Tarsal tunnel syndrome caused by epineural ganglion of the posterior tibial nerve: report of 2 cases and review of the literature

Endoscopic Ganglionectomy of the Tarsal Tunnel: A Medial Approach

A ganglion inside the tarsal tunnel can compress the tibial nerve, leading to posterior tarsal tunnel syndrome. Classically, the ganglion is resected with an open approach. This requires release of the flexor retinaculum and dissection around the tibial neurovascular bundle, which may induce fibrosis around the tibial nerve. Endoscopic resection of a tarsal tunnel ganglion via a posterior approach has been reported. The purpose of this Technical Note is to describe the medial approach of endoscopic ganglionectomy of the tarsal tunnel. This is indicated for tarsal tunnel ganglia compressing the tibial nerve and extending to the flexor retinaculum. It is contraindicated if there is other pathology of the tarsal tunnel that demands open surgery; the ganglion compresses the tibial nerve from its deep side and does not extend to the flexor retinaculum; or in the presence of intraneural ganglion of the tibial nerve.

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.

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.

Tarsal Tunnel Syndrome Due To Three Different Types of Ganglion During a 12-Year Period: A Case Report

A 52-year-old male complained of numbness and radiating pain affecting the plantar region of his left foot. He was found to have recurrent tarsal tunnel syndrome due to posterior tibial nerve compression by 3 different types of ganglion during a 12-year period. To the best of our knowledge, a similar case has not been documented. At the first operation, flexor retinaculum release and simple excision of an epineural ganglion were performed without injuring the nerve fascicles; however, an intrafascicular ganglion developed approximately 2 years later. At the second operation, the ganglion cyst was resected completely to prevent recurrence, despite the risk of nerve fiber injury. The cyst originated from the subtalar joint; thus, the joint was closed, and a free fat graft was placed to prevent adhesion formation. However, an extraneural ganglion occurred about 3 years later. At the third operation, the cyst was resected completely, and a free periosteal graft was used to close the joint more effectively. No recurrence had developed at 6 years after the third operation. The findings of the present case show the need for long-term monitoring of patients with tarsal tunnel syndrome caused by a ganglion owing to the possibility of recurrence related to different ganglion types.

Endoscopic Resection of the Tarsal Tunnel Ganglion

The tarsal tunnel ganglion is a cause of posterior tarsal tunnel syndrome. Open resection of the ganglion calls for release of the flexor retinaculum and dissection around the tibial neurovascular bundle. This can induce fibrosis around the tibial nerve. We report the technique of endoscopic resection of the tarsal tunnel ganglion. It is indicated for tarsal tunnel ganglia arising from the adjacent joints or tendon sheaths and compressing the tibial nerve from its deep side. It is contraindicated if there is other pathology of the tarsal tunnel that demands open surgery; if the ganglion compresses the tibial nerve from its superficial side, which calls for a different endoscopic approach using the ganglion portal; or if an intraneural ganglion of the tibial nerve is present. The purpose of this technical note is to describe a minimally invasive approach for endoscopic resection of the tarsal tunnel ganglion.

Role of ultrasound in posteromedial tarsal tunnel syndrome: 81 cases

Posteromedial tarsal tunnel syndrome is a disorder affecting the tibial nerve or its branches. Diagnosis is established on the basis of physical examination and can be confirmed by electrophysiological evidence. However, diagnostic imaging is always required to identify the possible site of compression. High-resolution ultrasound (US) is playing an increasingly important role in the study of the nerves thanks to a series of advantages over magnetic resonance imaging, such as lower costs and widespread availability, high spatial resolution, fast examination using axial scans, dynamic and comparative studies, possibility of carrying out a study with the patient in the standing position, US Tinel sign finding, and the contribution of color/power Doppler US. We present the results obtained in a series of 81 patients who underwent US imaging between 2008 and 2013 due to posteromedial tarsal tunnel syndrome.

[Ultrasound of the tarsal tunnel: Normal and pathological imaging features]

Tarsal tunnel syndrome is a condition that is caused by compression of the tibial nerve or its associated branches. Diagnosis is based on clinical findings but imaging is performed to exclude a cause of compression, identified in 60 to 80% of cases. Ultrasound is a useful examination because of its high spatial resolution and ability to rapidly perform an axial survey of the nerves. The ultrasound imaging features of the tarsal tunnel are described. The etiologies and different types are illustrated through a review of clinical cases.

Intraneural ganglion of the superficial peroneal nerve: a case report

Ganglia affecting the peripheral nerves of the foot and ankle are rare. The most frequent location of occurrence is the common peroneal nerve at the level of the fibular neck. We report the case of an intraneural ganglion of the superficial peroneal nerve and its branches. Although there have been many previous reports of intraneural ganglion involvement with the common peroneal nerve, deep peroneal nerve, sural nerve, and the posterior tibial nerve, to our knowledge, this is the first reported occurrence of an intraneural ganglion distinctly localized to the superficial peroneal nerve and its branches. The presumptive diagnosis was made preoperatively using magnetic resonance imaging, and then confirmed postoperatively by pathologic examination. Despite the use of operative magnification, it was impossible to remove all of the cyst elements within the nerve trunk, because the nerve fascicles were intimately intertwined. Therefore, complete resection of the common trunk of the superficial peroneal nerve and its terminal branches was performed, and the proximal stump was buried in a hole in the distal fibula. Two years after the surgery, the patient was pain free and asymptomatic except for cutaneous anesthesia in the distribution of the superficial peroneal nerve.

Value of computed tomography arthrography with delayed acquisitions in the work-up of ganglion cysts of the tarsal tunnel: report of three cases

Ganglion cysts are a common cause of tarsal tunnel syndrome. As in other locations, these cysts are believed to communicate with neighboring joints. The positive diagnosis and preoperative work-up of these cysts require identification and location of the cyst pedicles so that they may be excised and the risk of recurrence decreased. This can be challenging with ultrasonography and magnetic resonance (MR) imaging. We present three cases of symptomatic ganglion cysts of the tarsal tunnel, diagnosed by MR imaging, where computed tomography (CT) arthrography with delayed acquisitions helped to confirm the diagnosis and identify precisely the topography of the communication with the subtalar joint. These cases provide new evidence of the articular origin of ganglion cysts developing in the tarsal tunnel.

THE UNIFYING ARTICULAR (SYNOVIAL) ORIGIN OF INTRANEURAL GANGLIA

THE PATHOGENESIS OF intraneural ganglia has been an issue of curiosity, controversy, and contention for 200 years. Three major theories have been proposed to explain their existence, namely, 1) degenerative, 2) synovial (articular), and 3) tumoral theories, each of which only partially explains the observations made by a number of investigators. As a result, differing operative strategies have been described; these generally meet with incomplete neurological recoveries and high rates of recurrence. Recent advances in magnetic resonance imaging and critical analysis of the literature have clarified the mechanisms underlying the formation and propagation of these cysts, thereby confirming the unifying articular (synovial) theory. By identifying the shared features of the typical cases and explaining atypical examples or clinical outliers, several fundamental principles have been described. These include: 1) a joint origin; 2) dissection of fluid from that joint along an articular nerve branch, extension occurring via a path of least resistance; and 3) cyst size, extent, and directionality being influenced by pressures and pressure fluxes. We believe that understanding the pathogenesis of these cysts will be reflected in optimal surgical approaches, improved outcomes, and decreased frequency, if not elimination, of recurrences. This article describes the ongoing process of critically analyzing and challenging previous observations and evidence in an effort to prove a concept and a theory.

Short-term operative outcome of tarsal tunnel syndrome due to benign space-occupying lesions

BACKGROUND

It has been reported that the operative outcome of tarsal tunnel syndrome caused by space-occupying lesions is more favorable than those caused by other reasons. The purpose of this clinical study was to report our clinical results after surgical treatment for tarsal tunnel syndrome caused by benign space-occupying lesions.

MATERIALS AND METHODS

From July 2004 to February 2007, 20 patients underwent surgical decompression for tarsal tunnel syndrome in our institution. Out of them, 13 cases were due to space-occupying lesions around the tarsal tunnel. The average age was 51.3 and the mean symptom duration was 16.5 months. The operation included complete release of the tarsal tunnel and removal of the space-occupying lesion. The clinical outcomes measured were a pain visual analogue scale (VAS), AOFAS score and the degree of subjective satisfaction.

RESULTS

Ganglion was the most frequent cause (10 cases). Other pathologies included synovial chondromatosis, a Schwannoma and a talocalcaneal coalition. There was a significant improvement after surgery in term of VAS (6.4/2.2) and AOFAS score (77.8/92.7). Seven of 13 were satisfied with the results, three felt they had a fair result, and three were dissatisfied.

CONCLUSION

Though significant improvement was found in the average VAS and AOFAS score, subjective satisfaction was less favorable (54%) than expected. We believe surgeons should be more cautious concerning outcomes when expectations of surgery are discussed with patients.

Magnetic resonance imaging of a deep peroneal intraneural ganglion cyst originating from the second metatarsophalangeal joint: a pattern of propagation supporting the unified articular (synovial) theory for the formation of intraneural ganglia

A deep peroneal intraneural cyst of the first web space of the foot is presented. Analysis of the magnetic resonance image scans revealed not only a connection with the medial aspect of the second metatarsophalangeal joint, but also the presence of an interconnected cyst within the lateral digital branch of the hallux. These characteristic magnetic resonance image findings are consistent with those previously described for a peroneal intraneural ganglion cyst that arose from the superior tibiofibular joint, and include (1) origin (ascent) from the second metatarsophalangeal joint with propagation along the articular branch and into the dorsal digital branch of the second toe, (2) cross-over within the shared epineurial sheath of the deep peroneal nerve, and (3) further propagation (descent) within the dorsal digital branch of the hallux. The analogous features between intraneural ganglion cysts affecting small and large-caliber nerves support the fundamental principles of the unified articular (synovial) theory for the formation of intraneural ganglia, including (1) a connection to a synovial joint, (2) dissection of joint fluid through a capsular rent along the articular branch into the parent nerve, and (3) intra-epineurial, pressure-dependent propagation of cyst fluid along paths of least resistance.

LEVEL OF CLINICAL EVIDENCE

4.

Tarsal tunnel syndrome associated with a neurilemoma in posterior tibial nerve: a case report

Compression neuropathy of the posterior tibial nerve (PTN) and its branches in the tarsal tunnel is called tarsal tunnel syndrome (TTS) and has various aetiologies. Space-occupying lesions in the tunnel, such as neurilemomas, can cause such a disease. When a neurilemoma occupies the tarsal tunnel, it can compress the PTN directly or indirectly and results in restriction of the tunnel volume. Symptoms due to this restricted volume may vary in TTS. A case of neurilemoma of PTN in tarsal tunnel with a complaint of posteromedial ankle intermittent pain in a 20-year-old patient is presented here. A mass was observed at the ankle posteromedially during clinical examinations and the patient underwent magnetic resonance imaging (MRI) and radiological investigation. Radiographic evaluation of the ankle was normal. However, MRI was revealed a mass adjacent to the PTN in the tarsal tunnel. An ovoid, smooth-surfaced, encapsulated and eccentrically localized mass in the PTN was detected at surgery. The mass was excised from the nerve and pathological evaluation revealed a neurilemoma (schwannoma). Neurilemomas arising from the PTN in the tarsal tunnel should always be kept in mind as a differential diagnosis when a patient complains of a posteromedial ankle pain. Since it is a space-occupying lesion and encapsulated tumor in the tarsal tunnel, simple surgical resection is curative without a distinct morbidity.

A posttraumatic, joint-connected sural intraneural ganglion cyst-with a new mechanism of intraneural recurrence: a case report

Intraneural ganglion cysts are rare in occurrence and most commonly involve the peroneal nerve at the fibular neck. We present a case of a traumatically induced intraneural ganglion cyst of the sural nerve that developed after a nondisplaced posterior malleolus ankle fracture. The intraneural ganglion cyst was connected to the subtalar joint by its articular branch and ascended several centimeters into the distal fourth of the leg. It was resected from the sural nerve proper and the posterior branch of the lateral calcaneal nerve, and the articular trunk was ligated. The patient developed subclinical intraneural recurrence, which was detected on a postoperative magnetic resonance imaging (MRI). Retrospective reinterpretation of the preoperative and postoperative MRIs revealed that ligation of the articular trunk proximal to a major branch (ie, the anterior branch of the lateral calcaneal nerve) led to increased intraneural cyst propagation distally: within the blind stump of the articular trunk and within several anterior branches of the lateral calcaneal nerve but not within the parent sural nerve or its continuation, the lateral dorsal cutaneous nerve. This mode of intraneural, but extraparental nerve recurrence can be easily understood by considering the altered fluid dynamics, particularly the increased resistance. This case report provides further evidence not only supporting the articular theory of intraneural ganglion formation but also highlighting the importance of searching for, identifying, and treating the pathologic articular branch connection near its joint connection in all cases.

LEVEL OF CLINICAL EVIDENCE

4.

Epineurial compartments and their role in intraneural ganglion cyst propagation: An experimental study

New patterns of intraneural ganglion cyst formation are emerging that have not previously been explained in current pathoanatomic terms. We believe there are three important elements underlying the appearance of these cysts: (a) an articular branch of the nerve that connects to a nearby synovial joint; (b) ejected synovial fluid following the path of least resistance along tissue planes; and (c) the additional effects of pressure and pressure fluxes. The dynamic nature of cyst formation has become clearly apparent to us in our clinical, operative and pathologic practice, but the precise mechanism underlying the process has not been critically studied. To test our hypothesis that a fibular (peroneal) or tibial intraneural cyst derived from the superior tibiofibular joint could ascend proximally into the sciatic nerve, expand within it and descend into terminal branches of this major nerve, we designed a series of simple, qualitative laboratory experiments in two cadavers (four specimens, six experiments). Injecting dye into the outer or "epifascicular" epineurium of the fibular and the tibial nerves we observed its ascent, cross over and descent patterns in three of three specimens as well as its cross over after an outer epineurial sciatic injection. In contrast, injecting dye into the inner or "interfascicular" epineurium led to its ascent within the tibial nerve and its division within the sciatic nerve in one specimen and lack of cross over in a sciatic nerve injection. Histologic cross-sections of the nerves at varying levels demonstrated a tract of disruption within the outer epineurium of the nerve injected and the nerve(s) into which the dye, after cross over, descended. Those specimens injected in the inner epineurium demonstrated dye within this tract but without disruption of or dye intrusion into the outer epineurium. In no case did the dye pass through the perineurial layers. Coupled with our observations in previous detailed studies, these anatomic findings provide proof of concept that sciatic cross over occurs due to the filling of its common epineurial sheath; furthermore, these findings, support the unifying articular theory, even in cases wherein patterns of intraneural ganglion cyst formation are unusual. Additional work is needed to be done to correlate these anatomic findings with magnetic resonance imaging and surgical pathology.

Peroneal and tibial intraneural ganglia: correlation between intraepineurial compartments observed on magnetic resonance images and the potential importance of these compartments

Object

Previously the authors demonstrated that peroneal and tibial intraneural ganglia arising from the superior tibiofibular joint may occasionally extend proximally within the epineurium to reach the sciatic nerve. The dynamic nature of these cysts, dependent on intraarticular pressures, may give rise to differing clinical and imaging presentations that have remained unexplained until now. To identify the pathogenesis of these unusual cysts and to correlate their atypical magnetic resonance (MR) imaging appearance, the authors retrospectively reviewed their own experience as well as the published literature on these types of intraneural ganglia.

Methods

A careful review of MR images obtained in 22 patients with intraneural ganglia located about the knee region (18 peroneal and four tibial intraneural ganglia) allowed the authors to substantiate three different patterns: outer (epifascicular) epineurial (20 cases); inner (interfascicular) epineurial (one case); and combined outer and inner epineurial (one case). In these cases serial MR images allowed the investigators to track the movement of the cyst within the same layer of the epineurium. All lesions had connections to the superior tibiofibular joint. Nine patients were identified as having lesions with sciatic nerve extension. Seven patients harboring an outer epineurial cyst (six in whom the cyst involved the peroneal nerve and one in whom it involved the tibial nerve) had signs of sciatic nerve cross-over, with the cyst seen in the sciatic nerve and/or other terminal branches. In only two of these cases had the cyst previously been recognized to have sciatic nerve involvement. In contrast, in one case an inner epineurial cyst involving the tibial nerve ascended within the tibial division of the sciatic nerve and did not cross over. A single patient had a combination of both outer and inner epineurial cysts; these were easily distinguished by their distinctive imaging patterns.

Conclusions

This anatomical compartmentalization of intraneural cysts can be used to explain varied clinical and imaging patterns of cleavage planes for cyst formation and propagation. Compartmentalization elucidates the mechanism for cases of outer epineurial cysts in which there are primary ascent, sciatic cross-over, and descent of the lesion down terminal branches; correlates these cysts' atypical MR imaging features; and contrasts a different pattern of inner epineurial cysts in which ascent and descent occur without cross-over. The authors present data demonstrating that the dynamic phases of these intraneural ganglia frequently involve the sciatic nerve. Their imaging features are subtle and serve to explain the underrecognition and underreporting of the longitudinal extension of these cysts. Importantly, cysts extending to the sciatic nerve are still derived from the superior tibiofibular joint. Combined with the authors' previous experimental data, the current observations help the reader understand intraneural ganglia with a different, deeper degree of anatomical detail.

Tibial intraneural ganglia in the tarsal tunnel: Is there a joint connection?

Intraneural ganglia are rare entities, and, as such, their pathogenesis has been extremely controversial. Recent evidence from intraneural ganglia occurring at more proximal sites-the peroneal nerve at the fibular neck (the most common site) and the tibial nerve at the knee-has suggested an articular origin rather than de novo formation. To our knowledge, of the 10 previous reports of tibial intraneural ganglia within the tarsal tunnel by others, a joint connection to the ankle joint was only identified in 2 cases. To support a hypothesis that tibial intraneural ganglia occurring within the tarsal tunnel region arise from neighboring joints, we analyzed 3 patients retrospectively, all of whom had magnetic resonance (MR) imaging and operative intervention. One of these patients was treated by a peripheral nerve surgeon specializing in foot and ankle surgery. The other 2 patients were the only ones previously published in the literature who had MR images available for reinterpretation. In none of these cases was a joint communication appreciated by radiologists interpreting the MR images preoperatively or by surgeons intraoperatively. Our review of these same cases demonstrated radiographic evidence of joint communications with the subtalar joints. Based on our findings in this article and our knowledge of intraneural ganglia occurring at more proximal sites, we believe that tibial intraneural ganglia within the tarsal tunnel originate from neighboring joints and that their connections to the joints (pedicles) are through articular branches. The importance of these connections is 2-fold: first, for their role in the pathogenesis of this entity, and second, for their potential therapeutic implications. As is highlighted by the clinical and radiographic follow-up in the 1 patient in this article and in many previously reported at other sites, intraneural cyst recurrence can occur if surgeons do not specifically address the articular connection.