gms | German Medical Science

Objective: Intraneural ganglion cysts of the peroneal nerve are rare benign, non-neoplastic lesions that spread within the epineurium and predominantly affect the deep branch resulting in weakness of the anterior tibial muscle. Therefore ultrasonography is a helpful tool to detect extent of cyst and to evaluate morphology of the nerve. We have investigated morphology of the peroneal nerve after surgical treatment of intraneural cysts and its correlation with long-term outcome.

Methods: The standard surgical therapy was ligating and severing the articular branch and decompressing the cyst. 15 of collectively 34 treated patients were investigated prospectively clinical and by ultrasonography of the peroneal nerve using 15-7MHz sonic probe in MEAN 53 months after surgery (Range between 4 and 156 months). Results of morphological findings were correlated to clinical outcome. We distinguished between pseudoneuroma-like and neuromatous lesions as well as cyst recurrence. Clinical parameter were documented using the manual muscle testing grading system.

Results: Only 1 patient of re-examined collective developed recurrence cyst. Anterior tibial muscle palsy existed in MEAN 8 weeks before surgery and improved in almost all patients to M5. One patient did not recover, in which we could detect a neuromatous lesion of the motor branch in ultrasonography. We have identified a pseudoneuroma-like lesion in 13 patients. that affected lateral bundles without compression of other fascicles and with extension above the original cyst. Persistent articular branch was not found at all. Cyst recurrence could have been detected in 1 patient without compression of fascicular structures.

Conclusion: Neurosonography is a safe and fast method to evaluate postoperative result after decompression of an intraneural ganglion cyst. Furthermore, morphology of the nerve or cyst recurrence can be identified easily. Pseudoneurom-like lesions of one lateral bundle, which are detected at 13 of 15 patients after surgical treatment of intraneural ganglion cysts correlate with complete muscle function restoration to M5. It could be an evidence of either pressure relief after decompression of an intranueral cyst or a sign of adherence of the collapsed cyst itself.