Recurrent laryngeal nerve histopathology in spastic dysphonia: a preliminary study.

Spastic dysphonia is a severe voice disorder ordinarily described as psychogenic. Organic-neurologic changes secondary to central or peripheral nervous system involvement have also been postulated and led recently to the surgical treatment of spastic dysphonia by unilateral section of the recurrent laryngeal nerve (RLN). This study reports the histologic findings from these resections of the RLN from patients with an average 9.5 years duration of spastic dysphonia. Thirty percent of the RLNs examined demonstrated significant abnormalities as compared to age-matched controls. Although no reactive changes were noted by light microscopy, groups of fibers which did not stain for myelin or axons were found in RLNs from patients with spastic dysphonia. A preliminary ultrastructural study of these areas in one RLN revealed sheets of unmyelinated axons. These findings suggest an organic basis for spastic dysphonia at least in some patients.