motor speech disorder caused by damage to lower motor neurons (cranial or spinal nerves) or their connections with the muscles that provide speech. It is characterized by weakness, hypotonia (reduced muscle tone) and decreased reflexes in the affected muscles, which leads to indistinct articulation, hypernasality, aspirated voice and decreased speech volume. Possible causes include a brainstem stroke, neuromuscular diseases (such as myasthenia gravis), tumors, or injuries.