Viral infections chronic parenchymal disorders

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Similar to SSPE with a fatal outcome, caused by rubella virus.

Presents at a later age (10-15 years) Progressive dementia. Ataxia. Spasticity. Myoclonus.

Treatment: No effective treatment

CSF shows high y globulin. EEG does not show periodic complexes of SSPE. Antibodies elevated in serum and CSF to rubella. Biopsy does not show inclusion bodies.



Fatal conditions characterised by the accumulation of a modified cell membrane protein - Prion protein or PrP (proteinaceous infectious particle) within the central nervous system.

Clinical features are dependent on site and rate of deposition of PrP. A similar disorder in cattle, bovine spongiform encephalopathy (BSE) may be a source of infection in man.

The Prion theory

Experimental and epidemiological evidence supports transmissibility. Physical properties of the infective agent -heat and radiation resistance and absence of nucleic acid - suggests it is comprised solely of protein. This infectious protein when innoculated modifies normal cell membrane protein which acts as a template for further conversion to abnormal protein. This host-encoded protein accumulates without any inflammatory or immune response. In familial cases a point mutation in the prion gene explains disease susceptibility.

Creutzfeldt-Jacob disease (CJD)

A worldwide disorder with incidence 1:1000000. Familial cases account for 10-15%. Age of onset 50-60 years. Non specific symptoms at onset (anxiety and depression) are rapidly followed by myoclonus, ataxia, akinetic rigid state, dementia. Death within 12 months is usual. A new variant (possibly linked to BSE) has been described in younger patients with a slower time course. Iatrogenic disease occurs following corneal or dural grafts, depth electrodes and cadaveric derived human growth hormone treatment.


CSF - usually normal.

EEG - bilateral high voltage sharp waves on a background of slow wave activity. The clinical picture and electroencephalogram suggest the diagnosis only ultimately confirmed at postmortem. — -


No abnormality is seen on gross examination Microscopically - Neuronal degeneration occurs with marked astrocytic proliferation and amyloid plaque formation. Vacuolation of glial cells results in a characteristic spongiform appearance. Presymptomatic testing in subjects with family history is available.

Treatment - none available


Gerstmann Straussler syndrome (GSS)

A similar disorder condition to CJD. Cases are familial and characterised by specific pathology of spongiform changes associated with amyloid plaques containing PrP immunoreactive proteins. Clinical features are nonspecific - ataxia, Parkinsonism, dementia. Death occurs within 5 years of contact.


An extensively studied disorder of Papua, New Guinea. It is of interest in view of man to man spread from cannibalism.

Prions may have a role to play in other neurodegenerative disorders, e.g. Alzheimer's disease, Parkinson's disease 490 and motor neurone disease.

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