Objective: To study the clinical characteristics of a large single-centre cohort of patients with Orthostatic Tremor (OT)

Background: OT is a rare but disabling condition characterised by the presence of a tremor of 13-18 Hz in the legs upon standing or weightbearing. Diagnosis is often delayed due to under-recognition of its symptoms, and treatment responses are often suboptimal. Here we report the clinical characteristics of one of the largest cohorts of OT patients reported in literature.

Method: Clinical records of 82 consecutive OT patients were reviewed.

Results: 62.2% of the OT patients were women, in keeping with the female preponderance reported in the literature. The average age of onset was 50.3±16.2 years (mean ± SD); while the time from symptoms onset to diagnosis was 8.1±9.7 yrs. The average disease duration was 14.7±11.5 yrs. 65.8% of patients had EMG study of leg tremor frequency on standing, and the mean frequency was 14.6±3.4 Hz. Psychiatric co-morbidity was common, with 26.8% suffering from anxiety and/or depression. 60 patients had structural brain imaging and 20 had dopamine transporter SPECT, and they were all normal. One patient was classified as having secondary OT as the symptoms started after Tacrolimus exposure. 29.5% of patients reported an improvement of their tremor to alcohol. 40.2% of patients reported a benefit to Benzodiazepines (28 Clonazepam, 3 Alprazolam, 2 Diazepam), compared with 11.0% to Gabapentin, 9.8% to Primidone. 19.5% reported no benefit to any medications. None of the patients received neurosurgical intervention. 46.3% of patients reported significant disability due to OT. 27.4% of patients required regular use of walking aids while 23.3% of patients needed a carer.

Conclusion: The characteristics of our cohort are largely consistent with those reported in other large series of OT patients reported in literature [1,2]. Additionally, we also highlighted the delayed diagnosis experienced by many patients. Significant disability was reported by many patients and there was also a high incidence of psychiatric co-morbidity. Due to the retrospective nature of the study, we were unable to ascertain if the latter were due to disability arising from OT. Benzodiazepines were the drug that most OT patients in our series responded to, though pharmacological treatments generally were inadequate to control the symptoms of most patients. There is a pressing need to develop a clinical rating scale for OT and better treatment for these patients.

References: [1] Ganos et al. J Neurol Neurosurg Psychiatry. 2016; 87(2): 167-72 [2] Hasan et al. Neurology. 2016; 86(5): 458-64

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MDS Abstracts - https://www.mdsabstracts.org/abstract/orthostatic-tremor-a-case-series/