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Real-time Brain Mapping Technology shows
potential for improving Epilepsy and Brain
Tumor Patient Outcome
Newswise — Epilepsy and seizures affect
nearly 3 million Americans of all ages, with
200,000 new cases of seizures and epilepsy
occurring each year.
Epilepsy surgery may be performed in
patients who have seizures associated with
structural brain abnormalities, such as
benign brain tumors and cortical dysplasia,
malformations of blood vessels, the genetic
disorder tuberous sclerosis, and strokes.
The goal of epilepsy surgery is to identify
an abnormal area of brain cortex from which
the seizures originate and remove it without
causing any major functional impairment.
In the U.S., it is estimated that in 2009,
there were a total of 22,070 new cases of
brain and other CNS tumors diagnosed.
Gliomas account for 40 percent of all tumors
and 78 percent of malignant tumors. In brain
tumor surgery, the aim is always to maximize
the resection while minimizing the loss of
Malignant gliomas usually occupy, or are
continuous with functional brain tissue,
making them difficult to completely resect.
The need to preserve functions like language
and movement must be balanced with the
necessity for maximal tumor resection.
The gold-standard method of determining
cortical functional in brain surgery has
been electrocortical stimulation (ECS). ECS
works by disrupting the normal cortical
function to evoke movement or create
transient functional disruption.
Researchers at the University of Washington,
Seattle, explored the role of broadband
electrocorticographic measurement, with the
goal of improving the efficacy of brain
The results of this study, Real-Time
Electrocorticographic Mapping of Eloquent
Cortex, were presented by Kai Miller, PhD,
May 3, 2010, during the 78th Annual
Meeting of the American Association of
Neurological Surgeons in Philadelphia.
Co-authors are Adam O. Hebb, MD, and Jeffrey
G. Ojemann, MD.
Electrocorticographic (ECoG) recordings were
produced using subdural electrodes and
SynAmps2 amplifiers, set to sample at 1 kHz
and band-pass filter from 0.15 to 200 Hz.
Data were collected and processed online at
the bedside using software on a laptop
A total of 11 patients with epilepsy,
awaiting brain surgery, were enrolled in
The efficacy of simple integration of
“chi-band” (76-200Hz) change in the ECoG
signal was analyzed by implementing a simple
band-pass filter, to estimate broadband
Following a brief (less than 10-second)
period to characterize baseline activity,
chi-band activity was integrated while the
patients performed motor movement commands
and/or verb-generation testing.
For the motor movements testing, each
patient performed repeated opening and
closing of the hand for 3-second periods,
alternating with equal periods of rest.
Each period was visually cued, for both
movement and rest periods. The hand movement
was repeated 30 times, but only the first 5
or 15 seconds of movement was used for this
During simple hand movement, primary hand
motor areas were clearly identified.
Patients were asked to state verbs in
response to nouns that were presented. The
exercises spanned 15 to 30 seconds, during
which time, brain mapping took place.
While performing verb generation, primary
mouth motor areas were consistently
identified, as were areas consistent with
Broca’s and auditory speech.
“Our findings were substantiated by ECS in
the same patients. Broadband ECoG changes
can be captured in real time to identify
“This study demonstrates the existence of a
powerful new tool for functional brain
mapping in the operative and chronic implant
setting and warrants further testing,”
remarked Dr. Miller.
Founded in 1931 as the Harvey Cushing
Society, the American Association of
Neurological Surgeons (AANS) is a scientific
and educational association with more than
7,600 members worldwide.
The AANS is dedicated to advancing the
specialty of neurological surgery in order
to provide the highest quality of
neurosurgical care to the public. All active
members of the AANS are certified by the
American Board of Neurological Surgery, the
Royal College of Physicians and Surgeons
(Neurosurgery) of Canada or the Mexican
Council of Neurological Surgery, AC.
Neurological surgery is the medical
specialty concerned with the prevention,
diagnosis, treatment and rehabilitation of
disorders that affect the entire nervous
system, including the spinal column, spinal
cord, brain and peripheral nerves.
Disclosure: the author reports no conflicts