Tuesday, 6 March 2001 22:19 (ET)
BAGNOLET, France, March 6 (UPI) -- French researchers say pressure waves might explain
some of the neurological mysteries that follow traumatic brain injury, including why
initial, transient loss of consciousness is the most common post-traumatic neurological
symptom.
The "stereotactical phenomenon" also explains why most TBI patients have no
focal neurological deficits such as motor, sensual or visual impairment, according to
scientists at Neurostaff, a nonprofit organization dedicated to research into the
biomechanics of brain injury.
In the United States, someone suffers a traumatic brain injury every 15 seconds. Vehicle
crashes, falls and sports injuries are the three leading causes and injuries can cause
either temporary or permanent cognitive and emotional dysfunction. Problems include memory
loss, speech impairment, fatigue and impulsive behavior, according to the Brain Injury
Association, in Alexandria, Va.
The stereotactical theory considers the spherical shape of the skull-brain interface,
together with the series of interactions that take place between the skull and the brain
during acceleration -- both linear and rotational --and impact. Secondary vibrations with
spherical wave fronts created by the skull brain interaction create secondary pressure
waves that can penetrate deep into the brain, said Neurostaff director Dr. Catalin Obreja.
These accelerating waves, which resemble bicycle wheel spokes, increase in size as they
travel away from the skull, with their pressure becoming greatest when it reaches the
center of the brain. The spatial distribution of this pressure gradient is responsible for
deep cerebral lesions, the main cause of concussion and other common neurological symptoms
of head trauma, the researchers said.
"Classical theories in this field date since about 40 years ago, long before the CT
and MRI, and cannot explain the clinical observations we can see using these
instruments," said Dr. Obreja. "The stereotactical theory is complementary to
the classical theories while explaining common posttraumatic signs and lesions."
"In our opinion this new approach will have major impact on the TBI models' used in
the pharmacological research," she said. "To our best knowledge, this is the
first theory to explain these clinical phenomena."
According to Dr. Obreja, functional recovery is faster for the brain's neuronal circuits
with fewer infrastructure lesions.
"If the superficial lesions were more important than the deeper ones, the recovery of
the focal deficits would be longer than recovery of consciousness, not the other way
around," she explained. "The stereotactical phenomena also explains the high
incidence of memory disturbance after traumatic head injury."
Dr. William Heetderks, program director in brain repair and plasticity at the National
Institute of Neurological Diseases and Stroke, told United Press International that while
the Neurostaff research is intriguing, the phenomenon they describe needs further study.
"Their argument is that a pressure wave travels through the brain after a head injury
much like pressure waves move through a fluid," he said "Conceptually it's
possible. Because the brain is spherical, pressure waves are greatest when they reach the
center of the brain. But it falls more into the category of a theory rather than a
phenomenon, and it needs to be tested further in experimental models. It's
plausible, but it needs more study."
More than one million Americans are treated for traumatic head injuries each year and TBI
is the primary cause of death for patients under age 45, according to the Brain Injury
Association. Brain damage can be focal, confined to one area of the brain, or diffuse,
involving more than one area of the brain. The severity of a TBI can range from a mild
concussion to the extremes of coma or even death, and symptoms can include headache,
nausea, confusion or other cognitive problems, a change in personality, depression,
irritability, and other emotional and behavioral problems.
Phineas Gage is probably the most famous patient to have survived severe brain damage. In
September 1848, a dynamite charge he had set exploded prematurely and blew a tamping iron
through his head. The tamping iron was 3 feet 7 inches long and weighed 13 1/2 pounds.
Gage was knocked over but never lost consciousness, even though most of the front part of
the left side of his brain was destroyed. Some months after the accident Gage felt strong
enough to resume work, but because his personality had changed radically -- the once
agreeable man had become a troublemaker -- his employers would not take him back.
(Reported by UPI Medical Writer Kurt Samson in Washington)
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Copyright 2001 by United Press International.