Somatosensory temporal discrimination threshold does not discriminate between patients with essential and dystonic head tremor
Abstract
Aim: The aim of this study was to evaluate the utility of the somatosensory temporal discrimination threshold (STDT) examination in patients with head tremor to differentiate between patients with essential tremor (ET) and dystonic head tremor in cervical dystonia (CD). Patients and methods: 42 patients with head tremor (21 ET and 21 CD patients) and 20 healthy controls (HC) were examined.
Patient examination consisted of medical history (onset of symptoms, family history, and eff ect of alcohol) and scales that objectively assessed head and upper limb tremor, severity of CD and severity of ataxia. All subjects were examined by STDT.
This is a method based on determining the shortest interval in which an individual recognizes two tactile stimuli as temporally separated. Results: No significant differences were found between ET and CD patients in medical history data.
On rating scales, the two groups of patients differed significantly, with ET patients having a higher severity of upper limb tremor and CD patients having a higher degree of dystonia (P < 0.0001). Both groups of patients had a higher degree of ataxia, signifi cantly more in patients with ET (P = 0.0008).
STDT values were significantly higher in patients with ET vs. HC (P = 0.0067).
We did not find major differences when comparing groups of patients with ET and CD. Conclusion: In patients with head tremor, abnormally elevated STDT values were observed in patients with ET but not in CD, probably due to impaired somatosensory stimulus processing mechanisms and time perception attributed to cerebellar involvement.
However, we did not find a significant difference in the STDT values when comparing the examined groups of patients