Spinal arachnoid cyst as a cause of isolated, progressive, bilateral C5–C6 radiculopathy

Abstract

A 41-year-old man presented with bilateral shoulder weakness and pain. The symptoms had been present for 5 years on the left side and for 3 years on the right. His medical history was remarkable for cervical trauma related to a fall 8 years earlier. Neurologic examination showed severe bilateral weakness of shoulder abduction, with atrophy of the deltoid, supraspinatus, and infraspinatus muscles (Fig. 1). Biceps tendon reflexes were decreased bilaterally. Electromyography findings were consistent with bilateral C5–C6 radiculopathy. Magnetic resonance imaging revealed a spinal intradural arachnoid cyst extending from the level of C2 to L3 (Fig. 2), displacing the spinal cord posteriorly. Computed tomography-myelography showed early filling of this cyst with contrast material, suggesting a large communication with the subarachnoid space. The patient underwent an L2–L3 laminotomy with cyst fenestration and shunting. Three months after surgery, a slight improvement of strength was noticed. Radiculopathy or myelopathy resulting from compression by a spinal cyst is rare. Nabors et al. classified spinal cysts as extradural without spinal nerve root involvement (Type I), extradural with spinal nerve root involvement (Type II), and intradural (Type III) [1]. Arachnoid cysts, the most common spinal intradural cysts, are either congenital or acquired. The majority of acquired arachnoid cysts develop after spinal cord trauma, subarachnoid hemorrhage, or infection [2]. These lesions are usually posterior to the spinal cord in the thoracic region. Subarachnoid cysts anterior to the spinal cord, which are less common, generally have greater craniocaudal extension and are often associated with previous trauma [2]. The extensive subarachnoid cyst in this case is very likely related to the reported previous trauma. It is possible that the findings were the result of stretch or compression injuries to the nerve roots.