Mycoplasma pneumoniae-associated mild encephalitis/encephalopathy with a reversible splenial lesion: report of two pediatric cases and a comprehensive literature review

Abstract

BackgroundNo literature review exists on Mycoplasma pneumoniae-associated mild encephalitis/encepharopathy with a reversible splenial lesion (MERS).Methods M.pneumoniae-associated MERS cases were searched till August 2016 using PubMed/Google for English/other-language publications and Ichushi (http://www.jamas.or.jp/) for Japanese-language publications. Inclusion criteria were children fulfilling definition for encephalitis, M.pneumoniae infection, and neuroimaging showing hyperintensity in the splenium of the corpus callosum (SCC) alone (type I) or SCC/other brain areas (type II).ResultsWe described two children with type I and II M.pneumoniae-associated MERS. Thirteen cases found by the search and our 2 cases were reviewed. Mean age, male/female ratio, duration of prodromal illness was 8.3 years, 1.5 and 3.5 days. The most common neurological symptom was drowsiness, followed by abnormal speech/behavior, ataxia, seizure, delirium, confusion, tremor, hallucination, irritability, muscle weakness, and facial nerve paralysis. Fever was the most common non-neurological symptom, followed by cough, headache, gastrointestinal symptoms, headache, lethargy and dizziness. Seizure and respiratory symptoms were less common. All were diagnosed for M.pneumoniae by serology. Cerebrospinal fluid (CSF) M.pneumoniae was undetectable by PCR in the 3 patients. Three patients were clarithromycin-resistant. Leukocytosis, positive C-reactive protein, hyponatremia, CSF pleocytosis and slow wave on electroencephalography frequently occurred. All except 2 were type I MERS. Neuroimaging abnormalities disappeared within 18 days in the majority of patients. All type I patients completely recovered within 19 days. Two type II patients developed neurological sequelae, which recovered 2 and 6 months after onset.ConclusionsPrognosis of M.pneumoniae-associated MERS is excellent. Type II MERS may increase a risk of neurological sequelae.

Manifestaciones neuroftalmológicas como complicación de una infección por Mycoplasma pneumoniae y desarrollo posterior de una encefalitis aguda diseminada

“…El método gold standard para el diagnóstico de M. pneumoniae es la PCR en sangre y LCR, aunque generalmente se realiza por serología (IgM e IgG), a pesar de baja sensibilidad para IgM descrita en algunos estudios (32-77%) 6 .…”

Commentary: Mycoplasma pneumoniae-associated mild encephalitis/encephalopathy with a reversible splenial lesion: Report of two pediatric cases and a comprehensive literature review

“…Hyponatremia is proposed as a possible cause of MERS 25 . Since it occurred in only 31.0% -60.0% 3,27,28 of MERS cases although high prevalence (83.3 %) was reported 25 , hyponatremia may be a predisposing but not causative factor. Electrolyte-water imbalance 25 by arginine vasopressin suppression 29 is proposed as a cause, but this awaits further investigations.…”

“…As MERS by other etiologies, M.pneumoniae-associated MERS predominantly occurs in children (2-14 years) 3 . Mean age (8.3 years) of children with M.pneumoniae-associated MERS 3 is similar to that (8.7 years) of those with M.pneuminiae-associated encephalitis 4 , suggesting that age-related immune dysfunction may predispose to MERS.…”

“…As MERS by other etiologies, the organism was not detected in cerebrospinal fluid (CSF) of the majority of patients with M.pneumoniae-associated MERS 3 , suggesting that systemic factors rather than direct invasion of the organism in central nervous system may play a pathogenic role for MERS. Since SCC receives arterial supply from the vertebrobasilar system 26 , factors in serum/CSF may affect its function.…”

“…Prevalence of MERS was 10.3 % of children with status epilepticus 1 and 15.6 % of those with encephalitis in a Japanese nationwide study 2 . We reviewed clinical characteristics of all reported pediatric cases of Mycoplasma pneumoniae (M.pneumoniae)-associated MERS 3 . Fever is the most common non-neurological symptom, while more than half of the cases have no respiratory symptoms.…”