Prognostic value of magnetic resonance imaging in monosymptomatic optic neuritis

Radiologic Predictors of Visual Outcome in Myelin Oligodendrocyte Glycoprotein-Related Optic Neuritis

PURPOSE

This study aimed to determine whether magnetic resonance imaging (MRI) biomarkers are associated with visual prognosis in myelin oligodendrocyte protein (MOG)-associated optic neuritis (ON).

DESIGN

Cross-sectional analysis.

PARTICIPANTS

Patients meeting 2023 international diagnostic criteria for MOG antibody-associated disease who were seen for first episodes of MOG-associated ON at 3 tertiary neuro-ophthalmology practices between January 2017 and July 2023 were enrolled. Patients who received < 3 months of neuro-ophthalmic follow-up and did not demonstrate visual recovery (visual acuity [VA] ≥ 20/20 and visual field mean deviation [VFMD] > -5.0 dB) during this time were excluded.

METHODS

Patients underwent contrast-enhanced, fat-suppressed MRI of the brain and orbits within 1 month of symptom onset.

MAIN OUTCOME MEASURES

The associations between radiologic biomarkers and poor VA outcome (< 20/40), incomplete VA recovery (< 20/20), and poor VFMD outcome (VFMD < -5.0 dB) were assessed using multivariable logistic regression adjusting for time from symptom onset to treatment and nadir VA or VFMD. Radiologic biomarkers included length of optic nerve enhancement (> 25% vs. < 25%; > 50% vs. < 50%; and > 75% vs. < 75%); degree of orbital, canalicular, and intracranial or chiasmal optic nerve enhancement (mild vs. moderate to severe compared with the lacrimal gland); and absence versus presence of optic nerve sheath enhancement on baseline T1-weighted MRI.

RESULTS

A total of 129 eyes of 92 patients (median age, 37.0 years [interquartile range, 20.8-51.3 years]; 65.2% female) were included. Poor VA outcome was seen in 6.2% of patients, incomplete VA recovery was seen in 19.4% of patients, and poor VFMD outcome was seen in 16.9% of patients. Compared with eyes with moderate to severe enhancement, eyes with mild orbital optic nerve enhancement were more likely to have poor VA outcome (odds ratio [OR], 8.57; 95% confidence interval [CI], 1.85-51.14; P = 0.009), incomplete VA recovery (OR, 7.31, 95% CI, 2.42-25.47; P = 0.001), and poor VFMD outcome (adjusting for time to treatment: OR, 6.81; 95% CI, 1.85-28.98; P = 0.005; adjusting for nadir VFMD: OR, 11.65; 95% CI, 1.60-240.09; P = 0.04). Lack of optic nerve sheath enhancement additionally was associated with incomplete VA recovery (OR, 3.86; 95% CI, 1.19-12.85; P = 0.02) compared with the presence of enhancement. These associations remained consistent in subgroup logistic regression analysis of MRIs performed before initiation of treatment but were not seen in pairwise analysis of MRIs performed after treatment.

CONCLUSIONS

In eyes with first MOG-associated ON episodes, milder enhancement in the orbital optic nerve was associated with poorer VA and visual field recovery. Prospective and mechanistic studies are needed to confirm the prognostic usefulness of MRI in MOG-associated ON.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Analysis of the initial orbital MRI in aquaporin-4 antibody-positive optic neuritis (AQP4-ON): lesion location and lesion length can be predictive of visual prognosis

PURPOSE

Despite mounting evidence indicating that aquaporin-4 antibody-positive optic neuritis (AQP4-ON) presents a less favorable prognosis than other types of optic neuritis, there exists substantial heterogeneity in the prognostic outcomes within the AQP4-ON cohort. Considering the persistent debate over the role of MRI in assessing the prognosis of optic neuritis, we aim to investigate the correlation between the MRI appearance and long-term visual prognosis in AQP4-ON patients.

METHODS

We retrospectively reviewed the ophthalmological and imaging data of AQP4-ON patients admitted to our Neuro-ophthalmology Department from January 2015 to March 2018, with consecutive follow-up visits for a minimum of 3 years.

RESULTS

A total of 51 AQP4-ON patients (59 eyes) meeting the criteria were enrolled in this research. After assessing the initial orbital MR images of each patient at the first onset, we observed the involvement of the canalicular segment (p < 0.001), intracranial segment (p = 0.004), optic chiasm (p = 0.009), and the presence of LEON (p = 0.002) were significantly different between recovery group and impairment group. For quantitative measurement, the length of the lesions is significantly higher in the impairment group (20.1 ± 9.3 mm) than in the recovery group (12.5 ± 5.3 mm) (p = 0.001).

CONCLUSION

AQP4-ON patients with involvement of canalicular, intracranial segment and optic chiasm of the optic nerve, and the longer range of lesions threaten worse vision prognoses. Timely MR examination during the initial acute phase can not only exclude the intracranial or orbital mass lesions but also indicate visual prognosis in the long term.

Poor Visual Outcome After First Attack in a Cohort of Patients With Myelin Oligodendrocyte Glycoprotein-Related Optic Neuritis

BACKGROUND

Myelin oligodendrocyte glycoprotein-associated optic neuritis (MOG-ON) is typically a highly treatable condition that responds quickly to treatment with high doses of corticosteroids. We reviewed the cohort of patients with MOG-ON to identify patients who had poor visual outcome after the first attack despite rapid initiation of treatment.

METHODS

Records of all patients diagnosed with MOG-ON seen in a tertiary neuro-ophthalmology practice were reviewed to identify and describe those with poor visual recovery (final visual acuity of 20/200 or worse in at least one eye) after the first attack despite initiation of treatment within 1 week of symptoms onset.

RESULTS

Two patients of 36 fulfilled inclusion criteria: both had bilateral severe optic neuritis at presentation, and both were seen within 7 days of symptoms onset and treated immediately with pulse doses of intravenous corticosteroids followed by very-slow oral taper. Plasma exchange (PLEX) was performed 2 weeks after symptoms onset in both patients because of poor response to steroids, followed by monthly intravenous immunoglobulin infusions. Despite the use of all available treatment modalities, final visual outcome was poor in both patients. In both patients, there was enhancement of intracanalicular portion of optic nerve in the worse-seeing eye.

CONCLUSIONS

In this cohort of patients with MOG-ON, 2 (5.6%) had very poor visual outcome after the first attack despite immediate initiation of treatment with pulse doses of corticosteroids and subsequent treatment with PLEX. These cases highlight that despite immediate initiation and escalation of treatment, some patients with MOG-ON can have very poor visual outcomes after the initial attack that may be because of the involvement of the intracanalicular portion of the optic nerves.

Syphilitic Uveitis With Diverse Clinical Presentations: Multimodal Imaging as a Useful Adjunctive Tool for Diagnosis and Treatment

We report four cases of syphilitic uveitis with diverse clinical presentations. All patients were men who have sex with women, and were aged 19-68 years, and none were HIV-positive. All cases were bilateral. One case presented with anterior uveitis, while three exhibited panuveitis. One patient had acute syphilitic posterior placoid chorioretinitis and two had retinal vasculitis resulting in damage to the outer retinal and retinal pigment epithelium. The rapid plasma reagin (RPR) test and Treponema pallidum (TP) hemagglutination test were both positive in all cases. Six of eight eyes had improved vision and best-corrected visual acuity better than 20/20 after antibiotic treatment. Serological testing is mandatory for the diagnosis of syphilitic uveitis. Additionally, multimodal imaging, including optical coherence tomography (OCT), fundus autofluorescence (FAF), and fluorescein angiography (FA), can provide useful adjunctive information for early diagnosis and assessment of treatment response.

Assessing the Correlation Between Visual Acuity and Critical Fusion Frequency in Acute Optic Neuritis Before and After Steroid Therapy

Background Optic nerve diseases include inflammatory optic nerve diseases such as vasculitis, metabolic optic neuropathy, ischemic optic neuropathy, and optic neuritis. In this study, patients with acute optic neuritis are classified with better and poor visual acuity based on visual acuity after one month of steroid pulse therapy. To determine prognosis, initial visual acuity and critical fusion frequency (CFF) values will be compared with those recorded one month after treatment and at the last visit. Methods Visual acuity and CFF were evaluated one month after the start of treatment in patients diagnosed with acute optic neuritis, and follow-up was available for at least three months at Hiroshima University Hospital. Results All patients received steroid pulse therapy as initial treatment. After one month of treatment, visual acuity and CFF at the last visit were significantly improved in the group with improved visual acuity compared to the group with impaired visual acuity. Conclusions Visual acuity at the initial visit did not affect treatment outcome, and final visual acuity and CFF after one month of treatment for acute optic neuritis were better in patients with better visual acuity. Therefore, visual acuity values one month after treatment initiation may affect treatment outcomes.

Clinical and diagnostic spectrum of optic neuritis: A single-center retrospective study of disorders associated with multiple sclerosis, anti-aquaporin-4 and anti-myelin oligodendrocyte glycoprotein antibodies

OBJECTIVE

Optic neuritis (ON) is an immune-mediated optic neuropathy associated with multiple immune-mediated neurological conditions. Our aim was to characterize the clinical and diagnostic features of first or initial episodes of ON associated with multiple sclerosis (MS)-associated (typical) and antibody-related (atypical) ON.

METHODS

Retrospective, single institution, medical record review. We analyzed demographic, clinical, laboratory, and radiographic findings of 139 patients who presented with first episodes of MS-associated ON (MS-ON), aquaporin 4 antibody-associated ON (AQP4-ON), and myelin oligodendrocyte glycoprotein antibody-associated ON (MOG-ON) between January 2015 and October 2019 without preceding diagnosis. Simple hypothesis testing assessed differences between groups were performed.

RESULTS

Of 139 patients (109 [79 %] women; 29 [21 %] men; mean age 47 [SD, 14] years), 106 had MS-ON, 25 had AQP4-ON, and 8 had MOG-ON. Patients with MOG-ON had the highest recurrence rate (88 %) relative to MS-ON (28 %) and AQP4-ON (56 %) patients (P < .001). Patients with AQP4-ON had the highest mean visual functional system scores (4.3 [SD, 1.8]) relative to MS-ON (2.0 [SD, 1.9]) and MOG-ON patients (2.8 [SD, 2.0]) (P < .001).

CONCLUSION

Patients presenting with initial episodes of ON exhibit a range radiographic and laboratory feature depending on the underlying associated disease. Understanding the variable characteristics of typical (MS-associated) and atypical (antibody-associated) ON may help physicians accurately diagnose and effectively treat ON.

Optic Nerve Lesion Length at the Acute Phase of Optic Neuritis Is Predictive of Retinal Neuronal Loss

Background and Objectives

Acute optic neuritis (ON) is a classical presenting symptom of multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), and anti–MOG-associated disorders. The resulting visual impairment is variable and can be severe. Clinicians are in need of predictive biomarkers to optimize the management of acute ON. In this longitudinal study (IRMANO, NCT03651662), we evaluated the ability of optic nerve lesion length measured on MRI at the acute phase of ON to predict retinal neuro-axonal loss and visual impairment at a chronic stage.

Methods

We conducted a longitudinal study (IRMANO, NCT03651662) of patients who presented a clinical episode of ON (≤8 weeks). All patients underwent a retinal optical coherence tomography (OCT) and a brain/optic nerve MRI, including 3D double-inversion recovery (DIR) sequence at the acute phase of ON and 12 months later. Primary outcomes were optic nerve DIR hypersignal lesion length, macular ganglion cell–inner plexiform layer (GCIPL) volume measured on OCT, and low-contrast monocular visual acuity (LCMVA).

Results

The study group included 51 patients (33 women, mean age of 32.4 years ± 7.9). We recruited patients with a clinically isolated syndrome (n = 20), a relapsing-remitting MS (n = 23), an isolated ON (n = 6), and a first clinical episode of NMOSD (n = 2). Optic nerve DIR hypersignal was observed in all but 1 symptomatic optic nerves. At inclusion, the mean optic nerve lesion length (in mm) was 12.35 ± 5.98. The mean GCIPL volume (in mm³) significantly decreased between inclusion (1.90 ± 0.18) and M₁₂ (1.67 ± 0.21; p < 0.0001). Optic nerve lesion length at inclusion was significantly associated with GCIPL thinning (estimate ± SD; −0.012 ± 0.004; p = 0.0016) and LCMVA at M₁₂ (0.016 ± 0.003; p < 0.001). Optic nerve lesion length significantly increased at M₁₂ (15.76 ± 8.70; p = 0.0007). The increase in optic nerve lesion length was significantly associated with the GCIPL thinning between inclusion and M₁₂ (−0.012 ± 0.003; p = 0.0011).

Discussion

At the acute phase of ON, optic nerve lesion length is an imaging biomarker predictive of retinal neuro-axonal loss and chronic visual impairment, which can help to stratify future therapeutic strategies in acute ON.

Classification of Evidence

This study provides Class I evidence that optic nerve lesion length measured on MRI during the acute phase of a first episode of ON is associated with long-term retinal neuro-axonal loss and visual impairment.

MRI Characteristics of NMO, MOG and MS Related Optic Neuritis

Acute isolated optic neuritis can be the initial presentation of demyelinating inflammatory central nervous system disease related to multiple sclerosis (MS), neuromyelitis optica (NMO) or myelin oligodendrocyte glycoprotein antibody disease (MOG-AD). In addition to the well-characterized brain and spinal cord imaging features, important and characteristic differences in the radiologic appearance of the optic nerves in these disorders are being described, and magnetic resonance imaging (MRI) of the optic nerves is becoming an essential tool in the differential diagnosis of optic neuritis. Whereas typical demyelinating optic neuritis is a relatively mild and self-limited disease, atypical optic neuritis in NMO and MOG-AD is potentially much more vision-threatening and merits a different treatment approach. Thus, differentiation based on MRI features may be particularly important during the first attack of optic neuritis, when antibody status is not yet known. This review discusses the optic nerve imaging in the major demyelinating disorders with an emphasis on clinically relevant differences that can help clinicians assess and manage these important neuro-ophthalmic disorders. It also reviews the utility of optic nerve MRI as a prognostic indicator in acute optic neuritis.

Optical coherence tomography: a window to the optic nerve in clinically isolated syndrome

In this study, we aimed to evaluate the association of asymptomatic optic nerve demyelinating lesion in patients presenting a clinically isolated syndrome with the asymptomatic retinal neuro-axonal loss previously reported at clinically isolated syndrome. We prospectively recruited 66 patients presenting a clinically isolated syndrome and 66 healthy control subjects matched according to age and gender. All patients underwent brain magnetic resonance imaging including 3D-double inversion recovery (DIR) sequence, optical coherence tomography examination and visual function evaluation, at 2.5-4.5 months after CIS. Evaluation criteria were presence and length of optic nerve DIR hypersignal, retinal layers (including ganglion cell inner plexiform layer and inner nuclear layer) thickness/volume, and low contrast monocular vision acuity (number of letters correctly identified). All clinically isolated syndrome eyes with past history of optic neuritis (CIS-ON) presented an optic nerve DIR hypersignal. We observed asymptomatic optic nerve DIR hypersignal in 22.2% of clinically isolated syndrome eyes without optic neuritis (CIS-NON). In comparison with healthy control, GCIPL volume (in mm3) was significantly lower in CIS-ON eyes [β (95% confidence interval, CI) = -0.121 (-0.168 to -0.074); P < 0.0001], and to a lesser extent in CIS-NON [β (95% CI) = -0.023 (-0.039 to -0.008); P = 0.004]. In comparison to healthy controls, eyes with asymptomatic optic nerve DIR hypersignal presented significantly lower macular ganglion cell inner plexiform layer volume [β (95% CI) = -0.043 (-0.068 to -0.019); P = 0.001], and eyes without did not [β (95% CI) = -0.016 (-0.034 to 0.003); P = 0.083]. Among CIS-NON, macular ganglion cell inner plexiform layer volume decrease was associated with asymptomatic optic nerve DIR hypersignal independently of optic radiations T2 lesions and primary visual cortex volumes (P = 0.012). Symptomatic optic nerve DIR hypersignal were significantly longer (13.8 ± 6.7 mm) than asymptomatic optic nerve hypersignal (10.0 ± 5.5 mm; P = 0.047). Length of optic nerve DIR hypersignal was significantly associated with thinner inner retinal layers (P ≤ 0.001), thicker inner nuclear layer (P = 0.017) and lower low contrast monocular vision acuity (P < 0.05). Compared to healthy control, low contrast monocular vision acuity was significantly lower in CIS-ON eyes (P < 0.0001) and CIS-NON eyes with (P = 0.03) or without asymptomatic optic nerve DIR hypersignal (P = 0.0005). Asymptomatic demyelinating optic nerve DIR hypersignal at the earliest clinical stage of multiple sclerosis is frequent and associated with asymptomatic retinal neuro-axonal loss reported at clinically isolated syndrome stage. Length of optic nerve DIR hypersignal is a biomarker of retinal neuro-axonal loss and visual disability at clinically isolated syndrome stage. Visual disability of clinically isolated syndrome eyes without clinical and subclinical optic nerve involvement might be due to missed optic nerve lesions on MRI. At the earliest clinical stage of multiple sclerosis, our results support considering optical coherence tomography as a window to the optic nerve rather than to the brain.

Radiomics Analysis of DTI Data to Assess Vision Outcome After Intravenous Methylprednisolone Therapy in Neuromyelitis Optic Neuritis

BACKGROUND

Neuromyelitis optica-optic neuritis (NMO-ON) patients are routinely treated with intravenous methylprednisolone (IVMP). For the patients nonresponsive to IVMP, more effective but aggressive therapy of plasma exchange (PE) should be employed instead of IVMP in the first line.

PURPOSE

To assess the visual outcomes of NMO-ON patients after IVMP by radiomics analysis of whole brain diffusion tensor imaging (DTI) data.

STUDY TYPE

Retrospective.

POPULATION

In all, 57 NMO-ON patients receiving IVMP therapy for 3 days.

FIELD STRENGTH/SEQUENCE

3.0T; DTI images acquired by a single-shot echo planar image sequence; T₁ images acquired by 3D fast spoiled gradient echo (3D-FSPGR) MRI.

ASSESSMENT

In all, 200 DTI measures were extracted from the DTI data and employed as features to construct a radiomics assessment model for visual outcomes of NMO-ON patients after IVMP. The assessment performance was evaluated by area under the receiver operating characteristic curve (AUC), classification accuracy (ACC), sensitivity, specificity, and positive and negative predicted values (PPV and NPV). The selected DTI measures would reveal the white matter impairments related to visual recovery of NMO-ON patients.

STATISTICAL TESTS

The relationship between the selected DTI measures and the clinical visual characteristics were investigated by Pearson correlation, Spearman's rank correlation, and one-way analysis of variance analysis.

RESULTS

The radiomics model obtained an ACC of 73.68% (P = 0.002), AUC of 0.7931, sensitivity of 0.6207, specificity of 0.8571, PPV of 0.8182, and NPV of 0.6857 in assessing visual outcomes of the NMO-ON patients after IVMP treatment. The selected DTI measures revealed white matter impairments related to the visual outcomes in the white matter tracts of vision-relevant regions, motor-related regions, and corpus callosum. The white matter impairments were found significantly correlated with the disease duration and the length of lesions in the optic nerve.

DATA CONCLUSION

Radiomics analysis of DTI data has great potential in assessing visual outcomes of NMO-ON patients after IVMP therapy.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2019;49:1365-1373.

Length of optic nerve double inversion recovery hypersignal is associated with retinal axonal loss

OBJECTIVES

To assess the association between optic nerve double inversion recovery (DIR) hypersignal length and retinal axonal loss in neuroinflammatory diseases affecting optic nerves.

METHODS

We recruited patients previously affected (> 6 months) by a clinical episode of optic neuritis (ON). We had 25 multiple sclerosis (MS) patients, eight neuromyelitis optica spectrum disorder (NMOSD) patients and two patients suffering from idiopathic caused ON undergo brain magnetic resonance imaging (MRI); including a 3-dimensional (3D) DIR sequence, optical coherence tomography (OCT) examination and visual disability evaluation. Evaluation criteria were retinal thickness/volume, optic nerve DIR hypersignal length and high/low contrast vision acuity.

RESULTS

In the whole cohort, we found good associations (< 0.0001) between optic nerve DIR hypersignal length, peripapillary retinal nerve fiber layer thickness, inner macular layers volumes, and visual disability. We found subclinical radiological optic nerve involvement in 38.5% of non-ON MS eyes.

CONCLUSIONS

Optic nerve DIR hypersignal length may be a biomarker for retinal axonal loss, easily applicable in routine and research on new anti-inflammatory or neuroprotective drug evaluation. Detection of subclinical ON with 3D-DIR in a non-negligible proportion of MS patients argues in favor of optic nerve imaging in future OCT MS studies, in order to achieve a better understanding of retinal axonal loss in non-ON eyes.

Imaging of Optic Neuropathy and Chiasmal Syndromes

Optic neuropathy involves loss of visual acuity, color vision, and visual field defect with a swollen, pale, anomalous, or normal optic disc seen on fundoscopy. Chiasmal disorders classically present with gradual onset of vision loss, bitemporal hemianopsia, and occasionally, endocrinopathy if the pituitary gland and/or hypothalamus are the causes or are involved. Advance in neuroimaging, especially magnetic resonance (MR) imaging, can reveal pathologic conditions previously detected only clinically. Some entities have imaging characteristics, leading to appropriate treatment without requiring tissue biopsies. Imaging also provides disease surveillance and posttreatment assessment, with computed tomography and MR imaging being complementary to each other.

Baseline magnetic resonance imaging of the optic nerve provides limited predictive information on short-term recovery after acute optic neuritis

Background

In acute optic neuritis, magnetic resonance imaging (MRI) may help to confirm the diagnosis as well as to exclude alternative diagnoses. Yet, little is known on the value of optic nerve imaging for predicting clinical symptoms or therapeutic outcome.

Purpose

To evaluate the benefit of optic nerve MRI for predicting response to appropriate therapy and recovery of visual acuity.

Methods

Clinical data as well as visual evoked potentials (VEP) and MRI results of 104 patients, who were treated at the Department of Neurology with clinically definite optic neuritis between December 2010 and September 2012 were retrospectively reviewed including a follow up within 14 days.

Results

Both length of the Gd enhancing lesion (r = -0.38; p = 0.001) and the T2 lesion (r = -0.25; p = 0.03) of the optic nerve in acute optic neuritis showed a medium correlation with visual acuity after treatment. Although visual acuity pre-treatment was little but nonsignificantly lower if Gd enhancement of the optic nerve was detected via orbital MRI, improvement of visual acuity after adequate therapy was significantly better (0.40 vs. 0.24; p = 0.04). Intraorbitally located Gd enhancing lesions were associated with worse visual improvement compared to canalicular, intracranial and chiasmal lesions (0.35 vs. 0.54; p = 0.02).

Conclusion

Orbital MRI is a broadly available, valuable tool for predicting the improvement of visual function. While the accurate individual prediction of long-term outcomes after appropriate therapy still remains difficult, lesion length of Gd enhancement and T2 lesion contribute to its prediction and a better short-term visual outcome may be associated with detection and localization of Gd enhancement along the optic nerve.

Longitudinally extensive optic neuritis in pediatric patients

Extensive optic nerve demyelinating lesions on magnetic resonance imaging (MRI) in adults could indicate a diagnosis other than multiple sclerosis with worse prognosis such as neuromyelitis optica. We report the frequency of longitudinally extensive lesions in children with first events of optic neuritis. Subjects had brain or orbit MRI within 3 months of onset and were evaluated at the University of California, San Francisco, Pediatric Multiple Sclerosis Center. Lesion length, determined by T2 hyperintensity or contrast enhancement, was blindly graded as absent, focal or longitudinally extensive (at least 2 contiguous segments of optic nerve). Of 25 subjects, 9 (36%) had longitudinally extensive optic neuritis. Extensive lesions were not associated with non-multiple sclerosis versus multiple sclerosis diagnosis (P = 1.00). No association between age and lesion extent was observed (P = .26). Prospective studies are needed to determine if longitudinally extensive optic neuritis can predict visual outcome.

The neuro-ophthalmology of multiple sclerosis

Multiple sclerosis (MS) is a disease marked by focal demyelinating inflammatory plaques throughout the CNS. Neuro-ophthalmologic sequelae are common in MS and may arise from the disease itself or from treatment of the disease. Both afferent and efferent functions may be affected. Despite much progress, our understanding of the pathophysiology of MS, and the efficacy of our available treatments, remain inadequate. Here, we review the chief neuro-ophthalmologic abnormalities associated with MS and discuss the emerging diagnostic and therapeutic advances that are likely to further our understanding of MS and its treatment.

[Inflammatory diseases of the orbit]

Inflammatory conditions belong to the most important diseases of the orbit. Children and adolescents are mostly affected and the most common cause is secondary pathogen invasion from acute sinusitis. However in adults most cases involve idiopathic orbital inflammation, previously termed pseudotumor orbitae. Clinical presentation may include painful exophthalmus, skin redness and warming, chemosis and disturbed eye motility. The challenge for imaging investigations, mainly a combination of CT scanning and MRI, is to distinguish inflammatory from malignant conditions, to define the extent of lesions and to document possible complications, such as cavernous sinus thrombosis, meningoencephalitis or cerebral abscesses. Serious potential consequences of orbital infections, including loss of vision or death, are still a risk factor and must be averted by avoidance of delays in diagnosis and appropriate clinical management.

Quantitative evaluation of signal intensity of magnetic resonance images in optic neuritis

We have evaluated the signal intensity of magnetic resonance (MR) images of the optic nerve quantitatively in 25 patients with unilateral acute optic neuritis (ON). MR imaging was performed with a 1.5 Tesla unit before treatment within 2 weeks after the onset of ON. Four coronal fat-suppressed T2-weighted images were obtained at 5, 10, 15, and 20 mm behind the eye. The ratio of the signal intensity of the MR images from the optic nerve to that of the white matter of the frontal lobe was calculated and we compared the signal intensity ratio of the affected eyes to the fellow healthy eyes. For statistical analysis paired t-test was used. At all 4 sections, the mean signal intensity ratio of the affected eyes is statistically significant higher than fellow eyes. The 11 patients showed optic disc swelling in the affected eyes and in all these 11 eyes had a higher signal intensity at 5 mm behind the eye compared with the fellow eye. From our present results, we cannot refer to the sensitivity of our method, because we did not use our present methods to other diseases. But with this method we think inter-image and inter-observer variability must reduce. Further studies are required about the sensitivity and the relation between the pathological condition of optic nerve and the signal intensity ratio.

[Multiple sclerosis. An update with practical guidelines for ophthalmologists]

Multiple sclerosis (MS) is the most frequent chronic inflammatory disease of the central nervous system. Mostly young adults present with a variety of different symptoms due to the multiple localisations of the inflammatory lesions. Up to one-third of MS patients experience symptoms of optic neuritis as the initial symptom. That is the reason why the ophthalmologist often is the first physician contacted by patients later on diagnosed with MS. Today, it is known that there is already a significant irreversible axonal loss in MS patients progressing from the beginning of the disease. Therefore early, diagnosis and application of available therapeutic options are necessary for the patient's benefit. The therapeutic aim in early immunomodulatory treatment is to decrease the number of relapses and to slow down the development of clinical disability. This interdisciplinary overview presents guidelines for the clinical routine: how to assess the individual risk of each patient and how to treat the patient in accordance with current pathogenic, diagnostic and therapeutic knowledge.

Evolving management of optic neuritis and multiple sclerosis

PURPOSE

To review the relation of optic neuritis to multiple sclerosis (MS) and the indications, modalities, and results of therapy for optic neuritis, for both visual and general neurologic function.

DESIGN

Literature review and author's experience.

METHODS

Analysis of both laboratory and clinical evidence supporting the use of corticosteroids, immunomodulation agents, and other modalities in the treatment of optic neuritis and MS.

RESULTS

Although treatment of optic neuritis with corticosteroids may hasten visual recovery to a minor degree, it has no long-term beneficial effect on visual outcome. Optic neuritis is frequently the initial manifestation of multiple sclerosis. The risk of later development of clinically definite MS (CDMS) correlates with white matter demyelinative lesions on magnetic resonance imaging (MRI). The role of corticosteroid therapy alone in reducing the risk of subsequent MS is unclear, but recent studies suggest that the combination of immunomodulation agents (IMAs) and corticosteroids significantly reduces the later development of MS. Current research indicates that, contrary to previous doctrine, axonal damage is an early finding in MS.

CONCLUSIONS

The risk of MS after optic neuritis may be predicted. The use of corticosteroids and IMAs, particularly in those at substantial risk, reduces the frequency and severity of developing CDMS. Earlier, more aggressive therapy in optic neuritis may be proven to reduce permanent axonal injury and progressive disability in MS.

Functional evaluation of retina and optic nerve in the rat model of chronic ocular hypertension

PURPOSE

To functionally characterize the rat retina and optic nerve after chronic elevation of the intraocular pressure (IOP) using electroretinography (ERG) and computerized pupillometry.

METHODS

Chronic elevation of the IOP was induced in Brown Norway rats by combined injection of indocyanine green dye (ICG) into the anterior chamber and diode laser treatment, followed by ERG and pupil light reflex (PLR) monitoring.

RESULTS

Laser treatment induced significant elevation of the IOP in operated eyes for 6 weeks, with maximal values observed 14 days postoperatively (ctrl=18.4+/-2.4 and operated=35+/-8.4 mmHg; mean+/-sd). Preoperative values for the PLR(ratio) were 68.5+/-4% (mean+/-sem; %). Three days postoperatively the PLR(ratio) decreased to 60.3+/-10.3%, but was not significantly different compared to preoperative values (p > 0.05 Kruskal-Wallis non-parametric test with Dunn's post-test). However, 7, 14 and 21 days postoperatively the PLR function dramatically decreased to 14.6+8.6, 11.5+/-6.7 and 12.6+/-4%, respectively, and was significantly smaller compared to preoperative values (p < 0.01). At day 28 the PLR significantly recovered and was not significantly different compared to preoperative values (PLR(ratio)=38.5+/-8.6, p > 0.05). However, 35 days after surgery the PLR started to decrease once again in the operated eyes (PLR(ratio)=17.2+/-7.4%) and was significantly smaller again compared to preoperative values (p < 0.05) The PLR values continued to decrease until the end of experiment (60 days postoperatively). ERG analysis of operated eyes revealed significantly decreased amplitudes of a- and b-waves 10d postoperatively, while oscillatory potentials (OPs) and flicker ERG (flERG) amplitudes were not detectable. However, 28 days postoperatively OPs significantly, but temporarily recovered, while a-wave, b-wave and flERG amplitudes did not significantly change compared to values observed 10d postoperatively. The ERG analysis of the operated eyes revealed significantly reduced amplitudes 60 days postoperatively. Histological analysis revealed degeneration of all retina layers and optic nerve axons.

CONCLUSIONS

Chronic ocular hypertension in rats produces dramatic damage to all retinal layers and optic nerves observed by morphological and functional methods which significantly correlate with the IOP elevation. Outer retina of glaucomatous rats seems to be more susceptible to the damage due to chronic elevation of the IOP. Chronic hypertensive rat eyes have capacity to temporarily recover function of the inner retina and optic nerve.

Optic neuritis in multiple sclerosis

PURPOSE

To review the clinical features, natural history, potential pathogenic mechanisms, differential diagnosis, and management of optic neuritis in multiple sclerosis.

METHODS

Relevant literature regarding optic neuritis in multiple sclerosis from 1970 to the present was reviewed.

RESULTS

Optic neuritis is an acute inflammatory optic neuropathy. It is the most common type of optic neuropathy causing acute visual loss in young adults (peak age at 30-40 years), especially among women. Patients usually present with an acute reduction of visual acuity, orbital pain exacerbated by eye movements, dyschromatopsia, and an afferent papillary defect, with or without swelling of the optic nerve head. Visual field testing most often reveals central defects, but others, such as centrocecal, can also occur. Magnetic resonance image (MRI) scanning of the brain should be undertaken in all cases of acute optic neuritis for diagnostic and prognostic purposes. The brain lesions of multiple sclerosis are commonly seen as T2 ovoid high-signal white matter lesions on MRI scans of the brain located in perivenular regions perpendicular to ventricles with variable enhancement. For atypical presentations of optic neuritis, additional laboratory tests, such as cerebrospinal fluid analysis, serologic tests, and visual evoked potentials, prove to be useful in the diagnosis and subsequent management of the patient. The recommended treatment for optic neuritis is intravenous steroids, as shown in the Optic Neuritis Treatment Trial (ONTT).

CONCLUSION

Optic neuritis is often the initial presentation of multiple sclerosis. Recent advances in the understanding of the immune basis for multiple sclerosis has led to earlier and more effective treatment of this disease.

Contrast-enhanced MRI in acute optic neuritis: relationship to visual performance

The location and extent of an abnormal signal on MRI of the optic nerve affected by optic neuritis are said to correlate with the severity of initial visual loss and recovery. We used gadolinium-enhanced fat-suppressed MRI to show abnormal enhancement of the optic nerve to determine the sensitivity of this modality in acute optic neuritis and whether the abnormal enhancement correlates with presenting visual deficits or recovery. A total of 107 patients, 93 with follow-up (68 steroid treated), were included; 101 patients had enhancement of the affected optic nerve and no unaffected nerve enhanced. The baseline visual performance was similar between nerves with and without enhancement. Optic nerves with enhancement in the optic canal had poorer colour vision (P = 0.04) and nerves with all segments involved had worse threshold perimetry (P = 0.001) and colour vision (P = 0.008). Nerves with enhancement >10 mm had worse threshold perimetry (P = 0.004), while nerves with enhancing segments >17 mm had poorer baseline visual acuity (P = 0.02), threshold perimetry (P = 0.009) and colour vision (P = 0.01). For all parameters of vision, recovery was similar regardless of location or length of abnormal enhancement. Abnormal contrast enhancement of the optic nerve is a sensitive (94%) finding in acute optic neuritis and is absent in unaffected or previously affected optic nerves. Although lesions involving the canal or longer segments of optic nerve have worse starting vision, the location and length of enhancement are not predictive of recovery.

Assessment of optic nerve damage in multiple sclerosis using magnetic resonance imaging

The MR imaging-based assessment of the optic nerve in optic neuritis and multiple sclerosis provides information that is complementary to clinical and electrophysiological methods. The standard and more tissue destruction specific methods can be used in strategies to measure treatment efficacy and for understanding the mechanisms of relapse, recovery, and failure of recovery.

An ophthalmic surgeon's view of orbital imaging techniques

Selection of an orbital imaging technique requires a thorough understanding of pertinent anatomy applied to relevant clinical history and detailed ophthalmic examination. The clinical finding should direct the clinician to the imaging study that provides maximum information and narrows diagnostic considerations for the individual patient. Clinical examples are provided to illustrate the rationale in ordering magnetic resonance images, computed tomography, ocular ultrasound, and color Doppler arteriography of orbital processes.