Observation of neural electrophysiology and morphology in traumatic optic neuropathy in cat model / 中华耳鼻咽喉头颈外科杂志

ABSTRACT

<p><b>OBJECTIVE</b>To establish the animal model of traumatic optic neuropathy similar to clinical feature by injuring the optic nerve of the pipeline through the ethmoid and sphenoid sinus. The electrophysiology and morphology were observed.</p><p><b>METHODS</b>The optic nerve in 2 cats was anatomically observed. Thirty healthy adult cats were divided into 1 h, 1 d, 3 d, 1 w, 2 w, 4 w injury groups. The right eye was selected as the experiment eye, and the left as the control. The optic canals were damaged by the injury instrument. The changes of optic nerve were observed using light and electron microscope. The pattern reversal visual evoked potential (PR-VEP) was used to determine the succeed model and pupil was monitored. PR-VEP and neural tissue morphology were examined at intervals of 1 h, 1 d, 3 d, 1 w, 2 w, 4 w after trauma.</p><p><b>RESULTS</b>Eight cats had Marcus-Gunn's pupil, and 22 cats did not have after injury. Neural tissue was physaliphorous degeneration in light microscope. The neural fibers swelled gradually and fibers physaliphorous degeneration in the first day after damage. At the seventh day, the bubble enlarged to be a big flat. After two weeks, the big flat bubble came out to be a bigger bubble. Under the electronic microscope, axons were physaliphorous degeneration, crack emerged between axon membrane and myelin sheath and myelin sheath were loose in the first day. At the third day, axon swelled, physaliphorous degeneration rose and myelin sheath were loose obviously. At the seventh day, axon and myelin sheath appeared loop in half cycle and bubble-like broke up. A lot of pieces came out and axon became physaliphorous and uniform. Microtubule and microfilament disappeared. After two weeks, myelin sheath became onion-like. On fourth week, myelin sheaths enlarged and squeezed to center. Axoplasm disappeared and neural tissues collapsed.</p><p><b>CONCLUSIONS</b>This animal model was similar to clinical optic nerve decompression through ethmoid and sphenoid sinus. The change of PR-VEP and neuromorphology were distinct before and after trauma. The pathological changes of optic nerve catching vibrated injury are mainly degeneration, so earlier decompression of optic nerve may improve the visual function.</p>