The duration of these hallucinations varies. Some patients describe very short periods of the disturbance, lasting minutes to hours and corresponding with the onset of their stroke. Others experience prolonged hallucinations, which frequently evolve into formed, complex images, lasting from days to months.6 In the setting of cortical stroke, patients may be at risk for seizures, which could manifest as visual hallucinations. It is essential to ensure that epileptic causes of hallucinations have been ruled out, because seizures may require treatment and other precautions.
Other stroke locations
Strokes in other locations also can result in psychiatric or behavioral symptoms. Acute stroke in the subcortical midbrain or thalamus may result in peduncular hallucinosis, a syndrome of vivid visual hallucinations.7 The midbrain (most commonly the reticular formation) is usually affected; however, certain lesions of the thalamus may also cause peduncular hallucinosis. This phenomenon is theorized to be due to an increase in serotonin activity relative to acetylcholine and is often accompanied by drowsiness.
The subthalamic nucleus is most frequently associated with disordered movement such as hemiballismus, but also causes disturbances in mood and behavior, including hyperphagia and personality changes.8 Irritability, aggressiveness, disinhibition, anxiety, and obscene speech may also be seen with lesions of the subthalamic nucleus.
Finally, the caudate nucleus may cause alterations in executive functioning and behavior.9 A stroke in the dorsolateral caudate may cause abulia and psychic akinesia, decreased problem-solving ability, reduced abstract thinking, and/or diminished spontaneity, whereas an infarct in the ventromedial region of the nucleus may cause disinhibition, disorganization, impulsiveness, and, in severe cases, affective symptoms with psychosis.10 Strokes in any of these areas are at risk for being misdiagnosed because patients may not have a hemiparesis, and isolated positive or psychiatric symptoms may not be recognized as stroke.
Symptoms not related to stroke location
Delirium and psychosis
Following a stroke, a patient may exhibit neuropsychiatric symptoms that do not appear to relate directly to the anatomical structures affected by the infarct. In the acute phase, factors such as older age and medical complications (including infection, metabolic derangement, and lack of sleep due to frequent neurologic checks) create a high risk of delirium.11 Differentiating delirium from alterations in mental status due to seizure, cerebral edema, or other medical complications is essential, and delirium precautions should be exercised to the greatest extent possible. Other neuropsychiatric symptoms may manifest following hospitalization.
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