Cerebellar motor function in spina bifida meningomyelocele.

Dennis M, Salman MS, Juranek J, Fletcher JM (2010) Cerebellar motor function in spina bifida meningomyelocele. Cerebellum. 2010 Dec;9(4):484-98.

Spina bifida meningomyelocele (SBM), a congenital neurodevelopmental disorder, involves dysmorphology of the cerebellum, and its most obvious manifestations are motor deficits. This paper reviews cerebellar neuropathology and motor function across several motor systems well studied in SBM in relation to current models of cerebellar motor and timing function. Children and adults with SBM have widespread motor deficits in trunk, upper limbs, eyes, and speech articulators that are broadly congruent with those observed in adults with cerebellar lesions. The structure and function of the cerebellum are correlated with a range of motor functions. While motor learning is generally preserved in SBM, those motor functions requiring predictive signals and precise calibration of the temporal features of movement are impaired, resulting in deficits in smooth movement coordination as well as in the classical cerebellar triad of dysmetria, ataxia, and dysarthria. That motor function in individuals with SBM is disordered in a manner phenotypically similar to that in adult cerebellar lesions, and appears to involve similar deficits in predictive cerebellar motor control, suggests that age-based cerebellar motor plasticity is limited in individuals with this neurodevelopmental disorder.

PMID: 20652468

 

The cerebellum in children with spina bifida and Chiari II malformation: Quantitative volumetrics by region.

Juranek J, Dennis M, Cirino PT, El-Messidi L, Fletcher JM. (2010) The cerebellum in children with spina bifida and Chiari II malformation: Quantitative volumetrics by region. Cerebellum. 2010 Jun;9(2):240-8.

Few volumetric MRI studies of the entire cerebellum have been published; even less quantitative information is available in patients with hindbrain malformations, including the Chiari II malformation which is ubiquitous in patients with spina bifida meningomyelocele (SBM). In the present study, regional volumetric analyses of the cerebellum were conducted in children with SBM/Chiari II and typically developing (TD) children. Total cerebellar volume was significantly reduced in the SBM group relative to the TD group. After correcting for total cerebellum volume, and relative to the TD group, the posterior lobe was significantly reduced in SBM, the corpus medullare was not different, and the anterior lobe was significantly enlarged. Children with thoracic level lesions had smaller cerebellar volumes relative to those with lumbar/sacral lesions, who had smaller volumes compared to TD children. The reduction in cerebellar volume in the group with SBM represents not a change in linear scaling but rather a reconfiguration involving anterior lobe enlargement and posterior lobe reduction.

PMID: 20143197

Anomalous development of brain structure and function in spina bifida myelomeningocele.

Juranek J, Salman MS. (2012) Anomalous development of brain structure and function in spina bifida myelomeningocele.
Dev Disabil Res Rev. 2010;16(1):23-30.

Spina bifida myelomeningocele (SBM) is a specific type of neural tube defect whereby the open neural tube at the level of the spinal cord alters brain development during early stages of gestation. Some structural anomalies are virtually unique to individuals with SBM, including a complex pattern of cerebellar dysplasia known as the Chiari II malformation. Other structural anomalies are not necessarily unique to SBM, including altered development of the corpus callosum and posterior fossa. Within SBM, tremendous heterogeneity is reflected in the degree to which brain structures are atypical in qualitative appearance and quantitative measures of morphometry. Hallmark structural features of SBM include overall reductions in posterior fossa and cerebellum size and volume. Studies of the corpus callosum have shown complex patterns of agenesis or hypoplasia along its rostral-caudal axis, with rostrum and splenium regions particularly susceptible to agenesis. Studies of cortical regions have demonstrated complex patterns of thickening, thinning, and gyrification. Diffusion tensor imaging studies have reported compromised integrity of some specific white matter pathways. Given equally complex ocular motor, motor, and cognitive phenotypes consisting of relative strengths and weaknesses that seem to align with altered structural development, studies of SBM provide new insights to our current understanding of brain structure-function associations.

PMID: 20419768

Selective and sustained attention in children with spina bifida myelomeningocele

Caspersen ID, Habekost T. (2012) Selective and sustained attention in children with spina bifida myelomeningocele. Child Neuropsychology. 2012 Jan 11.

Spina bifida myelomeningocele (SBM) is a neural tube defect that has been related to deficits in several cognitive domains including attention. Attention function in children with SBM has often been studied using tasks that are confounded by complex motor demands or tasks that do not clearly distinguish perceptual from response-related components of attention. We used a verbal-report paradigm based on the Theory of Visual Attention ( Bundesen, 1990 ) and a new continuous performance test, the Dual Attention to Response Task ( Dockree et al., 2006 ), for measuring parameters of selective and sustained attention in 6 children with SBM and 18 healthy control children. The two tasks had minimal motor demands, were functionally specific and were sensitive to minor deficits. As a group, the children with SBM were significantly less efficient at filtering out irrelevant stimuli. Moreover, they exhibited frequent failures of sustained attention and response control in terms of omission errors, premature responses, and prolonged inhibition responses. All 6 children with SBM showed deficits in one or more parameters of attention; for example, three patients had elevated visual perception thresholds, but large individual variation was evident in their performance patterns, which highlights the relevance of an effective case-based assessment method in this patient group. Overall, the study demonstrates the strengths of a new testing approach for evaluating attention function in children with SBM.


PMID: 22235979

Nonverbal learning disabilities: a critical review.

Spreen O. (2011) Nonverbal learning disabilities: a critical review. Child Neuropsychol. 2011 Sep;17(5):418-43.

This article presents a critical review of the term and concept of nonverbal learning disability (NLD). After a brief historical introduction, the article focuses on the apparent rarity of NLD; the hypothesis of the frequent co-occurrence of emotional disorder, depression, and suicide in NLD; the white matter hypothesis as an explanation of the origin of NLD; and the question of NLD as part of a variety of other disorders. It is argued that NLD presents a broad hypothesis, but that there is little evidence to support its use in clinical practice.



PMID: 21462003

Goal-directed behavior and perception of self-competence in children with spina bifida.

Landry SH, Robinson SS, Copeland D, Garner PW. (1993) Goal-directed behavior and perception of self-competence in children with spina bifida. J Pediatr Psychol. 1993 Jun;18(3):389-96.

Compared a group of school-age children with spina bifida (n = 15) between the ages of 6 and 12 years with an age- and IQ-matched control group of normal children (n = 15). As predicted, the spina bifida children spent less time using goal-directed behaviors and more time in simple manipulation of the toys compared to the normal children. There were no group differences between the spina bifida and normal children's perceived competence but parents of the spina bifida children rated their children as having lower cognitive and physical competence. Associations were found between goal-directed behaviors and perceived self-competence for children in the spina bifida group but not the normal group.

PMID: 8340846

Goal-directed behavior in children with spina bifida.

Landry SH, Copeland D, Lee A, Robinson S. (1990) Goal-directed behavior in children with spina bifida. J Dev Behav Pediatr. 1990 Dec;11(6):306-11.

A group of school-age children with spina bifida (n = 15) between the ages of 6 and 12 years were compared with an age- and IQ-matched control group of normal children (n = 15). Goal-directed behavior in these two groups was measured by videotaped observational measures of the number of different task-oriented play activities the children performed and the amount of time they spent in independent task-oriented activities. Measures of time spent off-task and in simple manipulation of the play materials were taken, as well as the number of social initiations the child directed to the examiner. The children with spina bifida spent less time in task-oriented activities than the control group, even though there were no group differences in the number of activities performed. The differences could not be explained by cognitive impairments or socioeconomic factors. These results suggest that children with spina bifida may have specific problems with sustaining goal-directed behavior, and need assistance in formulating and implementing a sequence of actions in order to achieve concrete short-term goals.

PMID: 2149725