Extensive spinal intradural arachnoid cyst exhibiting a "double cord sign" on magnetic resonance imaging

Retrospective case study.

To report on a case with an extensive intradural arachnoid cyst that caused left hemiparesis.

Intradural arachnoid cysts are not common causes of spinal cord compression and myelopathy. Although arachnoid cysts of the spine have been occasionally reported, cases with extensive intradural arachnoid cysts associated with hemiparesis are rarely reported.

The patient was a 43-year-old woman who had cervical myelopathy symptoms, including radiating pain and left limb hemiparesis with gait disturbance. Magnetic resonance imaging revealed an extensive intradural extramedullary multi-septated cyst from the C6-T12, exhibiting a double cord sign on the T2-weighted axial image of the spine. The mass blocked normal cerebrospinal fluid flow, which led to cord compression. Two stages of operations were planned because of the patient's health status. The patient underwent laminectomy and cyst wall resection on the level of the T5-T7, which had the most compressed lesion. From C6-T2, a right side unilateral laminectomy was performed to resolve the right limb's neurology after the first operation.

Hypoesthesia and the radiating pain were improved immediately postoperatively; however, motor power at the C8-T1 level of the right unaffected side was impaired and included finger abduction and finger flexion, which decreased to 4/5. During the second operation, the arachnoid cyst was exposed by performing a right unilateral laminectomy. The patient's neurologic symptoms were improved without neurologic sequelae.

In the case of an extensive cyst that exhibits a double cord sign, an intradural arachnoid cyst should be suspected as a differential diagnosis. Without radical excision of all lesions, neurologic symptoms can be recovered by performing selective resection and CSF normalization can be achieved even at extensive levels.