Tremor Distribution and the Variable Clinical Presentation of Essential Tremor

In addition to having postural and kinetic tremor of the upper limbs, some patients with essential tremor (ET) may have head tremor as well as cognitive and psychiatric disorders. We aimed to investigate whether the variable clinical presentation in ET patients, including motor and non-motor symptoms, differs in patients with and without head tremor. We consecutively enrolled 70 patients with a diagnosis of ET. Tremor severity was assessed by means of clinical rating scales. Patients also underwent kinematic recordings of postural and kinetic tremor of the upper limbs based on an optoelectronic system. Several neuropsychological tests were also administered. Finally, we adopted the structured interviews for DSM-IV, SCID-I, and SCID-II to investigate psychiatric and personality disorders. ET patients with upper limb tremor plus head tremor exhibited more severe kinetic tremor of the upper limbs and a higher occurrence of axis I psychiatric disorders than ET patients with upper limb tremor only. Cognitive and other motor and psychiatric features did not differ significantly with respect to tremor distribution. The study findings support the hypothesis that body tremor distribution, i.e., the presence of head tremor, influences the variable clinical presentation of ET. The study results support the notion that cases with head tremor may represent a distinct ET subtype, characterized by a prominent cerebellar involvement, and that psychiatric disorders should be considered as a specific manifestation of ET.