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ACOUSTIC NEUROMA/ VESTIBULARSCHWANNOMA
Taotao, Krisha AnneTulagan, PreciousVallejo, Maria TheresaBSN041
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DEFINITION
Also called: Acoustic neurilemoma, Acousticneurinoma, Auditory tumor, Vestibular schwannoma
Acoustic neuroma is a non-cancerous tumor thatdevelops on the nerve that connects the ear to thebrain.
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DEFINITION
It is a benign primary intracranial tumor of themyelin-forming cells of the vestibulocochlear nerve(CN VIII).(Neuromais derived from Greek,meaning "nerve tumor".) The term "acoustic" is a
misnomer, as the tumor rarely arises from theacoustic (or cochlear) division of thevestibulocochlear nerve.
The correct medical term is vestibular
schwannoma, because it involves the vestibularportion of the 8th cranial nerve and it arises fromSchwann cells, which are responsible for the myelinsheath in the peripheral nervous system.
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WHATCAUSES VESTIBULAR SCHWANNOMA?
Vestibular Schwannoma is caused by anoverproduction of Schwann cells. Schwann cellswrap around nerve fibers to help support andinsulate nerves.
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PATHOPHYSIOLOGY
The usual tumor in the adult presents as a solitary tumor,originating in the nerve. It usually arises from the vestibularportion of the 8th nerve, just within the internal auditory canal.As the tumor grows, it usually extends into the posterior fossato occupy the angle between the cerebellum and the pons
(cerebellopontine angle). Because of its position, it may alsocompress the 5th, 7th, and less often, the 9th and 10th cranialnerves. Later, it may compress the pons and lateral medulla,causing obstruction of the cerebrospinal fluid and increasedintracranial pressure.
Schwannomas can occur in relation to other cranial nerves or
spinal nerve roots, resulting in radiculopathy or spinal cordcompression. Trigeminal neuromas are the second mostcommon form of schwannomas involving cranial nerves.Schwannomas of other cranial nerves are very rare.
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PATHOPHYSIOLOGY
It is a benign Schwann cell tumors affecting CN VIII.These tumors usually unilateral and cause hearingloss by compressing the cochlear nere or interferingwith blood supply to the nerve and cochlea. Other
neoplasm can affect hearing include meningiomasand metastatic brain tumors. The temporal bone isa common site of metastasis. Breast cancer matmetastasize to the middle ear and invade the
cochlea.
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PATHOPHYSIOLOGY
Acoustic neuromas may occur sporadically, or insome cases occur as part of von Recklinhausenneurofibromatosis, in which case the neuroma maytake on one of two forms.
In Neurofibromatosis type I, a schwannoma maysporadically involve the 8th nerve, usually in adult life,but may involve any other cranial nerve or the spinalroot. Bilateral acoustic neuromas are rare in this type.
In Neurofibromatosis type II, bilateral acousticneuromas are the hallmark and typically present beforethe age of 21. These tumors tend to involve the entireextent of the nerve and show a strong autosomaldominant inheritance. Incidence is about 5 to 10%.
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CLINICAL MANIFESTATIONS
Hearing Loss. ipsilateral sensorineural hearing loss/deafness
Tinnitus most often a unilateral high-pitched ringing, sometimes
a machinery-like roaring or hissing sound, like a steamkettle
Vertigo (spinning) disturbed sense of balance and altered gait
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CLINICAL MANIFESTATIONS
Facial sensory disturbances Numbness in the face
occurs only in large tumors (about 50 percent of those greaterthan 2 cm in size).
Facial weakness is uncommon.
Facial twitching also known as facial synkinesis or hemifacial spasm, occurs in
about 10 percent of patients.
Headache prior to surgery occurs in roughly 40 percent of those with
large tumors
Hyperventilation Induced Nystagmus little known physical sign that may be far more specific for
acoustic neuroma.
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DIAGNOSTIC STUDIES
Brain Imaging
The major neuroimaging techniques used in drug abuseresearch are positron emission tomography (PET),single photon emission computed tomography
(SPECT), and magnetic resonance imaging (MRI),along with electro-encephalography (EEG), an earliertechnique for monitoring brain activity.
Conventional Audiometry
most useful diagnostic test for acoustic neuroma.
most common abnormality is an asymmetrical high-frequency sensorineural hearing loss .
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DIAGNOSTIC STUDIES
Hearing test (audiology)
provides an evaluation of the sensitivity of a person'ssense of hearing and is most often performed by anaudiologist using an audiometer
ABR testing ABR, or Auditory brainstem response, is a test of the
hearing, from the ears to the brainstem that can beconducted without the cooperation of the patient.
It basically consists of playing sounds to the patient andrecording the electrical waves of the brain. It's generallysafe and painless.
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DIAGNOSTIC STUDIES
Electronystagmography( ENG) Testing
To measure involuntary eye movements, callednystagmus, in order to evaluate the function of thevestibular system and associated brain areas.
Test of equilibrium and balance
Brainstem auditory evoked response
Test of hearing and brainstem function
Caloric stimulation
Test for vertigo
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NURSING INTERVENTIONS
Check Vital signs
Obtain clients assessment of discomfort
Establish comfortable and well ventilated
environmentProvide comfort measures
Provide small frequent meal
Collaborate in treatment of underlyingcondition causing discomfort
Identify changes in pain characteristicsrequiring medical follow-ups
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NURSING INTERVENTIONS
Review laboratory results related tocausative factors
Administer analgesic as needed
Be a sources and strengths of informationgiven to the patient
Provided from the peer-reviewed medical
literature which is the most reliable forpatient education
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MEDICAL INTERVENTIONS
Gamma Knife procedure
invented by Lars Leksell in 1971
method of irradiating the tumor
this procedure avoids surgery with its attendant risks.
In the past, this option was usually recommended onlyfor higher risk surgical cases because of the possibilitiesof late radiation complications, and the need for ongoingMRI monitoring of the results of the procedure.
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MEDICAL INTERVENTIONS
Stereotactic Radiotherapy
Radiation other than gamma rays can also be used totreat acoustic neuroma.
It is similar to gamma knife
No reason to seek out Stereotactic radiotherapy ratherthan gamma knife. The chance of recurrent tumor usingcurrent dose regimens is roughly 5-10%. Tumor growthis rare in patients who remain stable 6-7 years posttherapy.
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MEDICAL INTERVENTIONS
Surgical Treatment
Translabyrinthine (through the inner ear).
hearing loss is expected and inevitable.
not appropriate for very large tumors.
Retrosigmoid or sub occipital (through the skullbehind the ear).
retraction of the cerebellum (part of the brain) is necessary.
headaches are common after this approach
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MEDICAL INTERVENTIONS
Dr. Hain's approach
suggested that prospective operative candidatesprimarily consider safety and the probability ofcomplications when considering surgery
If one has serviceable hearing prior to surgery, andthere is no other danger of waiting (such as needing abigger operation), one might reasonably simply wait untilhearing becomes unserviceable before proceeding withsurgery or radiation
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OUTCOME INTERVENTIONS
Recovery From Vestibular SchwannomaSurgery: Leaving the Operating Room
Recovery From Vestibular Schwannoma
Surgery: Leaving the ICURecovery From Vestibular Schwannoma
Surgery: Leaving the Hospital
Follow-up Care After Treatment for
Vestibular Schwannoma Vestibular rehabilitation