my personal edition > fibromyalgia > news


  E-Mail this DGReview to a colleague

DGReview

Cyclic Alternating Pattern Correlated to Severity of Symptoms in Fibromyalgia

The increase of cyclic alternating pattern rate indicates a poorer quality of sleep in patients with fibromyalgia and is strongly correlated to the severity of symptoms, according to a recent study by an Italian team of researchers.

Cyclic alternating pattern (CAP) corresponds to a prolonged oscillation of the arousal level between 2 reciprocal functional states termed phase A (greater arousal) and phase B (lesser arousal).

"In the dynamic organisation of sleep, CAP expresses a condition of instability of the level of vigilance that manifests the brain's fatigue in preserving and regulating the macrostructure of sleep," explains Maurizio Rizzi, MD, Centre for Sleep and Respiratory Disorders, Milan, Italy.

Dr Rizzi and colleagues evaluated the presence of cyclic alternating pattern in 45 consecutive Caucasian patients (42 women, age 52.2 ± 8.2 years) with fibromyalgia and in 38 healthy controls matched for age, sex and body mass index.

A sleep questionnaire evaluated sleep complaints and the Epworth Sleepiness scale (ESS) measured the general level of daytime sleepiness. Polysomnography was performed in the sleep laboratory, and airflow, ventilatory efforts, oxyhaemoglobin saturation were recorded.

Correlation between sleep, breathing and body position was analysed automatically by a computer. Through computer analysis, the investigators were able to determine the sleep histogram of each patient and to identify the sequences of the periods corresponding to the CAP and to periodic breathing.

Patients with fibromyalgia complained of: nocturnal awakening (100%), chronically poor sleep (90%), morning headache and sensation of waking unrefreshed (85%). They had lower sleep efficiency (sleep time/time in bed) than controls (P < .01) and twice as many arousals per hour of sleep (P < .01).

The CAP rate was significantly increased in patients with fibromyalgia compared to controls (P < .001). The mean duration of phase A and phase B were also increased (P < .001 in all cases).

The CAP rate correlated negatively with sleep efficiency (P <.001) and positively with the severity of fibromyalgia clinical symptoms (tender point index: P < .001), the duration of fibromyalgia in years (P < .05), the ESS score (P < .01) and the periodic breathing as a percentage of sleep time (P < .01).

"Our data confirm that the nonrestorative sleep of patients with FM is not related to a marked disruption of sleep architecture; FM patients may be more easily arousable and have less slow-wave sleep because of the exacerbation of pain," the authors concluded. "It is, however, closely related to serious alteration of the microstructure of sleep, as shown by the 29% increase of the CAP rate in the FM patients in comparison to controls".

J Rheumatol 2004 Jun;31:6:1193-9 "Cyclic alternating pattern: a new marker of sleep alteration in patients with fibromyalgia?"

E-Mail this DGReview to a colleague

To print, use this version