Arnold-Chiari-II malformation and cognitive functioning in spina bifida

Abstract

Spina bifida is a multifaceted neurological condition with complex neuropsychological sequelae. The cognitive outcome in spina bifida has frequently been attributed to the severity of the hydrocephalus. However, because of complex neuropathology, the influence of hydrocephalus alone does not sufficiently explain the deficits in the cognitive profile in spina bifida. To date, little is known of the role of ArnoldChiari-II malformation (ACM) in the cognitive profile of these patients. Aim of the current study is to delineate the specific contribution of the ACM in spina bifida by comparing children with ACM and those without ACM. 46 children between 6 and 15 years of age underwent a neuropsychological assessment covering intelligence and a wide range of cognitive functions, such as visuo-motor processing, attention, memory, word fluency and speed of information processing. Comparisons were made between patients with ACM (ACM+) and those without ACM (ACM2); all children with ACM+ also had hydrocephalus. Confounding effects of global cognitive impairment were excluded, such that groups were matched on verbal IQ. Because of complex neuropathology, which is inherent to spina bifida, the method applied was based on a comparison of cognitive profiles of the study group with profiles of patients with cerebellar damage and hydrocephalus found in the literature. Impaired visual analysis and synthesis, verbal memory, and verbal fluency, even after correction for global cognitive impairment, were observed in children with ACM. The hypothesis that in addition to impairment in visual analysis and synthesis, which are related to both hydrocephalus and ACM, specific deficiencies in verbal memory and fluency may be attributed to ACM is supported. S pina bifida is a heterogeneous congenital disorder with complex physical and neuropsychological symptomatology. It is associated with developmental anomalies of both the spine and the central nervous system. Different forms of spina bifida can be distinguished, varying from mild to severe. The most common form is myelomeningocele. Nearly all children with myelomeningocoele develop a hydrocephalus and have Arnold-Chiari-II malformation (ACM). ACM includes a low tentorium insertion, herniation of the posterior fossa content and beaking of the mesencephalic tectum.

Desempenho funcional de crianças com mielomeningocele

“…O acometimento cognitivo é freqüentemente atribuído à hidrocefalia 25 . O percentual de hidrocefalia associada à MMC na literatura varia de 15 a 25% ao nascimento 26 até mais de 85% dos pacientes 3 .…”

An approach to the developmental and cognitive profile of the child with spina bifida

“…1). [1,4,5] Additional factors that have a role in determining the longterm neurocognitive outcome include epilepsy (and its treatment), endocrine complications and the impact of other medical complications, which may result in repeated hospitalisations.…”

Sleep disorder: a possible cause of attention deficit in children and adolescents with Chiari malformation type II

“…Myelomeningocele is present in almost all children with CM II and hydrocephalus is concomitantly seen in more than 70% of cases 1 . The increased prevalence of a variable degree of encephalic developmental anomalies observed in children with CM II may negatively affect their cognition 3 . Although presently, mostly due to improved diagnostic methods and precocious treatment, children with myelomeningocele and hydrocephalus are more likely to have an IQ within normal range 4 .…”

“…Consequently, in spite of the variable degree of CNS abnormalities, the majority of children with CM II are apt to Sleep disorder: Chiari malformation type II henriques Filho and Pratesi attend and follow a normal school program showing satisfactory performance and a socially acceptable degree of continence and behavior 4 . Besides the potential presence of cognitive difficulties, CM II patients are, mostly due to their brain stem anomalies, often affected by sleep disorders, the more frequently observed being sleep apneas, central hypoventilation and pulmonary restrictive disease 3,5 . Periodic limb movement in sleep (PlMS) may appear in association to spinal anomalies 6 , and would be another sleep disorder which could result in further cognitive impairment 7 .…”