Assessment, Evaluation, and Diagnosis in Spinal Cord Injury
The ISNCSCI examination is the backbone
The International Standards examination is the reference standard you will be tested on. Sensory testing covers 28 dermatomes (C2 through S4-5) with light touch and pinprick each scored 0-2; motor testing covers 10 key muscles scored 0-5, yielding sensory and motor scores and the neurological level of injury (NLI) - the most caudal segment with intact sensation and antigravity strength, provided all rostral segments are intact. Sensory and motor levels can differ, and side-specific levels matter.
AIS classification hinges on sacral sparing: S4-5 light touch or pinprick, deep anal pressure, and voluntary anal contraction. AIS A requires absence of all sacral sparing. AIS B is sensory incomplete with sacral sparing but no motor preservation more than three levels below the motor level. AIS C and D are motor incomplete (voluntary anal contraction or motor sparing more than three levels below); C means fewer than half of key muscles below the NLI grade at least 3, D means at least half do. The ZPP - the most caudal intact segment - informs prognosis but not classification.
Traps
Calling a patient AIS B when sacral sparing is absent; mixing sensory and motor NLI; classifying when a limb cannot be tested because of pain, fracture, or peripheral nerve injury; forgetting that cauda equina injury is lower motor neuron and may present with areflexia and flaccidity rather than spasticity. Also remember that non-SCI lesions (brachial plexus, stroke) can mimic cord syndromes.
Worked example
A C6 tetraplegic patient has intact S4-5 light touch but no voluntary anal contraction and no motor sparing below C7. This is AIS B, not A - sacral sensory sparing alone excludes A.
Rule of thumb
No sacral sparing, no AIS B.