A 28-year-old motorcyclist sustains a cervical spinal cord injury at C5. On examination, he has elbow flexion but cannot extend the elbow, has wrist extension power grade 3/5, but no hand or finger function. His ASIA Impairment Scale (AIS) grade is C. Based on the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), the neurological level of injury (NLI) is:

• A C4
• B C5
• C C7
• D C6 ✓

Explanation

The neurological level of injury (NLI) is the most caudal segment with normal motor function (grade ≥3 on manual muscle testing with the segment above grade 5) AND normal sensation bilaterally. Wrist extensors (extensor carpi radialis) are the key muscles for C6; if wrist extension is 3/5 (active movement against gravity), C6 is the lowest motor level with antigravity function. C5 muscles (elbow flexors — biceps) being strong and C7 (triceps) absent confirms NLI at C6. AIS C means incomplete injury with more than half the key muscles below the NLI have grade <3.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.