Clinical Features, Neuroimaging, and Levodopa-Responsiveness in Holmes' Tremor: A Video-Based Case-Series with a Review of the Literature.

Background: Holmes' tremor (HT) is a low-frequency tremor characterized by a combination of rest, posture, and action components. We are reporting the clinical features, neuroimaging findings, and levodopa responsiveness in 12 patients with HT. Cases: The majority of the patients were male (11/12). Dystonia was observed in 10 patients and the remaining two patients had head tremor, a "forme-fruste" of cervical dystonia. The underlying etiologies were vascular (n = 8), head trauma (n = 2), and tumor resection (n = 2). Neuroimaging showed isolated involvement of the midbrain in four, thalamus in two, and basal ganglia and cerebellum in one patient each. A combination of the lesion (thalamus and cerebellum = 2; cerebellopontine angle = 1, and cortical/subcortical = 1) was present in four patients. Levodopa responsiveness was seen in 75% of patients including one with levodopa-induced dyskinesia. Literature Review: Of 139 patients from 49 studies, levodopa was tried in 123 patients. Improvement with levodopa was seen in 71 patients (57.72%). No improvement with levodopa was observed in 33 patients (26.82%) and details regarding therapeutic response were unavailable in 19 patients (15.44%). Conclusions: Dystonia is an important clinical manifestation of HT. Levodopa responsiveness seen in the majority of the patients is consistent with the hypothesis that nigrostriatal pathway damage is crucial for the pathophysiology of HT.