Clinical Neurophysiology Sensory and Motor Systems PDF

Clinical Neurophysiology Part VII Sensory pathways and motor systems Karsten Schwerdtfeger Klinik für Neurochirurgie, Universitätsklinikum des Saarlandes. Studiengang: Neural Engineering Master WS 2024/2025  Somatosensory pathway Thal...

Clinical Neurophysiology Part VII Sensory pathways and motor systems Karsten Schwerdtfeger Klinik für Neurochirurgie, Universitätsklinikum des Saarlandes. Studiengang: Neural Engineering Master WS 2024/2025  Somatosensory pathway Thalamus Medulla oblongata Spinal cord Somatosensory pathway Electrophysiological assessment of – the peripheral nerve ? Somatosensory pathway Electrophysiological assessment of – the peripheral nerve Sensory electroneurography, ? Somatosensory pathway Electrophysiological assessment of – the peripheral nerve Sensory electroneurography, H-reflex and ? Somatosensory pathway Electrophysiological assessment of – the peripheral nerve Sensory electroneurography, H-reflex and Short-latency SEP Somatosensory pathway Electrophysiological assessment of – the ascending tract ? Somatosensory pathway Electrophysiological assessment of – the ascending tract Short-latency SEP Somatosensory pathway Electrophysiological assessment of – primary cortex ? Somatosensory pathway Electrophysiological assessment of – primary cortex – Short-latency SEP Somatosensory pathway Electrophysiological assessment of – Seondary/association cortex ? Somatosensory pathway Electrophysiological assessment of – Seondary/association cortex middle-latency SEP Event related EPs  Somatosensory pathway Thalamus Medulla oblongata Spinal cord  Somatosensory pathway Proprioceptive and Epicritic pathway Protopathic pathway  Somatosensory pathway Electrophysiological assessment of – Protopathic pathway Thalamus ? Medulla oblongata Spinal cord  Somatosensory pathway Electrophysiological assessment of – Protopathic pathway Thalamus Specific stimulation Laser Thermic stimuli – not Medulla oblongata applicable Long and intense Spinal cord electrical impulse (> 1 msec) – not selective Only used for studies  Afferent pathway Descending modulation – Mainly inhibitory – Downwards to spinal levels (spinothalamic tract) – Sensitivity control of peripheral receptors?  Afferent pathway information processing Alertness Amplification - convergence/divergence LCCS/ARAS-activation via the unspecific thalamus Cortico-thalamo-cortical loops Processing Spatial and temporal resolution in primary and secondary cortex Integration of different inputs in tertiary cortex Comparison with memory contents Response Preparation of complex motor programs (flight, attack, grip, speech….) Modulation Habituation (with the exception of pain) Lateral inhibition at various levels Descending input control Motor Systems Motor cortex – Association cortex Complex information processing in order to prepare complex movements for example speech – Supplementary motor area Preparing and designing movements – Premotor cortex Preparing and designing movements – Primary motor cortex Execution of movements (Homunculus) Motor Pathways Corticospinal (pyramidal) tract – one of several motor systems – Fast execution of movement programs – Homunculus represents movements, no individual muscles – In primates monosynaptic connection to α- motoneurons – No 1:1 transmission Motor Pathways Extrapyramidal system – Historical definition: all neuclei and tracts except the pyramidal system – Polysynaptic cortco- spinal projections – Cerebellum – Basal ganglia – Modulates spinal reflex arcs Usually inhibition Motor Pathways Upper motor neuron lesion – Paresis of movements – Minor atrophy – Initially flaccid (spinal shock) – Spasticity after some weeks – Increased reflexes – Pathological reflexes Lower motor neuron lesion – Paresis of muscles – Atrophy – Flaccid muscle tone – Loss of reflexes Motor Pathways Electrophysiological assessment – Bereitschaftspotenzial – Transcranial MEPs Electric stimulation Magnetic stimulation – Spinal magnetic stimulation – Motor nerve conduction – F-Waves – H-Reflex – EMG To be continued