Severe Normal Pressure Hydrocephalus Symptom Caused by Rheumatoid Arthritis-induced Atlantoaxial Subluxation: A Case Report.

Introduction: Normal pressure hydrocephalus (NPH) has three characteristics: Gait disorder, urinary incontinence, and amnesia. We report a case of atlantoaxial subluxation-related NPH in a patient whose symptoms were dramatically improved by atlantoaxial fusion surgery. Case Report: A 67-year-old woman presented complaining of walking disturbance. 4 weeks after her first presentation and initial diagnosis of atlantoaxial subluxation associated with rheumatoid arthritis, the patient fell and fractured her right patella. After open surgery for the fracture with spinal anesthesia, she had urinary incontinence, cognitive decline, and gait disturbance, and brain computed tomography showed enlarged ventricles. Atlantoaxial fusion surgery was performed 8 weeks after the first presentation. Postsurgically, improvement of her memory and urinary function was noted and she was able to walk with the assistance of a cane and perform activities of daily living independently. Even 6 years after the surgery, the enlargement of the ventricles ameliorated, there was no abnormality in cognition, and she was able to walk alone and run a business. Conclusion: The atlas was subluxated, even when the cervical spine was in a neutral position, and the spinal cord was seriously compressed, which impeded cerebrospinal fluid flow. We speculate changes in cerebrospinal pressure due to spinal anesthesia-induced NPH-like symptoms, which were improved by indirect spinal decompression by atlantoaxial reduction with atlantoaxial fusion.