Imaging essential tremor

To investigate over time changes in striatal dopamine transporter (DAT), we performed two sequential N‐ω‐fluoropropyl‐2β‐carbomethoxy‐3β‐(4‐iodophenyl) tropane single photon computed tomography (SPECT) scans in 20 subjects with essential tremor (ET), in 13 with Parkinson disease (PD) and in 23 healthy controls (HC, one scan only). We also performed an [^99mTc]ethyl cysteinate dimer bicisate SPECT exam for regional brain network analysis in 9 ET, in a second group of 18 PD (9 with tremor, tPD and 9 akinetic‐rigid dominant, arPD) and in 8 HC. PD subjects had a reduced DAT binding in comparison to ET and HC with an annual decline rate of 7.3% in the contralateral putamen. There were no mean uptake differences between ET and HC at baseline and no uptake loss over time in ET. A discriminant analysis grouped 30% (first scan) and 5% (second scan) of ET as PD and a partition analysis showed overlap between ET and PD for caudate nucleus uptake. Spatial covariance analysis revealed that the expression of the PD‐related regional pattern separated both tPD and arPD from ET and HC. In conclusion, PD and ET do not share a common pattern of dopaminergic loss over time. However, mild impairment of dopamine transporter in the caudate nucleus may contribute to tremor onset in ET. © 2010 Movement Disorder Society     

Management of essential tremor

Essential tremor (ET) is the most prevalent tremor syndrome. It commonly affects the hands, head, voice, and other body parts. Appropriate management begins with correct diagnosis. Primidone and propranolol are the first-line medications for the treatment for ET, but several other medications may also provide benefit. In patients with medically refractory tremor, alternative therapies, including surgery or injections of botulinum toxin, may be considered.     

Topography of essential tremor

IntroductionTopography of tremor manifestations is poorly investigated in essential tremor. The present study explores the prevalence and clinical correlates of head and/or voice tremor in essential tremor.MethodsOut of a prospectively designed registry of 972 patients, 884 patients with definite and probable essential tremor had complete information on tremor localization. Demographic and clinical characteristics were compared among four subgroups: group A (without head or voice tremor, n = 619), B (with head but without voice tremor, n = 155), C (with voice but without head tremor, n = 47), and D (with both head and voice tremor, n = 63).ResultsIn our patients, total prevalence of tremor was 24.7% for head, 12.4% for voice and 7.1% for the combination of head and voice. Logistic regression analyses showed that female gender is strongly associated with head tremor, which was confirmed by an additional meta-analysis. Severe hand tremor was the only factor associated with voice tremor. Both female gender and severe hand tremor increase the odds for having the combination of head and voice tremor. For males, hand tremor severity is significantly increased among those with head and voice tremor alone and in combination, but for females only for the combination. Patients with both head and voice tremor have more frequent involvement of legs and other localizations and are less responsive to β-blockers.ConclusionsFemale gender and severe hand tremor may increase the odds of head and/or voice tremor in essential tremor. The association of hand tremor severity with midline tremor is stronger for males than females.     

Phenobarbitone in essential tremor

We conducted a double-blind, placebo-controlled trial of phenobarbitone on a fixed-dose regimen in 12 patients with essential tremor. The drug was better than placebo on accelerometric measurement and clinical assessment, but not according to patient self-assessment or measures of manual performance. Phenobarbitone may be an alternative to beta-adrenoreceptor antagonists in treating essential tremor.     

Quetiapine and essential tremor

The safety and tolerability of quetiapine (up to 75 mg/day) as monotherapy on essential tremor were investigated in an open-label study in 10 patients. Five men and 5 women, with a mean age of 66.3 years, affected by essential tremor participated in the trial. They were treated with increasing doses of quetiapine to 75 mg/day over a 6-week period. Side effects included a paradoxical psychiatric reaction in one and anger in another, and in both cases quetiapine was discontinued. In two other patients, somnolence led to dose reduction. There were no pre- versus post-treatment differences, but 3 out of 10 patients benefited (improvement >20%). Although the study was not powered to assess efficacy, quetiapine seems to be a safe drug for the treatment of essential tremor.     

Pathology in essential tremor

The pathology of essential tremor (ET) is increasingly being studied. The main findings include a reduction in cerebellar Purkinje cells, other pathological changes of cerebellar degeneration and restricted Lewy bodies in the locus ceruleus. This paper will review those findings and put them into context with clinical studies in ET and findings in neurodegenerative disorders such as Parkinson's disease.     

Primidone and essential tremor

Summary To clarify whether primidone itself, and not only its metabolite phenobarbitone, suppresses essential tremor, the effect of a high single dose of primidone was tested. Of 11 patients, 8 showed a reduction of their tremor by 54%–69% for up to 28h. The serum concentration of primidone was as expected, whereas those of the metabolites phenyl-ethylmalonamide and phenobarbitone were very low. The tremor suppression can thus be considered to be an effect of primidone. Three of the 11 patients did not show a reduction of tremor.     

Orthostatic tremor: an association with essential tremor

Orthostatic tremor is characterized by tremor of the trunk and legs while standing. Rapid frequency has been emphasized as an important criterion for the diagnosis of this tremor. We observed five patients who had the typical findings of orthostatic tremor but had a wide range of frequencies. All five also had postural hand tremor and a family history of essential tremor, suggesting a relationship between orthostatic tremor and essential tremor. This report also emphasizes the association of orthostatic tremor with painful cramps and a relatively consistent improvement with clonazepam.     

Handedness and essential tremor

In patients with essential tremor, a direct relationship was found between hand dominance and severity of hand tremor. A higher incidence of left-handedness was found in patients with essential tremor than in controls.     

Physiologic and essential tremor

We studied physiologic and essential hand tremor using inertial loading; hand acceleration and forearm EMG data were analyzed by auto- and cross-spectral analysis. Early essential tremor was qualitatively similar to the 8- to 12-Hz component of physiologic tremor, suggesting that this tremor component is a forme fruste of essential tremor. Advanced essential tremor had a frequency of 4 to 8 Hz. Patients with tremor frequencies in both ranges were observed in each of 10 families. In antagonistic forearm muscles, both synchronous and alternating tremor bursts were observed in 11 of 44 patients. Essential tremor should not be classified solely on the basis of frequency or EMG pattern.     

Orthostatic tremor: an essential tremor variant?

Three patients with a clear-cut history of essential tremor of the upper limbs presented with the clinical features reported by Heilman as orthostatic tremor. Electromyographic findings included 6-8 Hz postural tremor in all four limbs. Highly synchronized 16 Hz rhythmic discharges were found in the legs upon standing. This peculiar pattern of discharge was also observed in the upper limbs and spinal muscles. High frequency rhythmic bursts, either alternating or co-contracting were present in specific postures not necessarily related to standing. An additional group of 12 patients with postural tremor of the legs was studied; seven of these showed modification in the frequency and synchronization of the muscle discharges upon standing. Although none of them had the full-blown clinical syndrome of orthostatic tremor, they complained of mild unsteadiness upon standing, together with a vague sensation of stiffness in the lower limbs. The present findings induce us to think that there might be a link between essential tremor and the so-called orthostatic tremor. Orthostatic tremor might be an essential-tremor-related entity that may be caused by a derangement in the central mechanism in charge of the organization of certain motor activities, not necessarily controlling the standing position.     

Clinical manifestations of essential tremor

A clinical study of 42 patients with essential tremor is presented. In the case of 12 patients the family history strongly suggested an autosomal dominant mode of transmission, in four the mode of inheritance was indeterminate, and the remaining 26 patients were sporadic cases without an established genetic basis. The tremor involved the upper extremities in 41 patients, the head in 25, lower limbs in 15, and trunk in two. Seven patients showed involvement of speech. Variations were found in the speed and regularity of the tremor. Leg involvement took a variety of forms: (1) direct involvement by tremor; (2) a painful limp associated with forearm tremor; (3) associated dyskinetic movements; (4) ataxia; (5) foot clubbing; and (6) evidence of peroneal muscular atrophy. Several minor symptoms—hyperhidrosis, cramps, dyskinetic movements, and ataxia—were associated with essential tremor. Other features were linked phenotypically to the ataxias and system degenerations. Apart from minor alterations in tone, expression, and arm swing, features of Parkinsonism were notably absent.     

特发性震颤的临床特点分析

目的探讨特发性震颤（essential tremor,ET）的临床特点。方法回顾性分析98例ET患者的临床资料。结果98例ET中男56例,女42例。发病年龄6～72岁,平均43．08±18．18岁。病程1～48年,平均14．04±11．39年。48例（48．98％）患者有阳性家族史。临床主要表现为单症状的姿势性震颤,累及部位依次为手98例（100％）、头38例（38．78％）、下肢28例（28．57％）、咽喉部16例（16．33％）、下颏10例（10．20％）等。64例患者做了饮酒试验,其中58例（90．63％）有酒精反应。84．62％的患者服用盐酸阿罗洛尔治疗有效。结论特发性震颤的临床表现以单症状姿势性震颤为主,手及头部受累明显,多数患者对酒精有反应,盐酸阿罗洛尔治疗有效。