Positional head tremor in professional billiards player

Excerpt

A 34-year-old right-handed man was referred to our movement disorders clinic due to a head tremor. He was a professional billiards player, playing billiards for twenty-two years, 7 h per day. He had noticed involuntary neck movements for two years, which occurred exclusively while playing billiards and in the position of striking a ball (video 1). The patient didn’t report these movements during other activities or sports. He didn’t report any family history of neurologic or other chronic disorders. On neurological examination, there was no Kayser-Fleischer ring. Eye movements were normal and cerebellar tests were unremarkable, He did not have any sensory or motor abnormalities. No other movement disorders were found in the neurological examination. When he held his head in the position of striking a ball, bending his trunk at the hips at approximately 80–90° while supporting his head against gravity by keeping his neck straight, a jerky, high-frequency, and low-amplitude tremor appeared, and whenever he tried to hold it in a downward and upward position, the tremor disappeared (Video2). The tremor was not distractible. There were no limitations in neck movements, including flexion, extension, and head rotation. No abnormal neck posturing or tremor was observed in the standing position. …