acute necrotizing encephalopathy

Central
nervous system complications associated with SARS-CoV-2 infection: integrative concepts of pathophysiology and case reports. Para-infectious autoimmunity. a Acute necrotizing encephalopathy (ANE). A 23-year-old SARS-CoV-2-positive female presented mainly with encephalopathy progressed to catatonia. C-reactive protein (CRP) was 72.3 mg/dl. CSF analysis was completely normal. Coronal (1) and axial (2) fluid-attenuated inversion recovery (FLAIR)/T2-weighted (T2W) MR images reveal signal hyperintensities of the ventromedial thalami and hippocampi. DWI (3) and ADC (4) images show slightly increased signal intensity on DWI but without low signal intensity on ADC to suggest diffusion restriction. Bilateral thalamic involvement is highly characteristic for ANE. Her neurological condition improved substantially following immune therapies that included intravenous immunoglobulin, intravenous pulse methylprednisolone, and rituximab. b Acute disseminated encephalomyelitis (ADEM). A 56-year-old SARS-COV-2 positive female admitted for diarrhea and hypoxemic respiratory symptoms that progressed to ARDS necessitating intubation. Notable laboratory findings were CRP of 31 mg/dl (reference range 0.00–0.40), ferritin of 799 ng/ml (reference range 15–150 ng/ml), D-Dimer of 362 ng/ml (reference range < 230 ng/ml), and IL-6 of 42 (reference range less < 5 pg/ml). Neurological examination was notable for severe encephalopathy and severe quadriplegia. Axial FlAIR MR images (1, 2, 3) demonstrate multiple periventricular white matter hyperintensity lesions, without corpus callosal involvement. There is no enhancement or restricted diffusion on DWI (4, 5, 6). These findings are consistent with acute disseminated encephalomyelitis. Patient received a 5-day course of intravenous pulse methylprednisolone (1000 mg/day) and tocilizumab 750 mg (8 mg/kg) intravenously. She improved substantially to the point of becoming fully awake and alert with 4/5 power of upper extremities and 3–4/5 power of lower extremities. Patient was discharged to an acute rehabilitation facility and then went home showing a steady neurological improvement
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Acute
hemorrhagic leukoencephalitis • Acute hemorrhagic leukoencephalitis - Ganzer Fall bei Radiopaedia
Dixon A, Acute hemorrhagic leukoencephalitis. Case study, Radiopaedia.org (Accessed on 08 Dec 2022) https://doi.org/10.53347/rID-14076 • CC by-nc-sa 3.0 (modified)
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Acute necrotizing encephalopathy, also referred as acute necrotizing encephalopathy of childhood, is a rare type of encephalopathy characterized by multiple bilateral brain lesions, mainly involving the thalami, but also the putamina, internal and external capsules, cerebellar white matter, and the brainstem tegmentum.

Epidemiology

Acute necrotizing encephalitis is a rare condition. From the first case described in 1995, many cases have been reported in Asia as well as many Western countries. Most cases are sporadic; however, a few cases of recurrent and/or familial episodes have been reported suggesting an inherited pattern.

Although the initial publications were in the pediatric population, multiple further reports showed the condition to also occur in adulthood.

Clinical features

Clinically, it is characterized by acute encephalopathy, with dramatic neurological deficits/symptoms. A viral etiology has been proposed in some cases; viral prodrome hence may precede the neurological deficits.

Pathology

The etiology and the pathogenesis of acute necrotizing encephalitis are only partially clear. Usually, it develops secondary to viral infections, including influenza A and influenza B, parainfluenza, varicella, and enterovirus. A recent case report, in the setting of the COVID-19 pandemic, has also implicated the virus SARS-CoV-2 as a possible trigger .

Pathologically, the lesions show edema, hemorrhage and necrosis. Acute necrotizing encephalopathy is characterized by the lack of inflammatory cells in affected brain parenchyma in comparison to the more common entities of acute disseminated encephalomyelitis and acute hemorrhagic encephalitis .

Radiographic features

CT

On CT, the corresponding thalamic, putamina, cerebral, cerebellar and brainstem abnormalities are hypodense.

Intracranial hemorrhage and cavitation may also be seen, both of which are associated with a worse prognosis.

MRI

In most cases of acute necrotizing encephalitis of childhood, there is bilateral symmetrical thalamic involvement. Abnormal signals on MRI are hypointense on T1 and hyperintense on T2. Restricted diffusion of the involved regions can be seen.  These findings can be quite extensive. Hemorrhage, cavitation, and post-contrast enhancement are also seen.

Treatment and prognosis

Acute necrotizing encephalitis of childhood carries a very poor prognosis; the mortality rate is near 70%. Treatment is mainly supportive, as the precise etiology remains unknown.

Differential diagnosis

If characteristic symmetric imaging findings are present, the differential diagnosis is limited. Lactic acidosis is not a classic finding of ANEC. Otherwise, the differential diagnoses include:

Clinically, acute necrotizing encephalitis of childhood may be differentiated from ADEM by an early onset of encephalitic features just after the prodromal illness while in ADEM, they may take 1 to 2 weeks to develop.

Siehe auch:
Assoziationen und Differentialdiagnosen zu akute hämorrhagische Leukoenzephalitis:
Leigh-Syndrom
 
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