A medical hypothesis
21 June 2001
Raffaele Manni MD
Istituto di Genetica Biochemica, Pavia, Italy,
Growing evidence suggests REM sleep dysfunction in PD where a high prevalence of REM sleep disorders or excessive daytime sleepiness with REM sleep onset have been observed . In the recent paper by Arnulf et al  it has been suggested that some of the hallucinations occurring in non demented Parkinsonian patients are due to abrupt REM intrusions into wakefulness and should be considered a narcoleptic-like phenomenon. This interesting concept had already been anticipated in 1958 by the Italian neurologists Carlo Berlucchi (1897-1992) and Paolo Pinelli (born 1921) while studying sleep alterations in different abnormal neurological conditions. Since their investigations were published only in local scientific press [3, 4] and are unknown to the neurological community we briefly summarise their findings here. Berlucchi and Pinelli programmed an “EEG investigations in various neuropsychiatric disorders to find out which of these are similar to the EEG sleep dream pattern described by Dement and Kleitman” . The most interesting case studied by Pinelli was that of a woman, age 48 years, affected by post-encephalitic Parkinson disease with tremor and severe rigidity, mild akinesia and diurnal hallucinations. The investigation consisted of a series of clinical and EEG monitoring, in basal conditions, during wakefulness, shortly before the occurrence of diurnal hallucination, during and after their occurrence. In Pinelli’s words: “The woman, undergoing EEG registration while supine on a bed, suddenly opened her eyes, looked forward and cried out that there was a horse in the room biting her. She quite precisely indicated the place in the room from which she saw the horse. Sometimes she was detached in accounting her experience, sometimes she appeared scared and tried to get off the bed and walk around the room. When the nursing and medical staff stood in front of her in the place where she had indicated the presence of the horse, she became hesitant and dubious, and in the end she interpreted what she had seen as a dream”. The episode lasted about 45 minutes. EEG findings prior to the hallucination burst were characterized by fluctuations between wakefulness and sleep (decrease in amplitude of alpha and appearance of frequencies in the theta range on the occipital regions, slowing of theta at 6-7 Hz on frontal regions; with a partial or inverted response to the opening/closure of the eyes. Shortly before the occurrence of the hallucinatory state the recording had the characteristics of the B sleep pattern according to Dement and Kleitman . Unfortunately during the episode EEG was masked by artefacts produced by the movements of the patient. The visual nature, the vivid character, the sudden onset and complete reversibility of the hallucinations and the EEG recordings , in particular the occurrence of B sleep pattern, convinced Berlucchi and Pinelli that dissociated sleep, i.e. dreams, which intrude into wakefulness, can occur in post-encephalitic parkinsonism and for extension in other cases of Parkinson’s disease.
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