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| CORRESPONDENCE |
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| Year : 2014 | Volume
: 62
| Issue : 2 | Page : 236 |
Comment on: Paradoxical herniation caused by cerebrospinal fluid drainage after decompressive craniectomy
Prasad Krishnan, Rajaraman Kartikueyan
Department of Neurosurgery, National Neurosciences Centre, Peerless Hospital Complex, Kolkata, West Bengal, India
| Date of Web Publication | 14-May-2014 |
Correspondence Address:
Prasad Krishnan
Department of Neurosurgery, National Neurosciences Centre, Peerless Hospital Complex, Kolkata, West Bengal
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0028-3886.132455
How to cite this article:
Krishnan P, Kartikueyan R. Comment on: Paradoxical herniation caused by cerebrospinal fluid drainage after decompressive craniectomy. Neurol India 2014;62:236 |
Sir,
We read with interest the article "Paradoxical herniation caused by cerebrospinal fluid drainage after decompressive craniectomy" by Wang et al. [1] and commend the authors on highlighting this uncommon complication after decompressive craniectomy (DC). Though the term "paradoxical herniation" was first used by Schwab et al. in 1998, [2] there is no clarity on what is "paradoxical" about this herniation and we feel the term is redundant. Cerebral herniations always occur along a pressure gradient (from high to low and never the other way around) and the cases described in literature as "paradoxical" are no exception to this rule.
Firstly, the myth that intracranial hypotension is a prerequisite for paradoxical herniation is untenable as the mere presence of a DC does not mean that the intracranial pressure is normal or low (otherwise the entity of external cerebral herniation would not be encountered as is seen in the images given along with this case). Removal of cerebrospinal fluid (CSF) either by lumbar puncture or shunting eliminates the buoyancy that the CSF provides to the brain and allows the atmospheric pressure to act as an extra-axial lesion causing pressure on the brain.
Further, the innate tendency of the brain to resist inward deformation by the atmospheric pressure (elastance) is decreased after tissue loss, which must have happened after the initial surgery in this patient too. This may be an additional factor in facilitating the so-called "paradoxical herniation". Parenchymal injury has been described as a positive predictive factor for inward sinking of the scalp flap by Stiver. [3]
Finally, while the authors have succinctly enumerated the effective procedures in dealing with this condition such as Trendelenburg's position, blocking the CSF drain, and hydration, we would, in addition, also emphasize the role of an epidural blood patch in preventing continuing CSF leak from the spinal dura after lumbar puncture, a fact which has been stressed by other authors as well. [4],[5]
| » References | |  |
| 1. | Wang QP, Zhou ZM, You C. Paradoxical herniation caused by cerebrospinal fluid drainage after decompressive craniectomy. Neurol India 2014;62:79-80. 
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| 2. | Schwab S, Erbguth F, Aschoff A, Orberk E, Spranger M, Hacke W. "Paradoxical" herniation after decompressive trephining. Nervenarzt 1998;69:896-900.
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| 3. | Stiver SI. Complications of decompressive craniectomy for traumatic brain injury. Neurosurg Focus 2009;26:E7.
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| 4. | Muehlschlegel S, Voetsch B, Sorond FA. Emergent epidural blood patch: Lifesaving treatment of paradoxical herniation. Arch Neurol 2009;66:670-1.
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| 5. | Vilela MD. Delayed paradoxical herniation after a decompressive craniectomy: Case report. Surg Neurol 2008;69:293-6.
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