Table 7.

Severity grading system according to the electrodiagnostic findings.

Defined grade	Electrodiagnostic findings
Mild	Abnormality in any sensitivity testsa
	And/or abnormal median SNAPb
	And normal median CMAP
	And normal EMG finding in APB
Moderate	Abnormality in any sensitivity testsa
	And/or abnormal median SNAPb
	And abnormal median CMAPb
	And normal EMG finding in APB
Severe	Abnormality in any sensitivity testsa
	And/or abnormal median SNAPb
	And/or abnormal median CMAPb
	And positive EMG findings in APBc

SNAP, sensory nerve action potential; CMAP, compound motor nerve action potential; EMG, electromyography; APB, abductor pollicis brevis muscle.

^aTranscarpal latency, lumbrical/interossei motor comparison study, or antidromic ring finger sensory comparison study.

^bProlonged onset latency or low amplitude.

^cDenervation potentials or polyphasic, long duration, and large amplitude motor unit action potentials.