Acute Necrotizing Encephalopathy of Childhood (ANEC) in a Patient with Dengue and Leptospirosis

Sir, ANEC is an acute encephalopathy that has a distinctive clinicoradiological presentation and a fulminant clinical course.[1] This is by far the first case reported in the literature, where dual infection with Dengue (viral illness) and Leptospirosis (bacterial infection) was implicated in the causation of this rare entity. A 14-year-old boy presented to the emergency room (ER) with a high-grade fever, pain abdomen, vomiting and loose stools of three days duration, and multiple episodes of generalized tonic–clonic seizures. He was obtunded on a mechanical ventilator with a Glasgow coma scale (GCS) of 4, had icterus, and the plantars were extensors. A provisional diagnosis of acute febrile illness with encephalitis was made. His laboratories showed anemia, thrombocytopenia, and transaminitis. Dengue serology was positive for NS1 and IgM antibodies and Leptospira serology was positive for IgM antibodies. MRI brain features were consistent with necrotizing encephalopathy Figure 1]. EEG showed delta range slowing. We made a diagnosis of Acute Necrotizing Encephalopathy of Childhood (ANEC) associated with Dengue and Leptospirosis. He was started on antibiotics, Oseltamivir, and intravenous Methyl Prednisolone. Despite the best possible efforts, patient succumbed to the illness.Figure 1: Acute necrotizing encephalopathy of childhood (ANEC). Diffusion weighted image (DWI) (a) showing symmetrical restricted diffusion in bilateral thalami. Apparent diffusion coefficient (ADC) (b) image of thalamocapsular region reveals tricolor pattern of thalamus with inner hyper intensity (represented by ‘*’) corresponding to area of hemorrhagic necrosis; central restricted diffusion (single arrow) corresponding to congestion and acute swelling of oligodendrocytes and peripheral hyper intense signal (double arrow) representing extravasated fluid. FLAIR (c), T2 sagittal (d), T2 FS coronal (e and f) reveal bilaterally symmetrical areas of T2 prolongation in the thalami, hippocampi, brainstem tegmentum and temporal, parietal, frontal and high fronto parietal subcortical and cerebellar white matter. Susceptibility weighted imaging (SWI) Mag (g-i) images reveal hemorrhagic areas within the white matter hyper intensities and thalamiVarious infectious agents have been implicated among which the influenza virus and HHV-6 are the most common.[1] There have been limited case reports of ANEC in association with Dengue infection.[2] IL-6 and TNF-α are the most important inflammatory mediators which are neurotoxic and disrupt the blood–brain barrier. “Cytokine storm” is a prevalent hypothesis.[3] MRI Brain has a characteristic appearance with symmetrical, multifocal lesions that invariably involve the thalami.[4] Hemorrhage occurs predominantly in the central portion of the involved deep gray matter.[4] Lesions in the brain are edematous and combined with mass effect.[4] Follow-up MRI may have atrophy, hemosiderin deposition, and white matter cysts in the involved regions.[4] ANEC is a rare fulminant encephalitis with a fatal course. A high index of suspicion and characteristic MRI features clinch the diagnosis. Dengue and many other bacterial infections also may herald this abysmal entity. Early treatment with pulse steroids and high dose of antivirals may improve the prognosis. To the best of our knowledge, this is the first case report of ANEC associated with both viral (Dengue) and bacterial (Leptospira) infection. Is it a mere coincidence or a clear case of convergence remain elusive? Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.