Pathophysiology of Hydrocephalus

Endoscopic Third Ventriculostomy in Children with Myelomeningocele: A Case Series

“…The development of hydrocephalus is related to the associated Chiari type II malformation [2]. MRI in these patients reveals a caudal descent of the cerebellar vermis, the 4th ventricle and the caudal brainstem through the foramen magnum into the spinal canal, commonly below the level of C2.…”

“…Following ETV, ICP may take several days to normalize postoperatively, due to the increased flow of CSF through the ETV [24], and the patient may present with signs and symptoms of intracranial hypertension for a period, whilst the brain adapts to the CSF taking a new route through the subarachnoid space towards the areas of reabsorption in the venous system [2]. Some authors have suggested that combining choroid plexus cauterization with ETV could be an appropriate therapeutic approach [25].…”

“…MRI in these patients reveals a caudal descent of the cerebellar vermis, the 4th ventricle and the caudal brainstem through the foramen magnum into the spinal canal, commonly below the level of C2. The caudal descent of the brainstem results in an increased resistance to CSF flow through the tentorial hiatus, and its downward displacement causes stenosis of the aqueduct of Silvius [2]. Obstruction of the foramen magnum leads to occlusion of the exit foramina of the 4th ventricle (Magendi and Luschka), which together with a small posterior fossa, results in an increase in pressure in the posterior fossa which in turn provokes an increased resistance to the reabsorption of CSF at the level of the venous sinuses, due to venous hypertension [9].…”

“…The incidence of hydrocephalus in MM at the time of birth is between 15 and 20%, but the incidence increases after closure of the defect to 80-90% [1]. The Chiari type II malformation characteristically accompanies MM and is related to the development of hydrocephalus, with a multitude of anatomical variants having been described in these patients [2] (fig. 1).…”