Risk of cancer in patients with dermatomyositis or polymyositis. A population-based study

BACKGROUND

An association between polymyositis and cancer was first proposed in 1916, but the existence of the association has been disputed. An association between dermatomyositis and cancer is better accepted, but its magnitude is not known.

METHODS

We undertook a study to provide accurate estimates of the risk of cancer in patients with dermatomyositis or polymyositis. We studied the incidence of cancer and the rate of mortality from cancer in a population-based cohort of 788 patients with dermatomyositis or polymyositis in Sweden from 1963 through 1983. The results were compared with those for the general population.

RESULTS

Among the 396 patients with polymyositis, 42 cancers were diagnosed at the same time or after polymyositis was diagnosed in 37 patients (9 percent). The relative risk of cancer was 1.8 (95 percent confidence interval, 1.1 to 2.7) in the male patients and 1.7 (95 percent confidence interval, 1.0 to 2.5) in the female patients. Eighty-four males and 85 females died, and in 24 of these cases (14 percent) cancer was the principal cause of death. The mortality ratio (the rate of mortality from cancer in these patients as compared with that in the general population) was 0.90 (95 percent confidence interval, 0.6 to 1.4). Among the 392 patients with dermatomyositis, 61 cancers were diagnosed at the same time or after dermatomyositis was diagnosed in 59 patients (15 percent). The relative risk of cancer was 2.4 (95 percent confidence interval, 1.6 to 3.6) in the male patients and 3.4 (95 percent confidence interval, 2.4 to 4.7) in the female patients. Fifty-seven males and 110 females died, and in 67 of these cases (40 percent) cancer was the principal cause of death (mortality ratio, 3.8; 95 percent confidence interval, 2.9 to 4.8).

CONCLUSIONS

The risk of cancer is increased in patients with polymyositis or dermatomyositis. In patients with dermatomyositis there is also a higher rate of mortality from cancer.

Skeletal muscle inflammation and insulin resistance in obesity

Obesity is associated with chronic inflammation, which contributes to insulin resistance and type 2 diabetes mellitus. Under normal conditions, skeletal muscle is responsible for the majority of insulin-stimulated whole-body glucose disposal; thus, dysregulation of skeletal muscle metabolism can strongly influence whole-body glucose homeostasis and insulin sensitivity. Increasing evidence suggests that inflammation occurs in skeletal muscle in obesity and is mainly manifested by increased immune cell infiltration and proinflammatory activation in intermyocellular and perimuscular adipose tissue. By secreting proinflammatory molecules, immune cells may induce myocyte inflammation, adversely regulate myocyte metabolism, and contribute to insulin resistance via paracrine effects. Increased influx of fatty acids and inflammatory molecules from other tissues, particularly visceral adipose tissue, can also induce muscle inflammation and negatively regulate myocyte metabolism, leading to insulin resistance.

Incidence of malignant disease in biopsy-proven inflammatory myopathy. A population-based cohort study

BACKGROUND

The validity and magnitude of an association between myositis and malignant disease continue to be debated. Such issues as the legitimacy of a myositis diagnosis and distinction among myositis subgroups in previous population-based studies remain unresolved.

OBJECTIVE

To determine the risk for malignant disease in patients with biopsy-proven inflammatory myopathies.

DESIGN

Population-based, retrospective cohort study.

SETTING

Victoria, Australia.

PATIENTS

537 patients in whom a biopsy-positive idiopathic inflammatory myopathy was first diagnosed from 1981 through 1995.

MEASUREMENTS

Standardized incidence ratios were calculated to compare the incidence of malignant disease in patients with inflammatory myopathy and the general population.

RESULTS

A total of 116 cases of malignant disease were found in 104 patients. Seventy-four cases were identified concurrently with (within 7 days) or after diagnosis of myositis. The highest risk for malignant disease was associated with dermatomyositis (standardized incidence ratio, 6.2 [95% CI, 3.9 to 10.0]). The risk was also increased in polymyositis (standardized incidence ratio, 2.0 [CI, 1.4 to 2.7]), although the relative risk for malignant disease in dermatomyositis compared with polymyositis was 2.4 (CI, 1.3 to 4.2). An increased risk for malignant disease was also found in inclusion-body myositis (standardized incidence ratio, 2.4 [CI, 1.2 to 4.9]). The excess risk for malignant disease diminished with time (standardized incidence ratio, 4.4 [CI, 2.7 to 7.1] in the first year; 3.4 [CI, 2.3 to 5.1] between 1 and 3 years; 2.2 [CI, 1.3 to 3.9] between 3 and 5 years; and 1.6 [CI, 1.0 to 2.6] beyond 5 years [ P for trend, 0.002]).

CONCLUSION

The risk for malignant disease is increased in biopsy-proven dermatomyositis and polymyositis and also appears to be increased in inclusion-body myositis.

HTLV-1 and polymyositis in Jamaica

IgG antibodies to human T-cell lymphotropic virus (HTLV-1) were found in 11 of 13 (85%) Jamaican patients with idiopathic adult polymyositis. The association was first observed in 7 patients with polymyositis who were included in a control group of 100 patients with neurological and neuromuscular diseases in a serological investigation of the prevalence of HTLV-1 antibody in patients with tropical spastic paraparesis. All 7 patients with polymyositis were positive for the antibody by an enzyme-linked immunosorbent assay, confirmed by western blot. Because of this striking association a further 6 patients with polymyositis were identified and tested, 4 of whom were also seropositive for HTLV-1 antibody.

Interstitial lung disease in polymyositis and dermatomyositis. Clinical features and prognosis as correlated with histologic findings

Open lung biopsies from 14 patients and autopsy tissue from one patient with polymyositis/dermatomyositis were reviewed in an attempt to correlate histologic features with clinical, radiographic, and prognostic variables. Three major groups based on histologic patterns were identified: bronchiolitis obliterans organizing pneumonia (BOOP), usual interstitial pneumonia (UIP), and diffuse alveolar damage (DAD). Patients with BOOP had a more favorable prognosis than did patients with UIP. Patients with DAD had a uniformly poor prognosis. One patient had a cellular interstitial pneumonia and did well. Histologic subclassification of the interstitial lung disease proved to be a better predictor of survival than did the radiographic appearance or the clinical presentation. These findings suggest that there is a broader range of histologic findings in polymyositis-dermatomyositis than is suggested in the literature and subclassification may be useful for prognosis.

Polymyositis: its presentation, morbidity and mortality

A survey of 118 patients seen in the last twenty years in Newcastle upon Tyne forms the basis of this report. All of these 118 patients fulfilled clearly defined clinical, electrophysiological and pathological criteria for the diagnosis of polymyositis: muscle pain, weakness and characteristic EMG and/or muscle biopsy 55%; and characteristic muscle biopsy 17%; muscle weakness and characteristic EMG 7%; muscle weakness and pain, and raised serum CK activity in an established collagen-vascular disease 5%. A smaller group of 25 patients were selected in whom the clinical characteristics, EMG, muscle biopsy and serum enzyme levels were all completely diagnostic of polymyositis. The patients were followed for two months to twenty-six years, with a mean follow-up duration of six years. Analysis was made of the features at presentation and during the course of the illness, and of prognostic factors bearing upon the disability, response to treatment and mortality. Cases were classified according to the system of Rose and Walton (1966). Groups I, II, and III each constituted approximately one-third of the total cases, while only 8% of all cases were associated with carcinoma. The female to male ratio was 1.4:1. Though cases were seen in all age groups, the largest number was in the sixth decade. The sedimentation rate was raised in 55% of cases. Electromyography was characteristic of polymyositis in 45% of cases, and in only 11% was it normal. The serum creatine kinase activity was raised in 64% of cases. There was no correlation between the extent of these abnormalities and the degree of weakness or disability. 65% of muscle biopsies had changes with inflammatory infiltration virtually diagnostic of polymyositis. 17% of cases had a normal muscle biopsy. Most of the patients (89%) were treated with high-dose prednisone therapy, commencing with 30-100 mg/day, gradually reducing to a maintenance dose of 5-15 mg/day over two or three months. All clinical groups showed considerable improvement in average disability with time on "high dose" corticosteroid therapy, the maximum improvement occurring within the first three years. The degree of improvement in disability was considerably less in those inadequately treated, though the mortality rate was similar in the two groups. 66% of all survivors had essentially no functional disability at follow-up three or more years later, and in the majority of these cases the disease appeared to have burned itself out. 33% of cases had significant disability after three years, and in half of these the disease appeared to be still active.

Association of autoantibodies to different nuclear antigens with clinical patterns of rheumatic disease and responsiveness to therapy

Using a hemagglutination test which can detect antibodies to (a) native and denatured deoxyribonucleic acid (DNA) and (b) an extractable nuclear antigen (ENA), a comparative study of patterns of autoantibody formation has been done in systemic lupus erythematosus (SLE) and related rheumatic diseases. Antibody to native DNA was present in the serum in 96% of patients with active SLE and disappeared during remissions. Antibody to ENA was found in 86% of those patients with SLE nephritis who responded to treatment but in only 8% of those who did not. The highest titers of antibody to ENA were found in patients having a mixed connective tissue disease syndrome with features of SLE, scleroderma, and myositis. The latter syndrome was notable for the absence of renal disease and for a striking responsiveness to corticosteroid therapy. Hemagglutination testing of 277 sera from normal persons and patients with a wide variety of acute diseases other than SLE revealed the presence of antibody to native DNA in only 1.4% and antibody to ENA in only 0.4%. These results yield significant correlations among the pattern of autoimmune reactivity, the clinical form of the rheumatic disease, and responsiveness to treatment. They implicate the qualitative nature of the patient's immune response as a conditioning factor in the type of disease. Together with other correlations they may allow classification of rheumatic diseases into more biologically meaningful groups and lead to more selective methods of therapy.

Long-term survival of patients with idiopathic inflammatory myopathies according to clinical features: a longitudinal study of 162 cases

The idiopathic inflammatory myopathies are characterized by chronic muscle inflammation and involvement of internal organs, which contribute considerably to the morbidity and mortality of the disease. We conducted the current study to determine the survival data for patients with idiopathic inflammatory myopathies according to the presence of extramuscular clinical manifestations. We also determined the cumulative survival probability and the long-term prognosis and analyzed the causes of death at a single clinical immunology center.A survival analysis was performed using data for 162 patients diagnosed between 1976 and 1997 according to Bohan and Peter's criteria. Patients were followed up for a minimum of 5 years (median, 101.5 mo) or to date of death. Cumulative survival probability was calculated by the Kaplan-Meier method. The influence of extraskeletal and extramuscular involvement was analyzed as prognostic factors for death by Cox proportional hazards survival model. Eighteen disease-specific deaths occurred; pulmonary and cardiac complications were the most frequent causes of death. Global survival rates were 95%, 92%, and 89% for 1, 5, and 10 years, respectively. Analysis for clinicopathologic subgroups revealed that cancer-associated myositis had the worst prognosis, while juvenile and overlap myositis had the best prognosis. Five- and 10-year survival rates were 94.2% and 89.4% for patients with primary polymyositis and 90.1% and 86.4% for primary dermatomyositis patients, respectively. In the whole group of patients with idiopathic inflammatory myopathy, cardiac (p < 0.01) and respiratory muscle involvement (p = 0.045) were significant prognostic factors for death. In the group of patients with primary polymyositis/dermatomyositis, cardiac involvement was the main prognostic factor for death (p < 0.01). Myositis patients described in this study have higher survival rates than reported previously worldwide. We examine the reasons for the differences between the data in the current study and the available survival data in the relevant literature.

Neuromuscular diseases associated with human immunodeficiency virus infection

The types of neuromuscular diseases associated with human immunodeficiency virus (HIV) infection are described. Our classification includes: (1) six subtypes of peripheral neuropathies--namely, acute Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, mononeuritis multiplex, an axonal, predominantly sensory, painful polyneuropathy, a sensory ataxic neuropathy due to ganglioneuronitis, and an inflammatory polyradiculoneuropathy presenting as cauda equina syndrome; (2) inflammatory myopathies (e.g., polymyositis); and (3) other less common neuromuscular manifestations, such as type II muscle fiber atrophy and nemaline myopathy. Although the exact incidence of clinical and subclinical neuromuscular diseases in HIV-positive and acquired immunodeficiency syndrome (AIDS) patients is unknown, estimates vary from 15 to almost 50% of such individuals. The type of neuropathy or myopathy related to the specific stage of HIV infection, the pathogenetic mechanisms involved, and effective therapies are discussed. A neuromuscular disease not only occurs in patients with AIDS and AIDS-related complex, but it can coincide with HIV seroconversion or it can be the only clinical indication of a chronic silent HIV infection. Chronic asymptomatic HIV infection should be considered in the differential diagnosis of certain acquired inflammatory polyneuropathies or myopathies. Precautions needed when doing electromyographic studies are discussed.

Anti-Jo-1 antibody: a marker for myositis with interstitial lung disease

An autoantibody known as anti-Jo-1 antibody is found in 25% of patients with myositis. Its prevalence in patients with both myositis and cryptogenic fibrosing alveolitis was 68% (13 out of 19 patients), compared with 7.5% in patients with myositis alone (four of 53) and 3% in patients with cryptogenic fibrosing alveolitis alone (two of 62). Anti-Jo-1 antibody may be useful in indicating patients with myositis and cryptogenic fibrosing alveolitis. Raynaud's phenomenon, the sicca syndrome, and mild arthritis are also often part of the syndrome.

Prevalence and factors associated with left ventricular dysfunction in the EULAR Scleroderma Trial and Research group (EUSTAR) database of patients with systemic sclerosis

OBJECTIVES

To measure the prevalence of, and factors associated with, left ventricular (LV) dysfunction in systemic sclerosis (SSc).

METHODS

The EUSTAR database was first searched. A case-control study of a patient subset was then performed to further identify independent factors associated with LV dysfunction by simple and multiple regression.

RESULTS

Of 7073 patients, 383 (5.4%) had an LV ejection fraction (EF) of <55%. By multiple regression analysis, age, sex, diffuse cutaneous disease, disease duration, digital ulcerations, renal and muscle involvement, disease activity score, pulmonary fibrosis and pulmonary arterial hypertension were associated with LV dysfunction. In the second phase, 129 patients with SSc with LVEF <55% were compared with 256 patients with SSc with normal LVEF. Male sex (OR 3.48; 95% CI 1.74 to 6.98), age (OR 1.03; 95% CI 1.01 to 1.06), digital ulcerations (OR 1.91; 95% CI 1.05 to 3.50), myositis (OR 2.88; 95% CI 1.15 to 7.19) and use of calcium channel blockers (OR 0.41; 95% CI 0.22 to 0.74) were independent factors associated with LV dysfunction.

CONCLUSION

The prevalence of LV dysfunction in SSc is 5.4%. Age, male gender, digital ulcerations, myositis and lung involvement are independently associated with an increased prevalence of LV dysfunction. Conversely, the use of calcium channel blockers may be protective.

Treatment of antisynthetase-associated interstitial lung disease with tacrolimus

OBJECTIVE

To assess the efficacy of tacrolimus in patients with anti-aminoacyl-transfer RNA synthetase (anti-aaRS)-associated interstitial lung disease (ILD) and idiopathic inflammatory myopathy (IIM).

METHODS

Ninety-eight patients with anti-aaRS autoantibodies were identified in our IIM cohort of 536 patients. The medical records of 15 patients with anti-aaRS-associated ILD treated with tacrolimus between 1992 and 2003 were retrospectively reviewed. Pulmonary parameters of response included forced vital capacity, forced expiratory volume in 1 second, and diffusing capacity for carbon monoxide. Manual muscle testing results, serum creatine kinase (CK) levels, and the daily corticosteroid dosage were used to assess improvement in myositis. Random coefficient modeling considering polynomials of time was used to assess the clinical response to tacrolimus.

RESULTS

All patients, except for 1, who had pure ILD, had definite or probable IIM. Two patients received tacrolimus for fewer than 3 months, and their data were not analyzed. For the remaining 13 patients, the mean age at onset of ILD was 46.9 years, and the mean duration of pulmonary disease was 14.7 months. Twelve patients had anti-histidyl-transfer RNA synthetase autoantibody (anti-Jo-1) and 1 had anti-alanyl-transfer RNA synthetase autoantibody (anti-PL-12). Patients received tacrolimus for an average of 51.2 months. A significant improvement was observed in all pulmonary parameters measured. The serum CK level declined significantly, and 10 patients had either an improvement in muscle strength or maintained normal muscle strength. A statistically significant reduction in the corticosteroid dosage was also observed.

CONCLUSION

Tacrolimus is a well-tolerated and effective therapy for managing refractory ILD and myositis in anti-aaRS-positive patients.

Anti-aminoacyl-tRNA synthetase antibodies in clinical course prediction of interstitial lung disease complicated with idiopathic inflammatory myopathies

In the treatment of polymyositis and dermatomyositis (PM/DM), the complication of interstitial lung disease (ILD) is an important prognostic factor. It has been reported that autoantibodies against aminoacyl-tRNA synthetases (ARS) are strongly associated with ILD. The aim of this study is to examine the correlation between anti-ARS and the clinical course of ILD. We investigated 41 cases of PM/DM with ILD. The response of ILD to corticosteroids (CS) was determined according to the change in respiratory symptoms, image findings, and pulmonary function between, before and 2 months after the treatment. Anti-ARS (anti-Jo-1, PL-7, PL-12, EJ, OJ and KS) antibodies were screened with the RNA immunoprecipitation assay. In the stratification into ILD-preceding, simultaneous and myopathy-preceding types, anti-ARS antibodies were significantly frequent in the ILD-preceding type (p < 0.05). In the stratification into anti-ARS-positive and negative groups, the response of ILD to CS was significantly better in the positive group (p < 0.05). However, recurrence of ILD was significantly more frequent in the positive group (p < 0.01), and 2 year prognoses of pulmonary function (%VC and %DLCO) were not different between the two groups. In conclusion, screening of anti-ARS may be useful to predict late-onset myopathy in ILD-preceding patients and to predict the clinical course of ILD in PM/DM patients.

The precipitating antibody to an acidic nuclear protein antigen, the Jo-1, in connective tissue diseases. A marker for a subset of polymyositis with interstitial pulmonary fibrosis

The clinical significance of antibodies to the Jo-1 antigen in connective tissue diseases was studied. Clinical diagnoses of 11 patients who had anti-Jo-1 antibody were: polymyositis 8, dermatomyositis 1, and overlap syndrome 2 (polymyositis--systemic lupus erythematosus 1, polymyositis--scleroderma 1). All the patients who had anti-Jo-1 antibody showed interstitial pulmonary fibrosis, and in 2 patients anti-Jo-1 antibodies were detected before the appearance of lung disease.

Interstitial lung disease in polymyositis and dermatomyositis: analysis of six cases and review of the literature

Interstitial pneumonitis may be the presenting manifestation of polymyositis-dermatomyositis, or may occur later in the evolution of the disease. The clinical picture is characterized by non-productive cough, dyspnea and hypoxemia. The chest radiograph demonstrates interstitial infiltrates with predilection for the lung bases, often with an alveolar pattern in addition. The histopathologic features are those of organizing and interstitial pneumonitis and pleuritis, with variable fibrosis. In the present series, the patients with mixed alveolar and interstitial infiltrates on chest radiograph and organizing pneumonia and bronchiolitis obliterans in addition to interstitial pneumonitis. In one patient evolution from pulmonary inflammation to interstitial fibrosis was demonstrated. The etiology of primary lung disease in PM-DM is not known, but cell-mediated autoimmunity to an unidentified component of lung tissue is suggested. Including the present series, 50 percent of patients have responded favorably to corticosteroids with decreased dyspnea, clearing of the chest radiograph and improved pulmonary function tests.

The heart and cardiac conduction system in polymyositis-dermatomyositis: a clinicopathologic study of 16 autopsied patients

We reviewed the clinical records of 16 patients with polymyositis-dermatomyositis syndromes autopsied at The Johns Hopkins Hospital to determine the nature and extent of cardiac involvement and its correlation with the severity of disease as a whole. The adult patients ranged in age from 32 to 84 years (average 56); the 2 children were aged 2 and 10 years. The duration of disease ranged from 1 to 72 months (average 21). Seven patients had dermatomyositis, 5 had dermatomyositis with malignancy, 2 had childhood dermatomyositis, and 2 had an overlap syndrome. Seven patients had clinical evidence of congestive heart failure, 4 of whom had microscopic evidence of myocarditis. Two patients had bundle branch block; in 1 there was direct involvement of the conduction system by myositis and contraction band necrosis. Evidence of active myocarditis was present in 4 patients (25%); all had congestive failure. Focal myocardial fibrosis was present in 4 patients. Vascular alterations were present in the coronary arteries in 5 patients (31%). Three had active vasculitis, 1 had intimal proliferation, and 1 had medical sclerosis with calcification. All patients with active myocarditis had skeletal muscle involvement. Nine patients had myositis without myocarditis. There was no correlation of overall severity of the disease with the presence or absence of active myocarditis. The present study shows that cardiac involvement may be common in polymyositis; congestive failure or conduction abnormalities arising in this setting may be indicative of myocarditis.

Prognostic factors in polymyositis/dermatomyositis. A computer-assisted analysis of ninety-two cases

An effort was made to identify all patients with polymyositis/dermatomyositis (PM/DM) admitted to hospitals in Israel from 1956-1976. The diagnosis of PM/DM was retrospectively reviewed in 92 (46 definite, 26 probable, and 20 possible) cases. The most common complaints and physical findings in the course of the disease were muscle weakness (86 patients), rash (53 patients), arthritis or arthralgia (39 patients), and dysphagia (35 patients). Elevated serum aldolase levels were found in 64% of the patients for whom data were available; 92% had abnormal electromyogram results, and 60.9% had muscle histopathology consistent with PM/DM. Malignancy was diagnosed in 13 patients. Malignancy, ischemic heart disease, and pulmonary complications were the most common causes of death. The actuarial survival curve was heterogeneous, with an accelerated mortality during the first year after diagnosis and a slower mortality during the following 7 years. Independent unfavorable prognostic signs were: failure to induce remission, leukocytosis, fever, older age, a shorter disease history, and dysphagia.

Hepatic manifestations of autoimmune rheumatic diseases

Hepatic manifestations in autoimmune disease include chronic active hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis, and nodular regenerative hyperplasia. These diseases are rare and may occur concomitantly or serially. Clinicians must be aware of the possibility of liver disease so that it can be treated as soon as possible.

Torque teno virus (TTV): current status

Torque teno virus (TTV), currently classified into the family Circoviridae, genus Anellovirus, was first found in a patient with non-A-E hepatitis. TTV has a single stranded circular DNA of approximately 3.8 kb. TTVs are extraordinarily diverse, spanning five groups including SANBAN and SEN viruses. Torque teno mini virus (TTMV) with approximately 2.9 kb genome also has wide variants. Recently, two related 2.2- and 2.6-kb species joined this community. Recombinations between variants are frequent. This extensive TTV diversity remains unexplained; it is unclear how TTVs could be viable, and why they require such genetic variation. An unequivocal culture system is still not available. TTVs are ubiquitous in > 90% of adults worldwide but no human pathogenicity of TTV has been fully established. Epidemiological surveys need to specify the variants being studied and clinical targets, and must calibrate the sensitivity of the assay used. Potentially interesting observations include a higher viral load in patients with severe idiopathic inflammatory myopathies, cancer and lupus. Active replication was also found in infants with acute respiratory diseases. TTV/TTMV-related viruses were found in chimpanzees, apes, African monkeys and tupaias, and also in chickens, pigs, cows, sheep and dogs. Experimentally, rhesus monkeys were persistently infected by TTV, but only 1/53 chimpanzees. TTV transcribes three species of mRNAs, 3.0-, 1.2- and 1.0-kb in the ratio of 60:5:35. Recently, at least three mRNAs were shown in chicken anaemia virus. The genomic region -154/-76 contains a critical promoter. TTV seems to have at least three proteins; however, the definite functions of these proteins await further research work.

Nonthyroid causes of extraocular muscle disease

Extraocular muscle involvement in orbital disease is most frequently seen as a feature of thyroid orbitopathy (Graves' disease). However, a wide range of other conditions may alter the size, shape, and function of these muscles, with characteristic clinical manifestations or abnormalities visible on orbital imaging. The differential diagnosis of muscle disease can be narrowed by careful analysis of clinical features and ancillary tests. Imaging facilitates recognition in many cases, but in some instances, accurate diagnosis requires biopsy. This review highlights the differential diagnoses for diseases of extraocular muscles based on the clinical and investigative records of 103 patients at our institution combined with data from the world literature. We found that the most common nonthyroid causes of muscle disease were inflammatory, vascular, and neoplastic processes (in decreasing order of frequency). Emphasis is placed on investigations that provide a logical approach to, and appropriate management of, disease of the extraocular muscles.

COVID-19 and the nervous system

A pandemic due to novel coronavirus arose in mid-December 2019 in Wuhan, China, and in 3 months' time swept the world. The disease has been referred to as COVID-19, and the causative agent has been labelled SARS-CoV-2 due to its genetic similarities to the virus (SARS-CoV-1) responsible for the severe acute respiratory syndrome (SARS) epidemic nearly 20 years earlier. The spike proteins of both viruses dictate tissue tropism using the angiotensin-converting enzyme type 2 (ACE-2) receptor to bind to cells. The ACE-2 receptor can be found in nervous system tissue and endothelial cells among the tissues of many other organs.Neurological complications have been observed with COVID-19. Myalgia and headache are relatively common, but serious neurological disease appears to be rare. No part of the neuraxis is spared. The neurological disorders occurring with COVID-19 may have many pathophysiological underpinnings. Some appear to be the consequence of direct viral invasion of the nervous system tissue, others arise as a postviral autoimmune process, and still others are the result of metabolic and systemic complications due to the associated critical illness. This review addresses the preliminary observations regarding the neurological disorders reported with COVID-19 to date and describes some of the disorders that are anticipated from prior experience with similar coronaviruses.