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Pathogenesis of Chiari malformation: a morphometric study of the posterior cranial fossa.
J Neurosurg. 1997 Jan; 86(1):40-7.JN

Abstract

To investigate overcrowding in the posterior cranial fossa as the pathogenesis of adult-type Chiari malformation, the authors studied the morphology of the brainstem and cerebellum within the posterior cranial fossa (neural structures consisting of the midbrain, pons, cerebellum, and medulla oblongata) as well as the base of the skull while taking into consideration their embryological development. Thirty patients with Chiari malformation and 50 normal control subjects were prospectively studied using neuroimaging. To estimate overcrowding, the authors used a "volume ratio" in which volume of the posterior fossa brain (consisting of the midbrain, pons, cerebellum, and medulla oblongata within the posterior cranial fossa) was placed in a ratio with the volume of the posterior fossa cranium encircled by bony and tentorial structures. Compared to the control group, in the Chiari group there was a significantly larger volume ratio, the two occipital enchondral parts (the exocciput and supraocciput) were significantly smaller, and the tentorium was pronouncedly steeper. There was no significant difference in the posterior fossa brain volume or in the axial lengths of the hindbrain (the brainstem and cerebellum). In six patients with basilar invagination the medulla oblongata was herniated, all three occipital enchondral parts (the basiocciput, exocciput, and supraocciput) were significantly smaller than in the control group, and the volume ratio was significantly larger than that in the Chiari group without basilar invagination. These results suggest that in adult-type Chiari malformation an underdeveloped occipital bone, possibly due to underdevelopment of the occipital somite originating from the paraxial mesoderm, induces overcrowding in the posterior cranial fossa, which contains the normally developed hindbrain. Basilar invagination is associated with a more severe downward herniation of the hindbrain due to the more severely underdeveloped occipital enchondrium, which further exacerbates overcrowding of the posterior cranial fossa.

Authors+Show Affiliations

Department of Neurosurgery, Osaka City University Medical School, Japan.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Controlled Clinical Trial
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

8988080

Citation

Nishikawa, M, et al. "Pathogenesis of Chiari Malformation: a Morphometric Study of the Posterior Cranial Fossa." Journal of Neurosurgery, vol. 86, no. 1, 1997, pp. 40-7.
Nishikawa M, Sakamoto H, Hakuba A, et al. Pathogenesis of Chiari malformation: a morphometric study of the posterior cranial fossa. J Neurosurg. 1997;86(1):40-7.
Nishikawa, M., Sakamoto, H., Hakuba, A., Nakanishi, N., & Inoue, Y. (1997). Pathogenesis of Chiari malformation: a morphometric study of the posterior cranial fossa. Journal of Neurosurgery, 86(1), 40-7.
Nishikawa M, et al. Pathogenesis of Chiari Malformation: a Morphometric Study of the Posterior Cranial Fossa. J Neurosurg. 1997;86(1):40-7. PubMed PMID: 8988080.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Pathogenesis of Chiari malformation: a morphometric study of the posterior cranial fossa. AU - Nishikawa,M, AU - Sakamoto,H, AU - Hakuba,A, AU - Nakanishi,N, AU - Inoue,Y, PY - 1997/1/1/pubmed PY - 1997/1/1/medline PY - 1997/1/1/entrez SP - 40 EP - 7 JF - Journal of neurosurgery JO - J Neurosurg VL - 86 IS - 1 N2 - To investigate overcrowding in the posterior cranial fossa as the pathogenesis of adult-type Chiari malformation, the authors studied the morphology of the brainstem and cerebellum within the posterior cranial fossa (neural structures consisting of the midbrain, pons, cerebellum, and medulla oblongata) as well as the base of the skull while taking into consideration their embryological development. Thirty patients with Chiari malformation and 50 normal control subjects were prospectively studied using neuroimaging. To estimate overcrowding, the authors used a "volume ratio" in which volume of the posterior fossa brain (consisting of the midbrain, pons, cerebellum, and medulla oblongata within the posterior cranial fossa) was placed in a ratio with the volume of the posterior fossa cranium encircled by bony and tentorial structures. Compared to the control group, in the Chiari group there was a significantly larger volume ratio, the two occipital enchondral parts (the exocciput and supraocciput) were significantly smaller, and the tentorium was pronouncedly steeper. There was no significant difference in the posterior fossa brain volume or in the axial lengths of the hindbrain (the brainstem and cerebellum). In six patients with basilar invagination the medulla oblongata was herniated, all three occipital enchondral parts (the basiocciput, exocciput, and supraocciput) were significantly smaller than in the control group, and the volume ratio was significantly larger than that in the Chiari group without basilar invagination. These results suggest that in adult-type Chiari malformation an underdeveloped occipital bone, possibly due to underdevelopment of the occipital somite originating from the paraxial mesoderm, induces overcrowding in the posterior cranial fossa, which contains the normally developed hindbrain. Basilar invagination is associated with a more severe downward herniation of the hindbrain due to the more severely underdeveloped occipital enchondrium, which further exacerbates overcrowding of the posterior cranial fossa. SN - 0022-3085 UR - https://www.unboundmedicine.com/medline/citation/8988080/Pathogenesis_of_Chiari_malformation:_a_morphometric_study_of_the_posterior_cranial_fossa_ L2 - https://thejns.org/doi/10.3171/jns.1997.86.1.0040 DB - PRIME DP - Unbound Medicine ER -