Cyclic alternating pattern as a provocative factor in nocturnal paroxysmal dystonia

PURPOSE

We made a polygraphic study of 6 patients with nocturnal paroxysmal dystonia (NPD) in which the cyclic alternating pattern (CAP) parameters were compared with those of a group of age- and sex-matched controls.

METHODS

All patients met the requirements for NPD diagnosis, characterized by generalized stereotyped movements (dystonic-dyskinetic), with a 1-min centered duration but with no clear evidence of epileptic abnormalities in the waking EEG and during nocturnal recordings.

RESULTS

Besides the major events, the NPD polysomnograms also showed shorter, repeated episodes of shorter duration (generally <20 s) consisting of abrupt movements involving one or more body segments. Overall, the motor events in patients with NPD were closely related to periods of unstable non-REM (NREM) sleep, as evidenced by the sequences of CAP, and began during an A phase. According to the conventional scoring parameters, NPD and controls differed only in sleep latency (+14 min in the NPD patients: p < 0.04). However, the architecture of sleep in the group with NPD was characterized by prolonged and irregular NREM/REM cycles. In addition, the NPD recordings showed significantly higher values of CAP rate (p < 0.0001). When major motor attacks were suppressed by medication, sleep was characterized by a decrease in the excessive amounts of CAP rate and by a more regular architecture.

CONCLUSIONS

The modulatory role of CAP on nocturnal motor events is reported.

The Stereotyped Behavior Scale for adolescents and adults with mental retardation

The development of the Stereotyped Behavior Scale for adolescents and adults with mental retardation was described. Service provider staff in three states selected 600 clients known for stereotypic behaviors and then used 66 items to rate the frequency of occurrence of these behaviors. Items with test-retest reliability less than .45 and/or interrater agreement less than .30 were deleted. The remaining 30 items were subjected to a principal component analysis with varimax rotation. A single-factor solution emerged, which explained 24.9% of the variance. After eliminating 4 items with low factor loadings, we found that the final 26-item Stereotyped Behavior Scale had an internal consistency alpha of .88, test-retest reliability was pI = .90, and interrater reliability was pI = .76.