Successful management of interdural spinal cysts presenting as radiculopathy caused by epidural venous enlargement: illustrative case.

Background: The authors report the first case of thoracic interdural spinal cysts presenting as radiculopathy attributed to overdrainage-related cervical venous plexus enlargement. This case emphasizes the importance of considering interdural spinal cysts and cerebrospinal fluid overdrainage in the differential diagnosis of radiculopathy.

Observations: A 37-year-old male patient with a history of orthostatic headache presented with bilateral deltoid muscle atrophy consistent with C5 radiculopathy. Postcontrast magnetic resonance imaging (MRI) revealed cervical epidural venous plexus enlargement and nerve root compression. Thoracic MRI showed an interdural cyst extending from C7 to T11. In addition, a small defect in the inner layer of the dura, which connects the subarachnoid space to the cyst at the T10 level, was detected on thin-slice MRI. Surgery was performed to close the dural defect, with endoscopic assistance facilitating definitive treatment. Postoperative MRI confirmed the resolution of the spinal cyst and epidural venous enlargement. Furthermore, the patient's symptoms improved.

Lessons: Evaluating the cervical spinal pathology is the common approach for cervical radiculopathy. However, in the authors' case, the presence of thoracic lesions could have been an underlying cause. Hence, identifying this unique clinical presentation can raise awareness among neurosurgeons and lead to better patient outcomes by addressing the underlying pathology in a timely manner. https://thejns.org/doi/10.3171/CASE24533.