title: The effect of topical anaesthesia on hand tremor in man
Creators: name: Badghish, Mohammed Salem
Publisher: name: University of Glasgow
Year: 2005
Subjects: subject: Pharmacology.

description: Tremor is the most common movement disorder met in clinical practice. Tremor is defined as an involuntary, rhythmic oscillation of a body region. Not all tremors are pathological. Tremor often causes occupational disability. It can affect the head and lower limbs but it mainly affects the upper limbs. Tremor is an interesting physiological phenomenon, which is present in all living organisms. It can also seen as a symptom of underlying dysfunction of the nervous system. At first sight tremor looks simple but in fact it is a most complex physiological phenomenon. There are a number of different types of tremor, which are often confused with one another. This presents a practical problem for differential diagnosis and clinical management. Currently, tremor can be classified into rest and action tremors. Action tremors can be subdivided into postural, kinetic, intention and task specific types. Accurate diagnosis of tremor is important to both patient and clinician because the assessment of prognosis and the selection of treatment depend on the type of tremor. Electromyography and accelerometry are reliable and convenient techniques that are widely employed in the study of tremor. They have been used to measure tremor frequency, amplitude and other characteristics. The amplitude of most tremors is very variable. In contrast, the frequency of tremor is quite stable. The underlying causes of tremor have been investigated by many authors but the mechanisms causing tremors remain unclear. However, the precise mechanisms of tremor generation are not so important in this project. The principal question raised in this project was: does topical anaesthesia have a significant action on tremor amplitude? Pozos and laizzo (1992) investigated the effect topical anaesthesia on essential tremor of the hand. In an earlier study Pozos and Mills (1985) investigated the effect of topical anaesthesia on clonus, resting physiological tremor and physiological action tremor of the ankle joint. Both of these studies reported significant decrease in tremor amplitude after the application of topical anaesthesia. In contrast, the data presented in this thesis clearly show that there was no significant effect by either the placebo or topical anaesthesia on the magnitude of postural tremors, during movement or in a small number of case studies. The effects of topical anaesthesia or a placebo spray on hand tremor were investigated in a total of 37 volunteers. Postural tremor was studied in 19 subjects. Movement tremor was studied in 12 subjects. Six cases pathological tremor were also investigated. The volunteers were blinded to the nature of the spray, which had been applied to their skin of the upper limb. Hand tremors were recorded by using a two-axis accelerometer (ADXL210E Analog Devices) that was attached to the middle finger of right hand. Electromyogram recordings were made from flexor and extensor muscle groups of forearm at the same time. The tremor acceleration and electromyography were recorded, digitised and stored on PC. Subsequently, the power spectrum of the tremor was calculated. The tremor energy in four bands, 2-6 Hz, 6-12 Hz, and 12-20 Hz and the total band 2-20 Hz were studied. The electromyogram was filtered and its root mean square value was calculated. A Bland Altman analysis was employed to investigate the mean difference of the signals after application of a topical anaesthetic or placebo spray. The confidence interval of the mean difference was calculated. If the confidence interval did not contain zero, the difference was statistically significant. In all these band frequencies studied no significant difference was found between the tremor after application of xylocaine and placebo sprays. The results of these studies are that skin anaesthesia did not change tremor amplitude. It is concluded that topical anaesthesia is not likely to be useful as a tool for the clinical management of tremor.