Hypothyroidism and hyperthyroidism are common medical disorders that are often accompanied by diverse types of neurologic and neuromuscular dysfunction. Although some of these associated disorders are well known to physicians, others are not. All of these neurologic manifestations are important because they can severe as important clues to the diagnosis of a thyroid disorder. Furthermore, they are often related to the patients' presenting complaints. In addition, much like other manifestations of thyroid dysfunction, they are often reversible with return of the patient to the euthyroid state.