A neurophysiological grading scale for carpal tunnel syndrome

Muscle Nerve. 2000 Aug;23(8):1280-3. doi: 10.1002/1097-4598(200008)23:8<1280::aid-mus20>3.0.co;2-y.


Different ways of expressing the severity of carpal tunnel syndrome (CTS) are found in the existing literature and in clinical records. This paper documents the distribution of patients on a scale based upon the nerve conduction study findings, which are largely independent of the exact normal values used in any given laboratory and demonstrate a highly significant linear relationship between the neurophysiological grading and a numerical score derived from the clinical history. Patients with more characteristic stories of CTS generally have higher neurophysiological grades. The scale is as follows: normal (grade 0); very mild (grade 1), CTS demonstrable only with most sensitive tests; mild (grade 2), sensory nerve conduction velocity slow on finger/wrist measurement, normal terminal motor latency; moderate (grade 3), sensory potential preserved with motor slowing, distal motor latency to abductor pollicis brevis (APB) < 6.5 ms; severe (grade 4), sensory potentials absent but motor response preserved, distal motor latency to APB < 6. 5 ms; very severe (grade 5), terminal latency to APB > 6.5 ms; extremely severe (grade 6), sensory and motor potentials effectively unrecordable (surface motor potential from APB < 0.2 mV amplitude).

MeSH terms

  • Carpal Tunnel Syndrome / diagnosis*
  • Electrodiagnosis / methods*
  • Electrodiagnosis / standards
  • Humans
  • Linear Models
  • Median Nerve / cytology
  • Median Nerve / physiology
  • Motor Neurons / physiology
  • Neural Conduction / physiology
  • Neurons, Afferent / physiology
  • Reaction Time
  • Reproducibility of Results
  • Retrospective Studies
  • Severity of Illness Index*