Acoustic neuroma surgery

Acoustic neuroma treatment options in general

The options open to AN patients are basically:

• surgery,
• radiation,
• watch & wait (no treatment).

Before deciding on the type of treatment you want, ensure that you know all your options.  We recommend that you start with the treatment options page. This page is for patients who are contemplating surgery. Other pages explore radiation treatments and wait & watch options.  You are strongly advised to read them all before making any decision.

Reasons to choose surgery rather than radiation

1. Desire to get the tumor "out of your head"
2. Fear of unknown long-term effects of radiation, such as induced malignancy
3. Size and/or position of the tumor makes radiation unadvisable (because swelling can occur after radiation treatment)
4. The tumor has a cystic component (see comments below)
5. Prior radiation treatment in the same area

INTRODUCTORY COMMENTS ABOUT ACOUSTIC NEUROMA SURGERY TREATMENTS

Key in the decision making process is determining the best type of surgery for an individual situation. Ultimately the question is, "What should I do?" and "How do I decide what to do?" Oftentimes, it ends up that the surgery decision is limited by circumstances. It is our hope that this page will help assist you in forming the right decision in coordination with the medical advice obtained through consultation.

Surgery is the oldest form of treatment for acoustic neuroma tumors. This page will detail a brief description of each surgical approach and link to some common websites for further information. Depending on the patient's tumor size and location, there are four goals in surgery: patient safety, total/partial tumor removal, facial nerve preservation and hearing preservation. It is important to understand the physician's priority order and match it with the individual patient's priorities.

AN surgery requires exceptional care and precision and it is recommended to choose a surgeon with experience of at least 100 surgeries using the same technique, on a regular basis, recently, and with good outcome statistics. Choosing the correct medical professional and facility is critical in obtaining the best outcome. It may require travel outside of your immediate local area. A study conducted by Wiet et al, concluded that tumor size and the surgeon's experience are the most significant factors influencing the facial nerve status and hearing outcome after acoustic neuroma removal.

When selecting a physician, request statistics relative to his/her own patient outcomes rather than general industry standards. Request the number of operations performed using the type of surgery you are considering. For example, if the surgeon indicates that he/she has performed 500 surgeries, request a breakdown by surgery type. It may be that the majority of operating experience is with translab, which may not be the right choice if you are considering middle fossa.

The 3 different surgical approaches have different goals. They are discussed in detail below, but basically Translabyrinthine surgery, which is the oldest approach, sacrifices hearing in the AN ear, while making it easier to avoid damage to the facial nerve. Advances in technology and surgical tools make both facial nerve preservation and hearing preservation a reasonable expectation in some patients undergoing the Retrosigmoid approach, (also known as Suboccipital), and the Middle Fossa approach. Mainly this includes the ability to monitor the facial and hearing nerves during the surgery and the use of sophisticated surgical tools. When damage to the facial nerve is feared, a technique called "debulking" is increasingly considered. This is a partial removal of the tumor that may be followed up with radiation treatment in case of regrowth.

Because surgery has been used for a long time, there is much peer reviewed data to support prognostic factors for the various post surgical outcomes. It is very important to use recent data in the journals and your physician's data when reviewing the probable outcomes. Remember however that each tumor is individual and some attributes cannot be determined ahead of time.

Surgery in expert hands lasts approximately 4-6 hours. Surgical teams usually include at least two surgeons: an ENT and a neurosurgeon. Typically, the ENT opens the patient and the Neurosurgeon removes the tumor.

3 basic surgical options:

• Translabyrinthine

  The oldest surgical approach is translabryinthine. This procedure provides the best line of sight of the facial nerve and consequently offers the highest success rate of facial nerve preservation for a patient. The downside is that this procedure sacrifices an individual's hearing. It should only be selected when a person has severe hearing loss or the tumor is too large for hearing preservation surgery. Translab is the preferred surgical choice by most doctors when the hearing level is no longer useable. It is also a good choice when a tumor is above 20 mm as, statistically, facial nerve damage increases with large tumors.

  The entry is behind the ear in which the mastoid bone and some bone in the inner ear is removed. An excellent video illustrating this procedure very clearly is available (in French).

• Middle fossa

  This approach will be used to attempt hearing preservation. Statistics show that the better the hearing one has ahead of the operation the better the chances of good hearing preservation. The location of the tumor on the superior nerve vs. the inferior nerve is better. The HEI website states that "In patients with small tumors who have been operated by the middle fossa approach since 1992., good hearing has been preserved in roughly two thirds of those patients. Any measurable level of hearing was preserved in 80%." It has higher hearing preservation rates for tumors under 2 cm than retrosigmoid. From the HEI website, it states that: "95% of 380 patients undergoing MF maintained excellent facial nerve function. Only five percent suffered minor weakness of facial nerve function."

  The incision is made in front of the ear by creating a bone flap. There is an unobstructed view of the entire IAC with this surgical approach. This allows complete tumor removal. The middle fossa approach is performed by lifting of the temporal lobe of the brain. This approach is not recommended for patients above 60. At House Ear Institute, in a review of 500 cases with several years of follow-up, they identified only one case of residual tumor (0.2%).

• Retrosigmoid (suboccipital)

  This approach is used to attempt hearing preservation. Success rates vary from 30-65% in CPA tumors smaller than 1.5 cm with good hearing and limited involvement of the IAC. However a tumor extending to the fundus is a contraindication to the RS approach for hearing preservation. The tumor removal is accomplished with mirrors.

  Also reported is a "10% incidence of severe postoperative headaches" with this approach (Sliverstien et al, 1991) cited in Brackmann's paper.

Other situations that involve micro-surgery

• Cystic tumors The following is an e-mail sent by Dr. Kleinberg to the JHH listserv.
  
  "Some patients have a large cyst (fluid filled area) causing major pressure on the brain stem or other structures which cause substantial symptoms.
  
  In that less common situation where significant symptoms are resulting from pressure from a large cyst, surgery would be a useful way to remove the fluid and immediately relieve that pressure.
  
  Otherwise, both microsurgery and fractionated stereotactic radiosurgery are appropriate choices, and, as we alway point out, the decision should, for each patient, be based on a good understanding of the risks and methods used in each approach in their individual situation. A recent paper about outcome with radiosurgery (a different FSR regimen) examined the issue of cystic versus non-cystic neuroma. This reference is included below for anyone who would like to read more about this issue."

  Int J Radiat Oncol Biol Phys 2000 Dec 1;48(5):1395-401 Fractionated stereotactic radiotherapy for vestibular schwannoma (VS): comparison between cystic-type and solid-type VS. Shirato H, Sakamoto T, Takeichi N, Aoyama H, Suzuki K, Kagei K, Nishioka T, Fukuda S, Sawamura Y, Miyasaka K.

• Debulking

  There are times when a tumor cannot be safely totally removed creating conditions where partial tumor removal is considered or a surgeon decides for subtotal resection to save the cranial nerves. Situations which might warrant partial tumor removal include:

  1. When the tumor is in a patient's only hearing ear
  2. When the tumor size or location present a challenge if total tumor removal were attempted.
  3. When a tumor poses a threat to an elderly patient's life.

  A technique called debulking uses any of the microsurgical approaches as the first step in a two step process. In case of regrowth, the surgery is followed up with a radiation treatment to arrest the tumor. Oftentimes it is used with large tumors when the goal would be to primarily preserve the facial nerve.

• Endoscopy

  Periodically questions surface about endoscopy and mention here should not be taken as an endorsement. This technique claims to be minimally invasive creating a dime-sized incision behind the ear. A leading center for this type of surgery is the Cedars-Sinai Skull Base Institute. Hrayr K. Shahinian, MD, the Director, is a trained plastic and reconstructive surgeon with fellowships in skull base surgery and in craniofacial surgery. Some criticism has been leveled against this doctor because he is not a trained neurosurgeon. Before choosing this treatment, much investigation should be done checking references and data. There has been conversation on the ANA listserv that did not instill confidence. Note that the Institute claims to have articles that have undergone peer review. Between 1998 and april 2004 they claim to have operated about 600 acoustic neuromas.

• Balance problems. Balance problems frequently occur with acoustic neuromas, both before and after treatment. These tumors are also called vestibular schwannomas because they arise from the sheath of the vestibular nerve which plays an important role in the body's balance system. It may be necessary to cut the vestibular nerve during surgery, or it can be damaged in the process of removing the tumor. In most cases balance problems will be temporary as other balance mechanisms in the body take over and compensate.
• CSF leaks. Cerebrospinal fluid, CSF, circulates around the brain and spinal cord as the name suggests. It is constantly produced and recirculated. If it's flow is inhibited excess pressure on the brain can result (see 'hydrocephalus' below). Following open skull surgery there can be, in less than 5% of cases, leaks of CSF, through the nose or the ears or, in rare cases, from the surgical incision. If they do occur, a second operation may be necessary to stop the leak.
• Death. Death on the operating table, or as a direct result of the operation, is no longer a major problem. Improvements in surgical technique over the last 30 years have an enormous difference in the likelihood of operating mortality for acoustic neuroma patients. It is estimated now that less than 1% of AN patients treated by competent surgeons will die as a result of the operation.
• Inability to close eyelid, dry eye, double vision. The eye may become dry and unprotected, should facial paralysis develop. It might be necessary to apply artificial tears or to tape the eye shut. In some cases, surgery on the eyelid is necessary.
• Weakness of the face Because the acoustic tumors are in intimate contact with the facial nerve, temporary weakness of the face due to nerve swelling is common. Facial weakness may last for six months to a year. In some cases there may be permanent facial weakness. According to HEI, in 1-2% of the cases it is necessary to remove all or a portion of the facial nerve in order to remove the tumor. In some instances it is possible to reconnect the facial nerve during the surgery. When it is not possible to repair the facial nerve during the surgery, a further surgery may be necessary to substitute another nerve. In 1985 a scale called the House Brackmann Scale was developed to rate the degrees of facial weakness. It is the most commonly used scale to date.
• Facial pain, numbness. . See facial weakness
• Taste and swallowing problems. . It is not uncommon to experience dry mouth and taste disturbance for a few weeks following surgery. In some cases the duration is prolonged.
• Headaches. As mentioned above it is also reported there is a �10% incidence of severe postoperative headaches with the retrosigmoid approach.
• Hearing loss. Hearing loss varies depending on the type of surgical approach. Translab always results in hearing loss. With the others there are prognostic factors that give some predictive outcome. Tumor size is not necessarily a predictor. Tumors originating from the superior vestibular nerve have a greater chance of hearing preservation than those arising from the inferior vestibular nerve. Those that do not extend all the way to the end of the internal auditory canal are more favorable for hearing preservation. Better preoperative hearing in general correlates with hearing preservation. Preoperative audiometric brainstem response testing data is of value with shorter intr-aural wave and absolute V latencies related to ncresed probable hearing preservation. House Ear Institute states that 20-30% of patients develop total hearing loss in the operated ear.
• Hydrocephalus. (1) - A small percentage of patients (the same percentage as for radiation) will suffer from hydrocephalus.  This is cured by a simple operation to place a "shunt" which relieves the excess pressure by draining the fluid.
• Meningitis. (2) - House Ear Institute states that infection occurs in less than 5% of the patients following surgery. Should this develop, it could lead to meningitis, an infection of the fluid and tissue surroundng the brain. This would require an extended hospital stay.
• Regrowth of the tumor. more to come ...
• Seizures, strokes. more to come ...
• Tinnitus. (3) - Head noise, commonly called tinnutis, typically remains the same as before surgery. If it develops prior to surgery, it usually is present after surgery. If hearing worsens after surgery, there may be an increase in tinnutis afterward.

LINKS

• www.anausa.org The Acoustic Neuroma Association (USA). There is a lot of useful information on this site and a guest book as well as a very active mailing list for patients.
• http://www.houseearclinic.com/acousticneuroma.htm House Ear Clinic is recognized as an institution having treated over 5,000 cases of AN. They provide free consultations with a doctor. Send your MRI and audiogram results to:
    Acoustic Neuroma Website Consultations
    2100 W. Third Street, 1st floor
    Los Angeles, CA 90057
  Audiovisual presentation by Rick Friedman MD, 2003
• http://www.michiganear.com/procedures/acoustic-neuromaThe Michigan Ear Institute
• The Journal of Neurosurgery Often contains interesting articles on acoustic neuroma surgery.

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