الفهرس 
TREMOR; BASICS AND CLASSIFICATIONSOnly 14 pages are availabe for public view
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Abstract
E
ssential tremor (ET) is one of the most common neurological disorders and is the most common tremor disorder. It is characterized by the presence of action tremor of the hands.
Till recently our understanding of the pathophysiology of Essential Tremor (ET) has been limited, despite ET being one of the commonest movement disorders.
Abnormalities in the cerebellothalamocortical loop (ie, Purkinje torpedoes) and the locus ceruleus (ie, Lewy bodies) have been implicated in the neuropathogenesis of ET.
Because patients with ET are five times more likely to have first degree relatives with tremor compared to the general population, it is largely considered a genetic disorder.
The genetics of ET, however, are not yet clear. In a significant number of cases, ET is hereditary and transmitted in an autosomal dominant pattern. Mutations in chromosome 2p22-25, 3q13, 6p23, and the fused in sarcoma (FUS) gene have been suggested to be the disease loci in some of these dominantly inherited families, though there are families with dominantly inherited ET without a link to these loci.
There is a growing evidence to suggest that apart from motor features, patients with Essential Tremor (ET) may have significant non-motor features, patients with ET have been reported to have cognitive abnormalities characterized by mild frontal dysfunction that may have a functional impact, an association with dementia (both prevalent and incident) among those with late onset of tremor (>65 years), a higher prevalence of anxiety and an anxious and worrisome personality type, depressive symptomatology and may even have depression as a premotor symptom, poor sleep quality, subjective hearing impairment and reduced quality of life (QoL).
The biological basis for each of these observations requires further clarification and some findings need confirmation in population-based studies.
Studies have only recently begun to explore the effects of ET on health status and health-related quality of life (QoL), which describe an individual’s perception of the effects of a disease on their level of general health, sense of well-being, and everyday functioning. The former concepts focus on the patient’s perspective regarding the manner in which the disease impacts their physical and psychosocial health and well-being, whereas the latter refers more narrowly to one’s ability to perform ADLs.
Predictors of lower health status and QoL in ET include greater tremor severity older age, and personality factors, such as neuroticism and social introversion.
Although depression, anxiety, and social phobia impact functioning independent of tremor severity no prior studies have examined the relationship between health status and neuropsychiatric features and cognitive impairment, which are strong predictors of ADLs in other neurologic conditions, The contributions of these non motor factors may provide insights into targeted areas to improve perceived health status and QoL in ET.
Our study aimed at investigating non-motor features in patients with ET and their impact on quality of life using Non motor symptoms scale (NMSS), Montreal Cognitive Assessment (MoCA), Beck Depression Inventory (BDI), Hamilton anxiety rating scale (HARS), Pittsburgh Sleep quality index (PSQI) and The Short Form 36 Health Survey Questionnaire.
Comparison of neuropsychiatric symptoms between ET patients and controls showed that score means of all tests were significantly higher in the ET group than those of the controls.
Regarding cognition, Montreal Cognitive assessment total score means were 25.73 ± 3.04 in the ET group and were 27.40 ± 2.34 in the control group which is significantly higher in ET than controls (p = 0.021).
Regarding depression, Beck Depression inventory score means were 13.33 ± 6.002 in ET patients and were 8.77 ± 4.16 in control group which is significantly higher in ET than controls (p = 0.001).
Regarding anxiety, Hamilton anxiety rating scale score means were 15.67 ± 6.25 in ET patients and were 9.70 ± 4.47 in control group which is significantly higher in ET than controls, (p = <0.001).
Regarding sleep, Pittsburgh sleep quality index score means were 6.13 ± 2.87 in ET patients and were 4.40 ± 2.53 in control group, which is significantly higher in ET than controls (p =0. 016).
Comparison of Non Motor Symptoms Scale between ET patients and controls showed that score means of all domains were statistically highly significant in the ET group than those of the controls (p = > 0.001) except perceptual problems (p=0.003), gastrointestinal tract (p=0.010) and urinary symptoms (p=0.043) were moderately significant.
Non motor symptoms total score means were 58.033 ± 21.50 in ET patients while were 17.20 ± 11.80 in control group which is significantly higher in ET than controls, (p = <0.001).
Comparison of Quality of life between ET patients and controls showed that ET patient showed statistically highly significant impairment (lower scores) on all QoL subscales on comparison to control group (p=<0.001).
Correlations of neuropsychiatric and non motor symptoms with age, duration and severity of tremor showed that depression, anxiety and quality of sleep showed no correlation with age, illness duration nor with severity of tremor except that depression was positively correlated with severity of tremor (p=0.033, r=0.389).
There was a negative correlation between MOCA total scores and age (p=>0.001, r=- 0.612), positive correlation with age of illness (p=>0.001, r=0.691) but there was no correlation with illness duration nor with severity of tremor.
Correlation analysis showed that Non motor symptoms domains were not correlated with age of the patients, illness duration nor with severity of tremor except that age of the patients was positively correlated with fatigue (p=0.003, r=0.525) and severity of tremor was positively correlated with Cardiovascular domain (p=0.001, r=0.567) and with Attention and memory (p=0.003, r=0.519).
Lack correlation of presence or severity of non motor features with age of patients, duration of illness and severity of tremor may support the hypothesis that Non-motor Manifestations in ET are primary disease features rather than secondary phenomena.
All quality of life subscales were negatively correlated with FTM rating scale total score except social functioning showed no correlation (p=0.059, r=0.348), it was found to be correlated with Tremor severity measured by (Domain A) more than handwriting measured by Domain B and functional disability due to tremors measured by Domain C, which means increased severity of tremor leads to more impairment and poor general health status.
All quality of life subscales were negatively correlated with depression while physical functioning, mental health, limitations due to physical health and emotional problems were negatively correlated with anxiety.
Role limitations due to emotional problems were negatively correlated with sleep quality index scores (p=0.022, r=-0.417) and mental health was positively correlated with MoCA scores (p=0.004, r=0.515).
All quality of life subscales were negatively correlated with domains of non motor symptoms which means that increased severity of non motor symptoms is associated with more impairment, except Perceptual Problems, Gastrointestinal tract and Urinary symptoms showed no correlation with QoL.
Linear regressions were performed to evaluate the predictive value of the NMS in determining general QoL.
The NMS total score was found to be significantly related to overall well-being, physical, emotional and intellectual for patients with ET.
Attention and Memory were found to be significantly associated with intellectual well-being (mental health) (p=0.013) and with Limitation of activities (RP) (p=0.023).
The presence of numerous non motor features in ET is increasingly evident. ET can no longer be considered as a purely motor disorder. Several non motor symptoms have an impact on quality of life. In our view, the significant neuropsychiatric deficits and reduced QoL of ET patients particularly at young age demonstrate a degree of illness that may be regarded as a non-motor phenotype rather than a secondary effect of motor symptoms.
Further studies are required to clarify the non-motor phenotype in ET and learn more about the development and course of the reported abnormalities.
Non motor features should be considered in the clinical evaluation and management of ET.