The pituitary gland is a part of the brain as well as part of the
ENDOCRINE (hormone) system. The pituitary gland is rather small,
measuring approximately 1.3 centimeters (cm.) long X .8 cm. high X 1 cm.
wide (1 in.=2.54 cm.; 1 cm.=4/10 in.) It occupies a critical
anatomical position relative to the brain, brain centers, vital
CRANIAL NERVES, as well as major blood vessels (see Figure 1). The
pituitary gland is unique for several reasons. It lies within its own
protective bone casing called the SELLA TURCICA. (Early anatomists
believed that this bone cavity had an appearance similar to a
TURKISH "turcica" SADDLE sella). The sella
turcica (Figures 2 and 3) lies in the forward portion of the base
of the skull just behind and slightly below the eye sockets (orbits).
Directly in front of the sella (turcica) is the SPHENOID SINUS.
This is part of the elaborate air sinus system of the skull. The
front wall of the sella (turcica) is the back wall of the sphenoid
sinus. This anatomical fact is of critical importance for surgery
since a ready channel through the skull (the sphenoid air sinus)
can allow for a direct surgical approach to the pituitary gland
without disturbing the brain.
The pituitary gland is often referred to as the "master gland" of the
entire endocrine system. By this, it is meant that the pituitary
gland "controls" or influences the function of all the other hormone
producing glands of the body. Examples of these other glands and
their hormones are the following:
The pituitary gland also produces hormones which have a direct effect
on particular body functions. Examples of these are the following:
- Thyroid gland: This gland lies in the neck in
front of the trachea (windpipe). It makes and secretes a hormone
called THYROXINE. This hormone has a profound effect upon our
metabolism. The pituitary gland influences the thyroid gland (and
therefore the amount of THYROXINE) by manufacturing and releasing
another hormone called THYROID STIMULATING HORMONE (TSH). (In this
way the pituitary gland influences the rate of metabolism of the
- Sex glands: The ovaries as well as the testicles
manufacture and release several hormones. These are under the
influence of the hormones produced by the pituitary gland.
- Adrenal gland: This important gland lies on top
of our kidneys. It produces and releases several hormones. Among
these hormones are the "steroids." Steroids are chemical substances
which are a critical element in our ability to respond to physical
stress. Steroids are absolutely essential to our survival. The
pituitary gland manufactures and releases a substance called
Adrenocorticotropic Hormone (ACTH) which stimulates the adrenal
gland to produce steroids.
One should acknowledge that the pituitary gland serves a wide range
of functions and is particularly impressive when one considers its
small size. The gland is generally divided into three distinct
parts (Figure 4).
- Growth: GROWTH HORMONE is produced by the
pituitary gland. The relative lack of it or its absence results in
stunted growth of bones (dwarfism). The overproduction results in
one of two serious conditions. GIGANTISM (giant stature) is the
result of overproduction of growth hormone before puberty.
ACROMEGALY is the development of very prominent and characteristic
overgrowth of the skull, face, hands and feet as a result of far
too much growth hormone. However, in this case the overproduction
occurs after puberty (when growth of the long bones has ceased).
- Breast Milk: PROLACTIN (PRL) is the hormone
produced by the pituitary gland which, when released, influences
the breast to produce breast milk. Obviously there are critical
times when this is quite appropriate and necessary. During pregnancy
and after childbirth there is a profound increase in the level of
PROLACTIN in the blood stream. Alternatively the production of more
than minimum prolactin in males or in higher levels in females (who
are not pregnant or postpartum) is an abnormal situation. There
are a number of potential causes for this. However, among the
consequences there may be an increase in breast size (male or female)
possibly accompanied by breast milk secretion (discharge) through
the breast nipple. Additionally there are some possible effects of
prolactin on the sex glands and the hormones they produce.
Prolactin may reduce the testicular production of hormone. This
could result in decreased sperm production and even impotence in
males as well as decrease in body hair (particularly on the face
and chest). In females there is a significant influence upon
ovulation and a diminishment or absence of menstruation may occur.
- ANTI-DIURETIC HORMONE (ADH): Antidiuretic
Hormone is produced by cells located in the back (posterior) lobe
of the pituitary gland (Figure 4). This hormone exerts its effect
upon the kidney. It is responsible, to a large degree, for the amount
of urine that we produce. Each of our kidneys functions as a
purification filter for our blood. The blood serves, among
several purposes, to transport waste products (resulting from
our metabolic functions) away from various tissues and areas such
as muscles, liver, stomach and intestines, etc. These waste
products are then filtered from the blood by the kidneys. Vast
quantities of blood flow through the kidneys. The fluid that is
filtered must, to a degree, be excreted as urine. However most
of the filtered fluid must be reabsorbed in order to maintain as
adequate fluid volume for the blood. Antidiuretic hormone acts
upon the kidney to force it to REABSORB more fluid. The absence
of ADH results in the production of very large quantities of urine.
Abnormal medical conditions in which there is a relative lack or
complete absence of ADH do occur. This medical condition is
called DIABETES INSIPIDUS. This is NOT diabetes mellitus ("sugar
diabetes") which is related to deficiency of insulin production
by the pancreas. Diabetes insipidus can be a life-threatening
condition, although it is usually less serious. It is treated
by using a medicine whose function substitutes for the lack of
the naturally available substance.
The ANTERIOR (FRONT) LOBE is the largest portion. It consists of a
number of different cell types. Each cell type serves a specific
purpose. Thus, some of the hormones previously described, such as
PROLACTIN, THYROID-STIMULATING HORMONE, GONADOTROPIC HORMONE,
ADRENOCORTICOTROPIC HORMONE AND GROWTH HORMONE (and there are
others), are produced by individual cell types. In other words,
one cell (or similar cells) produces only one kind of hormone.
The cell type that is most numerous of any of the different kinds
of cells is the "ordinary pituitary gland cell" (known as the "true
chromophobe"cell). It does not appear to serve any hormone-related
function at all.
The POSTERIOR (BACK) LOBE is the smaller of the two lobes of the
pituitary gland. Its primary function is to produce Antidiuretic
Hormone (ADH). Between the two lobes of the pituitary gland is a
narrow, dividing band called the PARS INTERMEDIA.
While the PITUITARY GLAND is generally regarded as the Master Gland,
in actual fact it is strongly under the influence (and in some
instances the control) of the HYPOTHALAMUS. The hypothalamus is
directly in the center of the brain. It is the general region where
many vital life functions are monitored. It responds to changes of
the body's internal environment and function by directing the
pituitary gland to release selected types and quantities of
hormones in order to influence other organs to perform specific
functions or alternatively to influence those organs or glands to,
themselves, produce and release other hormones. All of this is
done in an effort to MAINTAIN INTERNAL STABILITY OF THE BODY AND
ITS MANY FUNCTIONS.
As an important example (but by no means the most important), let
us examine the body's ability to maintain a relatively constant,
narrowly ranging, concentration of a substance called Sodium.
(Most of us are more familiar with its common name, Salt.
Actually table salt is a purified version of a compound made up
of two substances, sodium and chloride). Sodium is vital to
many chemical functions of the body. However, too much or too
little could have disastrous results. One of the most fundamental
requirements for life is to maintain a "normal" concentration
of sodium in our cells, tissues and serum (the fluid component
of blood). In order to maintain the correct relative
concentration of sodium in our serum, there is a highly integrated
system that monitors the concentration (monitors exist in the
hypothalamus) of sodium in our serum and reacts to the actual
serum levels. It directs the POSTERIOR LOBE of the pituitary
gland to release more (or less) Antidiuretic Hormone (ADH) in
order to influence the kidneys to reabsorb more (or less)
filtered blood. This results in less (or more) urine production.
If more urine is produced then less fluid (water) is present in
the serum; therefore, the concentration of sodium will rise.
In the event that sodium concentration is too high, then the
special sensing area of the hypothalamus will direct the posterior
lobe of the pituitary gland to release MORE antidiuretic hormone.
The kidney responds to the increase in ADH by reabsorbing more
filtered serum. (Obviously LESS urine will be produced). The
increase in reabsorbed water in the serum results in the
desired lowering of the relative concentration of sodium.
The hypothalamus has "centers" dedicated to the regulation of
body temperature as well as the amount of food that we eat (food
satiation). The hypothalamus exerts a strong influence upon the
pituitary gland in another way. Examples of this are in the way
the anterior lobe of the pituitary gland manufactures and releases
some of its hormones. The HYPOTHALAMUS produces releasing-factor
hormones which have the solitary function to control the pituitary
gland's production of a particular hormone. You are now familiar
with the production of PROLACTIN by a particular cell type in the
anterior lobe of the pituitary gland. (The release of
abnormally high levels of this hormone usually results in an
increase in breast size, breast milk production and lack of
ovulation in females. A decrease in sex hormones in males may
occur depending on several factors). Prolactin production and
release is under the influence of the HYPOTHALAMUS. Obviously
this is a highly complicated biochemical, anatomical and
physiological system. It is remarkable how well the whole thing
functions over our life span and how infrequently the systems
fail despite the many extremes visited upon our bodies from many
different sources and directions.
Tumors of the brain are, in relative terms, uncommon in the general
population. Nevertheless, they certainly do occur. Among all brain
tumors, fifteen (15%) percent are classified as PITUITARY GLAND TUMORS.
The vast majority (99%) of all pituitary gland tumors are BENIGN.
That is to say, they are NOT cancerous (malignant). However, they
are very clearly tumors (new growths) which continue to grow in size.
As a general principle, the tumors can, and frequently do, grow to
sufficiently large size to press upon and possibly injure vital
adjacent structures such as the optic nerves, pituitary gland,
cranial nerves which control the muscles that move the globe of the
eye and the blood vessels supplying blood to the brain. (See Figures 5
The most frequently occurring type of pituitary gland tumor is one
that comprises the "ordinary pituitary gland cell" (chromophobe cell).
Most pituitary tumors are relatively slow growing. The brain and
its nerves can accommodate to the progressive compressing force of
a slowly expanding tumor. However, there comes a point where the
brain, nerves and the blood supply to the nerves can no longer
tolerate the progressive expansion and function is progressively lost.
This is true for the pituitary gland itself as well as the adjacent
structures. The loss of function, both hormonal and/or related to
adjacent structures, can be quite insidious. Because the tumor
grows slowly, the patient may not recognize any change. In some
cases the degree of pituitary gland function impairment and/or
visual disturbance may be far advanced before the diagnosis is
Tumors of the pituitary gland may arise from any of the different
kinds of cells. In the case where the tumor consists of cells which
produce a hormone, then there will be, in addition to any effects of
pressure injury, the additional consequence of the over production of
the particular hormone that the specific cell type produces. If the
cell type involved in the tumor is the one which produces prolactin,
then the serious consequences of the over abundance of prolactin
will result. Alternatively, in the event that the cell type
producing the tumor is the one which produces ACTH or GROWTH
HORMONE then the patient will exhibit the manifestations of these
hypersecretions of hormone. It should be obvious that there are
many variations and spectrum of gradations of involvement of any of
these abnormalities which can exist.
Tumors which produce a hormone may become obvious to the patient
and the physician when the tumor is quite small. The hormonal
effects of the tumor may be sufficiently profound to bring the
matter to attention long before the tumor becomes large enough to
produce a pressure injury. Levels of hormone concentration can
be measured in the blood. This is among the important ways by
which a correct diagnosis can be achieved as well as an important
tool in measuring the success of treatment. Long-term follow-up
for these patients includes the monitoring of the appropriate blood
hormone concentration in order to determine the possible early
recurrence of the tumor or help direct any further treatment
The problem of visual impairment and its relationship to pituitary
tumors is worthy of some additional comments. As the tumor grows,
it presses against the walls of the bony confines of the sella
turcica. It frequently erodes the bone sufficiently to become
obvious on x-rays of the skull. Further growth of the tumor
results in the expansion of the tumor beyond the sella turcica.
The continued tumor growth follows the line of least resistance.
This is in an upward direction, out of the sella, and produces
pressure on the underneath surface of the brain. In addition to
pressure upon the hypothalamus, it also progressively stretches
the optic (eye) nerves over the top of the tumor. Of equal
significance is the concomitant stretching of the small blood
vessels which supply blood and nourishment to the optic nerves.
All of these structures can tolerate remarkable degrees of
stretching provided the tumor growth is slow. Ultimately the
optic nerve will no longer tolerate the actual stretching nor
the diminished blood supply and the function begins to deteriorate.
It is important to recognize that the progressive loss of vision,
in these circumstances, is a LATE EVENT IN THE NATURAL HISTORY OF
THESE TUMORS. It is a late event because the tumor usually must
grow to a substantial size before it stretches the optic nerves
and their blood supply.
There are tumors in the region of the pituitary gland which may
arise from other structures. Their clinical presentations may be
indistinguishable from those of pituitary tumors. Some of these
other tumors actually arise inside or extend into the sella
turcica. Frequently the investigations (blood tests, special
eye examinations, x-rays, etc.) will help to determine the
probable tumor type. A firm diagnosis is possible only with a
The investigation of a patient who may have a pituitary tumor
usually begins when some particular problem has been noted by
the patient. Headaches, unexplained visual impairment, double
vision and hormonal difficulties (including infertility) are
among the more common complaints that ultimately lead to the
suspicion of the presence of a pituitary tumor. On occasion
the diagnosis is made on the basis of a routine skull x-ray) or
other neuro-imaging techniques such as Computerized Axial
Tomography CAT SCAN or Magnetic Resonance Imaging
l; MRI Scan) which was made for some reason other than the
suspicion of a brain tumor (such as x-rays for investigation of
a minor head injury).
Among the early steps in the evaluation of any patient with these
problems is a detailed history and physical examination. Areas
to be explored in the history of the illness, as it affects each
particular patient, include historical hormonal aspects of life.
It should be apparent that these matters are complicated and
their clinical manifestations can be quite variable. Most major
medical centers with experience in these matters have a TEAM OF
EXPERTS who investigate and treat these conditions. The knowledge
and techniques required for all of this extends into a number of
related but different, medical and surgical disciplines.
The medical specialty of ENDOCRINOLOGY is a branch of
Internal Medicine which specifically involves itself with the
diagnosis and medical treatment of all abnormalities of the
ENDOCRINE (HORMONAL) SYSTEM. In the case of a patient with a
pituitary tumor certain initial blood tests help to determine
the status of basic hormonal and pituitary gland function as
well as levels of the various hormones which are produced by
the pituitary gland. Further tests are usually done to
"challenge" the function of the body's ability to tolerate
stress. These are biochemical evaluations involving taking
some tablets by mouth and having blood samples drawn at certain
times over the next day or two. More elaborate urine analysis
for hormone by-products is also done on occasion. The
interpretation of these results can be readily apparent to many
physicians; however, more frequently an accurate interpretation
requires the expertise of the endocrinologist. A more ideal
situation results when the endocrinologist is involved in the
early stages of the evaluation. In the event of the possible
use of medications to attempt to control the problem, in the
preparation of the patient's endocrine system for surgery, or
in the early and late post-operative medical management, the
endocrinologist's expertise is frequently of vital importance.
The eye manifestations of tumors of the pituitary gland constitute
an important aspect of these diseases. Frequently it is only
the symptom of a "visual problem" that brings the matter of a
pituitary tumor to the patient's and the physician's attention.
The medical specialty of NEURO-OPHTHALMOLOGY involves
itself with the diagnosis (and frequently treatment) of those
many neurological conditions which manifest themselves through
impairment of eye function. Special tests for vision and eye
movement function are carried out by these specialists. In
addition, certain electronic (neurophysiologic) tests may also
be carried out or supervised and interpreted by the
Neuro-ophthalmologist. Visual Evoked Responses (VER's) are
among the techniques available to examine for subtle impairments
of visual function by "measuring" (with the aid of advanced
computer technology) changes in the miniature electrical brain
waves which result when a light is flashed in front of the eye.
The examination is painless and virtually without risk. This
test may become very important in the surgical treatment of
certain patients with pituitary and pituitary region tumors
since it can help to gauge the tolerance of the visual system
to surgical removal of the tumor while surgery is in progress.
The NEURORADIOLOGIST is the physician who will supervise,
conduct and interpret all of the "IMAGING" tests that are done.
These tests will help the physician team to "visualize" the
tumor as well as its affect upon anatomical structures in the
area, including the hypothalamus, pituitary gland, optic nerves,
bone of the sella turcica and major cerebral blood vessels. The
anatomical area of the skull that is involved in these cases is
regarded as part of the SKULL BASE, and as such represents
a unique set of technical problems and considerations as well
as a very special and focused interest for a special group of
surgeons. The most basic x-ray test is the skull x-ray which
gives some details concerning the bone anatomy of the sella
turcica and important adjacent bone structures. The extent of
erosion caused by an expanding tumor in the sella can be
evaluated better using other techniques. CAT scans as well as
MRI scans give us new, advanced techniques to "see" inside the
head. Unfortunately, although indispensable to modern diagnosis
and treatment of these diseases, they are not without their
technical limitations. Special advanced expertise is required
in order for the Neuroradiologist to direct the technical aspects
of the "picture taking" as well as interpreting the results.
Cerebral angiography is a special test which evaluates the blood
supply to the brain and pituitary tumor as well as examining the
effect of the tumor on the blood supply to the brain. Anatomical
variations of the cerebral (brain) blood vessels are common;
however, they only infrequently are of major consequence for the
treatment of the tumor. Unfortunately, we are occasionally unable
to predict these very serious problems without some form of
angiogram. As an example, the major blood supply to the brain
is through two large blood vessels (the Internal Carotid Arteries)
which lie on either side immediately adjacent to and in front of
the pituitary gland, separated from it by a thin layer of bone
(see Figure 6). In four (4%) percent of humans, the two carotid
arteries lie sufficiently close together (less than one inch)
so as to limit the neurosurgeon from safe considerations of
pituitary surgery through a transphenoidal approach (figures 7).
Injuries to the carotid arteries (resulting in catastrophic
exsanguinating hemorrhage or impairment of blood supply to brain
and a possible stroke) are, to the largest extent, avoidable by
determining (prior to surgery) if there is a safe distance
between these vital blood vessels. Additionally, certain very
serious blood vessel problems (known as aneurysms) can masquerade
as pituitary tumors. Another potential surgical disaster is
avoidable when the angiogram and/or MRI forewarns of the presence
of the aneurysm. These are but two (albeit more important) of
the indications of cerebral angiography.
There are choices in techniques of angiography. Some advanced
computerized techniques permit the neuroradiologist to obtain the
same information without some of the discomfort and risks of more
traditional, but modern, techniques. The newer, high-resolution
MRI and/or CT scans frequently give us most of the information
that we need in checking vital blood vessel anatomy that is
sufficient for us to avoid angiography. Your Neuroscience
physician team will explain their recommendations for the most
appropriate test for you. Oftentimes only one of these
examinations is required to fulfill the anatomical information
needs for your surgeon.
In summary, not all of these techniques are necessary for each
patient. In all cases, either a CAT scan or an MRI scan will be
required. In addition, some form of visualization of the vascular
(blood supply) system (i.e. angiogram) may also be necessary. We
are frequently referred patients who have had some form of scan
performed elsewhere under less optimum conditions. In these
situations it is often necessary to repeat at least part, if not
the entire, scan. Additionally, even if the scan has been
conducted in an expert fashion, we may need further anatomical
information which can only be obtained using scanning techniques
which are not routine. In some patient situations all of these
techniques will be called upon to gain the information that the
team needs in order to satisfactorily evaluate the situation and
make the appropriate recommendations. The Neuroradiologist will
discuss all of the Neuro-imaging aspects with the patient and
is always pleased to take time to answer any questions concerning
the performance and interpretation of the tests.
Surgical treatment of pituitary and pituitary region tumors enjoys a
prominent and long history in Neurological Surgery. Modern
microsurgical techniques have progressively evolved to the present
day circumstances in which the patient and their families can be
comforted by the fact that surgery has proven to be reliable, quite
safe (considering we are dealing with a brain tumor) and effective
on a long-term basis. This does not mean that surgery is indicated
or necessary in every case nor that it is entirely free of risk
for potentially serious complications. What it does very clearly
mean, is that given (a) modern Neuro-imaging techniques that allow
for pinpoint, accurate neuroanatomical "maps," (b) modern
Neuro-anesthetic techniques, (c) modern, effective endocrinological
management (d) advanced micro-neurosurgical instrumentation and
techniques (including visual evoked responses conducted during
surgery when this is appropriate), and (e) an experienced neurological
surgeon (and a team of dedicated skull base tumour surgeons), the
risks to the patient of surgery are decidedly less than the
expected natural history of the disease (in the case of larger
tumors) and more reliable than the long-term medical treatment
of most of these tumors.
In the cases of very small tumors of the pituitary gland, medical
treatment may be the most appropriate therapy. This is particularly
true for small, prolactin-secreting tumors. These patients may
ultimately be referred to neurosurgeons, specifically for the
purpose of tumor removal, after medical treatment has either failed
or been abandoned because of intolerable side effects. In other
selected cases, medical treatment is used initially in an attempt
to reduce the large size of a tumor to a more reasonable one,
thereby making surgery easier on everyone. Medical treatment
is most effective (at the present time) for tumors which produce
prolactin. It is very much less effective for tumors which produce
growth hormone although medical treatment is available and can
be effective in some patients. It is probably ineffective for
any other pituitary tumors (whether or not they produce hormones).
For prolactin-secreting tumors which have not been or cannot be
entirely removed surgically (or which recur), medical treatment
may become an important part of their long-term management.
Radiation (super voltage/cobalt) therapy can be very effective
in the treatment of pituitary tumors. One ordinarily believes
that radiation treatment is used for cancerous tumors, and we
have already noted that most pituitary tumors are entirely BENIGN.
Pituitary tumors can and often do respond very favorably to
radiation therapy. However, this technique is used only when
absolutely necessary. It is rarely ever used as a primary form
of therapy. It carries with it some risk to serious side effects,
particularly with larger tumors (in which cases it is also less
effective), and is ineffective for certain kinds of tumors.
The only way to be absolutely certain of the precise kind of
tumor that is present, is by examining the tissue by various
pathology techniques (microscopic analysis, special
tissue-staining techniques, immunochemical analysis, etc.).
This can only be done with a surgical biopsy. The process of
"surgical biopsy" may also allow for the selective removal of the
entire tumor thus obviating the need, in most cases, for any
further treatment. In those patients where, for whatever reasons,
a complete tumor removal cannot be accomplished then surgery not
only permits an accurate diagnosis, but usually also allows for
the removal of the largest bulk of the tumor. This accomplishes
two important treatment objectives. First, in the case of
large tumors which are involving the optic nerves and possibly
their blood supply, the pressure upon the optic nerves can be
reduced, if not totally relieved. This is very important since
radiation therapy results in, among other effects, a swelling
of the tissues being radiated. As a general rule radiation
therapy will not be offered unless the optic nerves have been
relieved of the pressure in order to reduce the risk of producing
blindness as a result of the radiation. Secondly, radiation
treatment is appropriate for certain tumors only. An accurate
tissue diagnosis is a prerequisite, in almost all instances,
for accurate effective treatment.
The most modern form of radiation therapy incorporates
a concept called stereotactic or "focused beam"
radiation therapy. There are several commercial types
currently available. The latest technique is called "Cyberknife"
or "Accuray" while another is known as "Gamma Knife". These
exceptional methodologies have limited indications and
applications. Nevertheless, when appropriate they represent a
major advance in the treatment of some of these problems.
A full discussion of this is beyond the scope of this review.
They will be discussed if you ask or if it is a reasonable
alternative form of therapy.
For most pituitary tumor patients the treatment of choice is
surgery. Among the surgical alternatives, there is one
technique that is more desirable, for several significant
reasons, than any other type of surgery. This Microsurgical
method of tumor removal is performed through a relatively small
opening in the front wall of the sella turcica (see Figures 7
and 8). The operation is actually done with an incision in
either one nostril (or rarely just beneath the inside of the
upper lip) and uses a surgical avenue through the sphenoid sinus
to gain access to the sella. This technique allows the surgeon
to view the compressed remnant of the pituitary gland, thus
permitting a more reliable way to attempt to save the damaged
gland and its function. This technique frequently allows for
the opportunity for a selective total removal of the pituitary
tumor while preserving the remaining, compressed pituitary gland
(which usually lies to the back and side of the expanded sella
Unlike the other surgical techniques which require a craniotomy
(window-like opening in the skull) and retraction (lifting up)
of the front part of the brain to gain access to the top of
the pituitary tumor (which has the stretched optic nerves
lying over it), the Transphenoidal approach avoids all
of this. The tumor is seen directly through a tiny bone
opening (frequently smaller than the fingernail of the fifth
finger) and is removed piecemeal with special microsurgical
instruments and occasionally with an advanced micro-neurosurgical
laser. The tumor is removed from below the eye nerves without
touching them. The surgery usually takes less time, is less
stressful upon the patient and is usually associated with
considerably less blood loss than any other surgical technique
available for these problems.
A modification of the Transphenoidal technique involves the use
of Endoscopic surgical instruments. This can be done either
in conjunction with the Microsurgical procedure or as
part of a Minimally Invasive Microendoscopic technique.
An Endoscope is a long slender instrument which incorporates
modern optics as well as a high intensity light source to permit
operations to be done through "tiny keyhole-like" openings in
the skull. The surgeon is able to "see" anatomical structures
quite well due to the clarity of the optics, intense light, high
resolution miniaturized video cameras along with specially
designed instrumentation. One of the additional advantages for
Endoscopic Transphenoidal Surgery is the fact that
post-operative "packing" of the nasal cavity is rarely required.
This usually also shortens the patient's length of stay in the
Occasionally transphenoidal surgery cannot or should not be used.
In those patients in whom the internal carotid arteries are closer
than one (1) inch, it is best to avoid this operation because of
the serious risk of injury to these vital arteries. It is usually
advisable to use a craniotomy approach in those cases where the
tumor has extended to either or both sides above the sella. Tumor
above the sella is usually accessible using transphenoidal surgery
(actually that is one of its major advantages). However, tumor
above the sella that has gone beyond the range of the side walls
of the sella usually cannot be safely approached or removed from
below because of the risk of injury to the internal carotid arteries
inside the skull cavity. A craniotomy technique allows the
surgeon to directly view the carotid arteries inside the head and
reduces the chance of injuring them.
There are some tumor types which cannot or should not be removed
using the transphenoidal technique and are best managed using a
craniotomy. These limiting factors to transphenoidal surgery are
fortunately relatively uncommon, permitting its use in most cases.
Occasionally we encounter a tumor which has either a very firm
texture which will not respond to available resection methods
or has a very firm tough surrounding capsule which will not
collapse as tumor is removed. In this case the transphenoidal
technique may fail to adequately decompress the visual sensory
system. This unusual circumstance may then require a second
surgical procedure via craniotomy to resect that firm capsule.
In our practice, a surgical team comprising experts from different
surgical specialty areas is involved in the care of the patient.
(Each patient will be informed as to which specific doctors will
be involved in their care.) An Otorhinolaryngologist
Head and Neck surgeon (formerly ENT) - usually performs the
surgical approach through the nose to the sphenoid sinus. On
occasion, when a more extensive opening is required, a
Craniofacial Plastic Surgeon may join the surgical team.
In the event that this special expertise is needed, it will be
discussed with you. After the Neurosurgical team removes the
tumor and has completed the repair of the sella turcica, the
ENT (or Craniofacial Plastic) surgeon returns to complete the
repair of the nose and/or face.
The Neurosurgical team consists of a neurological surgeon
and an assistant, which may be a surgical Neuro-ophthalmologist
or another Neurosurgeon. The neurosurgeon opens the
sphenoid sinus and selects the area in the front of the sella
turcica that he will open. This choice is made by directly viewing
the front of the sella (through the sphenoid sinuses) using the
Neurosurgical Microscope, as well as by x-ray imaging of the
skull and this region. X-rays are taken at intervals throughout
the procedure in order to help guide certain important aspects
of the operation (See Figure 7). Another technique utilizes an
endoscopic approach through a similar route. In this case the
surgeon is using a different type of visualization system
compared to the operating microscope. The endoscope may be
used instead of the microscope or as an adjunct depending on
the anatomical requirements for the particular tumor and
Once the sella is opened, the underlying covering (the dura mater
which is a tough, leather-like covering of the brain) is
opened. The pituitary tumor lies directly in view in most cases.
The tumor is removed in a piecemeal fashion with special
microsurgical instruments. Frequently, a neurosurgical laser
is used as well. Every effort is made to attempt to remove the
entire tumor or, if this is not possible, then as much tumor as
can be resected. A similar effort is made to try to save the
already seriously compressed pituitary gland. It is important
to know that, despite these efforts, even if the pituitary
gland is left anatomically intact, it may never function properly,
or at all, again Alternatively it may stop all of part of its
functioning for an indefinite (usually short) time after surgery
and subsequently resume its activity in part or completely.
One of the very important aspects of the removal of these rumors,
particularly where vision has been impaired or is at serious risk,
is to protect and try to improve upon the damaged visual system.
We have the capability to monitor visual function using advanced
neurophysiology techniques (a technique called Intraoperative
Visual Evoked Response [VER] monitoring while the operation is
being done (the patient is asleep under general anesthesia).
In the event that these tests indicate that vision is being
impaired by the removal of the tumor, then the procedure
will be modified to try to change this. Although this is
uncommon, it is a possible limiting factor since we prefer to
save vision first even at the expense of leaving some tumor
behind. We can usually use radiation therapy postoperatively
to try to deal with the rest of the tumor.
At the completion of the neurosurgical procedure, it is
necessary to seal the hole in the front of the sella (Figure 8).
This is of critical importance for several reasons. Cerebrospinal
fluid (the fluid which bathes and cushions the brain inside
the skull) could leak out through the hole in the sella. A
leak, postoperatively, of cerebrospinal fluid is a very
serious complication. If fluid can get out, then bacteria
can also enter (from outside) to the brain area and cause a
serious infection (meningitis). Every effort is made to
prevent this. A piece of muscle (which will be taken from
the thigh muscle of the patient through a short skin incision
earlier during the operation) and/or a piece of fat will be
placed in the sella turcica to fill part of the void left by
the tumor removal. This is the first of several layers that
will complete the seal. The muscle also helps to prevent
bleeding by pressing gently against the "walls" where the
tumor was. Additionally it helps to prevent the optic (eye)
nerves from herniating down into the sella turcica. Where
the optic nerves were stretched over the top of the tumor,
they have become elongated. Now that the tumor is out, there
would be nothing to prevent them from falling into the empty
pit in the sella. This could stretch them and their blood supply
resulting in the same kind of problem that the tumor caused,
except in the reverse direction. The muscle/fat helps to keep
this from happening.
After the muscle/fat is placed, then a piece or pieces of
nasal cartilage and bone are usually used to tightly seal
the small bone opening in the front of the sella turcica.
A final seal is made with the use of a rapidly setting,
special glue. This technique has helped to reduce to a
minimum the risk of cerebrospinal fluid leak in our patients.
However, it is very important postoperatively to avoid
sneezing, nose blowing or activities that require straining.
These activities result in increased intracranial pressure.
This pressure could be transmitted to the repair site and
cause a leak.
As a general rule, the risks to this operation are statistically
small; the results are quite reliable and favorable. However,
as in any operation, there are risks. The operation is
conducted under general anesthesia by an Anesthesiologist.
The anesthesiologist will talk with you about the anesthetic
and answer any questions which you might have. The risk to
life has been reduced to a small fraction largely because of
the advances in modern anesthesia.
There is a risk to recurrence of the tumor even if we believe
we have removed all of it. In all cases, long-term follow-up
is essential. Radiation therapy may be necessary postoperatively
where we know tumor remains or if tumor recurs at some later
The likelihood of producing any injury during surgery is very
small. The risk to injury to the carotid arteries and causing
hemorrhage or stroke is very unlikely. Similarly, the risk to
further injury to vision, even to loss of vision, is small.
However, vision that has already been lost may not recover or
may not completely recover.
There are vital structures adjacent to the tumor and the
operative region. There is a very small risk that they could
be injured. The nerves which control the movement of the globe
of the eye, if injured, may never recover. This could result
in double vision or trouble opening the eyelids. Injury to the
hypothalamus is very unlikely, however it could cause difficulty
with body temperature regulation, hormone control and body
fluid and electrolyte (sodium, potassium, etc.) control.
Most patients use a supplemental steroid hormone postoperatively
(taken as pills). Other hormones, depending on the needs of
the individual patient, may also be required. These may be
necessary on a permanent or long-term basis or just for a short
time. The endocrinologist will help to decide and monitor these
One cannot emphasize strongly enough the absolute necessity for
long term follow-up on a regular basis. Even though the vast
majority of these tumors are of a benign cytological (cellular)
nature, there is a significant risk to the recurrence of some of
these. The surgeon may well believe that he has removed the entire
tumor. Nevertheless, the surgeon cannot be expected to "see" at
a cellular level and some miniscule remaining tumor may not be
apparent. More often than not if the surgeon believes that a
complete resection has occurred then recurrence is very unlikely.
I am still unwilling to pronounce a surgical "cure" in these
patients. In each instance the surgeon will fully share his
impressions and recommend a follow-up schedule which will
include MRI scan at some interval.
We realize that it is impossible to answer every question that
might arise through this group of "papers". We would like to
encourage the reader to read and re-read these sections and
consult the diagrams. Members of our staff will be happy to
answer whatever questions you may have concerning these or
any other matters.
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This page last edited on 2/20