Flaccid dysarthria is caused by damage to nerves that emerge from the brainstem (cranial) or spinal cord and travel directly to muscles that are involved in speech production.
Spastic dysarthria is caused by damage to the primary voluntary motor pathways, which originate in the frontal lobes of the brain and descend to the brainstem and spinal cord.
Hyperkinetic dysarthria is generally caused by damage to nerve pathways and centers within the depths of the brain (subcortex) known as the basal ganglia.
The most common causes of spastic dysarthria include spastic cerebral palsy , multiple sclerosis , amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease), multiple strokes, and closed head...