Wearable MEG - Using novel technology to improve surgery outcome in epilepsy patients

For patients with focal refractory epilepsy, seizure freedom can be achieved
through epilepsy surgery by removal of the epileptogenic zone (EZ). This
requires the delineation of the EZ during the pre-surgical workup using
non-invasive techniques such as Magneto/Electro-encephalography (MEG/EEG), or
invasive recordings using intracranial electrodes (dEEG). The success of the
pre-surgical workup, and thereby surgery, should be improved since seizure
freedom is achieved in only two-thirds of the patients.
Newly developed MEG sensors, so-called Optically Pumped Magnetometers
(OPMs), provide an unprecedented opportunity for epilepsy. These sensors are
smaller, lighter, and cheaper, yet have a sensitivity that is comparable to
that of cryogen-based Superconducting Quantum Interference Devices (SQUIDs).
Importantly, they can be placed directly on the scalp, thereby improving the
sensitivity to, and localisation accuracy of, epileptiform activity. Moreover,
with a wearable OPM-based array, one could record during seizures. Together,
this will not only improve diagnosis, but also the pre-surgical workup, thereby
improving the chances of successful surgery and seizure freedom.

To demonstrate that novel MEG sensors can be used successfully in clinical
practice, and to demonstrate their effectiveness as a powerful diagnostic tool
in epilepsy.

This is primarily a feasibility study. We will employ a multiple case approach,
whereby each patient*s OPM recordings will be compared with their clinically
recorded (SQUID-based) MEG recording and their previously recorded scalp EEG or
clinically recorded dEEG.

Specific study population:
Patients with focal, drug-resistant epilepsy who undergo epilepsy surgery with
pre-operative workup that includes MEG and scalp EEG or dEEG. We need to study
this particular patient population to be able to compare the performance, and
show the benefits, of the novel sensors in epilepsy patients in a clinical
situation.
The inclusion of three patients under the age of 18 is required to demonstrate
that by using on-scalp sensors instead of the standard, adult-sized, helmet the
sensitivity to epileptiform activity increases.

Study procedures:
The SQUID-based MEG recording and dEEG have already been performed as part of
routine clinical care. Similarly, the simultaneous MEG / scalp EEG recording
has already been performed as part of another research project. The extra
burden for patients in this study would be an extra recording using the OPM
sensors. The recording protocol is identical to the one they have already
undergone for the routine clinical MEG scan, with the exception that they now
wear a modified EEG cap with the OPMs attached.

Risks:
MEG is a save, non-invasive, recording technique of brain signals. The use of
OPMs has negligible risks. There is a risk of a seizure during scanning but
this should not expose the patient to any greater risk of injury than what
would be experienced in their everyday lives.

Burden:
Patients will have to travel to the VU University Medical Center in Amsterdam.
The recording will take place in a magnetically shielded room (which is about
the size of a large freight elevator), which may cause claustrophobia. They
will wear a modified EEG cap with the OPMs attached. The recording will take a
maximum of 2 hours, with breaks every 10-15 minutes. As is standard procedure
for the clinical MEG recording, patients will be sleep-deprived to increase the
chances that epileptiform activity occurs. One patient will be asked to undergo
an extended (maximal 8 hours) recording in order to capture ictal activity,
with breaks every 10-15 minutes and longer breaks of 30 minutes every 2 hours
(during which the patient can leave the scanner).

Benefits:
The OPM recordings will be evaluated for epileptiform activity. If epileptiform
activity is seen at locations not previously seen in the existing MEG data
and/or dEEG/EEG data, then this information will be reported to the treating
neurologist.