|LETTERS TO EDITOR
|Year : 2017 | Volume
| Issue : 3 | Page : 291-293
“Formation” of Chiari “malformation:” Nature's philosophical way of adaptation
Department of Neurosurgery, Bangabandhu Sheikh Mujib Medical University, Dhaka 1000, Bangladesh
|Date of Web Publication||20-Sep-2017|
Department of Neurosurgery, Bangabandhu Sheikh Mujib Medical University, Dhaka 1000
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Rahman A. “Formation” of Chiari “malformation:” Nature's philosophical way of adaptation. J Craniovert Jun Spine 2017;8:291-3
|How to cite this URL:|
Rahman A. “Formation” of Chiari “malformation:” Nature's philosophical way of adaptation. J Craniovert Jun Spine [serial online] 2017 [cited 2018 Aug 17];8:291-3. Available from: http://www.jcvjs.com/text.asp?2017/8/3/291/215216
It is always very invigorating and captivating to go through Professor Goel's writings as those are filled with new philosophical visions and great food for thought. In the last issue of the Journal of Craniovertebral Junction and Spine, the editorial entitled “Is Chiari a “formation” or a “malformation?” by him has made me very fascinated. Professor Goel, an authority on the craniovertebral junction (CVJ), really understands the complex anatomy, physiology, and pathology, from his vast experience in management of the pathologies of this region with pioneering philosophy, and can explain it simply. The blending of science with nature is clean and tidy, and anyone can understand it effortlessly with a deeper thought.
He is philosophizing for quite some time now that the Chiari malformation is actually a nature's reaction to normalize the physiology of the neural structures in response to abnormality in the CVJ in the form of atlantoaxial instability., This is where we have different visions and we discussed concerning this concept earlier, for some obvious reasons. We agree very much with his interpretation that short neck, torticollis, Klippel–Feil abnormality, assimilation of atlas, C2–C3 fusion, and platybasia are nature's attempt to shorten the entire spine length vertically, as well as there is the longer–thinner brain stem–spinal cord to compensate stretching against bony abnormalities, which are quite logical and rational explanation concerning nature's adaptation. In Chiari malformation, the tonsils are herniated and compress the brain stem and the spinal cord around the foramen magnum. Professor Goel advocates that the tonsils act as the “natural protective cushion” for the neural structures around the foramen magnum from compression by the indentation of odontoid process. This might be true for the cases of Chiari with simultaneous basilar invaginations. However, this does not stand for the cases where there is no basilar invagination associated with Chiari as there is no indentation on the brain stem or spinal cord by the odontoid. If the tonsillar herniation would have been the real protective mechanism of nature, there should have been no features of compression on the brain stem or the spinal cord, which is vividly evident when these structures are surrounded and guarded by the natural protection of cerebrospinal fluid (CSF) without tonsillar herniation in normal persons. On the contrary, the features tend to wane, when the compression is relieved by posterior fossa decompression with or without duraplasty in Chiari patients. Moreover, as he says that “water” or “neuroaqua” in different forms in different parts of the neural structures provides motherly protective properties by increasing its presence inside (syringomyelia) and/or outside the spinal cord (external syrinx), it does not fit with the protective physiognomies of the nature. This is arguable because the neuroaqua in the form of CSF is displaced around the foramen magnum in Chiari malformation by the herniated tonsil, rather than to rush in there, in rescue of the delicate neural structures and fails to protect these from compression. In addition, the changes in CSF dynamics between the cranial and spinal compartments due to blockage of CSF flow by the herniated tonsil leading to discrepancy in pulsatile flow of CSF are postulated to be the reason of development of syrinx to further jeopardize the situation., The neuroaqua inside the spinal cord or brain stem, manifested as syringomyelia and syringobulbia, compresses from within, rather than to protect it. Thus, the spinal cord and the brain stem in Chiari are strangled by the three-pronged attack – externally by bone anteriorly, when there is associated basilar invagination, by the herniated tonsil posteriorly, and by the syrinx within.
The basic pathology of Chiari is the malformation of the posterior fossa which renders it to be shallow to expel out the contents that are not accommodated in the less capacious than usual posterior fossa.,,, The pathology of this anomaly is in the anomalous formation of the occipital enchondrium, causing overcrowding and herniation of parts of the hindbrain, a well-documented fact from the study by Nishikawa et al. The nature's role here may be the displacement of comparatively less vital structure like the tonsils that the nature has placed strategically to be relocated first and easily when in need, as in Chiari. Moreover, this seems to be a nature's “divine intervention” to compensate the anomaly. Hence, we feel that Chiari is not a formation, rather actually a malformation, where the tonsillar herniation and other changes are the formations that might act as damage control strategy of the nature. Although the effect of this damage control technique is not very apparent always, and sometimes these seem to be rather havoc to the patient, these may be an attempt of nature to halt or at least delay the progression of impairment.
Professor Goel, in this editorial, defined anomaly and alteration as: “an anomaly is a change or a deviation from the norm it is a peculiarity that does not fit in” and “an alteration is a change that is performed to make a fitting or appearance of an object,” respectively. By these definitions, the shallow posterior fossa is the “deviation” from the normal posterior fossa that fails to contain the natural neural contents of this container devised by the nature. Hence, this “peculiarity” is surely an anomaly. On the other hand, herniation of the tonsil and other contents are the “alterations” that the nature has performed to make a fitting for the structures that are jeopardized by the anomalous making of the posterior fossa. The sequences that follow this anomaly are the nature's attempt to alter the arrangements of the structures around the CVJ in an effort to recompense this anomaly. Thus, the Chiari remains to be the anomaly, while the changes it brings to “maintain sanctity to the neural structures” are the alterations of nature.
Nevertheless, this editorial by Professor Goel is a brainstorming one. Even with differences in our opinion, I really admire Professor Goel for his new viewpoint, which will make us rethink about the management of patients with Chiari malformation. No doubt that, this thought is definitely a laudable one which possibly will provide new vision in management of this complex clinical entity in the future.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Goel A. Is Chiari a “formation” or a “malformation?” J Craniovertebr Junction Spine 2017;8:1-2.
Goel A. Is atlantoaxial instability the cause of Chiari malformation? Outcome analysis of 65 patients treated by atlantoaxial fixation. J Neurosurg Spine 2015;22:116-27.
Goel A. Is Chiari malformation nature's protective “air-bag”? Is its presence diagnostic of atlantoaxial instability? J Craniovertebr Junction Spine 2014;5:107-9.
Rahman A. Does atlantoaxial dislocation really cause Chiari? J Neurosurg Spine 2015;23:393.
Kothari M, Goel A. 'Aqualisation' of neuraxis: Wondrous neuraqua CSF. Neurol India 2008;56:1-3.
] [Full text]
Buell TJ, Heiss JD, Oldfield EH. Pathogenesis and cerebrospinal fluid hydrodynamics of the Chiari I malformation. Neurosurg Clin N
Koyanagi I, Houkin K. Pathogenesis of syringomyelia associated with Chiari type 1 malformation: Review of evidences and proposal of a new hypothesis. Neurosurg Rev 2010;33:271-84.
Yan H, Han X, Jin M, Liu Z, Xie D, Sha S, et al.
Morphometric features of posterior cranial fossa are different between Chiari I malformation with and without syringomyelia. Eur Spine J 2016;25:2202-9.
Stovner LJ, Bergan U, Nilsen G, Sjaastad O. Posterior cranial fossa dimensions in the Chiari I malformation: Relation to pathogenesis and clinical presentation. Neuroradiology 1993;35:113-8.
Karagöz F, Izgi N, Kapíjcíjoglu Sencer S. Morphometric measurements of the cranium in patients with Chiari type I malformation and comparison with the normal population. Acta Neurochir (Wien) 2002;144:165-71.
Furtado SV, Thakre DJ, Venkatesh PK, Reddy K, Hegde AS. Morphometric analysis of foramen magnum dimensions and intracranial volume in pediatric Chiari I malformation. Acta Neurochir (Wien) 2010;152:221-7.
Nishikawa M, Sakamoto H, Hakuba A, Nakanishi N, Inoue Y. Pathogenesis of Chiari malformation: A morphometric study of the posterior cranial fossa. J Neurosurg 1997;86:40-7.