Bland used neurophysiological tests to grade the severity of carpal tunnel syndrome (CTS). This is based on a grading scheme proposed by Padua et al. The author is from Kent and Canterbury Hospital in England.
Patient selection: possible carpal tunnel syndrome
Parameters:
(1) orthodromic sensory conduction velocity from index finger to wrist in m/s
(2) motor terminal latency from wrist to abductor pollicis brevis (APB) in ms
(3) index finger sensory nerve potential (SNAP)
(4) surface motor potential from the abductor pollicis brevis (APB)
Sensory Conduction Velocity
Motor Terminal Latency
Index Finger SNAP
Surface Motor Potential APB
Grade
>= 40 m/s
<= 4.5 ms
preserved
0 or 1
< 40 m/s
<= 4.5 ms
preserved
2
> 4.5 to < 6.5 ms
preserved
3
> 4.5 to < 6.5 ms
absent
4
>= 6.5 ms
absent
5
>= 6.5 ms
absent
< 0.2 mV
6
Grade 0: no neurophysiological abnormalities
Grade 1: most sensitive tests abnormal (palm/wrist median/ulnar comparison; ring finger double peak)
Grade
Descriptor for CTS
0
normal
1
very mild
2
mild
3
moderate
4
severe
5
very severe
6
extremely severe
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