ACOUSTIC NEUROMA

Acoustic NeuromaAcoustic NeuromaThe ear anatomy and auditory

pathway.What is Acoustic neuroma?

How does the tumor develop?The tumors growth.

Symptoms.What causes acoustic neuroma?What are the different types of

acoustic neuroma?Diagnosis.Treatment.Prognosis.Conclusion.

AnatoAnatomymy

utricleutricle

sacculesaccule

Semicircular canals Semicircular canals

What is Acoustic What is Acoustic Neuroma?Neuroma?

An acoustic An acoustic neuroma is a neuroma is a

benign tumor on benign tumor on the the

vestibulocochlear vestibulocochlear nerve (eighth nerve (eighth

cranial nerve).cranial nerve).

Alternative names:Alternative names: Vestibular schwannoma. Vestibular schwannoma. Tumor – acoustic. Tumor – acoustic. Cerebellopontine angle tumor. Cerebellopontine angle tumor. Angle tumor. Angle tumor. acoustic neurinoma.acoustic neurinoma.

How does the How does the tumor developtumor develop?? The vestibular nerve, like The vestibular nerve, like

many nerves, is many nerves, is surrounded by a cover surrounded by a cover called a myelin sheath called a myelin sheath which is formed by a which is formed by a

schwann cell. schwann cell. A tumor sometimes A tumor sometimes

develops from develops from Overproduction of the Overproduction of the myelin sheath of the myelin sheath of the

Schwann cellsSchwann cells, called a , called a schwannoma.schwannoma.

Acoustic neuroma can occur anywhere Acoustic neuroma can occur anywhere along the vestibular nerve but are most along the vestibular nerve but are most

likely to occur where the likely to occur where the vestibulocochlear nerve passes through vestibulocochlear nerve passes through

the internal auditory canal.the internal auditory canal.

The The tumor tumor growthgrowth

Acoustic Acoustic neuromas neuromas

range in size range in size up to 4 cm. up to 4 cm. 

stage I:stage I: it's called it's called intracanalicular intracanalicular tumor and tumor and measured in measured in millimeters. millimeters. It slowly fill the It slowly fill the IAC... IAC...

In Stage II:In Stage II:a "small“ acoustic a "small“ acoustic less than 1.5 cm less than 1.5 cm and called cisternal and called cisternal tumor protrude tumor protrude through the through the opening of the IAC opening of the IAC on the brain side, on the brain side, into the into the CerebellopontineCerebellopontineangle (CPA).angle (CPA).

In Stage III:In Stage III: A "moderate" A "moderate" acoustic about 1.5 to acoustic about 1.5 to 3 cm called 3 cm called compressive tumor compressive tumor has grown to come has grown to come into contact with the into contact with the cerebellum and/or cerebellum and/or the brainstem, the brainstem, without without compressing these compressing these brain structures...brain structures...

Finally in Stage Finally in Stage IV:IV: if untreated a if untreated a "large" acoustic "large" acoustic about 3 cm or about 3 cm or greater will greater will deform the deform the cerebellum and/or cerebellum and/or the brainstem...the brainstem...

symptomssymptomsThe symptoms vary with the size and The symptoms vary with the size and location of the tumor. location of the tumor.

Some acoustic neuromas remain so Some acoustic neuromas remain so small that they do not cause any small that they do not cause any symptoms. symptoms.

As the acoustic neuroma grows it can As the acoustic neuroma grows it can affectaffect::

The vestibular nerve causing vertigo and The vestibular nerve causing vertigo and balance difficulties (disequilibrium)…balance difficulties (disequilibrium)…

The cochlear nerve causing hearing loss The cochlear nerve causing hearing loss and tinnitus in the affected ear…and tinnitus in the affected ear…

As the acoustic neuroma grows it can As the acoustic neuroma grows it can affectaffect::

The surrounding cranial nerves. The surrounding cranial nerves. i.i. 55thth CN CN results in facial pain and or results in facial pain and or

numbness.numbness.ii.ii. 66thth CN causing double vision… CN causing double vision…iii.iii. 77thth CN causing spasms, weakness or CN causing spasms, weakness or

paralysis of the facial muscles. paralysis of the facial muscles. iv.iv. 99thth, 10, 10thth, or 12, or 12thth CN resulting in CN resulting in

swallowing and/or speaking swallowing and/or speaking difficulties.difficulties.

As the acoustic neuroma grows it can As the acoustic neuroma grows it can affectaffect::

If left untreated, the tumor can If left untreated, the tumor can become large enough to press against become large enough to press against and affect the functioning of the brain and affect the functioning of the brain stem… Causing:stem… Causing:

i.i. Headaches. Headaches. ii.ii. Gait ataxia… Gait ataxia… iii.iii. Tremors… Tremors… iv.iv. Nausea or vomiting. Nausea or vomiting.

v.v. Sleepiness. Sleepiness. vi.vi. Coma. Coma. vii.vii.Respiratory Respiratory

difficultiesdifficultiesviii.viii.Death.Death.

What cause acoustic What cause acoustic neuromaneuroma??

These tumors are thought to arise when These tumors are thought to arise when there is a defect in a certain tumor there is a defect in a certain tumor suppressor gene, which normally suppressor gene, which normally

prevents tumors from occurring…prevents tumors from occurring…

Acoustic neuromas are relatively Acoustic neuromas are relatively uncommon, but they are one of the most uncommon, but they are one of the most

common types of brain tumors. common types of brain tumors.

Acoustic neuroma occurs in two Acoustic neuroma occurs in two forms: forms:

1. A sporadic form which account for 95% of all cases. The cause of the sporadic form is unclear.

2. A form associated with an inherited syndrome called neurofibromatosis type II (NF2). Roughly 5% of patients with acoustic neuroma have NF2.

What are the differentWhat are the different types of acoustic types of acoustic

neurinoma?neurinoma? Unilateral acoustic neurinomas:Unilateral acoustic neurinomas: Account for 8 percent of all tumors inside Account for 8 percent of all tumors inside

the skull.the skull. May develop at any age, but most often May develop at any age, but most often

occur between the ages of 30 and 60.occur between the ages of 30 and 60. May be the result of gene damage caused May be the result of gene damage caused

by environmental factors. by environmental factors. Most unilateral acoustic neuromas result Most unilateral acoustic neuromas result

when the genes, that are responsible for when the genes, that are responsible for the prevention of tumors, become the prevention of tumors, become spontaneouslyspontaneously changed or missing. changed or missing.

What are the differentWhat are the different types of acoustic types of acoustic

neurinoma?neurinoma?

Bilateral acoustic neurinomas Bilateral acoustic neurinomas Develop in the teens or early adulthood. Develop in the teens or early adulthood. Are hereditary, caused by Are hereditary, caused by

neurofibromatosis-2 (NF2)…neurofibromatosis-2 (NF2)…

DiagnosisDiagnosis The health care provider may The health care provider may diagnose an acoustic neuroma based diagnose an acoustic neuroma based on the history, neurological on the history, neurological examination or testing of the examination or testing of the patient. patient.

First:First: PHYSICAL PHYSICAL EXAMINATION…EXAMINATION…

Second:Second: Pure tone and speech Pure tone and speech audiometryaudiometry……

Third:Third: auditory brainstem auditory brainstem response (ABR)response (ABR)……

Wave I: Action potential, Wave I: Action potential, close to the cochlea.close to the cochlea.

Wave II: Away from the Wave II: Away from the cochlea.cochlea.

Wave III: Cochlear nucleus.Wave III: Cochlear nucleus.

Wave IV: Superior olive.Wave IV: Superior olive.

V: Inferior colliculus V: Inferior colliculus

Fourth:Fourth: Magnetic resonance Magnetic resonance imaging (MRI)…imaging (MRI)…

Other useful tests used to diagnose acoustic Other useful tests used to diagnose acoustic neuroma and to differentiate it from other neuroma and to differentiate it from other

causes of dizziness or vertigo include:causes of dizziness or vertigo include:

CT CT scan… scan… caloric stimulation…caloric stimulation… Electronystagmography…Electronystagmography…

TreatmTreatmentent

There are five distinct treatment There are five distinct treatment options: options:

Medical treatment or observationMedical treatment or observationSurgerySurgeryradiation radiation Gamma-knife procedure Gamma-knife procedure Cochlear implantation Cochlear implantation

11--ObservationObservation About 25% of all acoustic neuromas are treated About 25% of all acoustic neuromas are treated

with medical management. Medical management with medical management. Medical management consists of: consists of:

Periodic monitoring of the patient's neurological status. Periodic monitoring of the patient's neurological status. Use of hearing aids when appropriate. Use of hearing aids when appropriate. Periodic imaging studies. Periodic imaging studies.

Since these tumors usually grow very slowly,Since these tumors usually grow very slowly, about about 1- 1/2 mm per year, 1- 1/2 mm per year, small tumors that have small tumors that have minimal or no symptoms can be safely observed minimal or no symptoms can be safely observed with regular MRI scans and left untreated unless with regular MRI scans and left untreated unless they grow dangerously.they grow dangerously.

Once a tumor is diagnosed, a repeat scan is Once a tumor is diagnosed, a repeat scan is obtained at six months and then at yearly intervals.obtained at six months and then at yearly intervals.

This procedure has its own risks… This procedure has its own risks…

2-Microsurgery 2-Microsurgery The surgical removal of the tumor or tumors is The surgical removal of the tumor or tumors is

the most common treatment for acoustic the most common treatment for acoustic neuroma… neuroma…

In most cases the entire tumor is removed In most cases the entire tumor is removed during the surgery. during the surgery.

If the tumor is large and causing significant If the tumor is large and causing significant symptoms then only part of the tumor may be symptoms then only part of the tumor may be removed to prevent hearing. removed to prevent hearing.

Monitoring of the neighboring cranial nerves Monitoring of the neighboring cranial nerves is done during the procedure so that damage to is done during the procedure so that damage to these nerves can be prevented.these nerves can be prevented.

MRIs are usually obtained at 1 and 5 years to MRIs are usually obtained at 1 and 5 years to detect residual or recurrent tumor. detect residual or recurrent tumor.

MicrosurgeryMicrosurgery22--Surgical complications:Surgical complications:

Most people experience fatigue and head discomfort Most people experience fatigue and head discomfort following the surgery. following the surgery.

Problems with balance. Problems with balance. Head and neck stiffness are also common.Head and neck stiffness are also common.

Approximately 20% of patients experience some Approximately 20% of patients experience some degree of post-surgical complications… degree of post-surgical complications…

Surgery brings with it a risk of stroke, damage to the Surgery brings with it a risk of stroke, damage to the brain stem, infection, leakage of spinal fluid and brain stem, infection, leakage of spinal fluid and damage to the cranial nerves. damage to the cranial nerves.

Hearing loss and/or tinnitus often result from the Hearing loss and/or tinnitus often result from the surgery. surgery.

Significant headache can occur following acoustic Significant headache can occur following acoustic neuroma surgery with an incidence of about 20%. neuroma surgery with an incidence of about 20%.

Pre and post Pre and post operational operational

teststests

33--Stereotactic RadiosurgeryStereotactic Radiosurgery The goal of radiation therapy is to slow or stop the The goal of radiation therapy is to slow or stop the

tumor growth, not to cure or remove the tumor.tumor growth, not to cure or remove the tumor.

Radiosurgery is often performed in elderly or sick Radiosurgery is often performed in elderly or sick patients who are unable to tolerate brain surgery.patients who are unable to tolerate brain surgery.

Sometimes during brain surgery to treat acoustic Sometimes during brain surgery to treat acoustic neuromas, not all of the tumor can be safely removed, neuromas, not all of the tumor can be safely removed, and some residual tumor must be left behind. and some residual tumor must be left behind. Radiosurgery is often used post-operatively to treat Radiosurgery is often used post-operatively to treat residual tumor in these cases. residual tumor in these cases.

Radiosurgery is only appropriate for small tumors, so Radiosurgery is only appropriate for small tumors, so that radiation damage to surrounding tissues can be that radiation damage to surrounding tissues can be minimized.minimized.

Like brain surgery, radiosurgery can sometimes result Like brain surgery, radiosurgery can sometimes result in facial paralysis or loss of hearing. in facial paralysis or loss of hearing.

44--Gamma KnifeGamma KnifeWhen the risk of surgery is high because of other When the risk of surgery is high because of other

medical problems, or where the patient simply medical problems, or where the patient simply refuses surgery, the gamma knife procedure may be refuses surgery, the gamma knife procedure may be used.used.

This option is usually recommended only for high-This option is usually recommended only for high-risk surgical cases because of the possibilities of late risk surgical cases because of the possibilities of late radiation complications, hydrocephalus (in about radiation complications, hydrocephalus (in about 10% of patients), and the need for ongoing MRI 10% of patients), and the need for ongoing MRI monitoring of the results of the procedure. monitoring of the results of the procedure.

Patients are best followed with periodic MRI scans Patients are best followed with periodic MRI scans for the remainder of their lives. The recurrence rate for the remainder of their lives. The recurrence rate of the tumor is about 3% after surgery, and 14% of the tumor is about 3% after surgery, and 14% after gamma knife.after gamma knife.

44--Gamma KnifeGamma KnifeGamma knife does not generally make Gamma knife does not generally make

tumors go away. tumors go away. If surgery is eventually required, surgical If surgery is eventually required, surgical

complications in this situation, such as complications in this situation, such as severe facial nerve weakness, are nearly severe facial nerve weakness, are nearly 100%...100%...

hearing loss is common after gamma knife. hearing loss is common after gamma knife. Delayed facial weakness, and facial Delayed facial weakness, and facial

numbness… numbness… Hydrocephalus…Hydrocephalus…Dysequilibrium…Dysequilibrium…

55--Cochlear ImplantationCochlear Implantation

Very rarely, a person with acoustic neuroma Very rarely, a person with acoustic neuroma might desire a cochlear implant. This might might desire a cochlear implant. This might occur if an acoustic tumor is present in the occur if an acoustic tumor is present in the

only hearing ear, or after surgery to remove only hearing ear, or after surgery to remove bilateral acoustic neuromas. Cochlear bilateral acoustic neuromas. Cochlear

implantation is possible only if there is an implantation is possible only if there is an intact cochlear nerve, and if the implantation intact cochlear nerve, and if the implantation is done at the time of acoustic tumor removal, is done at the time of acoustic tumor removal,

before the cochlea ossifies (turns to bone).before the cochlea ossifies (turns to bone).

PrognosisPrognosis The prognosis for someone with a unilateral The prognosis for someone with a unilateral

acoustic neuroma is usually quite good provided acoustic neuroma is usually quite good provided the tumor is diagnosed early and appropriate the tumor is diagnosed early and appropriate treatment is instituted.treatment is instituted.

Long term hearing loss and tinnitus in the Long term hearing loss and tinnitus in the affected ear are common, even if appropriate affected ear are common, even if appropriate treatment is provided. treatment is provided.

Regrowth of the tumor is also a possibility Regrowth of the tumor is also a possibility following surgery or radiation therapy and following surgery or radiation therapy and repeat treatment may be necessary.repeat treatment may be necessary.

The prognosis can be poorer for those with NF2 The prognosis can be poorer for those with NF2 who have an increased risk of bilateral acoustic who have an increased risk of bilateral acoustic neuromas and other tumors.neuromas and other tumors.

ConclusiConclusionon

Microsurgical technique, lasers and the use of Microsurgical technique, lasers and the use of facial nerve monitoring have dramatically facial nerve monitoring have dramatically improved the safety of removing acoustic improved the safety of removing acoustic tumors.tumors.

There is no one best approach. Each case There is no one best approach. Each case needs to be looked at individually.needs to be looked at individually.

Hopefully, this presentation has made the Hopefully, this presentation has made the topic a bit more understandable.topic a bit more understandable.