ABSTRACT
We report a case of misinterpretation of sleep-disordered breathing due to periodic
limb movement disorder. A 67-year-old man was diagnosed with sleep-disordered breathing
and subsequently placed on treatment with nasal continuous positive airway pressure
(CPAP). The initial diagnostic evaluation did not include measurement of anterior
tibialis electromyogram. The respiratory disturbance index of the initial evaluation
was 23. After a brief period of nasal CPAP use, the patient discontinued the treatment
because no significant change in daytime alertness was noted and signs of CPAP-related
insomnia appeared.
The patient was restudied polysomnographically with monitoring of anterior tibialis
electromyograms. This study identified 392 leg movements of which 65% were associated
with brief EEG arousal from sleep.
Double-blind analysis of respiratory disturbance and leg movements yielded a total
number of 360 arousals in the overnight recording. Eighty-five percent of all respiratory
events could be associated with central hypoventilation following periodic limb movement-associated
EEG arousal. No significant hypoxia was recorded with these events.
We hypothesize that chemoreceptor stimulation secondary to EEG arousal during sleep
is responsible for this central hypoventilation.
This case report highlights that recording and scoring of leg movements must be an
integral part of polysomnographic evaluations.
KEYWORD
Sleep - sleep apnea - periodic limb movement disorder - polysomnography - instrumentation
