Clinically mild encephalitis/encephalopathy with a reversible splenial lesion associated with Mycoplasma pneumoniae infection

Abstract

BackgroundClinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is a clinico-radiological syndrome characterized by transient mild symptoms of encephalopathy and a reversible lesion in the splenium of the corpus callosum on magnetic resonance imaging (MRI). It is often triggered by infection. The common pathogens of MERS are viruses, especially influenza virus. However, Mycoplasma pneumoniae (M.pneumoniae) are relatively rare pathogens for MERS.Case presentationHere we report two paediatric cases of M.pneumoniae infection-induced MERS. The diagnosis of M.pneumoniae infection was established based on polymerase chain reaction (PCR) and specific serum antibodies (IgM). Both of the two patients presented with mild encephalopathy manifestations and recovered completely within a few days. The initial MRI showed a lesion in the central portion of the splenium of the corpus callosum, which completely resolved on the seventh and eighth day after admission for case 1 and case 2. Lumbar puncture was performed in both patients, which revealed no pleocytosis. In case 1, the patient had hyponatremia, peripheral facial nerve paralysis, and rash. To the best of our knowledge, it is the first MERS case associated with peripheral nerve damage. In case 2, interleukin-6(IL-6) was moderately increased in the cerebrospinal fluid (CSF). It suggested that IL-6 may play a role in the pathogenesis of M.pneumoniae-induced MERS.ConclusionOur study enriches the available information on the pathogens of MERS and provides valuable data for better understanding of this syndrome.

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

“…All except one case [5] were reported from Asia; Japan [12, 15–20] and China [13, 14], suggesting a role of racial factor(s) for M.pneumoniae -associated MERS. As M.pneumoniae -associated encephalitis [7–10], M.pneumoniae -associated MERS predominantly occurs in children aged 2–14 years.…”

“…However, hyponatremia occurs in less than a half of M.pneumoniae -associated MERS patients, similar to MERS by other causes (37–83 %) [3, 14, 26, 36, 38], suggesting that hyponatremia may be a modulator but not essential for development of the SCC lesions. As M.pneumoniae -associated encephalitis [7, 9, 33], PCR rarely detected M.pneuminiae in CSF of M.pneumoniae -associated MERS [13, 20], suggesting indirect mechanisms such as immune-mediated mechanism [1] rather than direct invasion of M.pneumoniae, leading to the SCC lesions. The levels of CSF IL-6 were increased in MERS due to M.pneumoniae [13] and other causes [39].…”

“…As M.pneumoniae -associated encephalitis [7, 9, 33], PCR rarely detected M.pneuminiae in CSF of M.pneumoniae -associated MERS [13, 20], suggesting indirect mechanisms such as immune-mediated mechanism [1] rather than direct invasion of M.pneumoniae, leading to the SCC lesions. The levels of CSF IL-6 were increased in MERS due to M.pneumoniae [13] and other causes [39]. IL-6 induces the SCC injury [40].…”

Mild Encephalitis/Encephalopathy with a Reversible Splenial Lesion Due to Respiratory Syncytial Virus: Case Report

“…A genetic theory has also been suggested because most patients with MERS are of Asian origin [8]. This is the second etiology of acute encephalitis in Japanese children [9].…”

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

“…These factors enhance permeability of blood-brain barrier 33 , resulting in neuroinflammation, which renders microglia in the CC release proinflammatory cytokines and ROS. In fact, the levels of IL-6 were increased in cerebrospinal fluid (CSF) of children with MERS due to M.pneumoniae 34 …”