Management of Acoustic
File 4: Management
G. OJEMANN, M.D.
© Congress of Neurological Surgeons
Honored Guest Presentation
Originally Published Clinical Neurosurgery, Volume 40, Chapter
24, Pages 498-535, 1992
Used with permission of the Congress of Neurological Surgeons.
HTML Editor: Stephen
B. Tatter, M.D., Ph.D.
The information and reference materials contained herein are intended
solely to provide background information. They were written for an
audience of physicians. They are in no way intended to constitute
medical advise. For medical advise a physician must, of course, be
- INTRODUCTION (File
- SURGICAL MANAGEMENT (For surgeons!,
- Perioperative Medical Therapy
- Incision and Exposure
- Removal of Small Tumors and
- Removal of Medium and Large
- Management of Postoperative
- Hematoma and Cerebellar
- Cerebrospinal Fluid Fistula
- Wound Infection
- Neurological Complications
- RESULTS OF SUBOCCIPITAL OPERATION:
Summary of the Series, 1979-1992 (File
- Extent of Tumor Removal and
- Postoperative Complications
- Cochlear Nerve Function
- Management of Tumor in the Only
- Management in Elderly Patients
(70 Years and Older)
- Management in Patients with
MANAGEMENT (This File)
MANAGEMENT (This File)
- MANAGEMENT PLAN
| FIG-24.13: Indication
for operation. This 20-year-old woman had transient vertigo
while figure skating. Mild hearing loss was noted in her left
ear and she developed frontal headaches. The MRI axial Tl image
after gadolinium showed a large tumor consistent with an acoustic
neuroma. Total removal was done. Facial nerve function was grade
3. She was able to resume figure skating.
| FIG-24.14: Indication
for operation. This 52-year-old man had decreased hearing
in his left ear for >1 year and increased numbness on the
left side of his face for 2 months. The MRI axial TI image showed
anterior growth of the tumor. Total removal was followed by
full recovery and normal facial nerve function.
In 1971 Leksell (20) reported the
first use of stereotactic radiosurgery to treat a patient with an
acoustic neuroma. Subsequently, further experience was reported
(34). Detailed and comprehensive follow-up reports have been published
by Lunsford and his group (26); summarizing the experience at the
University of Pittsburgh, which had the first North American 201-source
611C gamma unit. Reports from both these groups show a high rate
of tumor growth control and an acceptable rate of complications.
These facts have established stereotactic radiosurgery as one of
the three treatment alternatives to consider in a patient with an
In January 1992 the results for 74
patients with unilateral acoustic neuromas were reported by the
Pittsburgh Group. There was no mortality and all returned to their
previous level of activity in 5-7 days. The followup ranged from
3 to 36 months, and two tumors (3%) were larger, 54 (73%) were the
same, and IS (24%) were smaller. The measurement error was estimated
to be ±1.3 mm, and a change of ±2.6 nun was required to categorize
the change as smaller or larger. The two patients with larger tumors
had no new symptoms and are being observed.
In the same report, of 70 patients
with normal preoperative facial nerve function 24 (34%) developed
a delayed facial nerve weakness. At the time of follow-up, 13 of
the 24 had made a good recovery (six grade 1 and seven grade 2),
leaving 11 of the 70 (16%) with grade 3 or worse. This complication
could not be correlated with tumor size or any of the radiation
dosage parameters. The preservation of useful hearing, as deflned
by at least a 50% SDS and pure tone average of 50 db or less, was
38% at 1 year. This could not be statistically correlated with tumor
size. However, it was also noted that of 13 patients with tumors
of <1.0-cm diameter none had lost useful hearing. Of 66 patients
with normal preoperative trigeminal nerve function 32% developed
delayed trigeminal neuropathy. In those with abnormal function it
was 46%. Only 10% had resolved completely at follow-up but most
seemed to be improving. A significant correlation between radiation
dose and delayed cranial neuropathies could not be demonstrated.
Other persistent problems included
worsened balance in 20-30% and a small percentage of patients with
dizziness or vertigo, persistent nausea, and worsened headaches.
Eight patients developed new parenchymal changes in the middle cerebellar
peduncle and pons on MRI scans. No associated symptoms were noted,
and these changes tended to resolve. Four patients required ventriculoperitoneal
shunt 5-16 months after radiosurgery. The cause of the hydrocephalus
was thought possibly to be elevated cerebrospinal fluid protein
Other types of radiation therapy have
also been reported to have a beneficial effect on an acoustic neuroma.
These include fractionated conventional therapy, proton beam therapy,
and radiosurgery using the linear accelerator (6, 57).
| FIG-24.15: Indication
for operation. This 45-year-old man reported increasing
difficulty hearing over the telephone with his left ear, for
several months. The MRI axial TI image after gadolinium showed
a small tumor projecting about 1.0 cm into the posterior fossa.
The audiogram showed useful hearing with a SDS of 60%. Total
removal was done, with preservation of hearing and facial nerve
Acoustic neuromas usually enlarge
slowly. However, it has been well documented that some tumors stop
growing, that spontaneous regression may occasionally occur, and
that a rare tumor may unexpectedly grow rapidly (2, 32, 56). Bederson
et al. (2) reported 70 patients who were initially observed because
they did not want surgery or did not have progressive symptoms.
The average follow-up was 36 months (range, 6-84 months). During
the first year 29 patients (41%) had no detectable tumor growth
and, of 18 who had a second-year scan, only one showed detectable
growth. In 37 patients (53%) growth ranging from I to 17 mm (average,
3.4 ± 0.5 mm) occurred during the first year and, of 23 patients
with a second-year follow-up scan, 21
showed further growth. In four patients
(6%) there was regression in tumor size. Rapid growth rate in seven
and clinical deterioration in two other patients without change in
the size of the tumor led to surgical intervention. There was no relationship
of tumor growth to age, duration of symptoms, or initial tumor size.
Another study also documented that there was no correlation between
tumor growth and the patient's age and that, over a period of 8 months
to >4 years, 50% showed no change (56). The true incidence of cessation
of growth is unknown since these were selected patients, many of whom
had stable symptoms.
| FIG-24.16: Indication
for operation or radiation therapy. This 68-year-old woman
had a history of progressive hearing loss in her right ear for
2 years and problems with balance and lightheartedness for 1
year. The MRI axial TI image after gadolinium (A) showed
a 1.5cm tumor consistent with an acoustic neuroma. She was initially
observed. MRI 6 months later (B) showed enlargement of
the tumor. After being presented with the treatment options,
she asked to have the tumor removed. She made a full recovery
with normal facial nerve function. Radiation therapy would have
been an acceptable alternative.
With the increasing information available
in the literature regarding the three management options, surgery,
radiotherapy, and observation, the physician caring for these patients
can begin to make informed recommendations.
First, physicians must take the patient's
history themselves to have a clear idea of the course of the disease
and how the symptoms are affecting the patient's life. An objective
assessment of any neurological deficit should be made. Radiographic
studies should be carefully reviewed to be sure they are adequate
and a decision should be made regarding whether any additional studies
In some patients there is little doubt
as to what should be done.
In other patients the decision may be
difficult (40). To arrive at a decision the physician must have up-to-date
knowledge about the natural history and treatment alternatives. With
this information the physician can then weigh the management options.
What will be the impact on the patient's daily life? Will the treatment
improve or arrest the progression of symptoms? Can further growth
or recurrence of the tumor be prevented? What are the risks of the
treatment? Do the short- and long-term benefits justify these risks?
It is important to discuss with patients their hopes and expectations
regarding the treatment.
| FIG-24.17: Indication
for operation or radiation therapy. This 72-year-old man
had progressive hearing loss. The MRI axial TI image after gadolinium
(A) showed a 1.0-cm tumor. He was observed and there
was no change for I year. However, the MRI scan (B) at
18 months showed definite enlargement. He was treated with radiosurgery.
Surgery would have been an acceptable alternative.
Several factors are considered when
making the treatment recommendation. These include the history and
findings, age of the patient, size of the tumor, the patient's overall
clinical condition, and the expected benefits and risks of the treatment
options. It is not practical to defme a specific age which influences
the decision to operate, observe the patient, or use radiotherapy.
However, in the older patient a clinical judgment is made based
on these factors.
My indications for operation are as
- Recent or worsening symptoms, except
for elderly patients with mild symptoms (Figs. 24.13 and 24.14).
With small tumors an attempt is made to preserve useful hearing
(Fig. 24.15). For large tumors radical subtotal or subtotal removal
is considered, especially in older patients, if there is adherence
(Figs. 24. 11 and 24.12).
- Enlargement of the tumor in patients
who are being observed (except some elderly patients) (Fig. 24.16).
- Regrowth after subtotal removal
when it is likely that a more extensive removal can be done.
- The patient's decision after discussion
of the treatment options (Fig. 24.16).
My indications for radiation therapy
are as follows.
- Enlarging small or medium size tumor
in an elderly patient with n-tild symptoms who is being observed
- Regrowth after subtotal removal
- Associated major medical illness.
- The patient's decision after discussion
of the treatment options.
| FIG-24.18: Indication
for radiation therapy. This 70-year-old woman had a history
of hearing loss in her right ear and increasing numbness on
her face. A subtotal removal of a large acoustic neuroma was
done. The residual tumor remained stable for 2 years, after
which it started to grow. MRI TI axial (A) and coronal (B)
images after gadolinium showed the size and configuration
of the tumor. Fractional radiation therapy was given, with arrest
of the growth.
My indications for observation are
- A long history of auditory symptoms
in patient of any age with any size tumor (Fig. 24.19).
- An elderly patient with rnild symptoms
- An incidental finding of the tumor
on a scan done for some other reason.
- The patient's decision after discussion
of the treatment options.
The outlook for a patient with an
acoustic neuroma is markedly improved over what it was when I saw
my first patient with this tumor in 1957. There is every expectation
that advances will continue for the benefit of these patients.
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Morrison, A. W. Hearing conservation in acoustic neuroma surgery
via the posterior fossa. J. Laryngol. Otol., 104: 463-467, 1990.
- Bederson, J. B., von Ammon, K.,
Wichmann, W. W., el al. Conservative treatment of patients with
acoustic neuroma. Neurosurgery, 28: 646-651, 1991.
| FIG-24.19: Indication
for observation. This patient was first seen at age
55 with a history of sudden loss of hearing in his left
ear 9 years previously. There was intermittent facial numbness.
He was fully active and ran 50 miles per week. There were
no abnormalities except the hearing loss on neurological
examination. CT scan showed a large cerebellopontine angle
tumor consistent with an acoustic neuroma. Because of the
long history of stable symptoms, he was observed. The MRI
axial TI image after gadolinium 9 years later, shown here,
revealed no change in the size of the tumor and there are
no new symptoms.
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for acoustic tumor removal. Otolaryngol. Clin. North Am., 25:
- Cohen, N. J., Berg, H., Hammerschlag,
R., et al. Acoustic neuroma surgery: an eclectic approach
with emphasis on preservation of hearing. Ann. Otol. Rhinol. Laryngol.,
- Compton, J. S., Bordi, L. T., Cheeseman,
A. D., et al. The small acoustic neuroma: a chance to preserve
hearing. Acta NeurocWr. (Wien.), 98: 115-117, 1989.
- Darrouzet, V., Maire, J. B., Flocquet,
A., el al. Irradiation of neurinoma: why? how? first results.
Rev. Laryngol. Otol. Rhinol. (Bard), 111: 211-215,1990.
- Davis, K. R., Parker, S. W., New,
P. F., el al. Computed tomography of acoustic neuroma.
Radiology, 124: 81-86,1977.
- Ebersold, M. J., Harner, S. G.,
Bentty, C. W., et al. Current results of retrosigmoid approach
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J. Hearing preservation in acoustic neuroma surgery. J. Neurosurg.,
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Hearing preservation in unilateral acoustic neuroma surgery. Ann.
Otol. Rhinol. Laryngol., 97: 55-66, 1988.
- Harner, S. G., Beatty, C. W., and
Ebersold, M. J. Retrosigmod removal of acoustic neuroma: experience
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| FIG-24.20: Indication
for observation. This 76-year-old man presented with
a 1 year history of progressive hearing loss in his left
ear. This was of little concern to him. The MRI axial TI
image after gadolinium shows findings consistent with a
small acoustic neuroma that is being followed and has not
changed in size.
- Martuza, R. J., Parker, S. W., Nadol,
J. B., Jr., et al. Diagnosis of cerebellopontine angle
tumors. Clin. Neurosurg., 32: 177-213, 1985.
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R. G., et al. Long-term hearing results in patients after
surgical removal of acoustic tumors with hearing preservation.
Am. J. Otol., 13: 134-136,1992.
- Nadol, J. B., Jr., Chiong, C. M.,
Ojemann, R. G., et al. Preservation of hearing and facial
nerve function in resection of acoustic neuroma. Laryngoscope,
102: 1153-1158, 1992.
- Nadol, J. B., Jr., Levine, P. A.,
Ojemann, R. G., et al. Preservation of hearing in surgical
removal of acoustic neuromas of the internal auditory canal and
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Kassel, E. F., et al. Is no treatment good treatment in
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