Holmes Tremors in a 60-year-old Woman Following Primary Brainstem hemorrhage (PBH) Responsive to Standard Dose of Trihexyphenidyl: A case report and literature review

Introduction: The Holmes tremor, once known as rubral or mesencephalic tremor, is an uncommon and atypical condition that presents as an irregular resting tremor, often accompanied by an action tremor that worsens with certain postures. This phenomenon is primarily caused by vascular or traumatic injuries that impact the cerebellothalamocortical pathway and the Guillain-Mollaret triangle. Currently, there is no therapeutic protocol based on randomized clinical trials, and the efficacy of the proposed treatments varies significantly. First-line pharmacological treatments include levodopa, levetiracetam, and trihexyphenidyl, the latter frequently prescribed at high doses. We present a case of Holmes tremor associated with a pontine-mesencephalic hematoma, which showed a favorable response to standard-dose trihexyphenidyl. Clinical case: A 60-year-old patient presented with a hemorrhagic stroke in the brainstem secondary to hypertensive microangiopathy, characterized by a sudden disturbance in consciousness and a favorable outcome. After twenty-six days, Holmes tremors were observed in the right brachiofacial area. The patient was started on trihexyphenidyl at standard doses, which were gradually increased to a total of 12 mg taken in three doses, resulting in nearly complete resolution of the tremors. At the three-month follow-up, the patient exhibited only mild dysarthria as a residual effect. Conclusion: The choice to administer trihexyphenidyl was particularly challenging due to the patient's pre-existing vigilance issues and her advanced age. Nonetheless, by refraining from high doses, the tremors were resolved, underscoring the necessity for comprehensive studies to formulate effective treatment protocols and to personalize therapeutic decisions for each individual patient Keywords: Holmes tremor, primary brainstem hemorrhage (PBH), Trihexyphenidyl, elderly patient, case report.