Ambulatory EEG

Ambulatory EEG

Clinical Use:

	Confirm clinical diagnosis of epilepsy
	Identify interictal epileptiform activity
	Document seizures that the patient is unaware of
	Evaluate response to therapy
	Evaluate suspected pseudoseizures
	Evaluate syncope

Overall:

	6-15% of AEEGs record seizures
	34.9% of patients with known seizures had a positive ambulatory EEG
	38% of patients who were referred for AEEG had some type of epileptiform abnormality.
	prior normal or nondiagnostic routine EEG, epileptiform activity has been reported in 12-25% of AEEGs.

sleep-deprived EEG vs a computer-assisted 16-channel AEEG

	in patients with suspected epilepsy (but a nondiagnostic initial routine EEG) found that sleep-deprived EEG improved detection of epileptiform discharges by 24%, while AEEG improved detection by 33%.
	Of the 46 patients studied, 15% had actual seizures recorded on AEEG, while none had seizures during the sleep-deprived recording.

In non-epileptic patients

	spikes found on overnight AEEG in 0.7% of asymptomatic adults without history of migraine or family history of epilepsy.
	history of migraine headaches or a family history of epilepsy, the incidence of spikes in these patient groups was 12.5% and 13.3%, respectively.

Patients who are known to have epilepsy

	study of epilepsy monitoring unit patients found that 63% of all seizures were unrecognized by the patients.
	Liporace found that the AEEGs of 3/46 patients demonstrated seizures that were not designated as an event by the patient.

Pseudoseizures, also known as psychogenic seizures or nonepileptic events, are clinical events with altered movement, emotion, sensation, or experience similar to those due to epilepsy but without an electrographic ictal correlate.

	They are surprisingly frequent, occurring in up to 20% of patients at epilepsy referral centers and in 5-20% of outpatient populations.
	Estimated 10-60% of epilepsy patients have both pseudoseizures and epileptic seizures.