A 30-year-old diver sustains a C6 spinal cord injury (SCI). During rehabilitation the team notes he has preserved shoulder abduction and elbow flexion (C5/C6 roots intact) but no triceps function, finger extension, or hand intrinsics. According to the ASIA (American Spinal Injury Association) impairment scale assessment, which motor and sensory levels are expected AND what is the minimum ASIA grade for preserved voluntary anal contraction with absent perianal sensation?

• A Motor level C6; complete injury ASIA A (no motor or sensory below injury level)
• B Motor level C7; ASIA C if more than half of key muscles below NLI have strength <3/5
• C Motor level C5; ASIA D if most key muscles below NLI have strength ≥3/5
• D Motor level C6; incomplete injury ASIA B if any sensory function is preserved below the neurological level including the sacral segments ✓

Explanation

The ASIA motor level is the most caudal key muscle group with ≥3/5 strength with the segment above testing ≥5/5. With preserved shoulder abduction/elbow flexion (C5/C6 key muscles) but absent triceps (C7), the motor level is C6. ASIA B is the classification for sensory incomplete injury: sensory function is preserved below the neurological level (including sacral segments S4–S5 — tested by light touch/pin prick at perianal skin and deep anal pressure), but no motor function is preserved below the NLI. If voluntary anal sphincter contraction is present, the injury is at minimum ASIA C (motor incomplete). ASIA A = complete injury (no motor/sensory at S4–S5). ASIA D = motor incomplete with most key muscles ≥3/5.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.