Longitudinal evaluation of patients with isolated head tremor

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.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.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.Our longitudinal study demonstrated that patients with isolated head tremor may develop cervical dystonia over time.