Peroneal neuropathy is the most frequent mononeuropathy encountered in the lower limb, resulting in foot drop. We reports a case of the unilateral peroneal neuropathy after weight reduction.
A 39-year-old women complained weakness on her left foot for two weeks. She had lost 16kg within a month. She had no comorbidity. She was, then, referred to our electromyography (EMG) laboratory. She had habitual leg crossing and weakness of the left ankle dorsiflexion and eversion (2/5) and weakness of the left toe extension (2/5). The strength of other muscles was normal. She had also hypoesthesia at the dorsum of the left foot. Deep tendon reflexes on upper and lower extremities were normal. Pathologic reflex was not elicited. The laboratory findings and imaging findings were normal.
The compound muscle action potential (CMAP) was recorded with a surface electrode placed on extensor digitorum brevis muscle (EDB) for deep peroneal nerve motor conduction study. The supramaximal stimulation was done at ankle, above, and below the fibular neck. The motor conduction velocity at the left fibular head were slowed (left : 30.0 m/s, right : 59.0m/s, normal : >40 m/s). The CMAP amplitude loss about 91% was observed at the left fibular head. Sensory nerve action potential (SNAP) showed reduced amplitudes in the left superficial peroneal sensory nerve conduction study. Other nerve conduction studies were within normal limits. Abnormal spontaneous activities were observed on needle EMG of the left tibialis anterior and peroneus longus muscles. Reduced recruitment of motor unit potentials were seen in tibialis anterior and peroneus longus muscle. Needle EMG studies of the other muscles in lower extremities were normal. These findings were compatible with conduction block and partial axonal loss of peroneal nerve around the left fibular head.
Our case report demonstrating peroneal neuropathy caused by weight loss. Many cases have been published about the correlation between peroneal neuropathy and weight loss, such as diets, malnutrition, anorexia, and severe diseases including malignant diseases, but, there have been published reports rarely in Korea. Physicians need to be alert about peroneal neuropathy which develops after weight loss. |
