|Year : 2015 | Volume
| Issue : 2 | Page : 169-171
A case of acute disseminated encephalomyelitis following dengue infection
Department of General Medicine, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
|Date of Web Publication||16-Mar-2015|
Doctor's Hostel, Institute of Post-Graduate Medical Education and Research, AJC Bose Road, Kolkata - 700 020, West Bengal
Source of Support: None, Conflict of Interest: None
Neurological manifestations after dengue are not very common and acute disseminated encephalomyelitis (ADEM) following dengue infections is still more infrequent. Few cases have been documented in literature. Characteristic clinical presentation and typical lesions of ADEM on magnetic resonance imaging (MRI) brain along with serologic positivity for dengue usually confirms the diagnosis. The author reports a case of ADEM which developed as a neurological complication of dengue.
Keywords: Acute disseminated encephalomyelitis, dengue, magnetic resonance imaging
|How to cite this article:|
Chakrabarti S. A case of acute disseminated encephalomyelitis following dengue infection. CHRISMED J Health Res 2015;2:169-71
|How to cite this URL:|
Chakrabarti S. A case of acute disseminated encephalomyelitis following dengue infection. CHRISMED J Health Res [serial online] 2015 [cited 2019 Oct 21];2:169-71. Available from: http://www.cjhr.org/text.asp?2015/2/2/169/153268
| Introduction|| |
Dengue infection is caused by aflavivirus, and the nervous system involvement including acute disseminated encephalomyelitis (ADEM) is seen with serotypes 2 and 3. ADEM produces multiple inflammatory lesions in the brain and spinal cord, particularly in the white matter. Usually these are found in the subcortical white matter and cortical grey-white junction of both cerebral hemispheres, cerebellum, brainstem, and spinal cord; however, periventricular white matter and grey matter of the cortex, thalami, and basal ganglia may also be involved. ,
| Case Report|| |
A 29-year-old male hailing from rural parts of West Bengal and grocer by occupation was rushed to the emergency in a drowsy state. According to his family members, he had fever for last 6 days and convulsions for last 1 day. Fever was high grade, continuous in nature with chills and rigor, and responded partially to medications. He also had complained of severe headache and retro-orbital pain and arthralgia. He became unconscious and developed generalized tonic-clonic seizures several times in last 24 h. Convulsions were associated with vomiting. There was no history of recent vaccination or history suggestive of poisoning or recent travel. On examination, he was restless, irritable, and febrile with temperature of 103F, pulse 110 bpm, and blood pressure (BP) 96/60 mmHg. He was mildly plethoric. Generalized erythematous macular rash on skin was noted which blanched on pressure. Tourniquet test was positive. Neurological examination revealed that patient had Glasgow coma scale (GCS) score 9/15. Pupils were mid-dilated and equal in size with sluggish reaction to light. There was no papilledema or retinal hemorrhage on fundoscopy. Signs of meningeal irritation were absent; cranial nerves, motor and sensory system could not be examined properly as the patient could not follow vocal commands. Rest of the clinical examination was noncontributory except mild epigastric tenderness. Seizures were controlled with intravenous lorazepam and phenytoin. Our differential diagnoses were encephalitis or ADEM or cerebral malaria; accordingly, patient was treated empirically with intravenous (IV) ceftriaxone, acyclovir, artesunate, and dexamethasone prior to results of laboratory tests.
Complete blood count revealed hemoglobin (Hb) - 11.6 g/dl, white blood cell (WBC) -3,700/mm 3 , platelet-90,000/mm 3 ; hematocrit (Hct)-46.5%, and erythrocyte sedimentation rate (ESR)- 27mm/first h. Liver and renal function tests were normal and electrolyte study showed mild hyponatremia (Na + - 127mEq/l; N 135-145 mEq/l). Urinalysis showed no abnormality. Blood culture showed no growth. Cerebral spinal fluid (CSF) study showed normal sugar and cell count with raised protein (98mg/dl; N: 20-40 mg/dl), while Gram stain and Ziehl-Neelsen (Z-N) stain revealedno organism. Chest X-ray and abdominal ultrasound study were within normal limits. Dual antigen test for malaria was found to be negative, immunoglobulin (Ig) M anti-dengue came out to be positive, while IgG anti-dengue was negative. Serology for viral hepatitis, Japanese encephalitis, Epstein Barr virus, and herpes simplex virus (HSV)-1 was also negative. Magnetic resonance imaging (MRI) of brain revealed T1hypointensities and T2/T2-fluid attenuated inversion recovery (FLAIR) hyperintense signal changes in both thalamic, parietal, and occipital white matter, brainstem and corpus callosum [Figure 1],[Figure 2]a nd [Figure 3] suggestive of ADEM. Contrast enhancement was absent, further supporting demyelinating pathology. Dengue virus could not be isolated from the CSF ruling out presence of dengue encephalitis. After confirmation of ADEM on MRI, dexamethasone, antiviral, antimalarials were stopped, and injectable methylprednisolone for 3 days was administered followed by tapering dose of oral prednisolone for further 8 weeks. A final diagnosis of ADEM following dengue fever was made. The patient gradually improved on treatment and was discharged in stable condition with slight residual cerebellar ataxia.
|Figure 1: Multiple diffuse T2 FLAIR hyperintensities in parietal lobe, occipital lobein MRI sagittal view suggestive of ADEM. ADEM = Acute disseminated encephalomyelitis, MRI = magnetic resonance imaging, FLAIR = fl uid attenuated inversion recovery|
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|Figure 2: Multiple diffuse T2 FLAIR hyperintensities in brainstem, corpus callosumin MRI sagittal view suggestive of ADEM|
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|Figure 3: Multiple diffuseT2 FLAIR hyperintensities in parietal lobe, basal ganglia, and splenium of corpus callosumin MRI horizontal view suggestive of ADEM|
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| Discussion|| |
ADEM is an immune-mediated disease of the brain. It usually occurs following a viral infection, but may appear after vaccination or bacterial or parasitic infection or even without a precipitating event. Most cases follow a nonspecific upper respiratory tract infection. Although it occurs in all ages, most reported cases are in children and adolescents with the average age around 5-8-years-old.  Viral infections known to induce ADEM include influenza virus, enterovirus, measles, mumps, rubella, varicella-zoster, coxsackie, Epstein-Barr, cytomegalovirus, HSV, hepatitis A, and rarely dengue; while bacterial infections include Borrelia burgdorferi, Mycoplasma pneumoniae, Leptospirapneumophila. 
The molecular mimicry is responsible for immunogenic injury. The favorable response to steroids suggests role of inflammation and immune-mediated injury in the pathogenesis of this acute demyelinating illness. It usually results from a transient autoimmune response towards myelin or other self-antigens possibly via molecular mimicry or by nonspecific activation of autoreactive clones. Peptides from microbial proteins with structural similarity with the host's self-peptides can activate T-lymphocytes which then infiltrate the central nervous system crossing the blood brain barrier, leading to inflammation and demyelination. 
ADEM has anabrupt onset and a monophasic course. Symptoms usually begin 1-3 weeks after the precipitating event-infection or vaccination. The index patient developed ADEM on the 8 th day after development of clinical manifestations of dengue. Major symptoms include fever, headache, drowsiness, seizures, and coma; all of which were noted in the index patient. Additional manifestations include paraparesis, cranial nerve palsies, hemiparesis, brainstem syndromes, optic neuritis, myelitis, and rarely myeloradiculopathy, extrapyramidal manifestations, etc., Therapy consists of use of high-dose steroids, plasma exchange, and intravenous immunoglobulin with usually favorable results and leaving little functional deficit.  However, recovery may be delayed and incomplete even after timely institution of treatment. The index patient was treated with high-dose methylprednisolone and recovered well with slight residual cerebellar ataxia.
Neurologic manifestations in dengue occur in upto 5% of cases. Denguecan affect any part of the nervous system and it may manifest as encephalopathy; encephalitis; Guillain-Barre syndrome (GBS), myelitis; meningitis; ADEM; stroke, both ischemic and and hemorrhagic; muscle dysfunction; and neuro-ophthalmic disorders. , The exact incidence of these individual complications is uncertain. The pathogenesis may involve:
(i) Direct neurotropic effect of the dengue virus, (ii) systemic effects of dengue infection, and (iii) immune-mediated (which includes ADEM).  ADEM following dengue infection is distinctly rare. 
Three distinct categories of disease can be classified using MRI criteria:
(i) Multifocal lesions in the white matter with or without basal ganglia involvement; (ii) single or multifocal lesions only in the grey matter; and (iii) localized lesions in the brain stem, basal ganglia, or cerebellum. Cranial MRI findings in our patient fall into the first category involving the white matter and left basal ganglia.  The index patient showed the first pattern. Demy elinating lesions with or without foci of hemorrhage on MRI are probably pathognomonic of ADEM following dengue infection. Although hemorrhagic lesions were not observed, typical distribution of demy elinating lesions in the background of dengue seropositivity and supportive clinical presentation convincingly establishes this case as ADEM following dengue infection. 
| Conclusion|| |
In countries like India where dengue is common, development of ADEM as its complication must be considered in appropriate clinical setting. With prompt recognition and timely institution of treatment, ADEM can resolve with little residual sequalae; but any delay in management usually leads to severe neurological neurodeficit and can even be life-threatening.
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[Figure 1], [Figure 2], [Figure 3]
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|[Pubmed] | [DOI]|