Neurology of inflammatory bowel disease.

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions affecting the digestive system, comprising two main distinctive entities, ulcerative colitis (UC) and Crohn's disease (CD). Besides gastrointestinal manifestations, IBD causes extraintestinal manifestations in the central and peripheral nervous system. The incidence of neurological complications in IBD ranges from 0.25% to 47.5%. The pathophysiology of neurological manifestations of IBD is mostly immune mediated, but dysfunction of the brain-gut axis, arterial and venous thromboembolism, infections, nutritional deficiencies and side-effects of medications (steroids, metronidazole, sulfasalazine, anti-TNF-α, anti-integrin antibodies) are other contributory mechanisms. Patients with IBD have an increased risk of arterial and venous stroke, mainly during periods of exacerbations. Vasculitis is extremely rare. There is a bidirectional association between multiple sclerosis and IBD, with a relative risk for comorbidity of 1.54, being 1.53 for the risk of multiple sclerosis in IBD and 1.55 for the risk of IBD in multiple sclerosis patients. Anti-TNF-α therapy is contraindicated in the treatment of patients who have both IBD and multiple sclerosis. Demyelinating disorders can also be a rare complication of anti-TNF-α therapy. Optic neuritis, transverse myelitis, progressive myelopathy, central nervous system infections, epilepsy and encephalopathy are among other uncommon neurological complications. Peripheral nervous system manifestations include peripheral neuropathy, either demyelination and axonal, myasthenia gravis and polymyositis/dermatomyositis and localized forms of myositis.