LIFESCI 3K03 Lecture Notes - Lecture 14: Derangement, Thalamus, Muscle Tone
27 Feb 2018
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Distribution: distal prominent in hands, feet, and face. There is a spike wave in the eeg, and a giant somatosensory evoked potential. Eeg back- averaging time-locked short latency (~30 ms for hand) cortical correlate preceding movement. Dystonia = a syndrome of sustained muscle contration, frequently causing twisting and repetitive movements, or abnormal postures (co-contraction of agonist and antagonist). It involves reduced inhibition at multiple levels: the muscles, the spinal cord, the brainstem, the cortex and the basal ganglia. We are not entirely sure what causes it but it is likely due to functional disturbance of the basal ganglia, causing altered thalamic control of cortical motor areas. The normal reciprocal innervation of opposing muscles allows for smooth muscle movements. Stimulus to the radial nerve (to forearm extensors) inhibits h-reflex of forearm flexor muscles (median nerve, flexor capri radialis). The abnormalities are present in both the affected and unaffected sides.
