D J Koffler | Search PubMed

PubMed1989

Interictal spiking increases after seizures but does not after decrease in medication.

In patients with focal epilepsy, EEG spike rate fluctuates considerably over time. We had previously shown that seizure occurrence played an important role in these fluctuations. We undertook this study to confirm this finding with better control of critical variables such as state of alertness and spike quantification, and to assess the spatial extent of the changes. Background activity changes and antiepileptic drug levels were also examined in relation to spiking. Spike discharge rate increased in the hours and days following seizures in widespread brain regions including, but not restricted to, the seizure focus. Spike rate did not change systematically before seizures. Postictal changes in background activity did not parallel spike fluctuations. Decreased antiepileptic drug levels did not cause increased spike rate. These results indicate that, following seizures, there is activation of interictal spiking which is not paralleled by changes in background activity. It is most often widespread and not necessarily most prominent at the site of seizure onset.

Adult↗

PubMed1985

Automatic detection of spike-and-wave bursts in ambulatory EEG recordings.

The spike-and-wave detection scheme described in this report is based on the recognition of groups of spikes and sharp waves with loosely defined temporal and inter-channel relationships; presence of a slow wave is required only with spikes of low amplitude. Particular attention is paid to artefacts. This method allows the detection of classical 3/sec spike-and-wave activity as well as irregular patterns. The analysis produces a standard EEG tracing containing only the detected bursts, allowing conventional visual examination by an electroencephalographer. After interactive editing of false detections, a quantitative display of burst distribution can be obtained. The rate of false detections due to artefacts or non-epileptiform patterns was evaluated on eight 20 h cassette recordings; an average of 2.4-10 false detections were made per hour. When tested against hand-scoring by two EEGers of eight 2 h recordings which included very irregular spike-and-wave patterns, the computer detected 70% of the spike-and-wave activity identified by both readers (i.e., 30% false negatives), while 12% of the computer detections were not identified by either reader (false positives). The context in which such a computer method with imperfect performance can be clinically useful is discussed.

Adolescent↗