Markus Bock

Optic neuritis interferes with optical coherence tomography and magnetic resonance imaging correlations

Background: Retinal nerve fibre layer (RNFL) thinning is associated with brain atrophy in multiple sclerosis (MS). An influence of optic neuritis is well documented but sparsely investigated. Recently, the retinal ganglion cell layer (GCL) has been shown to provide superior information regarding visual function and retinal neurodegeneration as compared with RNFL. Objective: To investigate the association of white and grey matter brain volume with peripapillary RNFL and macular GCL in MS patients with and without a history of optic neuritis. Methods: 63 patients with relapsing–remitting MS were included in a two-centre cross-sectional prospective study. All patients underwent retinal examination with spectral domain optical coherence tomography and 1.5 T MRI for determination of normalized brain volume (NBV), white matter volume (NWMV) and grey matter volume (NGMV). Results: Both RNFL and GCL were associated with NBV, NWMV and NGMV in eyes without previous optic neuritis. This association is disrupted in the case of NGMV following optic neuritis. Conclusions: Both RNFL and GCL as parameters of neuro-axonal damage are comparably linked to whole brain as well as white and grey matter atrophy. An event of optic neuritis interferes with this relation, adding further damage to the optic nerve and disrupting especially an association with grey matter.

Patterns of retinal nerve fiber layer loss in multiple sclerosis patients with or without optic neuritis and glaucoma patients

OBJECTIVE Optical coherence tomography (OCT) has gained increasing attention in multiple sclerosis (MS) research and has been suggested as outcome measure for neuroprotective therapies. However, to date it is not clear whether patterns of retinal nerve fiber layer thickness (RNFLT) loss are different in MS compared to other diseases such as glaucoma and data on RNFLT loss in MS patients with or without optic neuritis (ON/NON) have remained inconsistent or even contradictory. METHODS In this large cross-sectional study we analyzed the patterns of axonal loss of retinal ganglion cells in MS eyes (n=262) with and without history of ON (MS/ON: 73 eyes; MS/NON: 189 eyes) and patients eyes with glaucomatous optic disc atrophy (GA: n=22; 39 eyes) in comparison to healthy control eyes (HC: n=406 eyes). RESULTS We found that significant average and quadrant RNFLT loss is detectable by OCT in both MS and GA patients compared to healthy controls (p<0.01). The age- and gender adjusted average and quadrant RNFLT did not differ significantly between MS and GA patients (p>0.05). Average (p<0.0001) and quadrant (p<0.05) RNFL thinning is significantly more severe in MS/ON versus MS/NON eyes, and the extent of RNFL thinning varies across quadrants in MS/ON eyes with the highest degree of RNFLT loss in the temporal quadrant (p<0.001). CONCLUSION RNFLT reduction across all four quadrants in MS patients as a whole as well as in MS/NON eyes argues for a diffuse neurodegenerative process. Superimposed inflammatory attacks to the optic nerve may cause additional axonal damage with a temporal preponderance. Future studies are necessary to further evaluate the capacity of OCT to depict disease specific damage patterns.

Correlation of self-assessed fatigue and alertness in multiple sclerosis

Background: Fatigue is the most common symptom in multiple sclerosis patients, but is difficult to measure; quantification thus relies on self-assessed questionnaires. Objective: To evaluate a battery of neuropsychological tests regarding their capacity to objectify self-reported fatigue. Methods: We assessed the correlation between age, gender, education, Kurtzke’s Expanded Disability Status Scale, depression, fatigue and neuropsychological testing using a cross-sectional approach in 110 multiple sclerosis patients. Fatigue was measured with the Fatigue Severity Scale. Cognition was measured using a series of neuropsychological tests including three subtests of the Test of Attentional Performance, the Brief Repeatable Battery of Neuropsychological Tests and the Faces Symbol Test. Results: According to the Fatigue Severity Scale 51.4% of the cohort were fatigued (scores ≥4). Age, education and depression showed a significant correlation with the Fatigue Severity Scale. Only 5.5% of the cohort exhibited cognitive impairment in the Brief Repeatable Battery of Neuropsychological Tests scores. After correction for age, education, Expanded Disability Status Scale and depression, Fatigue Severity Scale scores were an independent predictor of performance in the alertness subtest of the Test of Attentional Performance (standardized coefficient beta = 0.298, p = 0.014). Conclusion: The alertness subtest of the Test of Attentional Performance may offer an objective method of evaluating self-reported fatigue, and may therefore — in addition to the Fatigue Severity Scale — be a suitable tool for the assessment of multiple sclerosis patients complaining of fatigue.

Time domain and spectral domain optical coherence tomography in multiple sclerosis: a comparative cross-sectional study.

Conventional time domain optical coherence tomography has been established for the in vivo assessment of retinal axonal loss in multiple sclerosis. The innovative spectral domain imaging is superior to the conventional technique with respect to data acquisition speed, resolution and reproducibility. However, until now comparability of the two techniques has not been investigated in multiple sclerosis. In this study involving 55 multiple sclerosis patients, data obtained using both techniques (Stratus time domain optical coherence tomography and Cirrus spectral domain optical coherence tomography, Carl Zeiss Meditec) showed an excellent correlation (Pearson’s r = 0.926, p < 0.001). However, owing to considerable differences in absolute retinal nerve fibre layer measurements (mean ± standard deviation 8.1 µm ± 6.2, range -12 to 23 µm), results from the two devices are not interchangeable.

Impairment of contrast visual acuity as a functional correlate of retinal nerve fibre layer thinning and total macular volume reduction in multiple sclerosis

Objectives To analyse the association between retinal nerve fibre layer thickness (RNFLT) and total macular volume (TMV) as measured by optical coherence tomography, and contrast sensitivity (CS) measured by Functional Acuity Contrast Testing (FACT) in relapsing-remitting multiple sclerosis; and to investigate whether FACT testing by a contrast box device is feasible in multiple sclerosis (MS). Methods fact was performed using the Optec 6500 P vision testing system with best correction under photopic and mesopic conditions without glare. The Area Under the Log Contrast Sensitivity Function (AUC) was calculated. RNFLT and TMV were assessed by Stratus optical coherence tomography. All participants underwent visual acuity testing (Snellen), spherical refractive error testing and cylindrical refractive error testing. Results 85 relapsing-remitting multiple sclerosis patients (170 eyes) and 35 healthy controls (HC, 70 eyes) were measured. AUC Day and Night were lower in MS than in HC (p<0.001) when correcting for age, as were mean RNFLT and TMV (p<0.001 and p=0.018, respectively). Both RNFLT and TMV predicted contrast sensitivity in MS (AUC Day: standardised coefficient β=0.277, p<0.001, and β=0.262, p<0.001, respectively; AUC Night: β=0.202, p=0.009 and β=0.222, p=0.004, respectively, linear regressions). In HC, there was no correlation between RNFLT or TMV and contrast sensitivity. Conclusion (1) Contrast sensitivity is reduced in MS versus HC; (2) RNFL and TMV as morphological measures of retinal axonal loss are predictors of contrast sensitivity as a functional visual parameter in MS but not in HC; and (3) FACT with the contrast box is a novel, feasible and rapid method to assess contrast sensitivity in MS.

A Diet Mimicking Fasting Promotes Regeneration and Reduces Autoimmunity and Multiple Sclerosis Symptoms

Dietary interventions have not been effective in the treatment of multiple sclerosis (MS). Here, we show that periodic 3-day cycles of a fasting mimicking diet (FMD) are effective in ameliorating demyelination and symptoms in a murine experimental autoimmune encephalomyelitis (EAE) model. The FMD reduced clinical severity in all mice and completely reversed symptoms in 20% of animals. These improvements were associated with increased corticosterone levels and regulatory T (Treg) cell numbers and reduced levels of pro-inflammatory cytokines, TH1 and TH17 cells, and antigen-presenting cells (APCs). Moreover, the FMD promoted oligodendrocyte precursor cell regeneration and remyelination in axons in both EAE and cuprizone MS models, supporting its effects on both suppression of autoimmunity and remyelination. We also report preliminary data suggesting that an FMD or a chronic ketogenic diet are safe, feasible, and potentially effective in the treatment of relapsing-remitting multiple sclerosis (RRMS) patients (NCT01538355).

Attention Network Test reveals alerting network dysfunction in multiple sclerosis

Attention is one of the cognitive domains typically affected in multiple sclerosis. The Attention Network Test was developed to measure the function of the three distinct attentional networks, alerting, orienting, and executive control. The Attention Network Test has been performed in various neuropsychiatric conditions, but not in multiple sclerosis. Our objective was to investigate functions of attentional networks in multiple sclerosis by means of the Attention Network Test. Patients with relapsing—remitting multiple sclerosis (n = 57) and healthy controls (n = 57) matched for age, sex, and education performed the Attention Network Test. Significant differences between patients and controls were detected in the alerting network (p = 0.003), in contrast to the orienting (p = 0.696) and the conflict (p = 0.114) network of visual attention. Mean reaction time in the Attention Network Test was significantly longer in multiple sclerosis patients than in controls (p = 0.032), Multiple sclerosis patients benefited less from alerting cues for conflict resolution compared with healthy controls. The Attention Network Test revealed specific alterations of the attention network in multiple sclerosis patients which were not explained by an overall cognitive slowing.

Encephalopathy, visual disturbance and hearing loss—recognizing the symptoms of Susac syndrome

Background. A 23 year-old female presented to a neurology department with a 3 year history of recurrent episodes involving hearing loss, encephalopathy, focal neurological deficits, and visual field deficits. In the 3 years before presentation, the patient had been treated with methylprednisolone for suspected acute demyelinating encephalomyelitis and peripheral otogenic dysfunction from which she made a complete recovery, and for a visual defect in both eyes caused by bilateral branch retinal arterial occlusion, from which she partially improved and commenced long-term treatment with acetylsalicylic acid.Investigations. Detailed history, clinical examination, extensive laboratory work-up, cerebrospinal fluid analysis, cerebral and spinal MRI, periventricular single-voxel 1H magnetic resonance spectroscopy, retinal fluorescence angiography, optical coherence tomography, audiometry, neurophysiological work-up (EEG, evoked potentials).Diagnosis. Susac syndrome, characterized by a combination of encephalopathy, branch retinal artery occlusions, and hearing loss.Management. Long-term immunosuppressive treatment with azathioprine (150 mg/day) and prednisolone (10 mg/day), and inhibition of thrombocyte function with acetylsalicylic acid (100 mg/day).

Is Metabolic Flexibility Altered in Multiple Sclerosis Patients

Objectives Metabolic flexibility is defined as ability to adjust fuel oxidation to fuel availability. Multiple sclerosis (MS) results in reduced muscle strength and exercise intolerance. We tested the hypothesis that altered metabolic flexibility contributes to exercise intolerance in MS patients. Methods We studied 16 patients (all on glatiramer) and 16 matched healthy controls. Energy expenditure (EE), and carbohydrate (COX) and lipid oxidation (LOX) rates were determined by calorimetry, before and after an oral glucose load. We made measurements either at rest (canopy device) or during 40 min low-grade (0.5 W/kg) exercise (metabolic chamber). We also obtained plasma, and adipose tissue and skeletal muscle dialysate samples by microdialysis to study tissue-level metabolism under resting conditions. Results At rest, fasting and postprandial plasma glucose, insulin, and free fatty acid levels did not differ between patients and controls. Fasting and postprandial COX was higher and LOX lower in patients. In adipose, fasting and postprandial dialysate glucose, lactate, and glycerol levels were higher in patients vs. controls. In muscle, fasting and postprandial dialysate metabolite levels did not differ significantly between the groups. During exercise, EE did not differ between the groups. However, COX increased sharply over 20 min in patients, without reaching a steady state, followed by an immediate decrease within the next 20 min and fell even below basal levels after exercise in patients, compared to controls. Conclusions Glucose tolerance is not impaired in MS patients. At rest, there is no indication for metabolic inflexibility or mitochondrial dysfunction in skeletal muscle. The increased adipose tissue lipolytic activity might result from glatiramer treatment. Autonomic dysfunction might cause dysregulation of postprandial thermogenesis at rest and lipid mobilization during exercise.

Tracking CNS and systemic sources of oxidative stress during the course of chronic neuroinflammation

The functional dynamics and cellular sources of oxidative stress are central to understanding MS pathogenesis but remain elusive, due to the lack of appropriate detection methods. Here we employ NAD(P)H fluorescence lifetime imaging to detect functional NADPH oxidases (NOX enzymes) in vivo to identify inflammatory monocytes, activated microglia, and astrocytes expressing NOX1 as major cellular sources of oxidative stress in the central nervous system of mice affected by experimental autoimmune encephalomyelitis (EAE). This directly affects neuronal function in vivo, indicated by sustained elevated neuronal calcium. The systemic involvement of oxidative stress is mirrored by overactivation of NOX enzymes in peripheral CD11b+ cells in later phases of both MS and EAE. This effect is antagonized by systemic intake of the NOX inhibitor and anti-oxidant epigallocatechin-3-gallate. Together, this persistent hyper-activation of oxidative enzymes suggests an “oxidative stress memory” both in the periphery and CNS compartments, in chronic neuroinflammation.