Acute flaccid myelitis: cause, diagnosis, and management

Acute flaccid myelitis (AFM) is a disabling, polio-like illness mainly affecting children. Outbreaks of AFM have occurred across multiple global regions since 2012, and the disease appears to be caused by non-polio enterovirus infection, posing a major public health challenge. The clinical presentation of flaccid and often profound muscle weakness (which can invoke respiratory failure and other critical complications) can mimic several other acute neurological illnesses. There is no single sensitive and specific test for AFM, and the diagnosis relies on identification of several important clinical, neuroimaging, and cerebrospinal fluid characteristics. Following the acute phase of AFM, patients typically have substantial residual disability and unique long-term rehabilitation needs. In this Review we describe the epidemiology, clinical features, course, and outcomes of AFM to help to guide diagnosis, management, and rehabilitation. Future research directions include further studies evaluating host and pathogen factors, including investigations into genetic, viral, and immunological features of affected patients, host-virus interactions, and investigations of targeted therapeutic approaches to improve the long-term outcomes in this population.

Acute Flaccid Myelitis With Neuroradiological Finding of Brachial Plexus Swelling

BACKGROUND

Acute flaccid myelitis is a recently defined clinically distinct syndrome of polio-like acute flaccid paralysis. Acute flaccid myelitis cases show characteristic neuroradiological features of longitudinal spinal cord lesions with predominant gray matter involvement. Current evidence suggests injury to the anterior horn neurons as the underlying mechanism.

METHODS

We describe three patients with acute flaccid myelitis who developed flaccid upper limb weakness with diminished deep tendon reflexes after prodromal fever. Spinal magnetic resonance imaging (MRI) (axial and sagittal T1- and T2-weighted sequences) and brachial plexus MRI (coronal short tau inversion recovery sequence) at the acute stage were performed.

RESULTS

Spinal MRI showed extensive longitudinal lesion in the spinal cord with predominant gray matter involvement. We were able to demonstrate concurrent swelling and hyperintensity in the brachial plexus in all the three patients at the acute stage.

CONCLUSION

The coexisting signal intensities suggest an extension of acute flaccid myelitis pathology to the brachial plexus, highlighting the possible peripheral nerve involvement in acute flaccid myelitis.

COVID-19: A primer for Neuroradiologists

The potential for central nervous system (CNS) involvement in coronavirus disease 2019 (COVID-19) is a matter of grave concern and there is a relevant body of evidence in the basic sciences to support this possibility. A neuroradiologist should be aware of the potential mechanisms involved in the neuropathogenesis of this virus, as we begin to see cases with abnormal brain scans emerging from all parts of the world.

Expression of neurotrophic factors in cerebrospinal fluid and plasma of children with viral and bacterial meningoencephalitis

AIM

To evaluate the expression of neurotrophic factors (nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF)) and their association with the clinical-radiological characteristics and outcome of children with viral and bacterial meningoencephalitis (ME).

METHODS

Prospective observational clinical study performed on 13 children with ME and 12 controls with non-inflammatory obstructive hydrocephalus. Neurotrophic factor levels in the cerebro-spinal fluid (CSF) and plasma were measured using an immunoenzymatic assay.

RESULTS

High levels of NGF and BDNF were demonstrated in all patients, while GDNF levels did not undergo significant variations. NGF expression in the CSF was higher in viral ME than in bacterial ME and was correlated with CSF cellularity (particularly mononuclear cells). BDNF expression in the CSF was higher in bacterial ME than in viral ME and was correlated with CSF cellularity and blood platelet count. No relationships were noted between CSF protein or serum C-reactive protein levels and the expression of neurotrophic factors. Regarding clinical and radiological features, elevated NGF/BDNF levels in the CSF correlated with higher incidence of seizures and prolonged comatose state and with specific radiological lesions. No correlation was found between NGF/BDNF levels and final outcome.

CONCLUSIONS

The variations in neurotrophic factor levels may reflect an endogenous attempt at neuroprotection against biochemical and molecular changes during both viral and bacterial ME. The expression of these factors is likely to play a neuro-immunomodulatory or neurosurvival role in ME infections.

Cranial viral infections in the adult

Viral infections of the adult are fortunately rare conditions but may carry serious clinical sequelae. Infection is usually acquired by haematogenous spread during a systemic viral illness and may be acute, subacute or chronic. The pathological basis of neuronal degeneration and attempt to repair is common to all illnesses and diagnosis is generally made by analysis of the pattern of disease. Magnetic resonance imaging is now the mainstay of imaging diagnosis. Acute infections include encephalitis due to a wide range of infecting agents and outcome depends on the severity of the acute episode. Subacute and chronic infections, including HIV encephalopathy, most often produce a progressive leucoencephalopathy and ultimately cerebral atrophy. Additionally, disease may also be immune mediated, that most closely associated with viral infection being acute disseminated encephalomyelitis, which is usually a monophasic illness. Finally, prion diseases are characterised by long incubation period and progressive course, leading to death.