Acoustic Neuroma Symptoms
Acoustic Neuroma
Acoustic neuroma is also known as vestibulas schwannoma.
Acoustic neuroma is a benign proliferation of the Schwann cells that cover the vestibular branch of the eighth cranial nerve (CN VIII). Symptoms are commonly a result of compression of the acoustic branch of CN VIII, the facial nerve (CN VII), and the trigeminal nerve (CN V). The glossopharyngeal nerve (CN IX) and vagus nerve (CN X) are less commonly involved. In extreme cases compression of the brain stem may lead to obstruction of cerebrospinal fluid (CSF) outflow and elevated intracranial pressure (ICP)
The differential diagnosis of acoustic neuroma are Meniere’s disease,trigeminal neuralgiacerebellar disease, normal-pressure hydrocephalus, presbycusis, glomus tumors ,vertebrobasilar insufficiency, ototoxicity from medications,meningioma, glioma and facial nerve schwannoma,cavernous hemangioma and metastatic tumors.
The etiology is incompletely understood, but long-term exposure to acoustic trauma has been implicated. Bilateral acoustic neuromas may be inherited in an autosomal-dominant manner as part of neurofibromatosis type 2. This disease is associated with a defect on chromosome 22q1. Childhood exposure to low-dose radiation for benign head and neck conditions may increase risk for acoustic neuromas. There is inconclusive evidence to link chronic exposure to radiofrequency radiation from cellular telephone use and the risk for developing brain tumors.
Acoustic neuroma is characterized by symptoms and signs. Most frequently unilateral hearing loss and/or tinnitus. Also balance problems, vertigo, facial pain (trigeminal neuralgia) and weakness, difficulty swallowing, fullness or pain of the involved ear. Headache may occur.
With elevated ICP ( intracranial pressure), patients may also have vomiting, fever, and visual changes. Hearing loss is the most common presenting complaint and is usually high frequency.
A detailed neurologic examination with special attention to the cranial nerves is crucial. Otoscopic evaluation may also be required. Audiometry is useful, often showing asymmetric, sensorineural, high-frequency hearing loss. CSF protein may be elevated.
MRI with gadolinium is the preferred test. It can detect tumors as small as 2 mm in diameter. High-resolution CT scan with and without contrast can detect tumors 1 cm in diameter or larger.
Treatment decisions should be based on the size of the tumor, rate of growth (older patients tend to have slower growing tumors), degree of neurologic deficit, desire to preserve hearing, life expectancy, age of the patient, and surgical risk. A combination of
treatments can also be used.
Surgery is the definitive treatment. Choice of approach (middle cranial fossa, translabyrinthine, or retromastoid suboccipital) may vary depending on the size of the tumor, amount of residual hearing desired, and degree of surgical risk that can be tolerated. Partial resection is sometimes undertaken to minimize the risk of injury to nearby structures. Intraoperative facial nerve monitoring is recommended.
Radiation therapy (stereotactic radiotherapy,stereotactic radiosurgery, or proton beam radiotherapy) is useful for tumors ,3 cm in diameter or for those in whom surgery is not an option. Radiotherapy after partial resection has also been used to minimize complications.
Bevacizumab, an antivascular endothelial growth factor (VEGF) monoclonal antibody, has been shown to improve hearing and reduce the volume of growing acoustic neuromas in some neurofibromatosis type 2 patients.
Observation with MRI every 6 to 12 mo may be appropriate for frail patients with small tumors, but risk of unrecoverable hearing loss may increase if surgery is delayed.
Acoustic neuroma is also known as vestibulas schwannoma.
Acoustic neuroma is a benign proliferation of the Schwann cells that cover the vestibular branch of the eighth cranial nerve (CN VIII). Symptoms are commonly a result of compression of the acoustic branch of CN VIII, the facial nerve (CN VII), and the trigeminal nerve (CN V). The glossopharyngeal nerve (CN IX) and vagus nerve (CN X) are less commonly involved. In extreme cases compression of the brain stem may lead to obstruction of cerebrospinal fluid (CSF) outflow and elevated intracranial pressure (ICP)
The differential diagnosis of acoustic neuroma are Meniere’s disease,trigeminal neuralgiacerebellar disease, normal-pressure hydrocephalus, presbycusis, glomus tumors ,vertebrobasilar insufficiency, ototoxicity from medications,meningioma, glioma and facial nerve schwannoma,cavernous hemangioma and metastatic tumors.
The etiology is incompletely understood, but long-term exposure to acoustic trauma has been implicated. Bilateral acoustic neuromas may be inherited in an autosomal-dominant manner as part of neurofibromatosis type 2. This disease is associated with a defect on chromosome 22q1. Childhood exposure to low-dose radiation for benign head and neck conditions may increase risk for acoustic neuromas. There is inconclusive evidence to link chronic exposure to radiofrequency radiation from cellular telephone use and the risk for developing brain tumors.
Acoustic neuroma is characterized by symptoms and signs. Most frequently unilateral hearing loss and/or tinnitus. Also balance problems, vertigo, facial pain (trigeminal neuralgia) and weakness, difficulty swallowing, fullness or pain of the involved ear. Headache may occur.
With elevated ICP ( intracranial pressure), patients may also have vomiting, fever, and visual changes. Hearing loss is the most common presenting complaint and is usually high frequency.
A detailed neurologic examination with special attention to the cranial nerves is crucial. Otoscopic evaluation may also be required. Audiometry is useful, often showing asymmetric, sensorineural, high-frequency hearing loss. CSF protein may be elevated.
MRI with gadolinium is the preferred test. It can detect tumors as small as 2 mm in diameter. High-resolution CT scan with and without contrast can detect tumors 1 cm in diameter or larger.
Treatment decisions should be based on the size of the tumor, rate of growth (older patients tend to have slower growing tumors), degree of neurologic deficit, desire to preserve hearing, life expectancy, age of the patient, and surgical risk. A combination of
treatments can also be used.
Surgery is the definitive treatment. Choice of approach (middle cranial fossa, translabyrinthine, or retromastoid suboccipital) may vary depending on the size of the tumor, amount of residual hearing desired, and degree of surgical risk that can be tolerated. Partial resection is sometimes undertaken to minimize the risk of injury to nearby structures. Intraoperative facial nerve monitoring is recommended.
Radiation therapy (stereotactic radiotherapy,stereotactic radiosurgery, or proton beam radiotherapy) is useful for tumors ,3 cm in diameter or for those in whom surgery is not an option. Radiotherapy after partial resection has also been used to minimize complications.
Bevacizumab, an antivascular endothelial growth factor (VEGF) monoclonal antibody, has been shown to improve hearing and reduce the volume of growing acoustic neuromas in some neurofibromatosis type 2 patients.
Observation with MRI every 6 to 12 mo may be appropriate for frail patients with small tumors, but risk of unrecoverable hearing loss may increase if surgery is delayed.