Skip to main content
main-content

01.12.2017 | Case Report | Ausgabe 1/2017 Open Access

BMC Neurology 1/2017

Mild encephalitis/encephalopathy with reversible splenial lesion (MERS) in adults-a case report and literature review

Zeitschrift:
BMC Neurology > Ausgabe 1/2017
Autoren:
Junliang Yuan, Shuna Yang, Shuangkun Wang, Wei Qin, Lei Yang, Wenli Hu
Abbreviations
ADC
Apparent diffusion coefficient
ADEM
Acute disseminated encephalomyelitis
CSF
Cerebrospinal fluid
EEG
Electroencephalogram
MERS
Mild encephalitis/encephalopathy with reversible splenial lesion
SCC
Splenium of the corpus callosum

Background

Tada et al. first identified the concept of mild encephalitis/encephalopathy with reversible splenial lesion (MERS) as a rare clinico-radiological syndrome in 2004 [1, 2]. In general, patients with MERS presented with mild central nervous system symptoms such as consciousness disturbance, seizures and headache and recovered completely within a month [1, 3]. MERS is divided into two types according to the lesion location. MERS type I, the typical form, most involves a singular lesion in the midline of the splenium of the corpus callosum (SCC), while MERS type II most commonly presents lesions in the symmetrical cerebral white matter or the anterior aspect of the corpus callosum with similar signal manifestations [4, 5]. The typical magnetic resonance imaging (MRI) features are transient high-signal-intensity on T2-weighted images (T2WI), fluid-attenuated inversion recovery images (FLAIR), and diffusion-weighted images (DWI), decreased apparent diffusion coefficient (ADC) value of the lesion on ADC maps, and hyper-isointense signals on T1-weighted imaging (T1WI) sequences without contrast enhancement [1, 4, 6]. Previous studies have identified that MERS can be triggered by infection including influenza virus [7], rotavirus [8], mumps virus [9], Mycoplasma pneumoniae [10] or Legionella pneumophila [11]. In addition to infection, MERS has also been reported to be associated with the administration of antiepileptic drugs [1214].
Many child-onset MERS cases have been reported, most in Asia, especially Japan [1, 15]. However, adult-onset MERS is relatively rare. Here we reported a case of adult-onset MERS with acute urinary retention. It has been speculated that the characteristics of MERS in adults are different from that in children. So we utilized this opportunity to review the literature on adult-onset MERS in order to describe the clinico-radiological features and establish a clinical position of the disease.

Methods

Case presentation

A previously healthy 37-year-old man was admitted to our hospital due to a 9-day history of headache and vomiting. Ten days prior to admission, he suddenly developed a fever of 40 °C, diarrhea and headache. After taking oral antipyretics, he still had a fever of 38–39 °C. Three days before admission, his body temperature returned to normal. Two days before admission, he suffered acute urinary retention and was treated by temporary transurethral catheterization at another hospital. One day before admission, he came to our hospital for acute urinary retention and the catheter was kept. Neurological examination revealed nuchal rigidity positive. Chemistry panel and urine analysis showed no abnormalities except for an elevated blood white cell counts (10.99 × 109/L), C-reactive protein level (9.41 mg/L) and decreased serum sodium (131.8mml/L). Routine immunological screening and tumor markers were negative. Lumbar puncture showed an elevated cerebrospinal fluid (CSF) pressure of 190mmH2O. CSF examination demonstrated an increase in white blood cells (97/ul) and protein content (124 mg/dl). The CSF etiological examination was negative. Oligoclonal bands, IgG index and myelin basic protein were within the normal ranges in CSF. Paraneoplastic antibodies were negative. Cranial MRI scans taken on the day after admission showed abnormal signals in SCC, which was hyperintense on T2WI and DWI imaging, decreased on ADC, isointense on T1WI with no contrast enhancement (Fig. 1). The plain and enhancement spinal cord MRI showed no obvious abnormalities. He received intracranial pressure reduction, antiviral, anti-inflammatory and experimental anti-tuberculosis. His urinary retention and fever resolved within 10 days. The follow-up MRI scan taken 14 days after the initial examination showed previous lesion disappeared (Fig. 2). He was discharged home without neurological complications. The final diagnosis was MERS with acute urinary retention.

Literature search and selection

To better understand the characteristics of adult-onset MERS, we performed a literature search to identify other reports (reviews, case reports or case series) from Januarary 2004 to March 2016, using the PubMed and web of science databases with the following terms, ‘mild encephalitis/encephalopathy with reversible splenial lesion’/‘MERS’/‘reversible splenial lesion’. All pertinent English language articles were retrieved. A hand-search by reviewing the reference sections of the retrieved articles was also performed. The non-English language articles, child-onset MERS reports and not getting full-text articles were excluded. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline on selection process.

Data extraction

Two investigators collected data from the selected articles. The following information were extracted: last name of the first author, country where the study was performed, the reported patient’s age, gender, CNS symptoms, neurological examination, etiology, auxiliary examination, therapy and outcome.

Results of literature review

A total of 435 articles between Januarary 2004 and March 2016 were identified by preliminary electronic literature search and hand search. The selection process was presented in Fig. 3. The characteristics of the included cases were presented in Table 1 and Table 2.
Table 1
Information of 29 adult-onset MERS cases
Reported by, location, reference
Case no.
Sex, age (years)
symptomsis
Neurological examination
Etiology
Beijing Chaoyang Hospital, China
1
M, 37
Fever, UT
cervical rigidity (+)
NQ
Tada et al. [1] Japan
2
F, 59
Fever, vertigo, lethargy
NS
NQ
3
F, 18
Fever, seizure, delirium
NS
NQ
4
M, 19
Fever, cough, delirium, seizure
NS
NQ
5
F, 25
Fever, vesicular, headache, drowsiness, nausea
NS
VZV
6
M, 22
Fever, hallucination, delirium
NS
NQ
Jun-ichi et al. [22] Japan
7
M, 31
Headache, fever, drowsiness, disorientation, memory disturbance
drowsiness, disorientation, memory disturbance
NQ
Jeong-Seon et al. [6] Korea
8
M, 59
Dysarthria, drowsiness,fever
Normal
NQ
Nida Tascilar et al. [27] Turkey
9
F, 26
Fever, headache, phonophobia, photophobia, dizziness, UT
Neck stiffness (+), positive Kernig’s sign, right truncal and gait ataxia
NQ
Makiko et al. [28] Japan
10
F, 23
Fever, headache, UT
Unsteady gait, patellar tendon reflexes, plantar reflexes, abdominal wall reflexes diminished
NQ
Henning Vollmann et al. [29] Germany
11
M, 42
Fever, vomit, headache
Mild ataxia, disturbance of gait
Tick-bites
Dimitri Renard et al. [30] France
12
M, 43
Stuporous state
GCS E4M5V2, mutism, persistent hiccup
Anti-Yo rhombenceh- halitis
Shingo Mitraki et al. [31] Japan
13
M, 29
Consciousness disturbance
Drowsy, disoriented
pneumonia
Hideki Shibuya et al. [10] Japan
14
M, 30
Fever, consciousness disturbance
Glasgrow coma scale: E4V1M6
Mycoplasma- pneumoniae
Balasubramanyam Shankar et al. [32] India
15
F, 28
Fever, vomiting, paresthesia
Drowsy, neck rigidity, up going plantar reflex
NQ
Soon Young Ko et al. [33] Korea
16
M, 30
Fever, alalia
dysarthra
Nonfulminant hepatitis A
Makoto Hibino et al. [34] Japan
17
F, 24
Fever, diarrhea, abdominal pain, weakness of right upper extremity
Right-side hemiparesis, hemianesthesia, Chaddock (+)
adenovirus
Yuji Tomizawa et al. [11] Japan
18
M, 49
Fever, gait difficulty
Wide-based gait, fine postural tremors, mildly exaggerate deep tendon reflexes
Legionella pneumophila- serogroup 2
Robert M et al. [35] America
19
M, 41
Fever, headache, delirium, consciousness disturbance, tremor, gait instability, paresthesias, UT
Slow thought, mild difficulty finding words, intention tremor of the left arm, dysmetria of lower extremities, broad-based gait
ipilimumba
Jing Jing Pan et al. [36] China
20
F, 18
Fever
(−)
NQ
21
M, 26
Fever, acute UT
Nuchal rigidity (+)
NQ
22
F, 23
Fever, headache, disturbance of consciousness
Kerning (+)
C-section
23
M, 21
Fever, headache, acute UT, intestinal obstruction
Kerning (+)
NQ
Shuo Zhang et al. [37] China
24
F, 26
Headache, fever, seizure, somnolence
Somnolence
Mycoplasm-a
25
F, 34
Dizziness, fever, somnolence
Somnolence
Mumps virus
26
M,25
Headache, fever, cognitive impairment, behavioral disorders, confusion
Cognitive impairment, behavioral disorders, confusion
Herpes simplex virus
Eylem Degirmenci et al. [38] Turkey
27
M, 27
Headache, apathy, nausea, vomiting
Bilateral papilledema, mildly altered mental status
NQ
Naila Alakbarvova et al. [39] Turkey
28
M, 46
Headache, vomiting, nausea, diarrea, abdominal pain, generalized tonic-clonic seizure
Confusing with time disorientation
Amanita phalloides intoxication
Matthias Gawlitza et al. [40] Germany
29
F, 28
disorientated
Disorientated, confusion
Hemolytic uremic syndrome
M male, F female, UT urinary retention, NS no statement, NQ no required, VZV varicella zoster virus
Table 2
Auxiliary examination and treatment of 29 adult-onset MERS cases
Case no.
Initial examination
Treatment
WBC (109/L)
CRP (g/L)
Serum sodium (mmol/L)
CSF WBC (106/L)
MRI
EEG
1
10.99
9.41
131.8 (hyponatremia)
97
SCC
NE
mannitol, low dose methylprednisolone, ACV, anti-tuberculosis
2
NS
NS
NS
500
SCC
Slow BA
ACV, antibiotics
3
NS
NS
NS
17
SCC
Slow BA and spikes
PB, PSL
4
NS
NS
NS
Normal
SCC
Slow BA
ACV, PHT, PSL
5
NS
NS
NS
NE
SCC
NE
ACV
6
NS
NS
NS
Normal
SCC
Slow BA
ACV, antibiotics, PSL
7
18.8
17.0
NS
253
Entire CC and peripheral WM
NS
antibiotics
8
normal
normal
normal
normal
SCC and frontal WM
NS
No specific therapy
9
normal
normal
normal
408
SCC
normal
Ceftriaxone, ACV, ampicillin, catheterization
10
normal
normal
normal
normal
SCC, WM
NS
Methylprednisolone pulse, PSL, catheterization
11
NS
normal
132 (hyponatremia)
33
SCC
NS
Ceftriaxone, ACV, symptomatic therapy of headache and fever
12
NS
normal
133 (hyponatremia)
6
SCC, frontoparie-tal WM, putamina, thalami
Diffuse slowing wave
Antiepileptic treatment, methylprednisolone pulse, immunoglobulin treatment
13
elevated
elevated
NS
normal
Entire CC
NS
methylprednisolone pulse, immunoglobulin treatment
14
NS
NS
NS
NS
SCC
NS
Levofloxacin
15
NS
NS
NS
60
SCC, bilateral WM
Slow activity, frontal sharp wave
Empirical corticosteroids and ACV
16
3.48
NS
138
NS
SCC
abnormal
hemodialysis
17
normal
12.21
normal
NE
SCC
NS
No specific therapy
18
elevated
22.9
130
3
SCC
NS
Antibiotics
19
normal
normal
normal
128
SCC
NS
oral PSL and methylprednisolone pulse
20
6.08
normal
137.0
90
SCC
abnormal
methylprednisolone pulse, oral PSL
21
7.10
normal
130.2
100
SCC, insula, caudate nucleus
abnormal
Oral methylprednisolone and PSL
22
11.20
normal
138.6
12
SCC
abnormal
Oral methylprednisolone and PSL
23
8.20
normal
126.5
80
SCC
abnormal
Oral PSL
24
NS
NS
NS
3
SCC
Occipital slow waves
Mannitol, diazepam, macrolides antibiotics and moxifloxacin
25
NS
NS
NS
7
SCC
Occipital slow waves
Interferon, ribavirin
26
NS
NS
NS
112
SCC
Occipital slow waves
Ganciclovir, mannitol, antibiotics
27
normal
normal
normal
150
SCC
NS
Acetazolamide, antibiotics, oseltamivir
28
17.8
NQ
normal
normal
SCC
NS
Risperidone, clozapine, venlafaxine and diazepam, antipsychotic and intoxication treatment
29
NS
NS
NS
NS
SCC
NS
eculizumab
WBC white blood cell, CRP C-reactive protein, CSF cerebrospinal fluid, EEG electroencephalography, NE no examined, NS no statement, BA basic activity, ACV acyclovir, PB Phenobarbital, PSL prednisolone, PHT phenytoin, WM white matters
Of the 29 adult-onset MERS patients, 11 were from Japan, 8 from China, 3 from Turkey, 2 from Germany, 2 from Korea, 1 from France, 1 from India and 1 from America. From a geographical point of view, 86.2% of the countries were in Asia (25/29), especially in Japan (11/29).
The age of onset varied between 18 and 59 years old, with an average of 31. Twelve patients were females (41.38%) with a 12:17 female-to-male ratio. Fifteen patients had identified causes, including 5 virus infections, 3 pneumoniae, and 1 mycoplasma infection. One patient developed MERS due to Amanita phalloides toxication, one because of tick-bites. One patient had emotional and behavioral changes presenting with auditory hallucinations within 10 days after C-section.
Fever had preceded or simultaneously presented with neurologic symptoms in 24 patients. Twelve patients complained of headache while having MERS, and disturbance of consciousness was observed in 15 cases. Seizure occurred in 4 cases, and acute urinary retention in 6 patients. 75.9% of the patients (22/29) had an isolated lesion in the splenium of the corpus callosum. Six patients had lesions in both splenium and extracallosal. One patient had lesions in the entire corpus callosum. Lumbar punctures were performed in 23 patients, 15 of which had elevated CSF WBCs. Sixteen patients had their serum sodium reported, 6 of which had decreased levels. EEG was performed in 23 patients, 14 of which were abnormal.
The patients were treated with antiviral therapy, antibiotics, corticosteroids, IVIG, intravenous osmotic diuretic and isotonic fluid. Thirteen patients received corticosteroids therapy, 5 of which received a methylprednisolone pulse therapy. No case resulted in neurological sequelae.

Discussion

We reported a previously healthy 37-year-old man who suffered MERS associated with acute urinary retention. A lesion in the SCC resulting in acute urinary retention has rarely been reported. We considered acute disseminated encephalomyelitis (ADEM) being the main differential diagnosis. In comparison with the lesions in MERS which show no contrast enhancement and usually disappear quickly [1], the corpus callosum lesions in ADEM are usually asymmetrical, contrast-enhancing, extend to the white matter and spinal cord [16], and resolve over weeks to months. Our patient’s cranial MRI showed an isolated abnormal signal in the SCC with no contrast enhancement. His spinal cord MRI showed no obvious abnormalities. The follow-up MRI scan revealed normalized findings within two weeks. So the patient was diagnosed as MERS instead of ADEM.
At first, a reversible isolated SCC lesion on MRI was diagnosed as MERS [1]. Recent studies suggested additional similar lesions in the cerebral white matter and anterior aspects of the corpus callosum in some encephalitis/encephalopathy patients should also been regarded as MERS (type 2 MERS) [4, 5]. Since the radiologic range of MERS had been expanded, patient no.7, 8, 10, 12, 15, 21 and 29 were included in the literature review.
Similar to child-onset MERS, most adult-onset MERS patients were also reported in Asia, including Japan, China and India. Interestingly, the majority cases were reported in recent five years. The phenomenon may be related to ethnics and social factors, as well as lack of diagnostic awareness and criteria before 2011. The common neurological manifestations of MERS in adult were headache and disturbance of consciousness. However, disturbance of consciousness and seizures were the most common neurological symptoms in children [15]. We suspect that it is related to children’s immature central nervous system and blood brain barrier.
The pathogenesis of MERS is still unknown. There are several hypotheses, including intramyelinic edema, axonal damage, hyponatemia, and oxidative stress [1, 17, 18]. High signal intensity on DWI and decreased ADC values of white matter have been observed in MERS. The possible explanation for this is intrmyelinic edema resulting from separation of myelin layers [19, 20] and local infiltration of inflammatory cells [1, 3]. In this review, we found that more than half (15/23) cases had elevated white cells in the CSF. A previous small sample study reported that patients with MERS has an elevated IL-6 and IL-10 levels in CSF, however, the sample is not enough for any conclusions to be drawn [17]. ADC may return to normal within a week if the intramyelinic edema or inflammatory infiltrate resolves quickly. Takanashi et al. [21] reported that most patients with MERS had mild hyponatremia with a mean serum sodium level (131.0 ± 4.1 mmol/L) lower than that of the healthy group. Our review revealed that 6/16 MERS patients had hyponatremia upon admission. All these indicate that hyponatremia might be a possible cause of MERS. Taken all together, MERS is a rare syndrome with unclear pathogenesis. None of the existing hypotheses explains why MERS specially involves the site splenium.
In any patients presenting with symptoms of encephalitis/encephalopathy who are found to have lesions in the white matter, ADEM should be included in the differentials [1, 4, 22, 23]. ADEM is a post-infectious inflammatory disorder which can present with seizures, focal neurological signs or altered mental status days to weeks after the presumed infections [24]. MRI with contrast shows various enhancements of the lesions in ADEM depending on the stages of the acuity [24]. Other differential diagnoses include posterior reversible encephalopathy syndrome (usually hypertension-related and has subcortical white matter lesion), multiple sclerosis (characteristic relapsing-remitting course), Marchiafava-Bignami disease (often seen in alcoholism), ischemia (usually irreversible and has vascular territory distributions), diffuse axonal injury (head trauma-related), lymphoma (positive contrast enhancement), and extrapontine myelinolysis (happens with electrolyte abnormality) [25].
Even though the evidence of methylprednisolone pulse therapy and IVIG’s efficacy on MERS is still lacking, they are recommended for patients with infectious encephalopathy regardless of the pathogen or clinicl-radiological syndromes [26]. In this review, only five MERS patients were treated with methylprednisolone pulse therapy and two with IVIG treatment. However, all patients without methylprednisolone pulse therapy or IVIG recovered clinically completely, which suggests that those treatments may not be necessary.

Conclusion

In conclusion, we reported a case of an adult-onset MERS with acute urinary retention. Taken together with the previously reported cases, we suggest that MERS in adults is an entity with a broad clinico-radiological spectrum and the prognosis is good. From a geographical point of view, most adult-onset MERS patients were also reported in Asia. The common neurological manifestations were headache and disturbance of consciousness. There are similar characteristics between MERS in adults and children, also some differences.

Acknowledgment

None.

Funding

This work is supported by National Natural Science Foundation of China (Grant No. 81271309) and Beijing Municipal Administration of Hospitals’ Youth Programme (QML20150303).

Availability of data and materials

The datasets supporting the conclusions of this article are included within the article.

Authors’ contributions

JLY provided the adult-onset MERS case. WLH conceived and designed the experiments. SNY performed the literature search and drafted the manuscript. SKW performed the studies selection process. WQ and LY collected data from the selected articles. All authors have read and approved the final manuscript to be published.

Competing interests

The authors declare that they have no competing interests.

Consent for publication

The patient agreed his medical records, images to be published.

Ethics approval and consent to participate

This study has been approved by the Medical Ethical Research Committee of Beijing Chaoyang Hospital Affiliated to Capital Medical University. The patient gave consent to participate in this study.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://​creativecommons.​org/​licenses/​by/​4.​0/​), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://​creativecommons.​org/​publicdomain/​zero/​1.​0/​) applies to the data made available in this article, unless otherwise stated.
Literatur
Über diesen Artikel

Weitere Artikel der Ausgabe 1/2017

BMC Neurology 1/2017 Zur Ausgabe

Neu in den Fachgebieten Neurologie und Psychiatrie

Meistgelesene Bücher in der Neurologie & Psychiatrie

  • 2016 | Buch

    Neurologie

    Das Lehrbuch vermittelt Ihnen das gesamte Neurologie-Prüfungswissen für Ihr Medizinstudium und bereitet auch junge Assistenzärzte durch detailliertes Fachwissen optimal auf die Praxis vor. Die komplett überarbeitete Auflage enthält sechs neue, interdisziplinäre Kapitel.

    Herausgeber:
    Werner Hacke
  • 2016 | Buch

    Komplikationen in der Neurologie

    Das Buch schildert Ereignisse im Rahmen der Neuromedizin, die während der Diagnostik und Therapie neurologischer Erkrankungen und Symptome auftreten können. Die Fallbeispiele sensibilisieren Sie für mögliche Risikofaktoren, um das Auftreten solcher Komplikationen zu vermeiden.

    Herausgeber:
    Frank Block
  • 2017 | Buch

    Facharztwissen Psychiatrie, Psychosomatik und Psychotherapie

    Leitsymptome, Untersuchungsmethoden, Krankheitsbilder, Notfälle & Co. – mit der Neuauflage des "Facharztwissens" sind Sie auf die Facharztprüfung in Psychiatrie und Psychotherapie optimal vorbereitet. In dieser 2. Auflage sind die Kapitel zu psychosomatischen Störungen deutlich ausgebaut.

    Herausgeber:
    Prof. Dr. Dr. Frank Schneider
  • 2019 | Buch

    Kompendium der Psychotherapie

    Für Ärzte und Psychologen

    Dieses Werk wendet sich an Ärzte und Psychologen, die an psychiatrischen und psychosomatischen Kliniken oder an Psychotherapeutischen Ausbildungsinstituten arbeiten und in den vorhandenen Lehrbüchern der Psychotherapie den Brückenschlag zur …

    Herausgeber:
    Tilo Kircher