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Pierre Ketelaer - One of the best experts on this subject based on the ideXlab platform.
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Unsteady gaze fixation enhances the severity of MS Intention Tremor
Neurology, 2008Co-Authors: Peter Feys, Werner Helsen, Pierre Ketelaer, Bart Nuttin, Ann Lavrysen, Stephan P. Swinnen, Xiaoshun LiuAbstract:Background: Patients with arm Intention Tremor due to multiple sclerosis (MS) often manifest eye movement deficits, illustrating the role of infratentorial brain in both ocular and manual movement control. Our previous study showed that both the amplitude of Intention Tremor and eye fixational movements were greatly enhanced after coordinated eye-hand action toward stationary targets vs during hand movements with continuous target fixation. Objective: The present study tested, during coordinated step-tracking movements, the hypothesis that the amplitude of hand Intention Tremor was influenced by (unsteady) gaze fixation onto the target. Methods: Simultaneously recorded eye and hand tracking movements were compared between 13 MS patients with Intention Tremor and 14 healthy controls over conditions in which the magnitude of the primary eye and hand tracking movements, as well as their ratio, were altered. Results: Patients always made larger fixational eye movements around the visual targets than the controls. In the patient group, the size of fixational eye movements decreased following a reduction in the magnitude of the preceding saccadic movement, and most interestingly, was accompanied with a decrease in Tremor amplitude. An alteration in the magnitude of the primary hand movement did not affect the Tremor severity. Conclusions: In patients with multiple sclerosis with Intention Tremor, the unsteady gaze fixation on the visual targets is proportional to the magnitude of the preceding saccades, and influences the severity of Intention Tremor during eye-hand coordinated visuomotor tasks.
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The effect of changed visual feedback on Intention Tremor in multiple sclerosis.
Neuroscience letters, 2005Co-Authors: Peter Feys, Werner Helsen, Pierre Ketelaer, Bart Nuttin, Martinus J. Buekers, Tanja Ceux, Elke Heremans, Xuguang LiuAbstract:In patients with multiple sclerosis (MS), Intention Tremor amplitude is enhanced during the visually guided compared to the memory guided motor tasks. In the present study, the effect of visual feedback on Intention Tremor was investigated during visually guided wrist step-tracking tasks. Specifically, visual feedback of the hand was provided either instantly or averaged over different time windows. Thirteen MS patients with Intention Tremor and 14 healthy controls performed the wrist step-tracking task, while the visual representation of the actual hand position was displayed instantly or averaged over time windows of 150, 250 and 350 ms. It has been found in the patient group that, in association with a decreased initial error and decreased Tremor amplitude on the screen, the amplitude of the actual performed Tremor also decreased when visual feedback was changed. The Tremor reduction was not different between conditions with manipulated feedback, although delays in presenting visual feedback of the hand position increased when the time window was larger. The reduction in overall Tremor amplitude was unlikely related to other factors, such as eye fixation deficits or the speed of the primary hand movement. These results suggest that hand Tremor severity is dependent on the visual feedback of position and movement errors.
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Effects of peripheral cooling on Intention Tremor in multiple sclerosis
Journal of neurology neurosurgery and psychiatry, 2005Co-Authors: Peter Feys, Werner Helsen, Bart Nuttin, Xiaoshun Liu, D Mooren, H Albrecht, Pierre KetelaerAbstract:Objective: To investigate the effect of peripheral sustained cooling on Intention Tremor in patients with multiple sclerosis (MS). MS induced upper limb Intention Tremor affects many functional activities and is extremely difficult to treat. Materials/Methods: Deep (18°C) and moderate (25°C) cooling interventions were applied for 15 minutes to 23 and 11 Tremor arms of patients with MS, respectively. Deep and moderate cooling reduced skin temperature at the elbow by 13.5°C and 7°C, respectively. Evaluations of physiological variables, the finger tapping test, and a wrist step tracking task were performed before and up to 30 minutes after cooling. Results: The heart rate and the central body temperature remained unchanged throughout. Both cooling interventions reduced overall Tremor amplitude and frequency proportional to cooling intensity. Tremor reduction persisted during the 30 minute post cooling evaluation period. Nerve conduction velocity was decreased after deep cooling, but this does not fully explain the reduction in Tremor amplitude or the effects of moderate cooling. Cooling did not substantially hamper voluntary movement control required for accurate performance of the step tracking task. However, changes in the mechanical properties of muscles may have contributed to the Tremor amplitude reduction. Conclusions: Cooling induced Tremor reduction is probably caused by a combination of decreased nerve conduction velocity, changed muscle properties, and reduced muscle spindle activity. Tremor reduction is thought to relate to decreased long loop stretch reflexes, because muscle spindle discharge is temperature dependent. These findings are clinically important because applying peripheral cooling might enable patients to perform functional activities more efficiently.
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Interaction between eye and hand movements in multiple sclerosis patients with Intention Tremor
Movement disorders : official journal of the Movement Disorder Society, 2005Co-Authors: Peter Feys, Werner Helsen, Bart Nuttin, Ann Lavrysen, Stephan P. Swinnen, Xuguang Liu, Pierre KetelaerAbstract:Deficient eye and hand movements are present in patients with multiple sclerosis. In the present study, eye and hand movements were simultaneously measured during visually guided wrist step-tracking tasks in 16 patients with Intention Tremor and 15 healthy controls. The coupling between eye and hand movements was analyzed during simultaneous eye-hand tracking, and interactions were studied by comparing the coordinated eye-hand condition with isolated eye- or hand-tracking conditions. Despite movement abnormalities, the onset of eye and hand movements was highly correlated and an invariant coupling between the saccadic completion time and hand peak velocity was found, suggesting that the temporal coupling was very much preserved. The differences between the experimental tracking conditions suggest that, in MS patients with Intention Tremor, the ocular system influenced the hand movements. Intention Tremor amplitude was reduced when there was no preceding saccadic eye movement, whereas conversely, eye movements were not affected by different hand Tremor severity.
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Interference of upper limb Tremor on daily life activities in people with multiple sclerosis.
Occupational therapy in health care, 2004Co-Authors: Peter Feys, Anders Romberg, Juhnai Ruutiainen, Pierre KetelaerAbstract:SUMMARY The interference of upper limb Intention Tremor on activities of daily living was described in 32 persons with multiple sclerosis. Ratings about their degree of impairment and disability (Functional Systems, Expanded Disability Status Scale, Functional Independence Measure) was obtained from the multidisciplinary rehabilitation team. The individuals were interviewed using a questionnaire, mainly based on the items of the FIM scale, about the interference of Tremor during activities of daily life. Intention Tremor is rarely an isolated symptom. It is extremely disabling and was reported to interfere the most with activities of daily life such as eating, drinking, grooming and dressing. A variety of aids and strategies to compensate for specific disabilities were reported reflecting the important counseling role of the occupational therapist in assisting persons to cope more effectively with Tremor.
Peter Feys - One of the best experts on this subject based on the ideXlab platform.
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Is MS Intention Tremor Amplitude Related to Changed Peripheral Reflexes
ISRN neurology, 2011Co-Authors: Peter Feys, Werner Helsen, Stephan Ilsbroukx, Tom MeurrensAbstract:Intention Tremor is related to lesions in the cerebellum or connected pathways. Intention Tremor amplitude decreased after peripheral arm cooling in patients with multiple sclerosis (MS), likely caused by a reduction of muscle spindle afferent inflow, while amplitude increased when muscle spindles were artificially stimulated by tendon vibration. This study investigated the contribution of peripheral reflexes to the generation of MS Intention Tremor. Tendon reflexes of biceps, triceps, and brachioradialis, muscles were measured, using an electromechanical triggered reflex hammer. MS patients with (n = 17) and without (n = 17) upper limb Intention and 18 healthy controls were tested. Latency of brachioradialis, biceps, and triceps tendon reflexes was greater in MS patients with Tremor than in healthy controls and MS patients without Tremor (except for the triceps reflex). Peak and peak-to-peak amplitude were not different between groups. It is concluded that tendon reflexes were delayed but not enlarged in MS patients with Tremor.
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doi:10.5402/2011/192414 Research Article Is MS Intention Tremor Amplitude Related to Changed Peripheral Reflexes?
2011Co-Authors: Isrn Neurology, Peter Feys, Werner Helsen, Stephan Ilsbroukx, Tom MeurrensAbstract:Copyright © 2011 Peter Feys et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Intention Tremor is related to lesions in the cerebellum or connected pathways. Intention Tremor amplitude decreased after peripheral arm cooling in patients with multiple sclerosis (MS), likely caused by a reduction of muscle spindle afferent inflow, while amplitude increased when muscle spindles were artificially stimulated by tendon vibration. This study investigated the contribution of peripheral reflexes to the generation of MS Intention Tremor. Tendon reflexes of biceps, triceps, and brachioradialis, muscles were measured, using an electromechanical triggered reflex hammer. MS patients with (n = 17) and without (n = 17) upper limb Intention and 18 healthy controls were tested. Latency of brachioradialis, biceps, and triceps tendon reflexes was greater in MS patients with Tremor than in healthy controls and MS patients without Tremor (except for the triceps reflex). Peak and peakto-peak amplitude were not different between groups. It is concluded that tendon reflexes were delayed but not enlarged in MS patients with Tremor. 1
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Unsteady gaze fixation enhances the severity of MS Intention Tremor
Neurology, 2008Co-Authors: Peter Feys, Werner Helsen, Pierre Ketelaer, Bart Nuttin, Ann Lavrysen, Stephan P. Swinnen, Xiaoshun LiuAbstract:Background: Patients with arm Intention Tremor due to multiple sclerosis (MS) often manifest eye movement deficits, illustrating the role of infratentorial brain in both ocular and manual movement control. Our previous study showed that both the amplitude of Intention Tremor and eye fixational movements were greatly enhanced after coordinated eye-hand action toward stationary targets vs during hand movements with continuous target fixation. Objective: The present study tested, during coordinated step-tracking movements, the hypothesis that the amplitude of hand Intention Tremor was influenced by (unsteady) gaze fixation onto the target. Methods: Simultaneously recorded eye and hand tracking movements were compared between 13 MS patients with Intention Tremor and 14 healthy controls over conditions in which the magnitude of the primary eye and hand tracking movements, as well as their ratio, were altered. Results: Patients always made larger fixational eye movements around the visual targets than the controls. In the patient group, the size of fixational eye movements decreased following a reduction in the magnitude of the preceding saccadic movement, and most interestingly, was accompanied with a decrease in Tremor amplitude. An alteration in the magnitude of the primary hand movement did not affect the Tremor severity. Conclusions: In patients with multiple sclerosis with Intention Tremor, the unsteady gaze fixation on the visual targets is proportional to the magnitude of the preceding saccades, and influences the severity of Intention Tremor during eye-hand coordinated visuomotor tasks.
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Digitised spirography as an evaluation tool for Intention Tremor in multiple sclerosis.
Journal of neuroscience methods, 2006Co-Authors: Peter Feys, Werner Helsen, Stephan Ilsbroukx, Ann Prinsmel, Shouyan Wang, Xuguang LiuAbstract:This study investigated validity and reliability of digitised circle and square spiral drawing for quantifying Intention Tremor severity and related disability in patients with multiple sclerosis (MS). The Tremor amplitude was measured as the standard deviation of the drawing velocity of the arm in the radial and tangential direction for circle spiral drawing, and in the horizontal and vertical direction for square spiral drawing. Results were compared with those of MS patients without Tremor and healthy controls, and correlated with clinical assessments of Tremor severity and arm functionality including Fahn's Tremor rating scale, Test d'Evaluation des Membres superieurs des Personnes Agees (TEMPA) and the nine-hole-peg test to examine validity. Comparison of patient's performance between four repeated trials examined short-term test-retest reliability. All digitised spirography variables discriminated between the MS-Tremor and both MS-no-Tremor and healthy control groups. Validity was also shown by high spearman correlation coefficients between spirography variables and clinical ratings. Tremor appeared to be most profound in the radial and vertical direction during circle and square spiral drawing, respectively. The consistency and high correlations between four repeated executions indicated short-term test-retest reliability. We conclude that the digitised spirography provide a useful instrumentation for quantifying MS Intention Tremor.
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The effect of changed visual feedback on Intention Tremor in multiple sclerosis.
Neuroscience letters, 2005Co-Authors: Peter Feys, Werner Helsen, Pierre Ketelaer, Bart Nuttin, Martinus J. Buekers, Tanja Ceux, Elke Heremans, Xuguang LiuAbstract:In patients with multiple sclerosis (MS), Intention Tremor amplitude is enhanced during the visually guided compared to the memory guided motor tasks. In the present study, the effect of visual feedback on Intention Tremor was investigated during visually guided wrist step-tracking tasks. Specifically, visual feedback of the hand was provided either instantly or averaged over different time windows. Thirteen MS patients with Intention Tremor and 14 healthy controls performed the wrist step-tracking task, while the visual representation of the actual hand position was displayed instantly or averaged over time windows of 150, 250 and 350 ms. It has been found in the patient group that, in association with a decreased initial error and decreased Tremor amplitude on the screen, the amplitude of the actual performed Tremor also decreased when visual feedback was changed. The Tremor reduction was not different between conditions with manipulated feedback, although delays in presenting visual feedback of the hand position increased when the time window was larger. The reduction in overall Tremor amplitude was unlikely related to other factors, such as eye fixation deficits or the speed of the primary hand movement. These results suggest that hand Tremor severity is dependent on the visual feedback of position and movement errors.
Susan J Forwell - One of the best experts on this subject based on the ideXlab platform.
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upper limb Intention Tremor in multiple sclerosis an evidence based review of assessment and treatment
International journal of MS care, 2017Co-Authors: Keiko J Mccreary, James A Rogers, Susan J ForwellAbstract:Abstract Background: To present the current knowledge on the characteristics, assessment, and treatment of upper limb Intention Tremor to inform and improve future intervention studies in patients with multiple sclerosis (MS), we conducted a literature review for articles on upper limb Intention Tremor in patients with MS. Methods: Two reviewers conducted searches in PubMed, Web of Science, and MEDLINE (Ovid). Relevant articles, sorted on inclusion criteria, were examined for descriptions and assessments of upper limb Intention Tremor, and intervention studies were evaluated based on treatment type. Results: Eight descriptive studies were found reporting on the incidence and severity of Tremor, impairments, and lesion load. Ten studies focused on measurement of Tremor using various assessments. Intervention studies included eight articles using a diverse set of noninvasive techniques mainly showing transient reduction in Tremor amplitude and temporary increase in function. Eighteen studies on pharmacologi...
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interventions for upper limb Intention Tremor in multiple sclerosis
International journal of MS care, 2010Co-Authors: Frances Hawes, Carley Billups, Susan J ForwellAbstract:Approximately 25% of people with multiple sclerosis (MS) experience upper-limb Intention Tremor (ULIT), which limits their ability to participate in daily activities. Little research has been conducted on the effectiveness of available treatments for ULIT. The objectives of this study were to investigate the use of occupational therapy interventions to improve eating and handwriting performance in adults with MS and ULIT and, based on these findings, to provide recommendations for the development of a treatment protocol for ULIT. Six adults with MS and ULIT were recruited from an MS clinic. Participants rated their pre- and post-intervention functional performance using the Multi-Dimensional Assessment of Tremor. Interventions included education about Tremor, proximal stabilization, hand-over-hand technique, weighted tool, weighted wrist, and splinting. Participants evaluated the techniques using visual analogue scales (VASs). One month after the intervention, participants were interviewed to assess susta...
Günther Deuschl - One of the best experts on this subject based on the ideXlab platform.
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Deep brain stimulation in the subthalamic area is more effective than nucleus ventralis intermedius stimulation for bilateral Intention Tremor
Acta neurochirurgica, 2007Co-Authors: W. Hamel, Günther Deuschl, J. Herzog, F. Kopper, M. Pinsker, D. Weinert, D. Müller, P. Krack, H. M. MehdornAbstract:Background. The ventro-lateral thalamus is the stereotactic target of choice for severe Intention Tremor. Nevertheless, the optimal target area has remained controversial, and targeting of the subthalamic area has been suggested to be superior.
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Voxel-based morphometry shows no decreases in cerebellar gray matter volume in essential Tremor.
Neurology, 2006Co-Authors: C. Daniels, Martin Peller, Stephan Wolff, K. Alfke, Karsten Witt, Christian Gaser, Olav Jansen, Hartwig R. Siebner, Günther DeuschlAbstract:Objective: To investigate cerebellar gray matter volume in patients with essential Tremor (ET). Methods: We used voxel-based morphometry (VBM) based on high-resolution T1-weighted MRI to compare gray and white matter density between 27 patients with ET and 27 age- and sex-matched healthy control subjects. Fourteen patients had only postural Tremor, whereas 13 patients showed additional Intention Tremor. Results: VBM failed to demonstrate regional decreases in gray and white matter volume in patients with ET. There was, however, an expansion in gray matter depending on the type of Tremor. Compared with age-matched control groups, patients with Intention Tremor showed a relative expansion of gray matter bilaterally in the region of the temporoparietal junction and the right middle occipital cortex. Conclusions: The lack of a consistent decrease in gray and white matter density argues against a progressive neurodegenerative process in essential Tremor that leads to a substantial decrease in cerebellar gray matter volume. Patients with predominant Intention Tremor show a relative expansion of gray matter areas involved in higher order visuospatial processing, which might represent a long-term result of adaptive reorganization compensating the higher demands on the visuospatial control of skilled movements in case of trembling.
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Eye movement abnormalities in essential Tremor may indicate cerebellar dysfunction
Brain, 2003Co-Authors: C Helmchen, R. Wenzelburger, A Hagenow, J Miesner, A Sprenger, H Rambold, W Heide, Günther DeuschlAbstract:Summary Experimental and clinical data indicate that the cerebellum is involved in the pathophysiology of advanced stages of essential Tremor (ET). The aim of this study was to determine whether a dysfunction also affects cerebellar structures involved in eye movement control. Eye movements of 14 patients with ET and 11 agematched control subjects were recorded using the scleral search-coil technique. Vestibular function was assessed by electro-oculography. Eight ET patients had clinical evidence of Intention Tremor (ETIT); six had a predominantly postural Tremor (ETPT) without Intention Tremor. ET patients showed two major deficits that may indicate cerebellar dysfunction: (i) an impaired smooth pursuit initiation; and (ii) pathological suppression of the vestibulo-ocular reflex (VOR) time constant by head tilts (‘otolith dumping’). In the step ramp smooth pursuit paradigm, the initial eye acceleration in the first 60 ms of pursuit generation was significantly reduced in ET patients, particularly in ETIT patients, by ~ 44% (mean 23.4∞/s 2 ) compared with that of control subjects (mean 41.3∞/s 2 ). Subsequent steady-state pursuit velocity and sinusoidal pursuit gain (e.g. 0.4 Hz: 0.90 versus 0.78) were also significantly decreased in ET patients, whereas pursuit latency was unaffected. The Intention Tremor score correlated with the pursuit deficit, e.g. ETIT patients were significantly more affected than ETPT patients. Gain and time constant (t) of horizontal VOR were normal, but suppression of the VOR time constant by head tilt (‘otolith dumping’) was pathological in 41% of ET patients, particularly in ETIT patients. Saccades and gaze-holding function were not impaired. The deficit of pursuit initiation, its correlation with the intensity of Intention Tremor, and the pathological VOR dumping provide additional evidence of a cerebellar dysfunction in the advanced stage of ET, when Intention Tremor becomes part of the clinical symptoms, and point to a common pathomechanism. The oculomotor deficits may indicate an impairment of the caudal vermis in ET.
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Essential Tremor and cerebellar dysfunction Clinical and kinematic analysis of Intention Tremor
Brain, 2000Co-Authors: Günther Deuschl, R. Wenzelburger, Klaus Löffler, Jan Raethjen, Hannah StolzeAbstract:The cerebellum is assumed to play a major role in the pathophysiology of essential Tremor (ET). As Intention Tremor is considered one of the classical features of cerebellar disease, we have assessed a large group of patients with ET for the semiology of the Tremor and have performed objective quantitative analysis of a grasping movement in patients with ET, cerebellar disease and a normal control group. We found 25% of the patients to have a moderate or severe kinetic Tremor with clear-cut features of a classical Intention Tremor. Another 33% of the patients had a mild Intentional component of their kinetic Tremor. Patients with Intention Tremor (ETIT) did not differ from those with predominant postural Tremor (ETPT) with respect to alcohol sensitivity of the Tremor and the frequency of a family history. ETIT patients were older and more often showed head and trunk involvement. The onset of this Intention Tremor has been assessed retrospectively. It was found to begin at a randomly distributed time interval after the onset of the postural Tremor, but older patients had a shorter time to development of Intention Tremor. Quantitative accelerometry of postural Tremor showed similar Tremor frequencies in both patient groups, but ETIT patients had a slightly larger Tremor amplitude. Quantitative analysis of a grasping movement using an infrared-camera system was performed in two subgroups of the patients with ETPT and ETIT and control groups with cerebellar disease or normal subjects. The Intention Tremor could be quantified objectively as an increased amplitude of curvature during the deceleration and target phase of the movement. The amplitude measurements of Intention Tremor were clearly abnormal and of comparable magnitude for ETPT and cerebellar disease. Additionally, the patients with ETIT had a significantly slowed grasping movement during the deceleration and target period. Hypermetria was significantly increased for the patients with ETIT and cerebellar disease. We conclude that Intention Tremor is a feature of ET. ETIT patients have abnormalities of their upper limb function compatible with cerebellar disease. This suggests that patients with more advanced ET show abnormalities of cerebellar functions.
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Differential diagnosis of Tremor.
Journal of Neural Transmission-supplement, 1999Co-Authors: Günther DeuschlAbstract:The differential diagnosis of Tremor is based on the clinical distinction of rest, postural and Intention Tremor and the presence of additional clinical signs and data from the medical history. The most common pathological Tremors are essential Tremor and the Tremors of Parkinson’s disease. Among the patients with essential Tremor those with Intention Tremor are often misdiagnosed as cerebellar Tremors. Patients with monosymptomatic resting Tremors represent a special subgroup of Parkinson’s disease. Primary orthostatic Tremor and dystonic Tremor are rare clinical syndromes which have recently been well defined. Holmes’ Tremors are defined by their low frequency and the occurence of resting and Intention Tremor. Palatal Tremor can be separated into two subgroups. Psychogenic Tremor can be diagnosed on the basis of clinical criteria. The gold standard of Tremor differential diagnosis is still based on clinical criteria.
Werner Helsen - One of the best experts on this subject based on the ideXlab platform.
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Is MS Intention Tremor Amplitude Related to Changed Peripheral Reflexes
ISRN neurology, 2011Co-Authors: Peter Feys, Werner Helsen, Stephan Ilsbroukx, Tom MeurrensAbstract:Intention Tremor is related to lesions in the cerebellum or connected pathways. Intention Tremor amplitude decreased after peripheral arm cooling in patients with multiple sclerosis (MS), likely caused by a reduction of muscle spindle afferent inflow, while amplitude increased when muscle spindles were artificially stimulated by tendon vibration. This study investigated the contribution of peripheral reflexes to the generation of MS Intention Tremor. Tendon reflexes of biceps, triceps, and brachioradialis, muscles were measured, using an electromechanical triggered reflex hammer. MS patients with (n = 17) and without (n = 17) upper limb Intention and 18 healthy controls were tested. Latency of brachioradialis, biceps, and triceps tendon reflexes was greater in MS patients with Tremor than in healthy controls and MS patients without Tremor (except for the triceps reflex). Peak and peak-to-peak amplitude were not different between groups. It is concluded that tendon reflexes were delayed but not enlarged in MS patients with Tremor.
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doi:10.5402/2011/192414 Research Article Is MS Intention Tremor Amplitude Related to Changed Peripheral Reflexes?
2011Co-Authors: Isrn Neurology, Peter Feys, Werner Helsen, Stephan Ilsbroukx, Tom MeurrensAbstract:Copyright © 2011 Peter Feys et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Intention Tremor is related to lesions in the cerebellum or connected pathways. Intention Tremor amplitude decreased after peripheral arm cooling in patients with multiple sclerosis (MS), likely caused by a reduction of muscle spindle afferent inflow, while amplitude increased when muscle spindles were artificially stimulated by tendon vibration. This study investigated the contribution of peripheral reflexes to the generation of MS Intention Tremor. Tendon reflexes of biceps, triceps, and brachioradialis, muscles were measured, using an electromechanical triggered reflex hammer. MS patients with (n = 17) and without (n = 17) upper limb Intention and 18 healthy controls were tested. Latency of brachioradialis, biceps, and triceps tendon reflexes was greater in MS patients with Tremor than in healthy controls and MS patients without Tremor (except for the triceps reflex). Peak and peakto-peak amplitude were not different between groups. It is concluded that tendon reflexes were delayed but not enlarged in MS patients with Tremor. 1
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Unsteady gaze fixation enhances the severity of MS Intention Tremor
Neurology, 2008Co-Authors: Peter Feys, Werner Helsen, Pierre Ketelaer, Bart Nuttin, Ann Lavrysen, Stephan P. Swinnen, Xiaoshun LiuAbstract:Background: Patients with arm Intention Tremor due to multiple sclerosis (MS) often manifest eye movement deficits, illustrating the role of infratentorial brain in both ocular and manual movement control. Our previous study showed that both the amplitude of Intention Tremor and eye fixational movements were greatly enhanced after coordinated eye-hand action toward stationary targets vs during hand movements with continuous target fixation. Objective: The present study tested, during coordinated step-tracking movements, the hypothesis that the amplitude of hand Intention Tremor was influenced by (unsteady) gaze fixation onto the target. Methods: Simultaneously recorded eye and hand tracking movements were compared between 13 MS patients with Intention Tremor and 14 healthy controls over conditions in which the magnitude of the primary eye and hand tracking movements, as well as their ratio, were altered. Results: Patients always made larger fixational eye movements around the visual targets than the controls. In the patient group, the size of fixational eye movements decreased following a reduction in the magnitude of the preceding saccadic movement, and most interestingly, was accompanied with a decrease in Tremor amplitude. An alteration in the magnitude of the primary hand movement did not affect the Tremor severity. Conclusions: In patients with multiple sclerosis with Intention Tremor, the unsteady gaze fixation on the visual targets is proportional to the magnitude of the preceding saccades, and influences the severity of Intention Tremor during eye-hand coordinated visuomotor tasks.
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Digitised spirography as an evaluation tool for Intention Tremor in multiple sclerosis.
Journal of neuroscience methods, 2006Co-Authors: Peter Feys, Werner Helsen, Stephan Ilsbroukx, Ann Prinsmel, Shouyan Wang, Xuguang LiuAbstract:This study investigated validity and reliability of digitised circle and square spiral drawing for quantifying Intention Tremor severity and related disability in patients with multiple sclerosis (MS). The Tremor amplitude was measured as the standard deviation of the drawing velocity of the arm in the radial and tangential direction for circle spiral drawing, and in the horizontal and vertical direction for square spiral drawing. Results were compared with those of MS patients without Tremor and healthy controls, and correlated with clinical assessments of Tremor severity and arm functionality including Fahn's Tremor rating scale, Test d'Evaluation des Membres superieurs des Personnes Agees (TEMPA) and the nine-hole-peg test to examine validity. Comparison of patient's performance between four repeated trials examined short-term test-retest reliability. All digitised spirography variables discriminated between the MS-Tremor and both MS-no-Tremor and healthy control groups. Validity was also shown by high spearman correlation coefficients between spirography variables and clinical ratings. Tremor appeared to be most profound in the radial and vertical direction during circle and square spiral drawing, respectively. The consistency and high correlations between four repeated executions indicated short-term test-retest reliability. We conclude that the digitised spirography provide a useful instrumentation for quantifying MS Intention Tremor.
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The effect of changed visual feedback on Intention Tremor in multiple sclerosis.
Neuroscience letters, 2005Co-Authors: Peter Feys, Werner Helsen, Pierre Ketelaer, Bart Nuttin, Martinus J. Buekers, Tanja Ceux, Elke Heremans, Xuguang LiuAbstract:In patients with multiple sclerosis (MS), Intention Tremor amplitude is enhanced during the visually guided compared to the memory guided motor tasks. In the present study, the effect of visual feedback on Intention Tremor was investigated during visually guided wrist step-tracking tasks. Specifically, visual feedback of the hand was provided either instantly or averaged over different time windows. Thirteen MS patients with Intention Tremor and 14 healthy controls performed the wrist step-tracking task, while the visual representation of the actual hand position was displayed instantly or averaged over time windows of 150, 250 and 350 ms. It has been found in the patient group that, in association with a decreased initial error and decreased Tremor amplitude on the screen, the amplitude of the actual performed Tremor also decreased when visual feedback was changed. The Tremor reduction was not different between conditions with manipulated feedback, although delays in presenting visual feedback of the hand position increased when the time window was larger. The reduction in overall Tremor amplitude was unlikely related to other factors, such as eye fixation deficits or the speed of the primary hand movement. These results suggest that hand Tremor severity is dependent on the visual feedback of position and movement errors.
