Q 21 Most common site of Optic nerve injury
Q22. Le-forte fracture is for
A. Facial skeleton
B. Lower limb bone
C. Spinal injury
D. Pelvis fracture
Q23. Best predictor in the GCS
A. Eye opening
B. Motor response
C. Verbal response
Ans. 21 B
Ref. Clinical Neurophthalmology, 431
Most common site is bony optic canal (intra canalicular( followed by intracranial optic nerve. Next is intra orbital.
The diagram below shows the parts of optic nerve
Entry of central retinal artery
Lesions anterior to central retinal artery insertion : Vision loss + Abnormalities in retinal circulation
Lesions post to central retinal artery insertion : mostly visual field changes
Le fort classified these fractures on the basis of pattern he got by applying force on cadavers.
The question has been discussed here
23) B, Motor response
Motor score is the best predictor of neurological outcome.
The m component of the GCS, is not only linearly related to survival, but preserves almost all the predictive power of the GCS