Vestibular tumor: Difference between revisions
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{{CMG}} ; {{AE}} {{ADG}} | {{CMG}} ; {{AE}} {{ADG}} | ||
==Overview== | ==Overview== | ||
'''Vestibular [[tumor]]s''' are growths that tend to develop | '''Vestibular [[tumor]]s''' are growths that tend to develop in or outside the auditory canal. They may be found anywhere between the chin and the [[larynx]] (or voicebox) and are not more inclined to one side of the body than the other. They are predominantly present in adolescent females though they are not directly related to any hygienal issues. While [[surgery]] is the most often cure, deaths rarely occur due to the existence of vestibular tumors. | ||
==Historical Perspective== | ==Historical Perspective== | ||
The first reported case of a vestibular tumor was in 1898 in | The first reported case of a vestibular tumor was in 1898 in Lancaster, Pennsylvania. Though there have been stories of growths of the like of vestibular tumors, this was the first medically reported case. At the time, surgery was too dangerous, so Emilia Walfen was forced to live with the tumor, which eventually grew to the size of a [[Concord grape]]. | ||
== Pathogenesis == | == Pathogenesis == | ||
Recent studies in NF2 patients led to the identification of the neurofibromin 2 gene, which is located on chromosome 22. The ''NF2'' gene produces merlin, also known as schwannomin, a cell membrane-related protein that acts as a tumor suppressor. | Recent studies in [[NF2 gene|NF2]] patients led to the identification of the [[NF2 gene|neurofibromin 2 gene]], which is located on [[chromosome 22]]. The [[NF2 gene|''NF2'' gene]] produces [[Merlin (protein)|merlin]], also known as schwannomin, a cell membrane-related protein that acts as a tumor suppressor. Bi-[[Allele|allelic]] inactivation of the [[NF2 gene|''NF2'' gene]] is found in most sporadic vestibular schwannomas. | ||
=== Microscopic pathology === | === Microscopic pathology === | ||
* Vestibular schwannomas arise from perineural elements of the Schwann cell. | * Vestibular schwannomas arise from perineural elements of the [[Schwann cell]]. | ||
* They occur with equal frequency on the superior and inferior branches of the vestibular nerve. | * They occur with equal frequency on the superior and inferior branches of the [[vestibular nerve]]. | ||
* Microscopically, zones of alternately dense and sparse cellularity, called Antoni A and B areas, respectively, are characteristic of vestibular schwannomas. | * Microscopically, zones of alternately dense and sparse [[Cell (biology)|cellularity]], called Antoni A and B areas, respectively, are characteristic of vestibular schwannomas. | ||
* Malignant degeneration is extremely rare, with only six cases having been reported. | * Malignant degeneration is extremely rare, with only six cases having been reported. | ||
* Immunohistochemical staining for S100 protein is usually positive in both the benign and the rare malignant forms of this tumor. | *[[Immunohistochemistry|Immunohistochemical]] staining for S100 protein is usually positive in both the benign and the rare malignant forms of this [[tumor]]. | ||
== Differentiating Vestibular schwannoma from other diseases == | == Differentiating Vestibular schwannoma from other diseases == | ||
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! colspan="11" style="background: #7d7d7d; color: #FFFFFF; padding: 5px; text-align: center;" |Adult primary brain tumors | ! colspan="11" style="background: #7d7d7d; color: #FFFFFF; padding: 5px; text-align: center;" |Adult primary brain tumors | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Meningioma]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Meningioma]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* May be associated with [[Neurofibromatosis type II|NF-2]] | * May be associated with [[Neurofibromatosis type II|NF-2]] | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Glioblastoma multiforme]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Glioblastoma multiforme]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* Most of the time, focal [[neurological]] deficit is the presenting [[Sign (medical)|sign]]. | * Most of the time, focal [[neurological]] deficit is the presenting [[Sign (medical)|sign]]. | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Oligodendroglioma]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Oligodendroglioma]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
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* Most of the time, [[epileptic seizure]] is the presenting [[Sign (medicine)|sign]]. | * Most of the time, [[epileptic seizure]] is the presenting [[Sign (medicine)|sign]]. | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Hemangioblastoma]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Hemangioblastoma]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* May be associated with [[Von Hippel-Lindau Disease|von hippel-lindau syndrome]] | * May be associated with [[Von Hippel-Lindau Disease|von hippel-lindau syndrome]] | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Pituitary adenoma]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Pituitary adenoma]]<br><ref name=":0" /> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | − | | style="background: #F5F5F5; padding: 5px; text-align: center;" | − | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | − | | style="background: #F5F5F5; padding: 5px; text-align: center;" | − | ||
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* | * | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Schwannoma]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Schwannoma]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | − | | style="background: #F5F5F5; padding: 5px; text-align: center;" | − | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | − | | style="background: #F5F5F5; padding: 5px; text-align: center;" | − | ||
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* May be associated with [[Neurofibromatosis type II|NF-2]] (bilateral [[Schwannoma|schwannomas]]) | * May be associated with [[Neurofibromatosis type II|NF-2]] (bilateral [[Schwannoma|schwannomas]]) | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Primary central nervous system lymphoma|Primary CNS lymphoma]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Primary central nervous system lymphoma|Primary CNS lymphoma]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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! colspan="11" style="background: #7d7d7d; color: #FFFFFF; padding: 5px; text-align: center;" |Childhood primary brain tumors | ! colspan="11" style="background: #7d7d7d; color: #FFFFFF; padding: 5px; text-align: center;" |Childhood primary brain tumors | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Pilocytic astrocytoma]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Pilocytic astrocytoma]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* Most of the time, [[Cerebellum|cerebellar]] dysfunction is the presenting [[signs]]. | * Most of the time, [[Cerebellum|cerebellar]] dysfunction is the presenting [[signs]]. | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Medulloblastoma]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Medulloblastoma]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* [[Drop metastasis]] ([[metastasis]] through [[CSF]]) | * [[Drop metastasis]] ([[metastasis]] through [[CSF]]) | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Ependymoma]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Ependymoma]]<br><ref name=":0" /> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* Causes an unusually persistent, continuous [[headache]] in children. | * Causes an unusually persistent, continuous [[headache]] in children. | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Craniopharyngioma]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Craniopharyngioma]]<br><ref name=":0" /> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* Initialy presents with lower bitemporal quadrantanopsia followed by [[Bitemporal hemianopia|bitemporal hemianopsia]] (pressure on [[Optic chiasm|optic chiasma]] from above) | * Initialy presents with lower bitemporal quadrantanopsia followed by [[Bitemporal hemianopia|bitemporal hemianopsia]] (pressure on [[Optic chiasm|optic chiasma]] from above) | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Pinealoma]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Pinealoma]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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! colspan="11" style="background: #7d7d7d; color: #FFFFFF; padding: 5px; text-align: center;" |Vascular | ! colspan="11" style="background: #7d7d7d; color: #FFFFFF; padding: 5px; text-align: center;" |Vascular | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Arteriovenous malformation|AV malformation]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Arteriovenous malformation|AV malformation]]<br><ref name=":0" /> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
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* We may see bag of worms appearance in [[CT angiography]] | * We may see bag of worms appearance in [[CT angiography]] | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Brain aneurysm]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Brain aneurysm]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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! colspan="11" style="background: #7d7d7d; color: #FFFFFF; padding: 5px; text-align: center;" |Infectious | ! colspan="11" style="background: #7d7d7d; color: #FFFFFF; padding: 5px; text-align: center;" |Infectious | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |Bacterial [[brain abscess]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |Bacterial [[brain abscess]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* The most common causes of [[brain abscess]] are [[Streptococcus]] and [[Staphylococcus]]. | * The most common causes of [[brain abscess]] are [[Streptococcus]] and [[Staphylococcus]]. | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Tuberculosis]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Tuberculosis]]<br><ref name=":0" /> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* It is associated with [[HIV]] [[infection]] | * It is associated with [[HIV]] [[infection]] | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Toxoplasmosis]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Toxoplasmosis]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* It is associated with [[HIV]] [[infection]] | * It is associated with [[HIV]] [[infection]] | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Hydatid cyst]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Hydatid cyst]]<br><ref name=":0" /> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* [[Brain]], [[eye]], and [[Spleen|splenic]] [[Cyst|cysts]] may not produce detectable amount of [[antibodies]] | * [[Brain]], [[eye]], and [[Spleen|splenic]] [[Cyst|cysts]] may not produce detectable amount of [[antibodies]] | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[CNS]] [[cryptococcosis]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[CNS]] [[cryptococcosis]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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* Since [[brain]] [[Biopsy|biopsies]] are highly invasive and may may cause [[neurological]] deficits, we [[diagnose]] [[CNS]] [[fungal]] [[Infection|infections]] based on [[laboratory]] and imaging findings | * Since [[brain]] [[Biopsy|biopsies]] are highly invasive and may may cause [[neurological]] deficits, we [[diagnose]] [[CNS]] [[fungal]] [[Infection|infections]] based on [[laboratory]] and imaging findings | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[CNS]] [[aspergillosis]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[CNS]] [[aspergillosis]]<br> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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! colspan="11" style="background: #7d7d7d; color: #FFFFFF; padding: 5px; text-align: center;" |Other | ! colspan="11" style="background: #7d7d7d; color: #FFFFFF; padding: 5px; text-align: center;" |Other | ||
|- | |- | ||
| style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Brain metastasis]]<br | | style="background: #DCDCDC; padding: 5px; text-align: center;" |[[Brain metastasis]]<br><ref name=":0" /> | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | + | | style="background: #F5F5F5; padding: 5px; text-align: center;" | + | ||
| style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | | style="background: #F5F5F5; padding: 5px; text-align: center;" | +/− | ||
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== Risk Factors == | == Risk Factors == | ||
Common risk factors for the development of vestibular schwaomas include: | Common [[risk factors]] for the development of vestibular schwaomas include: | ||
* Childhood exposure to low-dose radiation for benign conditions of the head and neck | * Childhood exposure to low-dose [[radiation]] for benign conditions of the head and neck | ||
* Radiofrequency | *[[Radiofrequency]] exposure from the use of mobile phones | ||
* | * Excessive noise exposure | ||
== Epidemiology and Demographics == | == Epidemiology and Demographics == | ||
=== Incidence === | === Incidence === | ||
* The overall incidence of vestibular schwannomas is approximately 1 per 100,000 person-years in the United States. | * The overall [[incidence]] of vestibular schwannomas is approximately 1 per 100,000 person-years in the United States. | ||
* Bilateral vestibular schwannomas are primarily observed in patients with neurofibromatosis type 2 (NF2). | *[[Bilateral]] vestibular schwannomas are primarily observed in patients with [[neurofibromatosis type 2]] ([[Neurofibromatosis type II|NF2]]). | ||
* The tumors are unilateral in more than 90 percent of cases, affecting the right and left sides with equal frequency. | * The [[tumors]] are unilateral in more than 90 percent of cases, affecting the right and left sides with equal frequency. | ||
=== Age === | === Age === | ||
* The median age at diagnosis is approximately 50 years. | * The [[median]] age at diagnosis is approximately 50 years. | ||
=== Gender === | === Gender === | ||
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==Natural History, Complications, and Prognosis== | ==Natural History, Complications, and Prognosis== | ||
Vestibular schwanama pose a major health impediment if left untreated as they might cause pressure on adjacent posterior fossa structures such as cerebellum or brainstem and result in ataxia | Vestibular schwanama pose a major health impediment if left untreated as they might cause pressure on adjacent [[posterior fossa]] structures such as [[cerebellum]] or [[brainstem]] and result in [[ataxia]], [[brainstem]] compression, [[Cerebellar tonsill herniation|cerebellar tonsil herniation]], [[hydrocephalus]], and death can occur in untreated cases. Common [[Complication (medicine)|complication]] include [[seizures]] and paralysis [[difficulty swallowing]] due to the pressure on the [[tongue]] or [[pharynx]]. The functions of the lower [[cranial nerves]] can also become impaired, leading to [[dysarthria]], [[dysphagia]], [[aspiration]], and [[hoarseness]]. | ||
== Diagnosis == | == Diagnosis == | ||
=== History and Symptoms === | === History and Symptoms === | ||
* Symptoms associated with vestibular schwannoma can be due to cranial nerve involvement, cerebellar compression, or tumor progression. Clinical manifestations in this series included the following: | *[[Symptoms]] associated with vestibular schwannoma can be due to [[Cranial nerves|cranial nerve]] involvement, [[Cerebellum|cerebellar]] compression, or [[tumor]] progression. Clinical manifestations in this series included the following: | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
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!Symtpoms | !Symtpoms | ||
|- | |- | ||
|Cochlear nerve | |[[Cochlear nerve]] | ||
|95 percent | |95 percent | ||
| | | | ||
* Hearing loss | *[[Hearing loss]] | ||
* Tinnitus | *[[Tinnitus]] | ||
|- | |- | ||
|Vestibular nerve | |[[Vestibular nerve]] | ||
|61 percent | |61 percent | ||
| | | | ||
Line 572: | Line 572: | ||
* Brief tilting or veering | * Brief tilting or veering | ||
|- | |- | ||
|Trigeminal nerve | |[[Trigeminal nerve]] | ||
|17 percent | |17 percent | ||
| | | | ||
* Facial numbness (paresthesia), hypesthesia, and pain. | * Facial numbness ([[paresthesia]]), [[hypesthesia]], and [[pain]]. | ||
|- | |- | ||
|Facial nerve | |[[Facial nerve]] | ||
|6 percent | |6 percent | ||
| | | | ||
* Facial paresis | *[[Facial paralysis|Facial paresis]] | ||
* Taste disturbances (due to nervus intermedius impairment). | * Taste disturbances (due to [[nervus intermedius]] impairment). | ||
* Xerophthalmia | *[[Xerophthalmia]] | ||
* Paroxysmal lacrimation | * Paroxysmal [[lacrimation]] | ||
* Xerostomia | *[[Xerostomia]] | ||
|- | |- | ||
|Tumor progression | |[[Tumor]] progression | ||
| | | | ||
| | | | ||
* Pressure on adjacent posterior fossa structures such as cerebellum or brainstem and result in ataxia | * Pressure on adjacent [[posterior fossa]] structures such as [[cerebellum]] or [[brainstem]] and result in [[ataxia]] | ||
* Brainstem compression, cerebellar tonsil herniation, hydrocephalus, and death can occur in untreated cases | *[[Brainstem]] compression, [[Cerebellar tonsill herniation|cerebellar tonsil herniation]], [[hydrocephalus]], and death can occur in untreated cases | ||
|} | |} | ||
=== Physical Examination === | === Physical Examination === | ||
* Hearing tests are typically abnormal due to involvement of the acoustic nerve. | * Hearing tests are typically abnormal due to involvement of the [[acoustic nerve]]. | ||
** The Weber and Rinne tests may be useful in suggesting asymmetric sensorineural hearing impairment. | ** The [[Weber test|Weber]] and [[Rinne test|Rinne tests]] may be useful in suggesting asymmetric [[sensorineural hearing impairment]]. | ||
* Neurologic examination may reveal other cranial nerve deficits | *[[Neurological|Neurologic]] examination may reveal other [[Cranial nerve disease|cranial nerve deficits]] | ||
** A decreased or absent ipsilateral corneal reflex and facial twitching or hypesthesia may occur as cranial nerves V and VII become affected. | ** A decreased or absent [[ipsilateral]] [[corneal reflex]] and facial [[twitching]] or [[hypesthesia]] may occur as [[Trigeminal nerve|cranial nerves V]] and [[Facial nerve|VII]] become affected. | ||
** Romberg, Hall-Pike, and other common office balance tests are typically normal. | **[[Romberg's test|Romberg]], Hall-Pike, and other common office balance tests are typically normal. | ||
=== CT === | === CT === | ||
Findings of vestibular schwanoma on CT include: | Findings of vestibular schwanoma on [[CT-scans|CT]] include: | ||
* Erosion and widening of the internal acoustic canal. | * Erosion and widening of the internal acoustic canal. | ||
* The density of these tumors on non-contrast imaging is variable, and often they are hard to see, especially on account of beam hardening and streak artefact from the adjacent petrous temporal bone. | * The density of these [[tumors]] on non-contrast imaging is variable, and often they are hard to see, especially on account of beam hardening and streak artefact from the adjacent [[petrous temporal bone]]. | ||
* Contrast enhancement is present but can be underwhelming, especially in larger lesions with cystic components. | *[[Contrast enhanced CT|Contrast enhancement]] is present but can be underwhelming, especially in larger lesions with cystic components. | ||
=== MRI === | === MRI === | ||
MRI findings of vestibular schwanoma include: | [[MRI]] findings of vestibular schwanoma include: | ||
{| class="wikitable" | {| class="wikitable" | ||
Line 617: | Line 617: | ||
|'''T1''' | |'''T1''' | ||
| | | | ||
* Slightly hypointense to the adjacent brain. | * Slightly hypointense to the adjacent [[brain]]. | ||
* Isointense to the adjacent brain | * Isointense to the adjacent [[brain]] | ||
* May contain hypointense cystic areas | * May contain hypointense cystic areas | ||
|- | |- | ||
|'''T2''' | |'''T2''' | ||
| | | | ||
** Heterogeneously hyperintense to adjacent brain | ** Heterogeneously hyperintense to adjacent [[brain]] | ||
** Fluid intensity cystic areas | ** Fluid intensity cystic areas | ||
** May have associated peritumoral arachnoid cysts | ** May have associated peritumoral [[arachnoid cysts]] | ||
* | * | ||
|- | |- | ||
|'''T1 C+ (Gd)''' | |'''T1 C+ (Gd)''' | ||
|Contrast enhancement is intense however, heterogeneous in larger tumors | |[[Contrast enhanced CT|Contrast enhancement]] is intense however, heterogeneous in larger [[tumors]] | ||
|} | |} | ||
=== Other Diagnostic Studies === | === Other Diagnostic Studies === | ||
'''Audiometry''' | '''Audiometry''' | ||
* Audiometry is the best initial screening laboratory test for the diagnosis of vestibular schwannoma. | *[[Audiometry]] is the best initial screening laboratory test for the [[diagnosis]] of vestibular schwannoma. | ||
* Pure tone and speech audiometry should be performed in an acoustically shielded area. | * Pure tone and speech [[audiometry]] should be performed in an acoustically shielded area. | ||
* Test results typically show an asymmetric sensorineural hearing loss, usually more prominent in the higher frequencies. | * Test results typically show an asymmetric [[sensorineural hearing loss]], usually more prominent in the higher frequencies. | ||
* Hearing loss does not necessarily correlate with tumor size. | * Hearing loss does not necessarily correlate with [[tumor]] size. | ||
* The speech discrimination score is usually markedly reduced in the affected ear and out of proportion to the measured hearing loss. | * The speech discrimination score is usually markedly reduced in the affected ear and out of proportion to the measured [[hearing loss]]. | ||
* Common audiometry tests that are of current practice include: | * Common audiometry tests that are of current practice include: | ||
** Acoustic reflex testing | **[[Acoustic reflex]] testing | ||
** Impedance audiometry | ** Impedance [[audiometry]] | ||
** Bekesy audiometry | ** Bekesy [[audiometry]] | ||
** Brainstem-evoked response audiometry (AER/ABR). | ** Brainstem-evoked response [[audiometry]] (AER/ABR). | ||
'''Vestibular testing''' | '''Vestibular testing''' | ||
* Vestibular testing has limited utility as a screening test for the diagnosis of vestibular schwannoma because of the accuracy of evoked response audiometry. | *[[Vestibular system|Vestibular]] testing has limited utility as a screening test for the diagnosis of vestibular schwannoma because of the accuracy of evoked response [[audiometry]]. | ||
* When testing is performed, a decreased or absent caloric response on the affected side may be seen. When the tumor is small, though, a normal response is often seen. | * When testing is performed, a decreased or absent caloric response on the affected side may be seen. When the [[tumor]] is small, though, a normal response is often seen. | ||
** | ** | ||
Line 652: | Line 652: | ||
==Treatment== | ==Treatment== | ||
Treatment options for patients with a vestibular schwannoma include surgery and radiation therapy. | Treatment options for patients with a vestibular schwannoma include [[surgery]] and [[radiation therapy]]. | ||
=== Surgery === | === Surgery === | ||
Surgery generally results in satisfactory long-term control of vestibular schwannomas. There are three standard operative approaches. | [[Surgery]] generally results in satisfactory long-term control of vestibular schwannomas. There are three standard operative approaches. | ||
{| class="wikitable" | {| class="wikitable" | ||
Line 662: | Line 662: | ||
|- | |- | ||
|Retromastoid suboccipital (retrosigmoid) | |Retromastoid suboccipital (retrosigmoid) | ||
|The suboccipital approach can be used for any size tumor with or without attempted hearing preservation. | |The suboccipital approach can be used for any size [[tumor]] with or without attempted [[hearing]] preservation. | ||
|- | |- | ||
|Translabyrinthine | |Translabyrinthine | ||
|The translabyrinthine approach has been recommended for acoustic tumors larger than 3 cm and for smaller tumors when hearing preservation is not an issue. | |The translabyrinthine approach has been recommended for acoustic [[tumors]] larger than 3 cm and for smaller [[tumors]] when hearing preservation is not an issue. | ||
|- | |- | ||
|Middle fossa | |Middle fossa | ||
|The middle fossa approach is suitable for small (<1.5 cm) tumors when hearing preservation is a goal. | |The middle fossa approach is suitable for small (<1.5 cm) [[tumors]] when hearing preservation is a goal. | ||
|} | |} | ||
=== Radiation therapy === | === Radiation therapy === | ||
Radiation therapy for patients with vestibular schwannoma include stereotactic radiosurgery (SRS), stereotactic radiotherapy (SRT), and proton beam therapy, as well as conventional fractionated radiation therapy. | [[Radiation therapy]] for patients with vestibular schwannoma include [[stereotactic radiosurgery]] (SRS), stereotactic radiotherapy (SRT), and proton beam therapy, as well as conventional fractionated [[radiation therapy]]. | ||
{| class="wikitable" | {| class="wikitable" | ||
Line 680: | Line 680: | ||
|'''Stereotactic radiosurgery''' | |'''Stereotactic radiosurgery''' | ||
| | | | ||
* SRS is a technique that utilizes multiple convergent beams to deliver a high single dose of radiation to a radiographically discrete treatment volume, thereby minimizing injury to adjacent structures. | * SRS is a technique that utilizes multiple convergent beams to deliver a high single dose of [[radiation]] to a radiographically discrete treatment volume, thereby minimizing injury to adjacent structures. | ||
* This can be accomplished with either the gamma knife or a linear accelerator. | * This can be accomplished with either the [[Gamma Knife|gamma knife]] or a linear accelerator. | ||
* Radiosurgery is a viable treatment option for selected patients with smaller tumors (<3 cm) or for enlarging tumors in patients who are not candidates for surgery | * Radiosurgery is a viable treatment option for selected patients with smaller [[tumors]] (<3 cm) or for enlarging [[tumors]] in patients who are not candidates for [[surgery]] | ||
|- | |- | ||
|'''Stereotactic radiotherapy''' | |'''Stereotactic radiotherapy''' | ||
| | | | ||
* Fractionated SRT utilizes focused doses of radiation given over a series of treatment sessions. | * Fractionated SRT utilizes focused doses of radiation given over a series of treatment sessions. | ||
* The intent is to reduce radiation injury to critical neural structures while preserving tumor control. | * The intent is to reduce [[radiation]] injury to critical neural structures while preserving [[tumor]] control. | ||
|- | |- | ||
|'''Proton beam therapy''' | |'''Proton beam therapy''' | ||
| | | | ||
* Proton beam therapy may provide maximal local tumor control while minimizing cranial nerve injuries. | * Proton beam therapy may provide maximal local [[tumor]] control while minimizing [[Cranial nerves|cranial nerve]] injuries. | ||
* The physical characteristics of the beam result in the majority of the energy being deposited at the end of a linear track (the Bragg peak), with the dose falling rapidly to zero beyond the Bragg peak. | * The physical characteristics of the beam result in the majority of the energy being deposited at the end of a linear track (the Bragg peak), with the dose falling rapidly to zero beyond the Bragg peak. | ||
* Thus, the use of proton beam therapy permits the delivery of high doses of radiation therapy to the target volume while limiting the "scatter" dose received by surrounding tissues. | * Thus, the use of proton beam therapy permits the delivery of high doses of [[radiation therapy]] to the target volume while limiting the "scatter" dose received by surrounding [[Tissue (biology)|tissues]]. | ||
|} | |} | ||
Line 703: | Line 703: | ||
[[Category:Medicine]] | [[Category:Medicine]] | ||
[[Category:Otolaryngology]] | [[Category:Otolaryngology]] | ||
<references /> |
Latest revision as of 20:37, 22 October 2019
Template:Vestibular tumor Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]
Overview
Vestibular tumors are growths that tend to develop in or outside the auditory canal. They may be found anywhere between the chin and the larynx (or voicebox) and are not more inclined to one side of the body than the other. They are predominantly present in adolescent females though they are not directly related to any hygienal issues. While surgery is the most often cure, deaths rarely occur due to the existence of vestibular tumors.
Historical Perspective
The first reported case of a vestibular tumor was in 1898 in Lancaster, Pennsylvania. Though there have been stories of growths of the like of vestibular tumors, this was the first medically reported case. At the time, surgery was too dangerous, so Emilia Walfen was forced to live with the tumor, which eventually grew to the size of a Concord grape.
Pathogenesis
Recent studies in NF2 patients led to the identification of the neurofibromin 2 gene, which is located on chromosome 22. The NF2 gene produces merlin, also known as schwannomin, a cell membrane-related protein that acts as a tumor suppressor. Bi-allelic inactivation of the NF2 gene is found in most sporadic vestibular schwannomas.
Microscopic pathology
- Vestibular schwannomas arise from perineural elements of the Schwann cell.
- They occur with equal frequency on the superior and inferior branches of the vestibular nerve.
- Microscopically, zones of alternately dense and sparse cellularity, called Antoni A and B areas, respectively, are characteristic of vestibular schwannomas.
- Malignant degeneration is extremely rare, with only six cases having been reported.
- Immunohistochemical staining for S100 protein is usually positive in both the benign and the rare malignant forms of this tumor.
Differentiating Vestibular schwannoma from other diseases
The differential diagnosis includes meningioma, facial nerve schwannomas, gliomas, cholesterol cysts, cholesteatomas, hemangiomas, aneurysms, arachnoid cysts, lipomas, and metastatic tumor. For more information click here On the basis of seizure, visual disturbance, and constitutional symptoms, meningioma must be differentiated from oligodendroglioma, astrocytoma, hemangioblastoma, pituitary adenoma, schwannoma, primary CNS lymphoma, medulloblastoma, ependymoma, craniopharyngioma, pinealoma, AV malformation, brain aneurysm, bacterial brain abscess, tuberculosis, toxoplasmosis, hydatid cyst, CNS cryptococcosis, CNS aspergillosis, and brain metastasis.
Diseases | Clinical manifestations | Para-clinical findings | Gold standard |
Additional findings | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Symptoms | Physical examination | |||||||||
Lab Findings | MRI | Immunohistopathology | ||||||||
Head- ache |
Seizure | Visual disturbance | Constitutional | Focal neurological deficit | ||||||
Adult primary brain tumors | ||||||||||
Meningioma |
+ | +/− | +/− | − | + | − |
|
|
| |
Glioblastoma multiforme |
+ | +/− | +/− | − | + | − |
|
|
| |
Oligodendroglioma |
+ | + | +/− | − | + | − |
|
|
| |
Hemangioblastoma |
+ | +/− | +/− | − | + | − |
|
| ||
Pituitary adenoma [1] |
− | − | + Bitemporal hemianopia | − | − |
|
|
|
| |
Schwannoma |
− | − | − | − | + | − |
|
|
| |
Primary CNS lymphoma |
+ | +/− | +/− | − | + | − |
|
|
| |
Childhood primary brain tumors | ||||||||||
Pilocytic astrocytoma |
+ | +/− | +/− | − | + | − |
|
|
| |
Medulloblastoma |
+ | +/− | +/− | − | + | − |
|
|
| |
Ependymoma [1] |
+ | +/− | +/− | − | + | − |
|
|
| |
Craniopharyngioma [1] |
+ | +/− | + Bitemporal hemianopia | − | + |
|
|
|
| |
Pinealoma |
+ | +/− | +/− | − | + vertical gaze palsy |
|
|
|
| |
Vascular | ||||||||||
AV malformation [1] |
+ | + | +/− | − | +/− | − |
|
| ||
Brain aneurysm |
+ | +/− | +/− | − | +/− | − |
|
|
|
|
Infectious | ||||||||||
Bacterial brain abscess |
+ | +/− | +/− | + | + |
|
|
|
|
|
Tuberculosis [1] |
+ | +/− | +/− | + | + |
|
|
|
|
|
Toxoplasmosis |
+ | +/− | +/− | − | + |
|
|
|
|
|
Hydatid cyst [1] |
+ | +/− | +/− | +/− | + |
|
|
|
|
|
CNS cryptococcosis |
+ | +/− | +/− | + | + |
|
|
|
|
|
CNS aspergillosis |
+ | +/− | +/− | + | + |
|
|
|
|
|
Other | ||||||||||
Brain metastasis [1] |
+ | +/− | +/− | + | + | − |
|
|
|
|
ABBREVIATIONS
CNS=Central nervous system, AV=Arteriovenous, CSF=Cerebrospinal fluid, NF-2=Neurofibromatosis type 2, MEN-1=Multiple endocrine neoplasia, GFAP=Glial fibrillary acidic protein, HIV=Human immunodeficiency virus, BhCG=Human chorionic gonadotropin, ESR=Erythrocyte sedimentation rate, AFB=Acid fast bacilli, MRA=Magnetic resonance angiography, CTA=CT angiography
Risk Factors
Common risk factors for the development of vestibular schwaomas include:
- Childhood exposure to low-dose radiation for benign conditions of the head and neck
- Radiofrequency exposure from the use of mobile phones
- Excessive noise exposure
Epidemiology and Demographics
Incidence
- The overall incidence of vestibular schwannomas is approximately 1 per 100,000 person-years in the United States.
- Bilateral vestibular schwannomas are primarily observed in patients with neurofibromatosis type 2 (NF2).
- The tumors are unilateral in more than 90 percent of cases, affecting the right and left sides with equal frequency.
Age
- The median age at diagnosis is approximately 50 years.
Gender
- Vestibular schwannomas occur equally in both genders.
Natural History, Complications, and Prognosis
Vestibular schwanama pose a major health impediment if left untreated as they might cause pressure on adjacent posterior fossa structures such as cerebellum or brainstem and result in ataxia, brainstem compression, cerebellar tonsil herniation, hydrocephalus, and death can occur in untreated cases. Common complication include seizures and paralysis difficulty swallowing due to the pressure on the tongue or pharynx. The functions of the lower cranial nerves can also become impaired, leading to dysarthria, dysphagia, aspiration, and hoarseness.
Diagnosis
History and Symptoms
- Symptoms associated with vestibular schwannoma can be due to cranial nerve involvement, cerebellar compression, or tumor progression. Clinical manifestations in this series included the following:
Never involvement | Incidence | Symtpoms |
---|---|---|
Cochlear nerve | 95 percent | |
Vestibular nerve | 61 percent |
|
Trigeminal nerve | 17 percent |
|
Facial nerve | 6 percent |
|
Tumor progression |
|
Physical Examination
- Hearing tests are typically abnormal due to involvement of the acoustic nerve.
- The Weber and Rinne tests may be useful in suggesting asymmetric sensorineural hearing impairment.
- Neurologic examination may reveal other cranial nerve deficits
- A decreased or absent ipsilateral corneal reflex and facial twitching or hypesthesia may occur as cranial nerves V and VII become affected.
- Romberg, Hall-Pike, and other common office balance tests are typically normal.
CT
Findings of vestibular schwanoma on CT include:
- Erosion and widening of the internal acoustic canal.
- The density of these tumors on non-contrast imaging is variable, and often they are hard to see, especially on account of beam hardening and streak artefact from the adjacent petrous temporal bone.
- Contrast enhancement is present but can be underwhelming, especially in larger lesions with cystic components.
MRI
MRI findings of vestibular schwanoma include:
MRI findings of Vestibular Schwanoma | |
---|---|
T1 | |
T2 |
|
T1 C+ (Gd) | Contrast enhancement is intense however, heterogeneous in larger tumors |
Other Diagnostic Studies
Audiometry
- Audiometry is the best initial screening laboratory test for the diagnosis of vestibular schwannoma.
- Pure tone and speech audiometry should be performed in an acoustically shielded area.
- Test results typically show an asymmetric sensorineural hearing loss, usually more prominent in the higher frequencies.
- Hearing loss does not necessarily correlate with tumor size.
- The speech discrimination score is usually markedly reduced in the affected ear and out of proportion to the measured hearing loss.
- Common audiometry tests that are of current practice include:
- Acoustic reflex testing
- Impedance audiometry
- Bekesy audiometry
- Brainstem-evoked response audiometry (AER/ABR).
Vestibular testing
- Vestibular testing has limited utility as a screening test for the diagnosis of vestibular schwannoma because of the accuracy of evoked response audiometry.
- When testing is performed, a decreased or absent caloric response on the affected side may be seen. When the tumor is small, though, a normal response is often seen.
Treatment
Treatment options for patients with a vestibular schwannoma include surgery and radiation therapy.
Surgery
Surgery generally results in satisfactory long-term control of vestibular schwannomas. There are three standard operative approaches.
Surgery | |
---|---|
Retromastoid suboccipital (retrosigmoid) | The suboccipital approach can be used for any size tumor with or without attempted hearing preservation. |
Translabyrinthine | The translabyrinthine approach has been recommended for acoustic tumors larger than 3 cm and for smaller tumors when hearing preservation is not an issue. |
Middle fossa | The middle fossa approach is suitable for small (<1.5 cm) tumors when hearing preservation is a goal. |
Radiation therapy
Radiation therapy for patients with vestibular schwannoma include stereotactic radiosurgery (SRS), stereotactic radiotherapy (SRT), and proton beam therapy, as well as conventional fractionated radiation therapy.
Radiation therapy | |
---|---|
Stereotactic radiosurgery |
|
Stereotactic radiotherapy | |
Proton beam therapy |
|