A Man With One Large Calf

A 47-year-old man was referred because of weakness, tightness, and pain in the right calf for 5 years, becoming worse in the past 8 months.

Past medical history was unremarkable. He smoked one pack of cigarettes a day.

His neurologic examination was unremarkable except for a large right calf with a circumference 5 cm larger than the left side ( Fig. 35-1 ) and an absent right ankle jerk. All other reflexes were normal, and there were no Babinski signs. Sensory examination, coordination, and the rest of the examination were normal.

What is the Differential Diagnosis?

Although muscle enlargement is not uncommon in neuromuscular diseases, this is usually symmetric. A focal enlargement suggests several possibilities, such as a tumor, inflammation, a muscle infarct, parasitic infections, a muscle hernia, a ruptured tendon, or, rarely, a radiculopathy with partial denervation.

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	4.5	8	–
Knee	11.4	8	49

Tibial Nerve R.	Normal ≤ 5.3	Normal ≥ 4	Normal ≥ 40
Ankle	4.6	5	–
Pop. fossa	14.4	5	41

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Tibial Nerve L.	Normal ≤ 5.3	Normal ≥ 4	Normal ≥ 40
Ankle	4.8	8	–
Pop. fossa	11.6	8	54

F-Wave and Tibial H-Reflex Studies

Nerve	Latency (ms)	Normal Latency ≤ (ms)
Peroneal nerve R.	51	54
Tibial nerve R.	53	54
Tibial nerve L.	50	54
H-reflex R.	NR	34
H-reflex L.	33.6	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.	3.3	3.5	3.8	4.0	15	13	42	40
Superficial peroneal R.	3.2	3.5	3.7	4.0	13	10	43	40

EMG Data

CRD, Complex repetitive charges.

Muscle	Insrt Activity	Fibs	Pos Waves	Fasc	Amp	Dur	Poly	Pattern
Lumbar paraspinal R.	Norm	None	None	None	Norm	Norm	None	Full
Tensor fasciae latae R.	CRD	2+	2+	Many	Lg	Norm	None	Red
Vastus lateralis R.	Myok	2+	2+	Many	Lg	Norm	None	Red
Deltoid R.	Norm	None	None	None	Norm	Norm	None	Full
Biceps brachii R.	Norm	None	None	None	Norm	Norm	None	Full
First dorsal int. R.	Norm	None	None	None	Norm	Norm	None	Full
Tibialis anterior R.	Inc	2+	2+	None	Lg	Norm	None	Red
Peroneus longus R.	Norm	None	None	None	Norm	Norm	None	Full
Gastrocnemius R.	Myok	2+	2+	Few	Lg	Norm	None	Full
Lumbar paraspinal L.	Norm	None	None	None	Norm	Norm	None	Full
Tensor fasciae latae L.	Inc	2+	2+	None	Norm	Norm	None	Red
Vastus lateralis L.	Norm	None	None	Few	Norm	Norm	None	Full
Tibialis anterior L.	CRD	None	None	None	Lg	Norm	None	Full
Gastrocnemius L.	Myok	None	None	None	Lg	Norm	None	Full