- After stroke, hallucinations are usually visual.
- It is difficult to know how many people experience hallucinations as they are under-reported due to the association with mental illness.
- Hallucinations range from people seeing simple shapes and colours to complex scenes (Charles Bonnet syndrome). Ref: De Haan, Edward H.; Nys, Gudrun M.; van Zandvoort, Martine J.; Ramsey, Nick F. The physiological basis of visual hallucinations after damage to the primary visual cortex, NeuroReport: July 16, 2007 -Volume 18 – Issue 11 – p 1177-1180 doi:10.1097/ WNR.0b013e32820049d3
- Hallucinations are associated with damage to the occipital lobe or the brainstem and thalamic areas of the brain.
- Stroke patients are usually aware that their hallucinations are not real.
- Three theories try to explain why hallucinations happen after stroke:
- the damaged areas of the occipital lobes no longer inhibit the undamaged areas resulting in increased visual activity
- there is increased firing of neurons from the scar tissue of damaged areas
- there is less competition from damaged areas of the brain which reduces the threshold from which hallucinations can happen
- Hallucinations usually fade after several weeks.
Links to further reading:
Charles Bonnet leaflet [PDF, 27KB] (with permission of the British & Irish Orthoptic Society)
Page last reviewed: 29 Jul 2021
