Pathophysiologie der Restitution zentralmotorischer Störungen

Zusammenfassung

Die meisten Bewegungen werden durch motorische kortikale Areale gesteuert, die partielle Redundanz aufweisen und über mehrere Gefäßterritorien verteilt sind. Bei Läsion der dominierenden kortikospinalen Projektion vom primär motorischen Kortex (M1) können die noch intakten motorischen Repräsentationen ihre Rolle ändern, sofern der Patient eine Strategie findet, sie zu aktivieren. Somit hängt die Prognose der motorischen Restitution ab von Lokalisation und Ausdehnung einer zentralen Läsion sowie von der Intensität und Repetition des Trainings.

Neben den Neuronen des Kortikospinaltrakts tragen auch kortikostriale Projektionen zur Restitution bei. Cues wie sensorisches Feedback, propriozeptive, verbale und visuelle Reize oder bereits die Vorstellung einer Bewegung können über dieses System die Aktivität der Motoneurone steigern sowie den Abruf erlernter Bewegungsmuster erleichtern.

Bei Läsion des Kortikospinaltrakts werden motorische Systeme des Mittelhirns aktiviert, beispielsweise der an der Steuerung der Lokomotion beteiligte pedunculopontine Nucleus. Dieser projiziert auch zu den Retikulo-und Rubrospinaltrakten, die eine qualitativ eingeschränkte motorische Erholung ermöglichen. Die Systeme des Mittelhirns sind auch mit central pattern generators des Rückenmarks verbunden, die neben ihrer Rolle für das Gehen auch an synergistischen Bewegungen der oberen Extremität beteiligt sein könnten. Spastische Syndrome treten vorwiegend nach nahezu kompletter zentraler Deefferenzierung mit Plegien auf. Durch ein intensives Training werden sie nicht wesentlich verstärkt, sofern eine inkomplette Parese mit verbleibender motorischer Funktion vorliegt.

Summary

Most types of movements are controlled by multiple motor cortical areas that are distributed amongst several vascular territories and provide partial redundancies of functions. The function of surviving motor circuits can undergo changes after a lesion of the dominant corticospinal projection from the primary motor cortex (M1) if the patients find a strategy to activate them. Intensity of training and location or extent of the lesions are crucial factors of motor outcome.

Corticostriatale neurons add to the role of the corticospinal tract for restitution. The activity of motor neurons can be enhanced via corticostriatale circuits by sensory feedback, proprioceptive, verbal or visual cues, or even by pure imagination of the movement. Such cues may also facilitate the recall of pre-learned movement patterns.

In case of lesions to the corticospinal tract independent motor systems of the mesencephalon might be activated, e.g. the pedunculopontine nucleus which is involved in the control of locomotion. Their projections via the reticulospinal and rubrospinal tracts allow for partial recovery although the quality of movements remains limited. The mesencephalic motor system also projects to central pattern generators of the spinal cord which are known for their function in locomotion. However, the spinal pattern generators may also have a role for synergistic movements of the upper extremity. Spasticity is mostly evoked only by virtually complete central de-efferentation with plegia. Even intense exercise in partial paresis with remaining motor function does not lead to worsened spasticity in the majority of cases.

Schlüsselwörter

Motorische Restitution - Feinmotorik - Rehabilitation - Schlaganfall

Keywords

Motor restitution - fine motor functions - rehabilitation - stroke

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