Temporal Bone Studies of the Human Peripheral Vestibular System

Abstract

Scarpa's ganglion cell counts were performed in 106 serially sectioned, normal human temporal bones from 75 individuals. Of these 106 bones, 15 were from neonates less than 30 days old, 14 were from infants between the ages of 1 and 12 months, and the remainder were distributed throughout each decade of life, with sample sizes ranging from 4 to 10 per decade. All temporal bones had to meet 2 criteria: no symptoms or signs of inner ear disease except for presbycusis in the medical case history and no abnormality in the inner ear on light microscopy. The total ganglion cell counts declined significantly with age at an average rate of 57 cells per year. The age-related decline was significantly greater in the superior division than in the inferior division. There was also a significant sex effect, independent of age: for any age, the count in men averaged 1,526 cells higher than in women. There was no significant interaural difference. Mathematical models were developed to compute the mean and 95% prediction intervals for Scarpa's ganglion cell counts in terms of age and sex parameters. The counts and models will serve as a normative database against which to compare counts made in temporal bones from subjects with known vestibular disorders.

Age-Related Primary Cochlear Neuronal Degeneration in Human Temporal Bones

“…The technique used for SGC counts was that originally described by Schuknecht (Otte et al 1978) and used subsequently by others for the spiral and Scarpa's ganglia in human temporal bones (Velazquez-Villasenor et al 2000). All SGCs with nucleus and nucleolus were counted in each cochlear turn from every tenth section.…”

Age-Related Changes in Vestibular Evoked Myogenic Potentials

“…Several previous studies have demonstrated a decrease in VEMP amplitude with increasing age [Ochi and Ohashi, 2003;Su et al, 2004;Welgampola and Colebatch, 2001;Zapala and Brey, 2004]. The decrease in VEMP is not surprising considering that increasing age is related to loss of vestibular hair cells Rosenhall, 1973], vestibular nerve fibers [Bergstrom, 1973], vestibular ganglion cells [Richter, 1980;Velazquez-Villasenor et al, 2000] and vestibular brainstem neurons [Lopez et al, 1997;Tang et al, 2001]. Nevertheless, several previous studies have failed to reveal a large age-related decrease in vestibular function tests.…”

The Vestibular System: A Newly Identified Regulator of Bone Homeostasis Acting Through the Sympathetic Nervous System

“…Hair cells themselves can also undergo morphological changes with age, such as cilia disarrangement, increased cilia fragility, and development of giant cilia [95,96]. The neuronal structures relaying vestibular signals can be affected with time as well, as revealed by a decrease in Scarpa's ganglion cell number [97] and a decline in the number of primary neurons of the human vestibular system [98] in both aged humans and rats [99][100][101]. A prospective trial conducted with 70 healthy individuals traced a time-course of vestibular information integration and led to the conclusion that vestibular information reached a peak at the age of 40-49 years old and then decreased.…”