gms | German Medical Science

Objective: Intraneural ganglion cysts are rare, benign and nonneoplastic lesions that spread within the epineurium. Mostly, the peroneal nerve is affected causing weakness of the anterior tibial muscle (ATM) by compression of the peroneal deep branch. We report on a large series of patients undergoing surgical treatment at our department on clinical outcome and investigated recurrence rate in correlation to knee pathology.

Methods: Clinical outcome of 29 patients treated with symptomatic intraneural ganglion cysts at our between Nov. 2002 and July 2016 were analyzed retrospectively. Standard surgical therapy was ligating and severing the articular branch and decompressing the cyst. We evaluated sunction of the peroneal nerve in all patients prae- and postoperatively using Janda motor function grading system. Additionally, sensory deficits and pain within innervation zone were analyzed. Mean follow up were 57 months (Range 3-156 months). Recurrent cysts and knee pathology were determined based on MRI-follow up images or ultrasound examination. Furthermore surgical complications and role of an external muscle stimulation after surgery were evaluated.

Results: Mean-time of weakness before surgery were 11 weeks. Muscle strength just before surgery was in mean M 1.5 for ATM, M 1 for extensor halluces longus muscle (EHL) and M 3 for peroneal muscle (PM). After surgery, weaknes improved to the mean of M 4 for ATM, M 3.5 for EHL and M 5 for PM. Only in two cases no improvement of ATM has been achived. Two patients treated at our department developed symptomatic recurrent cysts and needed additional surgery. Asymptomatic recurrent cysts were detected in three patients, whereas extraneural ganglion cysts were found in three patients. One patient developed new high-grade pareses of ATM, EHL and PM after surgery and needed additional surgery, which resulted in complete muscle functional restoration. We could not found significant correlation between the functional improvement and using of an external muscle stimulation after surgery. Knee pathology had furthermore no influence on breeding recurrent cysts.

Conclusion: Clinical outcome after ligation and sectioning of the joint and decompression of intraneural ganglion cyst is excellent even after weeks of weaknes before surgery. The recurrent rate is very low after ligation of the articular branch independent of knee pathology, whereas surgery had no influence on formation of extraneural ganglion cysts in accordance to progressive osteoarthritis.