A Diabetic Man With Arm Swelling, Pain, and Numbness

A 65-year-old insulin-dependent diabetic developed end-stage renal disease. He had undergone hemodialysis therapy through a catheter in the left arm for the past 3 years. He presented with pain and swelling of the arm and had evidence of infection in the hemodialysis fistula by Neisseria .

Neurologic examination revealed the swelling of the left arm with hand weakness and sensory deficits in the median and ulnar distributions. The examination was difficult because of the patient’s severe pain. He also had decreased sensation in the median nerve distribution of the right hand, where he had a positive Phalen test. There was also distal leg weakness and areflexia in the legs with absent vibration sense in the feet and ankles and with decreased pinprick sensation up to the mid-calf. The neurologic examination was otherwise normal.

An Electromyography Test was Performed

Motor Nerve Studies

Nerve and Site	Latency(ms)	Amplitude (mV)	Conduction Velocity (m/s)
Peroneal Nerve L.	Normal ≤ 5.7	Normal ≥ 3	Normal ≥ 40
Ankle	NR	NR	–
Fibular head	NR	NR	NR

All bolded values are abnormal.

Peroneal Nerve L. (Tibialis Anterior, Recording With a Needle Electrode)

Fibular head	4.2	3	–
Knee	6.8	3	39

Tibial Nerve L.	Normal ≤ 5.3	Normal ≥ 4	Normal ≥ 40
Ankle	5.2	3	–
Pop. fossa	16.5	2	38

Median Nerve L.	Normal ≤ 4.2	Normal ≥ 6	Normal ≥ 50
Wrist	5.9	1.0	–
Elbow	10.8	1.0	48

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Ulnar Nerve L.	Normal ≤ 3.6	Normal ≥ 8	Normal ≥ 50
Wrist	4.2	0.4	–
Below elbow	9.7	0.3	43
Above elbow	22.8	0.3	9

Median Nerve R.	Normal ≤ 4.2	Normal ≥ 6	Normal ≥ 50
Wrist	4.0	6	–
Elbow	8.3	6	52

Ulnar Nerve R.	Normal ≤ 3.6	Normal ≥ 8	Normal ≥ 50
Wrist	2.7	8	–
Below elbow	6.0	8	63
Above elbow	8.0	8	60

F-Wave and Tibial H-Reflex Studies

Nerve	Latency (ms)	Normal Latency ≤ (ms)
Peroneal nerve L.	NR	54
Tibial nerve L.	NR	54
Median nerve L.	NR	30
Ulnar nerve L.	NR	30
Median nerve R.	32.6	30
Ulnar nerve R.	31.2	30
H-reflex L.	NR	34
H-reflex R.	NR	34

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 L.	NR	2.6	NR	3.1	NR	20	NR	50
Ulnar nerve L.	NR	2.6	NR	3.1	NR	13	NR	50
Median nerve R.	2.4	2.6	2.9	3.1	21	20	54	50
Ulnar nerve R.	2.3	2.6	2.8	3.1	13	13	52	50
Sural nerve L.	NR	3.5	NR	4.0	NR	11	NR	40

Electromyography Data

Muscle	Insrt Activity	Fibs	Pos Waves	Fasc	Amp	Dur	Poly	Pattern
Extensor dig. communis L.	Norm	None	None	None	Norm	Norm	None	Full
Flexor carpi ulnaris L.	Norm	None	None	None	Norm	Norm	None	Full
Abductor pollicis brevis L.	Inc	None	2+	None	Norm	Norm	None	Red
First dorsal interosseous L.	Inc	None	2+	None	Lg	Inc	None	Red
Pronator quadratus L.	Norm	None	None	None	Norm	Norm	None	Full
Abductor pollicis brevis R.	Norm	None	None	None	Norm	Norm	None	Full
First dorsal interosseous R.	Norm	None	None	None	Norm	Norm	None	Full
Tibialis anterior L.	Norm	None	None	None	Lg	Inc	None	Red

What were the Electromyography Findings?

Motor nerve conduction tests showed nonrecordable compound muscle action potentials (CMAP) when stimulating the left peroneal nerve and recording on the extensor digitorum brevis muscle and borderline conduction velocity when recording at the tibialis anterior muscle with a needle electrode. The tibial nerve motor conduction velocity was mildly slow with a borderline CMAP amplitude. The left median nerve conduction velocity was slow, and the CMAP was of low amplitude and of prolonged latency; ulnar nerve conduction velocity was slow, particularly across the elbow, and the CMAP was of very low amplitude. Tests of both median and ulnar nerves were normal on the right.

The left median and ulnar sensory nerve action potentials (SNAPs) were absent, and they were both normal on the right. There were absent H-reflexes and sural SNAPs. F-responses were absent on the left arm and leg and were mildly prolonged on the right arm.

Needle electromyography (EMG) revealed denervation potentials with large motor unit potentials in the median-and ulnar-innervated muscles of the hand, indicating axonal degeneration. Large motor unit potentials with a reduced recruitment pattern were also seen in the tibialis anterior muscle secondary to the patient’s polyneuropathy.

What is the Most Likely Diagnosis?

It was concluded that this patient had diffuse polyneuropathy from uremia and diabetes. The hand symptoms and EMG findings were diagnostic of a shunt-related ischemic monomelic neuropathy (IMN). The shunt was replaced by one placed in the inguinal area. The patient received aggressive antibiotic therapy.

IMN, a condition reported initially by Wilbourn in 1983, is caused by complete occlusion of the shunt after placement or infection and manifests by burning paresthesias and weakness in the median- and ulnar-innervated muscle; there could also be swelling. IMN occurs most frequently in diabetics, particularly those with peripheral neuropathy and atherosclerotic disease. As in this case, treatment consists of surgical removal of the affected shunt.

Other shunt-related neuropathies include a vascular steal neuropathy that occurs several months after shunt placement and is caused by reverse arterial flow away from the digits. There are also shunt-related compression neuropathies of the median and ulnar nerves. Other mononeuropathies in uremics include carpal tunnel syndrome (CTS) and other entrapments. Uremic patients can also have damage to nerves during kidney transplants.

Follow-up

The patient got progressively better and did well until 1 year later, when he presented with paresthesias and mild swelling in both hands.

Neurologic examination then was essentially normal except for a motor sensory neuropathy with a bilateral positive Phalen test and mild decreased sensation in both median nerve distribution and mild swelling of the digits.