Compressive peroneal neuropathy by an intraneural ganglion cyst combined with L5 radiculopathy

Abstract

Rationale: Most cases of foot drop are known to result from lower motor neuron pathologies, particularly lumbar radiculopathy and peripheral neuropathy, including common peroneal neuropathy. To improve the prognosis of foot drop, it is important to quickly and accurately diagnose the etiology and provide appropriate treatment. Patient concerns: A 65-year-old female patient with a history of L4-5 intervertebral disc herniation presented with right foot drop that had developed 1 month previously. Diagnosis: Electrodiagnostic examination revealed common peroneal neuropathy combined with L5 radiculopathy, with the former being the main cause of the foot drop. MRI of the right knee was performed to identify the cause of the peroneal nerve lesion, which revealed an intraneural ganglion cyst in the common peroneal nerve. Interventions: The patient was treated by ultrasound-guided percutaneous cyst aspiration and corticosteroid injection into the decompressed ganglion, followed by strengthening exercise, electrical stimulation therapy, and prescription of an ankle foot orthosis. Outcomes: We confirmed regeneration of the injured peroneal nerve at the follow-up electrodiagnostic examination 12 weeks after the intervention. In addition, the manual motor power test demonstrated an increase in the ankle dorsiflexor function score by one grade. Lessons: Diagnosing the cause of foot drop can be difficult with multiple co-existing pathologies, and consideration of various possible etiologies is the key for appropriate diagnosis and treatment. In addition to imaging modalities such as MRI, electrodiagnostic examination can help to improve diagnostic accuracy. Intraneural ganglion cyst of the common peroneal nerve is rare, but should be considered as a possible cause of foot drop.

Peroneal neuropathy caused by an extraneural ganglion cyst in the supracondylar area of the femur

“…Table 2 summarizes case reports of the cyst around knee that were previously reported according to the classification. [ 10 , 11 , 14 , 16 , 19 – 23 ] To our knowledge, our case is the first report of compressive peroneal neuropathy caused by extraneural type of ganglion cyst in the supracondylar area of femur. Ganglion cyst compressions of the peroneal nerve can be classified as intraneural or extraneural lesions.…”

“…Moreover, a few studies have reported the development of peroneal neuropathy caused by intraneural-type cysts formed in the popliteal fossa. [ 16 , 17 ] To the best of our knowledge, no reports have described a case of common peroneal neuropathy caused by an extraneural ganglion cyst located at the proximal site of popliteal fossa.…”

Findings of Electrodiagnostic Studies in Moderate to Severe Lumbar Central Spinal Stenosis—Electrodiagnostic Studies in Lumbar Central Spinal Stenosis

“…L5 is the most frequently affected nerve root in LCSS. Peroneal and tibial nerves receive a significant contribution of fibers from this root and thus constitute a suitable target for NCS [ 18 ]. Since LCSS provokes a focal injury on the nerve, Wallerian degeneration can occur distally, which seems to contribute to the lowered amplitude of CMAPs of peroneal and tibial nerves [ 19 ].…”

An Update on Peroneal Nerve Entrapment and Neuropathy

“…CPN compression secondary to a cystic tibiofibular joint was reported in various cases. 41,[43][44][45] Two such cases described CPN compression due to intraneural ganglion and synovial cysts. 41,45 Complete return of motor function was accomplished via cyst aspiration in one case, while the other was treated with prompt surgical cyst removal and nerve decompression.…”

“…41,45 Complete return of motor function was accomplished via cyst aspiration in one case, while the other was treated with prompt surgical cyst removal and nerve decompression. 43,44 Two other reports of cystic etiologies included an extraneural popliteal cyst and two cases of children with extraneural tibiofibular joint synovial cysts, all of which were treated with surgical cyst removal and CPN decompression. 45,46 CPN compression due to bony growths were also commonly reported in multiple case reports.…”