Intraneural ganglion cyst of the peroneal nerve occurring after coronavirus disease-19 vaccination: A case report

Ganglion cysts are relatively common, but intraneural ganglion cysts (INGCs) within peripheral nerves are rare and poorly understood. We present the case of a 58-year-old woman who presented with acute right-foot drop. She experienced acute knee pain radiating from the lateral leg to the dorsal foot two days after the first coronavirus disease-19 (COVID-19) vaccination (BNT162b2, Pfizer-BioNTech). She had no history of trauma or medication use. Two weeks after the onset of symptoms, she developed a dorsiflexor weakness of the right foot (Medical Research Council grade, poor). The weakness worsened to a "trace" grade despite providing conservative management for one month. Ultrasonography revealed a fusiform echolucent structure within the course of the right common peroneal nerve around the fibular head. Magnetic resonance imaging revealed multiple intraneural cysts within the right common peroneal nerve. Nerve conduction and electromyographic studies revealed multiphasic motor unit action potentials accompanied by abnormal spontaneous activities in the innervated muscles, along with axonal degeneration of the deep peroneal nerves. Surgical removal of the cyst was performed, and the patient's symptoms gradually improved. Pathological examination revealed a cystic structure containing mucinous or gelatinous fluid and lined with flattened or cuboidal cells. The clinical course and sequential electromyographic findings relevant to this symptomatic cyst were temporally related to the vaccination date. The present case suggests that INGC-induced peroneal palsy is a possible complication after COVID-19 vaccination.

Can acute radiculopathy be caused by upper lumbar hemorrhagic synovial cyst spinal compression in the elderly?

Introduction and importance

Acute radiculopathy caused by upper lumbar synovial cysts is rare. They generally present with a slow development of symptoms resulting from spinal canal involvement. Intracyst hemorrhagic synovial cysts are extremely uncommon and can manifest as radicular pain, radiculopathy or even cauda equina compression syndrome.

Case presentation

A 71-year-old woman with acute back and radicular leg pain presented with worsening symptoms after receiving 1 week of therapy to the left lower limb without trauma. Magnetic resonance imaging (MRI) showed a hemorrhagic synovial intracyst at L2-L3 on the front of the left inter-facet joint which was identified as the cause of the acute back pain and radiculopathy which required surgical removal. Post-surgery, the patient followed the rehabilitation program instructions and attended all scheduled follow-up visits. The patient was asymptomatic at the one-year follow-up.

Clinical discussion

Synovial cysts are commonly associated with degenerative changes that occur with aging, although the specific cause is unknown. Surgical removal of an upper lumbar synovial cyst gives better results than non-surgical treatments if the symptoms persist or recurrent.

Conclusion

For recurrent symptomatic upper lumbar spine synovial cysts (L2−L3), surgery is usually the best option. Surgical removal of an upper lumbar synovial cyst can result in full relief of acute symptoms and reduction of neurologic deficits.

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Intracyst hemorrhagic synovial cysts in the upper lumbar spine are extremely uncommon.

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Synovial cysts can manifest as radicular pain, radiculopathy or even cauda equina compression syndrome.

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Surgical removal of upper lumbar synovial cysts gives better results than non-surgical treatments.

An intraneural ganglion cyst of the ulnar nerve at the wrist: a case report and literature review

Background

Intraneural ganglion cysts of the ulnar nerve at the wrist are rare and poorly understood. We report a case of an intraneural ganglion cyst at the level of the wrist.

Case presentation: A 48-year-old man presented with the complaints of weakness for 6 months and serious aggravation for 1 month in his right hand. After examinations, including ultrasound, the patient was diagnosed with an intraneural ganglion cyst. Intraoperatively, with exposure of the ulnar nerve, we found that the intraneural ganglion cyst was at the level of Guyon’s canal and extended approximately 6 cm proximally. Postoperatively, sensation of the fingers was normal, but atrophy of his muscles and limited straightening of his ring and little fingers were similar to those preoperatively.

Conclusions

Diagnosis of an intraneural cyst before surgery is mostly based on ultrasound and magnetic resonance imaging. Transection of the articular branch is an important measure to prevent recurrence of this cyst. If the ulnar nerve is compressed and causes symptoms, nerve decompression, including removal/aspiration of the cyst, and sometimes external neurolysis of the nerve, are necessary to relieve the symptoms and allow regeneration of the nerve. However, these should be performed without damaging the nerve fascicles.

Intraneural Ganglion as the Cause of Compression-Ischemic Lesion of Peroneal Nerve in Children

Two clinical cases of peroneal nerve lesion (patients 13 and 16 years) resulted from intraneural ganglion are presented. It is shown that only radical surgical intervention including resection of tibiofibular junction, removal of communicating canal and nerve decompression using cyst dissection (Spinner technique) could prevent ganglion relapse. In first patient completely lost peroneal nerve function was restored by musculotendinous transposition.

Microsurgical principles related to excision of intraneural ganglion at the elbow

We describe the treatment of a ganglion within the ulnar nerve at the elbow and apply the concept that an intraneural ganglion arises from the joint adjacent to the nerve in which the ganglion is located. Successful treatment of nerve compression and prevention of recurrence of the ganglion require disconnection of the nerve from the joint and deflation, not excision, of the ganglion.

Deep ulnar intraneural ganglia in the palm

BACKGROUND

While extraneural ganglion cysts are common and well known, intraneural ganglia are rare and misunderstood.

MATERIALS

We describe a patient with an intraneural ganglion in an unusual location, the deep branch of the ulnar nerve in the palm. We confirmed a connection to the triquetral-hamate joint on preoperative high-resolution MRI and intraoperatively, and observed distal extension of the cyst, a variant pattern of propagation. We wondered if these intraneural cysts followed the principles of the unifying articular (synovial) theory rather than the de novo (degenerative) theory suggested by others. We reviewed patients with ulnar intraneural ganglia at the wrist for joint connections and the pattern of propagation.

RESULTS

A total of 35 cases of ulnar intraneural ganglia at the wrist were identified, of which only 10 were joint connected. In 14 cases involving the deep ulnar branch, only 4 had joint connections. We hypothesized and proved that an unrecognized joint connection would be identified in the most recently reported case of a deep ulnar intraneural cyst in which a joint connection had not been identified. Propagation patterns supported descent in all cases involving the deep branch and proximal ascent in those of the main ulnar nerve (n = 18) or the dorsal cutaneous branch (n = 3). We believe that the orientation of the articular branches may play an important role in directionality in these intraneural cysts.

CONCLUSION

Contrary to popular opinion, our analysis of the literature would suggest that intraneural ganglia at this rare site obey the common principles of the articular theory described at more common sites for intraneural ganglia.

Sciatic nerve tumor and tumor-like lesions - uncommon pathologies

Sciatic nerve mass-like enlargement caused by peripheral nerve sheath tumors or neurocutaneous syndromes such as neurofibromatosis or schwannomatosis has been widely reported. Other causes of enlargement, such as from perineuroma, fibromatosis, neurolymphoma, amyloidosis, endometriosis, intraneural ganglion cyst, Charcot-Marie-Tooth disease, and chronic inflammatory demyelinating polyneuropathy are relatively rare. High-resolution magnetic resonance imaging (MRI) is an excellent non-invasive tool for the evaluation of such lesions. In this article, the authors discuss normal anatomy of the sciatic nerve and MRI findings of the above-mentioned lesions.