Longitudinal evaluation of patients with isolated head tremor

Introduction: Isolated head tremor, a pathological condition characterized by head tremor without dystonic postures or tremor in other body parts, has recently been suggested to be a form of dystonia. It is however still unclear whether isolated head tremor precedes dystonia or remains unmodified overtime. Methods: We enrolled 20 patients with isolated head tremor. For each patient, we assessed videos recorded at enrollment and after 5 years. The videotapes were reviewed by two independent experienced movement disorder specialists who evaluated and scored tremor and CD severity using the Fahn-Tolosa-Marin Clinical Rating Scale for Tremor and the revised Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), respectively. Results: Upon enrollment, all 20 patients showed isolated head tremor. Mean tremor severity was 2.7 ± 0.9 as measured using the Fahn-Tolosa-Marin Clinical Rating Scale for Tremor total score. At the 5-year follow-up examination, 15 (75%) of the 20 patients with isolated head tremor showed dystonic postures in the neck, while the remaining 5 patients (25%) had only isolated head tremor. Mean severity of dystonia as measured using the TWSTRS-2 total score was 11.8 ± 3.6. Head tremor severity was unchanged between baseline and the 5-year follow-up examination (p > 0.05). At the follow-up examination, no patients had tremor or dystonia in a body part other than the neck, nor did they develop bradykinesia or other parkinsonian signs. Conclusions: Our longitudinal study demonstrated that patients with isolated head tremor may develop cervical dystonia over time.