Acute Complete Foot Drop Caused by Intraneural Ganglion Cyst without a Prior Traumatic Event

Abstract

Intraneural ganglion cysts are benign soft-tissue masses located in the epineurium of peripheral nerves. They originate from nearby joint connections via articular branches. Traumatic events seem to play a role in their pathogenesis as well. Clinical manifestations include pain over the area of the cyst, palpable tender mass, hypoesthesia, and muscle weakness depending on the affected nerve. Our case highlights an uncommon clinical manifestation of this entity with acute foot drop, as the primary symptom, without any previous traumatic event, enriching by this way the current diagnostic thinking process of clinical physicians. We report a case of a 42-year-old military officer who presented to our emergency department with acute foot drop that appeared during a march. Initially, the common peroneal palsy was misdiagnosed as L5-S1 disc herniation, but investigation with lumbar MRI scan led to rejection of our primary diagnosis. After performing EMG of the lower extremity and knee MRI, an intraneural ganglion cyst of the common peroneal nerve was diagnosed. Patient was treated with surgical decompression of the cyst, followed by ligation and complete resection of the articular branch, as well as disarticulation of the superior tibiofibular joint. At a twelve-month follow-up, the patient showed significant functional recovery. This is, to the best of our knowledge, the first case of intraneural ganglion cyst manifested with an acute complete foot drop without a clear prior traumatic event. We underline the need for a high index of suspicion when dealing with cases of acute peroneal palsy without any accompanying symptoms.

Drop Foot Secondary to a Peroneal Intraneural Ganglion Connected to the Superior Tibiofibular Joint: A Case Report

“…The onset of symptoms is usually gradual, but presentations with acutely developing foot drop has also been reported. 13 Our patient presented with gradually worsening foot drop with 3 weeks of history. In the differential diagnosis, other pathological conditions, including L5 radiculopathy, sciatic neuropathy and, less frequently, lumbosacral plexopathy should be excluded.…”

A rare case of an intraneural ganglion cyst of the median nerve

“…The most widely accepted is the theory proposed by Spinner et al, saying that articular degeneration and capsular defect of a neighbouring joint may cause the fluid to track along the epineurium of the nerve and result in the formation of the cyst, which can then extend along the nerve ( 4 , 6 ) . Other theories suggest that they may arise due to myxoid degeneration of the connective tissue surrounding the nerve, be related to trauma and intraneural haemorrhage or even de novo formation from hamartomatous cell rests ( 7 , 8 ) .…”

A Rare Case of Tibial Intraneural Ganglion Cyst Arising From the Tibiofibular Joint

“…Symptoms include pain, paresthesia, and decreased strength that originates in the knee and commonly extends to the plantar surface of the foot. These findings can be mistaken for lumbar neuropathies and compression of the sacral nerve roots [3][4][5][6][7][8]. Differential diagnosis includes peripheral nerve sheath tumors, periosteal ganglions, Baker's cysts, extraneural ganglion cysts, and atypical vascular or lymphatic malformations [9][10][11][12][13][14][15][16][17][18].…”

“…MRI findings include the “tail sign”, which is a narrow neck or pedicle connecting the intraneural cyst to the joint with denervation of the popliteus muscle and atrophy. The findings of eccentric displacement of the tibial nerve fascicles by intraneural cysts are referred to as the “popliteus sign” or the “signet ring sign” [ 6 , 13 , 15 ]. Muscle denervation due to edema can be seen on T2-weighted images as hyperintensity.…”

“…Muscle denervation due to edema can be seen on T2-weighted images as hyperintensity. Muscle atrophy is also characterized by hyperintensity on T1-weighted images [ 6 , 17 , 19 ]. Articular joint connections are a possible finding but are difficult to detect on MRI or ultrasound.…”