ACCP-SEEK Board Review Question of the Month |

Abnormal Finding in an Overnight Sleep Study* FREE TO VIEW

Susan M. Harding, MD, FCCP
Author and Funding Information

*From the ACCP-SEEK program, reprinted with permission. Items are selected by Department Editors Richard S. Irwin, MD, FCCP, and John G. Weg, MD, FCCP. For additional information about the ACCP-SEEK program, call 1-847-498-1400.

Correspondence to: Susan M. Harding, MD, FCCP, Department of Pulmonary/CCM-THT Room 215, University of Alabama at Birmingham, 1900 University Blvd, Birmingham, AL 35294-0015

Chest. 2000;118(6):1817-1818. doi:10.1378/chest.118.6.1817
Text Size: A A A
Published online

The accompanying Figure 1 is a montage from an overnight sleep study in which each vertical dotted line represents a 30-s epoch. Which of the following is the most likely cause of the findings displayed with arrows in the right and left leg electromyograms (EMGs)?

A. Arousals from obstructive sleep apneas

B. Periodic limb movements of sleep

C. Nocturnal leg cramps

D. Arousals from obstructive sleep hypopneas

E. Artifact

Answer: D. Arousals from obstructive sleep hypopneas

This 3-min recording from an overnight polysomnogram shows repetitive obstructive sleep hypopneas causing arousals and oxygen desaturations. There is a reduction of nasal and oral airflow > 50% of baseline amplitude that is associated with continued thoracic respiratory effort. The increases in both left and right leg EMGs are at the termination of hypopneas. Hypopneas are characterized by a recognizable reduction, but not complete cessation, of airflow.

These events are not apneas, because there is no total cessation of airflow. Periodic limb movements of sleep are stereotypic periodic movements of the legs or arms. Usually these movements include dorsiflexions of the ankles and toes, which are slower than myoclonic jerks. Polysomnographic features of periodic limb movements of sleep include increased EMG activity lasting 0.5 to 5.0 s, at intervals between 20 s and 40 s, independent of other associated events. Nocturnal leg cramps produce increases in the EMG signal lasting much longer than those of periodic limb movements of sleep. Artifacts present on this recording include the ECG artifact in the electro-oculogram and ECG leads. However, the artifact is not responsible for the electromyographic findings.

O’Keefe ST. Restless leg syndrome: a review. Arch Intern Med 1996; 156:243–248

Phillips BA, Anstead MI, Gottlieb DJ. Monitoring sleep and breathing: methodology. Part I: Monitoring breathing. Clin Chest Med 1998; 19:203–212

Recording and scoring leg movements: The Atlas Task Force. Sleep 1993; 16:748–759

Dr. Harding is supported in part by an NIH-NHLBI Sleep Academic Award, Grant HL-03633.

Figure Jump LinkFigure 1. Overnight polysomnogram results.Grahic Jump Location


Figure Jump LinkFigure 1. Overnight polysomnogram results.Grahic Jump Location



Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Find Similar Articles
CHEST Journal Articles
PubMed Articles
OS 35-01 THE PREVALENCE OF SLEEP APNEA SYNDROME IN PRIMARY ALDOSTERONISM. J Hypertens 2016;34 Suppl 1 - ISH 2016 Abstract Book():e399.
HW 03-2 EFFECT OF CPAP ON THE TREATMENT OF RESISTANT HYPERTENSION. J Hypertens 2016;34 Suppl 1 - ISH 2016 Abstract Book():e538.
  • CHEST Journal
    Print ISSN: 0012-3692
    Online ISSN: 1931-3543