Fibular Nerve Palsy Secondary to Synovial Cyst: An Uncommon Cause of Foot Drop

https://doi.org/10.63923/smhs.2025.30

Abstract

Foot drop syndrome is defined as the inability to perform ankle dorsiflexion and is most commonly caused by compressive neuropathy of the common fibular nerve. Although several etiologies may be implicated—such as trauma, prolonged limb positioning, and neoplasms—compression by synovial cysts represents a rare and underreported cause, particularly when located at the proximal tibiofibular joint. We report the case of a young, previously healthy female patient who presented with lateral leg pain and progressive motor deficit, ultimately evolving into complete dorsiflexion paralysis. Electroneuromyography revealed a severe lesion of the common fibular nerve. Despite the absence of abnormalities on magnetic resonance imaging, surgical exploration identified a synovial cyst infiltrating the nerve. Complete excision of the lesion, including the articular pedicle, was performed and confirmed through histopathological analysis. Postoperative management included intensive motor rehabilitation, with satisfactory functional recovery observed over a five-month period. This case highlights the importance of early diagnosis and high clinical suspicion in patients presenting with acute lower limb weakness, as well as the need for prompt surgical intervention to prevent permanent neurological sequelae.

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