Acoustic neuroma differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2], Arash Azhideh,

Overview

Acoustic neuroma must be differentiated from meningioma, intracranial epidermoid cyst, facial nerve schwannoma, trigeminal schwannoma, ependymoma, leiomyoma, intranodal palisaded myofibroblastoma, malignant peripheral nerve sheath tumour (MPNST), gastrointestinal stromal tumor, neurofibroma, Meniere's disease, and Bell's palsy.

Differential Diagnosis

Acoustic neuroma must be differentiated from:

• Meningioma
• Intracranial epidermoid cyst
• Facial nerve schwannoma
• Trigeminal schwannoma
• Ependymoma
• Metastasis
• Leiomyoma
• Intranodal palisaded myofibroblastoma
• Gastrointestinal stromal tumor
• MPNST - schwannoma with ancient change has no significant mitotic activity
• Neurofibroma
• Meniere's disease
• Bell's palsy

Differentiating features of common differential diagnoses are:

Differentiating features of common differential diagnosis
Disease/Condition	Differentiating Signs/Symptoms	Findings on CT or MRI
Meningioma	Hearing loss is less common	Usually more homogeneous in appearance: significant signal heterogeneity with cystic or hemorrhagic areas is more typical of vestibular schwannoma than meningiomas (although cystic meningiomas do occur) Meningiomas tend to have a broad dural base Usually lack trumpeted internal acoustic meatus sign Calcification is more common
Intracranial epidermoid cyst	Hearing loss is less common	No enhancing component Very high signal on DWI (Diffusion weighted imaging) Does not widen the internal auditory canal
Facial nerve schwannoma	Facial weakness is common and occurs early Sometimes associated with neurofibromatosis	CT and MRI imaging results are similar to acoustic neuroma but enhancement extends into the geniculate ganglion of the facial nerve and facial canal
Trigeminal schwannoma	Clinically associated with facial numbness Hearing loss is less common	CT and MRI imaging display a dumbbell-shaped mass over the petrous apex affecting Meckel cave. The trigeminal nerve enhancement extends proximal to the tumor and does not extend into the internal acoustic meatus

Differential diagnosis for SSNHL:

Since the most common outcome of acoustic aeuroma is hearing loss, the differential diagnoses for SSNHL (Sudden Sensorineural Hearing Loss ) are listed below.

Identifiable Causes of Sudden Sensorineural Hearing Loss
Autoimmune	Autoimmune inner ear disease	Neurologic	Migraine
	Behcet’s disease		Multiple sclerosis
	Cogan syndrome		Pontine ischemia
	Systemic lupus erythematosis	Otologic	Fluctuating hearing loss
Infectious	Bacterial Meningitis		Meniere’s disease
	Cryptococcal meningitis		Otosclerosis
	HIV AIDS		Enlarged vestibular aqueduct
	Lassa fever	Toxic	Aminoglycosides
	Lyme disease		Chemotherapeutic agents
	Mumps		Non-steroidal anti-inflammatory drugs
	Mycoplasma infection		Salicylates
	Syphilis	Traumatic	Inner ear concussion
	Toxoplasmosis		Iatrogenic trauma/surgery
Vascular	Cardiovascular bypass		Perilymphatic fistula
	Temporal bone fracture		Cerebrovascular accident/stroke
	Sickle cell disease	Metabolic	Diabetes mellitus
Neoplastic	Acoustic neuroma		Hypothyroidism
	Cerebellopontine angle or petrous meningiomas	Functional	Conversion disorder
	Cerebellopontine angle or petrous apex metastases		Malingering
	Cerebellopontine angle myeloma

Differentiating Acoustic Neuroma from Meningioma based on CT Findings

The most important differential diagnosis of acoustic neuroma is meningioma of the pontine angle. Below given diagram demonstrates the difference between acoustic neuroma and meningioma of the pontine angle based on CT scan findings:

<13cm3

Volume

>35cm3

No

Increased attenuation

Yes

No

Marked calcification

Yes

No

Oval shape

Yes

Yes

Round shape

Mostly No

Acoustic Neuroma

No

Tumor reaches dorsum sellae anteriorly

Yes

Meningioma

Mostly No

Apparently broad attachment to bone

Yes

No

Center of tumor anterior to porus

Sometimes Yes

No

Tumor reaches > 2 cm above dorsum

Mostly Yes

Sometimes

Peripheral edema

No

Mostly Yes

Widening of porus or other bone changes

No

Diseases	Clinical manifestations					Para-clinical findings		Gold standard	Additional findings
	Symptoms				Physical examination
						Lab Findings	Imaging
	Acute onset	Recurrency	Nystagmus	Hearing problems
Peripheral
BPPV	+	+	+/−	−	+ Dix-Hallpike maneuver	−	−	Dix-Hallpike maneuver	May be associated with nausea, vomiting, and gait instability
Vestibular neuritis	+	+/−	+ /− (unilateral)	−	+ Head thrust test	−	−	History/ Physical exam	May be associated with nausea, vomiting, gait instability and previous upper respiratory infection
HSV oticus	+	+/−	−	+/−	Taste loss in the front two-thirds of the tongue Acute facial nerve paralysis Vesicles in the ear canal, the tongue, and/or hard palate	+ VZV antibody titres	In MRI with gadolinium dye we may have enhancement of the facial nerve and cranial nerve VIII	History/ Physical exam	May be associated with otalgia, dry mouth, and dry eyes
Meniere disease	+/−	+	+/−	+ (Progressive)	Sensorineural hearing loss	−	In CT scan we may see small or invisible vestibular aqueduct	History/ Physical exam/ Rulling out other diagnoses	May be associated with nausea, vomiting, and tinnitus
Labyrinthine concussion	+	−	−	+	high frequency hearing loss	−	We may see other evidences of head trauma or temporal bone fracture	History/ Physical exam	It happens following blunt head trauma May be associated with dizziness or tinnitus
Perilymphatic fistula	+/−	+	−	+	Tullio phenomenon	−	CT scan may show fluid around the round window recess	History/ Physical exam/Imaging	Can be a complication of a stapedectomy, head injury, or heavy lifting It may be provoked by sneezing, lifting, straining, coughing, and loud sounds
Semicircular canal dehiscence syndrome	+/−	+	−	+ (air-bone gaps on audiometry)	Tullio phenomenon	−	CT scan may show defect in the arcuate eminence of the superior semicircular canal	History/ Physical exam/Imaging	It may be provoked by Valsalva maneuver, coughing, and sneezing
Vestibular paroxysmia	+	+	+/− (Induced by hyperventilation)	−	Impaired caloric testing	−	We may see evidence of vestibulocochlear nerve compression on MRI	History/ Physical exam/Imaging	It may be provoked by head turn or other action They respond well to treatment with carbamazepine or oxcarbazepine
Cogan syndrome	−	+	+/−	+	Interstitial keratitis Oscillopsia Absent vestibular function on caloric test Systemic vasculitis (Aortitis)	Increased ESR and cryoglobulins	In CT scan we may see calcification or soft tissue attenuation obliterating the intralabyrinthine fluid spaces	History/ Physical exam	It may cause Ménière-like attacks
Vestibular schwannoma	−	+	+/−	+	Sensorineural hearing loss + Rinne test Lateralization of Weber test to the normal ear	−	In CT scan we may see erosion, and widening of the internal acoustic meatus Hypointense mass on T1-weighted MRI, and hyperintense mass on T2-weighted MRI	Imaging	Gadolinium-enhanced MRI scan is definitive diagnostic test of acoutic neuroma
Otitis media	+	−	−	+/−	Fever Presence of effusion in the middle ear	Increased acute phase reactants	Opacification of the middle ear	History/ Physical exam	Patient may show other signs and symptoms of upper respiratory infection such az cough, nasal discharge, and fever
Aminoglycoside toxicity	+	−	−	+	Oscillopsia	−	−	History/ Physical exam	May be associated with nausea, vomiting, and ataxia It may be irreversible Gentamicin is the most common one
Recurrent vestibulopathy	+	−	−	−	−	−	−	History/ Physical exam	The underlying pathophysiology is unknown It may happen infrequently, every one to two years It may be associated with nausea and vomiting It may overlap with vestibular migraine
Central
Vestibular migrain	–	+	+/−	+/−	History of migraine headaches	−	They may have white-matter hyperintensities (WMHs) on MRI	ICHD-3 criteria	It may be associated with anxiety and depression
Epileptic vertigo	−	+	+/−	−	They may experience loss of consciousness and motor/sensory problems	−	−	EEG	They response well to anti-seizure drugs
Multiple sclerosis	−	+	+/−	−	Lhermitte's sign Spasticity Increased reflexes Internuclear ophthalmoplegia Optic neuritis Gait disturbance	Elevated concentration of CSF oligoclonal bands	Brain atrophy and some contrast enhancing plaques on CT scan Cerebral plaques disseminating in space and time on MRI	History and physical examination Imaging CSF analysis	MS is at least two times more common among women than men The onset of symptoms is mostly between the age of fifteen to forty years, rarely before age fifteen or after age sixty
Brain tumors	+/−	+	+	+	Papilledema Focal neurological deficits	Cerebral spinal fluid (CSF) may show cancerous cells	On CT scan most of the brain tumors appears as a hypodense mass lesions On MRI most of the brain tumors appears as a hypointense or isointense on T1-weighted scans, or hyperintense on T2-weighted MRI.	Imaging Biopsy	Patieny may experience headache, seizures, visual changes and changes in personality, mood and concentration
Cerebellar infarction/hemorrhage	+	−	++/−	−	Limb ataxia Gait disturbance Dysarthria	−	Based on the time interval between stroke and imaging we may have different presentations	Imaging	Posterior inferior cerebellar artery is the most common artery that causes vertigo
Brain stem ischemia	+	−	+/−	−	Contralateral body weakness Visual field deficits Oculomotor abnormalities Bulbar findings	−	Based on the time interval between stroke and imaging we may have different presentations For more information click here	Imaging	It may be associated with subclavian steal syndrome
Chiari malformation	−	+	+	−	Tachycardia Pupillary dilatation Impaired gag reflex Impaired coordination	−	In CT scan we may see hydrocephalus, herniated cerebellar tonsils, and a flattened spinal cord In MRI we may see cerebellar tonsillar herniation, wedge shaped tonsils, syringohydromyelia, small posterior fossa, obstructive hydrocephalus, and brainstem anomalies	Imaging	Patient may experience ringing in the ears
Parkinson	−	+	−	−	Hypomimia Cogwheel rigidity Resting tremor Gait problems Bradykinesia	−	On brain CT scan, Parkinson disease is characterized by cortical and subcortical atrophy MRI findings in Parkinson disease are reduction in T2 relaxation time and reduced iron content in putamen and GPe	History and physical examination	Patients may present with slowness of movement (bradykinesia), shaking hands while they are at rest (resting tremor) and muscle stiffness (rigidity).

ABBREVIATIONS

VZV= Varicella zoster virus, MRI= Magnetic resonance imaging, ESR= Erythrocyte sedimentation rate, EEG= Electroencephalogram, CSF= Cerebrospinal fluid, GPe= Globus pallidus externa, ICHD= International Classification of Headache Disorders