What type of voice disorder may be characterized by a lack of normal vocal fold movement?

The type of voice disorder characterized by a lack of normal vocal fold movement is neurogenic voice disorder. This category of voice disorders arises from neurological conditions that affect the muscles and nerves responsible for controlling voice production. Conditions such as vocal fold paralysis or spasmodic dysphonia exemplify neurogenic disorders, where there is a direct impact on the motor control of the vocal folds, resulting in abnormal movement patterns or a complete inability to move the vocal folds.

Neurogenic voice disorders can result from various causes, including stroke, traumatic brain injury, or degenerative diseases such as Parkinson's disease. The fundamental aspect of these disorders is that they stem from dysfunctions within the nervous system that directly impair the physiological functions necessary for normal voice production.

In contrast, functional voice disorders are typically attributed to misuse or overuse of the voice, rather than neurological impairments. Organic voice disorders are associated with structural changes in the vocal folds, such as nodules or polyps, which do not primarily involve the nervous system's control. Psychogenic voice disorders are rooted in psychological factors, often manifesting as discrepancies in voice without clear physical causes, but without the direct impact on muscular control seen in neurogenic disorders.