Functional Assessment and Electromyographic Patterns in Focal Hand Dystonia

Ajith, Sivadasan (2010) Functional Assessment and Electromyographic Patterns in Focal Hand Dystonia. Masters thesis, Christian Medical College, Vellore.


Download (1MB) | Preview
[img] Spreadsheet

Download (45kB)
[img] Spreadsheet

Download (52kB)

Download (14kB) | Preview


INTRODUCTION: Treatment options for FHD still remain limited and suboptimal. Surface EMG provides a rational approach to clinical assessment and could guide selection and monitoring of appropriate therapy in subjects with Focal Hand Dystonia. However, data on the EMG patterns are relatively scarce. The correlation of the various electrophysiological phenomenon can have important treatment implications and evolve novel therapies. OBJECTIVES: To study the ontogeny, recruitment pattern, motor activity and spread of flow of muscle contractions during different phases of a “writing task” using surface EMG recordings in the distal, intermediate and proximal group of muscles in both the upper limbs and correlate the EMG parameters with functional disability. METHODS: Surface EMG was obtained from 4 pairs of muscles in both the upper limbs using 16 channels. Recording and analysis of the data was done using customized software. FHD group was compared with normative controls with regard to EMG patterns obtained during the phases (rest, anticipation of writing, writing, relaxation) of the “writing task”. Burke Fahn Marden scale was used as an index for severity of dystonia. Rectified mean SEMG was calculated. Ontogeny, recruitment, flow of activity and mirror movements were analyzed. Legibility and speed of writing were indicators for functional disability. Student ‘t’ test and Chi-square test were used for group comparisons. Mann-Whitney test was used for non-parametric variables. RESULTS: Total of 36 subjects (20 FHD and 16 controls) were included. 50% of the FHD group was treatment naïve, 70% had FMS 3 dystonia and 45% had illegible handwriting. Mean time taken for writing was significantly longer in FHD (8’6” versus 3’25”). “Early onset” during anticipatory phase was seen in 60%, mean time being 32.4 seconds. The EMG amplitudes were significantly higher during writing, “delayed offset” was also seen in 90%, mean time 33 seconds. Rapid recruitment was noted, there was faster spread of activity to EDC, TRPZ and BIC. Mirror movements were identified in 100%, higher EMG amplitudes were also noted in the normal limb compared to controls. Spectral analysis showed higher percentage shift in Mean Frequency of EMG towards lower frequency in the FHD group – could be an indicator of fatigue. FMS correlated best with functional disability. CONCLUSION: These observations have important pathophysiological and therapeutic implications. They point to abnormalities in the central motor drive bilaterally, abnormal SMO and impaired inhibitory mechanisms. Combining TMS, functional imaging with EMG can characterize and delineate the basis of ontogeny further - the importance being, to see if one could devise treatment strategies like EMG guided denervation, rTMS, Bio-feedback, peripheral FES designed to ameliorate this functional disability.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Focal Hand Dystonia, Functional Assessment, Electromyographic Patterns.
Subjects: MEDICAL > Neurology
Depositing User: Subramani R
Date Deposited: 11 Feb 2020 01:11
Last Modified: 11 Feb 2020 01:11

Actions (login required)

View Item View Item