Ultrastructure changes of cochlea and cochlear nerve after maxillofacial blast wound

Hua YANG; Yinghui TAN; Zumeng YA; Zhongyu LI

ABSTRACT

BACKGROUND:

There have been reports about the cochlea injury after high-velocity projectile wounding. The effect on ultrastructure of cochlea after blast was still unclear.

OBJECTIVE:

To investigate ultrastructural changes of cochlea and cochlear nerve after maxillofacial blast wound.

DESIGN:

A randomized controlled observational trail with dogs as subjects.

SETTING:

Otolaryngeal Department and Maxillofacial Surgery Laboratory of the Third Military Medical University of Chinese PLA.MATERIALS The study was conducted from August 1995 through July 1997. The animal model in maxillofacial blast wound was established in Animal Center of Xinqiao Hospital of the Third Military Medical University of Chinese PLA. Specimens were treated in Maxillofacial Laboratory and observed in Electron Microscope Laboratory. Totally 15 dogs of either sex (weighting 9. 5 - 13.5 kg, mean 11.3 kg ) were randomly divided into three groups with 5 in each group. Two groups served as trauma groups 1 and 2 and the other group as control.

METHODS:

The maxillary and mandibular regions of 10 dogs in trauma groups were wounded by model 8 cardboard-shelled detonators to establish animal model of maxillofacial blast wound. At the 1st and 6th hour after trauma the wounds were examined and specimens of cochlea and cochlear nerve were dissected out for electron microscopic observation to study the ultrastructural changes. The specimens in the control group were treated the same way as those in the trauma groups except for blast injury.

RESULTS:

After wounded, the cochlea and cochlear nerve in the early period manifested cilia disorder, edema of the nerve and mitochondrial degeneration. At the 6th hour after trauma there were extensive degeneration in cochlea and cochlear nerve, cilia fallen off hair cells and dissolution of the structures in nerve sheath.

CONCLUSION:

The ultrastructural changes of cochlea and cochlear nerve are severed as a result of maxillofacial blast wound, but in early period the injury is reversible. So it is very important that early cure should be emphasized in treatment.