Common peroneal neuropathy in patients after first-time stroke.

BACKGROUND Common peroneal neuropathies, usually located at the fibular head, are one of the causes of drop foot, a condition often evaluated in the electromyography laboratory. OBJECTIVES To study the motor conduction properties of the common peroneal nerve and its branches of distribution in patients with paralyzed drop foot, several weeks after their first stroke, assuming that its inversion position can cause neuropathy around the fibular neck. METHODS We performed peroneal nerve conduction study on 76 legs of 38 patients, 12-73 days after their first stroke. All the patients had flaccid drop foot on the involved side. The stimulating electrode was placed at the postero-lateral aspect of the fibular neck. Motor nerve conduction latency and compound muscle action potential amplitude were measured along the proximal part of the deep and the superficial peroneal nerve, comparing the paralyzed to the sound leg. Paired sample t-test and paired t-test were used to compare the nerve conduction properties between the sound and the paralytic leg. The linear liaison between the two legs was determined by Pearson coefficient and the test based on it. RESULTS The differences between motor conduction latencies and between CMAP amplitudes, comparing the paralyzed to the sound side, recorded in both the deep peroneal nerve and the superficial peroneal nerve, were statistically significant (P< 0.05). CONCLUSIONS It seems that the permanent equino-varus position of the paralyzed foot might affect common peroneal nerve conduction properties at the level of the fibular neck by demyelination, axonopathy, or both. Possible reasons for these pathological changes are nerve traction or nerve compression, but temperature changes in the paralytic leg should also be considered. Ankle-foot orthoses can be prescribed for prevention or correction of deformities of the foot and ankle and reduction of the weight-bearing forces.