Teaching NeuroImages: Recurrence of a sural intraneural ganglion cyst after sural nerve resection

Intra-neural ganglion cyst of the lateral dorsal cutaneous nerve: an uncommon cause of lateral ankle pain

INTRODUCTION

An intra-neural ganglion cyst of the lateral dorsal cutaneous branch of the sural nerve is rare, with only a few cases reported in the literature.

MATERIALS AND METHODS

We carried out a retrospective investigation of patients with an intraneural ganglion cyst of the lateral dorsal cutaneous nerve.

RESULTS

We present a case series of four patients with intra-neural ganglion cysts of the lateral dorsal cutaneous nerve, the distal continuation of the sural nerve at the lateral aspect of the foot.

CONCLUSION

Intra-neural ganglion cysts of the lateral dorsal cutaneous nerve are rare. They represent a relatively uncommon source of lateral ankle pain, which can easily be diagnosed with ultrasound (US) and magnetic resonance imaging and managed effectively with US-guided aspiration or surgical excision.

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.

Concurrent Lateral Dorsal Cutaneous and Deep Peroneal Intraneural Ganglion Cysts in the Foot

Intraneural ganglion cysts are non-neoplastic collections of mucinous material within the epineurium of peripheral nerves. We present a rare case of 2 intraneural ganglion cysts in separate nerves of the foot, originating from different joints within the same joint complex. Our findings add to the large body of evidence supporting the unifying articular (synovial) theory. We emphasize the importance of delineating the cyst morphology and origins using high-resolution magnetic resonance imaging before surgery and searching for and resecting the articular branch or branches during surgery.