Chiari malformation

• The Arnold Chiari Malformation is an elongated cerebellar vermis that herniates through the foramen magnum, compressing the brain stem.
• Type I: only the cerebellar tonsils extend into the foramen magnum (most common, may be asymptomatic adult)
• Type II: cerebellar tonsils and brainstem tissue extend into foramen magnum. Associated with myelomeningocele.
• Type III: Herniation of cerebellum, brain stem and possibly the fourth ventricle through the foramen magnum.
• Type IV: cerebellar hypoplasia

-Type III and IV are less common but much more serious. -Common pediatric presentations including swallowing difficulty, recurrent aspiration, stridor, apneic episodes, and lack of gag reflex -Often associated with syringomyelia and therefore arm weakness and sensory deficits