Vestibular Schwannomas

8/2/2019 Vestibular Schwannomas

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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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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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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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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

Vestibular Schwannomas

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