Pearls & Oy-sters: A Case Report of Holmes Tremor Due to Nigrostriatal Dopamine Disruption That Responded to Dopamine Replacement Therapy

Abstract

Holmes tremor (HT), also known as midbrain, rubral, or cerebellar pathway outflow tremor, occurs because of disturbances of the cerebellothalamic pathway. This tremor is usually related to lesions in the midbrain peduncular region involving the superior cerebellar peduncle, the red nucleus, and possibly the nigrostriatal circuitry. Common etiologies resulting in HT include tumor, ischemia, and demyelination. We report a case of progressive left-sided HT in an otherwise healthy man with additional symptoms of parkinsonism, hypoesthesia, right oculomotor nerve palsy, cognitive dysfunction, and hypersomnolence. Imaging investigations revealed a right-sided thalamic and midbrain glioma. Dopamine transport imaging demonstrated significant dopaminergic denervation in the right caudate and putamen. The degree of striatal dopamine transporter deficiency was more severe than expected in a patient with Parkinson disease. A trial of dopaminergic agent resulted in significant improvement of the tremor and associated symptoms. Interruption of the nigrostriatal pathway can occur in cases of HT because of midbrain peduncular lesion. The striatal dopaminergic function imaging may have a role in assessing presynaptic dopamine dysfunction and guiding treatment.