Tibial intraneural ganglia in the tarsal tunnel: Is there a joint connection?

Intraneural ganglia are rare entities, and, as such, their pathogenesis has been extremely controversial. Recent evidence from intraneural ganglia occurring at more proximal sites-the peroneal nerve at the fibular neck (the most common site) and the tibial nerve at the knee-has suggested an articular origin rather than de novo formation. To our knowledge, of the 10 previous reports of tibial intraneural ganglia within the tarsal tunnel by others, a joint connection to the ankle joint was only identified in 2 cases. To support a hypothesis that tibial intraneural ganglia occurring within the tarsal tunnel region arise from neighboring joints, we analyzed 3 patients retrospectively, all of whom had magnetic resonance (MR) imaging and operative intervention. One of these patients was treated by a peripheral nerve surgeon specializing in foot and ankle surgery. The other 2 patients were the only ones previously published in the literature who had MR images available for reinterpretation. In none of these cases was a joint communication appreciated by radiologists interpreting the MR images preoperatively or by surgeons intraoperatively. Our review of these same cases demonstrated radiographic evidence of joint communications with the subtalar joints. Based on our findings in this article and our knowledge of intraneural ganglia occurring at more proximal sites, we believe that tibial intraneural ganglia within the tarsal tunnel originate from neighboring joints and that their connections to the joints (pedicles) are through articular branches. The importance of these connections is 2-fold: first, for their role in the pathogenesis of this entity, and second, for their potential therapeutic implications. As is highlighted by the clinical and radiographic follow-up in the 1 patient in this article and in many previously reported at other sites, intraneural cyst recurrence can occur if surgeons do not specifically address the articular connection.