A 28-year-old has an acute cervical spinal cord injury at C5 level. 48 hours later, the patient has preserved sacral sensation and voluntary anal sphincter contraction, with lower limb strength MRC Grade 0 and upper limb MRC Grade 3/5. According to the ASIA Impairment Scale (AIS), this is classified as:

• A ASIA Grade A — complete injury, no sensory/motor function below the injury level including S4-S5
• B ASIA Grade B — incomplete; sensory but NO motor function preserved below the level including S4-S5
• C ASIA Grade C — incomplete; motor function preserved below, but more than half of key muscle groups have MRC <3 ✓
• D ASIA Grade D — incomplete; motor function preserved below, with more than half of key muscle groups having MRC ≥3

Explanation

The ASIA Impairment Scale classifies spinal cord injury severity. Key distinction: ASIA B = sensory preserved below neurological level but NO motor below level (including S4-S5). ASIA C = motor function preserved below level, but more than half of key muscle groups below neurological level have MRC <3. ASIA D = motor preserved, more than half key muscles ≥MRC 3. Since this patient has sacral sensation AND voluntary anal contraction (motor preserved at S4-S5) but lower limb MRC 0 with upper limbs MRC 3 (above level), the classification depends on motor below level. Lower limbs MRC 0 means key muscles below level all <3, classifying as ASIA C (motor present but weak).

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.