Download Acoustic Neuroma Report Final

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Rachel Johnson
Dr. Candland Asplund
English 2010
March 2, 2015
Acoustic Neuroma
Acoustic neuromas are not new to the medical field, unless you have been unlucky
enough to be diagnosed with such a brain tumor, or are in the medical field, you likely have never heard of it. The effects brain tumors, such as acoustic neuromas, have on patients and the
treatment options available are varied. The question remains: what is an acoustic neuroma, what
are the treatments and what is its impact?
Acoustic neuromas are diagnosed in 2,000 to 3,000 people annually, or approximately 1
in 100,000 people per year. (Johns Hopkins) An acoustic neuroma is a benign (non-cancerous)
vestibular schwannoma, which is caused by an, “overproliferation [growth] of “schwann cells”
constituting the 8th cranial nerve sheath.” (Skull Base Institute) The 8th cranial nerve is the vestibulocochlear (balance & hearing) nerve, which is responsible for two things: “transmitting
sound and sending balance information to the brain from the inner ear.” (Skull Base Institute)
The 8th cranial nerve lies alongside the 7th cranial nerve (facial nerve) within the internal auditory canal (approximately 2 cm long), which leads into the brainstem. (McKinley, O’Laughlin,
Pennefather-O’Brien and Harris) Many incorrect assumptions are made that because it is a benign tumor and it’s housed within the internal auditory canal it is not in fact a “brain tumor”. It is
a brain tumor because it arises from a cranial nerve and if left alone, it will “expand at its
origin… ultimately displacing brain tissue,” pushing the brainstem - which regulates heart rate,
breathing and blood pressure - out of the way, becoming fatal if left untreated.
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People often think that an acoustic neuroma is relatively new to the medical world when
they first hear of it, but this is not the case. The first description of what is now known as an
acoustic neuroma was found in 1777 in a post mortem examination done in Leydon, Germany.
(Glassock) This first description was accurate, and gave the medical field information about the
pathology, but lacked in clinical symptoms. In 1810, Leveque-Lasource linked clinical symptoms with the post-mortem findings. (Glassock) As you may guess, the first surgery to remove
an acoustic neuroma followed many years later. Surprisingly the first attempt to surgically resect
an acoustic neuroma happened in 1894 by Sir Charles Balance. (Kaylie, McMenomey)
What are the symptoms of an acoustic neuroma, which would lead to a diagnosis? In
90% of the cases, the first symptom of an acoustic neuroma is uni-lateral (one-sided) hearing
loss. (Johns Hopkins) Another symptom often accompanying hearing loss is tinnitus, described
as “hissing, ringing, buzzing or roaring” in the ear. (Johns Hopkins) As the location of an acoustic neuroma is found on the vesitbulocochlear nerve, vertigo is commonly experienced by those
with smaller tumors rather than large tumors, assuming that, as the tumor grows, it destroys the
vestibular (balance) nerve. (Johns Hopkins) Often, unexplained headaches are recalled after diagnosis of acoustic neuromas. (ANA) Finally and most rare, is facial weakness, numbness and
pain associated with large acoustic neuromas that have begun to either press on the facial nerve
within the internal auditory canal or the trigeminal nerve within the brain cavity. (Johns Hopkins) There are three treatment options available for acoustic neuromas. The choice of treatment
is based on the individual patient. In my particular case, I had perfect hearing, no tinnitus and
extreme vertigo before diagnosis of my relatively small tumor.
The first option available is observation, or watch and wait. Typically, elderly patients
choose observation, if they have a small tumor size, their hearing is intact, other medical condi-
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tions would increase risk of surgery or patients refuse treatment. (Kutz) Observation is followed
closely by yearly MRI scans to determine the size of the tumor and if radiation therapy or surgical therapy is necessary. (ANA) This lack of treatment clearly does not address the symptoms of
the patient or prevention of growth of the tumor and further damage. Depending upon the age of
the patient, it may result in surgical excision of the tumor, which only extends the duration of
symptoms and recovery and can result in other potential risks associated with removing a larger
tumor.
Radiation therapy or stereotactic radiotherapy, is the second available option for patients
with an acoustic neuroma. Radiation is “delivered to a precise point or series of points to maximize the amount of radiation delivered to target tissues while minimizing the exposure of adjacent normal tissues. It can be delivered as a single dose or as multiple fractionated doses.” (Kutz)
The purpose of using radiation is to arrest the development of the tumor. The disadvantages of
radiation include constant follow-up, as the tumor is not removed, but rather stops growing while
still causing symptoms of the tumor. There is a small chance of the tumor becoming cancerous (1
in 1,000 patients over 30 years) and there is a higher rate of damage to the trigeminal nerve.
(Kutz) Additionally the long-term effect of radiation beyond five years is unknown. (Johns
Hopkins)
The final option is microsurgical resection (removal) of the tumor through three different
approaches. Each approach is determined by size and location of tumor, and whether hearing
preservation is desired. A retrosigmoid approach gives the surgeon a wide field of view with the
ability to preserve hearing, unless it is a small tumor that is closer to inner ear. (Kutz) There is an
increased risk of cerebrospinal fluid leak and a higher incidence of recurrence. (Kutz) The translabyrinthine approach is used for large tumors without the need for hearing preservation, giving a
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full view of the brainstem with less risk to the facial nerve. (Kutz) If the patient has not already
lost all hearing, this approach is more widely used. Additionally, there are potential injuries to
cranial sinuses (blood flow and spinal fluid). (Kutz) The last surgical approach is the middlefossa approach, which is most used for small tumors, closest to the inner ear, with the goal of
hearing preservation. (Kutz) A potential risk involved in the middle fossa approach is damage to
the facial nerve. (Kutz)
As evidenced, treatment options are not an easy choice and should be weighed based on
age of the patient, overall patient health, size and location of the tumor and level of hearing.
Each treatment option has pros and cons associated it with it. In addition to different risks associated with each treatment, is the patient’s life after brain surgery and the potential side effects.
Balance issues after removal of the tumor when the balance nerve has been cut (or removed) are
common. The balance nerve on the other side of the brain will eventually compensate (ANA).
There is a potential for cerebrospinal fluid leak through the nose or ears following surgery that, if
left untreated, could lead to infection and meningitis. (ANA) Facial pain or weakness (paralysis)
is a common complication from surgery, which often causes the inability to close the eye, which
also leads to double vision and dry eye. In addition to all of the possible outcomes from surgery
other risks include: headaches, hearing loss, tinnitus, hydrocephalus, regrowth of the tumor, and
seizures or strokes. (ANA)
Although knowledge of acoustic neuromas are not widely known, it is clear that it is anything but simple to diagnose, live with or treat. Acoustic neuroma symptoms and post-treatment
issues are often silent, leaving those who don’t experience it with a lack of understanding of how
it impacts those who have it. Each case is unique, and as such each treatment option and post
treatment experience will be different. The most important thing is to make the best medical de-
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cision for yourself, based on your individual circumstance and a clear understanding of each
available option.
Works Cited
“Acoustic Neuroma.” Skull Base Institute. n.d. Web. 1 March 2015.
Acoustic Neuroma Association, 2015. Web. 1 March 2015
Ford, Katrina MD, Tidy, Colin MD. “Acoustic Neuroma.” patient.co.uk, 27 June 2014. Web
1 March 2015.
Glassock, Michael E. III, MD. “History of the Diagnosis and Treatment of Acoustic
Neuroma” JAMA Otolarngology - Head and Neck Surgery Archives 88. (1968): 30.
Print. Web. 1 March 2015.
Johns Hopkins Medicine; “Acoustic Neuroma: Symptoms, Treatment” nd, Web. 2 March
2015.
Kaylie, David M. MD; McMenomey, Sean O. MD. “Microsurgery vs Gamma Knife Radiosurgery for the Treatment of Vestibular Schwannomas” Archives Otolaryngol Head Neck
Surgery 129 (2003): 903. Print. Web. 1 March 2015
Kutz Jr. Joe Walter, MD. “Acoustic Neuroma Treatment & Management” Medscape
(2015):
Web. 1 March 2015
McKinley, Michael P., O’Loughlin, Valerie Dean, Pennefather-O’Brien, Elizabeth, Harris,
Ronald T. Human Anatomy, Fourth Edition. Biol 2320, Salt Lake Community College.
McGraw-Hill Education 2014. Print.