Hyperventilation during electroencephalography: Safety and efficacy

Abstract

HV is rarely associated with adverse events, but contributes to the diagnosis and classification of seizure disorders in an appreciable proportion of patients with epilepsy and non-epileptic attacks. These findings confirm that HV in selected patients is a valid activation technique in diagnostic EEG, where the potential benefits out weigh the risks, and also provide information that may assist the informed consent process.

Diagnostic yield of five minutes compared to three minutes hyperventilation during electroencephalography

“…This is in accordance with previous studies on the diagnostic yield of HV during EEG [2,[7][8][9][10][11].…”

“…However, this is influenced by the low percentage of patients who had seizure or IEDs only during HV [11]. If we express the difference as percentage of the total number of patients who had seizures or IEDs only during HV, the difference between 3 and 5 min HV is 16% and 30%, respectively.…”

“…In most of these studies the duration of the HV was 3 min [2,7,8], in one study it was 4 min [9], and in another study 5 min HV was performed [10]. The duration of the HV varied between 3 and 7 min in a recently published study [11].…”

Proposal for best practice in the use of video-EEG when psychogenic non-epileptic seizures are a possible diagnosis

“…Service evaluations have shown that, in patients referred for EEG with suspected PNES, 12/102 (11.8%) had a PNES elicited by hyperventilation and 15/133 (11.3%) had a PNES evoked by photic stimulation (Kane et al, 2014, Whitehead et al, 2016b). In one prospective study as many as 5/15 (33%) patients had a PNES during these activation procedures, when they were referred from a specialist outpatient clinic with probable PNES immediately after describing their symptoms to the doctor (McGonigal et al, 2002).…”

Effect of alterations in breathing patterns on EEG activity in normal human subjects

“…EEG findings in COPD patients with encephalopathy/ intellectual impairment show higher occurrence of slow wave bands and lower occurrence of beta waves predominantly in the fronto-temporal region, secondary to hypoxemia & hypercapnia (9,10). Besides, a brief period of hyperventilation is also known to influence CNS by causing generalised increase in excitability helping to reveal latent epileptic foci if any, and hence is used in diagnosis of epilepsy by provoking epileptic discharges (11).…”