Cerebellum theta-burst stimulation as a supplementary treatment for tremor induced by bilateral hypertrophic olivary degeneration: a case report

Hemorrhage can result in bilateral hypertrophic olivary degeneration (HOD) by damaging the dentato-rubral-olivary pathway, which may lead to tremor that is resistant to pharmacological management. In recent years, the cerebellum has emerged as a promising target for noninvasive brain stimulation in the treatment of post-stroke motor dysfunction. However, the effects of noninvasive brain stimulation on post-stroke tremor remain uncertain. To describe and evaluate the effects of theta-burst stimulation (TBS) on tremor induced by bilateral HOD. A 50-year-old man with pontine hemorrhage was admitted to hospital because of unilateral tremor, dizziness, and ataxia. The intention tremor on the right side at a frequency of 2–3 Hz was pronounced. The Fahn-Tolosa-Marin tremor rating scale and Scale for Assessment and Rating of Ataxia were 61 and 25 points. Magnetic resonance imaging (MRI) performed 8 months after symptom onset revealed bilaterally enlarged inferior olivary nuclei. The patient underwent physical therapy for 4 months and pharmacological treatment for 2 months, but his right-sided tremor persisted. Consequently, in addition to personalized physiotherapy and medications, continuous TBS (cTBS) was applied to the right cerebellum, using 60% of the right hemisphere resting motor threshold (RMT) as the stimulation intensity. After a two-week intervention, cTBS protocol led to worsened dizziness without any alleviation of the tremor. Cerebellum-targeted TBS did not improve tremor induced by HOD. These findings highlight the need for a deeper understanding of the underlying pathophysiology of HOD-related tremor, which facilitates the development of more effective and targeted strategies in the future.