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1
Therapy Optimization for Traumatic Brain Injury
James McNames, PhD Associate Professor of
Electrical and Computer Engineering Director of
the Biomedical Signal Processing Laboratory
(bsp.pdx.edu)
Traumatic brain injury (TBI) is the leading cause
of death and disability in children causing, more
than 50 of all childhood deaths. Each year, more
than 150,000 pediatric brain injuries result in
about 7,000 deaths and 29,000 children with new,
permanent disabilities. Compared to adults with
TBI, the long-term complications of TBI are often
more devastating in children due to their age and
developmental potential. Costs of pediatric TBI
in the USA alone exceed 12 billion dollars
annually. Leading causes of TBI include motor
vehicle accidents, bicycle accidents, falls, and
child abuse.

• The mission of the BSP laboratory is to advance
  the art and science of extracting clinically
  significant information from physiologic signals.
  The objectives for this research program are to
• Develop new methods of signal processing that
  extract useful information from physiologic
  signals.
• Advance our knowledge of pathophysiology through
  the investigation of behavior manifest in
  physiologic signals.
• Ground students with a solid foundation in
  statistics, signal processing, algorithm design,
  and algorithm assessment and provide them with
  the opportunity to experience the process of
  knowledge discovery, apply research methodology,
  disseminate knowledge, and learn the standards of
  peer review.
• Contribute to the regional needs of Portland and
  Oregon.
• We primarily focus on clinical projects in which
  the extracted information can help physicians
  make better critical decisions and improve
  patient outcome. We collaborate closely with
  Oregon Health \ Science University (OHSU),
  located less than 2 miles from Portland State
  University. The laboratory currently includes
  four PSU faculty members, six faculty at OHSU,
  and seven student members. James McNames,
  associate professor of Electrical and Computer
  Engineering, is the laboratory director.
• In 2004 alone we published 3 abstracts, 15
  conference papers, 2 journal articles, and 2 book
  chapters. We have many research projects underway
  in areas ranging from traumatic brain injury to
  acupuncture. Here we give brief summaries of two
  of our current research projects.

In a 3-year project sponsored by the Thrasher
Research Fund, we are developing a mathematical
model of intracranial pressure (ICP) dynamics
that extends current research models by
incorporating physiologic data from actual
pediatric TBI patients based on prospective data
collected under controlled conditions by the
Complex Systems Laboratory at OHSU. This project
will develop a clinically useful model of ICP
that can be used to help guide and predict the
response to treatment in severe TBI. This
represents a significant advance in the treatment
of children with TBI and will serve as a basis
for many additional research projects that
incorporate clinical medicine, physiology,
biomedical engineering and mathematics in a
multi-disciplinary approach towards understanding
and treating human disease.
Microelectrode Recording Analysis for
Stereotactic Neurosurgery
Parkinson's disease (PD) is the second most
prevalent neurodegenerative disease, affecting
over 500,000 people in U.S.A. and about 45 of
people over 85. Stereotactic neurosurgery is
often used for patients whose condition has
deteriorated and/or who are no longer responsive
to drug therapy. One of the critical challenges
to neurosurgeons who perform stereotactic
neurosurgery in PD patients is locating the
target structure within the brain. Current
stereotactic methods for selecting the nominal
target location use magnetic resonance imaging
(MRI) with a stereotactic frame secured to the
patient's head such that both the anatomic target
and fiducial indicators on the frame can be
visualized and registered in an image-processing
workstation. However, insufficient image
resolution (caused by small mechanical movements
of the frame, image distortion, and shifting of
the brain within the cranium) prevents precise
localization of target structures.
Figure 1. Example of microelectrode recording
(MER) visualization of a patient with Parkinson's
disease. A. Current visualization technique. The
distinction between different brain structures
is difficult to discern and only a few recording
segments can be shown simultaneously. B.
Anatomical map (Sagittal plane 12) corresponding
to the assumed trajectory path with one of our
visualization methods overlayed. C. Statistical
properties of microelectrode recordings versus
electrode depth. Our visualization clearly shows
the boundaries of the target structure (STN)
between 26 and 30 mm with the center at
approximately 28 mm
As a consequence, most neurosurgeons use
microelectrode recordings (MER) to locate the
target with better precision. The neurosurgeon
analyzes the MER signals by examining the
time-domain behavior of the signal (Figure 1A) on
an oscilloscope (or equivalent) while listening
to the signal through conventional speakers.
Although modern surgical workstations provide
some tools for MER analysis, the techniques are
cumbersome, difficult to interpret, require
manual tuning, and require the neurosurgeon to
mentally keep track of how the recordings change
as the microelectrode moves through different
brain structures. We are currently developing
new analysis methods for extracellular
microelectrode recordings (MER) that permit
researchers to visualize how the patterns of
neural activity vary spatially and between
structures within brain tissue (Figure 1C). These
methods will help neurosurgeons locate target
structures within the brain during stereotactic
neurosurgery for the treatment of Parkinson's
disease and other movement disorders. These
methods will enable neurosurgeons to locate
target nuclei more accurately, faster, and with
less training.