Supine head tremor: a clinical comparison of essential tremor and spasmodic torticollis patients.

BACKGROUND: Essential tremor (ET) is among the most misdiagnosed neurological diseases, and overdiagnosis is especially common. As many as 30-50% of supposed 'ET' cases have other diagnoses, with dystonia prominent among these. Therefore, the recognition of differences in tremor phenomenology has potential diagnostic value for practising clinicians. There is an anecdotal sense that head tremor in ET is positional rather than resting, a feature which could aid in the diagnosis, yet no published data exist. METHODS: In this cross-sectional study of ET and spasmodic torticollis (ST) patients (3:1 matching) who had head tremor while upright, the prevalence of supine (ie, resting) head tremor was compared. RESULTS: There were 60 ET cases and 19 ST cases with head tremor while seated. When supine, head tremor persisted in only 5/60 (8.3%) ET versus 13/19 (68.4%) ST cases (p<0.001), indicating that essential head tremor is more likely to resolve in the supine position than is the head tremor of ST. Supine head tremor, when present in ET, did not seem to preferentially occur in patients with more severe disease (p>0.05). CONCLUSIONS: These results indicate that there is some validity to the anecdotal sense that head tremor in ET is a postural tremor that dissipates when a patient lies down; by contrast, in ST, head tremor more often persists. In a clinical context, these results have potential implications in diagnostically ambiguous patients with head tremor. Physicians should consider asking their tremor patients to lie down to assess whether head tremor resolves.

Estimating annual rate of decline: prospective, longitudinal data on arm tremor severity in two groups of essential tremor cases.

BACKGROUND: Despite its high prevalence, there are surprisingly few prospective, longitudinal data on the clinical course of essential tremor (ET). Patients themselves often want to know from their treating physician whether and by how much their tremor is expected to worsen over time. METHODS: As part of two research protocols, prospective, longitudinal data were collected on tremor severity in two samples of ET cases (44+39 cases, combined n=83). At a baseline and one follow-up evaluation, a detailed clinical assessment was performed and action tremor in the arms was rated by a senior movement disorders neurologist using a standardised clinical rating scale (Total Tremor Score (TTS), range 0-36). RESULTS: In the first case sample, TTS increased annually by 0.32 ± 0.89 points (ie, an annual increase of 5.3 ± 17.1% (median 1.8%) from the mean baseline score). TTS increased by ≥ 0.5 points in 23/24 (95.8%) cases followed for ≥ 5 years. In the second sample, TTS score increased annually by 0.64 ± 1.49 points (annual increase of 3.1 ± 8.1% (median 2.0%) from the mean baseline score). TTS increased by ≥ 0.5 points in 11/15 (73.3%) cases followed for ≥ 5 years. No baseline factors were identified that predicted annual change in TTS. CONCLUSIONS: Most ET cases exhibited a progressive worsening in tremor scores with time such that the average annual increase in tremor severity from baseline was estimated to be between 3.1% and 5.3% and the median annual increase from baseline was between 1.8% and 2.0%. These published estimates will hopefully be a useful prognostic guide for clinicians and their patients.

Rest tremor in advanced essential tremor: a post-mortem study of nine cases.

BACKGROUND: Rest tremor may occur in as many as 30% of essential tremor (ET) patients. It is not clear whether this tremor is a sentinel marker for brainstem Lewy body pathology. Here we report the clinical and post-mortem findings of nine ET cases with upper-extremity rest tremor in the absence of other parkinsonian features. METHODS: All brains had a complete neuropathological assessment. Tissue sections from the brainstem and basal ganglia were immunostained with α-synuclein antibody. RESULTS: All cases had longstanding ET (median duration=42 years) with moderate to severe arm tremor. Rest tremor involved both arms in seven (77.8%) cases and one arm in two cases. The rest tremor score was correlated with the total action tremor score (r=0.69, p=0.04). The number of torpedoes was elevated, and Purkinje cells, reduced. Post-mortem changes in the substantia nigra pars compacta (SNc), caudate, putamen and globus pallidum were minimal, and neither Lewy bodies nor Lewy neurites were evident. CONCLUSIONS: In nine ET brains with upper-extremity rest tremor, neither Lewy body-containing neurons nor Lewy neurites were found on α-synuclein immunostained sections, and other pathological changes in the basal ganglia were minimal. These data support the notion that isolated rest tremor in longstanding ET is not the expression of underlying Lewy body pathology in the SNc.