A Man With Leg Pain While Walking

A 52-year-old man was referred for evaluation of intermittent pain in the legs and back for 12 years which was associated with leg numbness. The pain radiated to the right hip and leg. Initially, he was found to have an L3–L4 disk herniation, and this was treated conservatively with improvement.

During the last 5 years, he again developed pain in the legs that worsened when he walked and improved with rest, particularly when seated. He also had numbness in the right first and second toes, which had become persistent for a 6-month period, and complained of paresthesias in the soles of his feet. In addition, he gave a 3-week history of numbness in the perianal area and penis.

His past medical history was remarkable for mild glucose intolerance which improved with diet. He was involved in a motor vehicle accident and sustained a fractured clavicle in the remote past and had a history of migraine headaches. Family history was pertinent for a grandmother with diabetes.

Neurologic examination revealed normal mentation and cranial nerves. Strength was normal except for weakness of both toe dorsiflexors, worse on the right with atrophy of the extensor digitorum brevis (EDB) muscles. He was able to walk on his tiptoes and heels. Reflexes were trace at the left ankle, absent on the right, and 1+ in both knees. There were no Babinski signs. Straight leg raising was negative. He had absent vibration sense in the toes and decreased at the ankle on the right but not on the left. There were decreased vibration and pinprick sensations up to the ankles bilaterally. Penile and perianal sensation were normal, but he had no bulbocavernosus reflex. The anal sphincter tone was mildly decreased. Arterial pulses were normal. The rest of the neurologic examination was normal.

What is the Differential Diagnosis?

This patient had a history of chronic back pain with leg pain that increased while walking. This is suggestive of neurogenic claudication which could be caused by spinal stenosis but could have other causes, such as intraspinal masses. There was also a clinical suggestion of a neuropathy likely from diabetes, although other causes should also be considered. The back and leg pain were not from a neuropathy, as this usually is a distal burning pain with tingling paresthesias that occurs mainly at night and does not worsen with activity. His presentation with the asymmetric findings in the neurologic examination is suggestive of a lumbosacral disease which could have several causes, such as diabetic radiculoplexopathy, or a diabetic neuropathy with superimposed radiculopathy. A spinal canal disease is the more likely diagnosis due to the chronic nature of his condition, the back pain, lack of muscle weakness, and the history of claudication.

The pain increased over 3 weeks and was accompanied by numbness in the perianal area and penis. This could be from a mid-low cauda equina syndrome caused by spinal stenosis, or a large L4–L5 disk, or by other lesions affecting the sacral nerve roots.

What should be Done?

The fasting blood sugar and glycosylated hemoglobin were normal. Erythrocyte sedimentation rate, factor antinuclear antibodies (FANA), protein electrophoresis, and thyroid-stimulating hormone (TSH) and B ₁₂ levels were normal.

An EMG Test was Performed

What were the EMG Findings?

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	4.2	1	–
Fibular head	12.4	1	39
Knee	14.4	1	48

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Tibial Nerve L.	Normal ≤ 5.3	Normal ≥ 4	Normal ≥ 40
Ankle	4.8	10	–
Pop. fossa	16.1	8	39

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Ulnar Nerve R.	Normal ≤ 3.6	Normal ≥ 8	Normal ≥ 50
Wrist	3.2	13	–
Below elbow	6.9	13	57
Above elbow	9.2	13	52

Peroneal Nerve L.	Normal ≤ 5.7	Normal ≥ 3	Normal ≥ 40
Ankle	5.7	2	–
Fibular head	12.1	2	48

F-Wave and Tibial H-Reflex Studies

Nerve	Latency (ms)	Normal Latency ≤ (ms)
Peroneal nerve R.	59.9	54
Tibial nerve L.	60.7	54
Ulnar nerve R.	30.0	30
H-reflex R.	39.2	34
H-reflex L.	39.0	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.	3.5	3.5	4.0	4.0	14	11	40	40
Superficial peroneal R.	3.7	3.5	4.2	4.0	9	8–10	40	40
Ulnar nerve R.	2.3	2.6	2.8	3.1	17	13	52	50

EMG Data

Muscle	Insrt Activity	Fibs	Pos Waves	Fasc	Amp	Dur	Poly	Pattern
Lumbar paraspinals R.	Inc	None	1+	None	Norm	Norm	Few	Full
Gluteus medius R.	Norm	None	None	None	Lg	Inc	None	Full
Tensor fasciae latae R.	Norm	None	None	None	Lg	Inc	None	Full
Vastus lateralis R.	Norm	None	None	None	Norm	Norm	None	Full
Tibialis anterior R.	Norm	None	None	None	Lg	Inc	None	Full
Peroneus longus R.	Norm	None	None	None	Norm	Norm	None	Full
Gastrocnemius R.	Norm	None	None	None	Norm	Norm	None	Full
Tensor fasciae latae L.	Norm	None	None	None	Lg	Inc	None	Red
Tibialis anterior L.	Norm	None	None	None	Lg	Inc	None	Red
Gastrocnemius L.	Norm	None	None	None	Lg	Inc	None	Full
Deltoid R.	Norm	None	None	None	Norm	Norm	None	Full
1st dorsal interosseus R.	Norm	None	None	None	Lg	Inc	None	Red