A Case of Acute Disseminated Encephalomyelitis Accompanying Intussusception Associated with Mycoplasma pneumoniae Infection

Acute disseminated encephalomyelitis (ADEM) is an inflammatory demyelinating disorder of the central nervous system (CNS), with a relatively high incidence in the pediatric population [1]. Although the precise pathogenesis is unknown, ADEM is presumed to be an autoimmune disorder stimulated by a systemic infection or vaccination [2]. Aberrant immune reactions in ADEM are associated with several pathogens, including viruses (such as varicella, influenza virus, Epstein-Barr virus, enterovirus, and severe acute respiratory syndrome coronavirus 2) and bacteria (such as Mycoplasma pneumoniae and Streptococcus) [2]. Intussusception is one of the most common causes of intestinal obstruction [3]. The pathogenesis of intussusception without anatomical leading points remains unknown. However, intestinal lymphoid hyperplasia stimulated by infectious pathogens may cause intussusception [3]. We present an unusual case of ADEM accompanied by intussusception secondary to M. pneumoniae infection. A previously healthy 17-month-old Korean girl was referred to our department with poor feeding, vomiting, decreased activity, and cyclic irritability following a 4-day prodromal illness consisting of cough, sputum, and mild fever. On admission, her body temperature was 37.7°C. Auscultation of both lung fields and the abdomen revealed bilateral crackles and decreased bowel sounds, respectively. Chest radiography revealed showed bilateral perihilar interstitial infiltrates (Fig. 1A). Her initial blood test result revealed no abnormalities, except for leukocytosis (12.3 × 10/L white blood cells) and a mildly increased serum C-reactive protein level (0.7 mg/dL; reference range, < 0.5 mg/dL). Multiplex real-time polymerase chain reaction (PCR) results for respiratory viral and bacterial pathogens in nasopharyngeal aspirate were negative, except for M. pneumoniae. The result of an M. pneumoniae-specific immunoglobulin M antibody test was positive (3.30 immune status ratio [ISR]; reference range < 0.8 ISR). Although the patient did not have stool mixed with blood and mucus, gastrointestinal ultrasonography was performed because of cyclic irritability. An ultrasound image showed the typical findings of intussusception (Fig. 1B and C) and the enlargement of several lymph nodes within the intussuscipiens, which may have been a leading point. The condition was diagnosed as ileocolic intussusception. She was treated with roxithromycin for M. pneumoniae and non-operative reduction using pneumatic pressure by enema for