2 Altered Mental Status and Coma: Pathophysiology and Management
Abstract
Coma is not a lack of function but should be considered a derangement of function and possibly a disruption in neuroanatomy. When there is a change in the mental status usually there are lateralizing signs, but the brain’s environment can be effected by seizures, metabolic changes, and other pathologies; it is the physician’s responsibility to evaluate these processes.
Case Presentation
A 57-year-old woman was brought to the emergency room after being found on the kitchen floor in their home after the husband returned from the store. She was lethargic and confused, and this lasted about 5 hours in the emergency room. Her deficits included some slurred speech and mild left-sided weakness, but these symptoms seemed to resolve within the hour. She was in good health and took no medication other than hormone replacement for postmenopausal symptoms. The patient reported worsening early morning mild headaches over the last 2.5 years. Upon further workup, a computed tomographic (CT) scan demonstrated a 4 cm homogeneously enhancing left frontal-parietal mass with edema and 4 mm of midline shift.
See end of chapter for Case Management.
2.1 Altered Mental Status
2.1.1 Introduction
Before discussing the causes, categories, workup, or treatment of altered mental status (AMS), it is necessary to give a brief description of the term consciousness. Although this subject has philosophical, religious, and ethical connotations, simply stated, consciousness is the awareness of one’s self and of one’s environment, which includes people, places, and things. Consciousness also includes a multitude of higher mental functions, such as concept formation and the ability to manipulate these concepts. It is the physician’s responsibility to evaluate these mental processes and compare them within the context of the patient’s age, medical condition, baseline level of mental functioning, and numerous other factors, including comparison to the average mental functioning of the general population. This chapter discusses the evaluation process, differential diagnosis, and initial management of these patients in the neurosurgical intensive care unit (NICU).
2.1.2 Definitions
There are three major categories of AMS that should be defined: delirium, dementia, and coma. Dementia is a progressive and persistent loss of cognitive function, where both short- and long-term memory are impaired. These are typically associated with disorders such as aphasia, apraxia, and agnosia, and impairments of personality, planning, and critical and cognitive thinking. 1 It is critical to understand that dementia is a diagnosis of exclusion when other behavioral manifestations, such as delirium and other psychiatric diseases, have been ruled out.
Delirium, by definition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM) 5th Edition, consists of four key features 2 :
Disturbance in attention (i.e., reduced ability to direct, focus, sustain, and shift attention) and orientation to the environment.
Disturbance develops over a short period of time (usually hours to a few days) and represents an acute change from baseline that is not solely attributable to another neurocognitive disorder and tends to fluctuate in severity during the course of a day.
A change in an additional cognitive domain, such as memory deficit, disorientation, or language disturbance, or perceptual disturbance that is not better accounted for by a preexisting, established, or evolving other neurocognitive disorder.
Disturbances in numbers 1 and 3 must not occur in the context of a severely reduced level of arousal, such as coma.
The distinction between dementia and delirium is based on etiology and the time course of the disease process. Delirium is generally due to more acute, reversible processes, whereas dementia tends to be due to chronic, irreversible diseases. The following table summarizes and provides an overview of the characteristics of each (► Table 2.1). 3 Coma is a more severe depressed state, which will be further discussed later in this chapter.
2.1.3 Approach to the Patient with Altered Mental Status
History
Because the patient most often will not be able to provide an accurate history, when evaluating the AMS patient for the first time, most of the history can be obtained from interviewing relatives or caregivers. A thorough history may reveal a recent illness, a history of drug abuse or alcoholism, depression, or a current medication list. If preceded by a trauma, mechanisms of insult and onscene reports may help guide differential diagnoses and general approach to the examination.
Physical Exam
Within the NICU, the most common method for evaluating the patient’s altered level of consciousness and confusional states is the Glasgow Coma Scale (GCS) (► Table 2.2). It is the most widely accepted score among physicians secondary to its high level of interexaminer and intraexaminer reliability. If the patient is uncooperative or confused, we should focus on the patient’s vital signs, fluid balance, and general appearance. One can suspect hepatic failure if the patient is jaundiced, possible recreational drug abuse if needle tracks are noted, or possible seizure in a postictal state if there are signs of a bitten tongue. Any change in the GCS score of 2 points or more should be taken seriously and not dismissed as artifact.
Score | Best motor response | Best verbal response | Best eye response |
1 | No response | No response | No response |
2 | Decerebrate posturing (extensor) | Incomprehensible sound | Open eyes to pain |
3 | Decorticate posturing (flexor) | Inappropriate speech | Open eyes to voice |
4 | Withdraws to pain | Confused (not oriented) | Opens spontaneously |
5 | Localizes to pain | Oriented | |
6 | Follows commands |
The neurological exam in the NICU can reveal lateralizing signs of possible intracranial pathologies. Careful attention should be given to visual fields, cranial nerves, and motor deficits. It is also prudent to notice any changes from the initial presentation. Please see Chapter 1 for an overview of the neurological exam. However, it is important to note that absence of any focal findings does not exclude the possibility of focal neurologic lesions as the cause of the patient’s delirium. If the patient is awake and alert with stable vital signs and no focal neurologic deficit, an assessment of mental status should be performed. The Mini Mental Status Examination (► Table 2.3) evaluates the patient’s overall appearance, attitude, disorders of thought or perception, mood, insight, and judgment, as well as sensorium and intelligence. Points are allotted, with scores greater than 27, between 19 and 24, between 10 and 18, and less than 9 indicating normal, mild, moderate, and severe cognitive impairment, respectively (► Table 2.2, ► Table 2.3, ► Table 2.4). 1 , 5 , 6
2.1.4 Causes of Altered Mental Status
Careful attention must be given to the time of onset and the course of cognitive decline. It is prudent always to entertain delirium as a part of the working diagnosis and to rule out medical etiologies. The causes of altered mentation in the NICU are often different than those in the emergency room. NICU patients have head trauma, strokes, intracranial surgery, or other known sources of intracranial insult that could lead to an altered level of consciousness. Many times the neurointensivist is faced with a patient that was previously alert and aware prior to deterioration. The challenge to the neurointensivist is to identify the cause of the altered level of consciousness and institute the appropriate intervention for life-threatening conditions if need be. Acute neurologic disorders can include delayed presentations of subdural or epidural hematomas or seizures with the postictal state. Other common causes include the following:
Drug or alcohol toxicity, including withdrawal syndromes (e.g., chronic alcoholics)
Metabolic disorders (e.g., hypoglycemia, thyrotoxicosis)
Infections (e.g., urinary tract infections, respiratory tract infections)
Fluid and electrolytes (e.g., hyponatremia, hypernatremia)
Cardiovascular issues (e.g., heart failure, acute myocardial infarction)
Postoperative states (more common in the elderly)
It is beyond the scope of this book to give an exhaustive list of the possible causes of AMS. ► Table 2.5 presents the categories of causes and some of the most common etiologies of AMS in each category.
Sundowning
This is a frequent, though poorly understood, symptom complex that generally occurs in patients with dementia or cognitive impairment, and usually manifests around sunset. Sundown syndrome refers to the emergence of neuropsychiatric symptoms, such as agitation, confusion, anxiety, and aggressiveness in the evening or at night. 7 It is thought to be associated with impaired circadian rhythmicity, and it appears to be mediated by degeneration of the suprachiasmatic nucleus of the hypothalamus and decreased production of melatonin. 7 Studies have shown that patients wakened from sleep during darkness experienced agitation, with a trend indicating the apparent worsening of agitation during the winter. This may suggest involvement of the circadian timing system. 2 , 8
The diagnosis is clinical. There have been no laboratory values or imaging studies associated in the literature review. Management of sundowning includes encouraging increased activity, having the patient ambulate out of bed to the chair, exposure to light therapy during the day, and keeping a quiet and a dark environment during the night. It has been shown that bright light therapy has helped with agitated patients and restlessness in the elderly and patients with dementia. 9 , 10 , 11
Nonconvulsive Status Epilepticus
Nonconvulsive status epilepticus (NCSE) can be underrecognized and can be a fairly common cause of altered mental status in the NICU. Once structural, metabolic, and iatrogenic causes of coma have been excluded, and NCSE workup should be the next step. Some clinical signs that may suggest NCSE include prominent bilateral facial twitching, unexplained nystagmus in obtunded patients, and unexplained automatisms, such as lip smacking, chewing, swallowing movements, acute aphasia, or neglect without a structural lesion. Continuous electroencephalographic (EEG) monitoring is necessary for the diagnosis and management of NCSE.
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