A 57-year-old right-handed White man with renal failure from glomerulonephritis had been on dialysis for 3 years and was evaluated for weakness and stiffness of his arms and legs which began 1 year before. He could not extend his right arm without experiencing pain in the biceps. There was also severe stiffness in both knees.
Neurologic examination revealed normal mentation and cranial nerves. Motor testing demonstrated that his neck flexors and extensors were normal. He had 4−/5 weakness of the proximal muscles in the arms and legs, distal legs were 3−/5, wrist extensors were 4/5, and flexors were 4+/5. Weakness was 3/5 in both hands with interossei wasting, and he had flexor contractures of the upper and lower extremities ( Fig. 95-1 ). Reflexes were absent throughout. There were no Babinski signs. Sensory examination showed decreased vibration in the toes and decreased pinprick up to the mid-legs. Coordination was normal. The rest of the examination was unremarkable.
Fig. 95-1
A , Patient showing marked proximal muscle weakness with contractures. B , Interossei muscle atrophy with interphalangeal joint contractures.
What Should be Done Next?
A comprehensive metabolic panel was normal except for blood urea nitrogen of 68 mg/dL (normal, <20 mg/dL); creatinine, 8 mg/dL (normal, <1.5 mg/dL); alkaline phosphatase, 132 IU/dL (normal, <12 IU/dL). Serum creatine kinase was 226 IU/L (normal, <200 IU/L); hematocrit was 34% (normal, 26%–50%), and hemoglobin, 11 g/dL (normal, 12–16 g/dL). Calcium was 9.9 mg/dL (normal, 8.6–10.3 mg/dL), and phosphorus, 5.2 mg/dL (normal, 2.5–5 mg/dL).
An EMG Test was Performed
Motor Nerve Studies
Nerve and Site
Latency (ms)
Amplitude (mV)
Conduction Velocity (m/s)
Peroneal Nerve R.
Normal ≤ 5.7
Normal ≥ 3
Normal ≥ 40
Ankle
NR
NR
–
Fibular head
NR
NR
NR
Knee
NR
NR
NR
Peroneal Nerve R. (Tibialis Anterior Recording-Needle)
Fibular head
6.6
1
–
Knee
9.5
1
34
Tibial Nerve L.
Normal ≤ 5.3
Normal ≥ 4
Normal ≥ 40
Ankle
NR
NR
–
Pop. fossa
NR
NR
NR
Nerve and Site
Latency (ms)
Amplitude (mV)
Conduction Velocity (m/s)
Median Nerve R.
Normal ≤ 4.2
Normal ≥ 6
Normal ≥ 50
Wrist
3.8
6
–
Elbow
8.8
6
40
Ulnar Nerve R.
Normal ≤ 3.7
Normal ≥ 8
Normal ≥ 50
Wrist
3.4
6
–
Below elbow
6.8
6
36
Above elbow
9.8
6
25
Median Nerve L.
Normal ≤ 4.2
Normal ≥ 6
Normal ≥ 50
Wrist
5.2
5
–
Elbow
10.6
5
43
F-Wave and Tibial H-Reflex Studies
Nerve
Latency (ms)
Normal Latency ≤ (ms)
Peroneal nerve R.
NR
54
Tibial nerve L.
NR
54
Median nerve R.
30
30
Ulnar nerve R.
30
30
Median nerve L.
30
30
H-reflex R.
NR
34
H-reflex L.
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)
Sural nerve R.
NR
3.5
NR
4.0
NR
11
NR
40
Median nerve R.
NR
2.6
NR
3.1
NR
20
NR
50
Ulnar nerve R.
2.4
2.6
2.9
3.1
5
13
50
50
Median nerve L.
NR
2.6
NR
3.1
NR
20
NR
50
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