Paradoxical brain herniation, also known as sinking skin flap syndrome (SSFS) or syndrome of the trephined, is a rare and potentially fatal complication of decompressive craniectomy.
Atmospheric pressure exceeding intracranial pressure at the craniectomy results in displacement of the brain across various intracranial boundaries. This may result in subfalcine and/or transtentorial herniation. It is often triggered by acute imbalance caused by CSF drainage or lumbar puncture.
May range from asymptomatic or mono symptomatic state to acute neurological deterioration.
Large craniectomy with marked concavity of the overlying skin flap causing mass effect and effacing the superficial sulci and cause buckling of the grey-white matter. It can cause paradoxical midline shift to the opposite side of the craniectomy.
Treatment and prognosis
This is a neurosurgical emergency and necessitates immediate intervention to prevent permanent damage:
- place patient in Trendelenburg position to correct the improper balance between atmospheric and intracranial pressure
- next steps aim at the correction of the underlying cause e.g. manipulating CSF drains, lumbar puncture sites
- consider cranioplasty
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