• Journal of Korean Neurosurgical Society
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• v.59 no.5
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• pp.512-517
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• 2016

Objective : The pathophysiology of idiopathic Chiari malformation (CM) type 1 is disturbance of free cerebrospinal fluid (CSF) flow and restoration of normal CSF flow is the mainstay of treatment. Additional migration of the medulla oblongata in pediatric patients is referred to as CM type 1.5, but its significance in adult patients is unknown. This study is to compare surgical outcomes of adult idiopathic CM type 1.5 with that of type 1. Methods : Thirty-eight consecutive adult patients (M : F=11 : 27; median, 33.5; range, 18-63) with syringomyelia due to idiopathic CM type 1 were reviewed. Migration of the medulla oblongata was noted in 13 patients. The modified McCormick scale (MMS) was used to evaluate functional status before and one year after surgery. All patients underwent foramen magnum decompression and duroplasty. Factors related to radiological success (${\geq}50%$ decrease in the diameter of the syrinx) were investigated. The follow-up period was $72.7{\pm}55.6$ months. Results : Preoperative functional status were MMS I in 11 patients and MMS II in 14 of CM type 1 and MMS I in 8 and II in 5 of CM type 1.5. Of patients with MMS II, 5/14 patients in group A and 3/5 patients in group B showed improvement and there was no case of deterioration. Radiological success was achieved in 32 (84%) patients and restoration of the cisterna magna (p=0.01; OR, 46.5) was the only significant factor. Conclusion : Migration of the medulla oblongata did not make a difference in the surgical outcome when the cisterna magna was restored.

• Journal of Korean Neurosurgical Society
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• v.66 no.4
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• pp.393-399
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• 2023

Objective : Chiari II malformation (CM II) is still the main cause of severe morbidity and mortality in children with open neural tube defects (ONTDs). The goal of this study was to validate a CM II model in late-stage chick embryos with surgically induced ONTDs. Methods : To make the chick embryo model of ONTD, their neural tubes were opened for a length of 5-6 somites at the thoracic level in Hamburger and Hamilton stage 18 chick embryos (n=150). They were reincubated in ovo up to a total age of 17-21 days. A total of 19 embryos survived and were assigned to either the postoperative day (POD) 14-15 group (n=6) or the POD 17-18 group (n=13). Magnetic resonance imaging (MRI) and histopathologic findings of embryo heads with spinal ONTDs were compared with age-matched normal chick embryos. Results : The chick embryos with ONTDs demonstrated definite and constant structural changes, such as downward displacement of the cerebellum to just above the foramen magnum and narrow and small cerebrospinal fluid spaces in the crowded small posterior fossa. These morphologic features were more prominent in the POD 17-18 group than in the POD 14-15 group. Conclusion : This is the first description of CM II with spinal ONTD in a late-stage chick embryo model with MRI and histopathological analysis. The morphological changes of the posterior fossa in this study mimic those of CM II associated with spinal ONTD in humans. This model will facilitate investigation of the pathogenesis of CM II.