Chronic uncal herniation secondary to posterior fossa shunting: case report and literature review

Abstract

We conclude that a negative pressure gradient in the posterior fossa, relative to the supratentorial compartment, is the etiology of the chronic uncal herniation in our patient. Comparing the case reports in the literature with our case, we postulate that chronic uncal herniation is a complication of shunting of a posterior fossa fluid cavity in children, many of them with Dandy-Walker syndrome and/or other cerebellar cystic formations. The treatment priority at presentation should be to rule out shunt malfunction. In the event of association with clinical over-drainage syndrome, there may be a role for changing the shunt system into a more conservative drainage combination.

Ascending Transaqueductal Cystoventriculoperitoneal Shunting in Dandy-Walker Malformation: Technical Note

“…It is known that the continuous drainage of CSF by posterior fossa shunting results in a chronic negative pressure gradient between the supra- and infratentorial compartments and may cause chronic uncal herniation [20]. As in our case, upward herniation of the posterior fossa contents may also occur.…”

“…However, aqueductal obstruction without stenosis may develop secondary to upward herniation of the posterior fossa cyst or the cerebellum [11,12,13]. Another reason for supratentorial ventricular dilatation is the blockage of the tentorial hiatus by bilateral uncal herniation due to the chronic negative pressure gradient between the supra- and infratentorial compartments [20]. Therefore, additional VP shunting is frequently necessary in CPS cases.…”

Descending transtentorial herniation, a rare complication of the treatment of trapped fourth ventricle: case report

“…26 Another condition that eventually shares the same pathogenesis is paradoxical herniation, which is a peculiar form of DTH resulting from intracranial hypotension secondary to lumbar CSF drainage in the absence of protective bone, as occurs during a craniotomy or after decompressive craniectomy. 16,18 Differently from our case, paradoxical herniation occurs in an unpartitioned and contiguous compartment.…”

Central brain herniation in Dandy–Walker syndrome

“…I conclude that a negative pressure gradient between the posterior fossa and supratentorium, secondary to shunt, is an essential component for the phenomenon to generate the respective force vector and its subsequent herniation [6].…”

“…2. In the event of association with clinical over-drainage syndrome, there may be a role for changing the shunt system into a more conservative drainage combination [6] or double and simultaneous shunting en-Yof a lateral ventricle and the posterior fossa cyst [4].…”