98th Annual Meeting DOG 2000

K 98

Morphological studies of the optic canal under clinical points of view

A. Thale1, K. Jungmann2, F. Paulsen2, B. Tillmann2, R. Rochels1

Background: In some cases of closed head injuries after minor blunt trauma an amaurosis can occur. Our knowledge concerning the pathophysiological mechanisms of traumatic optic neuropathy is limited.

Purpose: The aim of this study is to analyze the morphology of the optic canal to understand the effect of mechanical forces in the optic canal and the consecutive injuries.

Methods: 41 canales optici from body donors were analyzed by light microscopical, polarization microscopical, immunohistochemical and scanning electron microscopical techniques.

Results: In the optic canal collagen fibrils of the dural sheath are organized in a scissor like pattern. Within this collagen network multiple vessels are integrated. Main component of extracellular-matrix is collagen type I. Dural sheath and pial sheath are connected by collagen bundles. Parallel to these bundles small vessels form anastomoses between dural and pial vessel system. In the arachnoidea no blood vessels can be detected by immunohistochemical techniques.

Discussion: In case of blunt closed head injury with consecutive amaurosis the following pathophysiological mechanism can be discussed based on our morphological findings:

  1. Squeezing and rupture of nutritive vessels by transduction of shearing forces via the collagen scissor like network.
  2. Atrophy by pressure of the optic nerve after injury of microvascularization followed by formation of microhematomas and reactive edema.
  3. Direct injury of axons of the optic nerve by shearing forces within the optic canal.

1Klinik für Ophthalmologie der Christian-Albrechts-Universität zu Kiel, Hegewischstr. 2; 24105 Kiel
2 Anatomisches Institut der Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40; 24098 Kiel