14.2 Spinal Cord Injury: ASIA Impairment Scale and Functional Rehabilitation

Spinal Cord Injury: ASIA Impairment Scale and Functional Rehabilitation

Spinal cord injury (SCI) produces catastrophic disruption of motor, sensory, and autonomic pathways between the brain and the peripheral body. Physical therapists play a central role across the continuum of care—from acute intensive care neurological classification and autonomic stabilization to long-term functional mobility training and wheelchair prescription. Mastery of the standardized International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), acute neurogenic emergencies, and level-specific biomechanics is fundamental to clinical practice.

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Pathoanatomy of Spinal Cord Trauma: Primary vs. Secondary Injury

The initial mechanical damage is the primary injury. Compression, distraction or shearing may disrupt axons, supporting tissue and blood vessels at the time of trauma. A burst fracture, for example, can displace bone into the spinal canal and injure the cord.

The secondary injury develops after the initial trauma. Bleeding, swelling, impaired blood flow and inflammation can extend tissue damage beyond that produced at impact. In the acute phase, maintaining spinal precautions and escalating new neurological or respiratory deterioration to the treating team are priorities.

Spinal Shock and Neurogenic Shock

Spinal shock is an early depression of spinal reflexes below the injury. Flaccidity and reduced or absent reflexes may be prominent at first. Reflexes recover at different times, and some patients later develop hyperreflexia and spasticity below the lesion. The bulbocavernosus reflex is a sacral reflex mediated through S2–S4. It may reappear early while other reflexes are still depressed. Its return shows activity of a reflex arc. Voluntary anal contraction and sacral sensory testing are separate examination findings.

Neurogenic shock is a circulatory emergency after loss of sympathetic tone, most often with cervical or high thoracic injury. Hypotension with relative bradycardia is a typical pattern. Spinal and neurogenic shock can coexist. In a trauma patient with hypotension, the medical team must also assess for bleeding and other causes of shock.

Perform and document a baseline neurological examination as soon as the patient's condition allows. Classify from valid examination findings and repeat the examination as the patient stabilizes or findings change. Record why any item could not be tested. Document affected classification results as not determinable if the available findings cannot establish them. An early examination describes the function found at that time. Reflex changes alone do not establish sacral sparing or determine the long-term prognosis.

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The ISNCSCI / ASIA Neurological Classification Protocol

The American Spinal Injury Association (ASIA) and the International Spinal Cord Society (ISCoS) publish the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). This section uses their ninth edition (2026).

ISNCSCI Examination Structure
├── Sensory Assessment (28 Key Dermatomes Per Side)
│   ├── Light Touch (0 = Absent, 1 = Altered, 2 = Normal; bilateral total up to 112)
│   ├── Pinprick / Sharp-Dull Discrimination (0 = Absent, 1 = Altered, 2 = Normal; bilateral total up to 112)
│   └── Deep Anal Pressure (DAP: S4-S5 sacral sparing indicator; Present or Absent)
├── Motor Assessment (10 Key Muscle Functions Per Side)
│   ├── Upper Extremity (C5 Biceps, C6 Wrist Extensors, C7 Triceps, C8 Finger Flexors, T1 Finger Abductors; Max 50)
│   ├── Lower Extremity (L2 Hip Flexors, L3 Quadriceps, L4 Dorsiflexors, L5 Toe Extensors, S1 Plantarflexors; Max 50)
│   └── Voluntary Anal Contraction (VAC: S4-S5 sacral sparing indicator; Present or Absent)
└── Zone of Partial Preservation (four entries)
    ├── Right and left motor entries: applicable when voluntary anal contraction is absent
    └── Right and left sensory entries: each applicable when S4–S5 light touch and pinprick
        are both absent on that side and deep anal pressure is absent

1. Sensory Examination

• 28 Key Sensory Points Per Side: Tested from C2 down to S4-S5.
• Modalities: Test light touch (LT) with a cotton wisp and pinprick (PP) by checking sharp–dull discrimination. Compare sensation with the cheek as a reference.
• Grading Scale:
  • 0 = Absent. Score pinprick 0 if the patient cannot reliably distinguish sharp from dull, even when contact is felt.
  • 1 = Altered. The stimulus is perceived but feels less or more intense than the cheek. In pinprick testing the patient must reliably distinguish sharp from dull for a score of 1.
  • 2 = Normal sensation.
  • NT = Not testable because of the SCI, for example when neuropathic pain prevents a reliable response. NT* indicates a non-SCI reason, such as a cast that prevents access. Record the reason in the exam comments.
• Deep Anal Pressure (DAP): Evaluated during digital rectal examination. The trained examiner applies gentle pressure to the anorectal wall and records whether the patient consistently perceives it. A present response establishes sacral sensory sparing. In the full exam, assess DAP even when S4–S5 light touch or pinprick is present.

2. Motor Examination: The 10 Key Muscle Pairs

Test ten paired key muscle functions in supine using the ISNCSCI 0–5 scale. With unrestricted joint motion, grade 2 requires full movement with gravity eliminated and grade 3 requires full movement against gravity. Test resistance for grades 4 and 5 in the muscle-specific position. If the patient cannot be placed in that position, record NT or NT* according to the cause.

• Voluntary Anal Contraction (VAC): During digital rectal examination, the trained examiner assesses whether the patient can voluntarily and reproducibly contract the external anal sphincter. A voluntary contraction establishes sacral motor sparing. Reflex contraction is a separate finding.

3. Establishing the Neurological Level of Injury (NLI)

• Sensory Level: On each side, follow normal light touch and pinprick (both grade 2) from C2 to the last segment before either score drops. If both modalities are normal at every tested point on a side, enter intact (INT) when DAP is present or S3 when DAP is absent.
• Motor Level: On each side, look for the most caudal segment with at least antigravity strength and intact motor function in every segment above it. Use the examined grades for key muscles. For segments with no routinely testable key muscle (C1–C4, T2–L1, S2–S5), assume grade 5 at or above the ipsilateral sensory level and less than grade 3 below that level for classification. This convention applies to unrepresented segments. Record NT or NT* when a key muscle itself cannot be examined.
• Motor level example: If right-sided sensation is normal through C4, a right C5 elbow flexor grade of 3 with grades of 2 or less below it gives a right motor level of C5. If sensation is normal only through C3, the inferred loss of antigravity function at C4 keeps the motor level at C3 even if the elbow flexors test normally.
• Single Neurological Level of Injury (NLI): The most rostral (most cephalad) segment among the right and left sensory and motor levels.

4. The ASIA Impairment Scale (AIS)

For apparent AIS B with no voluntary anal contraction, examine qualifying non-key functions more than three segments below each side's motor level. These can establish motor incomplete status. Count only key functions below the single NLI when distinguishing AIS C from AIS D.

5. Zone of Partial Preservation (ZPP)

The Zone of Partial Preservation (ZPP) describes retained function caudal to a sensory or motor level. The worksheet has four ZPP entries. The sacral examination determines which entries apply, including in incomplete injuries.

Record one level in each applicable field. Base the motor ZPP on examined voluntary contraction. The sensory-based motor-level inference does not extend the motor ZPP. Generally use key muscle findings. If the most caudal non-key function is the only finding that establishes motor incomplete status (AIS C or D), use its listed root level for the motor ZPP on that side.

If missing findings prevent classification of a level, AIS grade or ZPP, record ND. Use ND* when a non-SCI condition makes the result indeterminable. Keep examined scores for totals. If a documented assumption about a non-SCI impairment changes a classification result, tag the affected result with an asterisk.

Worked classification examples

• AIS A with asymmetric ZPP. All four levels are C6. There is no sacral sparing. The only retained motor function below C6 is right C7 elbow extension at grade 2. The only retained sensation below C6 is right C7 light touch at grade 1. Record motor ZPP right C7 and left C6, and sensory ZPP right C7 and left C6. The retained C7 function does not change the absence of sacral sparing.
• AIS C with motor ZPP. All four levels are T10. DAP is present and VAC is absent. The only motor function below T10 is right L2 hip flexion at grade 2. Count the segments from the right motor level: T11, T12, L1, L2. Right L2 is four segments below T10, so the combination of DAP and that motor finding makes the injury motor incomplete. None of the key muscles below the single NLI is grade 3 or higher, so this is AIS C. Record motor ZPP right L2 and left T10. Both sensory ZPP entries are NA because of DAP.
• One applicable sensory field. A patient has VAC, no DAP and absent S4–S5 light touch and pinprick on the right. Left S4–S5 pinprick is present. Both motor entries and the left sensory entry are NA. For the right sensory entry, find the most caudal dermatome on the right where light touch or pinprick is present.

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Clinical Spinal Cord Injury Patterns

The clinical pattern can suggest which pathways are most affected. Use the sacral findings from the standardized exam to establish AIS completeness. In SCI, an NLI at T1 or higher is classified as tetraplegia, and an NLI below T1 as paraplegia.

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Autonomic Dysreflexia (AD): Pathophysiology and Emergency Protocol

Autonomic dysreflexia (AD) is an acute rise in blood pressure associated with an uncontrolled sympathetic response to a stimulus below the injury. It occurs most often in people with SCI at or above T6. Bladder distension, an obstructed catheter, fecal impaction and skin pressure are common triggers.

Stimulus below the injury
        ↓
Sympathetic vasoconstriction below the lesion raises blood pressure
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Baroreflex can slow the heart, while descending inhibitory signals
cannot adequately reach the sympathetic circuits below the lesion

In an adult, a sudden rise in systolic blood pressure of more than 20 mmHg above the person's usual baseline suggests AD. An apparently ordinary blood pressure can represent a clinically important rise in someone whose resting pressure is low. Headache, flushing or sweating, blurred vision and nasal congestion may occur. The pulse may slow or accelerate, and some episodes have few symptoms.

Immediate physiotherapy response

1. Stop activity and call for assistance. Measure blood pressure and pulse. If blood pressure is elevated, sit the patient upright immediately and lower the legs if possible. Loosen restrictive clothing, binders and devices. Recheck blood pressure and pulse frequently, every 1–2 minutes until stable under the Consortium for Spinal Cord Medicine guideline.
2. Look for a trigger while monitoring. Start with the urinary system. Inspect catheter tubing for kinks or clamps and check the drainage bag. Assess for other triggers such as skin pressure if there is no apparent urinary cause. Catheter manipulation, bladder drainage and bowel examination require the appropriate trained staff and facility protocol.
3. Escalate promptly. Persistent or severe elevation requires urgent medical management. At a systolic pressure of 150 mmHg or higher, the medical team may need to lower blood pressure before catheterization or rectal examination because these procedures can further raise pressure. If the trigger cannot be resolved or pressure remains uncontrolled, obtain emergency care. Continue observation for recurrence or treatment-related hypotension after resolution.

For example, a patient with C6 SCI usually has a seated systolic pressure of 95 mmHg. A sudden rise to 120 mmHg is a 25 mmHg change and meets the adult AD recognition threshold, even with minimal symptoms. Check for a trigger and monitor the response while following the emergency plan.

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Tenodesis Grasp Biomechanics in C6 Tetraplegia

A patient with C6 tetraplegia may have usable active wrist extension but insufficient active finger flexion to grasp. A tenodesis grasp uses the passive tension of the long finger and thumb flexors. Active wrist extension draws the fingers into flexion and may bring the thumb toward the index finger. Flexing the wrist reduces passive flexor tension so the fingers can open for release.

Preserving hand function

When the patient relies on tenodesis, avoid forceful combined wrist extension and finger extension during stretching or transfers. With the wrist flexed, gently moving the fingers toward extension allows practice of the finger range with less tension in the long flexors. Practice wrist extension separately with the fingers free to flex. The aim is useful passive tension with enough joint motion for grasp and release.

Train grasp and release on objects the patient uses, such as a utensil or cup, and assess whether an adaptive grip or splint would help. Select transfer technique and hand support with the rehabilitation team based on upper-limb control, skin protection and the patient's goals. A patient being considered for nerve or tendon transfer should have hand positioning and splinting planned with the specialist team.

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Functional Mobility Expectations Across SCI Levels

The level gives a starting point for setting goals. Confirm actual strength, trunk control, respiratory needs, available equipment and transfer surfaces before selecting a mobility plan. A single neurological level does not describe all retained function.

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Clinical Case Vignette

A 22-year-old collegiate gymnast sustains a severe cervical burst fracture during a vaulting dismount. Neuroimaging demonstrates C6 vertebral comminution with spinal canal retropulsion, managed via urgent anterior cervical discectomy and fusion (ACDF) C5-C7. The early examination documents flaccidity and depressed reflexes below the injury. The team records the neurological findings and repeats the standardized examination as recovery progresses.

Two weeks after injury the patient has a repeat ISNCSCI examination: Light touch and pinprick are normal through C5, with C6 sensation graded 2/2 bilaterally. Sensation at C7 through S4-S5 is completely absent (0/2), with absent Deep Anal Pressure (DAP). Motor examination reveals: C5 biceps 5/5 bilaterally; C6 wrist extensors 4/5 bilaterally; C7 triceps and all remaining key muscle functions 0/5 bilaterally. No voluntary motor function is found below C6, and voluntary anal contraction is absent.

Diagnosis and ISNCSCI classification

• Sensory Level: Right C6, Left C6
• Motor Level: Right C6, Left C6 (C5 biceps 5/5, C6 wrist extensors 4/5 with 5/5 rostrally)
• Single Neurological Level of Injury (NLI): C6
• ASIA Impairment Scale (AIS): Grade A (Complete; complete absence of sacral S4–S5 motor and sensory function)
• Zone of Partial Preservation (ZPP):
  • Sensory ZPP: right C6, left C6. Sacral light touch, pinprick and DAP are absent. There is also no light touch or pinprick below either sensory level, so record the sensory level on each side.
  • Motor ZPP: right C6, left C6. VAC is absent, and there is no preserved motor function below either motor level, so record the motor level on each side.

Therapeutic Rehabilitation Strategy:

1. Tenodesis Preservation: The team trains grasp and release for self-feeding and chooses hand positioning that maintains usable passive flexor tension without forcing wrist and finger extension together.
2. Slide-Board Transfer Training: The patient practices the head–hips relationship and hand placement on level surfaces with a transfer board and graded assistance. Skin and shoulder loading inform equipment and technique.
3. Autonomic Dysreflexia Preparedness: The patient and family learn to recognize AD symptoms and know the patient's baseline pressure, where to obtain help and how to follow the emergency plan.

Discharge Functional Status: The patient propels a manual wheelchair with coated rims independently on level floors and uses a tenodesis grasp and an adapted utensil for self-feeding. The patient and caregiver practice board transfers with assistance and plan equipment for the home.