Presentation
Long-standing burning sensation in the sole of the foot; weakened toes flexors and abductors.
Patient Data
A multicystic fluid intensity lesion is located in the narrow space of the fibro-osseous tarsal tunnel. It lies directly next to the neurovascular bundle and seems to exert pressure on it. It is difficult to certainly tell the origin of this lesion but on coronal slices it seems to have some connection to the posterior talocalcaneal joint.
The posterior tibial veins are mildly widened proximal to the lesion and the tibial nerve seems compressed at the level of its bifurcation into the medial and lateral plantar nerves.
Signs of atrophy of plantar muscles are visible, which appears to be chronic.
Mild cartilage signal distortion and bone marrow edema in upper ankle joint - probably degenerative. Slight synovium edema and a trace of fluid in the opening of sinus tarsi with no signs of disrupted ligaments.
Triangular osseous structure posterior and lateral to the talus - os trigonum with some degenerative changes.
No internal enhancement after intravenous contrast administration favors the diagnosis of a ganglion cyst with probable origin from the posterior talocalcaneal joint.
Case Discussion
Ganglion cysts are one of the most typical pathological causes of the symptoms of tarsal tunnel syndrome.
In this case, another point of origin of this ganglion cyst could be a sheath of the flexor tendons that travel through the tunnel. As discussed above, it is difficult to tell the origin by this study alone.
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