Stroke-Induced Hallucinations: Understanding The Unexpected Side Effect

Hallucinations are a known symptom of several mental health conditions, but they can also be caused by a stroke. Hallucinations are vivid sensations that feel real and can be seen, heard, felt, smelt or tasted. They are caused by damage to the brain, and can occur after a stroke, sometimes even several months later. This is known as poststroke psychosis, and it can be very frightening for the person experiencing it.

Hallucinations can occur with or without prior psychiatric history

Hallucinations can occur after a stroke, with or without prior psychiatric history. Post-stroke hallucinations can be visual, auditory, or both, and they can occur in up to one in 20 people. They can be caused by damage to the brain, specifically the midbrain, thalamus, or occipital cortex.

Visual hallucinations after a stroke are known as peduncular hallucinosis, a rare form of hallucination first described by a French neurologist in 1922. They are characterised by colourful, non-threatening visions of people and animals. These hallucinations are associated with lesions in the thalamus, a small structure in the middle of the brain. They can also be caused by damage to the occipital cortex, which is located in the occipital lobe, or the visual centre of the brain.

Auditory hallucinations after a stroke are uncommon and are usually associated with lesions of the brain stem. They can also occur after cortical strokes, specifically lesions of the right temporal lobe.

The onset of hallucinations can vary, starting soon after a stroke or even weeks or months later. They can be temporary, lasting only a few weeks, or they may persist for several months. In some cases, hallucinations may resolve without pharmacological intervention. However, it is important to seek medical help as early treatment is often more effective.

Hallucinations can be visual, auditory, tactile, olfactory or gustatory

Hallucinations are a known symptom of strokes, occurring in up to one in 20 people. They can manifest through any of the senses and may start soon after a stroke or even weeks or months later.

Hallucinations can be visual, meaning the patient sees things that aren't there. For example, a 75-year-old man recovering from a stroke described seeing his wife sleeping on his hospital bed, his dogs, and a TV show playing on a switched-off television. Visual hallucinations can also occur due to vision loss, known as Charles Bonnet syndrome, where the brain generates images to fill in missing areas of the patient's field of vision. These hallucinations can be temporary, lasting several months, and can appear as simple patterns or complex images of people, places, and objects.

Auditory hallucinations are also possible, where patients hear sounds, voices, music, or odd noises. These are less common, but they can be a direct result of acute strokes, particularly when there are lesions in the brain stem or right temporal lobe.

Tactile hallucinations can cause patients to feel something crawling on their skin, for instance. Olfactory hallucinations can invoke the smell of burning rubber, and gustatory hallucinations can also occur, although these are less commonly mentioned.

Visual hallucinations are relatively frequent in patients with acute stroke

Visual hallucinations are indeed relatively common in patients with acute stroke, with an incidence of 16.7% in one study. These hallucinations are usually complex and in black and white, and they tend to be self-limited, meaning they resolve on their own without intervention. Visual hallucinations are more likely to occur in patients with occipital lesions and sleep disturbances.

Visual hallucinations can result from strokes occurring in the visual centers of the brain, located in the occipital lobes, or in the brain stem. In the case of occipital lesions, the hallucinations tend to be in black and white and are associated with sleep disturbances. With brain stem lesions, the hallucinations are typically colourful and non-threatening, often involving visions of people and animals. This type of hallucination is known as peduncular hallucinosis and was first described by a French neurologist in 1922.

It is important to note that hallucinations after a stroke are not always visual. Auditory hallucinations, for example, those involving hearing sounds or voices, can also occur, particularly with lesions of the brain stem or right temporal lobe. However, visual hallucinations are certainly the most common type, and they can be a distressing and disruptive symptom for those affected.

The mechanism behind visual hallucinations in stroke patients is not yet fully understood. One theory suggests that it is due to a "release" of the brain areas that normally process images. Normally, visual stimuli sent from the retina to the brain prevent the brain from processing any image other than what is currently being seen. However, when the eye is damaged or diseased, this control is lost, and the brain may generate images to fill in missing areas of vision.

If you or someone you know is experiencing hallucinations after a stroke, it is important to seek medical advice. While hallucinations may resolve on their own, early treatment can be more effective, and medical professionals can provide support and guidance.

Auditory hallucinations are uncommon phenomena directly caused by acute stroke

Auditory hallucinations are uncommon phenomena that can be directly caused by acute stroke. They are usually described after lesions of the brain stem but are very rarely reported after cortical strokes. In a study of 641 stroke patients, only four patients were found to have post-cortical stroke auditory hallucinations. All four cases occurred after an ischemic lesion of the right temporal lobe.

Auditory hallucinations can be a symptom of psychosis, which can occur after a stroke. Psychosis is an umbrella term for fixed beliefs that are not amenable to change in light of conflicting evidence and abnormal perceptions that are not experienced by others. The incidence of psychotic symptoms after a stroke ranges from 1% to 5.3%. However, when present in patients with no previous psychiatric history, these symptoms tend to be underdiagnosed and undertreated.

Visual hallucinations are more common in patients with acute stroke than auditory hallucinations. In one study, the incidence of visual hallucinations was 16.7%. Visual hallucinations are associated with occipital cortex lesions and sleep disturbances. They are usually self-limited and may last for several months before reducing.

Another type of hallucination that can occur after a stroke is peduncular hallucinosis, a rare form of visual hallucination that includes colourful, non-threatening visions of people and animals. This type of hallucination is usually tied to lesions in the thalamus, a small structure in the middle area of the brain.

Post-stroke psychosis is associated with higher mortality rates

Post-stroke psychosis is associated with a significantly higher mortality rate. Patients with post-stroke psychosis are 51% more likely to die within 10 years than patients without psychosis after stroke. The mortality rate for patients with post-stroke psychosis is much higher, and the condition is linked to a poorer quality of life.

Post-stroke psychosis is challenging to treat due to the limited treatment options and the risks associated with medications. The most common treatment modality for post-stroke psychosis is antipsychotics. However, the risk of stroke increases with the use of antipsychotics. There is a lack of clinical investigations and longitudinal therapeutic investigations to address the pathology associated with post-stroke psychosis and explore pharmacotherapies to improve treatment efficacy and safety.

Post-stroke psychosis is more common than previously recognized, with an incidence of 1% to 5.3%. It is more prevalent in patients with right-hemisphere lesions, particularly in the frontal, temporal, and parietal regions. The average age for the occurrence of post-stroke psychosis is 66.6 years, and it is more prevalent in men than in women.

The most common types of psychosis after stroke are delusional disorder, schizophrenia-like disorder, and mood disorders with psychotic features. The most common type of delusion is persecutory delusion, followed by delusional jealousy, reduplicative paramnesia, and somatic delusions. The average time to complete resolution of post-stroke psychosis is 3.5 months.

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