the dengue virus is a single - stranded rna virus of the flaviviridae family causing dengue fever and dengue hemorrhagic fever . dengue encephalopathy is usually secondary to multisystem derangement like shock , hepatitis , coagulopathy , and concurrent bacterial infection . dengue encephalitis is a different entity , which occurs due to direct neuronal infiltration by the dengue virus . we report a case of dengue shock syndrome with encephalitis , with peculiar mri findings . a 17-year - old girl presented with a history of high - grade fever and rigors for three days . she had two episodes of vomiting , generalized headache , and altered sensorium , lasting for 15 to 20 minutes , few hours prior to admission . there was no significant past medical history . on admission she was febrile , with a temperature of 101f , pulse of 132 / minute , blood pressure of 90 / 40 mmhg ( map-60 mmhg ) and cold extremities . on pulse she was pale , and skin rash , edema , icterus , and clubbing were absent . first dose of third generation cephalosporin was given empirically in view of the possibility of bacterial infection . investigations revealed hemoglobin ( hb ) of 14.5 g / dl , packed cell volume ( pcv ) of 45 , white blood cell count ( wbc ) of 7100 / cumm , with neutrophils 64% , lymphocytes 34% , and monocytes 2% . the platelet count was 1.35 lacs / cumm and esr was 48 mm at the end of one hour . u / l , sgpt-182u / l. serum albumin was 3.65 gm / dl , and inr was 2.0 . blood urea nitrogen was 39 gm / dl with creatinine of 1.4 mg / dl . there was evidence of metabolic acidosis with blood lactate 2.00 mmol / l on initial blood gas . no hypoxia or hypercapnia was seen ; x- ray chest and 2 d echocardiography were normal . ultrasonography ( usg ) showed evidence of bilateral minimal pleural effusion with mild ascites . the patient 's blood pressure and urine output improved after initial resuscitation with crystalloids . a few hours later , this young girl had an episode of generalized tonic - clonic seizure with unresponsiveness . she was intubated and ventilated in view of the poor level of consciousness after the seizure . it showed [ figure 1 ] extensive parenchymal hyperintense lesions in the bilateral cerebellar cortex , vermis of the cerebellum , entire pons and midbrain , bilateral medial temporal lobes , and both thalami , on t2 and fluid attenuated inversion recovery ( flair ) images . these lesions look hypointense on t1w images , hyperintense on flair images , and dark on the adc map . small foci of hemorrhage in the thalamic lesions looking hypointense , were seen on the t2 gre images . t 2 flair and t2-weighted images showing involvement of thalamus , pons , and cerebellum , with presence of hemorrhage on t2 and restricted diffusion on dwi cerebrospinal fluid ( csf ) analysis was done . igg / igm antibodies for dengue were positive in the serum as also on the dna polymerase chain reaction ( pcr ) for dengue . titers for hepatitis viruses were negative ( hav , hev , hbsag , hcv ) . serum procalcitonin was 0.3 ng / ml ( negative less than 0.5 ng / ml ) . her liver functions improved subsequently , and serum ammonia and electrolytes were within normal limits . she remained comatose even after correction of shock , hepatitis , metabolic acidosis , and coagulopathy . the mri brain findings were in favor of the possibility of direct extensive neuronal injury . although the mri brain findings were in favor of je , csf analysis was negative for je . therefore , the possibility of viral encephalitis due to dengue was strongly suspected . during the hospital course , she developed multiorgan dysfunction , shock , and acute respiratory distress syndrome ( ards ) . empirical antibiotics and antimalarials were continued till reports of the causative agent were obtained , and then withdrawn . table 2 shows her investigations over the next 10 days . in spite of all the treatment she continued to remain comatose , with hemodynamic compromise , and expired on the eleventh day after admission dengue virus infections are among the most common cause for hospital admissions in western maharashtra . it is estimated that 50 to 100 million infections and 25,000 fatalities occur worldwide every year . the world health organization ( who ) surveillance shows that the global incidence is rising . numerous neurological manifestations like transverse myelitis , myositis , and gullian - barre syndrome have been reported . dengue encephalopathy is a well - recognized and common entity , the incidence ranging from 0.5 to 6.2 % . the possible mechanisms are liver failure ( hepatic encephalopathy ) , cerebral hypoperfusion ( shock ) , cerebral edema ( vascular leak ) , deranged electrolytes , and intracranial bleeding due to thrombocytopenia or coagulopathy , which is secondary to hepatic failure . _ there are subsets of patients in whom the cause for neurological injury remains unclear even after excluding the above - mentioned indirect mechanisms . dengue is thought to be a non - neurotropic virus . however , there are reports of the demonstration of dengue virus and igm antigen in the cerebrospinal fluid ( csf ) of patients with encephalopathy . there are case reports by misra et al . , from india , and solomon et al . , from vietnam , 11 patients were seen with confirmed dengue infection , but no csf study was reported . solmon et al . , diagnosed dengue encephalitis in nine patients , but virus or antibody was found in the csf of only two cases . kularatne et al . , had a similar study in which they showed the association of dengue with encephalitis . on admission our patient had a history suggestive of encephalopathy with shock , coagulopathy , metabolic acidosis , and deranged liver functions . the mri findings noted in our case are most characteristic of je and not commonly seen with dengue fever . [ bilateral thalamic involvement with foci of hemorrhage , with involvement of temporal lobe and brain stem ] is very uncommon with dengue . this case is presented to highlight the possible extensive involvement of the brain by dengue virus . dengue is not classically a neurotropic virus , although there is recent evidence of direct neuronal injury . dengue encephalitis must be thought of in differentials of encephalopathy , in patients with dengue . in such cases , neuroimaging and csf analysis the virus or antibody can be isolated from the serum , but the csf samples may be negative . the dengue encephalitis is thought to be benign , but can be fatal at times . the role of an antiviral in such cases needs to be further defined because of the extensive parenchymal involvement and possible unfavorable outcome .