Kawasaki disease complicated with reversible splenial lesion and acute myocarditis

Kawasaki disease, a systemic vasculitis of unknown etiology, develops frequently in infants and demonstrates a variety of clinical symptoms during the disease course. The most important complication, coronary artery lesions, is found in 15-25% of untreated patients. Meanwhile, acute myocarditis, another complication that can occur during the acute phase of severe systemic vasculitis, has been found in more than 50% of affected individuals when asymptomatic cases are included. However, cases that require treatment are rare as reported by Yoshikawa et al. (Circ J 70:202-205, 2006). As for neural complications, aseptic meningitis is well known, but it is extremely rare for these patients to develop encephalitis or encephalopathy as reported by Imai et al. (Jpn Soc Emerg Pediatr 8:50-55, 2009). Recently reported magnetic resonance images (MRIs) have shown reversible lesions in the median splenium of patients complicated with encephalitis or encephalopathy. Reversible lesions have also been observed after the administration of an antiepileptic agent, drastic weight loss, and development of metabolic abnormalities as reported by Massimo et al. (Neuroradiology 49:541-544, 2007) and Tada et al. (Neurology 63:1854-1858, 2004). Aggressive therapy for such lesions is not considered necessary because most disappear without neurologic aftereffects. However, the clinical significance and pathogenesis of the condition remain largely unknown. We present the first known report of a Kawasaki disease case complicated with acute myocarditis and mild encephalitis/encephalopathy with a reversible splenial lesion (MERS). These findings may be valuable for the diagnosis and treatment of affected patients.