Acute necrotising encephalopathy of childhood (ANEC). Mizuguchi et al described ANEC in Japan in 1995.
1 Most cases are from East Asia but not limited to any particular race.
2 ANEC follows infection with influenza, Herpes Simplex Virus, Human Herpes Virus-6, Parainfluenza virus, Varicella Zoster Virus, reovirus, rotavirus, enterovirus, measles, coxsackie-A9 and mycoplasma.
3 ANEC occurs within days of fever and presents with convulsions and coma.
1 Acute manifestations are febrile seizures, movement disorder, frontal lobe encephalopathy and multiorgan failure.
2,3 Subacute manifestations are Guillain-Barre syndrome, transverse myelitis, acute disseminated encephalomyelitis, cerebellitis and myositis. Late manifestations are parkinsonism and encephalitis lethargica.
3 Patients of 2009 H1N1 influenza pandemic showed heightened neurological complications and ANEC compared to 2004–2008 seasonal influenza.
3 Cytokine storm following viral infection leads to systemic immune response causing multiorgan injury, brain cell apoptosis and cerebral edema from disruption of blood-brain barrier in ANEC.
2,3 RANBP2 genetic polymorphism is associated with recurrent episodes of ANEC with viral respiratory infections.
4 Central necrosis, surrounding cytotoxic oedema and peripheral vasogenic oedema forms pathological basis for MRI appearance.
3 T1W show hypointense lesions, T2W/FLAIR display corresponding mixed hyperintense signals with restricted diffusion on DWI and circular enhancement on contrast MRI.
2 Normal CSF and characteristic bilateral thalamic involvement with diffusion restriction help in making diagnosis.
5 Acute disseminated encephalomyelitis, neurovascular accidents, Reye’s syndrome, mitochondrial dysfunction and fulminant hepatitis are other differentials.
3,6 Outcomes range from full recovery (<10%), neurologic sequelae in survivors to fulminant progression in majority.
3 Li et al observed positive correlation between MRI findings and clinical outcome.
2 Observation of hemorrhage and local tissue loss on MRI predicts a poor prognosis.
2 Selective vulnerability of thalami seems to be determining factor.
6 Antivirals, immunoglobulin, plasmapheresis, antithrombin-III, and therapeutic hypothermia has been tried.
3 High dose steroids used in earlier stages determines the prognosis.
6 Follow-up imaging shows regression of lesions with residual cortical atrophy, cystic changes and haemosiderin deposition. Functional recovery following rehabilitation has been reported.
3
Given the potential for ANEC recurrence, monitoring of children with history of neurological complications following respiratory illness is indicated during influenza season with prompt testing and antiviral therapy.
4 Annual influenza vaccination is important for ANEC survivors and their household contacts.
4| References : |
- Mizuguchi M, Abe J, Mikkaichi K, Noma S, Yoshida K, Yamanaka T, Kamoshita S. Acute necrotising encephalopathy of childhood: a new syndrome presenting with multifocal, symmetric brain lesions. J Neurol Neurosurg Psychiatry. 1995;58:555-561.
- Li H, Sun C, Chi S, Wang Y, Wu L, Qin X. Use of MRI in the diagnosis and prognosis of acute necrotizing encephalopathy in a Chinese teenager. Medicine 2019;98:44.
- Yoganathan S, Sudhakar SV, James EJ, Thomas MM. Acute necrotising encephalopathy in a child with H1N1 influenza infection: a clinicoradiological diagnosis and follow-up. BMJ Case Rep. 2016 Jan 11;2016:bcr2015213429.
- Howard A, Uyeki TM, Fergie J. Influenza-Associated Acute Necrotizing Encephalopathy in Siblings. J Pediatric Infect Dis Soc. 2018;7: e172-177.
- Sharma M, Sood D, Chauhan NS, Negi P. Acute necrotizing encephalopathy of childhood. Neurol India. 2019;67:610‐611.
- Seo HE, Hwang SK, Choe BH, Cho MH, Park SP, Kwon S. Clinical spectrum and prognostic factors of acute necrotizing encephalopathy in children. J Korean Med Sci. 2010;25:449-453.
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