A Diabetic Man With Hand Numbness and Fainting Spells

A 66-year-old insulin-dependent diabetic man was seen because of mild hand tremors and numbness in the first three fingers of his right hand, which made it difficult for him to play the clarinet.

Past medical history included hyperthyroidism 20 years previously for which he received radiation. He was on thyroid replacement.

He used to smoke but did not drink. Several family members had diabetes mellitus (DM). He was taking tamsulosin for prostatic hypertrophy.

General physical examination, mentation, cranial nerves, and muscle strength were normal; he had no rigidity, bradykinesia, or muscle atrophy. Reflexes were absent at the ankles, trace at the knees, and normal in the upper extremities. He had decreased vibration sense in the toes and ankles and decreased pain sensation up to the ankles. He also had marked decreased pain sensation in the right median nerve distribution. A Phalen test was positive in both upper extremities. Neck motility was normal. The rest of the neurologic examination was normal.

An EMG Test was Performed

Motor Nerve Studies

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Median Nerve R. ^a	Normal ≤ 4.2	Normal ≥ 6	Normal ≥ 50
Wrist	8.5	6	–
Elbow	13.3	6	42

Ulnar Nerve R. ^b	Normal ≤ 3.6	Normal ≥ 8	Normal ≥ 50
Wrist	3.4	7	–
Below elbow	7.3	5	47
Above elbow	10.4	5	39

Median Nerve L. ^c	Normal ≤ 4.2	Normal ≥ 6	Normal ≥ 50
Wrist	6.2	5	–
Elbow	10.8	4	45

a Terminal latency index 0.188; normal 0.343–0.353.

b Terminal latency index 0.411; normal 0.396–0.414.

c Terminal latency index 0.241; normal 0.343–0.353.

Motor Nerve Studies—cont’d

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Ulnar Nerve L. ^d	Normal ≤3.6	Normal ≥ 8	Normal ≥ 50
Wrist	2.9	16	–
Below elbow	6.5	15	48
Above elbow	8.7	15	54

Peroneal Nerve L. ^e	Normal ≤ 5.3	Normal ≥ 4	Normal ≥ 40
Ankle	6.1	0.6	–
Fibular head	13.2	0.6	40
Knee	15.5	0.6	39

d Terminal latency index 0.482; normal 0.396–0.414.

e Terminal latency index 0.327; normal 0.386–0.406.

F-Wave Studies

Nerve	Latency (ms)	Normal Latency ≤ (ms)
Median nerve R.	38.3	30
Ulnar nerve R.	32.2	30
Median nerve L.	36.3	30
Ulnar nerve L.	28.6	30
Peroneal nerve L.	63.3	54

Sensory Nerve Studies

Nerve	Peak Latency (ms)	Normal Peak Latency ≤ (ms)	Amp (μV)	Normal Amp ≥ (μV)
Median nerve R.	NR	3.1	NR	20
Ulnar nerve R.	NR	3.1	NR	13
Median nerve L.	NR	3.1	NR	20
Ulnar nerve L.	NR	3.1	NR	13
Sural nerve L.	NR	4.0	NR	11

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	Lg	Inc	None	Red
Abductor poll. brevis	Norm	None	None	None	Lg	Inc	None	Red
Abductor dig. minimi	Norm	None	None	None	Lg	Inc	None	Red
First dorsal interosseous R.	Norm	None	None	None	Lg	Inc	None	Red
Tibialis anterior R.	Norm	None	None	None	Lg	Inc	None	Red