Thymatron
®
System IV Instructions for Use
46
reflects EEG seizure termination, as determined by the Thymatron® System IV.
Wait several seconds before
pressing the “START/STOP” button to terminate recording because the computer takes that long to process and
report the seizure endpoints and indices.
ENDPOINTS AND INDICES
A unique feature of the Thymatron® System IV, (U.S. patents: 4873981, 4878498, 5269302 and 5871517),
provides two computer-determined estimates of the duration of the induced seizure, derived from the EEG and
EMG data.
Automatic EEG Seizure Endpoint Determination
The Thymatron® System IV continuously monitors the EEG for the endpoint of seizure activity and prints the
EEG seizure duration, in seconds, on the end-of-treatment report
, provided the baseline EEG collection
procedures have been properly followed and the “READY” message has appeared. (If the treatment stimulus
is administered before the “READY” message appears, automatic EEG analysis will not occur, and the end-
of-treatment report will state the message
“Baseline not available.”
)
In about 10-20% of ECT treatments, the EEG endpoint is not readily determined (Abrams, 1997). This typically
occurs when paroxysmal activity decreases too gradually to provide a clear visual endpoint, or when the
immediate post-seizure EEG contains high amplitude activity. In these circumstances, inability to detect a
precise EEG endpoint is expected with any method of examination. The Ictal Line™ might show an on-again-
off-again broken line pattern, and the end-of-treatment report might state: “EEG Endpoint is not detected”.
Automatic EMG (Motor) Seizure Endpoint Determination
The Thymatron® System IV is shipped with the EMG monitor enabled in channel 3. When EMG monitoring
electrodes have been properly applied, the lead-wires and monitoring cable connected, then EMG tracing
automatically appears on the paper record after the treatment stimulus ends.
The Thymatron® System IV continuously monitors the EMG for motor seizure activity and prints the EMG
endpoint seizure duration in seconds, on the end-of-treatment report. Baseline EMG collection is neither
required, nor possible, in obtaining this measure.
