gms | German Medical Science

Objective: Idiopathic, i.e. not trauma- or tumor-related, intramedullary cysts are rarely found in adult patients. The most frequent location is the conus medullaris region. The current case series – one of the largest of its kind – focuses on surgical planning and technique as well as clinical and radiomorphological outcome.

Method: Retrospective analysis using in-house databases. Outcome results were supplemented by data from a telephone interview. Pre- and postoperative MRI scans that included (3D) constructive interference in steady state (CISS) sequences were performed to exclude a spinal tumor, for surgical planning, and for determination of cyst size. All scans were reevaluated by an experienced neuroradiologist (J.L.). Multimodal intraoperative monitoring (MEP, SSEP, EMG) was routinely performed.

Results: In 8 adult patients (age 55 ± 14 years, exclusively women) microsurgical cyst decompression was performed in the conus medullaris region (n = 7) and the cervical spinal cord (n = 1). The cyst size (MRI) in the sagittal diameter was 3.3 ± 1.4 cm on average. Indications for surgery were myelopathic symptoms or intractable pain (n = 7) and progression in cyst size (n = 1). All patients received preoperative 3D-CISS MRI to detect the site of the thinnest parenchyma overlying the cyst. The surgical approaches were hemilaminectomy in n=4 patients, laminoplasty in n=2 patients, and laminectomy in n=2 patients. Intraoperative monitoring showed an improvement of the MEPs in 50% of the patients, inconspicuous and stable MEPs and SSEPs were found in the remaining patients. Except for one postoperative CSF leak, which necessitated revision surgery, there was no surgical complication and no postoperative deterioration of clinical symptoms. In all symptomatic patients there was a durable clinical improvement (median follow-up 25 months) and pain as well as motor deficits were the symptoms which responded best to the operation (100% complete response each). Postoperative MRI scans showed a reduction of the cyst size by ~ 60%.

Conclusions: Microsurgical decompression of rare idiopathic intramedullary cysts in adult patients represents a safe and promising treatment strategy if 3D-CISS MRI is used for surgical planning and if multimodal intraoperative monitoring is applied.