h1 class=”calibre8″>2 Classification of Spinal Cord Injury

Keywords: international standards, motor scoring, sensory scoring, classification, SCI syndromes, autonomic standards

Ryan Solinsky and Steven Kirshblum

2.1 Introduction

Accurate neurological assessment is essential after a patient sustains a spinal cord injury (SCI). The most accurate tool for assessing SCI is to perform the standardized neurological examination as endorsed by the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). ¹ These Standards define common terms used by clinicians in the assessment of SCI and describe the neurological examination (▶ Appendix 2.1). The examination and classification of a person with SCI are two different skills, and therefore will be described separately. The examination is recorded on a standardized worksheet (▶ Fig. 2.1) and allows for efficient classification of the sensory, motor, and neurological levels, as well as generation of sensory and motor index scores, determination of the clinical completeness of the injury, and impairment classification.

The ISNCSCI was developed to document selected neurological parameters at the time the exam is conducted in a clinical setting ² as opposed to incorporating all aspects of a neurological exam. While not the initial intention, these Standards have been used for inclusion/exclusion criteria for research studies, outcome measures, as well as for prognostication of neurological recovery for large groups of persons with SCI.

2.2 Examination

2.2.1 Sensory Examination

The sensory examination is performed on 28 key dermatomal points (▶ Fig. 2.1), each tested for light touch appreciation and sharp/dull discrimination bilaterally. Deep anal pressure (DAP), described below, is also a required portion of the exam. A three-point grading scale (0–2) is used, with the cheek of the face used as the control point. Testing is performed with the patient’s eyes closed or vision blocked so the patient cannot identify the site being tested. For light touch, a tapered wisp of cotton from a cotton tip applicator is moved across the skin (not exceeding 1 cm). A score of “2” (intact) corresponds to the same touch sensation as on the face and “1” if felt different from the face (either hypo or hyperesthesia). A score of “0” (absent) is used if there is no appreciation of sensation.

For the sharp/dull discrimination, a clean, disposable safety pin is used. A score of “2” is documented for sensation that is perceived the same as the face with intact ability to differentiate sharp (pin end of the safety pin) from dull (rounded edge of the pin) edge. A score of “1” corresponds to altered sensation (hypo or hyperesthesia) relative to the face while maintaining the ability to differentiate sharp from dull. A score of “0” represents absent sensation, and is also given for the inability to differentiate the sharp from dull end of the pin. If accurate sensory testing is unable to be performed due to extenuating circumstances (i.e., burns, casts, amputations, etc.), the level is designated as not testable, or “NT,” on the worksheet for that dermatome, or an alternate location within the dermatome can be tested with a notation in the comment box on the worksheet. If there is a question whether the patient can definitively discriminate between the sharp and dull edges, 8/10 correct answers is considered accurate, as this reduces the probability of correct guessing to < 5%.

A prominent pitfall in performing sensory testing is variation in the caudal extent of the C4 dermatome, at times referred to as the “C4 cape.” Variably, this cervical dermatome can extend in close proximity to the nipple line, making it easy to confuse it with the T3 dermatome. In accordance with the International Standards, if T1 and T2 dermatomes are absent and T3 appears intact, T3 should be scored as absent if there is no sensation at T4 (thereby assuming an extended C4 cape).

It is important to test the S4–S5 dermatome (< 1 cm lateral to the mucocutaneous junction of the anus) for both sharp/dull discrimination and light touch, as this represents function of the most caudal aspect of the sacral spinal cord. In addition, DAP is tested by inserting a lubricated gloved finger into the anus and applying pressure to the anorectal wall using the thumb to gently squeeze the anus against an inserted index finger. ⁴ The patient is asked if they can appreciate this digital pressure. Consistently perceived pressure is recorded as either present (YES) or absent (NO) on the worksheet. If a patient has intact sensation to sharp/dull discrimination or light touch at S4/S5, DAP is not required for classification in the current ISNCSCI exam (though the motor portion of the anorectal exam, described below, is still required). Optional elements of the sensory examination include joint movement appreciation and position sense, and awareness of deep pressure/pain, each of which can add to better characterization of an injury. Details of this testing are reviewed elsewhere (www.asialearning.com).

2.2.2 Motor Examination

The motor examination encompasses testing 10 key muscles bilaterally, which are featured on the scoring worksheet (▶ Fig. 2.1 and ▶ Appendix 2.1). It is recommended that the muscles should be examined in a rostral to caudal sequence, starting with the elbow flexors (C5 tested muscle) and finishing with the ankle plantar flexors (Sl muscle) with the patient in supine positioning to maximize reproducibility over time post injury. Muscles are graded and recorded on the standard worksheet, on a 6-point scale from 0 to 5 ⁵ without pluses or minuses to maximize interrater reliability.

Although each of the key muscles has one root listed, usually two segments innervate these muscles (i.e., for biceps—C5 and C6). If a particular muscle has a grade of 3/5, it is considered to have full innervation by at least the more rostral nerve root segment and is considered useful for functional activities. A muscle initially graded as 5/5 would be considered fully innervated by both spinal root segments (▶ Fig. 2.2).

Placing the joints in the proper position during manual muscle testing (MMT) and stabilizing above and below the joint tested is important especially if the muscles do not have antigravity strength. ¹ Careful consideration toward muscle substitution masquerading as key muscle movements must be considered. Common substitutions include forearm supination mimicking wrist extension (C6), shoulder external rotation substituting for elbow extension (C7), wrist extension with tenodesis substituting for long finger flexion (C8), and finger extension appearing as small finger abduction (T1). Triggering of co-contracting spasticity (e.g., use of active elbow flexion to trigger elbow extension spasms) may also cause inaccuracies in the motor exam if not appreciated. In the lower extremities, abdominal or adductor contractions may also appear (with or without the addition of spasticity) as hip flexion and ankle dorsiflexion may mimic long toe extension. The InSTeP training videos are recommended to fully appreciate all of these positions (www.asialearning.com).

Patient’s clinical condition may prevent the completion of an accurate examination. Limiting factors such as pain and deconditioning may be present such that the patient’s MMT only grades a 4/5. If the examiner feels that the patient would otherwise have normal strength, the muscle should be graded as a 5* to indicate that inhibiting factors were present and these should be documented in the comment box on the worksheet. When the patient is not fully testable due to any reason, such as spasticity that prevents accurate stabilization of the joint, uncontrolled clonus, severe pain, a fracture limiting the exam, the cognitive status impacting participation, or a contracture limiting > 50% of full range of motion, the examiner should record “NT” instead of a numerical score for the specific myotome.

In a patient with a potentially unstable spine, care must be taken when performing MMT. When examining a newly injured individual with a lesion below T8, the hip should not be flexed passively or actively beyond 90 degrees, as this may place too great a kyphotic stress on the lumbar spine. In this circumstance, isometric assessment of hip flexion is appropriate.

Voluntary anal contraction (VAC) is tested by inserting a lubricated gloved finger into the anus and asking the patient to “squeeze my finger as if to hold back a bowel movement.” This is graded as either present (YES) or absent (NO) in the appropriate box on the worksheet. Care must be taken during this exam for patient modesty, as well as to differentiate volitional contraction from anal spasm when the finger is inserted, or anal contraction triggered by Valsalva.

A number of optional muscles (diaphragm, deltoids, abdominal muscles, medial hamstrings, and hip adductors) may also be tested, and these may be helpful in determining motor sparing of certain regions of the spinal cord and motor incompleteness, but are not used to obtain a motor index score. Beevor sign may also be helpful in specific clinical circumstances to supporting variable thoracic denervation, though this test should not be performed during the acute stages of thoracic/lumbar injuries. The hip adductor muscles, while not used as part of the motor score, are important muscles to monitor, as they are often the first muscles to recover in the lower extremity. Outside of the key 10 key muscles, non-key muscles are also tested in limited scenarios (as described below).

Although not a part of the ISNCSCI, deep tendon reflex testing may be useful to regularly assess along with anal wink and bulbocavernosus reflex for identifying phases of spinal shock ⁶ and identification of upper versus lower motor neuron dysfunction. Spasticity and autonomic assessments can also help providers develop a more comprehensive understanding of an individual’s deficits, and are described elsewhere.

2.3 Terminology

Tetraplegia: It is preferred to the term quadriplegia and is defined as impairment or loss of motor and/or sensory function in the cervical segments of the spinal cord due to damage of neural elements within the spinal cord. It does not include injury to the peripheral nerves outside the neural canal. ¹

Paraplegia: It refers to an impairment of motor and/or sensory function in the thoracic, lumbar, or sacral (but not cervical) segments of the spinal cord secondary to the damage of neural elements within the spinal canal. The terms quadriparesis (tetraparesis) and paraparesis are discouraged because they describe incomplete lesions imprecisely.

Sensory level: It is the most caudal dermatome to have normal (score of 2) sensation for both sharp/dull discrimination and light touch. This is determined by a grade of 2 (normal/intact) in all dermatomes beginning with C2 and extending caudally to the first segment that has a score of < 2 for either sharp/dull discrimination or light touch. The intact dermatome level located immediately above the first dermatome level with impaired or absent light touch or sharp/dull discrimination is designated as the sensory level (one for each side of the body).

If sensation is abnormal at C2, the sensory level is designated as C1. ¹ If sensation is intact through S4–S5, the sensory level should be recorded as intact (“INT”) rather than as S4–S5. If the patient is unable to reliably appreciate sensation when tested on the face, then “NT” should be recorded and “ND” (not determinable) should be documented in the appropriate area on the worksheet with no sensory level given.

Sensory index scoring: This provides a means of numerically documenting changes in sensory function and is calculated by adding the scores for all dermatomes. If “NT” has been documented at any level, then a sensory score cannot be calculated.

Motor level: It is defined as the lowest key muscle that has a grade of at least 3, provided all key muscles represented by segments rostral to that level are graded as 5. ¹ The motor level may differ by side of the body; a single motor level would be the more rostral of the two. If “NT” has been documented as part of the exam and this muscle is required for determination of the motor level, the designation of the motor level for that side should be deferred and “ND” is documented on the worksheet.

The myotomes that are not clinically testable by MMT (i.e., above C5, T2–L1, and S2–S5) are assumed to have full innervation if sensory innervation for sharp/dull discrimination and light touch are also intact at the level and rostrally. For example, if the sensory level is C4 and there is no C5 motor function strength (or strength graded as < 3), the motor level is C4. In a case where the C5 motor function is graded ≥ 3 on both sides of the body, with a sensory level on the left at C4 and on the right at C3 (the right C4 dermatome is impaired); the motor level on the left would be C5 and on the right it would be C3. Since the C4 dermatome on the right is impaired, it is presumed that the C4 myotome is also impaired. Therefore, the motor level is designated as C3, since the patient does not meet the criteria of having a key muscle function (in this case the C5 muscle) ≥ 3/5 with the levels above (in this case C4) scoring as normal. On the left side, the C4 dermatome is normal so the C4 myotome is considered normal, and as a result the left motor level is C5.

It is important to recognize and document if neurological injury is unrelated to SCI. For example, in a patient with a thoracic level injury who also has a brachial plexus injury, a note should be made in the comment box on the worksheet to correctly classify the patient’s spinal level of injury (thoracic level), rather than assigning a higher (cervical) level due to a non-SCI-related injury.

Motor index scoring: It is calculated by adding the muscle scores of each key muscle group. It is recommended to separate the motor scores into two scores: one for the upper limbs and one for the lower limbs. ^1,7 The motor scores provide a means of numerically documenting changes in motor function. If “NT” has been documented, then a motor index score cannot be calculated.

Neurological level of injury: This is used when determining the American Spinal Injury Association [ASIA] Impairment Scale (AIS) classification grade and refers to the most caudal segment of the spinal cord with normal sensory and antigravity muscle function on both sides of the body, provided that there is normal (intact) sensory and motor function rostrally. If the motor level is C7 and the sensory level is C8, the overall single neurological level of injury (NLI) is C7. The motor level and upper extremity motor index score better reflect the degree of function as well as the severity of impairment and disability, relative to the NLI, after motor complete tetraplegia. ⁸ This is because the sensory level may place the neurological level more rostral, thereby incorrectly implying poorer function.

Zone of partial preservation: It is defined as the dermatomes and myotomes caudal to the sensory and motor levels that remain partially innervated in an individual with a neurologically complete (AIS A) injury (see below). ¹ The zone of partial preservation (ZPP) should be recorded on the worksheet by documenting the most caudal segment with some sensory and/or motor function. A single segment for each ZPP rather than the entire range of partially innervated segments should be documented. For example, in an individual with AIS A tetraplegia, if the right sensory level is C5 and some sensation extends to C8, then C8 is recorded as the right sensory ZPP. For ZPP description, motor function does not follow sensory function (i.e., in a case of a T6 level of injury, impaired sensation at T7 does not imply there is intact/impaired motor function at T7). If there is no ZPP (no partially innervated segments below a motor or sensory level), the motor or sensory level should be entered as the ZPP. ¹ With an incomplete injury, the ZPP is not applicable and “NA” is recorded.

2.4 Classification of Injury

Utilizing a standard method of neurological assessment is important to help determine the course of recovery and the effect of interventions in the treatment of SCI. There have been many systems developed for the classification of SCI that have been based on bony patterns of injury, mechanism of injury, neurological function, and functional outcome, ^{9,10,11,12,13,14,15} and a full history is reviewed elsewhere. ^16,17 The ISNCSCI is currently the most valid and reliable classification to assess SCI and is used by the Model System Spinal Cord Injury database. A computerized classification program has been developed utilizing this schema ^18,19 and algorithms are available at www.ISNCSCIalgorithm.com and http://ais.emsci.org. The ISNCSCI exam is composed of determining the NLI and assigning a grade based on completeness of injury through the AIS.

A number of articles have posed challenging cases as well as some potential improvements to the classification ^{20,21,22,23,24,25}; however, the current classification has remained unchanged since 2015. Other scales and examination techniques have also been described, ^26,27,28,29 some of which utilize additional muscle groups, such as used in the NASCIS trials. ²⁹ El Masry et al, however, found the ASIA and NASCIS motor scoring systems comparable in representing motor deficits and recovery. ³⁰ The ISNCSCI has been found overall to be valid, reliable, and sensitive to change, most especially in patients with neurologically complete injuries. ^{25,31,32,33,34,35,36,37}

A neurologically complete injury is defined as the absence of sensory and motor function in the lowest sacral segments (no sacral sparing), whereas an incomplete injury is partial preservation of sensory and/or motor function as determined by examination of the most caudal segment (S4–S5) (sacral sparing). Sacral sparing is tested by sharp/dull discrimination and light touch at the anal mucocutaneous junction (S4/S5 dermatome) on both sides, as well as testing VAC of the external anal sphincter (the motor aspect) and DAP as part of the rectal examination. If any of these are present (representing sacral sparing), intact or impaired, even on one side, the individual has an incomplete injury. According to this definition, a patient with cervical SCI can have sensory and motor function in the trunk or even in the legs, but unless sacral sparing is present, the injury is classified as “complete” with a large ZPP. When sacral sparing is used to define incompleteness, motor recovery is significantly more likely to occur than when it is not. ⁹ The sacral sparing definition of the completeness of the injury was adopted by the ASIA Standards Committee in 1992. ¹⁰ Prior to this, an injury was considered “incomplete” if motor or sensory function extended more than three levels below the injury. The sacral sparing definition has been considered a more stable definition, because fewer patients convert from incomplete to complete status over time post injury. ⁹

The AIS has five grades, which are listed in ▶ Table 2.1. The determination of the AIS is described in ▶ Table 2.2.

AIS A: Motor and sensory complete. No sacral sparing including sharp/dull discrimination or light touch sensation at any of the S4–S5 dermatomes; no VAC and no DAP. In this case, a ZPP is documented on the worksheet. If the injury is complete, the worksheet will read “N-O-O-O-O-N” across the bottom—“no” for VAC, the four 0s for no S4–S5 sensation for light touch or sharp/dull discrimination modalities on either side of the body, and another “no” for DAP. ²

AIS B: Motor complete and sensory incomplete. Sensory but not motor function is preserved at the most caudal sacral segments S4–S5, and no motor function is preserved more than three levels below the motor level on either side of the body.

AIS C: Motor incomplete. Motor function is preserved at the most caudal sacral segments on VAC or the patient meets the criteria for sensory incomplete status (sensory function preserved at the most caudal sacral segments (S4–S5) by light touch, sharp/dull discrimination or DAP), with sparing of motor function more than three levels below the ipsilateral motor level on either side of the body. This spared motor function includes key or non-key muscles (see ▶ Table 2.3) or VAC to determine motor incomplete status. For AIS C, less than half of a key muscle functions below the single NLI have a muscle grade of 3/5. ³

Non-key muscles more than three levels below the motor level on each side should be tested ¹ in case of sensory sacral sparing when there are no key muscle functions present more than three levels below the motor level to differentiate between AIS B and AIS C. The presence of any muscle function in these muscles should be documented in the comments section of the worksheet.

AIS D: Motor incomplete status as described above, with at least half (half or more) of the key muscles below the single NLI having a muscle grade of ≥3.

It is important to note that to distinguish AIS C versus AIS D, the motor scores below the single NLI are used, whereas to distinguish between an AIS B and AIS C, the motor level on each side of the body is utilized. The reason for using the motor level to distinguish an AIS B versus AIS C is to avoid the possible situation when a patient may regain sensation in a single additional caudal level, changing the AIS from “C” to a “B.” For example: a patient initially had a motor level of C5 and a sensory level of C4 with sensory sparing at S4/S5 and some motor sparing only in C6–C8. Using the neurological level, this patient would qualify for AIS C, since C8 motor is more than three levels below the neurological level (C4). If the patient regains normal sensation over time in the C5 dermatome (with no other changes), the neurological level becomes C5 and the patient would revert from an AIS C to B because C8 is no longer more than three levels below the neurological level, indicating “worsening” despite neurological improvement. This is avoided by using the motor level, since the designation is independent of the sensory level.

AIS E: All components of the standardized neurological examination are normal. The grade E is used in follow-up when testing an individual with a previously documented SCI that has recovered normal function. If at initial testing no neurological deficits are found, then the AIS does not apply.

For pediatric patients, training for the examination is well described in the WeeSTeP (www.http://asia-spinalinjury.org/learning/). The comprehensive examination of the ISNCSCI is thought to be too complex for the cognitive abilities and tolerance of children younger than 6 years ^38,39,40,41 and some patients as old as 8 years may have difficulty with the exam. ^38,40 As periodic updates to the ISNCSCI classification occur, the reader is encouraged to visit the ASIA learning website for the most up to date classification rules.

2.5 Incomplete SCI Syndromes

A variety of clinical SCI syndromes have been previously described and include central cord, Brown-Sequard, anterior cord, posterior cord, and discomplete syndromes. Majority of these syndromes have remained largely unchanged since they were originally noted in literature, with the exception of central cord syndrome. Cauda equina and conus medullaris syndromes are also important to understand with respect to SCI, though are outside of the scope of this text.

Central cord syndrome (CCS) is the most common of the incomplete injury syndromes, accounting for 9% of all traumatic SCI and approximately 50% of incomplete injuries. CCS is characterized by motor weakness, which is greater in the upper extremities than the lower extremities, in association with sacral sparing. ^42,43 At the level of injury there is lower motor neuron (LMN) weakness as well as sensory loss, with upper motor neuron (UMN) paralysis below the lesion level. In addition to the motor weakness, other features include bladder dysfunction and varying sensory loss below the level of the lesion. CCS most commonly occurs in older persons with existing cervical spondylosis who suffer a hyperextension injury, typically from a fall, followed by motor vehicle crashes. However, CCS may occur in persons of any age and is associated with other etiologies, predisposing factors, and injury mechanisms also. The postulated mechanism of injury involves compression of the cord both anteriorly and posteriorly by degenerative changes of the bony structures, with inward bulging of the ligamentum flavum during hyperextension in an already narrowed spinal canal. ^{42,43,44,45,46,47} Occurring with or without fracture or dislocation, CCS was initially described to be caused by hemorrhage to the central cord. Subsequent research, however, has not supported this and instead identifies that the deficits are predominately due to white matter lesions, with potential further gray matter involvement (when accompanied with LMN findings in upper extremities). ^44,45 The finding that the upper extremities are relatively more involved than the lower extremities was initially postulated due to more central location of fibers of the upper limb within spinal cord motor tracts (with the lower limbs more peripherally located). ^42,46 This has been challenged, with more recent studies being supportive of a disproportionate distribution of the corticospinal tract contributing to hand and upper extremity function, thereby any injury to the tract leading to more accentuated symptoms in these areas. ⁴⁸ Definitive diagnostic criteria for traumatic CCS remain unclear with a lack of consensus on the degree of upper extremity weakness or lower extremity sparing required for classification. ^49,50

Research has demonstrated the degree of motor discrepancy between upper and lower extremities does not prognosticate recovery, instead, the AIS remains most predictive of recovery. ⁵¹ CCS usually has a favorable prognosis. ^47,52,53,54 The typical pattern of recovery occurs first and to the greatest extent in the lower extremities, followed by bowel and bladder function, upper extremity (proximal), and finally intrinsic (distal) hand function. The prognosis for functional recovery of ambulation, activities of daily living (ADL), and bowel and bladder function are dependent upon the patient’s age, with a less optimistic prognosis in older patients relative to younger patients. ^53,54 Patients < 50 years of age are more successful in achieving independent ambulation than older patients (87–97 vs. 31–41%). Similar differences were seen between the younger and older patients in independent bladder function (83 vs. 29%), independent bowel function (63 vs. 24%), and dressing (77 vs. 12%). However, for patients with initial neurological examinations (within 72 hours) classification of AIS D tetraplegia, prognosis for recovery of independent ambulation is excellent, even for those whose age is > 50 years. ⁵⁵

A syndrome with similar clinical features of upper extremity paresis or paralysis, with minimal to no lower extremity involvement is cruciate paralysis. ^{56,57,58,59,60,61} This may occur with fractures of C1 and C2, and subsequent neurological compromise of the brainstem at the cervicomedullary junction. ⁵⁷ This contrasts CCS that is usually localized in the mid to lower segments of the cervical spinal cord (i.e., C4–C5). Respiratory insufficiency occurs in roughly 25% of patients with cruciate paralysis and cranial nerves can also demonstrate deficits. Overall, the prognosis for cruciate paralysis is excellent, with studies noting more than 50% of patients with complete recovery. ⁵⁷ Wallenberg proposed an anatomical explanation for this clinical syndrome, ⁶² suggesting that the decussation of the fibers to the upper limb lay in a more rostral, medial, and ventral location in the cervicomedullary junction compared to a more lateral and caudal location of the lower limb decussating fibers. Therefore, injury to the canal, where the upper extremity fibers travel alone after decussation, causes preferential injury to the upper limbs. Neuroanatomical evidence to support this hypothesis, however, has not been found. ⁶³

Brown-Sequard syndrome (BSS) is characterized by asymmetric paresis with hypoalgesia more marked on the less paretic side and accounts for 2 to 4% of all traumatic SCI. ^{62,63,64,65,66,67,68} In the classic presentation of BSS, there is: (a) ipsilateral loss of all sensory modalities at the level of the lesion; (b) ipsilateral flaccid paralysis at the level of the lesion; (c) ipsilateral loss of position sense and vibration below the lesion; (d) contralateral loss of pain and temperature below the lesion; and (e) ipsilateral motor loss (UMN) below the level of the lesion.

Understanding the underlying neuroanatomy allows for insight into this constellation of signs. Spinothalamic tract decussation within the spinal cord leads to contralateral loss of pain and temperature when injured. Corticospinal and dorsal column tracts decussate within the brainstem, explaining for clinical findings of loss of motor, proprioception, and vibration sense ipsilateral to the lesion.

Although BSS has traditionally been associated with knife injuries, a variety of etiologies, including those that result in closed spinal injuries with or without vertebral fractures may be the cause. ^67,68,69 In addition, neoplastic causes and intramedullary inflammatory lesions, such as in multiple sclerosis, can result in partial or complete BSS. In clinical practice, the presentation of pure BSS is relatively rare. More often, patients present clinically with a combination of features of BSS and CCS, with varying degrees of ipsilateral hemiplegia and contralateral hemianalgesia. This has been termed as Brown-Sequard-plus syndrome. ⁶⁷

Despite the variation in presentation, considerable consistency is found in the prognosis of BSS. Recovery usually takes place in the ipsilateral proximal extensors and then in the distal flexors. ^70,71 Motor recovery of any extremity having pain/temperature sensory deficit occurs before the opposite extremity and these patients may expect functional gait recovery by 6 months.

Of the patients with BSS, 75 to 90% ambulate independently at discharge from rehabilitation and nearly 70% perform functional skills and ADL independently. ^51,69,73 The most important predictor of function is whether the upper or lower limb is the predominant site of weakness. When the upper limb is weaker than the lower limb, patients are more likely to ambulate at discharge. ⁶⁷ Recovery of bowel and bladder function is also favorable, with continence achieved in 82 and 89% patients, respectively. ⁶⁷

The anterior cord syndrome (ACS) accounts for 2.7% of traumatic SCI and classically involves a lesion affecting the anterior two-thirds of the spinal cord while preserving the posterior columns. ACS may occur from retropulsed disc or bone fragments, ⁷² direct injury to the anterior spinal cord, or most commonly with vascular injury or occlusion of the anterior spinal artery that provides the blood supply to the anterior spinal cord. ⁷³ This vascular etiology can occur during surgery to the aorta (especially with clamping above the renal artery) or other processes that could decrease blood flow to the spinal cord (i.e., vertebral burst fracture). In ACS, there is a variable loss of motor as well as pinprick sensation with a relative preservation of light touch, proprioception, and deep-pressure sensation. Usually patients with ACS have only 10 to 20% chances of muscle recovery and even in those with some recovery, there is poor muscle power and coordination. ⁷⁴

The posterior cord syndrome is the least frequent of incomplete SCI syndromes and has been omitted from recent versions of the International Standards. It is characterized by preservation of pain, temperature, and touch appreciation with varying degrees of motor preservation, and an absence of all dorsal column function. Prognosis for ambulation is poor, secondary to the proprioceptive deficits.

Neurological pathways within the spinal cord may be spared even after a neurologically complete injury on clinical exam. The term discomplete injury was introduced by Dimitrevic and colleagues ^75,76 to describe a clinically complete SCI with neurophysiological evidence of residual function and connectivity above and below the injury. Subsequent studies have demonstrated degrees of intact localization with quantitative sensory testing below the neurological level of injury in complete injuries (AIS A) without sparing of clinical motor, light touch or sharp/dull edge discrimination. ^{44,78,79,80,81}

Finnerup et al performed quantitative sensory testing (including thermal stimulation, pressure, pinch, and pain sensitivity) in 24 subjects with AIS A (with no sparing of voluntary motor function or preserved sharp/dull edge discrimination or light touch sensation below the injury), they found that 50% had vague localized sensation to the stimuli. ⁸¹ All patients had no cortical response to lower extremity (posterior tibial nerve) somatosensory evoked potentials. There was no relationship between the presence of this sensory perception and the level of injury or etiology. There was also no correlation between the presence of sensory perception and the presence or severity of spasticity or chronic neuropathic pain. ⁸¹

Neuropathological studies found a similar percentage (50%) of anatomically discomplete injuries in persons with clinical evidence of complete injuries. ^44,75 Furthermore, recent research on epidural stimulation in clinically complete injuries suggests the presence of such latent tracts. ⁸² However, it is still unclear where the spared information travels and what the preservation of these pathways represents. Knowledge of retained neural communication across a spinal cord injury may have consequences for treatment strategies and enhancing functional recovery. Further study is required in this area.

2.6 Autonomic Assessment

In addition to paralysis and sensory deficits following SCI, autonomic dysfunction may also play a prominent role and it includes difficulty with regulation of cardiovascular, bronchopulmonary, sexual, sudomotor, and other autonomic functions. ^83,84 Assessment of autonomic function is inherently complicated by the complexity of the autonomic nervous system. However, a systemic evaluation tool, the International Standards to determine remaining Autonomic Function after Spinal Cord Injury (ISAFSCI), has been developed by ASIA and the International Spinal Cord Society. ⁸⁵ (▶ Fig. 2.3). The Autonomic Standards allow for documentation of general autonomic, urinary bladder, bowel, and sexual function. Recent evaluations have shown moderate to good interrater reliability of the ISAFSCI (Kappa 0.41–0.88 for its various subscales), ⁸⁶ though planned revisions are ongoing. ⁸⁷ Previous versions of these standards ⁸⁸ also contained guidelines for documenting urodynamic evaluations, though this is not currently included in the required forms.

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Traumatic Atlantoaxial Rotatory Fixation Cranioskeletal Traction for the Management of Trauma to the Cervical Spine Traumatic Cervical Myelopathy Penetrating Injuries to the Cervical Spine Clinical Trials Update: Where Do We Go from Here? Initial Assessment (Including Imaging) of Cervical Spinal Cord Injury

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