Brain malformations and cognitive performance in spina bifida

To systematically characterize radiological features of patients with spina bifida, their relationship to cognitive function, and differences between spina bifida aperta (SBA) and spina bifida occulta (SBO).

In a retrospective study of 265 patients (117 females, 148 males; median age at imaging 11y, range 1-47y; SBA n=206, SBO n=59), the radiological phenotype was assessed through magnetic resonance imaging (MRI) (SBA n=171, SBO n=59). In 126 patients (SBA n=116, SBO n=10) Kaufman Assessment Battery for Children (KABC) or Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) and Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV) were performed.

Patients with spina bifida show numerous brain malformations, always present for SBA but rarely for SBO. The most frequent brain malformations in SBA included abnormal corpus callosum (69%), hypoplastic pons (50%), and hypoplastic mesencephalon (20%). Cognitive total IQ scores were below average in 44% (KABC) to 49% (WISC-IV) of children with SBA, while almost all children with SBO scored at least average. Stenogyria (p=0.006), pons (p=0.003), and mesencephalon hypoplasia (p=0.01) correlated with lower total IQ score and verbal comprehension. Various brain malformations correlate significantly with several cognitive domains, while lesion level only correlates with processing speed.

IQ scores were significantly lower in patients with SBA than in patients with SBO. Verbal competence, perceptual reasoning, and working memory were significantly impaired for SBA and correlated with stenogyria and abnormalities of the midbrain and corpus callosum.

Brain malformations occur more frequently in spina bifida aperta (SBA) than in spina bifida occulta (SBO). Cognitive impairment is less frequent in SBO. Hydrocephalus, stenogyria, midbrain, and corpus callosum abnormalities are associated with lower cognitive function. Difference in prognosis in SBO versus SBA can alter prenatal counselling.