close to the vegetative state or in this state. Many of the patients in a vegetative state have a stable phase (in terms of clinical rehabilitation), some are better and others are worse or die. A scale that reflects small changes has a prognostic value and views the outcome of the disease as the great value to all involved in the rehabilitation of these patients. Moreover, this scale is helpful in making therapeutic decisions by the patient management clinical team, in addition to funding agencies responsible for the care and rehabilitation treatment of patients. The scale was intended to be an extension of the CNC levels Disability Scale with more discriminative power in patients in a vegetative state. In fact, it was initially recommended for use in patients with scores between 21 and 26 on the Disability Scale. The scale is divided into 5 levels (no comma, near-coma, coma, moderate, severe and extreme) as is the score for the 11 items that compose it. These items reflect the observations of sensory and perceptual reflex responses.

Table 5.23. Disability Rating Scale (DRS).

The information provided on this scale is useful for reducing the risk in advance to guide patients to lower levels of care or withdraw from more intense rehabilitation programs. The scale was designed to provide rapid assessment of reliable and valid progress or deterioration in patients with severe brain injury. In the evaluation of coma and vegetative states, the rehabilitation staff reports that the scale is useful for discriminating between patients with low or very low awareness and those who will progress beyond these levels. The scale is easy and quick to apply. It allows the omission of some items such as the vocal response in patients with a tracheotomy, without losing reliability and ability to predict clinical changes.

For each variable a small scale test is performed with the patient, some of which require up to 5 trials. Each scale variable is assigned a score of 0, 2 or 4. The score on the scale indicates classify the patient according to 5 levels of consciousness: no comma, near-coma, coma, moderate, and severe. The scale evaluates the following: responses to auditory stimuli, verbal orders, a light stimulus for light stimulus orientation, defence reflex, olfactory responses in orientation to tactile contact, nasal reflex, moderate pain, strong pain, and vocalization.

General References

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