Online movement control in multiple sclerosis patients with tremor: effects of tendon vibration.

Patients with intention tremor due to multiple sclerosis (MS) exhibit an increased reliance on visual feedback in the sensorimotor control of slow goal-directed movements. In the present study, the use of proprioceptive information was investigated in MS patients with intention tremor compared to MS patients without tremor and healthy controls. Tendon vibration was applied to the wrist extensor muscles during a memory-guided slow wrist step-tracking task to investigate the use of muscle spindle afferent information in online movement control. A significant reduction of movement amplitude was induced by tendon vibration in all three groups, but the effect was found to be smaller in MS patients with tremor (28%) than in subjects without tremor (50%). Vibration also induced an increase of overall tremor amplitude in the MS tremor group; however, its effect on movement amplitude was not directly related to (changes in) tremor severity. The results suggest that the decreased online use of proprioceptive information in MS patients with tremor reflects an adaptation over time to cope with a tremor-related noisy background. Abnormalities in proprioceptive processing may explain why MS patients with tremor show an increased reliance on visual feedback for online motor control.

Clinical characteristics and long term prognosis in early onset multiple sclerosis.

The clinical features, disease course and long term prognosis of early onset multiple sclerosis (EOMS) are variable. A preponderance of female sex, a high incidence of visual and brainstem symptoms at onset and a relapsing-remitting disease course with slower progression rate all have been considered relatively frequent in this subgroup of MS patients. Unfortunately, follow-up in previous studies has usually been limited to less than 10 years, precluding general statements on the long term evolution and prognosis in EOMS. In this retrospective study of EOMS with a substantially longer follow-up of 20.8 years, clinical characteristics, disease course and long term prognosis are described in 49 EOMS patients. In a representative subgroup of 28 patients disability was scored using Kurtzke's Functional System (FS) and Expanded Disability Status Scale (EDSS). The mean period of follow- up for these patients was 28.7 years. The present study confirms that several specific clinical characteristics can be identified in EOMS patients, such as a mainly relapsing-remitting disease onset and frequent presentation with brainstem- cerebellar dysfunction (28.6 %), pyramidal symptoms (18.4 %) and optic neuritis (14.3%). However, after a long period of follow-up the overall disease course and prognosis do not seem to differ from that in adult onset MS. By consequence a young age at onset in MS cannot be considered a favourable prognostic factor.

The effect of changed visual feedback on intention tremor in multiple sclerosis.

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.

Interaction between eye and hand movements in multiple sclerosis patients with intention tremor.

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.

Self-report assessment of fatigue in multiple sclerosis: a critical evaluation.

SUMMARY Fatigue is among the most common and disabling symptoms of multiple sclerosis. Clinicians usually assess fatigue by asking people to describe and rate their fatigue in a self-report instrument. This paper evaluates the clinical usefulness and the scientific properties of a selection of various self-report instruments for fatigue. To be selected, instruments had to assess fatigue or a related concept, have some published information on reliability and validity, be used in at least one clinical trial of fatigue with people with multiple sclerosis, and demonstrate validity in people with MS. Five fatigue specific scales and four subscales of quality of life instruments were selected and evaluated. In occupational therapy, the fatigue subscales or items of quality of life measurements give limited information about the quality of fatigue. The selection of an instrument may depend on the clinical setting or trial design.

Interference of upper limb tremor on daily life activities in people with multiple sclerosis.

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.

Intention tremor rated according to different finger-to-nose test protocols: a survey.

OBJECTIVES: To investigate the dependence of intention tremor rating scores on different finger-to-nose test (FNT) protocols, varying in arm position and the time the finger has to be kept on the nose, and to examine their relevance to function. DESIGN: Observational survey. Video recordings were made while patients performed the FNTs and functional tasks such as pouring water. SETTING: Three European rehabilitation centers in Belgium, Finland, and England. PARTICIPANTS: Twenty-six multiple sclerosis patients with intention tremor (avg age, 44.1y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Six examiners rated the degree of intention tremor by using the Fahn Tremor Rating Scale. RESULTS: Interrater reliability for rating intention tremor during the FNTs was high (kappa=.65-.74). Both the required arm position and time constraints affected the magnitude of intention tremor rating scores (mean rank, 2.27-2.95) and their functional relevance (rho=.70-.84). Intention tremor was scored the highest when the arm was lifted to 90 degrees of abduction at the shoulder and the subject was required to stabilize the finger on the nose. However, its functional relevance was lower compared with a more "functionally" executed FNT. CONCLUSIONS: The rating of intention tremor during the FNT depends on test instructions. A standardized protocol is needed.

Assessing fatigue in multiple sclerosis: Dutch modified fatigue impact scale.

The aim of this study is to evaluate the reliability, validity and responsiveness of the Dutch version of the Modified Fatigue Impact Scale. Fifty-one randomly selected subjects with definite multiple sclerosis (MS) (mean age 51.9 +/- 10.5 years, 25 women) and 20 healthy controls (mean age 50.6 +/- 14.0 years, 13 women) filled in the Modified Fatigue Impact Scale (MFIS), the Fatigue Severity Scale (FSS) and the fatigue subscale of Guy's Neurological Disability Scale (GNDS). All tests were repeated with an interval of maximum three days. The hospitalised individuals with MS (n = 20) were assessed at intake and discharge. No significant difference was found between first and second administration of MFIS (z = -.519, p = .603, Wilcoxon signed ranks test), with a good correlation (.729). MFIS was able to distinguish individuals with MS from controls, and subjects with fatigue from the non-fatigued group. MFIS showed no floor or ceiling effect. MFIS correlated moderately with Fatigue Severity Scale (.447) and the fatigue subscale of GNDS (.487). The 20 hospitalised subjects had significant lower MFIS scores (z = -3.401, p = .001) after a four-week rehabilitation programme, whereas the FSS did not change. This study indicates that the Dutch version of the MFIS is a reliable, valid and responsive tool to assess the impact of MS-related fatigue on daily life.