Evaluating the Utility of a Postprocessing Algorithm for MRI Evaluation of Optic Neuritis.

BACKGROUND AND PURPOSE: MR imaging is useful for the detection and/or confirmation of optic neuritis. The objective of this study was to determine whether a postprocessing algorithm selectively increases the contrast-to-noise ratio of abnormal optic nerves in optic neuritis, facilitating this diagnosis on MR imaging. MATERIALS AND METHODS: In this retrospective case-control study, coronal FLAIR images and coronal contrast-enhanced T1WI from 44 patients (31 eyes with clinically confirmed optic neuritis and 28 control eyes) underwent processing using a proprietary postprocessing algorithm designed to detect and visually highlight regions of contiguous increases in signal intensity by increasing the signal intensities of regions that exceed a predetermined threshold. For quantitative evaluation of the effect on image processing, the contrast-to-noise ratio of equivalent ROIs and the contrast-to-noise ratio between optic nerves and normal-appearing white matter were measured on baseline and processed images. The effect of image-processing on diagnostic performance was evaluated by masked reviews of baseline and processed images by 6 readers with varying experience levels. RESULTS: In abnormal nerves, processing resulted in an increase in the median contrast-to-noise ratio from 17.8 to 85.0 (P < .001) on FLAIR and from 19.4 to 93.7 (P < .001) on contrast-enhanced images. The contrast-to-noise ratio for control optic nerves was not affected by processing (P = 0.13). Image processing had a beneficial effect on radiologists' diagnostic performance, with an improvement in sensitivities for 5/6 readers and relatively unchanged specificities. Interobserver agreement improved following processing. CONCLUSIONS: Processing resulted in a selective increase in the contrast-to-noise ratio for diseased nerves and corresponding improvement in the detection of optic neuritis on MR imaging by radiologists.

Clinical, genetic, and biochemical characterization of a Leber hereditary optic neuropathy family containing both the 11778 and 14484 primary mutations.

Four mitochondrial DNA (mtDNA) mutations at nps 3460, 11778, 14484, and 14459 account for roughly 90% of cases of Leber hereditary optic neuropathy (LHON) and are designated as "primary" LHON mutations since they act as major predisposition factors for LHON. Although each primary mutation can arise independently on different mtDNA backgrounds during human evolution, they characteristically do not co-occur in LHON patients. We report here a family with the simultaneous occurrence of the 11778A and 14484C mutations. Neuro-ophthalmological examination of the proband, a nine-year-old Caucasian female, revealed the bilateral optic atrophy, central scotomas, and reduced visual acuity typical of LHON. Her mother had normal appearing optic discs and is today visually asymptomatic. Analysis of the proband blood mtDNA revealed that she harbored both the 11778A (heteroplasmic, 94% mutant) and the 14484C (homoplasmic mutant) mutation. This genotype was maintained in proband lymphoblasts and transmitochondrial cybrids. The mother also had both mutations, with the 14484C mutation homoplasmic in all cell types examined. However, only 31% of her blood mtDNAs carried the 11778 mutation, which segregated to essentially 100% wild-type in lymphoblast and cybrid mtDNA. Complex I-linked respiration and specific enzyme activity were consistently lowest in proband lymphoblast and cybrid mitochondria compared to those from the mother, 11778A patients, 14484C patients, or controls, thus demonstrating both a deleterious synergistic interaction between the 11778A and 14484C mutations and the magnitude of 11778A-associated complex I dysfunction. Remarkably, spontaneous vision recovery occurred in the proband, highlighting the complexities encountered when associating mtDNA genotype and complex I function with LHON expression.

Optic neuropathies. An overview.

A diverse group of pathologic processes may affect the optic nerve. Clinical manifestations allow localization of pathology to the optic nerve and suggest possible etiologies. Optic disc edema and optic atrophy are fundoscopically visible signs of optic nerve pathology and may provide clues to the underlying process. Hereditary, toxic, nutritional, and compressive optic neuropathies often have characteristic clinical findings that may provide clues to a possible diagnosis.

Atypical idiopathic intracranial hypertension: normal BMI and older patients.

BACKGROUND: Idiopathic intracranial hypertension (IIH) typically affects young, obese women. We examined 2 groups of atypical patients with IIH: those with a normal body mass index (BMI) and those at least 50 years of age. METHODS: A retrospective cohort study of 407 consecutive adult patients with IIH with known BMI from 3 centers was undertaken. Demographics, associated factors, visual acuity, and visual fields were collected at presentation and follow-up. RESULTS: We identified 18 IIH patients (4%) with normal BMI and 19 (5%) aged 50 years or older at the time of diagnosis who were compared with the remainder of the cohort. Medication-induced IIH was more frequent in patients with IIH with normal BMI (28 vs 7%, p = 0.008). No patient with IIH with a normal BMI had severe visual loss in either eye (0 vs 17%, p = 0.09). Older patients with IIH had a lower BMI, but were still generally obese (33 vs 38, p = 0.04). Older patients were less likely to report headache as initial symptom (37 vs 76%, p < 0.001) and more likely to complain of visual changes (42 vs 21%, p = 0.03). Treatment of any type was less likely in older patients (significant for medications: 74 vs 91%, p = 0.004), and they were more likely to have persistent disc edema at last follow-up (median Frisén grade: 1 vs 0, p = 0.002), but had similar, if not better, visual outcomes compared with younger patients. A case-control study did not identify any new medication or risk factor associations. CONCLUSIONS: Patients with normal body mass index and those 50 years or older make up a small proportion of patients with idiopathic intracranial hypertension (IIH), but appear to have better visual outcomes than more typical patients with IIH.

Idiopathic intracranial hypertension in men.

OBJECTIVE: To compare the characteristics of idiopathic intracranial hypertension (IIH) in men vs women in a multicenter study. METHODS: Medical records of all consecutive patients with definite IIH seen at three university hospitals were reviewed. Demographics, associated factors, and visual function at presentation and follow-up were collected. Patients were divided into two groups based on sex for statistical comparisons. RESULTS: We included 721 consecutive patients, including 66 men (9%) and 655 women (91%). Men were more likely to have sleep apnea (24% vs 4%, p < 0.001) and were older (37 vs 28 years, p = 0.02). As their first symptom of IIH, men were less likely to report headache (55% vs 75%, p < 0.001) but more likely to report visual disturbances (35% vs 20%, p = 0.005). Men continued to have less headache (79% vs 89%, p = 0.01) at initial neuro-ophthalmologic assessment. Visual acuity and visual fields at presentation and last follow-up were significantly worse among men. The relative risk of severe visual loss for men compared with women was 2.1 (95% CI 1.4-3.3, p = 0.002) for at least one eye and 2.1 (95% CI 1.1-3.7, p = 0.03) for both eyes. Logistic regression supported sex as an independent risk factor for severe visual loss. CONCLUSION: Men with idiopathic intracranial hypertension (IIH) are twice as likely as women to develop severe visual loss. Men and women have different symptom profiles, which could represent differences in symptom expression or symptom thresholds between the sexes. Men with IIH likely need to be followed more closely regarding visual function because they may not reliably experience or report other symptoms of increased intracranial pressure.

Management of optic neuritis and multiple sclerosis.

Optic neuritis and multiple sclerosis (MS) are common causes of visual and neurologic dysfunction in young adults. Advances in magnetic resonance imaging, molecular genetics, and neuroimmunology have increased our understanding of the pathophysiology underlying both disorders. Corticosteroids remain the mainstay of treatment of optic neuritis, but alternate dosages and routes of administration are undergoing investigation. The available therapies for MS have expanded, and there is evidence that early intervention is beneficial. Treatments for MS show sustained efficacy, but are not curative, and adjunctive treatments may prove valuable in patients with progressive visual and neurologic disability.

Neuro-ophthalmic manifestations of head trauma.

OBJECTIVE: To describe the neuro-ophthalmic findings in a group of patients with head trauma. MATERIALS AND METHODS: A retrospective chart review of all patients given a diagnosis code of head trauma in the neuroophthalmology unit at Emory University between 1991 and 1999. RESULTS: A total of 326 consecutive patients were reviewed (203 [63%] men and 123 [37.0%] women). Age ranged from 2 to 86 years, with a mean of 30 years. Motor vehicle accident was the most common cause of head trauma, occurring in 195 (59.8%) patients. An abnormal neuro-ophthalmic examination was noted in 185 of 326 patients (56.7%). Loss of consciousness was not associated with any outcome, but the presence of a neuroimaging abnormality, particularly intracranial hemorrhage, was significantly associated with specific neuroophthalmic deficits. CONCLUSIONS: Head trauma causes a number of neuroophthalmic manifestations. The afferent and efferent pathways are vulnerable to traumatic injury, although the efferent system is more commonly affected. Loss of consciousness may not be a reliable predictor of specific neuro-ophthalmic outcomes, but neuroimaging abnormalities may.