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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.

Adult↗

Primidone in essential tremor of the hands and head: a double blind controlled clinical study.

Uncontrolled clinical studies have suggested that primidone may be effective in reducing essential tremor thus providing a valuable alternative to beta-adrenoreceptor antagonists which are currently the drugs of first choice. A double blind, placebo controlled trial of primidone in essential tremor of the hands and head was carried out using both clinical and objective methods of assessment. Primidone was significantly superior to placebo in reducing the magnitude of hand tremor, its efficacy being comparable to that of propranolol. In two patients tremor was reduced to non-symptomatic levels, an effect rarely seen with propranolol. No consistent attenuation of head tremor was found. There was no correlation between serum primidone or derived phenobarbitone concentrations and the reduction of hand tremor. An acute toxic reaction to an initial small dose (62.5 mg) of primidone was seen in six of 22 patients.

Adolescent↗

Finger tremor in Parkinson's disease.

Finger tremor was investigated in 20 patients (age range 54-88 yr) diagnosed as suffering from idiopathic Parkinson's disease and six controls of a similar age and no known neurological abnormality. In nine of the patients tremor was not clinically obvious. When the tremor of these patients was recorded immediately after voluntary movement and subjected to instrumental analysis there were consistently observable differences from the controls. Such analysis may have diagnostic potential when there is clinical uncertainty. Surface EMG recordings were obtained from four patients. One patient had a large resting tremor with obvious reciprocating activity in flexors and extensors; in the others who had no symptomatic tremor there was reciprocating activity only after movement, and this died away in a few seconds as the induced tremor disappeared.

Aged↗

Stereotactic thalamotomy in the treatment of essential tremor of the upper extremity: reassessment including a blinded measure of outcome.

The effectiveness of high frequency stimulation of the thalamic nucleus ventralis intermedius (Vim-HFS) for treatment of tremor has been studied by blinded assessment. The effectiveness of thalamotomy for essential tremor of the upper extremity by use of a blinded measure of outcome is now reported. Thalamotomy was performed in 21 patients (three operated on bilaterally) with medically intractable, essential tremor. Assessments of function, handwriting/drawing, and tremor amplitude were done before and at 3 and 12 months after surgery. The handwriting/drawing score was rated by a neurologist blinded to patient identity, laterality, and operative status. By comparison with baseline, both the total functional score and the total score from blinded assessment of handwriting/drawing improved significantly at 3 and 12 months after surgery. The two scores were significantly correlated, suggesting that the blinded assessment is a good predictor of a total disability from tremor. Complications after unilateral thalamotomy included transient dysarthria, permanent perioral numbness, and permanent mild disequilibrium in one patient each. Permanent mild dysarthria occurred in two of three patients operated bilaterally. Thus a blinded assessment of outcome establishes that unilateral thalamotomy is an effective, safe procedure for the treatment of essential tremor.

Aged↗

Multicentre European study of thalamic stimulation in essential tremor: a six year follow up.

BACKGROUND: Thalamic stimulation is an efficient treatment for disabling essential tremor, as previously shown, but follow up has mostly been short term. OBJECTIVES: To see whether good results can be maintained in the longer term. METHODS: 37 patients with essential tremor had implantation of a thalamic stimulator, either unilaterally or bilaterally. The results at one year have been reported earlier. After six years, 19 patients were available for follow up. The main instrument for evaluation was the essential tremor rating scale. The patients were examined with pulse generators turned on and off. RESULTS: In the majority of patients, the very good results with stimulation seen at one year were maintained after a mean of 6.5 years. The reduction in tremor scores and improvement in activities of daily living were highly significant compared with baseline and with the stimulation turned off. There were few serious adverse events. Minor side effects related to stimulation were common. Few device related complications were observed and most could be resolved. CONCLUSIONS: Good reduction in tremor can be maintained for more than six years in the majority of these severely disabled patients. Thalamic stimulation can be recommended in essential tremor where there is insufficient response to drug treatment. Surgical procedures and follow up should be concentrated in relatively few centres, which will thereby acquire a high degree of expertise.

Activities of Daily Living↗

Differences in frequency of finger tremor in otherwise asymptomatic mercury workers.

Tremor was measured from the index finger during low force, position holding in 18 control subjects and 18 battery workers with low level exposure to mercury. All workers were asymptomatic on clinical neurological examination. No differences were found in average tremor amplitudes between the groups, but statistically significant abnormalities in tremor frequency distribution existed. Tremor power spectra in the group of mercury workers were shifted toward the higher frequencies and compressed into narrow frequency peaks. These results suggest that measurements of finger tremor that evaluate the frequency distribution can produce a higher diagnostic yield than traditional visual clinical judgement. The findings also confirm other reports that currently permitted exposures to mercury are associated with subtle but distinctive differences in tremor accompanying voluntary movement.

Adult↗

Neuronal activity in GP and Vim of parkinsonian patients and clinical changes of tremor through surgical interventions.

Microrecordings were performed during pallidotomy and thalamotomy for Parkinson's disease (PD). Neuronal activity in globus pallidus (GP) was in general agreement with previous studies of human and primate models of PD. Neuronal activity, where frequency of tremor appeared to oscillate independently from peripheral input, was encountered in GPi. In contrast, neuronal activity in Vim regarding frequency of firing also correlated with tremor and was passively driven by kinesthetic stimuli with a somatotopic arrangement. Pallidal lesions based on microrecording induced relative reductions of tremor, while small Vim lesions immediately alleviated tremor. Basal ganglia pathology due to dopamine depletion could generate oscillatory neuronal activity in GPi, which may cause tremor. However, peripheral feedback to the motor cortex via Vim is also significant for tremorgenesis, because Vim may be an excitatory driving source for motor cortical neurons. Thus, a Vim lesion could reduce excitability of the motor cortical neurons and abolish tremor.

Electromyography↗

Vocal tremor reduction with deep brain stimulation.

We present a case illustration of the significant effect that deep brain stimulation (DBS) of the thalamus can have on vocal tremor. A 72-year-old female with a history of essential tremor was noted preoperatively to have a moderate vocal tremor (3 on a scale of 1-5). Following bilateral DBS of the thalamus, the vocal tremor rating improved to 1. Acoustic analysis demonstrated her vocal tremor to be affecting the amplitude of her voice at 5.58 Hz preoperatively, at 1. 93 Hz postoperatively with both leads on and at 1.54 Hz with only the left lead on. A videotaped endoscopic view of the patient's vocal cords (presented at the 1999 ASSFN meeting) clearly illustrated the dramatic changes apparent in the vocal tremor when the stimulators were turned on and off.

Aged↗

Thalamic stimulation for disabling tremor in a patient with spinocerebellar degeneration.

Thalamic stimulation alleviated coarse action tremor in a patient with spinocerebellar degeneration (SCD) and led to substantial improvement in daily functioning, though disability from ataxia remained. Intraoperative microrecording revealed a significant correlation between neuronal activity of the ventral intermediate nucleus (Vim) and tremor electromyograms. The tremor-correlated activities of Vim neurons and abolition of the tremor by Vim stimulation suggest that Vim may be related to the generation of action tremor in SCD. Thalamic stimulation can be a useful treatment option for SCD patients with disabling tremor.

Aged↗

Two patients with tremor caused by cortical lesions.

Myoclonic tremor due to cortical lesions is a rare condition and must be distinguished from other causes of tremor. This is because the treatment strategies of tremor may differ due to the various etiologies. We present here two cases with myoclonic tremor caused by parietal cortical lesions showing tremulous finger movement provoked by action and posture. Clinical and electrophysiological features of the patients were reported and compared with the features of the patients with cortical tremor in association with cortical reflex myoclonus. Both of our patients responded well to anticonvulsants such as valproate and clonazepam. In patients with acute postural tremor, cortical lesions such as mass occupying lesions, ischemic lesions and arteriovenous malformations should be taken into consideration.

Adult↗

Stereotactic thalamotomy for medically intractable essential tremor.

Objective surgical symptomatic outcome of ventrolateral (VL) thalamotomy specifically for essential tremor is uncommonly reported and functional outcome has not been investigated previously. In the present series, 7 patients underwent unilateral and 1 patient staged bilateral VL thalamotomies for disabling medically refractory essential tremor. At follow-up examination (mean 17.3 months, range 1-50 months), all patients enjoyed complete ablation or significant amelioration of the targeted tremor. Disability as determined by a modified form of an established rating scale for tremor was reduced from moderate (57%) or severe (43%) to absent (86%) or mild (14%). Interestingly, voice tremor was ablated or significantly improved in 71.4% of patients with preoperative voice tremor.

Follow-Up Studies↗

'Atypical' tremor.

The tremor present in a small number of patients who present with features of both Parkinson's disease (PD) and essential tremor (ET) is ill-defined. We therefore studied 8 such patients with 'atypical' tremor and compared them clinically to 11 PD and 10 ET patients in a double-blind, cross-over, placebo-controlled trial. Tremor was assessed via accelerometry and surface EMG. Tremor frequency and the acute tremorlytic response to propranolol were not useful in discriminating between groups. Over 80% of atypical and PD patients showed alternating EMG, whereas 90% of ET patients had synchronous EMG activity. Tremor amplitude improved by > 90% in 38% of atypical, 27% of PD and none of the ET patients after single-dose L-dopa/benserazide (300/75 mg), a response which was significantly different between the ET and PD groups. Failure to differentiate electrophysiologically and pharmacologically between the atypical and other groups probably relates to clinical heterogeneity in the atypical group.

Benserazide↗

Botulinum toxin A in non-dystonic tremors.

The present pilot study evaluated the effect of botulinum toxin A on primarily non-dystonic tremors using accelerometry in a single-blind, placebo-controlled design. Resting, postural, intention, or head tremor were assessed before and approximately 1 month after intramuscular saline and botulinum toxin A (25-50 U) respectively. Half of the patients showed > or = 30% placebo effect. Tremor in 10 of 17 patients (60%) studied improved further after botulinum toxin A (range 30-95%), exceeding the placebo effect by > or = 30%. Nine patients demonstrated clinically significant focal weakness in the extensor muscles after botulinum toxin A which interfered with fine movements. Patients were subdivided into PD-like and ET-like tremor(s). Both groups experienced large placebo effects for resting tremor, with little or no further improvement after botulinum toxin A. The improvement in postural tremor after botulinum toxin A, of 40% in the PD-like and 57% in the ET-like groups, however, was approximately twice that of placebo. In conclusion, botulinum toxin A exerts a modest tremorlytic effect, however the dose, and its distribution over the sites injected, need to be optimised to minimise focal weakness.

Adult↗

Stereotactic selective thalamotomy for the treatment of tremor type cerebral palsy in adolescence.

6 cases with tremor-athetotic type cerebral palsy and 2 cases with moderate dystonia-tremor type cerebral palsy were treated by selective stereotactic thalamotomy. In the former group, postural-movement type tremor in the upper limb gradually progressed with age while athetosis remained unchanged. In the latter group, dystonia in the truncal muscles predominated over the irregular tremulous movement of the upper limbs. In all cases, the intelligence was almost normal. Stereotactic selective thalamotomy (Vim for tremor athetosis, VL-Vim for dystonia tremor) was performed under local anesthesia with the aid of radiological and neurophysiological control methods. The results of the operations were satisfactory in regard to the tremor relief and concomitant improvement of motor performances in most of the cases. Stereotactic treatment might be an effective way to make possible a one-step progress in these handicapped cases. The importance of postoperative physical therapy is also emphasized.

Adolescent↗

Comparison of tremor responses to orally administered albuterol and terbutaline.

This study was designed to compare the initial tremor response to 4.0 mg albuterol and 5.0 mg terbutaline orally administered and to study the question of tachyphylaxis by rechallenge after 3 wk of maintenance dosing. Twenty fasting patients with severe COPD in whom orally administered sympathomimetics were withheld for 2 wk were challenged with single doses of each drug in a crossover, randomized fashion 1 wk apart. Then after a further 3 wk of dosing 3 times a day of the second medication (10 patients received each medication), they were challenged once more 16 h after the last dose. Rest and postural tremor were measured at zero and 2 h using an accelerometer affixed to the finger, and measurements of subjective tremor, tremor power spectrum, plasma cyclic AMP and lactate, and forced vital capacity were also made. Postural tremor increased from 25.05 to 36.20 relative units for albuterol, an increase of 11.15 units, and from 24.90 to 57.70 units for terbutaline, an increase of 32.80 units (difference significant at p = 0.01). Plasma cyclic AMP (p less than 0.01) and lactate (p = 0.05) increases were also less for albuterol, and the FEV1 and FVC responses, though about one third less, did not differ significantly. After 3 wk, mean baseline tremor for both drugs was elevated even 16 h after the last 3 times a day dosing (38.00 and 33.10) for albuterol and terbutaline (difference, NS), and responses were much less to the single tablet (3.40 and 9.10, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

Frontal functions in young patients with essential tremor: a case comparison study.

Essential tremor (ET) is classified as a pure motor system disease. It has been previously reported that impairments in cognitive functions can be associated with ET. The authors assessed cognitive functions in a relatively young patient group with ET and comparison subjects. Correlations between tremor severity and regional cerebral blood flow (rCBF) and neuropsychological test performances of ET patients and comparison subjects were investigated. Sixteen patients with ET and 16 comparison subjects were assessed by a comprehensive neuropsychological test battery designed to assess global attention, language, memory, visuospatial functions, and executive functions. In 11 of 16 patients and in nine of 16 comparison subjects, rCBF was measured by technetium-99m-hexamethyl propylene amine oxime single photon emission computed tomography (technetium-99m-HMPAO SPECT). The tremor severity was quantified using the Clinical Rating Scale for Tremor (CRST). Findings revealed that ET patients differed significantly from comparison subjects on tests assessing visuospatial functions and verbal memory, whereas differences in other tests did not reach statistical significance. There was no significant difference between the rCBF of ET patients and comparison subjects. There were statistically significant inverse correlations between tremor severity and executive functions. Tremor severity was inversely correlated with bilateral frontal blood flow by technetium-99m-HMPAO SPECT. Conclusions suggest that the subclinical cognitive deficits characterized by visuospatial and verbal memory impairments and executive dysfunction may be a clinical feature of ET, and the cerebello-thalamo-frontal network may play a role in the pathophysiology of this disorder.

Adolescent↗

The influence of tonic muscle activation on human jaw displacement tremor.

Jaw displacement tremor was investigated. Both tremor amplitude and tremor frequency were found to increase with increasing muscle activation. Co-contraction of jaw elevator and jaw depressor muscles was employed in order to vary muscle activation levels without the teeth being in occlusion. Reproducibility of tremor changes was statistically significant for each individual investigated. The relationship between tremor frequency and tremor amplitude, over the range of muscle activation investigated, varied per individual. It is hypothesized that the physiological basis for this inter-individual variation is differences in the development of jaw stiffness with increasing muscle activation between subjects. This explanation may be the basis, at least in part, for the clinical presence of objective jaw stiffness in one subject and its absence in another.

Humans↗

An evaluation of laryngeal muscle activation in patients with voice tremor.

Eight patients with voice tremor were studied to characterize laryngeal muscle involvement. Electromyographic (EMG) recordings were made from intrinsic laryngeal muscles, simultaneously with some extrinsic laryngeal muscles, respiratory movement, and voice recordings during respiration, whisper, and phonation. Spectral measures were used to determine the tremor frequency and the prominence of spectral peaks in the EMG, respiratory and acoustic signals, while correlation coefficients were computed between pairs of tremulous EMG signals to measure the synchrony of tremor between muscles. The intrinsic laryngeal muscles were tremulous during respiration and speech, with the thyroarytenoid most often involved. Tremor was also detected in some of the extrinsic muscle recordings and the percentage of muscles with tremor was higher during phonation than during whisper or respiration. Time delays were found between tremor oscillations in laryngeal muscles. Because the thyroarytenoid was affected in all the patients studied, botulinum toxin injections may be beneficial in treatment of this voice disorder.

Aged↗