Spectrum of Movement Disorders Among Children With Subacute Sclerosing Panencephalitis: A Cross-Sectional Study

Abstract

Background: Subacute sclerosing panencephalitis is a progressive devastating condition due to persistence of mutant measles virus, affecting children and adolescents, characterised by myoclonus, seizures, and neuropsychiatric issues. Movement disorders apart from myoclonus are reportedly uncommon. We aimed to describe frequency and proportion of movement disorders among children with subacute sclerosing panencephalitis, hypothesizing that these occur more frequently than previously reported. Methods: In this cross-sectional study, we enrolled children with subacute sclerosing panencephalitis between 1 month and 18 years of age who fulfilled the diagnosis of subacute sclerosing panencephalitis as per modified Dyken criteria, and examined them for movement disorders. We also assessed their clinical profile and disease severity via Jabbour staging and modified Rankin Scale score. We compared demographic, clinical, and laboratory features of children with and without movement disorders. Results: We enrolled 50 children (36 males; 72%) (age range 1.5-14 years). Of these, 28 (56%) had movement disorders. Among movement disorders, the most frequent was myoclonus (92%), followed by ataxia (9; 18%), chorea-athetosis (7; 14%), dystonia (6; 12%), tremor (4; 8%), repetitive behavior (4; 8%), and parkinsonism (3; 6%). Movement disorders were the presenting feature of subacute sclerosing panencephalitis among 7 children. There were no significant differences in clinical or laboratory features among children with and without movement disorders. Conclusions: Movement disorders were frequent in subacute sclerosing panencephalitis. Hyperkinetic disorders were dominant. Dystonia and chorea-athetosis occurred more commonly among nonmyoclonus movement disorders. Movement disorders may manifest even in earlier stages of subacute sclerosing panencephalitis and may be the heralding feature. Recognition of these features is important to plan management and reduce morbidity.

Periodic Jaw-Opening Myoclonus in Subacute Sclerosing Panencephalitis

“…Movement disorders are an underrecognized but frequent feature of SSPE. 2 Myoclonus in SSPE is described to be characteristically periodic and stereotyped, usually involving the head, trunk, and limbs. A slow relaxation phase, defying the otherwise rapid shock-like nature of myoclonus, is sine qua non.…”

“…We previously assessed 50 patients with SSPE in a cross-sectional study from Lady Hardinge Medical College, New Delhi, India. 2 The most frequent movement disorders were observed to be myoclonus, ataxia, chorea-athetosis, dystonia, tremor, repetitive behaviors and parkinsonism. Notably, we did not observe the occurrence of jaw myoclonus in this series.…”

“…Movement disorders are also reported. 2 We report the occurrence of a highly unusual jaw-opening myoclonus in a child with SSPE, thereby expanding the phenotypic repertoire of this condition.…”

Jaw Opening Myoclonus in Subacute Sclerosing Panencephalitis

“…A plethora of abnormal movements can occur in SSPE which include myoclonus, dystonia, tremor, chorea, rigidity, bradykinesia, ataxia and stereotypy. 1 The differential diagnosis of myoclonus in children/adults in the presence of EEG changes is rather specific, whereby in some cases findings in EGG may be pathognomonic. Here we present two cases with progressive cognitive impairment, jaw-myoclonus and characteristic EEG findings diagnosed with SSPE.…”

“…Subacute sclerosing panencephalitis (SSPE) or Dawson's encephalitis is a chronic debilitating disorder of the central nervous system characterized by progressive cognitive impairment, myoclonic jerks, extra‐pyramidal symptoms and classical high‐amplitude generalized periodic slow‐wave discharges also known as Rademecker complexes in electroencephalogram (EEG). A plethora of abnormal movements can occur in SSPE which include myoclonus, dystonia, tremor, chorea, rigidity, bradykinesia, ataxia and stereotypy 1 . The differential diagnosis of myoclonus in children/adults in the presence of EEG changes is rather specific, whereby in some cases findings in EGG may be pathognomonic.…”