Magnetization transfer saturation reveals subclinical optic nerve injury in pediatric-onset multiple sclerosis

BACKGROUND

The presence of subclinical optic nerve (ON) injury in youth living with pediatric-onset MS has not been fully elucidated. Magnetization transfer saturation (MTsat) is an advanced magnetic resonance imaging (MRI) parameter sensitive to myelin density and microstructural integrity, which can be applied to the study of the ON.

OBJECTIVE

The objective of this study was to investigate the presence of subclinical ON abnormalities in pediatric-onset MS by means of magnetization transfer saturation and evaluate their association with other structural and functional parameters of visual pathway integrity.

METHODS

Eleven youth living with pediatric-onset MS (ylPOMS) and no previous history of optic neuritis and 18 controls underwent standardized brain MRI, optical coherence tomography (OCT), Magnetoencephalography (MEG)-Visual Evoked Potentials (VEPs), and visual battery. Data were analyzed with mixed effect models.

RESULTS

While ON volume, OCT parameters, occipital MEG-VEPs outcomes, and visual function did not differ significantly between ylPOMS and controls, ylPOMS had lower MTsat in the supratentorial normal appearing white matter (-0.26 nU, p = 0.0023), and in both in the ON (-0.62 nU, p < 0.001) and in the normal appearing white matter of the optic radiation (-0.56 nU, p = 0.00071), with these being positively correlated (+0.57 nU, p = 0.00037).

CONCLUSIONS

Subclinical microstructural injury affects the ON of ylPOMS. This may appear as MTsat changes before being detectable by other currently available testing.

Potential biological contributers to the sex difference in multiple sclerosis progression

Multiple sclerosis (MS) is an immune-mediated disease that targets the myelin sheath of central nervous system (CNS) neurons leading to axon injury, neuronal death, and neurological progression. Though women are more highly susceptible to developing MS, men that develop this disease exhibit greater cognitive impairment and accumulate disability more rapidly than women. Magnetic resonance imaging and pathology studies have revealed that the greater neurological progression seen in males correlates with chronic immune activation and increased iron accumulation at the rims of chronic white matter lesions as well as more intensive whole brain and grey matter atrophy and axon loss. Studies in humans and in animal models of MS suggest that male aged microglia do not have a higher propensity for inflammation, but may become more re-active at the rim of white matter lesions as a result of the presence of pro-inflammatory T cells, greater astrocyte activation or iron release from oligodendrocytes in the males. There is also evidence that remyelination is more efficient in aged female than aged male rodents and that male neurons are more susceptible to oxidative and nitrosative stress. Both sex chromosome complement and sex hormones contribute to these sex differences in biology.

Machine learning classification of multiple sclerosis in children using optical coherence tomography

BACKGROUND

In children, multiple sclerosis (MS) is the ultimate diagnosis in only 1/5 to 1/3 of cases after a first episode of central nervous system (CNS) demyelination. As the visual pathway is frequently affected in MS and other CNS demyelinating disorders (DDs), structural retinal imaging such as optical coherence tomography (OCT) can be used to differentiate MS.

OBJECTIVE

This study aimed to investigate the utility of machine learning (ML) based on OCT features to identify distinct structural retinal features in children with DDs.

METHODS

This study included 512 eyes from 187 (n_eyes = 374) children with demyelinating diseases and 69 (n_eyes = 138) controls. Input features of the analysis comprised of 24 auto-segmented OCT features.

RESULTS

Random Forest classifier with recursive feature elimination yielded the highest predictive values and identified DDs with 75% and MS with 80% accuracy, while multiclass distinction between MS and monophasic DD was performed with 64% accuracy. A set of eight retinal features were identified as the most important features in this classification.

CONCLUSION

This study demonstrates that ML based on OCT features can be used to support a diagnosis of MS in children.

Leveraging Visual Outcome Measures to Advance Therapy Development in Neuroimmunologic Disorders

The visual system offers unparalleled precision in the assessment of neuroaxonal damage. With the majority of patients with multiple sclerosis (MS) experiencing afferent and efferent visual dysfunction, outcome measures capturing these deficits provide insight into neuroaxonal injury, even in those with minimal disability. Ideal for use in clinical trials, visual measures are generally inexpensive, accessible, and reproducible. Quantification of visual acuity, visual fields, visual quality of life, and electrophysiologic parameters allows assessment of function, whereas optical coherence tomography (OCT) provides reliable measures of the structural integrity of the anterior afferent visual pathway. The technology of oculomotor biometrics continues to advance, and discrete measures of fixation, smooth pursuit, and saccadic eye movement abnormalities are ready for inclusion in future trials of MS progression. Visual outcomes allow tracking of neuroaxonal injury and aid in distinguishing MS from diseases such as neuromyelitis optica spectrum disorder (NMOSD) or myelin oligodendrocyte glycoprotein antibody-associated diseases (MOGAD). OCT has also provided unique insights into pathophysiology, including the identification of foveal pitting in NMOSD, possibly from damage to Müller cells, which carry an abundance of aquaporin-4 channels. For some study designs, the cost-benefit ratio favors visual outcomes over more expensive MRI outcomes. With the next frontier of therapeutics focused on remyelination and neuroprotection, visual outcomes are likely to take center stage. As an international community of collaborative, committed, vision scientists, this review by the International MS Visual System Consortium (IMSVISUAL) outlines the quality standards, informatics, and framework needed to routinely incorporate vision outcomes into MS and NMOSD trials.

Interocular Difference in Retinal Nerve Fiber Layer Thickness Predicts Optic Neuritis in Pediatric-Onset Multiple Sclerosis

BACKGROUND

Optical coherence tomography (OCT) is capable of quantifying retinal damage. Defining the extent of anterior visual pathway injury is important in multiple sclerosis (MS) as a way to document evidence of prior disease, including subclinical injury, and setting a baseline for patients early in the course of disease. Retinal nerve fiber layer (RNFL) thickness is typically classified as low if values fall outside of a predefined range for a healthy population. In adults, an interocular difference (IOD) in RNFL thickness greater than 5 μm identified a history of unilateral optic neuritis (ON). Through our PERCEPTION (PEdiatric Research Collaboration ExPloring Tests in Ocular Neuroimmunology) study, we explored whether RNFL IOD informs on remote ON in a multicenter pediatric-onset MS (POMS) cohort.

METHODS

POMS (defined using consensus criteria and first attack <18 years) patients were recruited from 4 academic centers. A clinical history of ON (>6 months prior to an OCT scan) was confirmed by medical record review. RNFL thickness was measured on Spectralis machines (Heidelberg, Germany). Using a cohort of healthy controls from our centers tested on the same machines, RNFL thickness <86 μm (<2 SDs below the mean) was defined as abnormal. Based on previously published findings in adults, an RNFL IOD >5 μm was defined as abnormal. The proportions of POMS participants with RNFL thinning (<86 μm) and abnormal IOD (>5 μm) were calculated. Logistic regression was used to determine whether IOD was associated with remote ON.

RESULTS

A total of 157 participants with POMS (mean age 15.2 years, SD 3.2; 67 [43%] with remote ON) were enrolled. RNFL thinning occurred in 45 of 90 (50%) ON eyes and 24 of 224 (11%) non-ON eyes. An IOD >5 μm was associated with a history of remote ON (P < 0.001). An IOD >5 μm occurred in 62 participants, 40 (65%) with remote ON. Among 33 participants with remote ON but normal RNFL values (≥86 μm in both eyes), 14 (42%) were confirmed to have ON by IOD criteria (>5 μm).

CONCLUSIONS

In POMS, the diagnostic yield of OCT in confirming remote ON is enhanced by considering RNFL IOD, especially for those patients with RNFL thickness for each eye in the normal range. An IOD >5 μm in patients with previous visual symptoms suggests a history of remote ON.

Multiple Sclerosis Presenting with Sixth Nerve Palsy in a Child

We report a child with multiple sclerosis who presented with sixth nerve palsy. She is a twelve-year-old Bahraini female presented to the ophthalmology department complaining of double vision. She also had imbalance and paraesthesia. Extraocular muscle examination showed restriction of abduction in the right eye. There was no change in vision. MRI showed right eye optic neuritis (ON) and demyelination which was indicative of multiple sclerosis (MS). Ocular coherence tomography (OCT) showed thinning of nerve fibres of both eyes which was consistent with subclinical optic neuritis. Neurological examination showed brisk knee jerk on the left side and incoordination of movement on the same side. Disability Status Scale (EDSS) showed a score of 3.0. She was given Solu-medrol 500 mg intravenously (IV) in addition to omeprazole 40 mg IV and Vitamin D3 (cholecalciferol) 50,000 IU cap weekly for 8 weeks and Neurorubine forte tablets (vitamin B1, 6, 12) once a day for 2 months. She became asymptomatic in her follow-up visits. Children with MS can present as sixth cranial nerve palsy. Clinicians should have a high index of suspicion for early diagnosis and treatment. In addition to MRI, OCT is a useful diagnostic tool for optic neuritis and MS especially in children.

Structural correlates of atypical visual and motor cortical oscillations in pediatric-onset multiple sclerosis

We have previously demonstrated that pediatric‐onset multiple sclerosis (POMS) negatively impacts the visual pathway as well as motor processing speed. Relationships between MS‐related diffuse structural damage of gray and white matter (WM) tissue and cortical responses to visual and motor stimuli remain poorly understood. We used magnetoencephalography in 14 POMS patients and 15 age‐ and sex‐matched healthy controls to assess visual gamma (30–80 Hz), motor gamma (60–90 Hz), and motor beta (15–30 Hz) cortical oscillatory responses to a visual‐motor task. Then, 3T MRI was used to: (a) calculate fractional anisotropy (FA) of the posterior visual and corticospinal motor WM pathways and (b) quantify volume and thickness of the cuneus and primary motor cortex. Visual gamma band power was reduced in POMS and was associated with reduced FA of the optic radiations but not with loss of cuneus volume or thickness. Activity in the primary motor cortex, as measured by postmovement beta rebound amplitude associated with peak latency, was decreased in POMS, although this reduction was not predicted by structural metrics. Our findings implicate loss of WM integrity as a contributor to reduced electrical responses in the visual cortex in POMS. Future work in larger cohorts will inform on the cognitive implications of this finding in terms of visual processing function and will determine whether the progressive loss of brain volume known to occur in POMS ultimately contributes to both progressive dysfunction in such tasks as well as progressive reduction in cortical electrical responses in the visual cortex.

Effects of Optic Neuritis, T2 Lesions, and Microstructural Diffusion Integrity in the Visual Pathway on Cortical Thickness in Pediatric-Onset Multiple Sclerosis

BACKGROUND AND PURPOSE

Pediatric-onset multiple sclerosis (POMS) is associated with focal inflammatory lesions and the loss of cortical and deep gray matter. Optic neuritis (ON) and white matter (WM) lesions in the visual pathway can directly contribute to visual cortical mantle thinning. We determine the relative contributions of MS insult on anterior and posterior visual pathway integrity.

METHODS

High- and low-contrast visual acuity, optical coherence tomography (OCT), and 3T MRI scans were obtained from 20 POMS patients (10 with remote ON) and 22 age- and sex-matched healthy controls. Cortical mantle thickness was measured using FreeSurfer. Fractional anisotropy (FA) and mean diffusivity were calculated for postchiasmal optic radiations (with and without WM lesions). Groups were compared using Student's t-test (adjusted for multiple comparisons), and simple linear regression was used to investigate interrelationships between measures.

RESULTS

Mean cortical thickness of the whole brain was reduced in patients (2.49 mm) versus controls (2.58 mm, P = .0432) and in the visual cortex (2.07 mm vs. 2.17 mm, P = .0059), although the foveal confluence was spared. Mean FA of the optic radiations was reduced in POMS (.40) versus controls (.43, P = .0042) and correlated with visual cortical mantle thickness in POMS (P = .017). Visual acuity, OCT measures, and lesion volumes in the optic radiations were not associated with cortical mantle thickness.

CONCLUSIONS

POMS negatively impacts the integrity of the anterior visual pathway, but it is the loss of WM integrity that drives anterograde loss of the cortical mantle. Preserved visual acuity and foveal sparing imply some degree of functional and structural resilience.

Newer Treatment Approaches in Pediatric-Onset Multiple Sclerosis

PURPOSE OF REVIEW

With the recognition that pediatric-onset multiple sclerosis (POMS) is characterized by more prominent disease activity, earlier age at onset of disability milestones, and more prominent cognitive impairment compared with physical disability earlier in the disease course compared with adult-onset multiple sclerosis (AOMS), there has been increasing interest in identifying optimal and safe treatment approaches to achieve better disease control in this group. Injectable therapies have been traditionally used as first line in this population, although not formally approved. This review focuses on current treatment and monitoring approaches in POMS.

RECENT FINDINGS

In the past few years, and despite the paucity of FDA-approved medications for use in POMS, an increasing trend toward using newer disease-modifying therapies (DMTs) in this group is observed. However, escalation (as opposed to induction) remains the most frequent approach, and many children continue to be untreated before age 18, particularly before age 12. The only FDA- and EMA-approved disease-modifying therapy in POMS is fingolimod; however, dimethyl fumarate, teriflunomide, natalizumab, ocrelizumab, and alemtuzumab either have been evaluated in observational studies or are being currently investigated in formal randomized controlled trials for use in POMS and appear to be safe in this group. Autologous hematopoietic stem cell transplantation has also been evaluated in a small series. Clinical outcome measures and MS biomarkers have been poorly studied in POMS; however, the use of composite functional scores, neurofilament light chain, optical coherence tomography, and imaging findings is being increasingly investigated to improve early diagnosis and efficient monitoring of POMS. Off-label use of newer DMTs in POMS is increasing, and based on retrospective data, and phase 2 trials, this approach appears to be safe in children. Results from ongoing trials will help clarify the safety and efficacy of these therapies in the future. Fingolimod is the only FDA-approved medication for use in POMS. Outcome measures and biomarkers used in AOMS are being studied in POMS and are greatly needed to quantify treatment response in this group.

Pediatric optic neuritis

PURPOSE OF REVIEW

Pediatric optic neuritis may be challenging to diagnose and treat. Significant clinical investigation of optic neuritis occurring in adults guides current clinical practices. Differences in presentation and prognosis exist for pediatric patients with optic neuritis when compared with adults including the risk of developing multiple sclerosis. The aim of this review is to provide an update on latest advances in the diagnosis, treatment and current research concerning pediatric optic neuritis.

RECENT FINDINGS

Limited case series and retrospective reviews constitute much of the data we know about patients with pediatric optic neuritis. Pediatric optic neuritis is included in the spectrum of neuroinflammatory diseases. Testing modalities (ocular coherence tomography and visual evoked potentials) and serologic testing (antibodies against aquaporin-4 and myelin oligodendrocyte glycoprotein) are being investigated for diagnostic and prognostic value. The low incidence of pediatric optic neuritis results in small sample sizes may contribute to conflicting results of different studies.

SUMMARY

Recent advances in diagnostic and serologic testing in pediatric neuritis may offer better diagnosis, treatment and prediction of prognosis. Validation requires well designed prospective research.

Radiologically isolated syndrome in children: Current knowledge and future directions

As the use of magnetic resonance imaging (MRI) grows in clinical practice, clinicians are increasingly faced with the difficult task of interpreting the significance of incidental findings on brain MRI. Among individuals found to have incidental brain MRI findings, a small number have white matter abnormalities on MRI that resemble the demyelinating lesions of multiple sclerosis (MS) in the absence of a history of relevant clinical symptoms. This has been termed radiologically isolated syndrome (RIS). Recent years have seen growing interest in RIS, with observational studies that have specifically focused on answering questions regarding the subsequent risk of future clinical events and diagnosis of MS in adults and children with these findings. Given the high rate of subsequent clinical events seen in adult studies, knowledge related to RIS in children is paramount, particularly given the higher disease activity and burden in children with MS. This review examines this question, providing an overview of RIS with a focus on its significance in children including current definitions, its association with MS, and knowledge related to therapeutic interventions for RIS. We conclude with suggestions for an approach to assessment of and subsequent surveillance in children fulfilling criteria for RIS and directions for future study.

Pediatric Optic Neuritis: What Is New

Few diseases blur the margins between their childhood and adult-onset varieties as much as optic neuritis. This report will review our state of knowledge of pediatric optic neuritis, as well as its relationship to the latest consensus definitions of neuroinflammatory disease. Current diagnostic and treatment options will be explored, as well as our potential to uncover an understanding of pediatric optic neuritis through systematic prospective studies. The risk of evolving multiple sclerosis is probably less than in adults, but pediatric optic neuritis is more likely to be an initial manifestation of acute disseminated encephalomyelitis. Steroids may hasten visual recovery, but they do not change visual outcome except in cases because of neuromyelitis optica. The role of puberty in modifying the presentation and risk associations is unknown. Prospective studies are required to resolve these diagnostic and management issues.