Sleep disorders and extrapyramidal diseases: an historical review

Sleep disorders have been mentioned since the first descriptions of extrapyramidal diseases in James Parkinson's Essay on the Shaking Palsy, but only recently they have become the subject of attention, thanks to new acquisitions in clinical knowledge and electroencephalographic technology. In the late 1960s, the introduction of L-dopa permitted comparison of sleep patterns in drug-naive patients before and after therapy in conditions very similar to experimental ones. Historically, we can recognise two major lines of study, one dealing with descriptions of sleep behaviours modified by drugs and the other with polysomnographic sleep research carried out before and after treatment.

The data obtained from the first polysomnographic studies led to the definition of sleep macro- and microstructure in patients suffering from Parkinson's disease, but the interpretation of drug-induced changes was not unequivocal.

According to some authors, the improvement in sleep architecture was due mainly to improvement of nocturnal motor impairment. Other researchers suggested a primary sleep dysfunction caused by specific neurodegenerative processes in the brain structures regulating the sleep-wake cycle.

The latter hypothesis has recently been supported by the observation that distinct sleep disorders, such as REM behaviour disorder or restless legs syndrome, often herald extrapyramidal diseases or are a frequent adjunctive complaint for these patients.