How To Address Ganglionic Cysts In The Tarsal Tunnel

Dina Stock, DPM, Cory Baxter, DPM, James Sferra, MD, Christopher Herbert, DPM, and Elizabeth Baracz, BS

Case Study One: When A Patient Has Acute Numbness Of The Toes

A 41-year-old male presented with a complaint of acute numbness of his left toes. The patient reported that the numbness began two to three months prior to his presentation. He noted the numbness was constant in his first to third or fourth toes. He also had tingling in his feet but denied shooting pains. The patient initially presented to his primary care physician who had ruled out diabetes. He could not associate any traumatic or other event or episode that preceded the onset of his symptoms. However, the patient did recall recently hearing a pop when walking barefoot in his kitchen. He stated that since that time, he had more burning in his foot and felt the numbness had been worse.
The patient’s medical history was significant for hip cysts and back pain. His only medication was celecoxib (Celebrex, Pfizer). He had no known food or drug allergies.
The lower extremity examination revealed fully intact neurovascular status of the right (uninvolved) foot. Examination of the left foot revealed decreased neurological status with absent protective sensation as tested with the Semmes-Weinstein 5.07 monofilament under the first and second digits. This was intact on the other digits but the intensity of sensation was decreased at the first and second metatarsophalangeal joint levels, and proximal to the medial malleolar level. The patient had diminished sharp/dull sensation on the left foot as well and this was greatest at the first and second toes.
The muscle strength was 5/5 for all groups tested and the muscle tone was normal. There was no Tinel or Valleix sign elicited with percussion of the tibial nerve. No ecchymosis, calor or erythema was present at any site. The patient had no pain with range of motion of the metatarsophalangeal joints (MPJs), subtalar joint or ankle joint bilaterally.
We performed electromyography/NCVs of the left foot. This revealed left posterior tibial motor, mild latency delay, diminished amplitude and normal conduction velocity. The left posterior tibial motor recording at the lateral plantar nerve of the left foot demonstrated delayed latency with diminished amplitude. The left posterior tibial motor recording at the medial plantar nerve demonstrated a much delayed latency and diminished amplitude. Recording at the ankle and stimulating at the medial plantar nerve on the left foot also showed a delayed latency with diminished amplitude. Stimulating at the lateral plantar nerve of the left foot and recording at the posterior tibial at the ankle showed a much delayed latency with diminished amplitude. The left posterior tibial F-wave was delayed in comparison to the left peroneal F-wave.
The findings were consistent with a cyst in the foot although the report stated that findings could also be suggestive of a more proximal involvement of the sciatic/S1 nerve.

The radiographic evaluation revealed no abnormalities. We obtained a MRI of the left foot using a 1.0 Tesla magnet, including T1-and T2- weighted images in the long and short axis of the foot. We identified a large multiseptated, fluid-containing cystic structure, which extended along the inferior aspect of the sustentaculum tali along the inferior surface of the flexor hallucis longus tendon. The structure was approximately 37 x 12 x 20 mm in size. The findings were compatible with a ganglion of the flexor hallucis longus tendon sheath producing impingement of the posterior tibial neurovascular bundle at the bifurcation of the medial and plantar cutaneous nerves of the distal tarsal tunnel. There was mild synovitis of the posterior tibialis, flexor hallucis longus and flexor digitorum longus tendon sheaths.

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