99Journal of The Association of Physicians of India ■ Vol. 64 ■ August 2016

Dengue EncephalitisJasmine Porwal1, Ajay Chauhan2

De n g u e e n c e p h a l i t i s a s a manifestat ion of dengue is a

rare entity, the incidence being about 4-5% only. Dengue encephalitis can present with different manifestations, the commonest being alteration of consciousness seen in 52.3% cases.

where he was admitted as a case of dengue with left hemiplegia. There was no history of bleeding from any site. He was conscious, cooperative, well oriented in time, place and person. BP - 120/80 mm Hg, temperature- 100° F, pulse -90 beats /min.

On nervous system examination -power was 0/5 in both left upper and lower limbs and 5/5 in right upper and lower limbs. Left plantar showed absent and right plantar showed flexor response. B/L pupils had normal size with normal reaction to l ight and no cranial nerve deficit. There were no meningeal signs or any sensory loss. Gait and coordination could not be assessed. Other systems had no significant findings. At our centre median platelet count was 1.5- 1.9 lacs/cumm and IgM for dengue was positive.

CSF was done showed an albumin-cytological dissociation. Cytology- no cells and biochemistry - sugar 69 mg/dl, protein 105 mg/dl. Malaria card test was negative. Other viral markers and rickettsial serology was negative.

MRI (Figure 1) brain was suggestive of patchy discrete and confluent T2W/FLAIR hyperintensities seen involving t h e p e r i ve n t r i c u l a r , s u b c o r t i c a l and deep white matter, B/L fronto-parietal region, B/L thalami and B/L cerebellar hemispheres. There was patchy restriction involving the B/L frontal region and B/L cerebel lar hemispheres. Patchy areas of blooming (likely haemorrhage) involving right centrum semiovale and B/L cerebellar h e m i s p h e r e s wa s a l s o r e p o r t e d . These findings raised a possibility of haemorrhagic encephalitis was given.

The patient was treated on the lines of dengue with paracetamol and i.v. fluids only. There was reduction in spikes of fever with a sense of well-being and improvement in power. On the 5th day after admission-His power: Left LL/ Left UL = 4/5 and 2/5.

On the 12th day after admission,

Abstract Dengue infection accompanied by unusual complications and manifestations has been described before. Here we report a case of dengue encephalitis who was IgM positive for dengue serology and had presented to us with only motor weakness after an acute febrile episode. Dengue presenting as encephalitis is in itself a very rare feature and that too, pure motor weakness has hardly ever been reported before.

Introduction

1Post Graduate, Department of Medicine, 2Associate Professor, Department of Medicine, Postgraduate Institute of Medical Education and Research, Dr. Ram Manohar Lohia Hospital, New DelhiReceived: 28.12.2015; Revised: 20.04.2016; Accepted: 26.04.2016

Fig. 1: Patchy discrete and confluent T2W/FLAIR hyperintensities (arrows) involving b/l cerebellar hemispheres, subcortical and deep white matter of b/l fronto-parietal region

Others inc lude meningi t is (34%), seizures (11.2%), acute flaccid paralysis in 4% cases, myositis in 4% cases. Our patient was a case of dengue encephal i t is with only lef t motor hemiplegia with no sensory or cranial nerve involvement. The purpose of writing this was to sensitize ourselves that out of the myriad presentations, dengue encephalitis can also present with only motor symptoms without any other neurological manifestations.

Case

A 38 years old previously healthy male presented to us with fever (100-102° F) since 7 days and weakness of left arm and leg since 2 days. His fever used to get relieved with paracetamol. Five days after the onset of fever he had 2-3 episodes of vomiting followed by loss of consciousness which lasted for about 20 to 30 minutes. This was associated with clenching of teeth and tightening of limbs. On regaining consciousness the patient noted left sided weakness. Urgent CT brain raised suspicious of an inflammatory granuloma in right high parietal region with edema. His platelet count was 59000 cumm with NS1 positive for dengue by ELISA. Other blood parameters were within normal limits. There was no history of petechiae or bleeding from any site and his vital parameters were stable. Therefore, he came to our hospital

100 Journal of The Association of Physicians of India ■ Vol. 64 ■ August 2016

patient was discharged. He was afebrile and power was the same as above. About 10 days after discharge when the patient followed up in the OPD, he had completely recovered and had regained his full power in left upper and lower limb.

Discussion

Dengue virus belongs to family Flavivirdae, which also includes yellow fever, Japanese encephalitis, West Nile virus.1 Usually it is considered as a non- neurotropic virus, though nowadays neuroinvasion has been reported. Dengue encephalitis is classified as severe dengue in the latest WHO classification 2009.

T h e p a t h o g e n e s i s o f d e n g u e encephalitis has been postulated to be the transient compromise in the integrity of the blood brain barrier with infiltration of dengue virus infected macrophages in CNS. Vasculitis with resultant fluid extravasation also has a role in its manifestations.Diagnosis

The gold standard for diagnosis of any viral encephalitis is virus isolation in cell culture (Class 1a). Since newer methods like polymerase chain reaction (PCR) assay are quicker, more widely available and they are more often used. Class 1b evidence suggests intrathecal antibody production to a specific virus.2

This said, the published literature for dengue encephalitis in itself, has shown very low yield of evidence for dengue in CSF.3-5 In Vietnam, Solomon et al.3

made a clinical diagnosis of dengue encephalitis in nine encephalopathic

patients. All had dengue confirmed in the serum. However, virus and/or antibody were found in the CSF of only two of these patients. Also, seven patients showed no classic features of dengue infection, leading the authors to suggest that dengue be considered in all encephalitic patients in endemic areas, regardless of the presence or absence of classical features.

Back home, a s tudy conducted in SGPGI Lucknow, 1 inc luded 16 confirmed dengue patients by serology with encephalopathy. Out of these 6 patients had a metabolic and hypoxic cause, 2 had intracranial haemorrhage as the cause while 8 patients had no cause. Out of these 8 cases, only 3 patients had CSF IgM ELISA for dengue positive.

In our patient also, CSF anti dengue antibody was negative but his IgM serology was positive.Brain Imaging

In our pat ient , MRI Brain also helped us in confirming the diagnosis of dengue encephali t is . Although there are no pathognomonic findings of the same, but general f indings consistent with viral encephali t is include cerebral edema, white matter changes, and (later) necrosis and brain atrophy. Infarction or hemorrhage may also be visible. Breakdown of the blood-brain barrier may be visualized as signal enhancement on MRI with gadolinium contrast. MRI lesions in the hippocampi, temporal lobes, pons, and spinal cord can also be seen.6

Prognosis

Reported mortality and morbidity

due to dengue encephalitis itself is low with most survivors recovering fully. In the studies mentioned above3-5 all patients recovered completely with residual symptoms in only 3 patients in one study.

Neurologic manifestations in dengue are increasingly being recognized but remain relatively poorly understood. T h o u g h t h e c o m m o n p r e s e n t i n g features of dengue encephalitis are fever, headache, reduced consciousness a n d s e i z u r e s , o t h e r n e u r o l o g i c manifestations may also be evident and c lass ica l fea tures o f dengue may not always be present. Virus or antibody is reliably isolated from the serum although CSF samples are often negative. Thus dengue infection should be considered in cases of encephalitis in the tropics in which the disease is endemic as echoed by Solomon et al3 and Hommel et al.

References1. Misra UK, Kalita J. Spectrum of neurological manifestations

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2. Steiner I et al. Viral encephalitis: a review of diagnostic methods and guidelines for management. European journal of Neurology 2005; 12:331-343.

3. Solomon T, Dung NM, Vaughn DW et al. Neurological manifestations of dengue infection. Lancet 2000; 355:1053-9. 

4. Kankirawatana P, Chokephaibulkit K, Puthavathana P et al. Dengue infection presenting with central nervous system manifestation. J Child Neurol 2000; 15:544-7.

5. Kularatne SA, Pathirage MM, Gunasena S. A case series of dengue fever with altered consciousness and electroencephalogram changes in Sri Lanka. Trans R Soc Trop Med Hyg 2008; 102:1053-4.

6. Muzaffar J, Venkata Krishnan P, Gupta N, Kar P. Dengue encephalitis: why we need to identify this entity in a dengue-prone region. Singapore Med J 2006; 47:975-7.