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Deuschl G, Becktepe JS, Dirkx M, Haubenberger D, Hassan A, Helmich R, Muthuraman M, Panyakaew P, Schwingenschuh P, Zeuner KE, Elble RJ. The clinical and electrophysiological investigation of tremor. Clin Neurophysiol 2022; 136:93-129. [DOI: 10.1016/j.clinph.2022.01.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 01/05/2022] [Accepted: 01/07/2022] [Indexed: 01/18/2023]
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Duval C, Daneault JF, Hutchison WD, Sadikot AF. A brain network model explaining tremor in Parkinson's disease. Neurobiol Dis 2016; 85:49-59. [DOI: 10.1016/j.nbd.2015.10.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 10/01/2015] [Accepted: 10/08/2015] [Indexed: 11/29/2022] Open
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Trenado C, Amtage F, Huethe F, Schulte-Mönting J, Mendez-Balbuena I, Baker SN, Baker M, Hepp-Reymond MC, Manjarrez E, Kristeva R. Suppression of enhanced physiological tremor via stochastic noise: initial observations. PLoS One 2014; 9:e112782. [PMID: 25397577 PMCID: PMC4232445 DOI: 10.1371/journal.pone.0112782] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 10/15/2014] [Indexed: 11/18/2022] Open
Abstract
Enhanced physiological tremor is a disabling condition that arises because of unstable interactions between central tremor generators and the biomechanics of the spinal stretch reflex. Previous work has shown that peripheral input may push the tremor-related spinal and cortical systems closer to anti-phase firing, potentially leading to a reduction in tremor through phase cancellation. The aim of the present study was to investigate whether peripherally applied mechanical stochastic noise can attenuate enhanced physiological tremor and improve motor performance. Eight subjects with enhanced physiological tremor performed a visuomotor task requiring the right index finger to compensate a static force generated by a manipulandum to which Gaussian noise (3–35 Hz) was applied. The finger position was displayed on-line on a monitor as a small white dot which the subjects had to maintain in the center of a larger green circle. Electromyogram (EMG) from the active hand muscles and finger position were recorded. Performance was measured by the mean absolute deviation of the white dot from the zero position. Tremor was identified by the acceleration in the frequency range 7–12 Hz. Two different conditions were compared: with and without superimposed noise at optimal amplitude (determined at the beginning of the experiment). The application of optimum noise reduced tremor (accelerometric amplitude and EMG activity) and improved the motor performance (reduced mean absolute deviation from zero). These data provide the first evidence of a significant reduction of enhanced physiological tremor in the human sensorimotor system due to application of external stochastic noise.
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Affiliation(s)
- Carlos Trenado
- Department of Neurology and Neurophysiology, University Freiburg, Freiburg, Germany
| | - Florian Amtage
- Department of Neurology and Neurophysiology, University Freiburg, Freiburg, Germany
| | - Frank Huethe
- Department of Neurology and Neurophysiology, University Freiburg, Freiburg, Germany
| | - Jürgen Schulte-Mönting
- Institute for Medical Biometry and Medical Informatics, University Freiburg, Freiburg, Germany
| | | | - Stuart N. Baker
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Mark Baker
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Elias Manjarrez
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México
- * E-mail: (RK); (EM)
| | - Rumyana Kristeva
- Department of Neurology and Neurophysiology, University Freiburg, Freiburg, Germany
- * E-mail: (RK); (EM)
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Mehta AR, Brittain JS, Brown P. The selective influence of rhythmic cortical versus cerebellar transcranial stimulation on human physiological tremor. J Neurosci 2014; 34:7501-8. [PMID: 24872555 PMCID: PMC4035515 DOI: 10.1523/jneurosci.0510-14.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/14/2014] [Accepted: 04/18/2014] [Indexed: 11/21/2022] Open
Abstract
The influence of central neuronal oscillators on human physiological tremor is controversial. To address this, transcranial alternating current stimulation (TACS) was delivered at peak tremor frequency to 12 healthy volunteers in a 2 × 2 crossover study. Two sites were stimulated [contralateral primary motor cortex (M1), vs ipsilateral cerebellum] while participants performed two types of tasks designed to probe the different manifestations of physiological tremor of the hand-kinetic and postural tremor. Tremor was measured by accelerometry. Cortical coherence with the accelerometry signal was also calculated in the absence of stimulation. The phase synchronization index, a measure of the phase entrainment of tremor, was calculated between stimulation and tremor waveforms. The amplitude modulation of tremor was similarly assessed. There was significant phase entrainment that was dependent both on tremor type and site of stimulation: M1 stimulation gave rise to phase entrainment of postural, but not kinetic, tremor, whereas cerebellar stimulation increased entrainment in both cases. There was no effect on tremor amplitude. Tremor accelerometry was shown to be coherent with the cortical EEG recorded during postural, but not kinetic, tremor. TACS modulates physiological tremor, and its effects are dependent both on tremor type and stimulation site. Accordingly, central oscillators play a significant role in two of the major manifestations of tremor in health.
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Affiliation(s)
- Arpan R Mehta
- Experimental Neurology Group, Division of Clinical Neurology, Nuffield Department of Clinical Neurosciences, Medical Sciences Division, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| | - John-Stuart Brittain
- Experimental Neurology Group, Division of Clinical Neurology, Nuffield Department of Clinical Neurosciences, Medical Sciences Division, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| | - Peter Brown
- Experimental Neurology Group, Division of Clinical Neurology, Nuffield Department of Clinical Neurosciences, Medical Sciences Division, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
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Daneault JF, Carignan B, Sadikot AF, Panisset M, Duval C. Drug-induced dyskinesia in Parkinson's disease. Should success in clinical management be a function of improvement of motor repertoire rather than amplitude of dyskinesia? BMC Med 2013; 11:76. [PMID: 23514355 PMCID: PMC3751666 DOI: 10.1186/1741-7015-11-76] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 03/20/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Dyskinesia, a major complication in the treatment of Parkinson's disease (PD), can require prolonged monitoring and complex medical management. DISCUSSION The current paper proposes a new way to view the management of dyskinesia in an integrated fashion. We suggest that dyskinesia be considered as a factor in a signal-to-noise ratio (SNR) equation where the signal is the voluntary movement and the noise is PD symptomatology, including dyskinesia. The goal of clinicians should be to ensure a high SNR in order to maintain or enhance the motor repertoire of patients. To understand why such an approach would be beneficial, we first review mechanisms of dyskinesia, as well as their impact on the quality of life of patients and on the health-care system. Theoretical and practical bases for the SNR approach are then discussed. SUMMARY Clinicians should not only consider the level of motor symptomatology when assessing the efficacy of their treatment strategy, but also breadth of the motor repertoire available to patients.
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Affiliation(s)
- Jean-François Daneault
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec H3A 2B4, Canada
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Bahgat D, Magill ST, Berk C, McCartney S, Burchiel KJ. Thalamotomy as a Treatment Option for Tremor after Ineffective Deep Brain Stimulation. Stereotact Funct Neurosurg 2013; 91:18-23. [DOI: 10.1159/000342491] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Accepted: 08/02/2012] [Indexed: 11/19/2022]
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Kuncel AM, Birdno MJ, Swan BD, Grill WM. Tremor reduction and modeled neural activity during cycling thalamic deep brain stimulation. Clin Neurophysiol 2011; 123:1044-52. [PMID: 21978653 DOI: 10.1016/j.clinph.2011.07.052] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 07/05/2011] [Accepted: 07/07/2011] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The effectiveness of deep brain stimulation (DBS) depends on both the frequency and the temporal pattern of stimulation. We quantified responses to cycling DBS with constant frequency to determine if there was a critical on and/or off time for alleviating tremor. METHODS We measured postural tremor in 10 subjects with thalamic DBS and quantified neuronal entropy in a network model of Vim thalamic DBS. We tested 12 combinations of cycling on/off times that maintained the same average frequency of 125 Hz, four constant frequency settings, and baseline. RESULTS Tremor and neural firing pattern entropy decreased as the percent on time increased from 50% to 100%. Cycling with stimulation on for at least 60% of the time was as effective as regular stimulation. All cycling settings reduced the firing pattern entropy of model neurons from the no stimulation condition by regularizing pathological firing patterns, either through synaptically-mediated inhibition or axon excitation. CONCLUSIONS These results indicate that pauses present in cycling stimulation decreased its effectiveness in suppressing tremor, and that changes in the amount of tremor suppression were strongly correlated with changes in the firing pattern entropy of model neurons. SIGNIFICANCE Cycling stimulation may reduce power consumption during clinical DBS, and thereby increase the battery life of the implanted pulse generator.
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Affiliation(s)
- Alexis M Kuncel
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, United States
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The organization of upper limb physiological tremor. Eur J Appl Physiol 2011; 112:1269-84. [DOI: 10.1007/s00421-011-2080-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 07/05/2011] [Indexed: 10/18/2022]
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Bethel-Brown CS, Morris JK, Stanford JA. Young and middle-aged rats exhibit isometric forelimb force control deficits in a model of early-stage Parkinson's disease. Behav Brain Res 2011; 225:97-103. [PMID: 21767573 DOI: 10.1016/j.bbr.2011.07.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 06/28/2011] [Accepted: 07/02/2011] [Indexed: 11/19/2022]
Abstract
Deficits in manual motor control often accompany the early stages of Parkinson's disease (PD), and are often revealed through isometric force tasks. In order to determine whether similar deficits occur in a rat model of early-stage PD, young (8 months) and middle-aged (18 months) rats were trained to produce sustained press-hold-release isometric forelimb responses that allowed for analyses of force output and spectral analysis of forelimb stability and tremor. Rats then received a 6-hydroxydopamine (6-OHDA) infusion into the striatum contralateral to the trained forelimb and were tested for 4 weeks post-lesion. The resulting partial striatal dopamine depletions (which at 41±12% and 43±6% in young and middle-aged rats, respectively, did not differ between the two groups) resulted in isometric forelimb deficits. Specifically, rats exhibited significantly diminished force stability and increased high frequency (10-25Hz) tremor, indicating potential postural disturbances and increased postural tremor, respectively. Durations of press-hold-release bouts were also increased post-lesion, suggesting difficulty in task disengagement. Despite pre-lesion differences in some of the force measures, the effects of partial nigrostriatal DA depletion did not differ between the two age groups. These results support the use of the press-while-licking task in preclinical studies modeling isometric force control deficits in PD.
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Affiliation(s)
- Crystal S Bethel-Brown
- Departments of Molecular & Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, United States
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Finger tremor can be voluntarily reduced during a tracking task. Brain Res 2011; 1370:164-74. [DOI: 10.1016/j.brainres.2010.11.047] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Revised: 11/10/2010] [Accepted: 11/10/2010] [Indexed: 11/23/2022]
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Daneault JF, Carignan B, Duval C. Bilateral effect of a unilateral voluntary modulation of physiological tremor. Clin Neurophysiol 2010; 121:734-43. [PMID: 20185364 DOI: 10.1016/j.clinph.2009.11.083] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 11/11/2009] [Accepted: 11/26/2009] [Indexed: 11/30/2022]
Affiliation(s)
- Jean-François Daneault
- Département de Kinanthropologie, Université du Québec à Montréal, Montréal, Que., Canada
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Chakravarty MM, Sadikot AF, Germann J, Hellier P, Bertrand G, Collins DL. Comparison of piece-wise linear, linear, and nonlinear atlas-to-patient warping techniques: analysis of the labeling of subcortical nuclei for functional neurosurgical applications. Hum Brain Mapp 2010; 30:3574-95. [PMID: 19387981 DOI: 10.1002/hbm.20780] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Digital atlases are commonly used in pre-operative planning in functional neurosurgical procedures performed to minimize the symptoms of Parkinson's disease. These atlases can be customized to fit an individual patient's anatomy through atlas-to-patient warping procedures. Once fitted to pre-operative magnetic resonance imaging (MRI) data, the customized atlas can be used to plan and navigate surgical procedures. Linear, piece-wise linear and nonlinear registration methods have been used to customize different digital atlases with varying accuracies. Our goal was to evaluate eight different registration methods for atlas-to-patient customization of a new digital atlas of the basal ganglia and thalamus to demonstrate the value of nonlinear registration for automated atlas-based subcortical target identification in functional neurosurgery. In this work, we evaluate the accuracy of two automated linear techniques, two piece-wise linear techniques (requiring the identification of manually placed anatomical landmarks), and four different automated nonlinear atlas-to-patient warping techniques (where two of the four nonlinear techniques are variants of the ANIMAL algorithm). Since a gold standard of the subcortical anatomy is not available, manual segmentations of the striatum, globus pallidus, and thalamus are used to derive a silver standard for evaluation. Four different metrics, including the kappa statistic, the mean distance between the surfaces, the maximum distance between surfaces, and the total structure volume are used to compare the warping techniques. The results show that nonlinear techniques perform statistically better than linear and piece-wise linear techniques. In addition, the results demonstrate statistically significant differences between the nonlinear techniques, with the ANIMAL algorithm yielding better results.
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Affiliation(s)
- M Mallar Chakravarty
- McConnell Brain Imaging Center, Montréal Neurological Institute, McGill University, Quebec, Canada.
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Carignan B, Daneault JF, Duval C. Quantifying the importance of high frequency components on the amplitude of physiological tremor. Exp Brain Res 2009; 202:299-306. [DOI: 10.1007/s00221-009-2132-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Accepted: 12/08/2009] [Indexed: 10/20/2022]
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Carignan B, Daneault JF, Duval C. The amplitude of physiological tremor can be voluntarily modulated. Exp Brain Res 2009; 194:309-16. [PMID: 19169676 DOI: 10.1007/s00221-008-1694-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Accepted: 12/12/2008] [Indexed: 11/26/2022]
Affiliation(s)
- Benoit Carignan
- Département de Kinanthropologie, Université du Québec à Montréal, 1205, rue St-Denis, Montreal, QC, Canada
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Morrison S, Kerr G, Silburn P. Bilateral tremor relations in Parkinson's disease: effects of mechanical coupling and medication. Parkinsonism Relat Disord 2007; 14:298-308. [PMID: 17977054 DOI: 10.1016/j.parkreldis.2007.09.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Revised: 09/10/2007] [Accepted: 09/20/2007] [Indexed: 10/22/2022]
Abstract
The aim of the present study was to examine the dynamics of bilateral multiple segment resting and postural tremor in 12 young, older subjects and eight Parkinson's (PD) patients in their different medication states. A second aim was to investigate whether bilateral independence of upper limb tremor was preserved for PD patients with amplified tremor under conditions where no upper limb segment was supported. Under these conditions, the likelihood for mechanical transmission between segments was increased. Tremor was recorded, bilaterally, from the hand and finger segments of all subjects. In addition to the PD subjects exhibiting greater tremor under both on/off medication states than the young/old control subjects, the tremor increase within limb from the hand to the finger was 2-3 times greater for the PD group in comparison to the healthy subjects. Despite this increased tremor, no differences were observed in the level of coupling between limbs across groups. Furthermore, the degree of coupling between limbs for the PD group was unaffected by their medication state. Overall, these results demonstrate that bilateral independence of tremor in PD participants is preserved despite conditions which maximised the chance of increased coupling.
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Affiliation(s)
- S Morrison
- School of Physical Therapy, Old Dominion University, Norfolk, VA 23529, USA.
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Gour J, Edwards R, Lemieux S, Ghassemi M, Jog M, Duval C. Movement patterns of peak-dose levodopa-induced dyskinesias in patients with Parkinson's disease. Brain Res Bull 2007; 74:66-74. [PMID: 17683791 DOI: 10.1016/j.brainresbull.2007.05.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 04/10/2007] [Accepted: 05/09/2007] [Indexed: 11/17/2022]
Abstract
The present study characterized involuntary movements associated with levodopa-induced dyskinesias (LID) in patients with Parkinson's disease. We used amplitude, proportional energy, frequency dispersion and sample entropy to determine whether LID movement patterns are truly random, as clinical description seems to suggest, or possess some underlying pattern that is not visible to the naked eye. LID was captured using a magnetic tracker system, which provided 3D rendering of whole-body LID. Patients were instructed to maintain a standing position, with arms extended in front of them. We compared the measurements of the dyskinetic PD group (DPD) with 10 patients without dyskinesias (NDPD) and 10 control subjects. In comparison to the other two groups, movement patterns from the DPD group had significantly higher amplitude, confirming the presence of dyskinesias. In addition, higher frequency components in the power spectrum of velocity were detected, suggestive of higher velocity in LID movement. Furthermore, there was a concentration in narrow frequency bands, which suggested stable oscillatory activity. Finally, sample entropy revealed more regularity in the DPD group. Although not statistically significant, we found that the amplitude from the NDPD group had a tendency to be smaller than those of controls. As well, the spectra were often more dispersed for the NDPD group. In conclusion, the present results suggest that LID cannot be considered as purely random movement since they possess some deterministic pattern of motion. This may provide a way for patients to adapt to these involuntary movements while performing voluntary motor acts.
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Affiliation(s)
- Jackie Gour
- Department of Mathematics and Statistics, University of Victoria, PO Box 3045 STN CSC, Victoria, BC, Canada V8W 3P4
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Abstract
BACKGROUND It has been suggested that patients with migraine are at a higher risk of developing essential tremor (ET). In addition, it was shown that patients with migraine are at higher risk of subclinical vascular infarcts in the cerebellum, a structure believed to be implicated in ET. OBJECTIVE Determine whether patients with migraine who do not show clinically detectable ET have subtle alteration in their physiological tremor characteristics that may serve as a predictor for the eventual appearance of ET. METHODS The physiological tremor of 30 patients with migraine (25 women, mean age: 41 +/- 8 years) was examined using a laser displacement sensor. Tremor was recorded in 5 conditions: hand-rest, hand-postural, finger-rest, finger-postural, and finger-loading (70 g). We also recorded tremor in healthy controls who never experienced migraine. Amplitude, median power frequency, power dispersion (width of a frequency band containing 68% of the power), and power distribution within 3 predetermined frequency bands of interest (3.5 to 7.5, 7.5 to 12.5, and 16 to 30 Hz) were assessed in each condition. RESULTS All tremor characteristics described above were very similar between the migraine group and controls. These results were supported by the lack of correlation between tremor characteristics and the number of years of experiencing migraine (ranging from 3 to 41 years; mean: 20 +/- 10). Patients with aura (N = 21) had tremor characteristics similar to that of patients without aura (N = 9) and controls. CONCLUSION These results suggest that, if a link exists between migraine and ET, the latter might be the result of an "acute event" (eg, stroke) rather than a progressive alteration of tremorogenic mechanisms.
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Affiliation(s)
- Christian Duval
- Département de Kianthropologie, Université du Québec in Montréal, Canada
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Duval C, Panisset M, Strafella AP, Sadikot AF. The impact of ventrolateral thalamotomy on tremor and voluntary motor behavior in patients with Parkinson’s disease. Exp Brain Res 2005; 170:160-71. [PMID: 16328283 DOI: 10.1007/s00221-005-0198-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Accepted: 08/13/2005] [Indexed: 10/25/2022]
Abstract
A preferred target for parkinsonian tremor alleviation is the ventrolateral (VL) thalamus. The goal of the present study is to determine how lesions involving the presumed cerebellar and pallidal recipient areas of the "motor" thalamus would alter the tremor and motor behavior of ten patients with Parkinson's disease (PD). Tremor amplitude, power dispersion (a measure of sharpness of the power spectrum of tremor), and power distribution were quantified using a laser displacement sensor prior to, and a week after, VL thalamotomy. As well, the impact of surgery on tremor seen during movement was quantified in a manual-tracking (MT) task. Tremor-induced noise (a measure of the amount of tremor present during movement) and ERROR (difference between subject's performance and target) were quantified. Finally, bradykinesia was assessed with a rapid alternating movement (RAM) task. Duration, range, and amplitude irregularity of wrist pronation-supination cycles were computed. Both motor tasks were quantified using a highly sensitive forearm rotational sensor. Healthy age-matched control subjects were also tested. Magnetic resonance images with an integrated atlas of thalamic nuclei were used to confirm lesion location. Results show that the lesions were centered upon the posterior portion of the ventral lateral (VLp) nucleus of the thalamus, included the posterior part of the ventral lateral anterior nucleus (VLa), and extended posteriorly to encroach upon the most rostral sector of the sensory ventral posterior nucleus (VPLa). VL thalamotomy significantly decreased tremor amplitude in all cases. Power dispersion was increased significantly so that it became similar to that of control subjects. Changes in power distribution indicate that thalamotomy selectively targeted PD tremor oscillations. Tremor detected during the MT task was also markedly decreased, becoming similar to that of controls. Patients also showed significant decrease in ERROR during MT. RAM duration and range were not significantly modified by the surgery, and patients' performance remained impaired compared to healthy control subjects. Collectively, these results suggest that lesions involving the presumed "cerebellar" and "pallidal" recipient sectors of the motor thalamus do not worsen bradykinesia, suggesting that neural circuits other than the pallido-thalamo-cortical loop may be involved in slowness of movement in PD. A review of alternate pathways is presented.
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Affiliation(s)
- Christian Duval
- Faculty of Applied Health Science, Brock University, St. Catharines, Ontario, Canada
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