Treatment of SellarParasellar Tumors of the Anterior Skullbase at

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Treatment of SellarParasellar Tumors of the Anterior Skullbase at Powered By Docstoc
					Treatment of Sellar/Parasellar Tumors of the
Anterior Skullbase
at USC
  The neurosurgical treatment of lesions
that affect the sellar/parasellar region
and the anterior skull base remains
challenging. The modern treatment
of these lesions includes open surgical
strategies augmented by state of the art
modern adjuvants, such as stereotactic
radiosurgery. Tumors that affect the
sellar/parasellar regions include pituitary
tumors, craniopharyngiomas, Rathke’s
cleft cysts, meningiomas, and other less
common neoplasms and inflammatory
processes. Some of the most important
and critical neurovascular structures in
the intracranial space can be found in the
midline anterior skull base. These include
the optic apparatus, internal carotid
arteries and it associated branches, cranial
nerves in the cavernous sinus, pituitary
gland, pituitary stalk, and hypothalamus.
The optimal management of these tumors
requires that these critical neurovascular
structures are preserved while achieving
maximal control of the tumors. Failure
to preserve any of these structures can
lead to debilitating deficits that are long-   Keck School of Medicine as well as the community. Patients undergo an extensive
lasting.                                       neuroendocrine work-up. Appropriate diagnostic imaging studies are completed,
                                               along with a full neuroopthalmologic evaluation when indicated. Once a lesion has
  Typically, sellar/parasellar lesions         been characterized in this manner, the best operative and non-operative treatment
can present with neuroendocrine                strategy is outlined.
abnormalities due to hypothalamic/
pituitary failure or secretion of hormones       Despite advances in medical and radiosurgical strategies, surgical resection continues
by functional tumors, or with visual           to play a central role in the treatment of anterior skull base lesions. The mainstay
loss due to mass effect on critical            surgical approach continues to be the transsphenoidal approach. This represents the
neurovascular structures.          At USC,     most direct route to these lesions, obviating the need for brain retraction and has been
pituitary and sellarparasellar tumors          shown by numerous studies, including those conducted at USC, to be the safest way to
are managed with a multidisciplinary           treat a majority of these lesions. This approach can be undertaken via either a direct
approach that involves neurosurgery,           endonasal route, or in select cases, via a sublabial approach, using either microscopic or
endocrinology,         neuro-opthalmology,     endoscopic visualization. The most modern and advanced techniques and equipment
stereotactic radiosurgery, diagnostic          are used in all stages of treatment. For lesions that cannot be resected safely via
radiology, interventional neuroradiology,      the transsphenoidal approach, a transcranial approach is used, sometime alone or
radiation oncology, and pathology that         in combination. Given the need to preserve the critical neurovascular structures,
take advantage of the resources of the         complete resection may be impossible without unacceptable risk. In these cases,
                                                                                                                     continued on p. 2
Friends &
                                       I hope you enjoy the Second Edition          Neuroscience Intensive Care Unit with
                                     of our University of Southern California       state of the art monitoring and an
                                     Neurosurgery Newsletter. In this edition       intraoperative MRI scanner.


Colleagues
                                     we highlight the management of sellar             Colleagues and patients alike are
                                     and parasellar tumors (especially              encouraged to visit our website at
                                     pituitary tumors), our minimally invasive      www.uscneurosurgery.com.
                                     surgical spine disorders program, and          One new feature is the opening
                                     the multi-modality management of               page surgical video. Last month we
                                     trigeminal neuralgia. With the kinds of        featured a decompression of the
                                     technological advances available at USC        trigeminal nerve in a patient with
                                     University Hospital, the “one size fits all”   trigeminal neuralgia. This month we
                                     approach to neurosurgical disorders is         show the removal of a small acoustic
                                     no longer appropriate. We emphasize a          neuroma in a patient who had
                                     multi-modality and multi-disciplinary          retained hearing after the procedure.
                                     approach so that patients can feel that           Neurolink continues to be
                                     their treatment is custom made for             a successful communication
                                     them.                                          methodology for linking our
                                       The Norris Cancer Tower of the USC           Department with physicians who
                                     University Hospital will be opening            require urgent consultations or the
                                     within the next several months.                need to transfer critically ill patients
                                     The Neurosurgery Service and our               to our facilities.
                                     patients will benefit from a dedicated




    continued from p. 1

                          residual or recurrent tumors can now be treated with state of the art radiosurgery paradigms,
                          using instruments such as the Gamma Knife or Cyberknife. The patients are followed closely
                          for recurrent disease by both the neurosurgeons at USC, referring physicians, as well as by other
                          physicians at USC as appropriate.
                            Over the course of the past 30 years, the neurosurgeons at the University of Southern California
                          Keck School of Medicine have taken a leadership role in the treatment of complex tumors at
                          both the national and international levels. These efforts have enabled us to develop the largest
                          surgical experience in the management of these lesions in the Western United States. Indeed, our
                          surgical experience currently exceeds over 3000 cases operated via the transnasal approach. In
                          addition, a large surgical experience through the transcranial approach has also been compiled. In
                          conjunction with endocrinologists both in the community and at USC, an equally large number of
                          patients have been successfully managed by nonoperative strategies. The USC Center is headed up
    Charles Liu           by Dr. Martin Harvey Weiss and Dr. Charles Y. Liu.




    Martin Weiss




2
USC Minimally Invasive Spine Surgery Program
   Neck, low back, and sciatic pain are among the most common complaints encountered by physicians in the office today.
Whether due to environmental factors in the workplace or an increasingly more active elderly population, degenerative spine
disease is a chronic and progressive problem affecting a significant percentage of the American population. Besides pain, patients
with degenerative spine disease often experience numbness, weakness, and in some cases, bladder or sexual dysfunction. When
severe, disability can lead to decreased recreational activities, loss of employment and even depression.
   Increasing recognition of painful spinal arthritis is evident in the growing number of patients undergoing spinal operations
annually. Traditionally, surgery for neural decompression or spinal fusion is performed via generous skin incisions and at
times with extensive dissection of paraspinal muscles to expose the necessary spinal anatomy. The potential drawback of this
approach is that tissue injury from cutting and retracting muscle can result in increased postoperative pain, which can lead to
a prolonged hospital stay, increeased narcotic use, and lengthened recovery time.
   Recently, enthusiasm has been directed towards developing novel minimally invasive techniques for achieving the same clinical
objectives as conventional spinal surgery, albeit with smaller incisions and less tissue injury. Minimally invasive surgery (MIS)
is a principle that has revolutionized the management of many pathologic conditions across various medical disciplines. For
example, laparoscopic cholecystectomy has largely supplanted traditional open cholecystectomy due to significantly decreased
surgical morbidity, rapid postoperative recovery, and tiny cosmetic incisions. This trend towards minimalism in spine surgery
has led to the development of a broad spectrum of advanced MIS approaches and technology designed to minimize tissue
trauma without compromising effectiveness. With minimally invasive spine surgery, patients can expect less postoperative
pain, shorter hospital stays, decreased narcotic use, and a speedier recovery and return to work.
   A particularly effective MIS approach to the posterior lumbar spine is a muscle-splitting technique, known as the Wiltse
approach. Conventional posterior lumbar fusion surgery (e.g. for spondylisthesis) is performed via a midline incision with use of
electrocautery to detach the paraspinal musculature off the spinous processes and lamina. The Wiltse approach, rather than
cutting muscle attachments, employs a muscle-splitting technique, in which a natural cleavage plane between the multifidus
and longissimus muscles is developed using blunt dissection (Figure 1). In doing so, excellent exposure of the requisite anatomy
for lumbar spinal instrumentation and fusion bed preparation can be performed without disrupting muscle attachments and
with minimized retraction injury and blood loss.
   Since Wiltse first described this technique, a number of modified muscle-splitting techniques based on blunt dissection of
fascial planes have been reported. Taken one step further, the development of tubular dilators and retractors has allowed for
posterior spinal access by spreading muscle fibers, rather than dissecting muscle off the spinal column. By sequential dilation
from smaller to larger tubes placed between muscle fibers, direct portal visualization of spinal anatomy creates a working
channel compatible for performing standard open surgical procedures (Figure 2A,B). Using “through-the-tube” techniques,
although via a smaller operative corridor, spinal decompression, instrumentation, and fusion operations can be achieved
without creating large incisions or extensive soft tissue injury. Tubular dilator technology is available for both posterior lumbar
and cervical applications.




Figure 1
Illustration demonstrating blunt finger
dissection of natural muscle planes towards
the posterior lumbar spine. (Image courtesy of
Depuy Spine, Inc.)                                                                                                  continued on p.4
                                                                                                                                       3
                           Endoscopy, laparoscopy, and thoracoscopy have become important technologic
                        adjuncts in performing MIS. Endoscopic techniques are used to facilitate better
                        visualization down ever smaller working channels. Endoscopes placed through tubular
                        retractors provide illumination and magnification for performing microendoscopic
                        lumbar discectomy and cervical laminoforaminotomy. Conventional anterior
                        approaches to the lumbar spine require an extensive transabdominal or retroperitoneal
                        exposure, however with laparoscopy the same surgical objectives can be achieved via
                        three or four tiny portal incisions. Surgical treatment of ventral thoracic pathology,
                        such as a thoracic disc herniation, traditionally is performed via an open thoracotomy
                        with rib resection, or a posterior costotransversectomy or lateral extracavitary
                        approach. These procedures are associated with significant surgical morbidity and
                        result in considerable postoperative pain. Using video assisted thoracoscopic surgery
                        (VATS), the full extent of the thoracic cavity, from T1 to L2, can be visualized through
                        endoscopic ports, without taking down the diaphragm or mobilizing the scapula.
                           Percutaneous techniques have lent a new dimension to the treatment of spinal
                        disorders. Placement of spinal instrumentation by an open surgical approach
                        requires a wide exposure to identify the appropriate anatomic landmarks for screw
                        insertion. Alternatively, percutaneous pedicle screw fixation can be performed by
                        using fluoroscopy to direct placement of a thin K-wire through a tiny skin incision,
                        down the appropriate bony trajectory for the pedicle screw. Then employing a series
                        of cannulated drills and taps, the screw path is prepared for final placement of a
                        cannulated pedicle screw. Once the pedicle screws have been inserted, an innovative
                        device is used to pass a connecting rod subfascially, guiding it through the screw heads,
    Tom Chen            and locking it into place (Figure 3).
                           Management of osteoporotic compression fractures has also been revolutionized by
                        percutaneous methodologies. Osteoporotic vertebral compression fractures can lead to
                        progressive chronic pain and severe deformity. Open reconstructive surgery is generally
                        limited in this patient population due to the patient’s inherent poor bone quality, and
                        medical comorbidities. Percutaneous vertebral augmentation (vertebroplasty) is a
                        minimally invasive procedure that can be performed in the fluoroscopy suite or the
                        operating room. With this interventional procedure, a needle is passed percutaneously
                        and then through the pedicle into the affected vertebral body under x-ray guidance.
                        Once proper placement of the needle is confirmed, polymethylmethacrylate (PMMA)
                        is injected under pressure to cement the fractured vertebral body, thereby restoring
                        stability (Figure 4). Kyphoplasty is a recently developed update to this procedure in
                        which an inflatable balloon is passed percutaneously into the vertebral body, however,
                        before injecting PMMA, the balloon is gently expanded to restore vertebral height.
                        Excellent clinical results have been observed with vertebroplasty and kyphoplasty,
                        which both can be performed as same-day procedures.
                           New minimally invasive techniques are rapidly becoming available to provide
                        potentially beneficial alternatives to conventional open surgical operations. Many
                        of these procedures are being used to treat not only degenerative disease, but a
                        wide variety of pathologic conditions affecting the spine. At the USC Department of
                        Neurosurgery, a combined team of spine care specialists, including neurosurgeons
                        (Dr. Chen, Dr. Samudrala) and neurointerventionalists (Dr. Teitelbaum, Dr. Larsen) are
                        trained in performing these minimally invasive procedures. For questions, information
                        or patient referrals, please contact our clinical office at: (323) 442-5720
    Srinath Samudrala
                        .REFERENCES:
                         Wang MY, Kim KA, Hoh DJ: Minimally
                         invasive spine surgery. Contemporary
                         Neurosurgery 27(22):1-6, 2005.
                         Foley KT, Holly LT, Schwender JD: Minimally
                         invasive lumbar fusion. Spine 28(1): S26-S35,
                         2003.
                         Fessler RG, O’Toole JE, Eichholz KM, Perez-
                         Cruet MJ: The development of minimally
                         invasive spine surgery. Neurosurg Clin N Am
                         17(4):401-9, 2006
4
  What is Trigeminal Neuralgia?
  Trigeminal Neuralgia (TN), or tic douloureux, is a neurological condition
characterized by paroxysmal episodes of lancinating facial pain lasting
a few seconds. This pain is usually triggered by sensory stimuli such as
chewing, shaving, smiling, touching the side of your face, or brushing your
teeth.
  The trigeminal, or fifth cranial nerve, is the largest cranial nerve and it
divides into 3 branches once it reaches the face. They are called V1 (forehead
area), V2 (upper lip and cheek), and V3 (jaw region). The pain is usually
confined to one or more of these branches on only one side of the face.

What causes TN?
  Ninety percent of the cases of TN are       effective by gradually increasing the dose      With the glycerol injection a rhizotomy
caused by a normal artery near the brain      to where it achieves a level in the blood     or nerve injury is performed by injecting
stem which is in an abnormal position.        which provides the maximal relief of the      glycerol in this same area instead of using
This artery has a loop in it which is         symptoms. The maximum daily dose for          heat. About 85-90% of patients have a good
pressed up against the trigeminal nerve.      tegretol is 1600 mg and 1200mg-2400 mg for    result - that is, significant relief from TN
With each beat of the heart, blood is         Trileptal. Side effects include drowsiness,   pain. With this procedure there is a lower
forced through this artery which causes       staggering, dizziness, depressed white        incidence of “anesthesia dolorosa”.
the artery to bump up against the nerve.      blood cell count, and liver toxicity. Other     The benefits of these invasive non
With time, this repeat pressure rubs the      pharmacologic therapies, which may            surgical techniques is that the patient
insulation off the nerve. This causes the     help with alleviating the painful episodes    does not have to accept the risks of “major”
nerve to fire these abnormal painful          include baclofen, pimozide, phenytoin,        brain surgery and the general anesthesia
electrical-like shocks.                       clonazepam, and amitriptyline. These          associated with it. Another benefit is that
  Rarely TN can be caused by tumors, less     medications can be used in conjunction        recurrences of pain may be treated by
than 0.8% incidence, or multiple sclerosis,   with Tegretol or Trileptal but must be        repeat procedure, although the results of
3% incidence. Most of the other causes of     closely regulated by your physician. The      repeat procedures may be less successful.
TN are unknown.                               benefits of this medical treatment option
                                              include avoiding the risks involved with
                                              the invasive non surgical and surgical        Surgical
What type of work-up should be
                                              treatments.                                      The surgical procedure performed
performed in the evaluation of TN?
                                                                                            to treat TN is called a microvascular
   First of all, a good history and                                                         decompression (MVD). The MVD is
neurological examination should be            Invasive Non-Surgical
                                                                                            recommended for patients who have
performed by a neurologist. The exam             1.Peripheral Nerve Block This procedure    failed medical treatment and are in good
is usually normal except for the ability      provides temporary relief of pain by          health.
to reproduce the pain by touching the         injecting either phenol, or alcohol around
                                              the trigeminal branch involved.                  With this procedure, the patient is
trigger point. Imaging studies, such as
                                                                                            taken to the operating room and a small
an MRI scan with contrast, should be             2. Percutaneous Stereotactic Rhizotomy     amount of hair is shaved behind the
performed prior to any treatment in           (PSR) The goal of PSR is to injure the        ear on the affected side. Under general
order to rule out a tumor as the cause of     trigeminal nerve via different techniques     anesthesia, the skin is opened and a small
the pain.                                     which may include radio- frequency            piece of bone is removed. Working under
                                              thermocoagulation or glycerol injection.      the microscope, the neurosurgeon is able
What treatment options are                       In radio frequency heating, an electrode   to identify the blood vessel that is pressing
available and what are their risks            is inserted through a spinal needle under     against the nerve. The surgeon will then
and benefits?                                 radiographic guidance and certain             move it out of the way by tacking it up
   There are three categories of treatment    pain fibers of the trigeminal nerve are       away from the nerve with Teflon felt and
options available. They include medical,      destroyed by heat. With this technique        fibrin glue. The bone is then replaced and
invasive non-surgical, and surgical.          there is good pain relief in 80-90% of        the skin is closed.
                                              cases. The major complication is called          The benefit of this procedure involves
Medical
                                              “anesthesia dolorosa” which is a painful      the fact that the problem itself is treated
   The initial treatment of choice for TN     condition that is difficult to treat. When
is the medication called Carbamazepine                                                      if in fact the blood vessel is the offending
                                              this occurs the patient develops a severe     agent. There is an 85-90% initial success
(Tegretol) or Trileptal. These drugs          constant burning, aching pain which is
provide complete or acceptable relief of                                                    rate in lonstanding reduction of pain
                                              more disagreeable than the original pain.     without the need for medications and
pain in 69% of patients with TN. Neither of   This occurs approximately 2 -4 % of the
these drugs are “pain pills”. They are most                                                 70% at 10 years post operatively. This is
                                              time.
                                                                                                                                            5
 compared to the 20% success rate at 12 years post-operatively with the PSR. The
 incidence of facial numbness is also much less then with PSR, and “anesthesia             Department of
 dolorosa” does not occur.                                                                Neurological Surgery
    The mortality for this procedure is less than 1%. The most common complications         Clinical Office:
 include mild facial numbness (25% - usually temporary), hearing loss on the affected     Healthcare Consultation Center
 side (3%), double vision (usually temporary), spinal fluid leak (5%), and meningitis     1520 San Pablo St., Suite 3800
 (less than 5%)                                                                           Los Angeles, CA 90089
                                                                                          Phone (323) 442-5720
 Gamma Knife Radiosurgery (Radiation)                                                     Fax (323) 442-7543
     This procedure involves targeting focused radiation to the trigeminal nerve
 thereby injuring it     enough to keep it from firing the painful electric shocks.
                                                                                          Appointments
                                                                                          to schedule an appointment with:
 It is a good option for someone who has multiple medical problems and cannot
                                                                                          Srinath Samudrala, M.D.,
 safely undergo the general anesthesia required for the surgery. Another patient
                                                                                          please contact Annalisa at 323-442-
 population that would benefit from Gamma Knife Radiosurgery would be someone
                                                                                          5757
 who has undergone the brain surgery and no blood vessel was found pressing on
 the nerve.                                                                                 Steven Giannotta, M.D., Michael
                                                                                          Apuzzo, M.D., Martin Weiss, M.D., or
    There is a 70% success rate in amelioration of pain with or without some
                                                                                          Charles Liu, M.D.,
 continued medication. The lag time between treatment and effect ranges from 5
                                                                                          please contact Mary Ellen at 323-442-
 weeks to 3 months.
                                                                                          6290
    For further information or to schedule an appointment please contact the
 Neurosurgery Clinical Office at (323) 442-6290                                           Thomas Chen, M.D. in the neuron-
                                                                                          oncology clinic at the Norris Cancer
                                                                                          Institute,
                                                                                          please contact Bobbie at 323-865-3369.
                                                                                          For an appointment with Dr. Chen at

AneurysmTeam                                                                              the Healthcare Consultation Center
                                                                                          (non-brain tumor),
                                                                                          contact Sandra at 323-442-7542

                                                                                          J. Peter Gruen, M.D., Mark Liker, M.D.,
                                                                                          or Sherwin Hua, M.D.,
                                                                                          please contact Sandra at 323-442-7542

                                                                                          George Teitelbaum, M.D., or Donald
                                                                                          Larsen, M.D.,
                                                                                          please contact Miko at 323-442-7512
Steven Giannotta, M.D.   Don Larsen, M.D.   George Teitelbaum, M.D.   Charles Liu, M.D.
                                                                                          For issues surrounding the
                                                                                          scheduling of a surgical procedure,
                                                                                          please call Ana (323-442-5738), or Kathy
                                                                                          (323-442-6802)

				
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