Abstract

The spinal extradural arachnoid cyst is the rare and uncommon cause of spinal cord compression leading to neurological deficit. The aetiology of this extradural cyst is still unclear. They are considered to arise from congenital defects in the dura. Through this dural defect they communicate with subarachnoid space, hence contain the CSF (cerebro-spinal fluid). Most reports describe such cysts communicating with the intrathecal subarachnoid space through a small defect in the dura. Our case is unique because we found obliterated fibrous cyst tract adherent to the junction of nerve root sleeve and the thecal sac, representing probable pre-existing communication of cyst to subarachnoid space which got obliterated over the period of time. Such fibrous communication was considered in literature, but was never been demonstrated. Only one case of non-communicating extradural arachnoid cyst is previously reported in literature, but fibrous tract was not seen. Surgery remains the mainstay of treatment modality in symptomatic cases. Surgical excision of the cyst with closure of dural defect is recommended treatment. MRI (magnetic resonance imaging) is diagnostic investigation of choice. Hereby we report a case of posttraumatic, non-communicating, lower thoracic region, spinal extradural arachnoid cyst in a young male who presented with lower back pain with paraparesis. Delayed-onset post traumatic extradural arachnoid cyst should be taken into consideration in the differential diagnosis of intraspinal cysts. We discuss clinical features, mechanism, investigations, surgical management and relevant literature.

Keywords: Extradural; Non-communicating; Spinal arachnoid cyst