A 10-month-old girl was referred to the emergency department for acute cardiopulmonary failure in the context of myocarditis. She presented acute flaccid paralysis, respiratory distress, and ophthalmoplegia.
Lumbar puncture for CSF analysis was not performed because blood tests revealed a coagulation disorder (INR = 2.33) due to her shock.
Unenhanced T2-weighted brain MR images show a symmetric hyperintensity along the tegmentum of the brainstem from the midbrain to the medulla oblongata that extends downwards to the cervical spinal cord and upwards to the hypothalamus (Fig.1a-d).
These lesions show homogeneous restriction diffusion on DWI and respective ADC maps (Fig. 2a-e).
No other supratentorial lesions were identified (findings not shown).
T2-weighted MR image of the spine show a long lesion involving the entire central gray matter of the spinal cord extending uniformly along the cervical spine (Fig. 3).
Follow-up T2-weighted MR images of the spine 21 days later show the hyperintensity has contracted and involves only some foci in the anterior horns (Fig. 4a-b).
The definitive diagnosis was obtained by a positive Enterovirus A71 polymerase chain reaction (PCR) from throat-swab and stool specimens.
The child died 5 weeks after admission.
Enterovirus infections are common; most are asymptomatic or have a benign course and nonneurologic manifestations. Enterovirus A71 (EV-71) infection can be associated with acute neurologic disorders in young children. Most children have a previous infectious condition, such as hand-foot-and-mouth disease or herpangina. Rhombencephalitis and anterior horn myelitis are uncommon complications of EV-71 infection that can cause serious neurological complications or even death. The incidence of EV-71 infection varies throughout the year and peaks during the summer.
Neurological symptoms are associated with brainstem or spinal cord lesions; these symptoms include myoclonus, tremor or ataxia, limb weakness or acute flaccid paralysis, and cranial nerve dysfunction (ophthalmoplegia, facial palsy, or dysphagia), as well as respiratory or circulatory dysfunction, even acute cardiopulmonary collapse and altered mental status. [1-5]
The MRI findings are very characteristic. T2-weighted images show hyperintensity affecting the dorsal brainstem and a long segment of the cervical spinal cord, with a predilection for the anterior horns. The most common site of brainstem involvement is the pontine tegmentum. Supratentorial lesions are uncommon, but sometimes these lesions can extend upwards to the hypothalamus or thalamus. Some cases show involvement of the substantia nigra or dentate nucleus. Restricted diffusion is seen in the acute phase. We didn´t obtain contrast-enhanced T1 weighted sequences in our MRI study but enhancement of nerve roots, anterior horn cells, or the brainstem may also been seen. In the acute phase, spinal cord hyperintensities are ill-defined, involving the entire gray matter of the central spinal cord. In the subacute phase, T2 hyperintensities are more restricted to the anterior horns [1-5]
The definitive diagnosis can be made by PCR detection of viral DNA in throat-swab and/or stool specimens or CSF.
No curative treatments are available. EV-71 encephalomyelitis is associated with significant morbidity and mortality rates.
Neuroimaging features are very similar to other enterovirus encephalomyelitides, such as enterovirus D68 or poliovirus. [6-8]
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