MRI Assessment of Dogs with Descending Trans-tentorial and/or Foramen Magnum Brain Herniations.
Barker J.R. and Faissler D.
Conference Proceedings, (2012). American College of Veterinary Internal Medicine, New Orleans:
The aim of this study was to develop a scoring system of MRI images assessing backwards movement of the brain in the caudal fossa caused by supratentorial space occupying lesions. A semi-quantitative approach determining CSF filling in eight regions, and a quantitative measurement of four different parameters were designed. MRI images were examined for lesion location and lateralization. Total brain and lesion volume, surrounding edema, and relative volume of the mass were calculated. Clinical signs were grouped into seizure, abnormal cranial nerve function, cranial nerve dysfunction combined with abnormal gait and endocrine disease. Pairwise data analysis was per- formed comparing affected with unaffected dogs using the SPSS 19 software package 81 affected and 81 control dogs were analyzed. Sex and breed distribution were similar in both groups. All semi-quantitative and the quantitative parameters of tentorial angle, foramen magnum line and brainstem ratio showed a significant difference between study and control dogs. Tentorial angle, cerebellar height, length, their ratio, spinal cord height and brainstem to spinal cord ratio were significantly correlated to the degree of CSF filling. Lesions in the frontal or olfactory lobes caused significantly less herniation when compared to masses in other brain areas. Total and relative lesion volumes were significantly correlated to all semi-quantitative measurements, tentorial angle and cerebellar length. In conclusion, our semi-quantitative measurements and tentorial angle best determine the magnitude of brain herniation. The ratio of lesion and edema volume to brain volume can predict degree of herniation best when used in conjunction with lesion location.