Subacute Sclerosing Panencephalitis Presenting with Unilateral Periodic Myoclonic Jerks

Abstract

It occurs in one of three distinct types; 1) postinfectious or autoimmune encephalomyelitis, which presents as a sudden recurrence of fever with an altered level of consciousness, seizure activity, and multifocal neurological signs, 2) subacute measles encephalitis (SME; also called subacute inclusion body encephalopathy and progressive infections measles encephalitis) occurring in immunosuppressed patients 1-10 months after measles infection, and 3) subacute sclerosing panencephalitis (SSPE), which presents after six or more years from an acute measles infection with the onset of neurological dysfunction ABSTRACT: Background: Subacute sclerosing panencephalitis (SSPE) is a rare complication of measles virus infection. The disease is characterized by behavioural abnormalities, intellectual deterioration, motor weakness, and generalized myoclonic jerks progressing to coma and death in one to two years in 80% of the cases. The myoclonic jerks are associated with characteristic generalized slow periodic complexes on electroencephalography (EEG). The symptoms and signs of SSPE are frequently quite variable. The clinical course is equally variable and difficult to predict. The characteristic periodic myoclonus can rarely occur unilaterally particularly in the early stages of the disease. As well, the periodic EEG complexes have been reported unilaterally in up to 3% of cases. Case Report: A 12-year-old boy, who was seen at a later stage with atypical manifestation of myoclonic body jerks confined entirely unilaterally, combined with contralateral periodic EEG complexes. One could assume clinically that the more diseased hemisphere was responsible for generating the jerks. However, brain magnetic resonance imaging revealed asymmetric hemispheric changes suggesting that the less neurologically damaged hemisphere is responsible for generating the unilateral myoclonic jerks. This has led to the interpretation that the more severely damaged hemisphere has lost the neuronal connectivity required to generate these periodic myoclonic jerks. Conclusions: Subacute sclerosing panencephalitis may have asymmetric hemispheric involvement, not only early, but also in the advanced stages of the disease, which can result in unilateral periodic myoclonic jerks.

Senile-Onset Subacute Sclerosing Panencephalitis, Presenting With Peculiar Findings

“…It is also possible that the periodic complexes can appear lateralized in the late term as the more severely affected hemisphere is incapable of generating them. 8 In our case, the periodic complexes were more prominent on the hemisphere previously affected by the stroke. A possible explanation for this is that the disease might start asymmetrically, as shown by the imaging findings of the former studies, and that lateralized discharges might be a reflection of this phenomenon.…”

Periodic Lateralized Epileptiform Discharges in Fulminant Form of SSPE

“…The clinical course in our patient was also atypical in that it was very rapid, with initial presentation as unilateral myoclonus along with weakness. Such an asymmetric presentation has been rarely reported earlier 8 . Ekmekci et al studied 22 patients with definite SSPE with atypical EEG abnormalities in relationship to the clinical features 9 .…”

“…Focal discharges in EEG are an uncommon finding in a global encephalitis like SSPE 8 . Hence presence of PLEDs at some stage of the disease process in SSPE would suggest a preferential involvement of one hemisphere.…”

Infectious Diseases

“…This initial phase (stage I) may last for weeks to months and occasionally longer. 2,33,34 Stereotyped motor spasms (slow myoclonic jerks) may precede, accompany, or follow the periodic complexes. Other features noted during this phase may include seizures, chorioretinitis, optic atrophy, ataxia, and dystonia.…”