Progressive Rubella Panencephalitis

Progressive rubella panencephalitis is a very rare, fatal, slowly progressive encephalitis from persistent rubella virus, appearing 8 to 19 years after congenital rubella syndrome or, rarely, postnatal rubella. Fewer than 30 cases are described.

Pathophysiology. Persistent rubella virus infection with immune complex deposition and chronic inflammation causes perivascular inflammation, loss of neurons and gliosis. Intrathecal antibody production is raised.

Onset is in the second decade with declining school performance, behaviour change, dementia, progressive ataxia, spasticity, dysarthria, seizures and myoclonus. Features of congenital rubella are often present: deafness, cataract, retinopathy ("salt and pepper") and cardiac disease. Progression to vegetative state and death takes 2 to 8 years.

Red flags.

• Cognitive and motor decline in an adolescent with known congenital rubella.

CSF shows raised protein, raised gamma globulin, oligoclonal bands and high rubella specific IgG with an elevated intrathecal antibody index. Rubella RNA may be detected in CSF by PCR. MRI shows cerebral and cerebellar atrophy with white matter change. EEG shows slowing with periodic complexes less distinct than in measles encephalitis. Brain biopsy is rarely needed.

Differential diagnosis.

• Subacute sclerosing panencephalitis (measles antibodies differ).
• Leukodystrophies, neuronal ceroid lipofuscinosis and other neurodegenerative diseases.
• Autoimmune encephalitis and HIV encephalopathy.

No treatment alters the course. Management is supportive.

Seizures and myoclonus. Sodium valproate 10 to 15 mg/kg daily in divided doses, increased to 30 mg/kg daily, or levetiracetam 10 mg/kg twice daily, increased to 30 mg/kg twice daily (adjust to renal function). Clonazepam for myoclonus.

Spasticity. Baclofen starting at 5 mg three times daily, increased gradually (children: 0.3 mg/kg daily in divided doses).

Supportive care. Nutrition and swallowing support, physiotherapy, hearing and vision aids, secretion and skin care, family support and palliative care.

Prevention. Rubella vaccination for children and women of reproductive age before pregnancy, with confirmation of immunity. Rubella vaccine is a live vaccine and is contraindicated in pregnancy.

Referral and escalation. Refer to paediatric neurology and palliative services.