Pediatric optic nerve and optic nerve sheath diameter on magnetic resonance imaging.

BACKGROUND: The normal values of optic nerve diameter and optic nerve sheath diameter might be beneficial in defining an abnormality such as optic nerve hypoplasia, or enlarged subarachnoid space, reflecting the state of increased intracranial pressure. OBJECTIVE: To study the normal optic nerve diameter and optic nerve sheath diameter on magnetic resonance imaging (MRI) in the early years of postnatal visual development from MRI of the brain. MATERIALS AND METHODS: MRI of the brain in patients ages 4 years and younger were gathered. Forty-two studies with normal intracranial findings and a lack of history of increased intracranial pressure were retrospectively reviewed by two reviewers using axial T2-weighted images. Measurements were performed in transverse diameter perpendicular to the optic nerve at 3 mm behind the globe. RESULTS: The mean optic nerve diameter of the 77 optic nerves were 2.5 mm (95% confidence interval [CI] 2.4-2.6). The mean optic nerve sheath diameter values of the 79 optic nerve sheath complexes were 5.0 mm (95% CI 4.9-5.1). The mean±standard deviation optic nerve diameter and optic nerve sheath diameter stratified by each age groups were, respectively, 0 to <1 year: 2.3±0.40 and 4.81±0.37; 1 to <2 years: 2.6±0.2 and 5.0±0.4; 2 to <3 years: 2.4±0.3 and 4.9±0.6, and 3 to <4 years: 2.9±0.4 and 5.2±0.60 mm. CONCLUSION: Seventy-four of the 77 measurements (96%) were of the measurements were above the threshold of 2 mm for optic nerve diameter. Seventy-seven of the 79 measurements (97%) were of the measurements were below the threshold of 6 mm for optic nerve sheath diameter.

Incidence of Associated Brain and Ophthalmic Anomalies in Frontoethmoidal Encephalomeningocele Evaluated by Multidetector Computed Tomography Facial Bone Imaging.

INTRODUCTION: Frontoethmoidal encephalomeningocele (FEEM) is a congenital disorder characterized by herniation of brain and meninges through an anterior skull defect. The main pathological changes are found internally at the foramen cecum and externally at the frontonaso-orbital region. The aim of this study was to determine the incidence of developmental anomalies found in FEEM using multidetector computed tomography images of the facial bone. METHODS: A total of 78 patients who underwent multidetector computed tomography scan of the facial bone during the January 1, 2003 to June 31, 2012 study period were retrospectively reviewed. Demographic data, size of internal defect, and intracranial anomalies were recorded. RESULTS: Associated brain and ophthalmic anomalies were identified in 53 patients (67.9%), and all of those had brain anomalies. The most common brain anomalies were absent/undetermined septum pellucidum (75.5%), ventricular dilatation (71.7%), abnormal frontal horn (67.9%), and dysgenesis of the corpus callosum (58.5%). Eight patients (10.3%) had ophthalmic anomalies. Patients with brain and ophthalmic anomalies tended to have a higher incidence of large-size internal defects. CONCLUSION: The authors found a high prevalence of developmental anomalies in FEEM patients. Absent/undetermined septum pellucidum was the most commonly found anomaly in this study. Brain and ophthalmic anomalies tended to have a higher incidence of large-size internal bone defects. Consistent with the authors' acknowledged limitation, further studies using dedicated brain MRI and magnetic resonance angiography to evaluate parenchymal abnormalities and vascular anomalies may be beneficial for surgical planning, prognosis, and the identification of clinical correlations.