Myoclonus

Myoclonus, a diagnostic challenge

Myoclonus is a frequently encountered hyperkinetic movement disorder characterized by involuntary jerks, or short interruptions of muscle tone.1 Myoclonus can be anatomically classified into cortical, subcortical, spinal, and peripheral myoclonus2, as well as forming a component of functional movement disorders.3,4 Myoclonus can be present in a large number of both acquired and genetically determined disorders. Accurate diagnosis and classification of its anatomical subtype is important in determining an aetiological differential diagnosis, and guiding therapeutic management. However, clinical diagnosis of myoclonus remains challenging due to its manifestation in a large number of clinical phenotypes, and the number of causative disease causing genes increasing year on year. These challenges and opportunities reinforce the need for a novel and systematic approach to those patients presenting with myoclonus. This thesis provides a new diagnostic approach for patients who present with myoclonus. We describe the challenges and importance of accurate clinical phenotyping, classification of the anatomical myoclonus subtype, and recognition of the frequently accompanying non-motor characteristics. Electrophysiological testing including video-polymyography and advanced techniques (e.g. back-averaging and coherence analysis) proved to play an important contributing role in determining an accurate diagnosis. These, together with the development and wider application of ERD may also demonstrate future applicability in the diagnosis of highly complex hyperkinetic movement disorders, and in particular functional movement disorders.

Dissertation: http://hdl.handle.net/11370/5001c9ad-e831-4925-84ce-44124dfb6738