Surgical treatment of schwannomas around the tarsal tunnel: a case series of 40 patients and systematic review of the literature.

Abstract

OBJECTIVE: Schwannomas in the tibial, plantar, or medial calcaneal nerves around the ankle can mimic symptoms of tarsal tunnel syndrome. Outcomes after resection of schwannomas from these nerves have mainly been reported in case reports. The objectives of this study were to investigate the presentation and results for resection of schwannomas around the tarsal tunnel in a large case series and systematically review the currently available literature. METHODS: Data from 40 patients (27 sporadic and 13 schwannomatosis cases) treated at 2 centers were retrospectively analyzed for preoperative type and duration of symptoms, schwannoma size at presentation, and outcome after resection. The following different locations around the ankle were compared: proximal to the tarsal tunnel (PTT), at the tarsal tunnel (ATT), and distal to the tarsal tunnel (DTT). The severity of symptoms was categorized in increasing order for pain only on touch, during load-bearing activities, and symptoms also at rest. Surgical outcome was assessed based on pain relief and occurrence of complications. The systematic literature review was performed using a PubMed and Embase search. RESULTS: All but 1 patient presented with pain, local at the ankle, or neuropathic pain during weight-bearing activities (13/40, 32.5%). More than half of the patients also experienced symptoms at rest (52.5%). In 14 cases, the schwannoma was located PTT, in 17 cases ATT, and in 9 cases DTT in the plantar nerves. There were no significant differences in size and symptom duration at presentation for the different locations. Tumor size did not correlate with symptom severity. Outcomes after resection were excellent, with complete pain relief in all but 1 patient (97.0%). Complications included wound infection (5%) and temporary decreased sensation on the heel (7.5%). A review of 44 previously reported cases also frequently showed complete pain relief after resection. CONCLUSIONS: The results of this study show that schwannomas around the tarsal tunnel often present with severe pain symptoms, even if the lesion is still relatively small. Resection frequently results in excellent pain relief. During surgery, it may not be necessary to open the entire length of the tarsal tunnel, thereby limiting the size of the incision, especially in schwannomas located proximally or distally to the tarsal tunnel.