Concern over chemicals brain risk

Toxic chemicals may be causing a pandemic of brain disorders because of inadequate regulation, researchers say.

A report in the Lancet identifies over 200 industrial chemicals, including metals, solvents and pesticides, which have potential to damage the brain.

Studies have shown low-level exposure of some can lead to neurobehavioral defects in children, the US and Danish team behind the report said.

UK experts remained divided over the findings.

One in six children worldwide has a development disability such as autism and cerebral palsy.

The causes are unknown, but the researchers trawled through a range of previous studies and data to show how some chemicals can effect the brain.

The team, from the University of South Denmark and New York's Mount Sinai School of Medicine, said pinning down the effects of industrial chemical pollution was extremely difficult because symptoms may not develop for several years.

The report said lead, which was used in petrol from 1960 to 1980, illustrated the risk of even low exposure of industrial chemicals for children.

Based on what is known about the toxic effects of lead, this may have reduced IQ, shortened attention span, slowed motor co-ordination and heightened aggressiveness.

The researchers said developing brains - defined as from foetus to adolescence - were much more susceptible to toxic chemicals than those of adults.

Chemicals

Several other chemicals, including methylmercury, arsenic and polychlorinated biphenyls, were also studied in depth and shown to cause neurobehavioral problems.

The scientists identified 202 industrial chemicals with the potential to damage the human brain, and said they were likely to be the "tip of a very large iceberg".

More than 1,000 chemicals are known to be neurotoxic in animals, and are also likely to be harmful to humans.

Lead researcher Dr Philippe Grandjean said: "The human brain is a precious and vulnerable organ. And because optimal brain function depends on the integrity of the organ, even limited damage may have serious consequences.

"Only a few substances, such as lead and mercury, are controlled with the purpose of protecting children.

"The 200 other chemicals that are known to be toxic to the human brain are not regulated to prevent adverse effects on the foetus or a small child."

Of the 100,000 chemicals registered for commercial use in the EU in 1981 and the 80,000 in the US, fewer than half had been subjected to even the most basic testing.

Researchers said it was only recently that the tide has started changing with the EU's Reach programme, which will lead to strict regulation of chemicals if there is an early indication of the potential for a serious toxic effect.

Professor Mark Hanson, director of developmental origins of health and disease at Southampton University, said: "The authors have put their finger on something which is important and which will not go away."

But he said the findings were extremely hard to prove as the effect of the chemicals did not seem to lead to gross abnormalities, "but rather change the way that the normal control systems work".

However, Professor Alan Boobis, a toxicology expert at Imperial College London, said: "The authors of this review have raised an issue of significant concern, but some of the evidence in support of the conclusions lacks rigour."

Concern Over Effects of Statins on Brain

Writing in the Wall Street Journal, Melinda Beck reports that at least one neurologist is concerned that statins - popular drugs used to treat high cholesterol - may be affecting the brain. Though the majority of cardiologists have not shown concern, one trial underway at the University of California San Diego is attempting to uncover what, if any, effects statins have on mood, thought processes, and behavior.

The concern arises because the protective sheaths that insulate neurons in the brain could be vulnerable to the actions of statin drugs. These myelin sheaths are composed mainly of cholesterol, which statins are designed to fight.

Critics point out both that the delicate structures of the brain are protected by the blood-brain barrier, which statins are not known to cross, and that other studies have shown that statins may actually help prevent certain neurological diseases like Alzheimer's by reducing the amount of free cholesterol in the body.

Statins are prescribed to lower bad cholesterol (LDL) and may patients with high blood pressure and high cholesterol are treated with these drugs.

Studies are ongoing.

How Do I Know if My Neurosurgeon Is Board Certified?

Board certification is an advanced credential
that indicates a high degree of competence and
training in the specialty of neurosurgery. A
neurosurgeon seeking board certification within
the American Board of Neurological Surgery
(ABNS) must submit to a rigorous evaluation
process governed by the American Board of
Medical Specialties. Before board certification
is granted a neurosurgeon must:
• Validate appropriate education and training
• Evidence professional practice skills,
judgment, and knowledge – which includes
opinions by his/her colleagues
• Pass both written and oral examinations
in their specialty
Board certification is considered the “gold
standard.” It is a way for patients to assess the
neurosurgeons they seek for treatment. You
can ensure that your neurosurgeon is board
certified by calling the American Board of
Medical Specialties at 866-275-2267, by
visiting their website (www.abms.org), or by
calling the Physician Referral Service at the
hospital where the doctor is on staff.

What Are the Common Risks of Brain Tumor Surgery?

Brain tumor surgery poses both general and
specific risks. The general risks apply to anyone
going through surgery for any reason and are not
limited to brain tumor surgery. These include:
• Infection
• Bleeding
• Blood clots
• Pneumonia
• Blood pressure instability
Risks specific to brain tumor surgery depend
greatly on the particular location of the tumor.
Particular areas of the brain control functions
such as vision, hearing, smell, movement of the
arms and legs, coordination, memory, language
skills, and other vital functions. The process of
operating on the brain always includes some risk
that nerves or blood vessels serving these areas
will be damaged. This could result in partial or
complete loss of sensation, vision, movement,
hearing or other functions. When a tumor is
located deep within the brain it increases the
risk and range of possible complications.
Additional risks, while generally rare, are also
possible. These brain surgery risks include:
• Seizures
•Weakness
• Balance/coordination difficulties
• Memory or cognitive problems
• Spinal fluid leakage
• Meningitis (infection causing inflammation of
membranes covering the brain and spinal cord)
• Brain swelling
• Stroke
• Hydrocephalus (excessive fluid in the brain)
• Coma
• Death

Microscope-Based Devices

Also used during stereotactic surgical procedures
are microscope-based devices. This technology
tracks the exact position of the operating
microscope with the fiducial markers placed on
the head, giving precise coordinates for the tumor.
Previous CT or MRI scans are superimposed
in the microscope so the neurosurgeon can see
the tumor’s image as they work.

Frameless Stereotactic Surgery

Instead of using an external frame as a reference
point, frameless stereotactic surgery uses tiny
markers, called fiducial markers, that are taped
or glued to the head before the brain is scanned.
The scan is then loaded into a planning and
navigation computer, producing a 3-dimensional
representation of the head, brain and tumor.
During surgery these markers are touched with
a pointing device, called a “Wand.” Identified
on the scan, the computer “knows” where the
surgical instrument is during the procedure in
relation to the brain and tumor.

Frame-Based Stereotactic Surgery

With frame-based stereotactic surgery, a lightweight
frame is attached to the skull at four points.
Local anesthesia is used to numb the places where
the pins contact the skull. Once the frame is
attached a CT, MRI or dye scan (angiography) is
done. Since the scan images both the tumor and
the frame, it is able to show the exact location of
the tumor in three dimensions in relation to the
head frame. The neurosurgeon takes these
coordinates and precisely inserts a probe through
a small incision in the skull to perform the biopsy
or other procedure.
It also has some limitations. The frame can
sometimes obstruct the neurosurgeon’s view of
the site; it can be time-consuming to manually
set the frame and read the scans; there is a
limited space to work within the radius of the
arc; and the scans and surgery usually need to
be performed the same day.

STEREOTACTIC SURGERY

The use of highly advanced computers to
locate and create a three-dimensional image of
a tumor is called stereotaxy. When used during
surgery, this technique is called stereotactic
surgery. Conventional x-rays can only measure
two dimensions: height and width.
Stereotaxyadds the third dimension of depth, which
enhances the neurosurgeon’s ability to precisely
map the location of the tumor and find the best
and safest pathway for removing it.
Stereotactic techniques may be used to prepare
for a surgery, during biopsy or tumor removal,
while implanting radiation pellets, or to provide
a navigation system during surgery. These
techniques are especially useful in locating and
removing tumors deep within the brain, such as
brain stem and thalamic tumors. Stereotactic
systems are used in operating rooms, enabling
surgeons to view images of the brain as surgery
is being performed.

PHOTODYNAMIC THERAPY (PDT)

Photodynamic therapy is a procedure that
involves the use of both a laser and a sensitizing
drug. Just prior to surgery, the drug is injected
into a vein or artery where it travels through the
bloodstream and is absorbed by the tumor. The
drug contains a special compound that causes
tumor cells to appear a fluorescent “glowing
green.” During surgery, the neurosurgeon aims
the laser at the tumor, which activates the drug
and kills the tumor cells.

This type of therapy does have limitations.
• Only tumors that are considered operable
can be treated with this method.
• Only tumor cells that are visible to the
neurosurgeon can be identified and treated
using the sensitizing drug. Portions of a tumor
may be hidden and not susceptible to light.
• Some tumors will not respond to the
sensitizing drug.
• Tumors near the brain stem cannot be treated
with this method due to the risk of swelling
that might occur.

NEURO-ENDOSCOPY

A neuro-endoscope, or endoscope, is a long,
narrow tube that has a camera lens and a light
source at the end. This is the same type of
equipment used to perform a colonoscopy – but
adapted for use in the brain. Neuro-endoscopes
are used to visualize hollow pathways in the
brain such as the ventricles. The endoscope is
inserted through a small hole in the skull, then
threaded into a ventricle. The endoscope
provides a lighted picture of the area as it
appears at that moment, in “real-time.” A
surgical laser can also be attached, giving the
neurosurgeon the ability to perform a biopsy
within the ventricle, to remove blockage from a
shunt, to remove tumors found in the ventricle,
and for the removal of cysts. Since this tool is long
and very narrow, an endoscope is generally not
used to remove larger tumors or tumors which
are accessible with traditional surgical tools.

MICROSURGERY

Microsurgery involves the use of a highpowered
microscope or other means of visual
magnification during surgery, and tiny surgical
tools that enable the neurosurgeon to perform
exceptionally delicate operations. Microsurgery
is used where the structures in the brain are
very small and precise movement is crucial.
This technique may be helpful in removing
tumor wrapped around blood vessels or nerves,
or along the bony ridges of the skull base.

LASERS

A laser is a surgical tool. It is a device that emits
a narrow beam of intense heat that can cut and
vaporize tissue during brain surgery.

Lasers may be especially important with tumors
located at the base of the skull, deep within the
brain, or those tumors that cannot be removed
easily for any number of reasons. Lasers are
frequently used in microsurgery, photodynamic
therapy and for a variety of diagnostic purposes.
Whether a neurosurgeon uses a laser during
surgery, or not, depends on his/her personal
judgment and the best “tools” for removal of
any given tumor.

CONVECTION ENHANCED DELIVERY ( C E D )

One of the newest methods of delivering
chemotherapy drugs or biologic therapies
to a tumor is CED, or “convection enhanced
delivery.” CED uses the principles of constant
pressure to “flow” or “infuse” substances
through brain tumor tissue. The procedure
begins with a surgery, during which a catheter
(or multiple catheters, depending on the tumor
size) is placed into the tumor area. The
neurosurgeon then connects a pump-like
device to the catheter, filling it with the
therapeutic substance. The fluid then flows, by
use of pressure and gravity, through the tumor
area. This “bulk flow” or “convective-delivery”
method bypasses the blood brain barrier,
placing the therapeutic substance in direct
contact with tumor tissue.
Clinical trials are exploring the use of CED
as a way of placing immunotoxins, radioactive
monoclonal antibodies, and various
chemotherapy drugs at the tumor site.
As this technique is developing, researchers
are simultaneously exploring ways to include
“tracers” in the substances flowing into the
brain. Those tracers can be viewed on an MRI
scan performed during CED, and may allow
researchers to make real-time observations of
the movement of therapeutic substances in and
around the tumor. Research is also underway to
predict the flow pattern that will occur after
catheter placement.

CRANIECTOMY

A craniectomy is similar to a craniotomy in
all ways except one. While “otomy” means
cutting into, “ectomy” means removal. In a
craniectomy the bone removed for access to the
brain is not replaced before closing the incision.
The neurosurgeon may perform a craniectomy if
s/he expects swelling to occur following surgery,
or if the skull bone is not reusable. When the
bone is reusable it can be replaced at a later date
when it will not cause additional pressure. The
skull piece is stored by the medical facility until
a time when it might be reused. If a craniectomy
is done, you will receive instructions from your
health care team for protecting the soft spot
created by the missing bone.

Tests

Once surgery is agreed upon, you will be
given instructions for “pre-operative” lab work.
Depending on the procedure to be done and
your age, the doctor will order blood tests and
a chest x-ray to verify your overall health. These
will be done a few days before the procedure.
Additional images of your brain may be taken
to help your doctor locate the tumor’s precise
location. These scans can also be used to
help the team plan your surgical procedure.
Highly sensitive scans are used for this purpose
and may include:
• Computerized Tomography (CT )
• Magnetic Resonance Imaging (MRI)
• Magnetic Resonance Spectroscopy (MRS)
• Positron Emission Tomography (PET)
Your doctor might request functional imaging
scans taken while you speak, read, write, or
move your arms or legs. These are called
functional MRIs, echo-planar MRIs, or ultra-
SURGERY
fast MRIs. These scans help define vital areas
of the brain which control language and
movement centers.
Vital areas can also be defined by a procedure
called brain mapping. At the beginning of the
surgery, tiny electrodes are placed on the outer
layer of the brain. Stimulating these electrodes
helps the neurosurgeon determine the functions
of those sensitive parts of the brain so they can
be avoided during surgery.

CRANIOTOMY

A craniotomy is the most common type of
surgery to remove a brain tumor. “Crani” means
skull and “otomy” means cutting into. The
procedure typically involves shaving a portion
of the head, making an incision in the scalp,
then using specialized high-speed medical tools
to remove a portion of the skull. This enables
the neurosurgeon to find the tumor and remove
as much as possible. After the tumor is
removed, the portion of skull that was cut out
is replaced, and the scalp is stitched closed.
Remember – all of this is done with drugs that
relax you or put you to sleep. They also numb
the scalp and other tissues. The brain itself does
not “feel” pain, so brain surgery can be done
with you awake if the surgeon believes it
necessary to minimize the risk of the procedure.

BIOPSY

A biopsy is a procedure to remove a
sample of tumor tissue. A pathologist then
microscopically examines the sample to
determine the exact type of tumor. The tissue
may also be analyzed for its chromosomal
makeup and other chemical (“molecular”)
characteristics.
A biopsy may be performed for the sole purpose
of obtaining a tissue sample. It may also be done
as part of the surgery to remove the tumor.
There are three types of biopsy:
• Needle biopsy. After a small incision is
made and a hole is drilled into the skull, a
hollow needle is passed through the hole
into the tumor. A small amount of tissue is
drawn up into the hollow part of the needle
for examination.
• Stereotactic biopsy. The same procedure
as a needle biopsy but performed with a
computer-assisted guidance system that aids
in the location and diagnosis of the tumor.
• Open biopsy. The tissue sample is taken during
an operation while the tumor is exposed.

Surgery Not Be Recommended?

Before surgery your doctor will consider
the following:
• Location of the tumor. In some cases surgery
may not be possible because the tumor is so
deep within the brain that it is not accessible
without excessive risk of brain damage.
Tumors located in the brain stem and thalamus
are two examples. Other tumors may present a
problem if located near a sensitive area in the
brain that controls language, movement,
vision, or other important functions.
• Diagnosis and size of tumor. If a tumor is
benign, does not cause intracranial pressure
(due to its small size) or cause problems with
sensitive areas, avoiding or postponing
surgery might be considered.
• Number of tumors. The presence of
multiple tumors creates additional challenges
to safe removal.
• The borders, or edges, of the tumor. If the
tumor is poorly defined around the edges,
it may be mixed with normal brain tissue
and more difficult to remove completely.
• Your general health. Are your heart, lungs,
liver and over-all general health not strong
enough to endure the strains of surgery? If
this is a metastatic brain tumor (one which
began as a cancer elsewhere in your body),
is the primary cancer controlled?
• Your neurological status. Do you have
symptoms of increased intracranial pressure?
Are there signs of nerve damage possibly
caused by the tumor? If so, further evaluation
may be needed before surgery is attempted.
• Previous surgery. If you’ve had recent
surgery, it is usually necessary to recover from
the previous procedure before going through
another one.
• Other options. Is it likely that another
treatment would provide equal or better
results at comparable or lower risk?
Your doctor will take these points into
consideration in forming your treatment plan.

Brain Surgery

Whether you use the word “surgery,”
“resection,” “operation,” “brain operation”
or “brain surgery,” surgery is usually the
first step in treating most benign and many
malignant tumors. It is often the preferred
treatment when a tumor is accessible – which
means it can be removed without unnecessary
risk of neurological damage.
Surgery might be recommended to:
• remove as much tumor as possible
• provide a tumor tissue sample for an
accurate diagnosis
• remove at least part of the tumor to relieve
pressure inside the skull (intracranial
pressure), or to reduce the amount of tumor
to be treated with radiation or chemotherapy
• enable direct access for chemotherapy,
radiation implants, or genetic treatment
of malignant tumors
• relieve seizures (due to a brain tumor) that
are difficult to control
“Radiosurgery” is a type of intense radiation
delivered to a tumor. It may be used instead of, or
in addition to, conventional surgery.Radiosurgery
is not surgery in the conventional sense, as no
opening is made in the skull. In certain cases,
it may offer similar benefit and lower risk or
discomfort than conventional surgery.