A Case of Cervicogenic Wrist Clonus Mimicking Action-Induced Tremor.

Cervicogenic wrist clonus is a rare form of action-induced hand tremor, the cases of which are not well understood. Wrist clonus from cervical spondylotic myelopathy (CSM) can be mistaken for tremor-like shaking in some patients. Here, we describe a case of a 67-year-old man who developed wrist tremors that occurred when both arms were flexed and raised. The tremor was clearly triggered by certain postures and did not respond to L-DOPA or β-blockers. The patient had no numbness or muscle weakness. A cervical MRI revealed a snake-eye phenomenon at the C3-5 levels. Computed tomography showed osteophyte formation at the C3-5 levels. Based on these findings, a localized lesion in the C6 spinal segment of the CSM was suspected, and posterior decompression surgery was performed. Tremors improved slightly after the procedure. The patient showed isolated wrist tremors without long-tract signs caused by CSM. This case highlights the importance of considering cervicogenic wrist clonus as a possible cause of tremors to ensure accurate diagnosis and timely surgical treatment.