Ventral Intrameningeal Cyst Treatment and Management: Technical Note

Intrameningeal cysts are rare lesions without definitive etiologies that can involve the dura or arachnoid mater. Spinal arachnoid cysts have been described, and several different etiologies have been hypothesized. This includes one-way valve mechanisms, traumatic herniation of arachnoid through the dura, and abnormal arachnoid membrane proliferation. To the authors' knowledge, no such descriptions exist regarding purely dural-based cystic lesions; however, the authors hypothesize similar mechanisms may be involved. Most notably, a traumatic injury to the dura leading to a one-way valve mechanism may allow for egress of cerebrospinal fluid between the dural layers, splitting them open. This progressive enlargement can lead to displacement of neural elements and subsequent neurological compromise. We describe a 17-year-old girl who presented with progressive neck and back pain, left upper-extremity numbness, bilateral lower-extremity weakness, paresthesias, and numbness without obvious etiology despite an extensive neurologic investigation. She had undergone conservative management options including multiple medications, physical and chiropractic therapy, and epidural steroid injections. Computed tomography myelography revealed a cerebrospinal fluid leak into the lumbar epidural space for which surgical exploration was performed. Despite utilizing fluoroscopy and intrathecal fluorescein, no leak source was identified. Fluid collection was found contained within the dural layers rather than the epidural space. An intracystic blood patch was performed with near-complete resolution of the lesion by 6-week follow-up and near-complete return of neurologic function. Ventral panspinal cysts are an exceedingly rare cause of radiculopathy and myelopathy that can be resolved by an intracystic blood patch.