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ABSTRACT
Chiari I malformation, a congenital abnormality in which deformed cerebellar tonsils are displaced downward through the foramen magnum, commonly presents in patients with headache or symptoms of dysfunction of the cerebellum, brain stem, and cervical spinal cord. We report 11 children with Chiari I malformation who presented with seizures and developmental delay in motor or language function with or without autistic features. To our knowledge, an association between Chiari I malformation and seizures or neurodevelopmental deficits or both has not been previously reported. We believe that Chiari I malformation should not be considered an incidental finding in these patients, but may be a marker for subtle cerebral dysgenesis. Chiari I and II malformations may constitute a complex but continuous spectrum, related to the timing and severity of a shared underlying embryologic mechanism. (J Child Neurol 1997;12:101-106).
Chiari I malformation, a congenital abnormality in which there is displacement of deformed cerebellar tonsils below the foramen magnum, with normal intracranial pressure and no other posterior fossa or supratentorial abnormality, has been reported in children and adults with cerebellar, brainstem and upper cervical spine symptoms, scoliosis, headache, and occasionally in patients with open and closed neural tube defects.1-6
Midline developmental brain defects, including cavum vergae,7 wide cavum septui pellucidui,8 hypoplastic corpus callosum,9 colpocephaly,10 and macro-cisterna magna11 have been found in patients with developmental disabilities including seizures and motor and speech delay. We evaluated 11 children who presented with these symptoms and who were found to have a Chiari I malformation. Cerebellar influences on learning, language, behavior, emotional, and cognitive functions have been found.12,13 We suggest that Chiari I malformation be considered another marker of disturbed midline brain development that may be associated with seizures and cognitive symptoms.
An embryologic mechanism exists that may tie Chiari I and II malformations together, and explain how they may be associated with subtle cerebral dysgenesis and resultant cognitive symptoms. In open neural tube defects, loss of cerebrospinal fluid through a fistulous central canal14 led to low embryonic cerebrospinal fluid pressure, which may lead to the formation of Chiari II malformation,15 including its associated cerebral dysplasias.16 We hypothesize that a similar mechanism, differing in timing and severity, gives rise to the Chiari I malformation and offers an explanation for the...