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PubMed1992

The symptomatic and functional outcome of stereotactic thalamotomy for medically intractable essential tremor.

Eight patients with medically refractory disabling essential tremor underwent ventralis lateralis (VL) thalamotomies; the procedure was unilateral in seven cases and bilateral (staged) in the other. Contralateral tremor remained absent or markedly reduced in all patients at the time of the most recent follow-up examinations, at a mean of 17.3 months after surgery. Disability was determined by a modified form of an established rating scale for tremor, and was reduced from a mean score of 21.1 (moderate grade) to 3.9 (absent grade) (p less than 0.001). Interestingly, voice tremor was abolished or significantly improved in 71.4% of patients with preoperative voice tremor. This feature has not been reported previously. Persistent surgical morbidity was limited to two patients with mild dysarthria and one with a mild cognitive impairment. There were no surgically related deaths. It is concluded that stereotactic VL thalamotomy is a treatment option for medically intractable disabling essential tremor.

Adolescent↗
PubMed1992

Symptomatic and functional outcome of stereotactic ventralis lateralis thalamotomy for intention tremor.

In the past, intention tremor has responded well to selected neuroablative procedures; however, objective symptomatic and functional outcomes of ventralis lateralis (VL) thalamotomy specifically for intention tremor in the post-computerized tomography era has rarely been reported. This series explored the symptomatic and functional impact of VL thalamotomy on 14 patients presenting at the Mayo Clinic with severe, refractory intention tremor due to multiple sclerosis (five patients), trauma (four patients), or stroke (five patients). General neurological examinations, psychometric evaluations, speech pathology assessments, and neuroradiological scans were performed. Pre- and postoperative disability were graded according to a modified form of an established rating scale for tremor. All patients received VL radiofrequency thalamotomies utilizing neurophysiological recording and stimulation control. Contralateral targeted upper-extremity tremor remained symptomatically absent or markedly reduced in 81.8% of cases (mean follow-up period 23.4 months). The median disability score was reduced by 12 points (0.02 less than p less than 0.05). Persistent surgical morbidity was limited to two patients with mild, nondisabling dysarthrias. One elderly patient died of pulmonary complications 2 weeks postoperatively. There were no reported surgically induced exacerbations in multiple sclerosis; however, some of these patients exhibited difficulties with electrophysiological localization. These results compare favorably with those reported in the literature and confirm that stereotactic VL thalamotomy for debilitating intention tremor carries a low surgical risk and can be an effective treatment option for properly selected patients.

Adolescent↗
PubMed2000

Long-term deep brain stimulation in a patient with essential tremor: clinical response and postmortem correlation with stimulator termination sites in ventral thalamus. Case report.

Essential tremor can be suppressed with chronic, bilateral deep brain stimulation (DBS) of the ventralis intermedius nucleus (Vim), the cerebellar receiving area of the motor thalamus. The goal in this study was to correlate the location of the electrodes with the clinical efficacy of DBS in a patient with essential tremor. The authors report on a woman with essential tremor in whom chronic bilateral DBS directed to the ventral thalamus produced adequate tremor suppression until her death from unrelated causes 16 months after placement of the electrodes. Neuropathological postmortem studies of the brain in this patient demonstrated that both stimulators terminated in the Vim region of the thalamus, and that chronic DBS elicited minor reactive changes confined to the immediate vicinity of the electrode tracks. Although the authors could not identify neuropathological abnormalities specific to essential tremor, they believe that suppression of essential tremor by chronic DBS correlates with bilateral termination of the stimulators in the Vim region of the thalamus.

Brain Mapping↗
PubMed1980

Physiologic and pathologic tremors. Diagnosis, mechanism, and management.

Tremor, the commonest of the involuntary movement disorders, is characterized by rhythmical oscillatory movement that occurs at rest or during activity; all tremors cease during sleep. Physiologic tremor is present in normal persons and is asymptomatic. Tremor is considered pathologic when it impairs a patient's function. Clinically, the pathologic tremors may be classified as accentuated physiologic, parkinsonian, essential, and cerebellar. We review here the basic mechanisms and clinical features of various tremors and emphasize recent advances in pathophysiology and management.

Alcoholic Beverages↗
PubMedDate not supplied

Effects of proximal and distal muscles' groups contraction and mental stress on the amplitude and frequency of physiological finger tremor. An accelerometric study.

Physiological finger tremor was assessed by two-dimensional solid accelerometry in 40 healthy normal subjects at rest (R) with the hand hanging over the armrest of a chair, in posture (P) with the arm rested on the armrest but the hand extended from the wrist, and finally adding proximal muscles contraction in extension (E) with the arm extended in front of the patient, each time with and without mental stress. The mean amplitude for physiological tremor, about 30 microns, was almost doubled by hand extension and increased by 4 to 5-fold by arm extension with further increase by mental stress in each position, which gives a good estimation of the contribution of proximal and distal muscles into the amplitude of physiological tremor. There was no significant effect of age between 20 and 60 years on tremor amplitude, but mean tremor frequency decreased significantly between 40 to 60 years. Mental stress increased amplitude but decreased tremor frequency of both across all position, possibly by increasing the synchronization of motor unit firing and by modifying the gain of the motoneurones and the stretch reflex as shown by electrophysiological studies.

Adult↗
PubMed2000

Dopamine deficiency in rubral tremor caused by midbrain hemangioma: case report.

To elucidate the nigrostriatal involvement in rubral tremor, we studied single photon emission computed tomography (SPECT) imaging with [2-[[2-[[[3-(4-chlorophenyl)-8-methyl-8-azabicyclo[3.2.1]oct-2- yl]methyl](2-mercaptoethyl)amino]ethyl]amino]ethanethiolato(3-)- N2,N2',S2,S2']oxo-[1R-(exo-exo)]-[99mTc]technetium ([99mTc]TRODAT-1) in a 70-year-old woman with a midbrain hemangioma. She had developed a slow tremor in her right arm and leg after an episode of hemorrhage at the age of 28. The tremor was 3 to 5 Hz in frequency at rest, which was enhanced by outstretching the limb and action. There was no rigidity or bradykinesia. Neurological examination also revealed mild palsy of the left oculomotor nerve. The magnetic resonance imaging (MRI) of the brain showed a small hemangioma in the left midbrain localized mainly in the substantia nigra. The [99mTc]TRODAT-1 SPECT imaging revealed significantly reduced [99mTc]TRODAT-1 uptake in the left caudate and putamen, but it was only mildly reduced in the right striatum. This reduction in uptake was even more severe than that of patients with Parkinson's disease, and indicated that the dopamine function was markedly impaired in the left nigrostriatal system. The tremor had not progressed over the years, and she responded moderately to treatment with levodopa. We concluded that the rubral tremor in the right extremities was probably caused by a dopamine deficiency in the left nigrostriatal system. This suggests that a dopamine deficiency secondary to the midbrain hemangioma might have contributed to the development of the rubral tremor in this patient.

Aged↗
PubMedDate not supplied

[Stereotactic thalamotomy for Parkinsonian and others types of tremor. Experiences of thalamic multiunit burst activity by means of semimicroelectrode].

INTRODUCTION: Better understanding of the basic mechanism of disorders of movement, together with improvements in surgery and electrophysiological techniques have led to a resurge of interest in the surgical treatment of patients with tremor. Ventrolateral thalamotomy has been considered to be an alternative neurosurgical treatment for disabled persons including those with drug-resistant Parkinson s disease and other types of tremor. PATIENTS AND METHODS: Thirty four of 47 patients had Parkinson s disease (n= 23), essential tremor (n= 4), multiple sclerosis (n= 5), olivopontocerebellar lesion (n= 1) and posttraumatic tremor (n= 1) and did not show satisfactory improvement after drug treatment. The lesions were made in the thalamic nucleus. In 26 patients simultaneous recordings were made of nerve activity in the thalamus and of burst activity. RESULTS: In 23% of the cases the appropriate site for the final lesion could not be determined in accordance with electrostimulation of the empirical objective. In these patients the objective was determined after observation of the electrophysiological activity localized to the burst activity seen during the operation. The patients were followed-up for 6-24 months (average 12 months); 88% of them had no tremor or moderate contralateral tremor. The patients were assessed on a modified Fahn scale. Average scoring fell from a preoperative evaluation of 73.8 points to 34.0 after three months; 30.7 after six months, 32.0 after 9 months, 37.1 after 12 months and 35.2 points after 18 months. CONCLUSION: Of 47 thalamotomies done, 13 (29%) were successful and 5 (10%) maintained their original state, but no cases became worse or had serious complications.

Corpus Striatum↗
PubMedDate not supplied

Paradoxical phenomenon of physiological tremor in prolonged tapping load.

Cumulative fatigue caused by a tapping load is investigated by power spectrum analysis of both physiological tremor of the finger and surface electromyogram (EMG) of the forearm muscle controlling the finger. A load for two hours at a rate of 200 taps/minute is performed on ten male subjects. The physiological tremor and the EMG are measured before and during the load. The measurement is performed under the isometric contraction at 10% maximum voluntary contraction in the m. flexor digitorum superficialis. The total power and the slow wave ratio of the power spectrum are evaluated. During the load, both spectra of the physiological tremor and the EMG show the maximum total power at 30 minutes after the load. The total powers of both spectra, however, decrease in the period after 60 minutes. Namely, the results of the physiological tremor and the EMG for prolonged load show the "paradox of fatigue." In order to elucidate the cause of the paradox of fatigue, the slow wave ratio of the EMG spectrum is studied. The ratio increases during the load. The muscle loaded indicates the state close to exhaustion, and the change of the function of the muscle contraction affects the amplitude of the physiological tremor. Therefore, the criterion judging muscular fatigue is denoted due to the change of the amplitude of the physiological tremor.

Adult↗
PubMed1975

Validity of quantitative tests measuring tremor.

A set of tests measuring tremor with an accelerometer has been developed to assist in objectively evaluating clinical trails. An experiment was designed to examine the consensual validity of the test measures for Resting, Sustention and Static Intention Tremor for 10 multiple sclerosis patients and 10 parkinsonian patients. Motion pictures of the patients performing the tremor tests were viewed by a senior neurologist who rated tremor using a nine-point ordinal scale. Comparisons made between the quantitative measures of tremor and the neurologist's ratings of tremor show that the tests are consensually valid. The methodology of this experiment may prove useful for examining in the future the consensual validity of new clinical instruments useful for evaluating trails.

Age Factors↗
PubMedDate not supplied

[Thalamic neuro inhibition in the treatment of post traumatic tremor].

INTRODUCTION: Severe head trauma could be followed by a wide range of movement disorders. Usually, they appear as a moderate or severe intention tremor that causes great patient disability. Those movement disorders use to be refractary to medical treatment, although sometimes they would be spontaneusly controlled by a year. CLINICAL CASE: 14 year old boy who suffered severe head trauma at age of 8. One year after the injury he developed an action tremor and choreiform dyskinesia with hemibalistic features evocated by the movement. Medical treatment was ineffective. Due to the great patients disability, we chose the surgical treatment based on the placement of an stimulation electrode in thalamic Vop/Vim complex, obtaining a tremor abolition with an improvement in the scales of tremor and quality of life. DISCUSSION: Surgical treatment of postraumatic tremors tryes to improve in terms of function and activities of daily living, more than suppresion of a symptom. The aim of this treatment is cut the palidal thalamic cortical pathways. Anyway, target is defined by the tremor related cells and, it is more a functional target than an anatomical one. We prefer stimulation more than lesion, due to the lack of brain definitive injury because its reversibility and adjustability features.

Adolescent↗
PubMed2003

[Neuroelectrophysiological basis and surgical treatment of essential tremor].

OBJECTIVE: To investigate the relationship between limb tremor and neuronal firing in thalamus (Vim) and retrospectively review the clinical effects and safety of the surgical treatment of essential tremor (ET). METHODS: Forty-two ET patients received microelectrode-guided thalamotomy and 11 cases were quantitatively evaluated with FAHN rating scales pre- and post-operatively. RESULTS: There were electrophysiological tremor-related neurons in ventrolateral part of thalamus. Lesioning of those neurons abolished contralateral limb tremor in all of the patients. No permanent contralateral weakness, dysarthria and hemorrhage were observed. CONCLUSION: "Tremor cell" in thalamus plays a key role in the symptom of ET patients. Destruction of those cells may completely and permanently abolish tremor symptom.

Adult↗
PubMed1992

[Novel possibilities for treatment of parkinsonian tremor and other abnormal movements by stimulation of the nucleus ventralis intermedius thalami].

Chronic thalamic stereotactic stimulation has been performed in 22 patients with disabling tremor and poor response to drug therapy: 17 parkinsonian tremors and 5 essential tremors. Our first results are presented with a mean follow-up of 26 months. Parkinsonian tremors 17 = complete disappearance: 12, clear improvement: 5. Essential tremors 5 = complete disappearance: 3, clear improvement: 1, failure 1 cured by thalamotomy. Choreic or ballistic dyskinesias 7 = complete disappearance: 5, clear improvements: 2. Dystonic dyskinesias 3 = complete disappearance: 2, failure: 1. This new stereotactic procedure permits to control easily not only tremor but also L-Dopa induced dyskinesias: choreic or ballistic dyskinesias and biphasic dystonic dyskinesias. The place of this surgical treatment among the other therapeutic possibilities is discussed.

Electric Stimulation Therapy↗
PubMed1992

[The dependence of rapid voluntary contractions on the tremor phase in parkinsonism].

Parkinsonian patients sometimes have problems to produce really fast motor responses. Often, these are significantly delayed in comparison to those of normal controls. In patients with tremor-at-rest, this delay might be induced by some attraction of the movement execution to the tremor oscillator, according to a hypothesis of Hallet et al. (1977). This study now examined the phase relationship between the on-going tremor and the onset of fast voluntary contractions in Parkinson's disease (PD), quantitatively. Five patients with prominent tremor-at-rest performed rapid isometric index finger abductions under self paced (SP) and reaction time (RT) conditions, and force and surface EMG signals from the FDI muscle were analyzed. In both conditions the SP and the RT, data showed that the onset of the contraction mostly occurs during the descending phase of the tremor oscillation and, accordingly, the phasic EMG burst synchronously with the tremor bursts confirming the above mentioned hypothesis.

Aged↗
PubMedDate not supplied

[Stereotactic ventrolateral thalamotomy in the treatment of Holmes tremor].

BACKGROUND AND PURPOSE: The authors report the results of stereotactic surgery for severe posttraumatic tremor in 7 patients. MATERIAL AND METHODS: All patients were severely incapacitated in their daily living activities by mainly kinetic and postural components of Holmes tremor. The 7 patients underwent 8 stereotactic operations. The stereotactic target in all patients was the ventrolateral thalamus. Patients were evaluated using the Clinical Rating Scale For Tremor (CRST) before and up to 24 months after stereotactic thalamotomy. RESULTS: In the postoperative period there was marked amelioration in kinetic and postural components of Holmes tremor in contralateral upper and lower extremity. The mean presurgery value for contralateral upper extremity kinetic tremor (scores 5-6 CRST) dropped from 3.25 to mean postsurgery value of 0.5. There was also a marked functional improvement. It was reduced from a mean value of 71% of maximum disability according to CRST (scores 15-21, part C CRST, 0% independent, 100% total dependent) to 28.5% over 2-year follow-up. CONCLUSIONS: Ventrolateral thalamotomy alleviates effectively Holmes tremor and improves greatly performance of activities of daily living.

Activities of Daily Living↗
PubMed1975

Intentional tremor on a helium-oxygen chamber dive to 49.5 ATA.

Tremor is a well-recognized manifestation of the high pressure nervous syndrome (HPNS). As such, its measurement and analysis during deep hyperbaric exposures can be an important index of central nervous system integrity. During the U.S. Navy's experimental chamber dive to a depth equivalent to 1600 fsw (49.5 ATA), objective measures of intentional tremor were obtained at several depths. Six subjects were pressurized in 6 days to 49.5 ATA. After spending 7 days at this pressure, they were decompressed in 19 days to the surface. Measures of intentional tremor were obtained predive and at pressure levels of 13.1, 31.3, 49.5, 40.4, and 31.3 ATA using the Naval Medical Research Institute Mark 3 Mod 1 tremor device. Each subject's microtremor was measured while he produced a force of 50 grams and 500 grams against a finger force transducer. Unlike previous studies of HPNS tremor, special attention was given to amplitude rather than frequency analysis. All subjects displayed a marked increase in tremor that interfered with fine motor performance at depths greater than 1000 fsw. A statistically significant increase in signal frequency was also observed.

Calibration↗
PubMedDate not supplied

MDR1 gene polymorphism in allogeenic kidney transplant patients with tremor.

P-glycoprotein (P-gp), an ATP-dependent efflux pump, is a membrane protein encoded by MDR1 gene, which demonstrates functional polymorphism. It is present in endothelial cells of the blood-brain barrier. P-gp pays a role in transmembrane transport of various xenobiotics, thus limiting their accumulation in the central nervous system. Cyclosporine A which is used as an immunosuppressive drug in patients with allogenic kidney grafts is a substrate for P-gp. Cyclosporine A may cause neurotoxic adverse effects, among them tremor. It was assumed that polymorphism of MDR1 gene which is associated with change in P-gp activity plays a role in induction of tremor in some patients with allogenic kidney graft treated with cyclosporine A. A total of 118 unrelated postransplant kidney patients were enrolled into the study. The tremor group included 23 cases and 95 randomly selected posttransplant individuals with no signs of tremor served as controls. No statistically significant correlation between MDR1 gene polymorphism C3435T and tremor was found. The tremor group and the control group were characterized by similar distribution of MDR1 genotypes, i.e. 3435CC, 3435CT, 3435TT.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1979

Quantification of muscle tremor of Huntington's disease patients and their offspring in an early detection study.

Accelerometer measurements of muscle tremor yielded significant findings for both Huntington's disease (HD) patients and their genetically at risk offspring. Although affected individuals are usually characterized by gross involuntary muscle movements, alterations in minute muscle tremor were also found in our sample of ten HD patients. Irregularities in tremor patterns were intensified with increased time since onset of the disorder and in addition reflected the effects of drug therapy for those on medication. The use of accelerometer measurements of muscle tremor may therefore, prove to be useful in evaluating new medications for affected individuals. For high risk immediate family members currently there is no safe and reliable method to identify, prior to clinical onset, any among them who will develop HD. Aberrant muscle tremor patterns resembling that shown by HD patients were found in one-third of a sample of 15 genetically at risk offspring. In the event an effective method of treatment is developed, early recognition of HD gene carriers by accelerometer tremor measurement could result in control of the disorder prior to substantial neurological damage.

Adult↗
PubMed2005

Tremor in Parkinson's disease patients can be induced by uncontrolled activation and uninhibited synchronization of alpha2-motoneuron firing to which alpha1-motoneuron firing synchronizes.

With the surface electromyography (sEMG) and the single nerve-fibre action potential recording method a mechanism is measured how rhythmic muscle contraction and tremor in Parkinson's disease patients is generated. With sEMG it could be shown that the tremor started when alpha2-motor units (FR-type) spontaneously began to fire synchronizedly oscillatory. Two possibilities of alpha2-motor unit synchronization were observed. In one case one alpha2-motor unit started to fire oscillatory and other alpha2-motor units started to fire oscillatory in synchronization with the first alpha2-motor unit. In a second case several alpha2-motor units fired oscillatory, but not in a synchronized manner. With the synchronization of the oscillatory firing alpha2-motor units again synchronizedly oscillatory firing of several alpha2-motor units appeared. When later on, several additional alpha1-motor units (FF-type) started to fire and in synchrony with the synchronizedly oscillatory firing alpha2-motor units (FR-type), rhythmic muscle contraction and tremor were observed. Visible muscle contraction and tremor stopped, when the alpha1-motor units stopped firing, which could a.o. be achieved by the patient concentrating on the tremor. The single nerve-fibre action potential recording method showed that alpha1 and alpha2-motoneurons in the cauda equine nerve roots fired oscillatory, that they could synchronize their firing and that these oscillatory firing motoneurons could build up an external loop to the periphery in the way that gamma-motoneurons and muscle spindle afferents were included in the rhythmic coordinated firing But the synchronization of oscillatory firing was only transient and the building up of an external loop to the periphery only occurred in non-Parkinson patients upon strong repetitive reflex stimulation. It is therefore concluded that in patients with Parkinson's disease there is firstly a lack of inhibition, so that motoneurons can start to fire oscillatory upon nearly no stimulation and there is secondly lack of mutual inhibition between oscillatory firing motoneurons, so that oscillatory firing motoneurons can synchronize their firing to give rise to rhythmic muscle contraction and tremor.

Action Potentials↗