Bilateral population receptive fields in congenital hemihydranencephaly

Purpose: Congenital hemihydranencephaly (HH) is a very rare disorder characterised by prenatal near-complete unilateral loss of the cerebral cortex. We investigated a patient affected by congenital right HH whose visual field extended significantly into the both visual hemifields, suggesting a reorganisation of the remaining left visual hemisphere. We examined the early visual cortex reorganisation using functional MRI (7T) and population receptive field (pRF) modelling. Methods: Data were acquired by means of a 7T MRI while the patient affected by HH viewed conventional population receptive field mapping stimuli. Two possible pRF reorganisation schemes were evaluated: where every cortical location processed information from either (i) a single region of the visual field or (ii) from two bilateral regions of the visual field. Results: In the patient affected by HH, bilateral pRFs in single cortical locations of the remaining hemisphere were found. In addition, using this specific pRF reorganisation scheme, the biologically known relationship between pRF size and eccentricity was found. Conclusions: Bilateral pRFs were found in the remaining left hemisphere of the patient affected by HH, indicating reorganisation of intra-cortical wiring of the early visual cortex and confirming brain plasticity and reorganisation after an early cerebral damage in humans

Bilateral population receptive fields in congenital hemihydranencephaly

PURPOSE: Congenital hemihydranencephaly (HH) is a very rare disorder characterised by prenatal near-complete unilateral loss of the cerebral cortex. We investigated a patient affected by congenital right HH whose visual field extended significantly into the both visual hemifields, suggesting a reorganisation of the remaining left visual hemisphere. We examined the early visual cortex reorganisation using functional MRI (7T) and population receptive field (pRF) modelling. METHODS: Data were acquired by means of a 7T MRI while the patient affected by HH viewed conventional population receptive field mapping stimuli. Two possible pRF reorganisation schemes were evaluated: where every cortical location processed information from either (i) a single region of the visual field or (ii) from two bilateral regions of the visual field. RESULTS: In the patient affected by HH, bilateral pRFs in single cortical locations of the remaining hemisphere were found. In addition, using this specific pRF reorganisation scheme, the biologically known relationship between pRF size and eccentricity was found. CONCLUSIONS: Bilateral pRFs were found in the remaining left hemisphere of the patient affected by HH, indicating reorganisation of intra-cortical wiring of the early visual cortex and confirming brain plasticity and reorganisation after an early cerebral damage in humans

Perimetry in young and neurologically impaired children : The Behavioral Visual Field (BEFIE) Screening Test revisited

IMPORTANCE: Visual field examination in young or neurologically impaired children is a challenge. As a result, the Behavioral Visual Field (BEFIE) Screening Test was developed in 1995. OBJECTIVES: To evaluate the applicability of the BEFIE test in a large population of young or neurologically impaired children, its reliability and consistency of findings across time, and its potential diagnostic value compared with standard conventional perimetry. DESIGN, SETTING, AND PARTICIPANTS: The BEFIE tests were performed at an academic tertiary center and measured the peripheral visual field extension in degrees by observing an individual's response to a stimulus on a graded arc that moved from the periphery to the center of the visual field along different meridians. Patient files from all children who underwent this test were retrospectively analyzed. In total, 1788 BEFIE tests were performed in 835 children (median age, 3.4 years). MAIN OUTCOMES AND MEASURES: Reliability and results of all tests were longitudinally evaluated. The diagnostic value of the BEFIE test was assessed by comparing monocular BEFIE test results with those of standard conventional perimetry in children who underwent both. RESULTS: Of 1788 tests, 74% (95% CI, 72%-76%) were considered reliable from the age of 4 months and older, with increasing success with higher ages; 56% reliable in children younger than 1 year; 71% reliable in children between 1 and 2 years; and more than 75% reliable in children 2 years and older (Spearman r = 0.506; P = .11). Peripheral visual field defects were found in 28% (95% CI, 25%-31%) of all first reliable tests. In 75% of children who underwent serial testing, results were consistent and there were good explanations in the case of discrepancies. Comparison of monocular BEFIE tests with standard conventional perimetry results in 147 eyes yielded a positive predictive value of 98% (95% CI, 94%-100%), negative predictive value of 66% (95% CI, 56%-75%), specificity of 98% (95% CI, 95%-100%), sensitivity of 60% (95% CI, 50%-71%), and superior sensitivity of 80% (95% CI, 70%-91%) when only absolute peripheral visual field defects at standard conventional perimetry were accounted for. CONCLUSIONS AND RELEVANCE: These data suggest that the BEFIE test is a valuable tool to detect peripheral visual field defects when standard conventional perimetry cannot be performed in young or neurologically impaired children

Perimetry in young and neurologically impaired children : The Behavioral Visual Field (BEFIE) Screening Test revisited

IMPORTANCE: Visual field examination in young or neurologically impaired children is a challenge. As a result, the Behavioral Visual Field (BEFIE) Screening Test was developed in 1995. OBJECTIVES: To evaluate the applicability of the BEFIE test in a large population of young or neurologically impaired children, its reliability and consistency of findings across time, and its potential diagnostic value compared with standard conventional perimetry. DESIGN, SETTING, AND PARTICIPANTS: The BEFIE tests were performed at an academic tertiary center and measured the peripheral visual field extension in degrees by observing an individual's response to a stimulus on a graded arc that moved from the periphery to the center of the visual field along different meridians. Patient files from all children who underwent this test were retrospectively analyzed. In total, 1788 BEFIE tests were performed in 835 children (median age, 3.4 years). MAIN OUTCOMES AND MEASURES: Reliability and results of all tests were longitudinally evaluated. The diagnostic value of the BEFIE test was assessed by comparing monocular BEFIE test results with those of standard conventional perimetry in children who underwent both. RESULTS: Of 1788 tests, 74% (95% CI, 72%-76%) were considered reliable from the age of 4 months and older, with increasing success with higher ages; 56% reliable in children younger than 1 year; 71% reliable in children between 1 and 2 years; and more than 75% reliable in children 2 years and older (Spearman r = 0.506; P = .11). Peripheral visual field defects were found in 28% (95% CI, 25%-31%) of all first reliable tests. In 75% of children who underwent serial testing, results were consistent and there were good explanations in the case of discrepancies. Comparison of monocular BEFIE tests with standard conventional perimetry results in 147 eyes yielded a positive predictive value of 98% (95% CI, 94%-100%), negative predictive value of 66% (95% CI, 56%-75%), specificity of 98% (95% CI, 95%-100%), sensitivity of 60% (95% CI, 50%-71%), and superior sensitivity of 80% (95% CI, 70%-91%) when only absolute peripheral visual field defects at standard conventional perimetry were accounted for. CONCLUSIONS AND RELEVANCE: These data suggest that the BEFIE test is a valuable tool to detect peripheral visual field defects when standard conventional perimetry cannot be performed in young or neurologically impaired children

Prediction of visual field defects in newborn infants with perinatal arterial ischemic stroke using early MRI and DTI-based tractography of the optic radiation

Purpose Visual field (VF) defects are common sequelae of perinatal arterial ischemic stroke (PAIS). The aim of this study was to investigate the predictive value of magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) for VF defects following PAIS. Methods Nineteen infants with unilateral PAIS, who underwent conventional MRI (T1/T2) and DTI at three months of age and a VF examination later in life (median age 3.2 yrs) were included. Conventional T1-weighted MRI was used to assess asymmetry of the optic radiation (OR). DTI-based tractography of the bilateral OR was performed, and the average fractional anisotropy (FA), axial (λ1), radial (λ23) and mean diffusivity (MD) were extracted. Asymmetry of the OR on MRI and DTI was used as a predictor of VF defects using receiver operating characteristic (ROC) analysis. Results Of the 19 infants, nine had a normal VF, eight had a VF defect (six hemianopia and two quadrantanopia), and two had an inconclusive VF test. The presence or absence of a VF defect could be correctly predicted using conventional MRI assessment in the majority of the infants, with an area under the curve (AUC) of 0.90 (95% CI 0.66-0.99). Prediction based on DTI parameter asymmetry indices showed an AUC of 0.96 (95% CI 0.74-1.00), 0.78 (95% CI 0.52-0.94), 0.93 (95% CI 0.70-1.00) and 0.90 (95% CI 0.66-0.99) for FA, λ1, λ23 and MD, respectively. Conclusions VF defects following PAIS can be reliably predicted by assessment of asymmetry of the OR at three months on conventional MRI and DTI-based tractography with comparable predictive values. Conventional T1-weighted MRI can be used in clinical practice

Prediction of visual field defects in newborn infants with perinatal arterial ischemic stroke using early MRI and DTI-based tractography of the optic radiation

Purpose Visual field (VF) defects are common sequelae of perinatal arterial ischemic stroke (PAIS). The aim of this study was to investigate the predictive value of magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) for VF defects following PAIS. Methods Nineteen infants with unilateral PAIS, who underwent conventional MRI (T1/T2) and DTI at three months of age and a VF examination later in life (median age 3.2 yrs) were included. Conventional T1-weighted MRI was used to assess asymmetry of the optic radiation (OR). DTI-based tractography of the bilateral OR was performed, and the average fractional anisotropy (FA), axial (λ1), radial (λ23) and mean diffusivity (MD) were extracted. Asymmetry of the OR on MRI and DTI was used as a predictor of VF defects using receiver operating characteristic (ROC) analysis. Results Of the 19 infants, nine had a normal VF, eight had a VF defect (six hemianopia and two quadrantanopia), and two had an inconclusive VF test. The presence or absence of a VF defect could be correctly predicted using conventional MRI assessment in the majority of the infants, with an area under the curve (AUC) of 0.90 (95% CI 0.66-0.99). Prediction based on DTI parameter asymmetry indices showed an AUC of 0.96 (95% CI 0.74-1.00), 0.78 (95% CI 0.52-0.94), 0.93 (95% CI 0.70-1.00) and 0.90 (95% CI 0.66-0.99) for FA, λ1, λ23 and MD, respectively. Conclusions VF defects following PAIS can be reliably predicted by assessment of asymmetry of the OR at three months on conventional MRI and DTI-based tractography with comparable predictive values. Conventional T1-weighted MRI can be used in clinical practice