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

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.

Magnetic Resonance Neurography of the Foot and Ankle

Peripheral neuropathies of the foot and ankle can be challenging to diagnose clinically due to concomitant traumatic and nontraumatic or degenerative orthopedic conditions. Although clinical history, physical examination, and electrodiagnostic testing comprised of nerve conduction velocities and electromyography are used primarily for the identification and classification of peripheral nerve disorders, MR neurography (MRN) can be used to visualize the peripheral nerves as well as the skeletal muscles of the foot and ankle for primary neurogenic pathology and skeletal muscle denervation effect. Proper knowledge of the anatomy and pathophysiology of peripheral nerves is important for an MRN interpretation.

An update on imaging of tarsal tunnel syndrome

Tarsal tunnel syndrome (TTS) is an entrapment neuropathy of the tibial nerve (TN) within the tarsal tunnel (TT) at the level of the tibio-talar and/or talo-calcaneal joints. Making a diagnosis of TTS can be challenging, especially when symptoms overlap with other conditions and electrophysiological studies lack specificity. Imaging, in particular MRI, can help identify causative factors in individuals with suspected TTS and help aid surgical management. In this article, we review the anatomy of the TT, the diagnosis of TTS, aetiological factors implicated in TTS and imaging findings, with an emphasis on MRI.

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.

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.

Ultrasound facilitates the diagnosis of tarsal tunnel syndrome: intraneural ganglion cyst of the tibial nerve

The tibial nerve intraneural ganglion cyst-which presents with fluid accumulated inside the nerve epineurium-is a rare etiology of tarsal tunnel syndrome. We report a case with insidious onset of numbness over his left medial ankle. Ultrasound imaging revealed that the tibial nerve was encircled by crescent-shaped anechoic substances, spanning from the distal leg to the sole. Magnetic resonance imaging disclosed a thickened tibial nerve wrapped by hyperintense materials in the tarsal tunnel. Some effusion was observed besides the tibialis posterior and flexor digitorum tendons as well. The patient underwent a surgical treatment and an intraneural ganglion cyst was confirmed. This report elaborated the clinical and imaging presentations of a tibial nerve intraneural ganglion cyst and highlighted the usefulness of ultrasound in exploring the cause of compressive neuropathy at the ankle region.

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.

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

Intraneural ganglion cysts in the tarsal tunnel are rare. We present a patient who had an intraneural ganglion cyst involving the medial and lateral plantar and distal tibial nerves. Magnetic resonance imaging revealed evidence to support the joint-related (i.e., subtalar) origin of the cyst. Careful reinterpretation of the imaging supported a phasic mechanism (i.e., cross-over) to explain the interrelated pathogenesis of the intraneural cyst within the three nerves. This mechanism is analogous to that described for the prototypes-the peroneal, tibial and sciatic nerves in the knee region-and can be generalized to other nerves in the foot and ankle region. We believe that understanding the pathogenesis sheds light on the effective treatment.

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.

Intraneural ganglion cysts: a systematic review and reinterpretation of the world's literature

OBJECTIVE The etiology of intraneural ganglion cysts has been controversial. In recent years, substantial evidence has been presented to support the articular (synovial) theory for their pathogenesis. The authors sought to 1) perform a systematic review of the world's literature on intraneural cysts, and 2) reinterpret available published MR images in articles by other authors to identify unrecognized joint connections. METHODS In Part 1, all cases were analyzed for demographic data, duration of symptoms, the presence of a history of trauma, whether electromyography or nerve conduction studies were performed, the type of imaging, surgical treatment, presence of a joint connection, intraneural cyst recurrence, and postoperative imaging. Two univariate analyses were completed: 1) to compare the proportion of intraneural ganglion cyst publications per decade and 2) to assess the number of recurrences from 1914 to 2003 compared with the years 2004-2015. Three multivariate regression models were used to identify risk factors for intraneural cyst recurrence. In Part 2, the authors analyzed all available published MR images and obtained MR images from selected cases in which joint connections were not identified by the original authors, specifically looking for unrecognized joint connections. Two univariate analyses were done: 1) to determine a possible association between the identification of a joint connection and obtaining an MRI and 2) to assess the number of joint connections reported from 1914 to 2003 compared with 2004 to 2015. RESULTS In Part 1, 417 articles (645 patients) were selected for analysis. Joint connections were identified in 313 intraneural cysts (48%). Both intraneural ganglion cyst cases and cyst recurrences were more frequently reported since 2004 (statistically significant difference for both). There was a statistically significant association between cyst recurrence and percutaneous aspiration as well as failure to disconnect the articular branch or address the joint. In Part 2, the authors identified 43 examples of joint connections that initially went unrecognized: 27 based on their retrospective MR image reinterpretation of published cases and 16 of 16 cases from their sampling of original MR images from published cases. Overall, joint connections were more commonly found in patients who received an MRI examination and were more frequently reported during the years 2004 to 2015 (statistically significant difference for both). CONCLUSIONS This comprehensive review of the world's literature and the MR images further supports the articular (synovial) theory and provides baseline data for future investigators.

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.

Peripheral neuropathy caused by joint-related cysts: a review of 17 cases

BACKGROUND

Clinical compression neuropathy caused by para-articular cysts is rare. Only recently, the unifying articular theory was proposed to clarify its true etiologic nature. The authors attribute 17 cases to this theory in order to illustrate the shift in the diagnostic and treatment protocol, and the possible impact on patient outcome.

METHODS

Eight intraneural and nine extraneural cysts were included. The proposed diagnostic protocol includes electromyography and ultrasound, followed by magnetic resonance imaging to characterize the cyst. The proposed treatment protocol consists of (1) ligation of the pedicle connecting the cyst with the afflicted joint, (2) decompression of the nerve and, when needed and (3) disarticulation of the superior tibiofibular joint (in case of peroneal nerve involvement).

RESULTS

Outcome was good to excellent in all patients, with recovery of sensory and motor function. Cyst recurrence was observed in three intraneural cases (18 %). Analysis of our own diagnostic protocol showed that atypical compression neuropathies should follow a strict diagnostic protocol to exclude missing the presence of a cyst. Ultrasound needs to play a crucial role, with MRI for cyst characterization and pedicle identification.

CONCLUSIONS

Retrospective proof in favor of the articular theory was found in all cases. An explanation for the cyst recurrences was formed based on the articular theory. In addition, a diagnostic and therapeutic protocol is proposed for all atypical peripheral compression neuropathies with the ultimate goal to achieve optimal patient outcome.

Clinical utility of tibial motor and sensory nerve conduction studies with motor recording from the flexor hallucis brevis: a methodological and reliability study

Background

Standard tibial motor nerve conduction measures are established with recording from the abductor hallucis. This technique is often technically challenging and clinicians have difficulty interpreting the information particularly in the short segment needed to assess focal tibial nerve entrapment at the medial ankle as occurs in posterior tarsal tunnel syndrome. The flexor hallucis brevis (FHB) has been described as an alternative site for recording tibial nerve function in those with posterior tarsal tunnel syndrome. Normative data has not been established for this technique. This pilot study describes the technique in detail. In addition we provide reference values for medial and lateral plantar orthodromic sensory measures and assessed intrarater reliability for all measures.

Methods

Eighty healthy female participants took part, and 39 returned for serial testing at 4 time points. Mean values ± SD were recorded for nerve conduction measures, and coefficient of variation as well as intraclass correlation coefficients (ICC) were calculated.

Results

Motor latency, amplitude and velocity values for the FHB were 4.1 ± 0.9 msec, 8.0 ± 3.0 mV and 45.6 ± 3.4 m/s, respectively. Sensory latencies, amplitudes, and velocities, respectively, were 2.8 ± 0.3 msec, 26.7 ± 10.1 μV, and 41.4 ± 3.5 m/s for the medial plantar nerve and 3.2 ± 0.5 msec, 13.3 ± 4.7 μV, and 44.3 ± 4.0 msec for the lateral plantar nerve. All values demonstrated significant ICC values (P ≤ 0.007).

Conclusion

Motor recording from the FHB provides technically clear waveforms that allow for an improved ability to assess tibial nerve function in the short segments used to assess tarsal tunnel syndrome. The reported means will begin to establish normal values for this technique.

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.

Tibial intraneural ganglia at the ankle and knee: incorporating the unified (articular) theory in adults and children

OBJECT

The etiology of intraneural ganglia has been debated for centuries, and only recently a unifying theory has been proposed. The incidence of tibial nerve intraneural ganglia is restricted to the occasional case report, and there are no reported cases of these lesions in children. While evidence of the unifying theory for intraneural ganglia of the common peroneal nerve is strong, there are only a few reports describing the application of the theory in the tibial nerve. In this report the authors examine tibial nerve intraneural ganglia at the ankle and knee in an adult and a child, respectively, and describe the clinical utility of incorporating the unifying (articular) theory in the management of tibial intraneural ganglia in adults and children.

METHODS

Cases of tibial intraneural ganglion cysts were examined clinically, radiologically, operatively, and histologically to demonstrate the application of the unified (articular) theory for the development of these cysts in adults and children.

RESULTS

Two patients with intraneural ganglion cysts of the tibial nerve were identified: an adult with an intraneural ganglion cyst of the tibial nerve at the tarsal tunnel and a child with an intraneural ganglion cyst of the tibial nerve at the knee. In each case, preoperative MR imaging demonstrated the intraneural cyst and its connection to the adjacent joint via the articular branch to the subtalar joint and superior tibiofibular joint. At surgery the articular branch was identified and resected, thus disconnecting the tibial nerve intraneural cyst from the joint of origin.

CONCLUSIONS

These cases detail the important features of intraneural ganglion cysts of the tibial nerve and document the clinical utility of incorporating the unifying (articular) theory for the surgical management of tibial intraneural ganglia in adults and children.

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.

Pseudotumoral ganglion cyst of a finger with unexpected remote origin: multimodality imaging

The case of a ganglion cyst in the pulp of a fifth finger in an elderly woman initially mimicking a soft tissue tumor is described. Most typical sites of ganglion cysts are well documented at the wrist and in the vicinity of inter-phalangeal and metacarpo-phalangeal joints. In this case, ultrasonography (US) and magnetic resonance imaging (MRI) demonstrated a cystic lesion within the pulp of the fifth finger and indicated carpal osteoarthritis as the distant-and unexpected-origin of the lesion. The suggested diagnosis of ganglion cyst was confirmed by computed tomography arthrography (CT arthrography) of the wrist, which showed opacification of the cyst on delayed acquisitions after intra-articular injection into the mid-carpal joint, through the fifth flexor digitorum tendon sheath. The communications between the degenerative carpal joint, the radio-ulnar bursa, the fifth flexor digitorum tendon sheath and the pedicle of the cyst were well demonstrated.

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.

MRI of peripheral nerves

MRI has become the modality of choice for imaging the peripheral nervous system. When technically optimized and customized for individual clinical problems, MRI can provide insight into the underlying causes of neoplastic, inflammatory, and other diseases affecting peripheral nerves with a high degree of accuracy and effectively distinguish benign from malignant processes. With high-resolution imaging techniques targeted fascicular biopsy can be planned to improve diagnostic yield and decrease the risk of surgically sampling primary nerve pathology.

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.

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.

Peroneal intraneural ganglia. Part I. Techniques for successful diagnosis and treatment

The common peroneal nerve is the peripheral nerve most often affected by intraneural ganglion cysts. Although the pathogenesis of these cysts has been the subject of controversy in the literature, it is becoming increasingly evident that they are of articular origin. Recent recognition of this fact has proven to be significant in reducing recurrences and improving treatment outcomes for patients. The authors present a stepwise method of assessing and treating peroneal intraneural ganglion cysts.

Peroneal intraneural ganglia

✓The authors describe common modes of failure in the diagnosis and treatment of patients with peroneal intraneural ganglia. Illustrated examples correlate the modes of failure and the diagnostic or surgical errors. Understanding these pitfalls reinforces the rationale behind current treatment recommendations as outlined in the companion article. Avoiding these pitfalls will ultimately improve outcomes.