November 15, 2018
A 48-year-old with a bilateral, frontal decompressive craniectomy after a postoperative hematoma, following an olfactory meningioma resection. One week later the patient showed a sudden neurological deterioration.
Paradoxical Cerebral Herniation
- Background
- Paradoxical cerebral herniation is a herniation towards the opposite direction of the craniectomy site.
- It is an underrecognized and potentially life-threatening complication of a craniectomy.
- It occurs when atmospheric and gravitational forces overhelm intracranial pressures, spontaneously or precipitated by a lumbar puncture or a CSF drainage. In this patient's case, the trigger event was the positional change of the patient.
- Clinical Presentation
- Symptoms: Focal neurological deficits, depressed level of consciousness, brainstem release signs and autonomic instability.
- Key Diagnostic Features
- The features seen in the CT and MRI are a sunken skin flap with herniation of the brain away from the craniectomy defect, causing subfalcine and transtentorial herniation, compression of the midbrain and effacement of the basal subarachnoid cisterns.
- The diagnosis of a paradoxical herniation should be considered when a neurological deterioration and a sunken skull defect is seen in a patient with a large craniectomy.
- Differential Diagnosis
- The principal differential diagnosis includes trephine syndrome or sunken skin flap syndrome, in which the meningogaleal complex is sunken in appearance and resting on the deformed underlying brain in patients with prior craniectomy and headache or other nonspecific neurological symptoms. This is distinguised from paradoxical herniation in that it does not involve mesodiencephalic herniation.
- External Brain Tamponade: Another possible complication post craniectomy which shows a bulging skin flap, with a subgaleal fluid collection that compresses the brain.
- Treatment
- Treatment of this entity is a surgical emergency.
- “Paradoxical” measures are needed to raise the ICP and counter the external pressure: supine or Tredelenburg position, hydration, clamping of CSF drainage, and epidural blood patch for patients with CSF leaks. Cranioplasty would be the definitive therapy.
- This entity cannot be managed with measures such as hyperventilation, hyperosmolar therapy, or CSF drainage, because these would exacerbate the problem.
