Lateral plantar vein thrombosis
As the tibial nerve descends towards the foot, after giving off the medial calcaneal nerve, it divides into its medial and lateral branches. The lateral plantar nerve then gives off the first branch of the lateral plantar nerve (Baxter’s nerve); with both traversing through the lower tarsal tunnel.
This space is comprised of the quadratus plantae superiorly, abductor hallucis medially and flexor digitorum brevis inferiorly. The lateral plantar nerve then traverses through this tissue plane towards its termination as the proper digital nerves; innervating the 5 th toe and the lateral half of the 4th toe.
The lateral plantar vein follows the course of the lateral plantar nerve, with thrombus of this vein, either in isolation or as an extension of a deep vein thrombosis, being a potential irritant to the nerve. This thrombus may act as a space occupying lesion compressing the nerve or produce a local inflammatory response leading to neural irritation.
Patients often present with an ill-defined pain or numbness in the lateral aspect of the foot, primarily involving the 4 th and 5 th toes. Symptoms are aggravated by weight-bearing, increased activity and tight fitting footwear.
Lateral plantar vein thrombus is an uncommon cause of lateral foot pain that can mimic the symptoms of a 4/5 digital nerve neuroma.