[Pathophysiology and treatment of fatigue in multiple sclerosis]

Multiple Sclerosis and SARS-CoV-2: Has the Interplay Started?

Current knowledge on Multiple Sclerosis (MS) etiopathogenesis encompasses complex interactions between the host's genetic background and several environmental factors that result in dysimmunity against the central nervous system. An old-aged association exists between MS and viral infections, capable of triggering and sustaining neuroinflammation through direct and indirect mechanisms. The novel Coronavirus, SARS-CoV-2, has a remarkable, and still not fully understood, impact on the immune system: the occurrence and severity of both acute COVID-19 and post-infectious chronic illness (long COVID-19) largely depends on the host's response to the infection, that echoes several aspects of MS pathobiology. Furthermore, other MS-associated viruses, such as the Epstein-Barr Virus (EBV) and Human Endogenous Retroviruses (HERVs), may enhance a mechanistic interplay with the novel Coronavirus, with the potential to interfere in MS natural history. Studies on COVID-19 in people with MS have helped clinicians in adjusting therapeutic strategies during the pandemic; similar efforts are being made for SARS-CoV-2 vaccination campaigns. In this Review, we look over 18 months of SARS-CoV-2 pandemic from the perspective of MS: we dissect neuroinflammatory and demyelinating mechanisms associated with COVID-19, summarize pathophysiological crossroads between MS and SARS-CoV-2 infection, and discuss present evidence on COVID-19 and its vaccination in people with MS.

Neutralizing antibodies and fatigue as predictors of low response to interferon-beta treatment in patients with multiple sclerosis

Background

The clinical impact of neutralizing antibodies against interferon-beta (NAb) is controversial. Their presence can lead to a decrease in interferon-beta (IFNβ) efficacy. Fatigue reported in patients with multiple sclerosis (MS) may be associated with an unfavorable clinical course. We conducted a prospective multicentre study to assess the association between response to IFNβ, NAb and fatigue.

Methods

Patients with relapsing-remitting MS on IFNβ treatment were included. During the second year of treatment, the patients were analyzed for NAb status and non-response criteria to IFNβ (number of relapses ≥1 during the follow-up period, increase in the Expanded Disability Status Scale ≥0.5). The score on the Modified Fatigue Impact Scale (MFIS pathological if score ≥35) was noted for each patient.

Results

Of the 176 patients included: 22.3% were NAb positive, 54.5% presented non-response criteria to IFNβ, and 57.4% had a pathological MFIS score. Fatigue was increased in NAb + patients (p = 0.0014) and they were more likely to present non-response criteria to IFNβ (p = 0.041) than NAb- patients. Multivariate logistic regression analysis showed that the presence of NAb was related to fatigue (p = 0.0032) and denoted disease activity in these patients (p = 0.026).

Conclusions

This study demonstrates the impact of NAb on the non-clinical response to IFNβ. Fatigue assessment is an indicator of IFNβ responsiveness and a predictive biomarker of deterioration on patient’s neurological status.

Myalgic encephalomyelitis/chronic fatigue syndrome and encephalomyelitis disseminata/multiple sclerosis show remarkable levels of similarity in phenomenology and neuroimmune characteristics

BACKGROUND

'Encephalomyelitis disseminata' (multiple sclerosis) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are both classified as diseases of the central nervous system by the World Health Organization. This review aims to compare the phenomenological and neuroimmune characteristics of MS with those of ME/CFS.

DISCUSSION

There are remarkable phenomenological and neuroimmune overlaps between both disorders. Patients with ME/CFS and MS both experience severe levels of disabling fatigue and a worsening of symptoms following exercise and resort to energy conservation strategies in an attempt to meet the energy demands of day-to-day living. Debilitating autonomic symptoms, diminished cardiac responses to exercise, orthostatic intolerance and postural hypotension are experienced by patients with both illnesses. Both disorders show a relapsing-remitting or progressive course, while infections and psychosocial stress play a large part in worsening of fatigue symptoms. Activated immunoinflammatory, oxidative and nitrosative (O+NS) pathways and autoimmunity occur in both illnesses. The consequences of O+NS damage to self-epitopes is evidenced by the almost bewildering and almost identical array of autoantibodies formed against damaged epitopes seen in both illnesses. Mitochondrial dysfunctions, including lowered levels of ATP, decreased phosphocreatine synthesis and impaired oxidative phosphorylation, are heavily involved in the pathophysiology of both MS and ME/CFS. The findings produced by neuroimaging techniques are quite similar in both illnesses and show decreased cerebral blood flow, atrophy, gray matter reduction, white matter hyperintensities, increased cerebral lactate and choline signaling and lowered acetyl-aspartate levels.

SUMMARY

This review shows that there are neuroimmune similarities between MS and ME/CFS. This further substantiates the view that ME/CFS is a neuroimmune illness and that patients with MS are immunologically primed to develop symptoms of ME/CFS.

Bilateral reversible corneal edema associated with amantadine use

PURPOSE

In this article, we report a case of bilateral severe reversible corneal edema caused by amantadine therapy.

CASE

A 39-year-old women was referred to us for evaluation of bilateral corneal edema. Her past medical history was significant for multiple sclerosis, anorexia, and seizures. She developed painless progressive bilateral loss of vision for the past 6 months. She was evaluated by several ophthalmologists elsewhere who felt that the patient's visual loss was secondary to a nutritional deficiency as opposed to related to multiple sclerosis. She was started on vitamin B-12 medication without improvement in her symptoms. She was then evaluated by neuro-ophthalmology. The examination revealed severe bilateral corneal edema and was referred to our corneal service for further evaluation of her corneal condition. Our examination revealed best corrected visual acuity of 20/400 bilaterally. Corneal thickness was 940 microm in the right eye and 802 microm in the left. Color vision was intact. Conjunctivas were white bilaterally. Cornea evaluation revealed diffuse stromal edema and Descemet's folds and microcystic subepithelial edema with to guttae noted. Anterior chambers were deep and quiet. A specular microscopy revealed significant pleomorphism and polymegathism with an endothelial cell count of 1,504 cells in the right eye and 1,596 in the left eye.

RESULTS

Review of the patient's medical information revealed therapy with amantadine 2 months prior to the appearance of the patient's symptoms as a means to control the patient's tremors. The patient experienced rapid resolution of the corneal edema within the next 2 months after discontinuation of the agent with recovery of best corrected visual acuity of 20/40 in the right eye and 20/30 in the left.

CONCLUSIONS

In cases of unexplained corneal edema and in the absence of any identifiable ocular cause, a review of toxic effects of systemic medications should be performed. Early diagnosis may prevent irreversible endothelial damage. Amantadine can cause endothelial failure and needs to be considered as part of the differential diagnosis of corneal edema.