The mechanism underlying combined medial and lateral plantar and tibial intraneural ganglia in the tarsal tunnel

Huge Intraneural Ganglion Cyst of Tibial Nerve in a 78-Year-Old Male Patient With Gonarthrosis: A Case Report and Review of the Literature

Intraneural ganglion cysts (IGCs) are mucinous cysts located within peripheral nerves, often associated with an articular nerve branch and the adjacent synovial joint capsule. These cysts, while rare, can occur in various nerves, with the tibial nerve being an infrequent site. Tibial nerve IGCs are rare pathologies. We present a case of a tibial nerve IGC in a 78-year-old male patient with pre-existing grade III gonarthrosis. Furthermore, we performed a brief review of the existing literature for tibial nerve IGCs. To our knowledge, we present the second case of an IGC in a patient with known pre-existing gonarthrosis. This case raises the potential association between IGCs and degenerative knee pathologies and underscores the crucial role of early and accurate diagnosis. Differential diagnosis of nerve sheath tumors and extra-articular calf neuropathy is essential not only for definitive treatment but also to rule out more serious alternative diagnoses. While ultrasound-guided aspiration of cystic fluid with steroid injection and conservative management are also treatment methods defined in the literature, we believe that exploratory surgery is the critical point of treatment. Early and accurate diagnosis is paramount, as delayed diagnosis and treatment may cause persistent functional and sensory deficits.

Tarsal tunnel ganglion cyst: intraneural or extraneural site?

Intraneural ganglion cysts are very uncommon lesions, whose diagnosis has increased since the articular theory and the description of the MRI findings were established. We present a case report of a 59-year-old man with symptoms of tarsal tunnel syndrome. Foot and ankle MRI demonstrated the presence of an intraneural cystic lesion in the posterior tibial neve and its connection with the subtalar joint through an articular branch. The identification of the specific radiological signs like the «signet ring sign» allowed establishing an adequate preoperative diagnosis, differentiating it from an extraneural lesion and facilitating the articular disconnection of the nerve branch during surgery.

The medial safe zone for treating intraneural ganglion cysts in the tarsal tunnel: a technical note

INTRODUCTION

Intraneural ganglion cysts in the tarsal tunnel are rare but are being increasingly reported. The cysts involve the tibial or plantar nerves and are most commonly derived from a neighboring (degenerative) joint, (i.e., the tibiotalar or subtalar) via an articular branch arising from the medial aspect of the nerve. We describe a safe zone for approaching these cysts in the tarsal tunnel that allows for identification of the joint connection without injury to important distal branches.

METHODS

We present a case of an intraneural ganglion cyst within the tarsal tunnel in a patient with symptoms consistent with tarsal tunnel syndrome. Using intraoperative photographs and artist rendering, we describe a technique to safely disconnect the abnormal joint connection while preserving the important distal branches of the tibial nerve.

CONCLUSION

The safe zone for the tibial nerve in the tarsal tunnel can be exposed by mobilization and gentle retraction of the vascular bundle. In cases of intraneural ganglion cysts, all apparent connections between the nerve and degenerative joints within this safe zone can be resected without injury to important distal nerve branches.

A Case Report and Literature Review: Intraneural Ganglion Cyst Causing Tarsal Tunnel Syndrome

Intraneural ganglion cysts are benign mucinous lesions that form within joints and enter adjacent nerves via an articular branch. Despite being morphologically characterized as benign, they can demonstrate considerable intrafascicular destruction and expansion, resulting in worsening compressive neuropathies or nerve injury. There have been several suggested theories of pathogenesis, but the most widely accepted articular (synovial) theory describes a capsular defect in a neighboring joint that allows joint fluid to egress and track along the epineurium of the innervating articular branch. In this case report, we describe an intraneural ganglionic cyst located in the tarsal tunnel with extensive involvement of the tibial nerve. We describe the symptoms, diagnosis, and treatment as well as review the current literature on intraneural ganglionic cysts.

Degenerative subtalar joints complicated by medial plantar intraneural cysts : cutting the cystic articular branch prevents recurrence

AIMS

The pathogenesis of intraneural ganglion cysts is controversial. Recent reports in the literature described medial plantar intraneural ganglion cysts (mIGC) with articular branches to subtalar joints. The aim of the current study was to provide further support for the principles underlying the articular theory, and to explain the successes and failures of treatment of mICGs.

PATIENTS AND METHODS

Between 2006 and 2017, five patients with five mICGs were retrospectively reviewed. There were five men with a mean age of 50.2 years (33 to 68) and a mean follow-up of 3.8 years (0.8 to 6). Case history, physical examination, imaging, and intraoperative findings were reviewed. The outcomes of interest were ultrasound and/or MRI features of mICG, as well as the clinical outcomes.

RESULTS

The five intraneural cysts followed the principles of the unifying articular theory. Connection to the posterior subtalar joint (pSTJ) was identified or suspected in four patients. Re-evaluation of preoperative MRI demonstrated a degenerative pSTJ and denervation changes in the abductor hallucis in all patients. Cyst excision with resection of the articular branch (four), cyst incision and drainage (one), and percutaneous aspiration/steroid injection (two) were performed. Removing the connection to the pSTJ prevented recurrence of mIGC, whereas medial plantar nerves remained cystic and symptomatic when resection of the communicating articular branch was not performed.

CONCLUSION

Our findings support a standardized treatment algorithm for mIGC in the presence of degenerative disease at the pSTJ. By understanding the pathoanatomic mechanism for every cyst, we can improve treatment that must address the articular branch to avoid the recurrence of intraneural ganglion cysts, as well as the degenerative pSTJ to avoid extraneural cyst formation or recurrence. Cite this article: Bone Joint J 2018;100-B:183-9.

Peroneal Nerve Palsy Due to Subparaneurial Ganglion Cyst, a Rare Variant of Intraneural Ganglion Cyst

Intraneural ganglion cysts are rare mucinous cysts originating within the epineurium of peripheral nerves. Although ganglion cysts are the most frequent tumors of the upper and lower extremities, ganglion cysts rarely result in peripheral nerve compression. We report a case of a 30-year-old patient who presented with foot drop due to subparaneurial ganglion cyst, a variant of an intraneural ganglion cyst. Characteristic magnetic resonance imaging findings were essential in the preoperative diagnosis of intraneural ganglion cyst. The common peroneal nerve and its branches were recognized and traced to its bifurcation during the operation. The articular branches were addressed. The mucious content of the ganglion was typically found to be located within the subparaneurial compartment. Incision of the subparaneurial ganglion cyst was performed, and mucinous content was evacuated. At 2 months after the surgery, paralyzed peroneal nerve was recovered completely. Therefore, early diagnosis of intraneural ganglion, precise identification of the pathology, and proper treatment of the articular branch with atraumatic dissection of ganglion cyst are essential in the successful management of this rare lesion.

Occult Isolated Articular Branch Cyst of the Lateral Plantar Nerve

We present the first known case of cyst fluid localized to an articular branch without involvement of the larger parent nerve. During a routine tarsal tunnel decompression in a patient with fluctuating plantar foot symptoms and "normal" magnetic resonance imaging findings, we identified cyst fluid within an articular branch of the lateral plantar nerve to the subtalar joint. Our incidental intraoperative discovery was corroborated by retrospective review of the magnetic resonance images. Although we do not know whether this cyst was responsible for the patient's complaints, we believe this finding represents a snapshot into the life cycle of intraneural ganglion cysts: either the "birth" of an ultra-early one or the remnant of a once larger one. Both interpretations are consistent with the unifying articular theory and add further insight into the dynamic phases of the progression of intraneural ganglion cysts.