41. Long term outcomes following surgical treatment of spinal arachnoid cysts

BACKGROUND CONTEXT Spinal arachnoid cysts (SACs) are rare, cerebrospinal fluid-filled sacs lined by an arachnoid membrane in the spinal canal. When resistant to conservative management, surgical treatment is typically recommended for those with debilitating symptoms. However, evidence for long-term symptom resolution in these patients is lacking. PURPOSE To determine long-term symptom resolution in patients surgically treated for SACs. STUDY DESIGN/SETTING Population-based retrospective cohort study. PATIENT SAMPLE Patient surgically treated for SACs at the primary referral center in Stockholm. METHODS Single-center population-based cohort-study of all patients surgically treated for SACs between 2005-2020. Baseline and short-term data were collected using the patients’ electronic charts whereas structured telephone interviews were used for the appraisal of long-term symptom resolution. RESULTS Thirty-four patients, with a median postoperative follow-up time of 8.0 years, were included. Cyst excision was performed in 11 (32%) cases, and fenestration in the remaining 23 (68%). At long-term follow-up, surgical treatment had resulted in a significant improvement in both American Spinal Injury Association Impairment Scale (AIS) (p = 0.012) and modified Japanese Orthopedic Association score (p = 0.005). Sensory deficit was the symptom that most often improved (81%), followed by pain (74%) and motor function (64%). On the other hand, bowel and bladder (50%), and gait dysfunction (33%) were less likely to improve. Deterioration in AIS was observed in two patients, of which one could be attributed to a surgical complication. Cyst recurrence requiring new surgery was seen in 5 (15%) cases. CONCLUSIONS This study presents a consecutive population-based series of patients surgically treated for symptomatic intra- or extradural SACs, with the longest follow-up time to date (average 8.0 years). Postoperative complications were rare and generally of low clinical significance. Surgical treatment was associated with significant long-term improvement in sensory deficits, pain, and motor function, unlike gait and bowel and bladder dysfunction which remained largely unchanged throughout the follow-up period. We hence conclude that microsurgical cyst fenestration or excision is a safe treatment option for these patients, and that the neurological improvements seen in the immediate postoperative phase are likely to translate into sustained long-term results. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs. Spinal arachnoid cysts (SACs) are rare, cerebrospinal fluid-filled sacs lined by an arachnoid membrane in the spinal canal. When resistant to conservative management, surgical treatment is typically recommended for those with debilitating symptoms. However, evidence for long-term symptom resolution in these patients is lacking. To determine long-term symptom resolution in patients surgically treated for SACs. Population-based retrospective cohort study. Patient surgically treated for SACs at the primary referral center in Stockholm. Single-center population-based cohort-study of all patients surgically treated for SACs between 2005-2020. Baseline and short-term data were collected using the patients’ electronic charts whereas structured telephone interviews were used for the appraisal of long-term symptom resolution. Thirty-four patients, with a median postoperative follow-up time of 8.0 years, were included. Cyst excision was performed in 11 (32%) cases, and fenestration in the remaining 23 (68%). At long-term follow-up, surgical treatment had resulted in a significant improvement in both American Spinal Injury Association Impairment Scale (AIS) (p = 0.012) and modified Japanese Orthopedic Association score (p = 0.005). Sensory deficit was the symptom that most often improved (81%), followed by pain (74%) and motor function (64%). On the other hand, bowel and bladder (50%), and gait dysfunction (33%) were less likely to improve. Deterioration in AIS was observed in two patients, of which one could be attributed to a surgical complication. Cyst recurrence requiring new surgery was seen in 5 (15%) cases. This study presents a consecutive population-based series of patients surgically treated for symptomatic intra- or extradural SACs, with the longest follow-up time to date (average 8.0 years). Postoperative complications were rare and generally of low clinical significance. Surgical treatment was associated with significant long-term improvement in sensory deficits, pain, and motor function, unlike gait and bowel and bladder dysfunction which remained largely unchanged throughout the follow-up period. We hence conclude that microsurgical cyst fenestration or excision is a safe treatment option for these patients, and that the neurological improvements seen in the immediate postoperative phase are likely to translate into sustained long-term results.