Coexisting secondary intraneural and vascular adventitial ganglion cysts of joint origin: a causal rather than a coincidental relationship supporting an articular theory

Ganglion Cysts Arising From the Proximal Tibiofibular Joint: Treatment Approach and Associated Outcomes-A Systematic Review

Background: Proximal tibiofibular joint (PTFJ) ganglion cyst is a rare condition with a high rate of recurrence. Optimal treatment has not yet been determined. Purpose: We aimed to answer the following questions: (1) What are the most common treatments for PTFJ cysts and their associated recurrence rates? (2) What are the risk factors for failure to completely recover from symptoms? (3) What are the risk factors for cyst recurrence? Methods: A systematic review was performed using PubMed and EMBASE databases. Studies were assessed for inclusion and exclusion criteria, and quality analysis following the PRISMA guidelines. Information on demographic, clinical, and treatment characteristics was retrieved from articles. Results: The most common surgical treatment was cyst excision (75.3%). Patients with PTFJ arthrodesis and PTFJ resection had the lowest recurrence rates at 0% and 4.4%, respectively. Complete recovery from symptoms was more common in PTFJ resection (70.8%) than in PTFJ arthrodesis (42.9%). Risk factors for failure to achieve complete recovery from symptoms included intraneural compromise (odds ratio [OR] = 3.93), cyst recurrence (OR = 6.04), and being a contact sports athlete (OR = 9.85). Ligation of the articular branch of the peroneal nerve (PN) was a protective factor (OR = 0.29). A history of knee arthritis was the most important risk factor for cyst recurrence (OR = 20.01); PTFJ arthrodesis was a protective factor (OR = 0.04). Conclusion: This systematic review of level-IV studies found PTFJ resection or arthrodesis to be the most effective treatment options. Intraneural compromise of the common peroneal nerve, cyst recurrence, and participation in contact sports are risk factors for incomplete symptom recovery, and ligation of the articular branch of the PN is a protective factor. Knee arthritis is a risk factor for cyst recurrence. More rigorous study is needed.

Juxtaneural ganglia arising from the hip joint: focus on magnetic resonance imaging findings and clinical manifestations

OBJECTIVE

To present cases of juxtaneural ganglia arising from the hip with a discussion of the magnetic resonance imaging (MRI) findings, presenting symptoms, and possible treatment option.

MATERIALS AND METHODS

Two radiologists performed a consensus review of MRI scans obtained between January 2013 and March 2021 to identify patients with juxtaneural ganglia around the hip. A total of 11 patients with 11 juxtaneural ganglia were identified. Medical records and MRI findings were retrospectively reviewed.

RESULTS

Eight patients had lesions involving the sciatic nerve, and three patients had lesions involving the obturator nerve. Sciatic ganglia arose from a paralabral cyst in the posteroinferior quadrant and continued through a narrow channel running along the posterior acetabulum, showing increased diameter in the sciatic foramen and intrapelvic portion. Obturator ganglia showed a J- or reverse J-shape on the coronal imaging plane and extended from a paralabral cyst in the anteroinferior quadrant via the obturator canal. Nine patients (9/11, 81.8%) had symptoms resembling those of lumbosacral radiculopathy. Four patients underwent arthroscopic surgery, and one patient underwent ultrasound-guided aspiration, all of whom showed partial improvement. Spontaneous decrease in the extent of the ganglion was observed in three patients (3/11, 27.3%).

CONCLUSION

This article describes rare cases of juxtaneural ganglia arising from the hip joint and involving the sciatic and obturator nerves. The lesions share similar MRI findings, and each type of cyst (sciatic or obturator ganglia) involves a specific labral quadrant.

A novel mechanism for the formation and propagation of neural tumors and lesions through neural highways

By recognizing anatomic and radiologic patterns of rare and often misdiagnosed peripheral nerve tumors/lesions, we have defined mechanisms for the propagation of neural diseases. The novel concept of the nervous system serving as a complex system of "highways" driving the neural and perineural spread of these lesions is described in three examples: Intraneural dissection of joint fluid in intraneural ganglion cysts, perineural spread of cancer cells, and dissemination of unknown concentrations of neurotrophic/inhibitory factors for growth in hamartomas/choristomas of nerve. Further mapping of these pathways to identify the natural history of diseases, the spectrum of disease evolution, the role of genetic mutations, and how these neural pathways interface with the lymphatic, vascular, and cerebrospinal systems may lead to advances in targeted treatments.

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.

Recurrent intraneural ganglion cysts: Pathoanatomic patterns and treatment implications

The etiology of intraneural ganglion cysts has been poorly understood. This has resulted in the development of multiple surgical treatment strategies and a high recurrence rate. We sought to analyze these recurrences in order to provide a pathoanatomic explanation and staging classification for intraneural cyst recurrence. An expanded literature search was performed to identify frequencies and patterns in cases of intraneural ganglion cyst recurrences following primary surgery. Two univariate analyses were completed to identify associations between the type of revision surgery and repeat cyst recurrences. The expanded literature search found an 11% recurrence rate following primary surgery, including 64 recurrences following isolated cyst decompression (Group 1); six after articular branch resection (Group 2); and none following surgical procedures that addressed the joint (Group 3). Eight cases did not specify the type of primary surgery. In group 1, forty-eight of the recurrences (75%) were in the parent nerve, three involved only the articular branch, and one travelled along the articular branch in a different distal direction without involving the main parent nerve. In group 2, only one case (17%) recurred/persisted within the parent nerve, one recurred within a persistent articular branch, and one formed within a persistent articular branch and travelled in a different distal direction. Intraneural recurrences most commonly occur following surgical procedures that only target the main parent nerve. We provide proven or theoretical explanations for all identified cases of intraneural recurrences for an occult or persistent articular branch pathway.

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.

Median nerve neuropathy in the forearm due to recurrence of anterior wrist ganglion that originates from the scaphotrapezial joint: Case Report

Background

Median nerve neuropathy caused by compression from a tumor in the forearm is rare. Cases with anterior wrist ganglion have high recurrence rates despite surgical treatment. Here, we report the recurrence of an anterior wrist ganglion that originated from the Scaphotrapezial joint due to incomplete resection and that caused median nerve neuropathy in the distal forearm.

Case presentation

A 47-year-old right-handed housewife noted the appearance of soft swelling on the volar aspect of her left distal forearm, and local resection surgery was performed twice at another hospital. One year after the last surgery, the swelling reappeared and was associated with numbness and pain in the radial volar aspect of the hand. Magnetic resonance imaging revealed that the multicystic lesion originated from the Scaphotrapezial joint and had expanded beyond the wrist. Exploration of the left median nerve showed that it was compressed by a large ovoid cystic lesion at the distal forearm near the proximal end of the carpal tunnel. We resected the cystic lesion to the Scaphotrapezial joint. Her symptoms disappeared 1 week after surgery, and complications or recurrent symptoms were absent 13 months after surgery.

Conclusions

A typical median nerve compression was caused by incomplete resection of an anterior wrist ganglion, which may have induced widening of the cyst. Cases with anterior wrist ganglion have high recurrence rates and require extra attention in their treatment.

Extreme intraneural ganglion cysts

Object

The mechanism responsible for exceptional examples of intraneural ganglia with extensive longitudinal involvement has not been understood. Such cases of intraneural cysts, seemingly remote from a joint, have been thought not to have articular connections. Decompression and attempted resection of the cyst has led to intraneural recurrence and poor neurological recovery. The purpose of this report is not only to clarify the pathogenesis of these cysts, but also to discuss their treatment based on modern concepts of intraneural ganglia.

Methods

Two examples of extreme longitudinal propagation of intraneural ganglia are presented.

Results

A patient with a moderate tibial neuropathy was found to have a tibial intraneural ganglion. Prospective interpretation of the MR imaging study demonstrated the cyst's origin from the posterior portion of the superior tibiofibular joint (STFJ), with proximal extension within the sciatic nerve to the lower buttock region. Communication between the STFJ and the cyst was confirmed with direct knee MR arthrography. The tibial intraneural cyst was treated successfully by a relatively limited exposure in the distal popliteal fossa: the cyst was decompressed, the articular branch disconnected, and the STFJ resected. Postoperatively, the patient improved neurologically and there was no evidence of recurrent cyst on postoperative MR imaging. A second patient, previously reported by another group, was reexamined 22 years after surgery. This patient had an extensive peroneal intraneural ganglion that extended into the sciatic nerve from the knee to the buttock; no joint connection or recurrent cyst had initially been described. In this patient, the authors hypothesized and established with MR imaging the presence of both: a joint connection to the anterior portion of the STFJ from the peroneal articular branch as well as recurrent cyst within the peroneal and tibial nerves.

Conclusions

This paper demonstrates that extreme intraneural cysts are not clinical outliers but represent extreme examples of other more typical intraneural cysts. They logically obey the same principles, previously described in the unified articular (synovial) theory. The degree of longitudinal extension is probably due to high intraarticular pressures within the degenerative joint of origin. The generalizability of the mechanistic principles is highlighted by the fact that these 2 cases, involving the tibial and the peroneal nerve respectively, both extended well distant (that is, to the buttock) from the STFJ via their respective articular branch of origin. These extensive intraneural cysts can be treated successfully by disconnecting the affected articular branch and by resection of the joint of origin, rather than by a more aggressive operation resecting the cyst and cyst wall.

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.

Intraneural ganglia: a clinical problem deserving a mechanistic explanation and model

Intraneural ganglion cysts have been considered a curiosity for 2 centuries. Based on a unifying articular (synovial) theory, recent evidence has provided a logical explanation for their formation and propagation. The fundamental principle is that of a joint origin and a capsular defect through which synovial fluid escapes following the articular branch, typically into the parent nerve. A stereotypical, reproducible appearance has been characterized that suggests a shared pathogenesis. In the present report the authors will provide a mechanistic explanation that can then be mathematically tested using a preliminary model created by finite element analysis.

Sequential tibial and peroneal intraneural ganglia arising from the superior tibiofibular joint

We present a patient who developed a peroneal intraneural ganglion and an adventitial cyst following the incomplete treatment of a tibial intraneural ganglion. These separate cysts all originated from the superior tibiofibular joint and dissected along their respective articular branches. A logical mechanistic explanation for these coexisting cysts is provided, which highlights the shared pathogenesis--its joint-related nature--rather than a multifocal de novo process. These observations would not only be consistent with, but would extend previous evidence in support of, the unifying articular (synovial) theory.

Dynamic phases of peroneal and tibial intraneural ganglia formation: a new dimension added to the unifying articular theory

OBJECT

The pathogenesis of intraneural ganglia has been a controversial issue for longer than a century. Recently the authors identified a stereotypical pattern of occurrence of peroneal and tibial intraneural ganglia, and based on an understanding of their pathogenesis provided a unifying articular explanation. Atypical features, which occasionally are observed, have offered an opportunity to verify further and expand on the authors' proposed theory.

METHODS

Three unusual cases are presented to exemplify the dynamic features of peroneal and tibial intraneural ganglia formation.

RESULTS

Two patients with a predominant deep peroneal nerve deficit shared essential anatomical findings common to peroneal intraneural ganglia: namely, 1) joint connections to the anterior portion of the superior tibiofibular joint, and 2) dissection of the cyst along the articular branch of the peroneal nerve and proximally. Magnetic resonance (MR) images obtained in these patients demonstrated some unusual findings, including the presence of a cyst within the tibial and sural nerves in the popliteal fossa region, and spontaneous regression of the cysts, which was observed on serial images obtained weeks apart. The authors identified a clinical outlier, a case that could not be understood within the context of their previously reported theory of intraneural ganglion cyst formation. Described 32 years ago, this patient had a tibial neuropathy and was found at surgery to have tibial, peroneal, and sciatic intraneural cysts without a joint connection. The authors' hypothesis about this case, based on their unified theory, was twofold: 1) the lesion was a primary tibial intraneural ganglion with proximal extension followed by sciatic cross-over and distal descent; and 2) a joint connection to the posterior aspect of the superior tibiofibular joint with a remnant cyst within the articular branch would be present, a finding that would help explain the formation of different cysts by a single mechanism. The authors proved their hypothesis by careful inspection of a recently obtained postoperative MR image.

CONCLUSIONS

These three cases together with data obtained from a retrospective review of the authors' clinical material and findings reported in the literature provide firm evidence for mechanisms underlying intraneural ganglia formation. Thus, expansion of the authors' unified articular theory permits understanding and elucidation of unusual presentations of intraneural cysts. Whereas an articular connection and fluid following the path of least resistance was pivotal, the authors now incorporate dynamic aspects of cyst formation due to pressure fluxes. These basic principles explain patterns of ascent, cross-over, and descent down terminal nerve branches based on articular connections, paths of diminished resistance to fluid flow within recognized anatomical compartments, and the effects of fluctuating pressure gradients.

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.

Dynamic phases of peroneal and tibial intraneural ganglia formation: a new dimension added to the unifying articular theory

Object

The pathogenesis of intraneural ganglia has been a controversial issue for longer than a century. Recently the authors identified a stereotypical pattern of occurrence of peroneal and tibial intraneural ganglia, and based on an understanding of their pathogenesis provided a unifying articular explanation. Atypical features, which occasionally are observed, have offered an opportunity to verify further and expand on the authors' proposed theory.

Methods

Three unusual cases are presented to exemplify the dynamic features of peroneal and tibial intraneural ganglia formation.

Results

Two patients with a predominant deep peroneal nerve deficit shared essential anatomical findings common to peroneal intraneural ganglia: namely, 1) joint connections to the anterior portion of the superior tibiofibular joint, and 2) dissection of the cyst along the articular branch of the peroneal nerve and proximally. Magnetic resonance (MR) images obtained in these patients demonstrated some unusual findings, including the presence of a cyst within the tibial and sural nerves in the popliteal fossa region, and spontaneous regression of the cysts, which was observed on serial images obtained weeks apart. The authors identified a clinical outlier, a case that could not be understood within the context of their previously reported theory of intraneural ganglion cyst formation. Described 32 years ago, this patient had a tibial neuropathy and was found at surgery to have tibial, peroneal, and sciatic intraneural cysts without a joint connection. The authors' hypothesis about this case, based on their unified theory, was twofold: 1) the lesion was a primary tibial intraneural ganglion with proximal extension followed by sciatic cross-over and distal descent; and 2) a joint connection to the posterior aspect of the superior tibiofibular joint with a remnant cyst within the articular branch would be present, a finding that would help explain the formation of different cysts by a single mechanism. The authors proved their hypothesis by careful inspection of a recently obtained postoperative MR image.

Conclusions

These three cases together with data obtained from a retrospective review of the authors' clinical material and findings reported in the literature provide firm evidence for mechanisms underlying intraneural ganglia formation. Thus, expansion of the authors' unified articular theory permits understanding and elucidation of unusual presentations of intraneural cysts. Whereas an articular connection and fluid following the path of least resistance was pivotal, the authors now incorporate dynamic aspects of cyst formation due to pressure fluxes. These basic principles explain patterns of ascent, cross-over, and descent down terminal nerve branches based on articular connections, paths of diminished resistance to fluid flow within recognized anatomical compartments, and the effects of fluctuating pressure gradients.

The clinico-anatomic explanation for tibial intraneural ganglion cysts arising from the superior tibiofibular joint

OBJECTIVE

To demonstrate that tibial intraneural ganglia in the popliteal fossa are derived from the posterior portion of the superior tibiofibular joint, in a mechanism similar to that of peroneal intraneural ganglia, which have recently been shown to arise from the anterior portion of the same joint.

DESIGN

Retrospective clinical study and prospective anatomic study.

MATERIALS

The clinical records and MRI findings of three patients with tibial intraneural ganglion cysts were analyzed and compared with those of one patient with a tibial extraneural ganglion cyst and one volunteer. Seven cadaveric limbs were dissected to define the articular anatomy of the posterior aspect of the superior tibiofibular joint.

RESULTS

The condition of the three patients with intraneural ganglia recurred because their joint connections were not identified initially. In two patients there was no cyst recurrence when the joint connection was treated at revision surgery; the third patient did not wish to undergo additional surgery. The one patient with an extraneural ganglion had the joint connection identified at initial assessment and had successful surgery addressing the cyst and the joint connection. Retrospective evaluation of the tibial intraneural ganglion cysts revealed stereotypic features, which allowed their accurate diagnosis and distinction from extraneural cases. The intraneural cysts had tubular (rather than globular) appearances. They derived from the postero-inferior portion of the superior tibiofibular joint and followed the expected course of the articular branch on the posterior surface of the popliteus muscle. The cysts then extended intra-epineurially into the parent tibial nerves, where they contained displaced nerve fascicles. The extraneural cyst extrinsically compressed the tibial nerve but did not directly involve it. All cadaveric specimens demonstrated a small single articular branch, which derived from the tibial nerve to the popliteus. The branch coursed obliquely across the posterior surface of the popliteus muscle before innervating the postero-inferior aspect of the superior tibiofibular joint.

CONCLUSIONS

The clinical, MRI and anatomic features of tibial intraneural ganglion cysts are the posterior counterpart of the peroneal intraneural ganglion cysts arising from the anterior portion of the superior tibiofibular joint. These predictable features can be exploited and have implications for the pathogenesis of these intraneural cysts and treatment outcomes. These ganglion cysts are joint-related and provide further evidence to support the unifying articular theory. In each case the joint connection needs to be identified preoperatively, and the articular branches and the superior tibiofibular joint should be addressed operatively to prevent cyst recurrence.