Stroke Hallucinations: Understanding The Unexpected Side Effect

Hallucinations are a known side effect of strokes, occurring in up to one in 20 people. They can manifest in many ways, including visual, auditory, tactile, olfactory, or gustatory forms. Visual hallucinations are the most common type, with patients seeing vivid, colourful scenes of people and animals. These hallucinations are known as peduncular hallucinosis, and they're caused by lesions in the thalamus, a small structure in the middle of the brain. Auditory hallucinations are also common, where patients hear voices, sounds, or music. It's important to note that hallucinations can be distressing and frightening for the person experiencing them. If you or someone you know is experiencing hallucinations after a stroke, it's crucial to seek medical help as soon as possible.

Hallucinations can affect all senses

Hallucinations are false perceptions of sensory experiences. They can be caused by chemical reactions and/or abnormalities in the brain. Hallucinations can affect any of the five senses: sight, sound, smell, touch, and taste.

Visual Hallucinations

Visual hallucinations involve seeing things that aren't there. These hallucinations may be of objects, people, animals, lights, or shapes. For example, a person might see flashing lights that no one else can see, or insects crawling on their hand. Visual hallucinations can also occur due to vision loss, known as Charles Bonnet syndrome, or damage in the mid-brain, known as peduncular hallucinosis.

Auditory Hallucinations

Auditory hallucinations are among the most common types of hallucinations. They involve hearing sounds or voices that aren't real. A person might hear someone speaking to them or telling them to do certain things. The voices may be angry, neutral, or warm. Auditory hallucinations can also include hearing sounds like someone walking or clicking noises.

Olfactory Hallucinations

Olfactory hallucinations involve the sense of smell. A person might smell an unpleasant odour or something pleasant like flowers, but no one else around them can smell it.

Gustatory Hallucinations

Gustatory hallucinations are similar to olfactory hallucinations but involve the sense of taste. These tastes are often strange or unpleasant, such as a metallic taste in the mouth.

Tactile Hallucinations

Tactile hallucinations involve the feeling of touch or movement in the body. For example, a person might feel bugs crawling on their skin or their internal organs moving around. They might also feel the touch of someone's hands on their body.

Hallucinations can be caused by various factors, including mental health conditions such as schizophrenia, dementia, or delirium, substance use, certain medications, physical illnesses like epilepsy, or alcohol use disorder. They can also occur due to stroke damage in areas of the midbrain, known as peduncular hallucinosis.

Hallucinations can be caused by damage to the mid-brain

Hallucinations are a common occurrence after a brain injury, especially in the early stages of recovery. They can be caused by damage to the mid-brain, also known as peduncular hallucinosis. This type of hallucination typically involves vivid and colourful scenes with animals, people, and patterns. They can last from a few minutes to several hours and often occur in the evening. While they can be frightening, it's important to remember that they are not a reflection of one's character but rather the result of neurons firing incorrectly due to brain damage.

Peduncular hallucinosis was first described by a French neurologist in 1922. It is a rare form of visual hallucination that occurs due to lesions or damage in the thalamus, a small structure in the middle area of the brain. This type of hallucination is non-threatening and typically resolves within a few days without the need for pharmacological intervention. However, it is important to seek medical evaluation to rule out other potential causes, especially if new onset hallucinations are present without a prior history of psychiatric issues.

Hallucinations after a brain injury can be intense and distressing. It is crucial to provide support and understanding to the affected individual. Loved ones can help by remaining calm, normalizing the hallucination, and suggesting coping strategies such as reading aloud, listening to music, or humming. It is also helpful to take a picture of the area where visual hallucinations occur, as people often don't see their visions when looking at a photo or video. Arguing or reacting negatively can agitate the person further.

In terms of treatment, antipsychotic medications are typically a last resort due to their potential side effects. Instead, the focus is on allowing the brain to recover, and in some cases, alternative treatments such as psychotherapy or support groups may be recommended. With time and proper management, hallucinations usually become less intense and may even fade away completely.

Hallucinations can be caused by sleep disturbances

Sleep disturbances can indeed cause hallucinations. Sleep deprivation psychosis can cause hallucinations, which are perceptions of something that is not actually present in the environment. It can also cause delusional thinking. This is caused by severe sleep deprivation that continues for a long time.

About 80% of people will hallucinate if they've been severely sleep-deprived, which means getting only a few hours of sleep over one night or going several days without sleep. Most of these incidents involve visual hallucinations.

Sleep disturbances can also cause hypnagogic hallucinations, which are harmless and occur when one is in the state between waking and sleeping. They are not a symptom of mental illness, and experts believe they are simply something the brain does while falling asleep.

In some cases, sleep disturbances can also lead to hypnopompic hallucinations, which are similar to hypnagogic hallucinations but may feel more like an extension of a dream. Sleep paralysis is often associated with both types of hallucinations and can be frightening.

Additionally, sleep disturbances can be a symptom of or be caused by certain prescription medications, anxiety, stress, or other mental health issues. If sleep hallucinations occur frequently and affect one's ability to get enough sleep, it is important to talk to a doctor.

Hallucinations can be caused by occipital lesions

A stroke can sometimes lead to hallucinations or delusions, which may happen in up to one in 20 people. Hallucinations are false perceptions that can affect any of the senses. They can be visual, auditory, olfactory, or tactile. Visual hallucinations can be caused by lesions anywhere in the visual pathway, including the retina, brainstem pathways, and occipital lobe.

Occipital Lobe Lesions and Hallucinations

Occipital lobe lesions can cause visual hallucinations, specifically in the form of object fragments such as lines, corners, and patterns. These hallucinations likely occur due to the pathological activation of neural ensembles in the regions bordering the occipital lesion. This activation may be caused by feedback projections in the earliest visual association cortices, which normally produce meaningful patterns during memory recall.

Other Types of Lesions and Hallucinations

Lesions in other areas of the brain can also lead to hallucinations. For example, lesions in the thalamus have been associated with a rare form of visual hallucination known as peduncular hallucinosis, which involves colourful, non-threatening visions of people and animals. Additionally, temporal lobe lesions are the most common type associated with auditory hallucinations, while parietal lobe lesions are linked to somatic hallucinations such as pain, paresthesia, and complex somatoparaphrenia.

Alzheimer's Disease and Occipital Atrophy

In Alzheimer's disease, visual hallucinations may be associated with neuropathology of the occipital lobe. Patients with visual hallucinations had a significantly smaller ratio of occipital volume to whole-brain volume compared to those without such hallucinations. This suggests that atrophy or degeneration of the occipital lobe may play a role in the development of visual hallucinations in Alzheimer's patients.

Hallucinatory episodes can be brief

Hallucinations can be brief, lasting only a few minutes or a few days. For example, a 75-year-old man was admitted to the hospital with symptoms of a stroke. While recovering, he experienced hallucinations, which resolved in two days without pharmacological intervention.

Hallucinations can also be more long-lasting. For instance, a 53-year-old woman presented at the hospital with a 6-week history of progressive visual hallucinations and delusions. She had suffered an ischemic stroke 7 months prior. Her hallucinations and delusions remitted after treatment with risperidone.

In general, the onset of hallucinations can be sudden, or they can occur weeks or months after a stroke. They can affect any of the senses and are usually very vivid and feel real. Most people with hallucinations do not realize they are not. While some hallucinations can be pleasant, others can be frightening and disruptive.

Visual hallucinations are relatively frequent in patients with acute stroke and are typically self-limited. However, they can last for several months. Auditory hallucinations can also occur in strokes affecting the auditory centres in the brain, located in the temporal lobes.

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