Sleep disorders and extrapyramidal diseases: an historical review.

BACKGROUND AND PURPOSE: 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. PATIENTS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Relationship between Delta, Sigma, Beta, and Gamma EEG bands at REM sleep onset and REM sleep end.

OBJECTIVE: The aim of the present study was to analyze in detail the relationship of two newly introduced measures, related to the Beta and Gamma EEG bands during REM sleep, with Delta and Sigma activity at REM sleep onset and REM sleep end, in order to understand their eventual role in the sleep modulation mechanism. METHODS: For this purpose, power spectra of 1 EEG channel (C4, referred to A1) were obtained by means of the fast Fourier transform and the power of the bands ranging 0.75-4.50 Hz (Delta), 4.75-7.75 (Theta), 8.00-12.25 (Alpha), 12.50-15.00 (Sigma), 15.25-24.75 (Beta), 25.00-34.75 (Gamma 1), and 35.00-44.75 (Gamma 2) was calculated for the whole period of analysis (7 h), in 10 healthy subjects. Additionally, two other time series were calculated: the ratio between Beta and Gamma2, and between Gamma1 and Gamma2 (Beta and Gamma ratios). For each subject, we extracted 3 epochs of 30 min corresponding to the 15 min preceding and the 15 min following the onset of the first 3 REM episodes. Data were then averaged in order to obtain group mean values and standard deviation. The same process was applied to the 30-min epochs around REM sleep end. RESULTS: The course of the Delta band around REM sleep onset was found to be characterized by a first phase of slow decline lasting from the beginning of our window up to a few seconds before REM onset; this phase was followed by a sudden, short decrease centered around REM onset, lasting for approximately 1.5-2 min. At the end of this phase, the Delta band reached its lowest values and remained stable up to the end of the time window. The Sigma band showed a similar course with stable values before and after REM sleep onset. The Beta and Gamma ratios also showed a 3-phase course; the first phase, in this case, was characterized by stable low values, from the beginning of our window up to approximately 5 min before REM onset. The following second phase was characterized by an increase which reached its maximum shortly after REM sleep onset (approximately 1 min). In the last phase, both Beta and Gamma ratios showed stable high values, up to the end of our time window. At REM sleep end, the Delta band only showed a very small gradual increase, the Sigma band presented a more evident gradual increase; on the contrary, both Beta and Gamma ratios showed a small gradual decrease. CONCLUSIONS: The results of the present study show a different time synchronization of the changes in the Delta band and in Beta and Gamma ratios, at around REM sleep onset, and seem to suggest that the oscillations of these parameters might be modulated by mechanisms more complex than a simple reciprocity. All these considerations point to the fact that REM sleep can be considered as a complex phenomenon and the analysis of high-frequency EEG bands and of our Beta and Gamma ratios represent an additional important element to include in the study of this sleep stage.

Sleep and sleep deprivation as EEG activating methods.

OBJECTIVES: We examined retrospectively 19 patients with a history of clinical seizures, but normal activity or unclear epileptiform abnormalities in wake EEG recordings and obtained preliminary data for a controlled cohort study to evaluate the effects of sleep deprivation (SD) on interictal epileptic activity. METHODS: Nineteen patients referred to our EEG department for diagnostic or follow-up purposes were divided in two groups on the basis of the different EEG protocols applied. The first group (n=5) underwent two laboratory polysomnographies during afternoon naps, after SD, but the patients failed to fall asleep in one of the two occasions. The second group (n=14) was submitted to two polysomnographies, the first without SD and the second after SD. RESULTS: The first group of patients demonstrated focal epileptic discharges in 4 patients in which wake after SD appeared to be less activated that sleep after SD. In the second group the results obtained from the waking part of the recordings suggest a lack of activating effect due to SD. CONCLUSIONS: SD does not seem to offer greater activation than sleep alone. However, a mild SD may be a convenient activating method for inducing sleep and drowsiness without using any drug.

Median nerve F-wave study derived by flexor carpi radialis.

F-responses are produced by the antidromic activation of a limited number of motoneurones and its study can be used as a diagnostic criteria in cervical radiculopathies. Usually ulnar nerve stimulation (hypothenar derivation) and median nerve stimulation (thenar derivation) is used, so providing information mainly about 8th cervical root and 1st thoracic root. The authors describe a method for studying F-wave by median nerve stimulation and flexor carpi radialis derivation to evaluate C6-C7 roots. F-waves were clearly individuated in 47 normal subjects (94 nerves) aged from 21 to 59. Latency range was 18.0-24.0 msec, mean 21.4 +/- 1.48 (2 SD). The results of the test applied on 6 paradigmatic cases of C6-C7 radiculopathy are reported.