Herniación amigdalina en la malformación de Chiari I en la edad pediátrica: observación y evolución en el tiempo

Abstract

ObjetiveTo assess possible changes in Chiari type I malformation in pediatric patients. Material and methods. A retrospective study of patients dianosed as having Chiari type I malformation, without surgical intervention, who had undergone at least one follow-up imaging study after an interval of at least one year. The diagnosis was established by sagittal magnetic resonance images showing displacement of the cerebellar tonsils of more than 5 mm through the foramen magnum. The clinical data, degree of tonsillar herniation and associated intracranial and medullary anomalies were recorded. The relationships between the degree of tonsillar herniation and the presence of associated symptoms and of medullary cavity, respectively, were analyzed using the chisquare test with Fisher's exact test and the positive likelihood ratio. ResultsEleven patients (7 boys and 4 girls) ranging in age between 4 months and 14 years (men: 6.5 years) were studied. At diagnosis, the egree of tonsillar herniation ranged between 6 mm and 20 mm. The finding was considered incidental in 9 of the 11 cases (81%); the remaining two patients presented headache and neck pain. The follow-up imaging studies were performed after an interval of 13 to 79 months. Stability of the herniation was observed in 6 patients (54%), progression in 3 (27%), a reduction in 1 (9%) and spontaneous regression in 1 (9%). Two patients presented neurofibromatosis type I accompanied by the characteristic intracranial lesions. Focal subcortical heterotopia was observed in another. Medullary cavities were found in 2 asymptomatic patients (18%). There was no significant relationship between the degree of herniation and the presence of either symptoms or medullary cavities. DiscussionIn children, Chiari type I malformation is often discovered incidentally. Associated medullary cavity is less common than in adults, suggesting that this phenomenon develops over the long term. During the course of the disease, nearly half the patients presented changes in tonsillar herniation, including an exceptional case of spontaneous regression of the malformation.