Pathology of the intrinsic muscles of the larynx.

The intrinsic muscles of the larynx were exposed in each of 54 normal larynges derived from the autopsy series of a general hospital and submitted to microscopic examination. Muscle fibre alterations were found in all the posterior cricocarytenoid muscles in patients from 13 years of age on wards. In about half of the patients these changes included necrosis of segments of muscle fibres and secondary cellular reactions to this. In two cases of chronic autonomic failure with multiple system atrophy the intrinsic laryngeal muscles were similarly examined. Both cases showed a marked gross and microscopic atrophy of the posterior cricoarytenoid muscles; there were also microscopic changes similar to those found in the normal population. The significance of the changes in the routine post-mortem larynges, the changes in the cases of chronic autonomic failure with multiple system atrophy and the relationship between the two are discussed.