Brain magnetic resonance imaging of an adult case of acute necrotizing encephalopathy

Roles of Nucleoporin RanBP2/Nup358 in Acute Necrotizing Encephalopathy Type 1 (ANE1) and Viral Infection

Ran Binding Protein 2 (RanBP2 or Nucleoporin358) is one of the main components of the cytoplasmic filaments of the nuclear pore complex. Mutations in the RANBP2 gene are associated with acute necrotizing encephalopathy type 1 (ANE1), a rare condition where patients experience a sharp rise in cytokine production in response to viral infection and undergo hyperinflammation, seizures, coma, and a high rate of mortality. Despite this, it remains unclear howRanBP2 and its ANE1-associated mutations contribute to pathology. Mounting evidence has shown that RanBP2 interacts with distinct viruses to regulate viral infection. In addition, RanBP2 may regulate innate immune response pathways. This review summarizes recent advances in our understanding of how mutations in RANBP2 contribute to ANE1 and discusses how RanBP2 interacts with distinct viruses and affects viral infection. Recent findings indicate that RanBP2 might be an important therapeutic target, not only in the suppression of ANE1-driven cytokine storms, but also to combat hyperinflammation in response to viral infections.

Clinical and cytokine profile of adult acute necrotizing encephalopathy

Background

Acute necrotizing encephalopathy (ANE), a fulminant encephalopathy, is often found in childhood. It is still uncertain whether adult patients with ANE display clinical features different from patients with typical pediatric onset. Furthermore, alterations in neuroinflammatory factors in patients with ANE have not been well-characterized. Here, we present an adult patient with ANE, and review all reported adult ANE cases in the literature.

Methods

Serum levels of five cytokines were checked in an adult patient with ANE and compared with gender/age-matched controls. Literature search was performed with PubMed, using the term as “acute necrotizing encephalopathy” with the filter of adult 19 + years.

Results

A total of 13 adult patients were reviewed. Compared with pediatric patients, adult ANE patients had similar clinical symptoms, biochemical data, and neuroimage findings, whereas adult ANE were more female-biased (female:male, 9:4) with a worse prognosis. Elevated cytokine levels in the serum and/or CSF is found in both adult-onset and pediatric-onset ANE. We found significantly elevated serum levels of IL-6 (17.17 pg/mL; healthy control: 1.43 ± 1.22 pg/mL) and VCAM-1 (3033.92 ng/mL; healthy control: 589.71 ± 133.13 ng/mL), and decreased serum TGF-β1 level (14.78 ng/mL, healthy controls: 25.81 ± 6.97 ng/mL) in our patient.

Conclusions

Our findings clearly delineate the clinical features and further indicate the potential change in cytokine levels in adult patients with ANE, advancing our understanding of this rare disease.

Elderly-onset acute necrotizing encephalopathy mimicking severe heat stroke: a case report and review of the literature

Background

Acute necrotizing encephalopathy (ANE), known as influenza-associated encephalitis, typically affects children.

Case presentation

A 70-year-old woman was admitted to the hospital with altered consciousness, a high temperature, and severe hypotension. Computed tomography (CT) of the head showed no abnormalities; thus, a diagnosis of suspected severe heat stroke was made. On day 2, repeated head CT revealed bilateral symmetrical lesions to the thalamus, and a rapid influenza antigen test was positive. Based on the CT findings and the medical history of influenza, a differential diagnosis of ANE was made. Subsequently, brain edema spread across the whole brain, and the patient died on day 21.

Conclusion

In elderly patients, differentiating ANE from severe heat stroke in a high-temperature environment is difficult because of the similarities in clinical symptoms due to multiple organ failure.

Deep cerebral venous thrombosis mimicking influenza-associated acute necrotizing encephalopathy: a case report

Background

Acute necrotizing encephalopathy is one of the most devastating neurological complications of influenza virus infection. Acute necrotizing encephalopathy preferentially affects the thalamus bilaterally, as does deep cerebral venous thrombosis, which can lead to misdiagnosis.

Case presentation

A 52-year-old Japanese woman infected with seasonal influenza B virus presented to the emergency care unit in our hospital with progressive alteration of her level of consciousness. Bilateral thalamic lesions were demonstrated by magnetic resonance imaging, leading to a tentative diagnosis of acute necrotizing encephalopathy. However, she had deep cerebral venous thrombosis, and the presence of diminished signal and enlargement of deep cerebral veins on T2*-weighted imaging contributed to a revised diagnosis of deep cerebral venous thrombosis. Anticoagulant therapy was initiated, leading to her gradual recovery, with recanalization of the deep venous system and straight sinus.

Conclusions

To the best of our knowledge, these results represent the first report of deep cerebral venous thrombosis associated with influenza infection. It is clinically important to recognize that deep cerebral venous thrombosis, although rare, might be one of the neurological complications of influenza infection. In the presence of bilateral thalamic lesions in patients with influenza infection, deep cerebral venous thrombosis should be considered in addition to acute necrotizing encephalopathy. Delays in diagnosis and commencement of anticoagulant therapy can lead to unfavorable outcomes.

Acute necrotizing encephalopathy: an underrecognized clinicoradiologic disorder

Acute necrotizing encephalopathy (ANE) is a rare but distinctive type of acute encephalopathy with global distribution. Occurrence of ANE is usually preceded by a virus-associated febrile illness and ensued by rapid deterioration. However, the causal relationship between viral infections and ANE and the exact pathogenesis of ANE remain unclear; both environmental and host factors might be involved. Most cases of ANE are sporadic and nonrecurrent, namely, isolated or sporadic ANE; however, few cases are recurrent and with familial episodes. The recurrent and familial forms of ANE were found to be incompletely autosomal-dominant. Further the missense mutations in the gene encoding the nuclear pore protein Ran Binding Protein 2 (RANBP2) were identified. Although the clinical course and the prognosis of ANE are diverse, the hallmark of neuroradiologic manifestation of ANE is multifocal symmetric brain lesions which are demonstrated by computed tomography (CT) or magnetic resonance imaging (MRI). The treatment of ANE is still under investigation. We summarize the up-to-date knowledge on ANE, with emphasis on prompt diagnosis and better treatment of this rare but fatal disease.

The etiology of ring lesions on diffusion-weighted imaging

This study describes a series of cases and reviews the literature on cases of ring lesion on diffusion-weighted imaging to better appreciate the spectrum of disease associated with this neuroimaging finding. We retrospectively reviewed the MR studies of 15 patients with ring pattern lesions on diffusion-weighted imaging from an inpatient Neurology service of a tertiary care center seen over a ten-year period, and reviewed cases in the literature. Thirty-one cases, including 15 new patients, comprise the study group. Immunocompromised patients accounted for 38% of patients with ring lesions on diffusion-weighted imaging with cerebral aspergillosis in five patients, progressive multifocal leukoencephalopathy in three, primary CNS lymphoma in two, cerebral toxoplasmosis in one, and resolving cerebral hematoma in one. In the immunocompetent group demyelinating lesions including multiple sclerosis, acute disseminated encephalomyelitis, Balo's concentric sclerosis and acute necrotizing encephalitis, were seen in 11 patients, vascular etiology in four and neoplastic in three patients, two primary and one metastatic and pyogenic brain abscess in one. Ring lesions on diffusion-weighted imaging are associated with a spectrum of disease not previously considered. Immunocompromised patients accounted for almost one-half while demyelinating conditions in the immunocompetent patients were most common overall.

Acute necrotizing encephalopathy (ANE1): rare autosomal-dominant disorder presenting as acute transverse myelitis

The term "acute transverse myelitis (ATM)" comprises various non-traumatic disorders that eventually can be associated with a focal myelopathy. Patients characteristically present with an acutely occurring paraparesis/plegia and require a comprehensive and timely diagnostic work up for the initiation of an appropriate treatment. We present a case of a 36-year-old female patient with a rare genetic disorder (ANE1: Acute Necrotizing Encephalopathy due to a RANBP2 mutation) who presented with an acute quadriplegia. Following an acute pulmonal infection, she rapidly (< 24 h) developed a severe quadriplegia (total motor score 38) with some facial sensory symptoms (perioral hypoesthesia). Magnetic resonance imaging (MRI) revealed a combination of longitudinal extensive transverse myelitis and symmetrical thalamic lesions. A work-up for infectious and systemic diseases was negative; specifically, no findings related to multiple sclerosis, neuromyelitis optica or vascular disorders. After empirical high dose steroid treatment and rehabilitation therapy, the patient gained almost normal gait and upper limb function. She was found to carry an autosomal-dominant missense mutation in the RANBP2 gene predisposing for ANE. Gene segregation was confirmed in other family members that had been affected by other episodes of acute steroid-responsive encephalopathies. We propose that a redefined diagnostic workup of ATM might include ANE1, as the frequency of this rare disorder might be underestimated.

Diagnostic role of target lesion on diffusion-weighted imaging: a case of cerebral aspergillosis and review of the literature

BACKGROUND/PURPOSE

Target lesions on diffusion-weighted imaging are uncommon and their significance not well appreciated. To assess the diagnostic value of this neuroimaging finding, a case of cerebral aspergillosis is presented and the literature reviewed.

METHODS

The diffusion-weighted magnetic resonance imaging features of target lesions in a case of cerebral aspergillosis with neuropathologic correlate is presented and 8 other cases manifesting this neuroimaging finding are reviewed for etiology, patient immune status, lesion number, enhancement, and location.

RESULTS

The etiologies included cerebral aspergillosis, Balo concentric sclerosis, and acute necrotizing encephalopathy. The cerebral aspergillosis cases were immunocompromised with multiple lesions in 4 of 5 patients. The acute necrotizing encephalopathy and Balo concentric sclerosis patients were immunocompetent with bilateral thalamic lesions in the former and multiple random or solitary lesions in the later. Enhancement was seen in 5 patients.

CONCLUSION

Target lesions on diffusion-weighted imaging are compelling for a diagnosis of cerebral aspergillosis in immunocompromised patients and for acute necrotizing encephalopathy in immunocompetent patients when lesions are bilateral thalamic and Balo concentric sclerosis when white matter is involved.

Reversible splenium lesion of the corpus callosum in hemorrhagic fever with renal failure syndrome

This is the first case of virus-associated encephalitis/encephalopathy in which the pathogen was Hantaan virus. A 53-yr-old man presented fever, renal failure and a hemorrhagic tendency and he was diagnosed with hemorrhagic fever with renal failure syndrome (HFRS). In the course of his illness, mild neurologic symptoms such as dizziness and confusion developed and magnetic resonance images revealed a reversible lesion in the splenium of the corpus callosum. This case suggests that HFRS patients with neurologic symptoms like dizziness and mental slowing should be considered to have structural brain lesions and to require brain imaging studies.