Spinal Extradural Arachnoid Cyst: A Case Report
A 65-year-old male patient with history of fall-down injury from a cliff 50 years ago presented progressive paraparesis from 15 years following trauma. At the time of injury, the patient had transient back pain and returned to his normal daily life as a laborer after recovering from lumbago. After 15 years from the accident, mild motor weakness of bilateral legs developed, which progressed slowly, and the patient had been unable to walk since 35 years from the time of injury. Voiding difficulty and urinary incontinence developed two years ago. On admission, the patient presented motor power of grade two at both lower extremities, and ambulation was impaired. Muscle atrophy of both lower extremities was prominent. Knee jerk and ankle jerk were absent bilaterally. The patient had no significant underlying diseases.\nWhole spine MRI revealed long segmental cystic lesion of CSF signal intensity at dorsal extramedullary space of T11 to L3 level suggesting arachnoid cyst with diffuse cord compression (). The spinal cord was displaced anteriorly and flattened. Associated findings included nerve root sleeve cyst at T2 to T3 level located leftwardly. Electromyelography revealed bilateral lumbosacral polyradiculopathy consistent with cauda equina syndrome of chronic state.\nThe arachnoid cyst was exposed by total laminectomy of T12 and extended laminotomy to L1 level. Large sized epidural arachnoid cyst was located dorsal to the dural tube. On exposure, 7×5 mm sized ovoid shaped dural defect was identified at right sided dorsolateral aspect of the dura mater between nerve root sleeves at T11 and T12 level (). The cyst contained clear fluid suggestive of CSF. Microsurgical repair of the dural defect was performed using two sutures and application of collagen fleece (Tachocomb®) and fibrin glue (Tissucol®). Following repair of the dural defect, no further leakage of CSF was verified on Valsalva maneuver in head-up position.\nHistologic examination of the cyst wall revealed pathological diagnosis as arachnoid cyst. Postoperative MRI evaluation performed at 1 month following the surgery revealed decreased size of arachnoid cyst at T11 to L3 level along with decompression of the flattened spinal cord (). The neurological status including motor power of both lower extremities was stationary on follow-up examination at 5 months postoperatively. The patient is currently on supportive rehabilitation therapy.