Recognition of peroneal intraneural ganglia in an historical cohort with "negative" MRIs

Complete foot drop due to atypical peroneal ganglion in a 13 ½ year old boy

INTRODUCTION

Peroneal nerve palsy due to compression by an intraneural ganglion is an uncommon entity in the pediatric setting with a need for surgical treatment. Uniquely in this case, the ganglion presented as an elongated instead of a typical round cyst, delaying diagnosis and treatment.

CASE PRESENTATION

We present the case of a 13 ½ year old boy with increasing peroneal nerve palsy due to an atypically shaped intraneural ganglion. An MRI of the knee revealed an elongated peroneal ganglion compressing the nerve between the lateral insertion of the gastrocnemius muscle and fibular head over a length of 10 cm. After surgical decompression and physiotherapy the peroneal nerve recovered well, achieving M 4-5 one year after surgery.

CONCLUSION

The atypical shape of the present peroneal ganglion delayed diagnosis and correct treatment. Though rare in the pediatric setting, this entity must be specifically looked for during the diagnostic workup of peroneal palsy, for time to surgery determines neurological outcome.

The value of high-resolution imaging in an occult peroneal intraneural ganglion cyst: illustrative case

BACKGROUND

Foot drop is a common complaint with a broad differential diagnosis making imaging a key part of the diagnostic workup. The authors present a patient with an occult peroneal intraneural ganglion cyst who underwent imaging with high-frequency ultrasound (US) and high-resolution magnetic resonance imaging (MRI) to highlight the role of such techniques in cases of peroneal neuropathy.

OBSERVATIONS

Intraneural ganglion cysts are emerging as a common cause of common peroneal neuropathy. Imaging with US and MRI is a valuable tool used to illustrate the pertinent anatomy and identify the articular branch joint connection and cyst as part of the surgical planning and definitive management.

LESSONS

Intraneural ganglion cysts can be small or nearly invisible and failure to appreciate the intraneural cyst can lead to symptom or cyst persistence or recurrence. High-resolution modalities can be useful in the diagnosis and surgical planning of difficult cases.

Does complete regression of intraneural ganglion cysts occur without surgery?

PURPOSE

The dynamic nature of intraneural ganglion cysts, including spontaneous expansion and regression, has been described. However, whether these cysts can regress completely in the absence of surgical management has important therapeutic implications. Therefore, we aim to review the literature for cyst regression without surgical intervention.

METHODS

We reviewed our database of 970 intraneural ganglion cysts in the literature to search for evidence of complete regression based on strict radiologic confirmation, either spontaneously, or after percutaneous cyst aspiration or steroid injection.

RESULTS

We did not find any examples of complete regression without surgical treatment that met inclusion criteria. Spontaneous regression was reported in four cases; however, only two cases had follow-up imaging, both of which demonstrated residual cysts. Nineteen cases of percutaneous intervention were found in the literature, 13 of which reported clinical improvement following aspiration/steroid injection; however, only seven cases had available imaging. Only two cases reported complete resolution of cyst on MR imaging at follow-up, but reinterpretation found residual intraneural cyst in both cases.

CONCLUSION

We believe that pathology (structural abnormalities and/or increased joint fluid) always exists at the joint origin of intraneural ganglion cysts which persist even with regression of the cyst. The persistence of a capsular abnormality or defect can lead to recurrence of the cyst in the future, and while imaging may show dramatic decreases in cyst size, truly focused assessment of images will show a tiny focus of persistent intraneural cyst at the joint origin. Thus, expectant management or percutaneous intervention may lead to regression, but not complete resolution, of intraneural ganglion cysts.

Joint Outcomes Following Surgery for Superior Tibiofibular Joint-Associated Peroneal Intraneural Ganglion Cysts

BACKGROUND

Intraneural ganglion cysts are joint-connected, with the primary pathology residing in the associated joint. For peroneal intraneural ganglion cysts, the surgical strategy can include resection of the synovial surface of the superior tibiofibular joint (STFJ). However, the rate of instability postoperatively is unclear.

OBJECTIVE

To evaluate the rate of STFJ instability, following surgery for peroneal intraneural ganglion cysts. The second goal of the study was to assess the relationship between volume of resection of the STFJ and risk of extraneural recurrence.

METHODS

We performed a retrospective analysis of a cohort of patients with peroneal intraneural ganglion cysts. We analyzed clinical factors, including recurrence, and assessed the rate of postoperative STFJ instability. We created 3-dimensional models of the STFJ pre- and postoperatively to compare the volume of resection in recurrent cases and nonrecurrent cases using a case-control design.

RESULTS

The total cohort consisted of 65 subjects. No patient had evidence of radiological or clinical instability of the STFJ postoperatively. Extraneural radiological recurrence occurred in 6 (9%) patients. No intraneural recurrences were observed. The average volume of resection for patients with recurrence was 1349 mm3 (SD = 1027 mm3) vs 3018 mm3 (SD = 1433 mm3) in controls that did not have a recurrence (P = .018).

CONCLUSION

This study supports performing an aggressive STFJ resection to minimize the risk of extraneural recurrence. Superior tibiofibular joint resection is not associated with postoperative joint instability. A smaller volume resection is correlated with recurrence risk.

Imaging of Damaged Nerves

Nerve imaging is an important component in the assessment of patients presenting with suspected peripheral nerve pathology. Although magnetic resonance neurography and ultrasound are the most commonly utilized techniques, several promising new modalities are on the horizon. Nerve imaging is useful in localizing the nerve injury, determining the severity, providing prognostic information, helping establish the diagnosis, and helping guide surgical decision making. The focus of this article is imaging of damaged nerves, focusing on nerve injuries and entrapment neuropathies.

Long-Term Functional Outcome After Surgical Treatment of Peroneal Intraneural Ganglion Cyst

BACKGROUND

Intraneural ganglia are benign mucinous cystic formations that originate within the epineurium of peripheral nerves. Different treatments have been recommended, with an overall satisfactory outcome. In this paper, we aim to evaluate the long-term outcomes of surgical treatment of peroneal intraneural ganglia by reviewing our local institutional experience.

METHODS

We performed a case series review of peroneal intraneural ganglia surgical treatment performed by the senior author. Demographic and surgical details were abstracted from the medical record for each patient. Electrodiagnostic studies and magnetic resonance imaging (MRI) were performed in all patients pre- and postoperatively.

RESULTS

Eight men were enrolled, with an average age at time of surgery of 47.5 years (range 28-68 years). Motor testing revealed a preoperative deficit of dorsiflexion, eversion, and toe extension in 7 patients, with a median preoperative Medical Research Council (MRC) score of 0/5. Sensory loss in the distribution of the common peroneal nerve was present in 7 patients. Mean clinical follow-up time was 113 months (range 32-189 months). Significant pain relief was achieved in all patients. Overall neurologic function was improved, more so for motor function. The median postoperative dorsiflexion, eversion, and toe extension at last follow-up were MRC score of 5/5. No complications occurred postoperatively. There was no clinical evidence of intraneural recurrence, as confirmed in postoperative MRI. In 2 patients, an extraneural cystic formation was visible in the anterior muscular compartment.

CONCLUSIONS

The data from our series support excellent long-term postoperative motor outcomes with a low recurrence rate. To avoid extraneural recurrence, resection of the superior tibiofibular joint is necessary.

Cystic Adventitial Disease of the Tibial Vein Arising From the Subtalar Joint: A Case Report

Soft tissue ganglion cysts are a well-known cause of tibial nerve compression in the tarsal tunnel. We describe a patient who presented with tibial nerve symptoms and was found to have an adventitial cyst of the tibial vein arising from the subtalar joint, with the joint connection confirmed both on imaging and at surgery. Surgical decompression of the cyst with transection of the vascular pedicle arising from the subtalar joint improved her symptoms at 6 months, and postoperative magnetic resonance imaging showed resolution of the cyst. Cystic adventitial disease is a rare, poorly understood condition in which a cyst is identified in the adventitia of a vessel, usually an artery. Only 3 cases of adventitial cysts have been reported in the foot and ankle region, 2 in the lesser and 1 in the greater saphenous vein. None of the previous cases have been recognized to be joint connected. This case provides additional evidence for an articular origin for adventitial cysts and helps guide management strategies for these joint-connected cysts.

Indications for neuromuscular ultrasound: Expert opinion and review of the literature

Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.

Intraoperative intravenous fluorescein as an adjunct during surgery for peroneal intraneural ganglion cysts

The intraoperative use of intravenous fluorescein is presented in a case of peroneal intraneural ganglion cyst. When illuminated with the operative microscope and yellow filter, this fluorophore provided excellent visualization of the abnormal cystic peroneal nerve and its articular branch connection. The articular (synovial) theory for the pathogenesis of intraneural cysts is further supported by this pattern of fluorescence. Further, our report presents a novel use of fluorescein in peripheral nerve surgery.

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.