Morphometry and morphology of rostral cranial fossa in brachycephalic dogs - CT studies.

Hydrocephalus occurs more often in brachycephalic individuals of different species. Detailed analysis of rostral cranial fossa-region of cerebrospinal fluid outflow-is necessary to understand causes leading to hydrocephalus in specimens with shortened skull. The objective of the study was to determine morphology and morphometry of rostral cranial fossa in brachycephalic dogs. Skulls of 126 dogs of different breeds and morphotypes were examined using computed tomography. Linear and volumetric measurement in the region of rostral cranial fossa and skull base were made. In brachycephalic dogs there is shortening of rostral cranial fossa which is linked with the volume reduction of this region. There are differences in skull base shape between brachycephalic dogs and other morphotypes. Similarities between brachycephalic dogs and patients with craniosynostoses were noted.

Rostral cranial fossa as a site for cerebrospinal fluid drainage - volumetric studies in dog breeds of different size and morphotype.

BACKGROUND: Hydrocephalus is a multifactorial condition, whose aetiology is not fully understood. Congenital hydrocephalus frequently occurs in small and brachycephalic dog breeds. Although it is widely accepted that the cribriform plate located in the rostral cranial fossa (RCF) is a site of cerebrospinal fluid (CSF) drainage, the RCF has not been studied extensively. Literature reports indicate that a decreased caudal cranial fossa (CCF) volume in the course of the Chiari-like malformation may obstruct CSF circulation. We hypothesised that morphological diversity among different breeds in the volume of the RCF may affect CSF circulation. The aim of the study was to carry out a volumetric analysis of the RCF and the cranial cavity and to determine the ratio between them in dog breeds of different size and morphotype. We performed computed tomography (CT) morphometric analysis of the RCF compartment by obtaining volume measurements from the transverse and reformatted sagittal and dorsal planes. RESULTS: The rostral cranial fossa percentage - volume of the rostral cranial fossa/volume of cranial cavity × 100 (volRCF/volCC × 100) was lower in small and brachycephalic dog breeds than in the other dogs. CONCLUSIONS: A reduced RCF volume was detected in small and brachycephalic dog breeds, some of which are predisposed to congenital hydrocephalus. This may lead to overcrowding of brain parenchyma in the RCF and may impede CSF circulation. Our observations may be useful for future studies focusing on the causes and new therapies to treat conditions such as hydrocephalus and syringomyelia.

Feasibility and accuracy of new insertion technique of S1 transpedicular screw. Computed tomography-based morphometric analysis.

OBJECTIVE: To assess feasibility and accuracy of a new insertion technique of S1 transpedicular screw. SUMMARY OF BACKGROUND DATA: Transpedicular stabilization in the first sacral vertebra (S1) is a technically demanding surgical procedure with inherent risk of loosening of the implant. A modification of the technique was recently proposed, along with the analytical verification which was performed based on the available literature. In the study, we performed radiological assessment of screws inserted into the S1 using the classical and modified techniques. METHODS: The analysis was performed in two parts. The first part was performed on eight cadaver specimens after implantation of the screws. In the second part, we used computed tomography images of patients with degenerative disk disease with a superimposed representation of screws. The thickness of the posterior cortex adherent to the screws, screw trajectory and their position with regard to the spinal canal was measured. The area of posterior cortex in contact with the screws was also calculated. RESULTS: The contact length and area was found to be two times greater for screws introduced with the modified technique. The convergence angle was comparable between the techniques, despite the shift of entry point. There was no canal breach, although with the modified technique the screws passed closer to the spinal canal. CONCLUSIONS: The modified technique is considered safe. In this technique, the screws pass through a thicker portion of the posterior cortex compared to the classical technique that aims at improving the stability of the fixation.