Reversible processes

• Non-convulsive status epilepticus

• Cerebral vasculitis/other inflammatory conditions

• Non-inflammatory cerebrovascular disease

• Drug toxicities (especially lithium)

• Tuberculosis/fungal meningitis

• Parenchymal Whipple’s disease

• Chronic subdural haematoma/cerebral tumour

• Paraneoplastic limbic encephalitis (may improve with treatment of tumour)

• Antivoltage gated potassium channel antibody syndrome⁵⁹

• ?Hashimoto’s encephalopathy

Irreversible processes

• Rapidly progressive neurodegenerative variants:

• Dementia with Lewy bodies, multiple system atrophy, Alzheimer’s disease

• Dementia (motor neurone disease) syndromes

• Neurofilament inclusion body disease²³

• Prion diseases:

  • Sporadic, familial, and new variant Creutzfeldt-Jakob disease

  • Progressive multifocal leukoencephalopathy

  • Subacute sclerosing panencephalitis (sequela of measles)