Electroencephalographic examination of epileptic dogs under propofol restraint

Abstract

The main aim of this study was to identify interictal epileptiform discharges in a group of dogs with seizures of known aetiology (symptomatic epilepsy, SE) and in dogs with idiopathic epilepsy (IE). Propofol was used for chemical restraint in all dogs. We found electroencephalographic (EEG) changes that could be considered epileptiform discharges (EDs) in 5 out of 40 dogs (12.5%). The EEG changes identified were spikes in four cases and periodic epileptiform discharges in one case. All EDs were seen in the SE group. We conclude that the interictal electroencephalographic examinations of propofolanaesthetised dogs suffering from IE and SE rarely show epileptic discharges and that the diagnostic value of such EEGs in the work-up for epilepsy seems to be low as epileptic discharges were unlikely to be detected. However, positive findings are more likely to be connected with SE. We found frequent, transient EEG phenomena (spindles, K-complexes, vertex waves, positive occipital sharp transients of sleep, cyclic alternating patterns), which are non-epileptic but their differentiation from epileptic phenomena is challenging.

EEG Transients in the Sigma Range During non-REM Sleep Predict Learning in Dogs

“…In addition, we also repeated each search with one harmonic below and above the target frequency to ensure any effect discovered with that target was not due to random noise or spectrally similar, sharp-wave, epileptoform activity. Three automated criteria were then used to determine if a time-window was occupied by a spindle: The maximum peak power of a given segment was within the target range 53 (12–14 Hz 6 , 9–16 Hz 18 , 5–12 Hz 1 respectively). Amplitudes were calculated for each window as the root mean square (rms) of the corresponding signal segment 53 .…”

“…The maximum peak power of a given segment was within the target range 53 (12–14 Hz 6 , 9–16 Hz 18 , 5–12 Hz 1 respectively).…”

“…Studies relying on electroencephalography (EEG) to study the canine brain have so far focused on large-scale neural dysfunctions like epilepsy 1 , 2 or oscillations signalling levels of attention, vigilance or sleep 3 – 5 . Yet in order to refine the level of detail and to extract more information, research needs to focus on EEG transients – short latency signatures of functional events – such as sleep spindles.…”

“…Our version of the algorithm was tested with three different frequency definitions, corresponding to the strict 12–14 Hz range 6 , 53 , the broader 9–16 Hz range 18 and a 5–12 Hz range proposed specifically for dogs by Pákozdy et al . 1 . The latter was derived from an explorative, visual inspection of the EEG transients.…”

Relationship between interictal epileptiform discharges under medetomidine sedation and clinical seizures in canine idiopathic epilepsy

“…When limited to ED with amplitude of at least 50 μV, 76 per cent of epileptic dogs had ED. The reported detection rates of ED in epileptic dogs varied from 12.5 per cent to 84 per cent 13 15 22 24–26. The reasons for this variation may be due to differences in seizure severity in the dogs studied, recording duration, electrode settings, activation techniques or the definition of pathological ED to be included.…”