Background: Chronic subdural hematoma (CSDH) is often found in the elderly owing to slight head trauma and is associated with several neurological disorders. Neurological deficits are cured by a simple surgical removal of the hematoma; however, these deficits persist if there is insufficient hematoma removal. It is rare for patients to continue having neurological disorders once the hematoma is removed.

Case report: A 61-year-old woman presented with gait disturbance. She was diagnosed with a subdural hematoma through head computed tomography. After hematoma irrigation, her gait disturbance exacerbated, and she developed urinary tract dysfunction. Ubiquitous neurodegeneration in the midbrain and spinal cord was suspected owing to a hyperintense signal on fluid-attenuated inversion recovery of magnetic resonance imaging. The anti-aquaporin 4 antibody was detected in the patient’s serum, and she was diagnosed with neuromyelitis optica (NMO).

Conclusions: Progressive NMO caused gait dysfunction and triggered head trauma, followed by CSDH. Although NMO rarely causes CSDH, it should be considered in uncommon cases of CSDH.