A Man With Hand Pain

A 48-year-old man had a 6-month history of pain in the right hand, occasionally radiating to the shoulder. He also had numbness with tingling in the first two digits and was referred for an EMG.

The neurologic examination was normal, except for mild weakness of the thenar muscle on the right and a positive Phalen test. There was a sensory deficit in the median nerve distribution on the right and left hands. Strength, reflexes, and sensory examinations in the legs were essentially normal.

An EMG Test was Performed

Motor Nerve Studies

Nerve and Site	Latency(ms)	Amplitude (mV)	Conduction Velocity (m/s)
Median Nerve R.	Normal ≤4.2	Normal ≥ 6	Normal ≥ 50
Wrist	6.4	6.9	–
Elbow	8.4	10.9	120

Ulnar Nerve R.	Normal ≤ 3.6	Normal ≥ 8	Normal ≥ 50
Wrist	2.8	18.0	–
Below elbow	6.4	14.4	63

Median Nerve L.	Normal ≤ 4.2	Normal ≥ 6	Normal ≥ 50
Wrist	5.2	13	–
Elbow	9.2	12	55

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Ulnar Nerve L.	Normal ≤ 3.6	Normal ≥ 8	Normal ≥ 50
Wrist	2.8	18	–
Below elbow	6.6	18	62
Median Nerve R. Recording at Adductor Digiti Minimi Muscle
Wrist	NR	NR	–
Elbow	8	3	–

F-Wave Studies

Nerve	Latency (ms)	Normal Latency ≤ (ms)
Median nerve R.	31.2	30
Ulnar nerve R.	26.2	30
Median nerve L.	30.0	30
Ulnar nerve L.	27.2	30

Sensory Nerve Studies

Nerve	Onset Latency (ms)	Normal Onset Latency ≤ (ms)	Peak Latency (ms)	Normal Peak Latency ≤ (ms)	Amp (μV)	Normal Amp ≥ (μV)	Conduction Velocity (m/s)	Normal Conduction Velocity ≥ (m/s)
Median nerve R.	4.2	2.6	4.7	3.1	4	20	31	50
Ulnar nerve R.	1.9	2.6	2.4	3.1	16	13	63	50
Median nerve L.	4.2	2.6	4.7	3.1	12	20	31	50
Ulnar nerve L.	1.8	2.6	2.3	3.1	14	13	67	50

EMG Data

Muscle	Insrt Activity	Fibs	Pos Waves	Fasc	Amp	Dur	Poly	Pattern
Deltoid R.	Norm	None	None	None	Norm	Norm	None	Full
Biceps brachii R.	Norm	None	None	None	Norm	Norm	None	Full
Flexor carpi radialis R.	Norm	None	None	None	Norm	Norm	None	Full
Flexor carpi ulnaris R.	Norm	None	None	None	Norm	Norm	None	Full
Extensor dig. communis R.	Norm	None	None	None	Norm	Norm	None	Full
Abductor pollicis brevis R.	Norm	None	None	None	Norm	Norm	None	Full
1st dorsal interosseous R.	Norm	None	None	None	Norm	Norm	None	Full