These include disorders such as Parkinson's disease which can cause weakening of the voice and swallowing, voice tremor, and spasmodic dysphonia.
Spasmodic dysphonia is a movement disorder affecting the voice and characterized by involuntary spasms which disrupt phonation. It may also be accompanied by tremor, hoarseness, strain, and pitch breaks. It is considered a dystonia, or movement disorder specific to the vocal folds, similar to other dystonias such as tortocollis or blepharospasms (rapid eye-blinking movements). The treatment for spasmodic dysphonia may involve the use of Botox injections into the muscles of the vocal folds. Botox helps to weaken the spasms.