Subacute sclerosing panencephalitis: brain stem involvement in a peculiar pattern

Subacute sclerosing panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a slowly progressive brain disorder caused by mutant measles virus. SSPE affects younger age groups. SSPE incidence is proportional to that of measles. High-income countries have seen substantial decline in SSPE incidence following universal vaccination against measles. SSPE virus differs from wild measles virus. Measles virus genome recovered from the autopsied brain tissues demonstrates clustered mutations in virus genome particularly in the M gene. These mutations destroy the structure and functioning of the encoded proteins. Complete infectious virus particle has rarely been recovered from the brain. Human neurons lack required receptor for entry of measles virus inside the neurons. Recent in vitro studies suggest that mutations in F protein confer hyperfusogenic properties to measles virus facilitating transneuronal viral spread. The inflammatory response in the brain leads to extensive tissue damage. Clinically, SSPE is characterized by florid panencephalitis. Clinically, SSPE is characterized by cognitive decline, periodic myoclonus, gait abnormalities, vision loss, and ultimately to a vegetative state. Chorioretinitis is a common ocular abnormality. Electroencephalography (EEG) shows characteristic periodic discharges. Neuroimaging demonstrates periventricular white matter signal abnormalities. In advanced stages, there is marked cerebral atrophy. Definitive diagnosis requires demonstration of elevated measles antibody titers in cerebrospinal fluid (CSF). Many drugs have been used to stabilize the course of the disease but without evidence from randomized clinical trials. Six percent of patients may experience prolonged spontaneous remission. Fusion inhibitor peptide may, in the future, be exploited to treat SSPE. A universal vaccination against measles is the only proven way to tackle this menace currently.

Subacute Sclerosing Panencephalitis of the Brainstem as a Clinical Entity

Subacute sclerosing panencephalitis (SSPE) is a rare progressive neurological disorder of early adolescence caused by persistent infection of the measles virus, which remains prevalent worldwide despite an effective vaccine. SSPE is a devastating disease with a characteristic clinical course in subcortical white matter; however, atypical presentations of brainstem involvement may be seen in rare cases. This review summarizes reports to date on brainstem involvement in SSPE, including the clinical course of disease, neuroimaging presentations, and guidelines for treatment. A comprehensive literature search was performed for English-language publications with keywords “subacute sclerosing panencephalitis” and “brainstem” using the National Library of Medicine PubMed database (March 1981–September 2017). Eleven articles focusing on SSPE of the brainstem were included. Predominant brainstem involvement remains uncharacteristic of SSPE, which may lead to misdiagnosis and poor outcome. A number of case reports have demonstrated brainstem involvement associated with other intracranial lesions commonly presenting in later SSPE stages (III and IV). However, brainstem lesions can appear in all stages, independent of higher cortical structures. The varied clinical presentations complicate diagnosis from a neuroimaging perspective. SSPE of the brainstem is a rare but important clinical entity. It may present like canonical SSPE or with unique clinical features such as absence seizures and pronounced ataxia. While SSPE generally progresses to the brainstem, it can also begin with a primary focus of infection in the brainstem. Awareness of varied SSPE presentations can aid in early diagnosis as well as guide management and treatment.

Subacute sclerosing panencephalitis presenting as acute cerebellar ataxia and brain stem hyperintensities

BACKGROUND

Subacute sclerosing panencephalitis is a devastating neurodegenerative disease with a characteristic clinical course. Atypical presentations may be seen in 10% of the cases.

AIMS

To describe the atypical clinical and radiological features of SSPE in a child form endemic country.

METHODS

A 5-year-old boy presented with acute-onset cerebellar ataxia without associated encephalopathy, focal motor deficits, seizures or cognitive decline. He had varicella-like illness with vesicular, itchy truncal rash erupting one month prior to the onset of these symptoms. He underwent detailed neurological assessment, relevant laboratory and radiological investigations.

RESULTS

Neuroimaging revealed peculiar brain stem lesions involving the pons and cerebellum suggestive of demyelination. With a presumptive diagnosis of clinically isolated syndrome of demyelination, he was administered pulse methylprednisolone (30 mg/kg/day for 5 days). Four weeks later he developed myoclonic jerks. Electroencephalogram showed characteristic periodic complexes time-locked with myoclonus. CSF and serum anti-measles antibody titres were elevated (1:625).

CONCLUSION

Our report highlights that subacute sclerosing panencephalitis can present atypically as isolated acute cerebellar ataxia and peculiar involvement of longitudinal and sparing of transverse pontine fibres. The predominant brainstem abnormalities in the clinical setting may mimick acute demyelinating syndrome. Hence, it is important to recognize these features of subacute sclerosing panencephalitis in children, especially in the endemic countries.

Blindness, dancing extremities, and corpus callosum and brain stem involvement: an unusual presentation of fulminant subacute sclerosing panencephalitis

A 4-year-old girl presented with acute visual loss followed 2 weeks later with loss of speech and audition, fulminant neuroregression, and choreo-athetoid movements of extremities. Fundus showed bilateral chorioretinitis. Electroencephalography showed periodic complexes. Measles antibody titers were elevated in both serum and cerebrospinal fluid, consistent with subacute sclerosing panencephalitis. Neuroimaging showed discontiguous involvement of splenium of the corpus callosum and ventral pons with sparing of cortical white matter. Our case highlights the atypical clinical and radiologic presentations of subacute sclerosing panencephalitis. Pediatricians need to be aware that necrotizing chorioretinitis in a child and/or atypical brain stem changes could be the heralding feature of this condition in endemic countries.

Subacute sclerosing panencephalitis (SSPE) presenting as acute disseminated encephalomyelitis in a child

Subacute sclerosing panencephalitis (SSPE) typically presents with progressive mental deterioration, behavioral changes, and myoclonic jerks. Atypical presentations are not unknown and may result in diagnostic delays. A 9-year-old girl presented with poor balance and ataxia following an episode of upper respiratory tract infection. Neurological examination revealed mild hemiparesis and ataxia. Brain magnetic resonance imaging revealed scattered areas of T2 and fluid-attenuated inversion recovery hyperintensities in the white matter consistent with acute disseminated encephalomyelitis. Despite treatment with intravenous methylprednisolone, intravenous immunoglobulins, and plasmapheresis, progressive neurological worsening occurred. Later during the course of her illness, subacute sclerosing panencephalitis was suspected from the appearance of burst-suppression pattern on electroencephalogram, and the diagnosis confirmed by elevated titers of measles antibodies in cerebrospinal fluid. Physicians taking care of children need to be aware of atypical presentations of subacute sclerosing panencephalitis and must have a high index of suspicion to prevent diagnostic delays and avoid unnecessary diagnostic and therapeutic interventions.

MR imaging, diffusion-weighted imaging and MR spectroscopy findings in acute rapidly progressive subacute sclerosing panencephalitis

We are presenting two cases with subacute sclerosing panencephalitis of acute and rapid form, which were initially diagnosed as acute viral encephalitis. We obtained both diffusion-weighted imaging and magnetic resonance spectroscopy, whose findings suggested the presence of acute inflammatory and metabolic changes with peculiar distribution, which were not observed on conventional MR imaging. These techniques might help to demonstrate the extent and progression of the panencephalitis.

Subacute Sclerosing Panencephalitis with Pontine Involvement

In subacute sclerosing panencephalitis, brainstem involvement is rare. This paper reports an 11-year-old boy with the disease with prominent pontine involvement. Diffusion magnetic resonance imaging had superior information with respect to involvement of the nerve fibers. In the ventral part of the pons, the regions containing the longitudinal pontine nerve bundles were spared bilaterally and symmetrically. The pontine tegmentum was also spared. High signal in the affected regions was revealed by b = 1000 s/mm2 images. The apparent diffusion coefficient values in these regions were low, ranging between 0.43 x 10(-3) to 0.54 x 10(-3) mm2/s. Those of the spared tegmentum and longitudinal bundles were normal, ranging between 0.89 x 10(-3) to 1.04 x 10(-3) mm2/s, compared with the values from the normal-appearing regions of the cerebellar parenchyma.

Magnetic resonance imaging of mesenrhombencephalitis

Mesenrhombencephalitis is a rare inflammatory process involving the midbrain, pons, and medulla. The diagnosis is difficult as clinical and laboratory findings may be nonspecific. Magnetic resonance (MR) imaging demonstrates abnormal T2 signal in the brainstem, which can suggest the diagnosis. The clinical, laboratory and MR imaging findings are described in five patients with this serious, life-threatening disease. MR imaging can be of value in the early diagnosis of this rare disorder.