Motor Speech Disorders: Clues to Neurologic Diagnosis

Speech is the most complex of innately acquired human motor skills, an activity characterized in normal adults by the production of about 14 distinguishable sounds per second through the coordinated actions of about 100 muscles innervated by multiple cranial and spinal nerves. The ease with which we speak belies the complexity of the act, and that complexity may help explain why speech can be exquisitely sensitive to nervous system disease. In fact, changes in speech can be the only evidence of neurologic disease early in its evolution and sometimes the only significant impairment in a progressive or chronic neurologic condition. In such contexts, recognizing the meaning of specific speech signs and symptoms can provide important clues about the underlying pathophysiology and localization of neurologic disease.