Intraneural and Extraneural Ganglion Cysts at the Greater Sciatic Notch Involving the Sciatic Nerve Causing Sciatica: Two Case Reports

Intraneural ganglion cysts (IGCs) are benign mucinous cysts within the epineurium of peripheral nerves. Hip joint-related IGCs are much rarer than those that arise from peripheral nerves around the joints of limbs. The unifying articular synovial theory has been accepted as explaining the pathogenesis of IGCs. Herein, we present two cases of hip joint-related ganglion cysts—one case of an IGC and one case of an extraneural ganglion cyst—that involved the sciatic nerve through the articular branch of the hip joint and caused sciatica. Preoperative and postoperative magnetic resonance imaging (MRI) findings of the articular branch derived from a paralabral cyst of the hip are presented, as well as photographic findings of a ganglion cyst with the articular branch addressed through a transgluteal approach. Despite improvement in postoperative sciatica due to cyst decompression and treatment aimed at addressing the articular branch, the articular branch remained present on postoperative MRI. Unlike IGCs arising from peripheral nerves associated with limb joints, involvement of the sciatic nerve might make it challenging to treat articular branches due to the location of the sciatic nerve over the greater sciatic notch of the deep gluteal region.