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PubMed2000

The dynamics of resting and postural tremor in Parkinson's disease.

OBJECTIVE: The study examines the time and frequency structure of Parkinson's disease tremor in patients that exhibit no clinical signs of tremor. METHODS: Eight mild to moderate Parkinson's disease and 8 matched control subjects maintained their limb in a constant position (30 s) under a postural finger, postural hand and resting tremor condition. Finger acceleration from the middle phalange, electromyographic (EMG) activity from extensor digitorum communis and flexor digitorum superficialis (FDS) were recorded. RESULTS: The data confirmed that there were no differences in the amount of limb motion and the modal frequency was around 9 Hz for each subject group. The time-dependent organization of tremor was more regular (lower approximate entropy [ApEn]) in Parkinson's disease. Both time and frequency analyses between the acceleration and extensor EMG signals demonstrate a reduction in the 20-25 Hz tremor component and an increase in the 8-12 Hz region of tremor. CONCLUSIONS: The results are discussed in relation to the proposal that increased regularity results from an increase in motor unit synchronization at 8-12 Hz and a reduction in the amplitude of the 20-25 Hz tremor component. The time and frequency structure of tremor may be useful in assessing individuals with Parkinson's disease.

Aged↗
PubMed2002

Vim thalamotomy for Holmes' tremor secondary to midbrain tumour.

Holmes' (rubral or midbrain) tremor is an unusual combination of 2 Hz to 5 Hz rest, postural, and kinetic tremors of an upper extremity. This tremor has been considered to result from the lesions in the vicinity of the red nucleus in the midbrain. There has been no systematic analysis of the surgical target in the Holmes' tremor so far of nucleus ventrointermedius (Vim) or globus pallidus interna. This 26 year old man gradually developed a disabling midbrain tremor involving both the distal and proximal parts of the left upper arm. Additional neurological findings included oculomotor palsy and ataxia of the left arm. On the radiological studies, a mass lesion (germinoma) was found on the midbrain tegmentum, which was treated by conventional radiation therapy. Although there was improvement in the radiological imaging, his midbrain tremor became intolerable despite medical treatment. The authors performed MR guided stereotactic Vim thalamotomy. With radiofrequency lesioning in the right Vim, his resting, postural, and action tremors were much alleviated in both the distal and proximal parts of the left upper extremity. The authors consider that Vim thalamotomy is still an effective means of controlling midbrain tremors involving the proximal upper limb.

Adult↗
PubMed2000

A comparison of continuous thalamic stimulation and thalamotomy for suppression of severe tremor.

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.

Activities of Daily Living↗
PubMed2006

Topiramate in essential tremor: a double-blind, placebo-controlled trial.

BACKGROUND: Essential tremor is most prevalent and most disabling in older patients. Additional therapies are required for patients with an inadequate response or intolerable side effects. In small trials, topiramate appeared to be beneficial in essential tremor. METHODS: In this multicenter, double-blind, placebo-controlled, parallel-design trial, patients with moderate to severe essential tremor of the upper limbs were randomized to 24 weeks of treatment with placebo or topiramate (target dose, 400 mg/day) as monotherapy or as an adjunct to one antitremor medication. The primary efficacy variable was the final visit tremor score based on the Fahn-Tolosa-Marin Tremor Rating Scale (TRS). RESULTS: The intent-to-treat population was 208 patients (topiramate, 108; placebo, 100). The final visit score (last observation carried forward) was lower in the topiramate group than with placebo (p < 0.001). Mean percentage improvement in overall TRS scores was 29% with topiramate at a mean final dose of 292 mg/day and 16% with placebo (p < 0.001). Topiramate was associated with greater improvement in function and disability (p = 0.001). A between-group difference (p < 0.001) was observed at the first on-treatment visit at 4 weeks when the target topiramate dose was 100 mg/day (mean achieved dose, 62 +/- 9 mg/day). The most common treatment-limiting adverse events in topiramate-treated patients were paresthesia (5%), nausea (3%), concentration/attention difficulty (3%), and somnolence (3%). Adverse events were treatment limiting in 31.9% of topiramate patients and 9.5% of placebo patients. CONCLUSIONS: Topiramate was effective in the treatment of moderate to severe essential tremor. Tremor reduction was accompanied by functional improvements, such as in motor tasks, writing, and speaking.

Adult↗
PubMed1993

Thalamic stimulation and proximal tremor. A specific target in the nucleus ventrointermedius thalami.

The severe proximal cerebellar postural tremor (also called action or intention or hyperkinetic tremor) is barely influenced by thalamotomy or stimulation of the thalamus at the classic target in the lower part of the nucleus ventrointermedius thalami (VIM). In four patients with a severe postural distal and proximal tremor, an electrode fitted with four points of contact was introduced within the entire height of the VIM. In each patient, stimulation of the lower part of the VIM was most effective in the distal component of the tremor, whereas its proximal component was specifically reduced by stimulation of its upper part. These results indicate that (1) proximal postural tremors can be as much affected by stimulation of the VIM as distal tremors, (2) there is a somatotopy in the VIM that is similar to that in the nucleus ventralis posterolateralis thalami, and (3) it is possible with this technique to adjust the VIM stimulation site so as to obtain the maximum efficacy according to the locale of the tremor.

Adolescent↗
PubMed2003

The fragile X premutation presenting as essential tremor.

CONTEXT: The fragile X premutation has recently been reported to be associated with a neurodegenerative syndrome, chiefly characterized by intention tremor, gait ataxia, and executive cognitive deficits in men older than 50 years. Essential tremor is a frequent cause of tremor in elderly patients and in some cases is associated with impaired tandem gait and cognitive deficits. OBJECTIVE: To describe 2 fragile X carriers whose clinical presentation mimicked essential tremor. DESIGN: The 2 patients described herein underwent neurologic examinations by experienced movement disorders neurologists, magnetic resonance imaging, and fragile X gene, messenger RNA, and protein analyses. One underwent detailed neuropsychological testing. SETTING: Patients were studied at 2 large university movement disorders clinics. PATIENTS: Both patients were white men older than 50 years who had been diagnosed as having essential tremor and then found to be fragile X carriers. RESULTS: Besides disabling intention tremor, the 2 patients had impaired tandem, generalized brain atrophy, and unusual bilateral T2 middle cerebellar hyperintensities on magnetic resonance imaging. The patient who underwent neuropsychological testing had frontal executive deficits. Both patients had elevated fragile X mental retardation gene 1 messenger RNA and reduced fragile X mental retardation 1 protein levels. CONCLUSION: The fragile X carrier state may underlie the clinical findings in some older men diagnosed as having essential tremor.

Aged↗
PubMed2006

Common misdiagnosis of a common neurological disorder: how are we misdiagnosing essential tremor?

BACKGROUND: As a common neurological disorder, the diagnosis of essential tremor (ET) is considered routine. Despite this, previous work suggests that misdiagnoses may be common. Among other things, these misdiagnoses can lead to treatment errors. OBJECTIVES: To estimate how often other tremor disorders are misdiagnosed as ET and to identify factors that increase the odds of misdiagnosing ET and to precisely quantify the extent to which they do so. DESIGN: Seventy-one consecutive patients underwent an evaluation at the Neurological Institute of New York, New York, between January 1, 2000, and December 31, 2005; these patients had a pre-evaluation diagnosis of ET. The criteria for ET were adapted from the consensus statement of the Movement Disorder Society. RESULTS: Twenty-six patients (37%) were misdiagnosed as having ET ("false ET"). Their true diagnoses were Parkinson disease (11 patients [15%]), dystonia (6 patients [8%]), Parkinson disease with ET (5 patients [7%]), and other disorders (4 patients [6%]). Factors associated with misdiagnosed ET included unilateral arm tremor (odds ratio, 10.5; 95% confidence interval, 1.2-95.4; P=.02), spooning of the hands and other dystonic postures (odds ratio, 16.3; 95% confidence interval, 4.0-66.4; P<.001), and other unusual features (isolated thumb tremor, isolated leg tremor, and non-rhythmic tremor) (odds ratio, 49.4; 95% confidence interval, 2.7-895.0; P<.001). CONCLUSIONS: About 1 in 3 patients with tremor was misdiagnosed as having ET, with the most frequent false diagnoses being Parkinson disease and dystonia. Several factors that increased the odds of misdiagnosing ET were identified. These factors could be incorporated into improved diagnostic algorithms.

Adult↗
PubMed1997

Quantitative measurement of the effects of caffeine and propranolol on surgeon hand tremor.

OBJECTIVE: To quantitatively measure the effects of caffeine and propranolol, a nonselective beta-blocking agent, on surgeon hand tremor during simulated vitreoretinal microsurgery. METHODS: Seventeen ophthalmic surgeons were tested on 3 separate days. On each day, subjects ingested 200 mg of caffeine, 10 mg of propranolol hydrochloride, or gelatin placebo. The drugs were administered as part of a double-masked, placebo-controlled trial. Hand tremor was measured using the Microsurgery Advanced Design Laboratory Stability, Activation, and Maneuverability tester (MADSAM), a high-resolution, noncontact position tracking system. RESULTS: The average percent magnitude changes from baseline tremor measurements were +15%, +31%, and -22% for placebo, caffeine, and propranolol groups, respectively. Analysis of variance techniques accounting for effects of individuals, drugs, and day order demonstrated that only drug effects on percent magnitude change of tremor were statistically significant (P = .01, F test). Detailed comparisons of the 2 drug groups with the placebo group revealed that, after adjusting for individual and order effects, only the mean decrease in tremor due to ingestion of propranolol was a statistically significant trend (P = .03, F test). Although caffeine caused a larger mean increase in percent magnitude change in tremor than placebo, this trend was not statistically significant (P = .34, F test). The evaluation of systemic physiologic measurements showed that there were statistically significant drug effects on percent change in systolic (P < .001, F test) and diastolic (P = .002, F test) blood pressure and pulse rate (P = .002, F test). Individual and day order effects were not significant. No adverse side effects were observed or reported in our test subjects. CONCLUSION: Physiologic surgeon hand tremor can be decreased by the oral intake of a low dose of propranolol.

Adrenergic beta-Antagonists↗
PubMed1999

Involvement of cranial muscles and high intermuscular coherence in orthostatic tremor.

Electromyographic recordings were conducted from limb, trunk, and cranial muscles in 6 patients with orthostatic tremor. Spectral analysis revealed a high-frequency tremor not only in the muscles of the limbs and trunk, but also in cranial muscles. The cross spectra were analyzed between various pairs of muscles that displayed a high-frequency tremor pattern. The resulting peak correlations were uniformly very high (near one) suggesting a high level of coherence. The involvement of cranial muscles suggests that supraspinal mechanisms are involved in the generation of orthostatic tremor. The high intermuscular coherence between all muscles indicates the existence of either a unique oscillator that generates tremor in all involved muscles on both sides of the body or a linking mechanism probably at a supraspinal level. The high-frequency tremor was only found when the muscles were contracted isometrically, irrespective of body posture. Thus, tremor generation might be more closely linked to mechanisms responsible for isometric force control than to those involved in stance regulation.

Aged↗
PubMed1999

Natural course of combined limb and palatal tremor caused by cerebellar-brain stem infarction.

After infarction of the left superior cerebellar peduncle and dentate nucleus, a patient developed tremor of the left upper limb beginning on the twelfth day followed by palatal tremor appearing 10 months after infarction. Surface electromyogram revealed a difference in the frequency of the tremor in the upper limb and soft palate. When the palatal tremor appeared, brain magnetic resonance T2-weighted images revealed high signal intensity of the contralateral, right inferior olivary nucleus. Subsequently, when the amplitude of palatal tremor became less severe, the high olivary signal intensity subsided whereas the hypertrophy of the nucleus remained. This patient provides useful information on the pathogenesis of skeletal and palatal tremor with brain stem or cerebellar lesions based on the differences in the onset and frequency of tremors and morphologic changes in the inferior olive.

Arm↗
PubMed2000

Action tremor during object manipulation in Parkinson's disease.

In previous studies of fingertip forces during precision grip in subjects with Parkinson's disease (PD), we observed regular oscillations in isometric force. The present study characterizes the nature of these oscillations. Fingertip forces were recorded from the index finger and thumb during precision grip-lifts with a 300 g and 900 g object in 10 subjects with PD and 20 healthy control subjects. Fourier analysis confirmed that all subjects with PD exhibited force oscillations with a clearly definable frequency (approximately 7-11 Hz). Five of these subjects also exhibited a second lower frequency peak (approximately 5 Hz). Approximately half of the 20 control subjects displayed a single frequency peak (approximately 8-12 Hz), which was generally lower in amplitude than in the subjects with PD (representing enhanced physiological tremor), whereas the remaining control subjects had low-amplitude, broad-based spectra (representing physiological tremor). The amplitude of the force oscillations was higher for lifts with the heavier object in both the control subjects and subjects with PD. L-Dopa resulted in a decreased tremor amplitude but did not influence the frequency. The force oscillations of the two opposing digits normal to the grip surfaces were in phase, whereas the oscillations tangential to the grip surfaces were often out of phase. The results suggest that the multipeaked force rate trajectories reported previously are caused by action tremor. The similarity of force oscillations in subjects with PD and healthy control subjects suggests common tremor-generating mechanisms and supports the notion that the parkinsonian action tremor (AT) is an exaggerated form of physiological tremor. These findings provide insight into the impaired hand function observed in individuals with PD.

Adult↗
PubMed2001

Validation for tremor quantification of an electromagnetic tracking device.

An electromagnetic tracking system was used to record arm motion in subjects with Parkinson's disease (n = 23), essential tremor (n = 28) or without neurological disease (n = 4). Tremor magnitude was calculated by averaging the three-dimensional displacement of individual tremor bursts. Tremor magnitude calculated in this manner was quite closely correlated with a clinician's estimate (r = 0.88 and 0.86 for Parkinsonian and essential tremors, respectively) and was reproducible (r = 0.93 for repeated recordings). The accuracy of the device and algorithm was confirmed by mechanically generating oscillations of known magnitudes and frequencies. This device is adaptable for quantifying different types of tremors and its accuracy is easy to verify. Because position rather than acceleration is tracked, tremor amplitude can be stated in readily comprehensible units.

Adult↗
PubMed2004

Tremor induced by thalamic deep brain stimulation in patients with complex regional facial pain.

We report on two patients who developed a new postural and action tremor after chronic stimulation of the contralateral thalamus (VPM nucleus) during treatment of a complex regional facial pain syndrome. The tremor was only present during deep brain stimulation (DBS) and was suppressed with adjustment of the stimulation parameters. Tremor was seen only with low frequency stimulation (50 Hz or lower) and disappeared with higher stimulation frequencies. In addition to being an unusual side effect of thalamic DBS, we believe that this phenomenon affords insight into one possible mechanism underlying essential tremor (ET). A central oscillatory mechanism involving the olivocerebellar complex and the thalamus, which is a part of the cerebro-cerebello-cerebral circuit, is thought to play an important role in the genesis of ET. Induction of a tremor resembling ET in our patients indicates an active role for low frequency stimulation. A plausible explanation for this is that low frequency stimulation in the thalamic area enhances the output of the tremor-producing network. This leads credence to the concept of central oscillations in a "tremor circuit," of which the thalamus is a part, as being important in ET.

Adult↗
PubMed2006

Association between restless legs syndrome and essential tremor.

After observing that several families with essential tremor (ET) clinically cosegregated with restless legs syndrome (RLS), we prospectively evaluated for the presence of RLS in 100 patients presenting to the Baylor College of Medicine with ET and prospectively examined all patients presenting with RLS for the presence of tremor during the same time frame. Of 100 consecutive ET patients (60 women and 75 with a family history of ET) seen over 19 weeks (current age, 65.2 +/- 16.3 years; age at tremor onset, 37.8 +/- 19.9 years) 33 met all criteria for RLS, of which 25 had never been diagnosed previously. A family history of RLS was reported in 57.6% of these 33 patients and was the only significant predictor of RLS in the ET population. Their International Restless Legs Syndrome Rating Scale score was 16.6 +/- 8.1. Over 19 weeks, we also examined 68 consecutive RLS patients (63.2% women and 54.4% with a family history of RLS) for the presence of tremor. Their current age was 55.8 +/- 14.4 years, and age at RLS onset was 33.7 +/- 19.5 years. Overtly pathological tremor was rare, but trace tremor was very common. Overall, we found a very high rate of undiagnosed RLS in patients presenting for tremor, but unlike other "secondary" forms of RLS, this finding was also associated with a high familial history of RLS, suggesting that they share some genetic similarities.

Adolescent↗
PubMed1990

Uniform frequency of parkinsonian resting tremor in the lips, jaw, tongue, and index finger.

Parkinsonian resting tremor was examined in the lips, jaw, tongue, and index finger using electromyography (EMG) and displacement transduction. Long-term spectral averaging of tremor movement and EMG signals revealed that resting tremor frequencies were remarkably uniform across these orofacial and hand structures within the same parkinsonian subjects. However, marked variability in tremor spectral amplitude across structures and subtle moment-to-moment variations in tremor period, amplitude, and waveform shape were also observed. Although these observations argue for a central source of tremor, it appears that interactive central and/or peripheral neural circuitry may yield variations in tremor characteristics.

Aged↗
PubMed1993

MR imaging findings of tremors associated with lesions in cerebellar outflow tracts: report of two cases.

Two cases with severe tremors were studied by means of electromyograms using surface electrodes and also by magnetic resonance (MR) imaging. The first case was associated with multiple sclerosis and demonstrated a severe postural cerebellar tremor and an alternate activation of antagonist muscles in the right arm. The second case, with hemorrhage in the brainstem, demonstrated a severe tremor at rest and mixed synchronous and alternating activation of antagonist muscles in the left forearm. MR imaging studies localized lesions possibly responsible for these tremors. In the first case a lesion was located in the superior cerebellar peduncle just under the decussation, and in the second case a lesion was found between the red nucleus and the thalamus, with possible involvement of both the cerebellothalamic and nigrostriatal pathways. The first case accords with the theory that a lesion located in the dentate nucleus and its projection can cause severe postural cerebellar tremor. The lesion demonstrated in the second case may be responsible for "cerebellar tremor at rest" or "static (resting) cerebellar tremor."

Adult↗
PubMed1994

Botulinum toxin A injections for the treatment of hand tremors.

We conducted an open-label study to determine the utility of treating severe hand tremors with intramuscular injections of botulinum toxin (BTX) in forearm and arm muscles in 26 patients, 12 with Parkinson's disease (PD) and 14 with essential tremor (ET). The effect after 6 weeks for each patient was evaluated using two clinical rating scales, subjective evaluations of functional improvement and global disability, measures of weakness, and computer-assisted quantitative assessments of tremor. Although none of the clinical scores averaged > 3/4 point change, statistical significance was found on comparison of pre- and postinjection scores in the Webster Tremor and Global Disability Scales in the ET patients. Similarly, although average tremor amplitudes decreased by no more than 25% by quantitative analysis, amplitude decrease significantly correlated with patient subjective assessment in ET. In only two of 12 PD (17%) and three of 14 ET patients (21%) were major quantitative changes in tremor amplitude (> 50% reduction) found after BTX injections. Nevertheless, 10 patients (38%; five PD and five ET) reported moderate to marked subjective improvement in functional benefit after BTX. These findings suggest that although there were no major changes in clinical ratings or objective measurements, BTX injections may subjectively improve tremor in some patients, particularly those with ET.

Aged↗
PubMed1997

Clinical expression of essential tremor: effects of gender and age.

Essential tremor (ET) is considered to be a monosymptomatic disorder consisting primarily of postural hand tremor. Nevertheless, clinical expression can vary based on the body region affected by tremor and the coexistence of other neurologic signs, such as tandem gait disturbance. We conducted a two-part study to test the hypothesis that variability in ET clinical expression is influenced by gender and age. In part 1, we examined a large ET clinical database (n = 450), comparing ratings of postural hand and head/voice tremor based on gender. Head/voice tremor was significantly more frequent and more severe among female ET patients; men had more severe postural hand tremor. In part 2, ET patients (n = 40) had significantly more missteps when tandem walking in comparison to age-matched controls. Poor tandem walk in ET cases was associated with more advanced age, but not gender, disease duration, or ratings of postural hand or head/voice tremor. We conclude that gender influences the body region most affected by ET possibly through the effects of the sex chromosomes or hormones. Ataxia (tandem gait difficulty) is common in ET and may be an accentuation of cerebellar dysfunction due to aging.

Age Distribution↗