Mechanical ventilation and tracheostomy in multiple sclerosis

CNS Demyelinating Attacks Requiring Ventilatory Support With Myelin Oligodendrocyte Glycoprotein or Aquaporin-4 Antibodies

Background and Objective

Severe attacks of myelin oligodendrocyte glycoprotein (MOG) antibody–associated disorder (MOGAD) and aquaporin-4 (AQP4) antibody–positive neuromyelitis optica spectrum disorder (AQP4-NMOSD) may require ventilatory support, but data on episodes are limited, particularly for MOGAD. We sought to compare the frequency, characteristics, and outcomes of MOGAD and AQP4-NMOSD attacks requiring ventilatory support.

Methods

This retrospective descriptive study identified Mayo Clinic patients (January 1, 1996–December 1, 2020) with MOGAD or AQP4-NMOSD and an attack requiring noninvasive or invasive ventilation at Mayo Clinic or an outside facility by searching for relevant terms in their electronic medical record. Inclusion criteria were (1) attack-related requirement for noninvasive (bilevel positive airway pressure or continuous positive airway pressure) or invasive respiratory support (mechanical ventilation); (2) MOG or AQP4 antibody positivity with fulfillment of MOGAD and AQP4-NMOSD clinical diagnostic criteria, respectively; and (3) sufficient clinical details. We collected data on demographics, comorbid conditions, indication for and duration of respiratory support, MRI findings, treatments, and outcomes. The races of those with attacks requiring respiratory support were compared to those without such attacks in MOGAD and AQP4-NMOSD.

Results

Attacks requiring ventilatory support were similarly rare in patients with MOGAD (8 of 279, 2.9%) and AQP4-NMOSD (11 of 503 [2.2%]) (p = 0.63). The age at attack (median years [range]) (MOGAD 31.5 [5–47] vs AQP4-NMOSD 43 [14–65]; p = 0.01) and percentage of female sex (MOGAD 3 of 8 [38%] vs AQP4-NMOSD 10 of 11 [91%]; p = 0.04) differed. The reasons for ventilation differed between MOGAD (inability to protect airway from seizure, encephalitis or encephalomyelitis with attacks of acute disseminated encephalomyelitis 5 [62.5%] or unilateral cortical encephalitis 3 [37.5%]) and AQP4-NMOSD (inability to protect airway from cervical myelitis 9 [82%], rhombencephalitis 1 [9%], or combinations of both 1 [9%]). Median ventilation duration for MOGAD was 2 days (range 1–7 days) vs 19 days (range 6–330 days) for AQP4-NMOSD (p = 0.01). All patients with MOGAD recovered, but 2 of 11 (18%) patients with AQP4-NMOSD died of the attack. For AQP4-NMOSD, Black race was overrepresented for attacks requiring ventilatory support vs those without these episodes (5 of 11 [45%] vs 88 of 457 [19%]; p = 0.045).

Discussion

Ventilatory support is rarely required for MOGAD and AQP4-NMOSD attacks, and the indications differ. Compared to MOGAD, these attacks in AQP4-NMOSD may have higher morbidity and mortality, and those of Black race were more predisposed, which we suspect may relate to socially mediated health inequality.

Autoimmune Neurologic Emergencies

Over the past decade, understanding of autoimmune neurologic disorders has exponentially increased. Many patients present as a neurologic emergency and require timely evaluation with rapid management and intensive care. However, the diagnosis is often either missed or delayed, which may lead to a significant burden of disabling morbidity and even mortality. A high level of suspicion in the at-risk population should be maintained to facilitate more rapid diagnosis and prompt treatment. At present, there is no all-encompassing algorithm specifically applicable to the management of fulminant autoimmune neurologic disorders. This article discusses manifestations and management of various autoimmune neurologic emergencies.

Respiratory rehabilitation in multiple sclerosis: A narrative review of rehabilitation techniques

BACKGROUND

Respiratory disorders in multiple sclerosis (MS) are an important issue. They can occur early during the course of the disease, are associated with the neurological impairment, and can lead to pneumonia and respiratory failure, which are the main causes of death in advanced MS. Prevailing impaired expiratory muscles and cough abilities has been demonstrated in this population and might constitute a specific target for rehabilitation interventions. However, international guidelines lack recommendations regarding respiratory rehabilitation in MS. Here we performed a systematic review of the published literature related to respiratory rehabilitation in MS.

METHODS

We searched the databases MEDLINE via PubMed, PEDro and Cochrane Library for English or French reports of clinical trials and well-designed cohorts published up to December 2016 with no restriction on start date by using the search terms "multiple sclerosis", "respiratory rehabilitation", "respiratory muscle training", "lung volume recruitment", "cough assistance", and "mechanical in-exsufflation". Literature reviews, case reports and physiological studies were excluded. The Maastricht criteria were used to assess the quality of clinical trials. We followed the Oxford Centre for Evidence-Based Medicine guidelines to determine level of evidence and grade of recommendations.

RESULTS

Among the 21 reports of studies initially selected, 11 were retained for review. Seven studies were randomized controlled trials (RCTs), 2 were non-RCTs, and 2 were observational studies. Respiratory muscle training (inspiratory and/or expiratory) by use of a portable resistive mouthpiece was the most frequently evaluated technique, with 2 level-1 RCTs. Another level-1 RCT evaluated deep-breathing exercises. All reviewed studies evaluated home-based rehabilitation programs and focused on spirometric outcomes. The disparities in outcome measures among published studies did not allow for a meta-analysis and cough assistance devices were not evaluated in this population.

CONCLUSION

Although respiratory muscle training can improve maximal respiratory pressure in MS and lung volume recruitment can slow the decline in vital capacity, evidence is lacking to recommend specific respiratory rehabilitation programs adapted to the level of disability induced by the disease.

Respiratory dysfunction in multiple sclerosis

Respiratory dysfunction frequently occurs in patients with advanced multiple sclerosis (MS), and may manifest as acute or chronic respiratory failure, disordered control of breathing, respiratory muscle weakness, sleep disordered breathing, or neurogenic pulmonary edema. The underlying pathophysiology is related to demyelinating plaques involving the brain stem or spinal cord. Respiratory complications such as aspiration, lung infections and respiratory failure are typically seen in patients with long-standing MS. Acute respiratory failure is uncommon and due to newly appearing demyelinating plaques extensively involving areas of the brain stem or spinal cord. Early recognition of MS patients at risk for respiratory complications allows for the timely implementation of care and measures to decrease disease associated morbidity and mortality.

Overlapping CNS inflammatory diseases: differentiating features of NMO and MS

Neuromyelitis optica (NMO) has long been considered as a variant of multiple sclerosis (MS) rather than a distinct disease. This concept changed with the discovery of serum antibodies (Ab) against aquaporin-4 (AQP4), which unequivocally differentiate NMO from MS. Patients who test positive for AQP4-Abs and present with optic neuritis (ON) and transverse myelitis (TM) are diagnosed with NMO and those who show an incomplete phenotype with isolated ON or longitudinally extensive TM (LETM) or less commonly brain/brainstem disease are referred to as NMO spectrum disorders (NMOSD). However, many patients, who have overlapping features of both NMO and MS, test negative for AQP4-Abs and may be difficult to definitively diagnose. This raises important practical issues, since NMO and MS respond differently to immunomodulatory treatment and have different prognoses. Here we review distinct features of AQP4-positive NMO and MS, which might then be useful in the diagnosis of antibody-negative overlap syndromes. We identify discriminators, which are related to demographic data (non-white origin, very late onset), clinical features (limited recovery from ON, bilateral ON, intractable nausea, progressive course of disability), laboratory results (cerebrospinal fluid (CSF) pleocytosis with eosinophils and/or neutrophils, oligoclonal bands, glial fibrillary acidic protein in the CSF) and imaging (LETM, LETM with T1 hypointensity, periependymal brainstem lesions, perivenous white matter lesions, Dawson's fingers, curved or S-shaped U-fibre juxtacortical lesions). We review the value of these discriminators and discuss the compelling need for new diagnostic markers in these two autoimmune demyelinating diseases of the central nervous system.

Aquaporin-4 autoimmunity masquerading as a brainstem tumor

Brainstem glioma is a highly devastating disease, and any mass-like lesion in the brainstem can raise suspicion of this diagnosis. However, other inflammatory, demyelinating, or degenerative diseases can mimic brainstem glioma in clinical presentation and imaging features. Therefore, diagnosis based solely on imaging is often insufficient for brainstem lesions and may lead to incorrect diagnosis and treatment. This case report is the first description of central nervous system aquaporin-4 (AQP4) autoimmunity confined mainly to the brainstem. It demonstrates the wide spectrum of neuroinflammatory diseases in children and highlights the utility of surgical biopsy for suspicious brainstem lesions with atypical imaging features for glioma.

Intensive care unit admission in multiple sclerosis: increased incidence and increased mortality

OBJECTIVE

To compare the incidence of, and mortality after, intensive care unit (ICU) admission as well as the characteristics of critical illness in the multiple sclerosis (MS) population vs the general population.

METHODS

We used population-based administrative data from the Canadian province of Manitoba for the period 1984 to 2010 and clinical data from 93% of admissions to provincial high-intensity adult ICUs. We identified 5,035 prevalent cases of MS and a cohort from the general population matched 5:1 on age, sex, and region of residence. We compared these populations using incidence rates and multivariable regression models adjusting for age, sex, comorbidity, and socioeconomic status.

RESULTS

From January 2000 to October 2009, the age- and sex-standardized annual incidence of ICU admission among prevalent cohorts was 0.51% to 1.07% in the MS population and 0.34% to 0.51% in matched controls. The adjusted risk of ICU admission was higher for the MS population (hazard ratio 1.45; 95% confidence interval [CI] 1.19-1.75) than for matched controls. The MS population was more likely to be admitted for infection than the matched controls (odds ratio 1.82; 95% CI 1.10-1.32). Compared with the matched controls admitted to ICUs, 1-year mortality was higher in the MS population (relative risk 2.06; 95% CI 1.32-3.07) and was particularly elevated in patients with MS who were younger than 40 years (relative risk 3.77; 95% CI 1.45-8.11). Causes of death were MS (9.3%), infections (37.0%), and other causes (52.9%).

CONCLUSIONS

Compared with the general population, the risk of ICU admission is higher in MS, and 1-year mortality after admission is higher. Greater attention to preventing infection and managing comorbidity is needed in the MS population.

Neuromyelitis optica (Devic's syndrome)

Neuromyelitis optica (NMO) is an inflammatory demyelinating disease of the central nervous system that selectively targets the optic nerve and spinal cord, although it may also target certain areas of the brain. The majority of cases are associated with relapses. A specific biomarker, an autoantibody that targets aquaporin-4, is present in the majority of patients and facilitates the diagnosis. Detection of this biomarker in serum has enabled recognition of an expanded spectrum of clinical disorders that previously would not have met diagnostic criteria for NMO. Aquaporin-4 IgG1 autoantibodies are pathogenic and produce lesions of the brain when injected intracerebrally or systemically. The clinical course of NMO is dominated by acute attacks. Progressive worsening of disability, as occurs in prototypic multiple sclerosis, is distinctly unusual. Corticosteroids and plasma exchange are useful for management of acute attacks. Several treatments used to prevent attacks of multiple sclerosis are ineffective in this condition; effective immunotherapies include azathioprine, mycophenolate mofetil and rituximab.

Acute and chronic respiratory failure

Respiratory failure (RF) can be attributed to a plethora of neuromuscular diseases (NMDs) and manifests clinically in a multitude of overt or more subtle ways. The basic principles of pathophysiology, diagnosis and treatment of neurologic diseases and of RF apply concomitantly to this subset of patients. Various entities should be approached according to the latest evidence-based recommendations. Treatment follows the natural disease progression, from minimal respiratory assistance to mechanical ventilation (MV). A comprehensive treatment plan has to be formulated that takes into consideration the patient's wishes.

Cervical spinal demyelination with ethidium bromide impairs respiratory (phrenic) activity and forelimb motor behavior in rats

Although respiratory complications are a major cause of morbidity/mortality in many neural injuries or diseases, little is known concerning mechanisms whereby deficient myelin impairs breathing, or how patients compensate for such changes. Here, we tested the hypothesis that respiratory and forelimb motor functions are impaired in a rat model of focal dorsolateral spinal demyelination (ethidium bromide, EB). Ventilation, phrenic nerve activity and horizontal ladder walking were performed 7-14 days post-C2 injection of EB or vehicle (SHAM). EB caused dorsolateral demyelination at C2-C3 followed by significant spontaneous remyelination at 14 days post-EB. Although ventilation did not differ between groups, ipsilateral integrated phrenic nerve burst amplitude was significantly reduced versus SHAM during chemoreceptor activation at 7 days post-EB but recovered by 14 days. The ratio of ipsi- to contralateral phrenic nerve amplitude correlated with cross-sectional lesion area. This ratio was significantly reduced 7 days post-EB versus SHAM during baseline conditions, and versus SHAM and 14-day groups during chemoreceptor activation. Limb function ipsilateral to EB was impaired 7 days post-EB and partially recovered by 14 days post-EB. EB provides a reversible model of focal, spinal demyelination, and may be a useful model to study mechanisms of functional impairment and recovery via motor plasticity, or the efficacy of new therapeutic interventions to reduce severity or duration of disease.

Diaphragmatic pacing to facilitate ventilator weaning in neuromyelitis optica-associated respiratory failure

Patients with neuromyelitis optica may develop neurogenic respiratory failure in the context of severe upper cervical myelitis, which can require prolonged or indefinite mechanical ventilation. Diaphragmatic pacing has FDA approval under a humanitarian device exemption (HDE) to facilitate weaning from mechanical ventilation in the context of cervical spinal cord injury. We describe the use of diaphragmatic pacing in a patient with acute respiratory failure due to a severe attack of neuromyelitis optica on the cervical spinal cord. The device resulted in successful early ventilator weaning.

Immune mediated diseases and immune modulation in the neurocritical care unit

This chapter will review the spectrum of immune-mediated diseases that affect the nervous system and may result in an admission to the neurological intensive care unit. Immunomodulatory strategies to treat acute exacerbations of neurological diseases caused by aberrant immune responses are discussed, but strategies for long-term immunosuppression are not presented. The recommendations for therapeutic intervention are based on a synthesis of the literature, and include recommendations by the Cochrane Collaborative, the American Academy of Neurology, and other key organizations. References from recent publications are provided for the disorders and therapies in which randomized clinical trials and large evidenced-based reviews do not exist. The chapter concludes with a brief review of the mechanisms of action, dosing, and side effects of commonly used immunosuppressive strategies in the neurocritical care unit.

Neuromyelitis optica: a distinct demyelinating disease of the central nervous system

OBJECTIVES

We review and discuss the pathogenesis, epidemiology, diagnosis as well as recent advances in the treatment of NMO. We also highlight areas of future research.

METHODS

A review was carried out on reports drawn from MEDLINE until 2007.

RESULTS

Neuromyelitis optica (NMO) is a relative uncommon demyelinating disease of the central nervous system (CNS) that preferentially affects the optic nerves and spinal cord. NMO follows an unpredictable course, being either monophasic or relapsing. The relapsing form of NMO primarily affects women with onset varying from childhood to adults in their 40s or elderly. Until recently, NMO was considered to be a variant of multiple sclerosis. However, in contrast to multiple sclerosis, NMO attacks are not mediated by T cells but rather by B cells and NMO-immunoglobulin G antibodies that target aquaporin-4. Humoral immune mechanisms, including complement activation plays an important role in the pathogenesis of NMO. At present, parenteral corticosteroids are widely employed as first-line treatment of optic neuritis and myelitis attacks, whereas therapeutic plasmapheresis is applied in the case of corticosteroids failure. Various strategies for the prevention of NMO relapses have been employed in small case series with modest activity.

CONCLUSION

Recent advances in the clinical, neuroimaging, laboratory and pathological hallmarks have established that NMO is a distinct demyelinating disease of the CNS.

Palliative care in amyotrophic lateral sclerosis, Parkinson's disease, and multiple sclerosis

BACKGROUND

Amyotrophic lateral sclerosis, Parkinson's disease, atypical parkinsonian syndromes, and multiple sclerosis are progressive neurologic disorders that cumulatively afflict a large number of people. Effective end-of-life palliative care depends upon an understanding of the clinical aspects of each of these disorders.

OBJECTIVES

The authors review the unique and overlapping aspects of each of these disorders with an emphasis upon the clinical management of symptoms.

DESIGN

The authors review current management and the supporting literature.

CONCLUSIONS

Clinicians have many effective therapeutic options to choose from when managing the symptoms produced by these disorders.

The spectrum of neuromyelitis optica

Neuromyelitis optica (also known as Devic's disease) is an idiopathic, severe, demyelinating disease of the central nervous system that preferentially affects the optic nerve and spinal cord. Neuromyelitis optica has a worldwide distribution, poor prognosis, and has long been thought of as a variant of multiple sclerosis; however, clinical, laboratory, immunological, and pathological characteristics that distinguish it from multiple sclerosis are now recognised. The presence of a highly specific serum autoantibody marker (NMO-IgG) further differentiates neuromyelitis optica from multiple sclerosis and has helped to define a neuromyelitis optica spectrum of disorders. NMO-IgG reacts with the water channel aquaporin 4. Data suggest that autoantibodies to aquaporin 4 derived from peripheral B cells cause the activation of complement, inflammatory demyelination, and necrosis that is seen in neuromyelitis optica. The knowledge gained from further assessment of the exact role of NMO-IgG in the pathogenesis of neuromyelitis optica will provide a foundation for rational therapeutic trials for this rapidly disabling disease.

Diagnosis and Treatment of Neuromyelitis Optica

BACKGROUND

Neuromyelitis optica (NMO) is an uncommon CNS demyelinating syndrome often mistaken for severe multiple sclerosis (MS). Several clinical, laboratory, and neuroimaging characteristics may accurately distinguish NMO from MS early in the disease course.

REVIEW SUMMARY

NMO is usually a relapsing disorder associated with early, severe, attack-related residual disability. It is associated with a highly specific antibody marker, NMO-IgG, which targets the water channel aquaporin-4. Revised NMO diagnostic criteria require optic neuritis, acute myelitis, and 2 of the following 3 characteristics: disease-onset brain magnetic resonance imaging (MRI) that is nondiagnostic for MS, contiguous spinal cord MRI lesion extending over 3 or more vertebral segments, and NMO-IgG seropositive status. Symptoms referable to central nervous system regions other than the optic nerve and spinal cord do not necessarily exclude the diagnosis of NMO, nor does the presence of brain MRI lesions. NMO-IgG has facilitated an appreciation that the spectrum of NMO is wider than previously recognized, and includes a proportion of patients with each of recurrent longitudinally extensive myelitis, recurrent isolated optic neuritis, and Japanese opticospinal MS. In contrast to typical MS, clinical experience and case series suggest that NMO requires long-term immunosuppressive therapy.

CONCLUSIONS

NMO can be reliably differentiated from MS at an early stage using validated diagnostic criteria. The spectrum of NMO is wider than previously appreciated. Accurate, early diagnosis is critical to facilitate initiation of immunosuppressive therapy for attack prevention.