Multiple extradural spinal arachnoid cysts causing diffuse myelomalacia of the spinal cord

Extradural spinal cyst is a rare cause of compression myelopathy. It is usually solitary and its typical location is posterior to the spinal cord. We present a case of multiple spinal arachnoid cysts causing diffuse myelomalacia secondary to a significant compression of the spinal cord with no symptom relief after surgical decompression.

A 35-year-old female patient presented to our hospital complaining of progressive weakness and numbness of both lower extremities for the last 2 months, being more prominent on the right side. Her history was significant for back pain that started after a vaginal delivery 1 year ago. Spinal MRI revealed multiple extradural arachnoid cysts and diffuse myelomalacia. A T4-T6 level laminectomy was performed. The cyst was nearly totally resected. There was partial symptomatic relief after surgery, but 5 months later her symptoms worsened. MRI revealed nodular syringomyelia and atrophy of the thoracic spinal cord.

Extradural spinal arachnoid cyst is to be considered in the differential diagnosis of spinal cord compression. Vaginal delivery may accelerate the process and symptoms by a sudden increase in the cyst size. In cases of myelomalacia secondary to cyst pressure postoperative results are quite poor.