Twice the Leak: Managing CSF Fistulas in a Recurrent Thoracic Arachnoid Cyst-A Case Report.

Background and Clinical Significance: Spinal arachnoid cysts are rare lesions that may become symptomatic through progressive spinal cord compression. We present a complex case of a thoracic extradural SAC in a 17-year-old male, managed through a stepwise, multidisciplinary approach. Case Presentation: The patient presented with progressive lower limb weakness, right knee paresthesia, and urinary hesitancy following physical exertion. MRI revealed a large posterior extradural SAC extending from T2-T3 to T8, with associated spinal cord compression. Initial management involved T8 laminectomy and cyst fenestration under intraoperative neurophysiological monitoring, with partial clinical improvement. However, early recurrence with pseudomeningocele formation prompted a second surgery, including external CSF drainage. Persistent cerebrospinal fluid (CSF) leakage led to targeted epidural blood patching, followed by temporary stabilization. Due to continued cyst enlargement and spinal cord compression, definitive surgical repair was undertaken: fistula clipping at T3 and embolization with platinum coils inside the cystic cavity, combined with a new blood patch. This novel technique resulted in radiological improvement and clinical stabilization. Conclusions: This case highlights the diagnostic and therapeutic challenges of managing symptomatic extradural SACs, particularly in young patients. Our experience underscores the utility of a staged approach involving surgical decompression, neuroimaging-guided interventions, and definitive dural repair. The combination of fistula clipping and coil embolization may offer a promising strategy for refractory cases, potentially reducing recurrence and preserving neurological function.