The Rôle of the Skull and Dura in Experimental Feline Hydrocephalus

Abstract

SUMMARY The skull and dura were removed over one or both cerebral hemispheres of cats with experimental hydrocephalus, and the effects on ventricular volume and csf turnover were measured by ventricular perfusion. This procedure frequently resulted in bilateral massive ventriculomegaly when the calvarium was removed on both sides; when it was removed on one side, ventriculomegaly occurred only on that side. No differences in rates of csf formation and absorption between both groups of animals were noted; however, these rates may be significantly different from those noted in hydrocephalic cats with intact skulls. RÉSUMÉ Le rôle du crâne et de la duremère dans l'hydrocéphalie expérimentale du chat Le crâne et la duremère ont été supprimés sur l'un ou les deux hémisphèes cérébraux de chat présentant une hydrocéphalie expérimentale; les effets sur les volumes ventricu‐laires et la circulation du lcr furent mesurés par perfusion ventriculaire. Ce procédé a provoqué fréquemment une ventriculomégalie massive bilatérale en cas de résection de la boite crânienne des deux côtés; en cas de résection unilatérale, la ventriculomégalie ne se manifestait que du même côté. Entre les deux groupes, il n'a été noté aucune différence dans les taux d'absorption ou de formation de lcr, mais ces taux pouvaient être signi‐ficativement différents de ceux observés chez les chats hydrocéphales à crâne intact. ZUSAMMFASSUNG Die Bedeutung von Schädeldach und Dura bei experimentellem Hydrocephalus bei Katzen Bei Katzen mit experimentellem Hydrocephalus wurden das Schädeldach und die Dura entfernt, und durch ventriculäre Perfusion wurde der Einfluß auf das ventriculäre Volumen und die Liquorzirkulation gemessen. Bei Entfernung des Schädeldaches auf beiden Seiten resultierte dadurch häufig eine doppelseitige massive Ventrikelvergrößerung; wenn es nur auf einer Seite entfernt worden war, trat die Ventrikelvergrösserung nur auf der Seite auf. Zwischen den beiden Gruppen wurden keine Unterschiede bei der Liquorbildung und Liquorabsorption beobachtet, aber es ist möglich, daß dafür signifikante Unterschiede bei hydrocephalen Katzen mit intaktem Schädeldach bestehen. RESUMEN El papel del cráneo y fa dura en el hidrocéfalo experimental del gato Se extirpó la parte ósea del cráneo y la dura sobre uno o dos hemisferios cerebrales de gatos con hidrocefalia experimental y se midió por perfusión ventricular los efectos sobre el volumen ventricular y el ciclo del lcr. Este proceder daba lugar frecuentemente a una ventriculomegalia masiva bilateral cuando se extirpaba el hueso en ambos lados; si se extirpaba en un solo lado la ventriculomegalia ocurría sólo en este lado. No se observó ninguna diferencia en la velocidad de formación y absorción del lcr de ambos grupos, pero estas velocidades pueden ser significativamente diferentes de las observadas en gatos hidrocéfalicos con cráneo intacto.

Post-Traumatic Hydrocephalus after Decompressive Craniectomy: An Underestimated Risk Factor

“…Such a relationship has been already described by Weiford and Gardner (Weiford and Gardner, 1949), who reported a case of cerebral herniation secondary to ventricular dilation after craniectomy for trauma. The possible occurrence of such a condition was experimentally demonstrated in cats by Hochwald and associates (Hochwald et al, 1972). The correlation seen between ventricular dilation and the opening of the intracranial system to the atmosphere is also curiously suggested by the case described by Kaufman and Miller (Kaufman and Miller, 1978), of a patient suffering from marked herniation of cerebral tissue through a large skull defect associated with ipsilateral lateral ventricle enlargement, which was treated by elastic bandages that were rewrapped several times a day until the 160 !25 <10 RA brain herniation was definitively controlled.…”

Growing Skull Fracture [GSF], a Hydrodynamic Perspective: An Original Article

“…An analysis of published cases of GSF reveals its relatively frequent association with an underlying poroencephalic cyst and, at times also with a dilated portion of the ipsilateral ventricle which is shifted towards the skull defect [9]. It has been demonstrated experimentally that the creation of a skull defect with a dural laceration, results in an increased distensibility of the brain tissue in that area [16,17]. Nevertheless, this change in the elastic properties of the brain tissue becomes manifest only when an additional force comes into play, such as an increased intraventricular pressure (as in hydrocephalus) or as a decreased regional tissue pressure (as it occurs when brain edema resolves or when a localized area of injured brain is reabsorbed).…”

Hidrocéfalo, es una complicación o una consecuencia de la craniectomía descompresiva?

“…From a different perspective, a number of investigators working on experimental hydrocephalus and attempting to elucidate the influence of brain coverings on its development, added to their studied animals craniectomies and durotomies. While these procedures by themselves caused no significant change in the ventricular size nor in the sagittal sinus pressure 4,6,7 , when those animals were submitted to a ventricular perfusion, to the determination of pressure volume index (PVI) or induced into experimental hydrocephalus, a significant reduction in the elastic properties of the brain parenchyma became evident, together with a significant increase in the ventricular distensibility, and a dramatic increase in the capacity of their ventricular system to accommodate added volume 4,6,19,20 . From all of the above, it becomes clear that a decompressive craniectomy with a duroplasty provides definite conditions that would promote the generation of hydrocephalus, without even considering potential additional factors, such as brain trauma, ischemia or other pathologies that could cause an increase in cerebral tissue or CSF osmolality and further exacerbate the proclivity for hydrocephalus.…”