A Woman With Peripheral Neuropathy and Frequent Falls
A 51-year-old woman was referred for peripheral neuropathy of unknown cause. Ten months prior to the presentation, she developed a tendency to fall backward, stumbling and hitting the wall when she got up in the morning. This got progressively worse. She also started complaining of burning and tingling paresthesias in the feet.
Her past medical history was positive for hypothyroidism, and she was receiving thyroid replacement. She smoked one pack of cigarettes daily but did not drink.
General physical examination, higher cortical function, and cranial nerves were normal. There was mild weakness of foot and toe dorsiflexors bilaterally. Reflexes were 2+ in the upper extremities and absent in the legs. She had a questionable Babinski sign on the right and a definitive one on the left. Muscle tone was mildly increased. There was decreased vibration sense in the fingers, toes, ankles, and knees and decreased pinprick, touch, and temperature sensations up to the knees. Position sense was markedly decreased in the toes and decreased in the ankles. Her gait was unsteady, and she had a positive Romberg test. Coordination and the rest of the examination were normal.
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
5.2
5
–
Fibular head
12.7
4
41
Knee
14.7
4
50
Tibial Nerve R.
Normal ≤ 5.3
Normal ≥ 4
Normal ≥ 40
Ankle
4.9
8
–
Pop. fossa
14.9
6
38
Median Nerve R.
Normal ≤ 4.2
Normal ≥ 6
Normal ≥ 50
Wrist
3.7
7
–
Elbow
8.0
7
55
Nerve and site
Latency (ms)
Amplitude (mV)
Conduction Velocity (m/s)
Ulnar Nerve R.
Normal ≤ 3.6
Normal ≥ 8
Normal ≥ 50
Wrist
3.2
6
–
Below elbow
7.2
5
55
Above elbow
9.2
5
60
F-Wave and Tibial H-Reflex Studies
Nerve
Latency (ms)
Normal Latency ≤ (ms)
Peroneal nerve R.
57.8
54
Tibial nerve R.
NR
54
Median nerve R.
31.2
30
Ulnar nerve R.
32.0
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.
3.1
3.5
3.6
4.0
10
11
45
40
Superficial peroneal R.
3.4
3.5
3.9
4.0
6
8–10
41
40
Median nerve R.
2.7
2.6
3.2
3.1
21
20
48
50
Ulnar nerve R.
2.0
2.6
2.5
3.1
12
13
60
50
Median nerve L.
2.7
2.6
3.2
3.1
25
20
50
50
Medial plantar R.
NR
3.2
NR
3.7
NR
10
NR
40
Lateral plantar R.
NR
3.2
NR
3.7
NR
8
NR
40
Medial plantar L.
NR
3.2
NR
3.7
NR
10
NR
40
Lateral plantar L.
NR
3.2
NR
3.7
NR
8
NR
40
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