Chapter 14 - Gastrointestinal Involvement in Inflammatory Myositis
Introduction
Inflammatory myopathies (IMs) are a group of rare immune-mediated diseases characterized by proximal muscle weakness and mononuclear cell inflammation of the skeletal muscle [1]. IMs are the largest group of potentially treatable myopathies and form a heterogeneous group of disorders. We may classify them into five subtypes according to their clinicopathologic features: dermatomyositis (DM), polymyositis (PM), necrotizing autoimmune myositis, inclusion body myositis (IBM), and overlap myositis (OM). The precise diagnosis of the subtype and the differential diagnosis from other diseases that have similar signs and symptoms are fundamental, as each subtype has a different prognosis and therapeutic response [2], [3].
The incidence of IM is between 3.7 and 7.7 cases per million, depending on the diagnostic inclusion criteria and population studied [4]. DM is the most common and affects both children and adults. PM is the least common and generally occurs after the second decade of life. IBM is the most frequent IM in patients over the age of 50. OM has only been recognized since 2005.
The gastrointestinal (GI) complications of IM are often neglected, and few studies have been specifically focused on managing these patients [5].
Section snippets
Dysphagia
Dysphagia caused by pharyngeal and esophageal abnormalities has been reported in 32–84% of patients with myositis and may be the only symptom at the time of presentation [6]. The pharynx and upper esophageal sphincter are affected because, like peripheral muscle, they are composed of skeletal muscle.
The causes of dysphagia in patients with IM are heterogeneous and may be related to an inadequate pharyngeal contraction, a poor relaxation of the cricopharyngeus muscle, or a reduced hyolaryngeal
Gastric Involvement
Gastric emptying can be delayed in PM and DM. This suggests malfunction of the smooth muscle of the upper GI tract [13]. These patients tend to have active disease, complain of reflux, and respond to antireflux measures and treatment of the myositis. Manometry may reveal a reduced distal esophageal sphincter resting pressure with normal relaxation and nonperistaltic low-amplitude simultaneous contraction. Endoscopy may reveal esophagitis or stricture formation [14].
When we assess gastric and
Gastrointestinal Vasculitis and Inflammation
The association of juvenile DM with severe GI tract involvement due to vasculitis of the bowel wall is well known [16], [17]. Few cases have been reported in adults [18]. DM may be associated with a vasculitis involving the GI tract. This may be a noninflammatory acute endarteropathy with arterial and venous intimal hyperplasia and occlusion of vessels by fibrin thrombi in the mucosa, submucosa, and serosal layers of the bowel. This narrowing and occlusion of small- and medium-sized arteries
Pneumatosis Cystoides Intestinalis
Pneumatosis intestinalis (PI) has been associated with several autoimmune diseases, most commonly with systemic sclerosis, but has been also reported in patients with systemic lupus erythematosus, Sjogren's syndrome, and IMs. The etiology of PI is often unclear although evidence exists for the contribution of increased intraluminal pressure due to GI dysmotility, overgrowth of anaerobic bacteria, retroperitoneal dissection of pulmonary gas, and disruption of mucosal integrity [24], [25].
In
Overlap With Inflammatory Bowel Disease
The coexistence of IM with inflammatory bowel disease (IBD) has been reported in isolated cases [31]. IM is more commonly associated with Crohn disease (CD) than ulcerative colitis (UC). Both of them have many extraintestinal manifestations, but muscular involvement is infrequent. In patients diagnosed with UC, myositis may precede clinical expression of colitis and recur during acute exacerbations of IBD [32], [33].
IM may be an infrequent extraintestinal complication in patients diagnosed with
Overlap With Coeliac Disease
Coeliac disease has been occasionally reported in patients with IMs. In 2007, Selva-O'Callaghan et al. evaluated the presence of celiac disease and related antibodies (antigliadin, antitissue transglutaminase, and antiendomysial antibodies) in 51 patients with IMs. Three (6%) patients showed jejunal biopsies diagnostic for coeliac disease, and all had histological normalization after a gluten-free diet. Seventeen patients (31%) were positive for antigliadin antibodies, and the frequency was
Association With Chronic Viral Infections
The most frequent environmental etiopathogenic factors associated with myositis are infections. Hepatitis B virus (HBV) is associated with the development of several extrahepatic manifestations including vasculitis, glomerulonephritis, polyarthralgia and arthritis, PM, and DM [39], [40]. Evidence of active HBV replication in the vascular endothelium of a patient with PM has been reported [41]. PM may be triggered by HBV. An acute exacerbation of HBV may be induced by withdrawal from steroids
Diagnosis and Differential Diagnosis
The diagnosis of IM-related GI involvement is based on the clinical aspects and complementary explorations such as endoscopy, cine esophagram, VF, and manometry [5], [9], [10].
There is a broad differential diagnosis, including certain muscular dystrophies, metabolic myopathies, drug- or toxin-induced myotoxicity, neuropathies, and infections [50], [51]. An alternative diagnosis should be always considered in patients with PM, especially in those patients who showed a lack of response to
Therapeutic Management
Corticosteroids are the mainstay of treatment, although their efficacy has not been fully established in randomized, placebo-controlled trials. Other immunosuppressive drugs that can be used include methotrexate, azathioprine, cyclophosphamide, and cyclosporin A [54]. Anti-TNF therapy may be considered in refractory PM/DM [55], [56]. According to a double-blind, placebo-controlled study, intravenous immunoglobulin may be effective in muscle strength and rash in DM and provide dramatic
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