Intradural spinal arachnoid cyst resection: implications of duraplasty in a large case series.

OBJECTIVE Optimal diagnosis and management strategies for intradural spinal arachnoid cysts (SACs) are still unresolved given the rare nature of this entity, with few large case series and virtually no statistical analyses of patient characteristics in the literature. Here, the authors studied a large patient cohort with these lesions to determine whether pre- or postoperative attributes could be used to aid in either diagnosis or prognosis. METHODS A chart review was completed at a single institution for the period from 2002 to 2016 to determine the preoperative characteristics and postoperative outcomes of 21 patients with exclusively intradural SACs. Patients were assessed for symptoms such as weakness, pain, sensory changes, bowel and/or bladder dysfunction, and gait changes. Postoperatively, patients were analyzed for symptom improvement, complication occurrence, and duration of follow-up. RESULTS Approximately two-thirds of the patients in this series had developed SACs idiopathically, and the mean duration of symptoms prior to diagnosis was 15 months among all patients. A slight majority (57%) underwent CT myelography in the course of diagnosis, and a quarter of the patients had a syrinx. There was a statistically significant association between location of the SAC and number of presenting signs and symptoms; that is, patients with cysts in the lumbosacral region had more symptoms than those with cysts at the cervical or thoracic levels (p = 0.031). Overall, outcomes were largely positive, with approximately 60%-70% of patients experiencing postoperative improvement in symptoms, with motor weakness showing the highest response rate (71%) and pain symptoms the least likely to subside (50%). In the cohort with preoperative pain, those who had undergone expansile duraplasty were significantly more likely to experience relief of their pain symptoms (p = 0.028), which may have been a result of the superior restoration of cerebrospinal fluid pathways allowing for more adequate reduction in compression. CONCLUSIONS In this large case series on intradural SACs, new light has been shed on aspects of both pre- and postoperative care for patients with these rare lesions. Specifically, the authors revealed that lumbosacral intradural SACs may be associated with a higher disease burden and that patients who undergo expansile duraplasty may have an increased likelihood of experiencing postoperative pain relief.