Entrapment of the Lateral Plantar Nerve Distal to the Tarsal Tunnel: A Case Report

The patient is a 50-year old woman with past medical history of lupus presented to the clinic with left foot pain and was referred for electrodiagnostic evaluation of a tibial nerve entrapment. She initially had left heel pain which was diagnosed as plantar fasciitis 2 years ago by an outside clinician. She was treated with several injections of local steroid to the left heel prior to the current clinic visit. Patient developed a new onset of burning, tingling, and numbness of the left foot 8 months prior to the current clinic visit which started within a few days after the last injection to her medial heel. Patient’s heel pain improved but the tingling sensation and the radiating discomfort to the lateral side of the foot persisted. Tarsal tunnel syndrome was suspected and local cortisone injections to the tarsal tunnel were delivered twice without significant relief of the symptoms. Subsequently patient underwent tarsal tunnel release of the left foot in 2 months from the onset of her symptoms. However, she continued to experience the same level of symptoms. On the day of the electrodiagnostic study, her numbness, tingling, and burning were mainly on the 4th, 5th toes and lateral plantar aspect of the left foot sparing the dorsum of the foot. She had pain on the distal medial aspect of the left heel below the incision of the tarsal tunnel release (Figure 1). Her pain level was 6-7/10 on the visual analogue scale and worse with prolonged standing. The patient did not have much pain without weight-bearing and preferred walking over standing. She denied similar symptoms on the contralateral side, weakness, gait difficulty, or recent changes in bladder or bowel function. Her past medical history was significant for lupus and she was taking plaquenil and celecoxib. Patient denied smoking or alcohol abuse and worked as a staff in the warehouse.