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TITLE: Surgical treatment of essential tremor.
AUTHORS: Pahwa R; Lyons K; Koller WC
AUTHOR AFFILIATION: Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
SOURCE: Neurology 2000;54(11 Suppl 4):S39-44
CITATION IDS: PMID: 10854351 UI: 20312906
ABSTRACT: Surgical treatment for essential tremor (ET) has been used since the early 1950s. Initially, different areas were targeted for tremor control. However, the optimal target was eventually determined to be the ventralis intermedius (VIM) nucleus of the thalamus. Thalamotomy improves contralateral tremor in more than 90% of patients. Long-term studies of thalamotomy indicate that the benefits continue in most patients. Persistent morbidity associated with thalamotomy, which occurs in less than 10% of patients, includes dysarthria, dysequilibrium, weakness, and cognitive impairment. Bilateral thalamotomy is associated with substantial morbidity and is usually avoided. Studies demonstrate that chronic stimulation of the VIM is safe and effective for tremor. Adverse effects of chronic stimulation include paresthesia, dysarthria, dysequilibrium, and localized pain. In many patients, bilateral thalamic stimulation is performed without a substantial increase in morbidity. ET patients with disabling medication-resistant tremor are reasonable candidates for these stereotactic procedures.

2000/07
2000/08 11:00

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TITLE: Pharmacologic treatment of essential tremor.
AUTHORS: Koller WC; Hristova A; Brin M
AUTHOR AFFILIATION: Department of Neurology, University of Miami School of Medicine, Miami, Florida 33136, USA.
SOURCE: Neurology 2000;54(11 Suppl 4):S30-8
CITATION IDS: PMID: 10854350 UI: 20312905
ABSTRACT: Essential tremor (ET) is a common movement disorder that often causes functional disability, potentially leading to physical and emotional difficulties. The paucity of data available regarding the underlying pathophysiologic mechanism of ET hinders the development of innovative approaches to pharmacotherapeutic treatments. Options for drug therapy include the use of primidone, beta-adrenergic blockers, such as propranolol, alcohol, and other drugs, such as benzodiazepines, gabapentin, carbonic anhydrase inhibitors, clozapine, flunarizine, clonidine, and the methylxanthine derivative theophylline. Chemodenervation with botulinum toxin type A may be a therapeutic option for selected patients with ET. Each drug is classified as to the quality of evidence for efficacy and the suggested strength of therapeutic recommendation. In general clinical practice, primidone and propranolol have proven efficacy in ET.

2000/07
2000/08 11:00

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TITLE: Chronic intracerebral stimulation and abnormal movements: why and when? Major therapeutic advances in the 90s
VERNACULAR TITLE: Stimulation intracerebrale chronique et mouvements anormaux: pourquoi et comment? Une avancee therapeutique majeure des annees 90.
AUTHORS: Caparros-Lefebvre D
AUTHOR AFFILIATION: Service de Neurologie, CHU, Pointre a Pitre. lefebvdo@ais.gp
SOURCE: Presse Med 2000 Apr 8;29(13):731-6
CITATION IDS: PMID: 10797828 UI: 20258163
ABSTRACT: TECHNICAL ASPECTS: Surgical procedures for abnormal movements progressively evolved toward microinvasive techniques performed under stereotaxic control. The next advance was the development of well-tolerated intracerebral stimulation with reversible effects. The quality of the results depends on optimal definition of the stimulation target. Optimally, the surgical protocol includes stereotaxic ventriculography to identify targets followed by electrical activity recordings of the structures crossed by the electrode. Finally, a minute study of the stimulation effects is performed under sterotaxic control while the patient is awake.

PARKINSON'S DISEASES: Indications for thalamic stimulation in Parkinson's disease have given way to subthalamic stimulation which improves tremor, bradykinesia and rigidity simultaneously. This result confirms the implication of the subthalamic nucleus in the pathogenesis of Parkinson syndromes. The palladium may be stimulated in Parkinson's patients with major iatrogenic involuntary movements.

ESSENTIAL TREMOR: Thalamic stimulation is indicated for essential tremor. The efficacy of chronic stimulation is currently under evaluation in other indications.

2000/06
2000/08 09:00


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TITLE: Neuropsychological functioning in a patient with essential tremor with and without bilateral VIM stimulation.
AUTHORS: Lucas JA; Rippeth JD; Uitti RJ; Shuster EA; Wharen RE
AUTHOR AFFILIATION: Department of Psychology, Mayo Clinic Jacksonville, FL 32224, USA.
SOURCE: Brain Cogn 2000 Mar;42(2):253-67
CITATION IDS: PMID: 10744923 UI: 20211270
ABSTRACT: The effects of deep brain stimulation on motor functions, cognitive abilities, and mood were assessed in an 80-year-old, right-handed male with a chronic history of essential tremor. Electrodes were implanted bilaterally in the ventral intermediate nucleus of the thalamus during a single operation. Upon evaluation at 3 months postsurgery, bilateral stimulation was associated with a clinically significant reduction in tremor ratings and improvement in manual dexterity. At that time, a battery of neuropsychological measures was administered with and without bilateral stimulation. The patient demonstrated comparable performances on measures of visuospatial perception, attention, mental tracking, verbal learning, and verbal recognition memory in both the "on" and "off" conditions. Without stimulation, the patient demonstrated declines of greater than 1 SD on measures of verbal fluency and verbal recall compared to when the stimulators were active. Responses to mood rating scales also indicated greater subjective distress without stimulation. Results are discussed in the context of previous studies of the effects of thalamic stimulation on neurocognitive functioning. Copyright 2000 Academic Press.

2000/05
2000/16 09:00

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TITLE: Effect of low and high frequency thalamic stimulation on sleep in patients with Parkinson's disease and essential tremor.
AUTHORS: Arnulf I; Bejjani BP; Garma L; Bonnet AM; Damier P; Pidoux B; Dormont D; Cornu P; Derenne JP; Agid Y
AUTHOR AFFILIATION: Centre d'Investigation Clinique, Federation de Neurologie and INSERM U 289, Paris, France. isabelle.arnulf@psl.ap-hop-paris.fr
SOURCE: J Sleep Res 2000 Mar;9(1):55-62
CITATION IDS: PMID: 10733690 UI: 20198509
ABSTRACT: Continuous high frequency stimulation of the ventral intermediate nucleus of the thalamus (Vim), delivered through surgically implanted quadripolar electrodes, alleviates tremor in Parkinson's disease (PD) and essential tremor (ET). The Vim is adjacent to the thalamic reticular nuclei, where sleep spindles originate according to animal models. In order to determine whether Vim stimulation affects sleep spindles, six patients (4 PD, 2 ET), aged 60-69 years, were recorded on a control night and a stimulation night (130 Hz, 2-3 V; right stimulation in five patients and bilateral stimulation in one patient). Stimulation did not modify sleep quality or architecture. Sleep spindles were present and symmetrical in five out of six patients under stimulation. However, in one patient with a sustained 'thalamotomy-like effect' that abolished tremor, spindles were asymmetrical even without stimulation. In each patient, spindle density was similar on both nights (mean+/- SEM: 2.25+/-0. 61 spindles per min of stage 2 sleep vs. 1.84+/-0.31). In an attempt to promote sleep two different patterns of stimulation were applied in the region of ventrooralis posterior and reticularis nuclei in five patients in the awake state. Continuous low frequency stimulation (5 Hz, 0.1 V), and repeated trains of 15 Hz for 1 s every 15 s mimicking the pattern of physiological spindles, each failed to induce sleep or cortical synchronization. We conclude that Vim stimulation, unlike thalamotomy, selectively reduces tremor without altering sleep or sleep spindles. Our results also suggest that low frequency stimulation applied in the region of the reticular nuclei does not induce sleep.

2000/06
2000/03 09:00

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TITLE: A comparison of continuous thalamic stimulation and thalamotomy for suppression of severe tremor [see comments]
AUTHORS: Schuurman PR; Bosch DA; Bossuyt PM; Bonsel GJ; van Someren EJ; de Bie RM; Merkus MP; Speelman JD
AUTHOR AFFILIATION: Department of Neurology, Academic Medical Center, Amsterdam, The Netherlands.
SOURCE: N Engl J Med 2000 Feb 17;342(7):461-8
CITATION IDS: PMID: 10675426 UI: 20125069
COMMENT: Comment in: N Engl J Med 2000 Feb 17;342(7):505-7
ABSTRACT: BACKGROUND: Deep-brain stimulation through an electrode implanted in the thalamus was developed as an alternative to thalamotomy for the treatment of drug-resistant tremor. Stimulation is thought to be as effective as thalamotomy but to have fewer complications. We examined the effects of these two procedures on the functional abilities of patients with drug-resistant tremor due to Parkinson's disease, essential tremor, or multiple sclerosis.

METHODS: Sixty-eight patients (45 with Parkinson's disease, 13 with essential tremor, and 10 with multiple sclerosis) were randomly assigned to undergo thalamotomy or thalamic stimulation. The primary outcome measure was the change in functional abilities six months after surgery, as measured by the Frenchay Activities Index. Scores for this index can range from 0 to 60, with higher scores indicating better function. Secondary outcome measures were the severity of tremor, the number of adverse effects, and patients' assessment of the outcome.

RESULTS: Functional status improved more in the thalamic-stimulation group than in the thalamotomy group, as indicated by increases in the score for the Frenchay Activities Index (from 31.4 to 36.3 and from 32.0 to 32.5, respectively; difference between groups, 4.4 points; 95 percent confidence interval, 2.0 to 6.9). After adjustment for base-line characteristics, multivariate analysis also showed that the thalamic-stimulation group had greater improvement (difference between groups, 5.1 points; 95 percent confidence interval, 2.3 to 7.9). Tremor was suppressed completely or almost completely in 27 of 34 patients in the thalamotomy group and in 30 of 33 patients in the thalamic-stimulation group. One patient in the thalamic-stimulation group died perioperatively after an intracerebral hemorrhage. With the exception of this incident, thalamic stimulation was associated with significantly fewer adverse effects than thalamotomy. Functional status was reported as improved by 8 patients in the thalamotomy group, as compared with 18 patients in the thalamic-stimulation group (P=0.01).

CONCLUSIONS: Thalamic stimulation and thalamotomy are equally effective for the suppression of drug-resistant tremor, but thalamic stimulation has fewer adverse effects and results in a greater improvement in function.

2000/02
2000/26 09:00

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TITLE: Efficacy of unilateral deep brain stimulation of the VIM nucleus of the thalamus for essential head tremor.
AUTHORS: Koller WC; Lyons KE; Wilkinson SB; Pahwa R
AUTHOR AFFILIATION: Department of Neurology, University of Kansas Medical Center, Kansas City 66160-7314, USA.
SOURCE: Mov Disord 1999 Sep;14(5):847-50
CITATION IDS: PMID: 10495050 UI: 99423241
ABSTRACT: Essential tremor is a common movement disorder. Deep brain stimulation of the VIM nucleus of the thalamus has been reported to be efficacious for reducing essential hand tremor. The effect of deep brain stimulation of the thalamus on essential head tremor has not been well studied. Therefore, we evaluated the effect of DBS of the thalamus in 38 patients with essential head tremor. Head tremor scores prior to surgery were compared with scores at 3, 6, and 12 months postimplant with stimulation "on" and "off." The 3-month evaluations were blinded for 24 patients and all others were open-label. There was a significant improvement in head tremor at all postimplant evaluations compared with baseline. Essential head tremor can be reduced with deep brain stimulation of the VIM nucleus of the thalamus and, pending the results of other controlled trials, should be considered as a treatment option for patients with disabling essential head tremor unresponsive to medication.

1999/09
1999/24 09:00

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TITLE: The initial treatment of Parkinson's disease should begin with levodopa.
AUTHORS: Weiner WJ
AUTHOR AFFILIATION: Department of Neurology, University of Miami School of Medicine, Florida 33136, USA.
SOURCE: Mov Disord 1999 Sep;14(5):716-24
CITATION IDS: PMID: 10495031 UI: 99423222
ABSTRACT: For over two decades controversy has surrounded the initial choice of therapeutic agent for patients with early symptomatic Parkinson's disease. Whether levodopa or dopamine receptor agonist monotherapy in these patients is more efficacious and/or results in fewer long-term complications of dopaminergic therapy such as motor fluctuations, dyskinesias, or psychiatric disorders is unresolved. This article examines the evidence related to levodopa-sparing strategies and levodopa-induced toxicity in Parkinson's disease. At this time, there is little evidence to support levodopa-sparing strategies or to suggest that levodopa is toxic and harmful to patients with Parkinson's disease.

1999/09
1999/24 09:00


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Arch Neurol 2000 Aug;57(8):1194-8

Clinical subtypes of essential tremor.

Louis ED, Ford B, Barnes LF
Neurological Institute, Unit 198, 710 W 168th St, New York, NY 10032, USA.
BACKGROUND: There is clinical variability in essential tremor (ET), but it is not clear whether this variability is because of the existence of distinct clinical subtypes of ET (ie, forms of ET that may differ in their etiology, rate of progression, or response to treatment).

OBJECTIVES: To examine in a group of ET cases the age of onset, anatomic distribution, and rate of progression of tremor, and to look for associations between these factors.

METHODS: Cases of ET were ascertained from a community (n = 60) and a tertiary referral clinic (n = 55) in northern Manhattan, New York, NY. All subjects underwent an interview and videotaped tremor examination. Rate of progression was estimated based on the tremor severity and reported disease duration at the time of evaluation.

RESULTS: Age of onset was bimodally distributed in clinic cases. There were differences in the anatomic distribution of the tremor (arm tremor only vs head and arm tremor vs isolated head tremor). Rate of progression was distributed exponentially; there was a large cluster of subjects with slower rates of progression, and a smaller number who had faster rates. There was an association between age of onset and rate of progression (r = 0.46-0.50, P<.002); cases with older age of onset (>60 years) progressed more rapidly (P<.001). In addition, upper limb tremor progressed more slowly among those with concomitant head tremor (P =.03).

CONCLUSIONS: Essential tremor is not a homogeneous condition. There are differences in age of onset, anatomic distribution of tremor, and rate of progression. The ET in several groups of patients in this study (those with age of onset >60 years and those without head tremor) progressed more rapidly, suggesting that these ET cases may define distinct clinical subtypes. These subtypes should be further assessed for etiologic and genetic heterogeneity as well as differences in responsiveness to therapeutic agents.

Arch Neurol. 2000;57:1194-1198

PMID: 10927801, UI: 20386855

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