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Table of Contents    
Year : 2022  |  Volume : 70  |  Issue : 4  |  Page : 1746-1747

Mild Encephalitis/Encephalopathy with a Reversible Splenial Lesion Coincidents with Bickerstaff Brainstem Encephalitis

Department of Neurology, Juntendo University School of Medicine, Bunkyo, Tokyo, Japan

Date of Submission08-Apr-2021
Date of Decision19-Feb-2022
Date of Acceptance09-Mar-2022
Date of Web Publication30-Aug-2022

Correspondence Address:
Taiji Tsunemi
Department of Neurology, Juntendo University, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.355132

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How to cite this article:
Shimada T, Sano M, Tsunemi T, Hattori N. Mild Encephalitis/Encephalopathy with a Reversible Splenial Lesion Coincidents with Bickerstaff Brainstem Encephalitis. Neurol India 2022;70:1746-7

How to cite this URL:
Shimada T, Sano M, Tsunemi T, Hattori N. Mild Encephalitis/Encephalopathy with a Reversible Splenial Lesion Coincidents with Bickerstaff Brainstem Encephalitis. Neurol India [serial online] 2022 [cited 2022 Oct 2];70:1746-7. Available from: https://www.neurologyindia.com/text.asp?2022/70/4/1746/355132

After several days of fever, a 74-year-old male began unable to walk well. His pneumonia was improved by antibiotics, but he became somnolent and developed Cheyne–Stokes respiration. He had gaze-evoked downbeat nystagmus, limb and truncal ataxia, and jerky myoclonus. He was positive for the anti-ganglioside GM-1 antibody. Cerebrospinal fluid (CSF) examination revealed pleocytosis with elevated levels of myelin basic protein (MBP) and interleukin-6 (IL-6). Brain magnetic resonance imaging (MRI) revealed cytotoxic edema at the splenium of the corpus callosum (SCC) [Figure 1]a and [Figure 2]b and slight enhancement at the left cerebellar flocculus [Figure 1]c. The patient was diagnosed with mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) and Bickerstaff brainstem encephalitis (BBE). Although the SCC lesion naturally disappeared on day 8 [Figure 1]d and the nystagmus was alleviated, other neurological symptoms persisted. The intravenous administration of methylprednisolone led to complete clinical and radiological recovery [Figure 1]e and [Figure 1]f.
Figure 1: Brain MRI findings. Brain MRI revealed restriction on diffusion-weighted image (DWI) at the splenium of the corpus callosum (SCC) (a: white arrow) and reduction in apparent diffusion coefficient (ADC) maps (b: white thin arrow) at the SCC. Contrast-enhanced T1-weighted imaging showed slight enhancement around the left cerebellar flocculus (c: black arrowhead). The lesion at the SCC disappeared on day 8 (d: black arrow) without immunotherapy and then completely disappeared after intravenous methylprednisolone (IVMP) (e: red arrow). The lesion in the left cerebellar flocculus also disappeared after IVMP (f: red arrowhead) (a–c: day 1; d: day 8; e, f: day 15)

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MERS is a rare self-limited clinical radiological syndrome characterized by a reversible lesion in the SCC[1] and various clinical presentations within 1 week of fever, generally caused by infections.[2] Systemic cytokinemia leads to edema in neurons, glial cells, or myelin sheaths in SCC.[2] Our case is unique in that he had a cerebellar flocculus lesion, prolonged symptoms, and elevated MBP levels in CSF, which indicates myelin breakdown usually seen in BBE.[3] This case highlights that MERS can be associated with autoimmune encephalitis,[4] suggesting that an immune-mediated mechanism, at least in some cases, may underlie this disorder.

Declaration of patient consent

We have confirmed that we have read the journal's position on issues involved in ethical publication and have affirmed that this report is consistent with those guidelines. Written informed consent was obtained from the patient for participation and publication of this case report.


We thank all members of the department of neurology at Juntendo University for useful discussion.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Yuan J, Yang S, Wang S, Qin W, Yang L, Hu W. Mild encephalitis/encephalopathy with reversible splenial lesion (MERS) in adults-a case report and literature review. BMC Neurol 2017;17:103. doi: 10.1186/s12883-017-0875-5.  Back to cited text no. 1
Tetsuka S. Reversible lesion in the splenium of the corpus callosum. Brain Behav 2019;9:e01440. doi: 10.1002/brb3.1440.  Back to cited text no. 2
Odaka M, Yuki N, Yamada M, Koga M, Takemi T, Hirata K, et al. Bickerstaff's brainstem encephalitis: Clinical features of 62 cases and a subgroup associated with Guillain-Barre syndrome. Brain 2003;126:2279-90.  Back to cited text no. 3
Kaminski JA, Pruss H. N-methyl-d-aspartate receptor encephalitis with a reversible splenial lesion. Eur J Neurol 2019;26:e68-9.  Back to cited text no. 4


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