Cognition in Pediatric Chiari Malformation Type 1 Before and After Posterior Fossa Decompression

Chiari malformation type 1 (CM1) is a condition that affects the hindbrain. The diagnosis is based on the radiologic finding of a descent of the cerebellar tonsils 5 mm or more below the level of the foramen magnum. Although often asymptomatic, CM1 can cause occipital headache or neurologic symptoms. Cognitive symptoms in patients with CM1 have not been explored extensively. This study aimed to fill the knowledge gap regarding cognitive symptoms in children with CM1 and the effects of neurosurgery on these symptoms.

Eleven consecutive pediatric surgical patients with CM1, without known comorbidities (mean age, 11 years), were evaluated cognitively before and after posterior fossa decompression. The assessments included the Wechsler Scales of Intelligence in Children, fifth edition (WISC-V), Boston Naming Test (BNT), Rey Auditory Verbal Learning Test (RAVLT), verbal fluency test (FAS), and Rey Complex Figure Test (RCFT). Results from preoperative and postoperative tests were compared.

All presurgical results, except for picture naming, were within the average range. However, significant postsurgical improvements were observed in overall cognitive ability, visuospatial skills, nonverbal logical reasoning, and processing speed. Significant improvements also were found in executive functions and visuospatial memory.

The children in this study scored within the average range on cognitive tests before surgery compared to age-adjusted norms. After surgery, the test results improved significantly in several domains or remained stable at the preoperative level. These findings are important and could influence surgical decisions for children with CM1.