Update: Paradoxical herniation

Paradoxical herniation has been referred to as the herniation of a brain that has been decompressed surgically, without any extra-axial lesion that could account for the herniation 1) 2).

It is known as a rare complication of lumbar puncture in patients with decompressive craniectomy.
Although rare, paradoxical herniation in the setting of a large craniectomy defect may occur in the absence of cerebrospinal fluid drainage 3).
This entity should be suspected whenever transtentorial herniation occurs in conjunction with direct or indirect signs of intracranial hypotension. Placing the patient in the Trendelenburg position should be attempted, because this simple maneuver may turn out to be life-saving 4).
Those treatments for lowering ICP, such as mannitol, CSF drainage, and hyperventilation, all of which follows the Monro-Kellie doctrine will exacerbate paradoxical herniation, because lowering intracranial pressure increases the pressure gradient across the craniectomy defect 5).
This phenomenon is related to the negative gradient between atmospheric and intracranial pressures, which can be exacerbated by an upright posture, CSF leakage, or dehydration 6).
Patients who have undergone CSF drainage, such as, external ventriculostomy, ventriculoperitoneal shunt placement, or lumbar puncture are more susceptible to this phenomenon, for these conditions can lower ICP states relatively than that of extra-cranial pressures. In these situations, the brain is sucked down through the tentorial incisural notch essentially and the foramen magnum potentially 7).
Not surprisingly, the pressure acting over the cerebral cortex may cause neurological deficits. Several authors have claimed that skull defects may create a siphon effect on CSF dynamics, which distorts the dura, underlying cerebral cortex, and venous return, due to scarring and direct pressure to the brain 8) 9).

Clinical features

Symptoms may include focal deficits, brainstem release signs, autonomic instability, changes in level of consciousness, and pupil changes 10) 11).

Case reports

A 38-year-old man underwent decompressive craniectomy for severe brain swelling. He remained neurologically stable for five weeks, but then showed mental deterioration right after a lumbar puncture which was performed to rule out meningitis. A brain computed tomographic scan revealed a marked midline shift. The patient responded to the Trendelenburg position and intravenous fluids, and he achieved full neurologic recovery after successive cranioplasty 12).
A 56-year-old woman with no interesting medical history, who, after an olfactory groove meningioma surgery, presented a haemorrhage located in the surgical area with an important oedema. The patient required a second emergency surgery without any chance of conserving the cranial vault. During the post-operational period, great neurological deterioration in orthostatic position was noticed, which resolved spontaneously in decubitus. This deficit was resolved with bone replacement afterwards 13)
1) Oyelese AA, Steinberg GK, Huhn SL, Wijman CA. Paradoxical cerebral herniation secondary to lumbar puncture after decompressive craniectomy for a large space-occupying hemispheric stroke : case report. Neurosurgery. 2005;57:E594. discussion E594.
2) Vilela MD. Delayed paradoxical herniation after a decompressive craniectomy : case report. Surg Neurol. 2008;69:293–296. discussion 296.
3) , 6) Fields JD, Lansberg MG, Skirboll SL, Kurien PA, Wijman CA. “Paradoxical” transtentorial herniation due to CSF drainage in the presence of a hemicraniectomy. Neurology. 2006 Oct 24;67(8):1513-4. PubMed PMID: 17060591.
4) Rahme R, Bojanowski MW. Overt cerebrospinal fluid drainage is not a sine qua non for paradoxical herniation after decompressive craniectomy: case report. Neurosurgery. 2010 Jul;67(1):214-5; discussion 215. doi: 10.1227/01.NEU.0000370015.94386.1F. PubMed PMID: 20559071.
5) , 7) Liao CC, Kao MC. Cranioplasty for patients with severe depressed skull bone defect after cerebrospinal fluid shunting. J Clin Neurosci. 2002;9:553–555.
8) Ban SP, Son YJ, Yang HJ, Chung YS, Lee SH, Han DH. Analysis of complications following decompressive craniectomy for traumatic brain injury. J Korean Neurosurg Soc. 2010;48:244–250.
9) Sakamoto S, Eguchi K, Kiura Y, Arita K, Kurisu K. CT perfusion imaging in the syndrome of the sinking skin flap before and after cranioplasty. Clin Neurol Neurosurg. 2006;108:583–585.
10) Cho H, Kim CH, Kim JH, Kim JM. Paradoxical Herniation after decompressive craniectomy for acute subdural hematoma. J Korean Neurosurg Soc. 2006;40:51–53.
11) Fields JD, Lansberg MG, Skirboll SL, Kurien PA, Wijman CA. “Paradoxical” transtentorial herniation due to CSF drainage in the presence of a hemicraniectomy. Neurology. 2006;67:1513–1514.
12) Jung HJ, Kim DM, Kim SW. Paradoxical transtentorial herniation caused by lumbar puncture after decompressive craniectomy. J Korean Neurosurg Soc. 2012 Feb;51(2):102-4. doi: 10.3340/jkns.2012.51.2.102. Epub 2012 Feb 29. PubMed PMID: 22500203; PubMed Central PMCID: PMC3322205.
13) Narro-Donate JM, Huete-Allut A, Escribano-Mesa JA, Rodríguez-Martínez V, Contreras-Jiménez A, Masegosa-González J. [Paradoxical transtentorial herniation, extreme trephined syndrome sign: A case report.]. Neurocirugia (Astur). 2014 Nov 11. pii: S1130-1473(14)00141-9. doi: 10.1016/j.neucir.2014.09.006. [Epub ahead of print] Spanish. PubMed PMID: 25455761.

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