AAEE case report #12: Common peroneal mononeuropathy at the fibular head.

Common peroneal mononeuropathies, usually located at the fibular head, are one of the many causes of foot-drop, a condition often evaluated in the electromyography laboratory. If appropriate nerve conduction studies are performed and particular muscles studied on needle myography, a satisfactory diagnosis can almost always be provided for what may be a perplexing problem clinically. With all peroneal mononeuropathies, the compound muscle action potential amplitude of the peroneal motor tibialis anterior nerve conduction studies, stimulating distal to the fibular head, is a semi-quantitative measure of the number of viable fibers supplying the tibialis anterior and allows for accurate prognostication regarding the foot-drop.