Paradoxical Brain Herniation after Cranioplasty: Secondary Sunken Flap Syndrome

Abstract

Decompressive craniectomy is a life-saving procedure done for innumerable etiologies. Though, not a technically demanding procedure, it has its own complications. Among many, sinking flap syndrome or syndrome of the trephined or paradoxical herniation of brain is frequently underestimated. It results from the pressure difference between the atmospheric pressure and the intracranial pressure causing the brain to shift inward at the craniectomy site. This can present with either nonspecific symptoms leading to delay in diagnosis or acute neurological deterioration, memory disturbances, weakness, confusion, lethargy, and sometimes death if not treated. Cranioplasty is a time validated procedure used to treat paradoxical brain herniation with good and early neurological recovery. We, here in, are going to describe a case report in which the paradoxical herniation occurred after cranioplasty which has not been described in literature.

Paradoxical Brain Herniation: An Unexpected Diagnosis

“…Paradoxical brain herniation is an entity frequently underestimated and substantially underreported, with only a few case reports published in the literature. It is designated as “paradoxical” since it encompasses two paradoxical phenomena, there is a herniation of the decompressed side of the brain, contralateral to the cranial defect, and the treatment itself as it is exactly the opposite of the standard treatment approach applied to the vast majority of brain herniations [ 7 ].…”

“…While the main pathophysiologic mechanism is a direct transmission of atmospheric pressure to intracranial cavity, other features may also contribute to the clinical scenario, including decrease in cerebral blood flow resulting from microarterial circulation impairment, brain compression, and decrease in CSF pressure. This herniation pattern is more evident and susceptible for deterioration when there is a contribution for a ventricular collapse and alteration of the Monro-Kellie law, for instance after procedures involving CSF drainage, including a CSF leakage, ventricular shunt, or lumbar puncture in the postoperative period [ 4 , 7 - 9 ]. Indeed, in a patient with a major cranial defect, the CSF pressure in the lumbar region on a vertical position is greater than that in a patient with an intact cranial vault.…”

“…Notwithstanding, cranioplasty is the validated and definitive procedure for the treatment of paradoxical brain herniation with early and complete neurological recovery [ 10 ]. It has been shown that after the cranioplasty, the lumbar CSF pressure returned to its normal levels [ 7 ].…”

“…[ 1 - 2 , 4 ]. As a result, among potential complications, a mesodiencephalic herniation syndrome, termed paradoxical herniation of brain, is frequently unrecognized and underreported [ 7 ]. We present the case of a 48-year-old woman with a diagnosis of paradoxical brain herniation that developed in the first week post-neurosurgical intervention, earlier than previously reported in the literature (most commonly it develops one month following surgical intervention).…”