The usefulness of nap sleep recording during routine electroencephalography : an audit study

Abstract EN

Objectives: A measure to increase the electroencephalogram (EE G) outcome includes a short period of nap sleep during a routine standard EE G with the aim of increasing its sensitivity to interictal abnormalities or provoking seizures.

As part of an ongoing auditing of our EE G data, we aimed to investigate the contribution of nap sleep during routine outpatient department based EE Gs requested for a variety of reasons.

Methods: EE G data at the Department of Clinical Physiology at Sultan Qaboos University Hospital, Oman, from July 2006 to December 2007 and from January 2009 to December 2010 (total 42 months) were reviewed.

The EE Gs were for patients older than 13-years referred for possible epilepsy, blackouts, headache, head trauma, and other non-specified attacks.

The recording period was between 20 to 40 minutes.

Abnormalities were identified during waking and nap sleep periods.

Results: A total of 2 547 EE Gs were reviewed and 744 were abnormal (29.2%).

Of those abnormal EE Gs, nap sleep was obtained in 258 (34.7%) EE Gs, and 39 (15.1%) showed abnormalities during nap sleep.

Nineteen out of the 39 (48.7%) EE Gs were abnormal during awake and nap sleep; and 20 (51.3%) were abnormal during nap sleep, which represented only 2.7% of the total abnormal EE Gs (n = 744).

Conclusions: The contribution of the short nap sleep to the pickup rate of interictal abnormalities in EE G was minimal.

We recommend the EE G service to include one cycle of spontaneous sleep EE G directed at patients with a history suggestive of epilepsy if their awake EE Gs are normal.