[Intraneural ganglion of the peroneal nerve. A case report].

This is a report of a 70-year-old patient with spontaneous pain of the dorsum area of the left foot. A few days later there was a sudden onset of foot drop. First, an idiopathic peroneal palsy was assessed but an MRI showed a cystic tumour near the fibular head. These findings resulted in the patient attending our clinic for surgical treatment. During the operation we found an intraneural ganglion of the deep peroneal nerve and the common peroneal nerve. There was no connection with the superior tibiofibular joint. The ganglion was therefore removed. Two months after the operation the patient reported an improvement of the pain but no improvement of movement of the foot. An intraneural ganglion of the peroneal nerve derives from the superior tibiofibular joint. Given access to the articular branch, the cyst typically spreads out proximally from the deep peroneal nerve to the common peroneal nerve and to the point of the sciatic nerve. The clinical symptoms are correlated with the extent of cyst propagation. Recommended therapy would include the ligation of the aricular branch, or synovectomy, or resection of the superior tibiofibular joint and decompression of the cyst.