Trauma-induced hearing loss due to apoptotic auditory neuronal death in cerebellopontine angle manipulations: an experimental study

Abstract

This study reports for the first time the appearance, extent and duration of auditory neuron apoptosis following injury to the central processes. Apoptosis was studied in a rat model that consisted of compression of the auditory nerve in the cerebellopontine angle cistern with intraoperative recordings of auditory nerve compound action potentials to ensure highly reproducible results. Rats were killed between days 0 and 14 after compression, and apoptosis of spiral ganglion cells (SGCs) was evaluated quantitatively and qualitatively. The average number of TUNEL-positive apoptotic SGCs in each cochlear turn increased from days 1 to 5, and then decreased gradually to an undetectable level on day 14 after compression. The average proportion of apoptotic SGCs identified in any cochlear turn on any day was always lower than 10%. These results of our present study should be useful in determining the therapeutic time window for rescuing auditory neurons undergoing apoptosis due to injury during surgery in the cerebellopontine angle.