Quantitative analysis of myelinic fibers in human laryngeal nerves according to age.

INTRODUCTION AND AIM To carry out a morphometric analysis of myelinic fibers in laryngeal nerves aiming to identify quantitative changes as a result of aging. STUDY DESIGN Clinical and experimental. MATERIAL AND METHOD A 1cm fragment was collected from the superior laryngeal nerves and recurrent laryngeal nerves taken from twelve male cadavers. The sample was divided into two groups: those aged below 60 years (Adult) and those aged 60 years or more (Elderly). The material was evaluated under light microscopy coupled with an image analysis system. RESULTS The total number of myelinic fibers from the superior laryngeal nerve was similar in both age groups; there was, however, a trend for a higher number of 1 microm fibers in the adult group (p=0.0744). The adult group had a higher total number of myelinic fibers in the recurrent laryngeal nerve (p=0.0006), and this difference was seen in fibers with diameters between 1-3 microm (p<0.007). The adult group had a higher total number of myelinic fibers in the laryngeal nerves (sum of superior laryngeal nerves and recurrent laryngeal nerves fibers) compared to the elderly group (p<0.0091). CONCLUSION The total number of myelinic fibers in laryngeal nerves is higher for the group aged below 60 years.