CAP: A New Marker of Sleep Alteration in Patients with Fibromyalgia?

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Cyclic Alternating Pattern: A New Marker of Sleep Alteration in Patients

with Fibromyalgia?

MAURIZIO RIZZI, PIERCARLO SARZI-PUTTINI, FABIOLA ATZENI, FRANCO CAPSONI,

ARNALDO ANDREOLI, MARICA PECIS, STEFANO COLOMBO, MARIO CARRABBA, and

MARGHERITA SERGI

ABSTRACT.

Objective. In the dynamic organization of sleep, cyclic alternating

pattern (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. We evaluated the presence of CAP

in patients with fibromyalgia (FM) compared to healthy controls.

Methods. Forty-five patients with FM (42 women) were studied and

compared with 38 healthy subjects (36 women) matched for age, sex, and

body mass index. Entry criteria were diagnosis of FM according to 1990

American College of Rheumatology criteria; willingness to participate in

the study; and having no other diagnosis of autoimmune, neoplastic, or

other possible causes of secondary diffuse musculoskeletal pain.

Patients in the study underwent polysomnography recordings and a sleep

questionnaire. Hypersomnolence was evaluated according to the Epworth

Sleepiness Scale.

Results. FM patients had less sleep efficiency (sleep time/time in bed)

than controls (79 ± 10 vs 89 ± 6; p < 0.01), a higher proportion of

stage 1 non-rapid eye movement (non-REM) sleep (20 ± 5 vs 12 ± 5; p <

0.001), and twice as many arousals per hour of sleep (9.7 ± 3.3 vs 4.1 ±

1.9; p < 0.01). The CAP rate (total CAP time/non-REM sleep time) was

significantly increased in FM patients compared to controls (68 ± 6% vs

45 ± 11%; p < 0.001). CAP rate seemed to correlate with the severity of

clinical symptoms in FM patients (tender points index; p < 0.01) and

with less efficiency of sleep (p < 0.01).

Conclusion. The increase of CAP rate indicates a worse quality of sleep

in patients with FM. These data are strongly correlated to the severity

of symptoms. (J Rheumatol 2004;31:1193-9)

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Mayo Clinic in Rochester

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