Tuesday, February 10, 2009

A Wealth of Information From OEP

Welcome to the OEP Reference Center offers many Papers that shed light on numerous topics from retinoscopy and, critical periods to the The Scientific Basis for the Functional Approach to Vision Care .... DM

Sunday, February 8, 2009

A Clinician’s Guide to the Pathophysiology of Traumatic Brain Injury

Abstract: Traumatic brain injury induces a complex pathophysiological cascade of cellular events. Central components of this response include increases in cerebral glucose uptake, reductions in cerebral blood flow, indiscriminate excitatory neurotransmitter release, ionic disequilibrium, and intracellular calcium accumulation. Acute glutamate release and nonspecific neuronal depolarization induce threatening perturbations in neuronal function. Restoration of homeostasis requires significant increases in glucose metabolism; however, there is often a concomitant reduction in cerebral blood flow, resulting in an uncoupling of supply and demand. Understanding the nature and timing of these processes provides the practicing clinician with a mechanistic rationale for acute physiological monitoring, aggressive interventions to address and minimize secondary injuries, implementation of advanced neuroimaging techniques, and careful monitoring return to normal activity in head injured patients.

Computerized cognitive rehabilitative training of a traumatic brain injury patient: a seven year followup case study

Most research on computerized cognitive rehabilitation (CCR) for individuals with traumatic brain injury has focused on the process of the intervention and its immediate impact on memory and cognitive functioning (e.g., [1]). Few studies have examined the longterm impact of CCR on an individual's functioning. Even in a study where longer term outcomes were evaluated, the followup periods were six to twelve months and focused primarily on memory functioning [2]. This case study describes the longterm outcome of a middle aged male who had a traumatic brain injury as a result of hypoxia secondary to a heart attack. The patient had received CCR daily during the period of inpatient hospitalization. The CCR consisted of the PSSCogRehab program [3], which incorporates rehearsal, compensation, and strategies in various activities of daily living including in vivo trips to the grocery store and route finding [4]. After discharge from the inpatient unit, the patient self-administered the CCR protocol twice daily with supervised administration weekly and individual and couples psychotherapy twice a week. Over a period of two years, this was tapered to one psychotherapy session per week during which a few minutes were allotted to go over his progress on the CCR program and make adjustments, as necessary. A qualitative methodology utilizing written questionnaires and followup interviews was used to collect information in the areas of executive, interpersonal, and social functioning. This outcome study documents the return of functioning in cognitive abilities of an individual seven years post-injury. Executive, interpersonal, and social skills are also discussed.

Are mild head injuries as mild as we think? Neurobehavioral concomitants of chronic post-concussion syndrome

Background

Mild traumatic brain injury (MTBI) can sometimes lead to persistent postconcussion symptoms. One well accepted hypothesis claims that chronic PCS has a neural origin, and is related to neurobehavioral deficits. But the evidence is not conclusive. In the attempt to characterise chronic MTBI consequences, the present experiment used a group comparison design, which contrasted persons (a) with MTBI and PCS, (b) MTBI without PCS, and (c) matched controls. We predicted that participants who have experienced MTBI but show no signs of PCS would perform similar to controls. At the same time, a subgroup of MTBI participants would show PCS symptoms and only these volunteers would have poorer cognitive performance. Thereby, the performance deficits should be most noticeable in participants with highest PCS severity.

Method

38 patients with a single MTBI that had occurred at least 12 month prior to testing, and 38 matched controls, participated in the experiment. A combination of questionnaires and neuropsychological test batteries were used to assess the extent of PCS and related deficits in neurobehavioral performance.

Results

11 out of 38 MTBI participants (29%) were found to suffer from PCS. This subgroup of MTBI patients performed poorly on neuropsychological test batteries. Thereby, a correlation was found between PCS symptom severity and test performance suggesting that participants with more pronounced PCS symptoms performed worse in cognitive tasks. In contrast, MTBI patients with no PCS showed performed similar to matched control. We further found that loss of consciousness, a key criterion for PCS diagnosis, was not predictive of sustained PCS.

Conclusion

The results support the idea that MTBI can have sustained consequences, and that the subjectively experienced symptoms and difficulties in everyday situations are related to objectively measurable parameters in neurocognitive function.

The Axon Guidance Receptor Gene ROBO1 Is a Candidate Gene for Developmental Dyslexia

Dyslexia, or specific reading disability, is the most common learning disorder with a complex, partially genetic basis, but its biochemical mechanisms remain poorly understood. A locus on Chromosome 3, DYX5, has been linked to dyslexia in one large family and speech-sound disorder in a subset of small families. We found that the axon guidance receptor gene ROBO1, orthologous to the Drosophila roundabout gene, is disrupted by a chromosome translocation in a dyslexic individual. In a large pedigree with 21 dyslexic individuals genetically linked to a specific haplotype of ROBO1 (not found in any other chromosomes in our samples), the expression of ROBO1 from this haplotype was absent or attenuated in affected individuals. Sequencing of ROBO1 in apes revealed multiple coding differences, and the selection pressure was significantly different between the human, chimpanzee, and gorilla branch as compared to orangutan. We also identified novel exons and splice variants of ROBO1 that may explain the apparent phenotypic differences between human and mouse in heterozygous loss of ROBO1. We conclude that dyslexia may be caused by partial haplo-insufficiency for ROBO1 in rare families. Thus, our data suggest that a slight disturbance in neuronal axon crossing across the midline between brain hemispheres, dendrite guidance, or another function of ROBO1 may manifest as a specific reading disability in humans.

Can the Bruckner test be used as a rapid screening test to detect significant refractive errors in children?

Purpose: To assess the suitability of Brückner test as a screening test to detect significant refractive errors in children. Materials and Methods: A pediatric ophthalmologist prospectively observed the size and location of pupillary crescent on Brückner test as hyperopic, myopic or astigmatic. This was compared with the cycloplegic refraction. Detailed ophthalmic examination was done for all. Sensitivity, specificity, positive predictive value and negative predictive value of Brückner test were determined for the defined cutoff levels of ametropia. Results: Ninety-six subjects were examined. Mean age was 8.6 years (range 1 to 16 years). Brückner test could be completed for all; the time taken to complete this test was 10 seconds per subject. The ophthalmologist identified 131 eyes as ametropic, 61 as emmetropic. The Brückner test had sensitivity 91%, specificity 72.8%, positive predictive value 85.5% and negative predictive value 83.6%. Of 10 false negatives four had compound hypermetropic astigmatism and three had myopia. Conclusions: Brückner test can be used to rapidly screen the children for significant refractive errors. The potential benefits from such use may be maximized if programs use the test with lower crescent measurement cutoffs, a crescent measurement ruler and a distance fixation target.

A community-based study of asthenopia in computer operators

There is growing body of evidence that use of computers can adversely affect the visual health. Considering the rising number of computer users in India, computer-related asthenopia might take an epidemic form. In view of that, this study was undertaken to find out the magnitude of asthenopia in computer operators and its relationship with various personal and workplace factors.
Aims: To study the prevalence of asthenopia among computer operators and its association with various epidemiological factors.
Settings and Design: Community-based cross-sectional study of 419 subjects who work on computer for varying period of time.
Materials and Methods: Four hundred forty computer operators working in different institutes were selected randomly. Twenty-one did not participate in the study, making the nonresponse rate 4.8%. Rest of the subjects (n = 419) were asked to fill a pre-tested questionnaire, after obtaining their verbal consent. Other relevant information was obtained by personal interview and inspection of workstation.
Statistical Analysis Used: Simple proportions and Chi-square test.
Results: Among the 419 subjects studied, 194 (46.3%) suffered from asthenopia during or after work on computer. Marginally higher proportion of asthenopia was noted in females compared to males. Occurrence of asthenopia was significantly associated with age of starting use of computer, presence of refractive error, viewing distance, level of top of the computer screen with respect to eyes, use of antiglare screen and adjustment of contrast and brightness of monitor screen.
Conclusions: Prevalence of asthenopia was noted to be quite high among computer operators, particularly in those who started its use at an early age. Individual as well as work-related factors were found to be predictive of asthenopia.

Neurobiology of Memory and Anxiety: From Genes to Behavior

Interaction of anxiety and memory represents an essential feature of CNS functioning. This paper reviews experimental data coming from neurogenetics, neurochemistry, and behavioral pharmacology (as well as parallel clinical findings) reflecting different mechanisms of memory-anxiety interplay, including brain neurochemistry, circuitry, pharmacology, neuroplasticity, genes, and gene-environment interactions. It emphasizes the complexity and nonlinearity of such interplay, illustrated by a survey of anxiety and learning/memory phenotypes in various genetically modified mouse models that exhibit either synergistic or reciprocal effects of the mutation on anxiety levels and memory performance. The paper also assesses the putative role of different neurotransmitter systems and neuropeptides in the regulation of memory processes and anxiety, and discusses the role of neural plasticity in these mechanisms.

Visual status of industrial workers

...Two hundred and eighty four industrial workers were screened to determine their visual acuity. Significant visual impairment was observed in 21.8% individuals and moderate impairment in 34.5% of cases. Convergence insufficiency was a problem in 9.86% of the workers. Since uncorrected refractive errors are a prelude to disastrous workplace related eye injuries, it is recommended that prior to job placement all workers undergo visual acuity screening and get their refractive errors rectified.

Role of orthoptic treatment in the management of intermittent exotropia

...30 patients of intermittent ACDS were studied prospectively for a period of 8 weeks to 1 year to evaluate the role of orthoptics in the management of these cases. In patients with convergence insufficiency and a maximum deviation of 25 PD or less the orthoptic treatment was found to be effective in offering symptomatic relief and improving binocular functional status. A reduction in the maximum angle of deviation by 4 PD to 8 PD was observed in 4 patients. Even though the basic angle of deviation remained unchanged in most of the patients, significant functional and symptomatic improvement was obtained in 64% to 85.7% of these cases. The long term stability of these results remains to be studied. In patients with a deviation of more than 25 PD there was no significant improvement in symptoms or reduction in maximum angle of deviation. In 6(37.5%) of these patients some improvement in the fusional range could be demonstrated on the synoptophore without any symptomatic relief.

Tourette syndrome and learning disabilities

Background

Tourette Syndrome (TS) is a neurodevelopmental disorder of childhood. Learning disabilities are frequently comorbid with TS. Using the largest sample of TS patients ever reported, we sought to identify differences between subjects with TS only and subjects with TS and a comorbid learning disability.

Methods

We used the Tourette Syndrome International Consortium database (TIC) to compare subjects with comorbid Tourette Syndrome and learning disabilities (TS + LD) to subjects who did not have a comorbid learning disability (TS - LD). The TIC database contained 5,500 subjects. We had usable data on 5,450 subjects.

Results

We found 1,235 subjects with TS + LD. Significant differences between the TS + LD group and the TS - LD group were found for gender (.001), age onset (.030), age first seen (.001), age at diagnosis (.001), prenatal problems (.001), sibling or other family member with tics (.024), two or more affected family members (.009), and severe tics (.046). We used logistic modeling to identify the optimal prediction model of group membership. This resulted in a five variable model with the epidemiologic performance characteristics of accuracy 65.2% (model correctly classified 4,406 of 5,450 subjects), sensitivity 66.1%, and specificity 62.2%.

Conclusion

Subjects with TS have high prevalence rates of comorbid learning disabilities. We identified phenotype differences between the TS - LD group compared to TS + LD group. In the evaluation of subjects with TS, the presence of a learning disability should always be a consideration. ADHD may be an important comorbid condition in the diagnosis of LD or may also be a potential confounder. Further research on etiology, course and response to intervention for subjects with TS only and TS with learning disabilities is needed.

Comparison of cognition abilities between groups of children with specific learning disability having average, bright normal and superior nonverbal in

...BACKGROUND: Specific learning disabilities (SpLD) viz. dyslexia, dysgraphia and dyscalculia are an important cause of academic underachievement. Aims: To assess whether cognition abilities vary in children with SpLD having different grades of nonverbal intelligence. SETTING: Government recognized clinic in a medical college. DESIGN: Cross-sectional study. SUBJECTS AND METHODS: Ninety-five children with SpLD (aged 9-14 years) were assessed. An academic achievement of two years below the actual grade placement on educational assessment with a Curriculum-Based test was considered diagnostic of SpLD. On basis of their nonverbal Intelligence Quotient (IQ) scores obtained on the Wechsler Intelligence Scale for Children test, the study children were divided into three groups: (i) average-nonverbal intelligence group (IQ 90-109), (ii) bright normal-nonverbal intelligence group (IQ 110-119), and (iii) superior-nonverbal intelligence group (IQ 120-129). A battery of 13 Cognition Function tests (CFTs) devised by Jnana Prabodhini's Institute of Psychology, Pune based on Guilford's Structure of Intellect Model was administered individually on each child in the four areas of information viz. figural, symbolic, semantic and behavioral. STATISTICAL ANALYSIS USED: The mean CFTs scores obtained in the four areas of information were calculated for each of the three groups and compared using one-way analysis of variance test. A P value <>

Psychological Co morbidity in Children and Adolescents with Learning Disorders

...Learning disabilities are frequently associated with psychological problems (Rutter, 1974;
Willcutt & Pennington, 2000). Results of population based surveys suggest that about
30% of learning disabled children have behavioural and emotional problems (Mc Gee et
al, 1984). Psychopathology worsens with age in children with non-verbal learning
disabilities (Rourke, 1988). Marked anxiety can appear when children with dyscalculia
are confronted with reasonably simple arithmetic problems (Garnett & Fleischner, 1987).
Ekblad (1990) found a positive correlation between psychological disturbance and poor
school achievement among Chinese children. Shenoy & Kapur (1996) noted that 21 out
of 88 children with learning disability had a co-morbid psychological diagnosis. Kishore
et al (2000) reported that 21 out of 56 children with specific developmental disorders of
scholastic skills had a co-morbid psychological
disorder....

Comments: The full text article is available by clicking on the title above. DM

PREVALENCE OF MINOR CONGENITAL ANOMALIES IN CHILDREN WITH HYPERACTIVITY

Abstract. A congenital anomaly is a physical, metabolic, or anatomic deviation from the normal pattern of development that is present at birth. Minor congenital anomalies do not have medical or cosmetic importance, but detection of more than three such anomalies may reveal the prenatal origin of a disorder. The aim of the present study was to establish an association between the presence of minor congenital anomalies and hyperactivity, learning disabilities and attention deficit. 219 patients aged between 7 and 18 years were examined for the presence of minor congenital anomalies and compared to a control group. The frequencies of these anomalies were not significantly different in the two groups. The mean values of minor congenital anomalies per child were significantly different: 2.5 in children with learning disabilities, 4 in those with learning disabilities and attention deficit and hyperactivity, 1.05 in the control group. Prevention is the best approach to congenital anomalies. As a positive correlation could be established, it was concluded that the presence of minor congenital anomalies especially more than three, may predict the future onset of these disorders.

Comments: This full text article is free if you click on the title above. DM

Survivors of retinoblastoma may face increased risk of second cancers, research suggests.

From AOA FirstLook:



Cancer Consultants (2/6, Weaver) reports that, according to a study published in the Journal of the National Cancer Institute, there appears to be "a high risk of second cancers among survivors of hereditary retinoblastoma," a "rare cancer of the retina" that "most commonly occurs in young children." In arriving at that conclusion, "researchers in the Netherlands conducted a study among 668 patients who had been diagnosed with retinoblastoma between 1945 and 2005. The risk of cancer in the retinoblastoma survivors was compared to the risk of cancer in the general Dutch population." The authors found that, "among survivors of hereditary retinoblastoma, the risk of cancer was 20-times higher than in the general population," with "patients who had received radiation therapy for hereditary retinoblastoma" having "an even greater increase in subsequent cancer risk."

What Your Mother Did When She Was A Child May Have An Effect On Your Memory

...A study reveals that the severity of learning disorders may depend not only on the child's environment but also – remarkably – on the mother's environment when she was young...

Vernier Acuity in Down Syndrome

....Vernier thresholds were successfully measured in children with DS and were found to be reduced, indicating that cortical visual function is compromised. Impairment in cortical function in DS may be implicit, relating to histologic reports of differences in the DS brain, or they may result from abnormal experience during visual development. The magnitude of the cortical deficit demonstrated in DS in the present study is significant and should be considered along with previously reported poor optical quality....

Recommended Adult Immunization Schedule --- United States, 2009

Comments: I didn't even know that there was a recommended schedule for adults! DM

The Advisory Committee on Immunization Practices (ACIP) annually reviews the recommended Adult Immunization Schedule to ensure that the schedule reflects current recommendations for the licensed vaccines. In October 2008, ACIP approved the Adult Immunization Schedule for 2009. No new vaccines were added to the schedule; however, several indications were added to the pneumococcal polysaccharide vaccine footnote, clarifications were made to the footnotes for human papillomavirus, varicella, and meningococcal vaccines, and schedule information was added to the hepatitis A and hepatitis B vaccine footnotes.

The Role of Face Familiarity in Eye Tracking of Faces by Individuals with Autism Spectrum Disorders

...Eye movements of 18 typically developing participants and 17 individuals with ASD were recorded while passively viewing three face categories: unfamiliar non-repeating faces, a repeating highly familiar face, and a repeating previously unfamiliar face. Results suggest that individuals with ASD do not exhibit more normative gaze patterns when viewing familiar faces. A second task assessed facial recognition accuracy and response time for familiar and novel faces. The groups did not differ on accuracy or reaction times.

Brief Report: Young Adults with Autism Spectrum Disorder Show Normal Attention to Eye-Gaze Information—Evidence from a New Change Blindness Paradigm

...We investigated whether young adults would detect a change to the direction of eye-gaze in another’s face more efficiently than a control change (presence/absence of spectacles). A change blindness method was used in which images showed faces as part of a complex, naturalistic scene. Results showed that adults with ASD, like typically developing controls, were faster and more accurate at detecting eye-gaze than control changes....

A review on eye movement studies in childhood and adolescent psychiatry

........... Visually guided saccades, antisaccades, memory guided saccades, and smooth pursuit eye movements will be reviewed in various childhood psychiatric disorders. The four aims of this review are (1) to give a thorough overview of eye movement studies in a wide array of psychiatric disorders occurring during childhood and adolescence (attention-deficit/hyperactivity disorder, oppositional deviant disorder and conduct disorder, autism spectrum disorders, reading disorder, childhood-onset schizophrenia, Tourette’s syndrome, obsessive compulsive disorder, and anxiety and depression), (2) to discuss the specificity and overlap of eye movement findings across disorders and paradigms, (3) to discuss the developmental aspects of eye movement abnormalities in childhood and adolescence psychiatric disorders, and (4) to present suggestions for future research. In order to make this review of interest to a broad audience, attention will be given to the clinical manifestation of the disorders and the theoretical background of the eye movement paradigms...............

Blue or Red? Exploring the Effect of Color on Cognitive Task Performances

...Existing research reports inconsistent findings with regard to the effect of color on cognitive task performances. Some research suggests that blue or green leads to better performances than red; other studies record the opposite. Current work reconciles this discrepancy. We demonstrate that red (versus blue) color induces primarily an avoidance (versus approach) motivation (study 1, n = 69) and that red enhances performance on a detail-oriented task, whereas blue enhances performance on a creative task (studies 2 and 3, n = 208 and 118). Further, we replicate these results in domains of product design (study 4, n = 42) and persuasive message evaluation (study 5, n = 161), and illustrate that these effects occur outside of individuals’ consciousness (study 6, n = 68). We also provide process evidence suggesting that the activation of alternative motivations mediates the effect of color on cognitive task performances....