Visual hallucinations during wakefulness, at sleep onset (hypnagogic hallucinations) and on awakening (hypnopompic hallucinations) can occur in normal subjects as well as in patients with migraine, epilepsy, mid-brain/thalamic lesions (peduncular hallucinosis), lesions causing visual loss (Charles Bonnet syndrome), sleep paralysis, narcolepsy, and
Parkinson's syndromes . Visual hallucinations can sometimes be highly complex and colorful ("movie-like"). This is well illustrated by the following episode (audiotaped) reported by a 48-year-old man with peduncular hallucinosis due to tegmental midbrain stroke that had appeared after coronary arteriography (Fig. 4):
I suddenly lost the feeling of my own body weight. In front of me I saw—on the right side of the wall—a parade of young and old people that I could not recognize. There was a little girl in front that attracted my attention. She was wearing a very bright dress with red-orange flowers on it like in a painting by Gauguin. I was ready to leave for an adventure. .. when suddenly the voice of the cardiologist woke me up.
Patients are often aware that these hallucinatory phenomena are not real. They may be indifferent to, amused or disturbed by them. In some patients, however, difficulties in differentiating dreaming from hallucinations may be reported. The occurrence of both hallucinations and increased dreaming is also possible . The existence of such a continuum had already been suggested by Lasègue ("le délire alcoolique n'est pas un délire, mais un rêve" .
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