دهيثم

Lecture ( 3 ) ENT Dr. Haitham Alnori

30 /3/ 2017

Tinnitus

Perception of sounds in the ear or head in the absence of any relevant external stimuli. The classic classification of tinnitus is subjective and objective, however objective tinnitus is rarely encountered (palatal myoclonus and glomus tumor).

Aetiology

Local causes
External and middle ear ( associated with conductive deafness):
Impacted Wax.
Middle ear effusion.
Otosclerosis.
Glomus tumour: pulsatile tinnitus
Inner ear ( associated with SNHL):
Cochlear:
Meniere's disease.
Presbyacusis.
Ototoxic drugs: aminoglycosides and aspirin.
Noise induced hearing loss.
Retrocochlear:
Acoustic neuroma.


General causes
Cardiovascular: HT, heart failure, Hyperdynamic circulation as anemia and hyperthyroidism
Neurological: multiple sclerosis, increased intracranial pressure, Parkinsonism, intracranial tumors
Metabolic: DM, renal failure

Clinical Picture

Tinnitus may has a buzzing, hissing or ringing quality. It may be intermittent or continuous, unilateral or bilateral. Stress and tiredness often make it worse. It is usually more noticeable in bed at night when background noise is at its quietest. In some patients it is very annoying, and may cause depression, even suicide have been reported!

Investigation

Audiology: Audiogram is essential to document any hearing loss.
Radiology: CT scan, MRI if there is suspicion of acoustic neuroma.
MRA and angiography if there is pulsatile tinnitus to exclude glomus jugulare.
Heamatology: CBP, FBS, thyroid function test and lipid profile.

Management

Treatment of tinnitus is not satisfactory. Many groups of drugs have been tried with equivocal results: anti-depressant, anti-epileptic, anti-psychotic, labyrinthine sedative, vasodilators, herbals, …
Treatment of underlying cause and reassurance. Avoid smoking and caffeine beverages.
Drugs: Vestibular vasodilator: Cinnarzin and Betahistin, antidepressants and anxiolytics like alprazolam. Gingko biloba improves brain function by increasing blood flow and oxygenation. Gaba-pentin is helpful.
Tinnitus masker: a small electronic generator that provides noise that is used to mask out a patient tinnitus. Suppression occurs and this continues even after the device is removed. The masker is psychologically much more accepted than tinnitus as it is more tonal in quality and is controllable.
Hearing aids: are helpful to those who have hearing loss sufficient to warrant the issuing of a hearing aid. The awareness of sounds will make tinnitus less apparent.


Vestibular Schwannoma (Acoustic Neuroma)
They are nerve sheath tumors which arise from Schwann cells covering the vestibular nerve (cranial nerve VIII) inside internal auditory canal. Rarely, they originate from the cochlear nerve. Vestibular Schwannomas represent 8% of all intracranial tumors and 80% of cerebello-pontine angle tumors.
They are slowly growing benign encapsulated tumors which do not infiltrate local tissues or metastasize. However, as they grow they compress adjacent tissues.
Acoustic Neuroma is misnomer
They are definitely not neuromas.
They are rarely found on the acoustic nerve.

Aetiology

The cause is unknown. Bilateral vestibular Schwannomas are associated with neurofibromatosis type 2.

Clinical picture ( Tinnitus, Deafness, Vertigo)

The tumor is more common in female with a wide age incidence, usually between 30-60 years. Two phases are recognized: otological phase when the tumor is still intra-canalicular, and neurological phase when the tumor expand medially into cerebello-pontine angle.
Unilateral tinnitus is usually the presenting symptom.
Progressive unilateral SNHL.
Vertigo is not often a prominent feature because the slow growth of the tumor allows central compensation to occur. There is occasional dysequilibrium
Facial and trigeminal nerve dysfunction occur as the tumor starts to expand. The patient may have mid-face numbness, absent corneal reflex and facial palsy.
Hitselberger sign is decreased sensation on the posterior aspect of external auditory canal which is supplied by sensory fibers from facial nerve.
Further expansion leads to brain stem and cerebellar compression and increase intracranial pressure.
Investigation
Audiological: PTA: Shows unilateral SNHL. Speech discrimination is poor because it is retro-cochlear lesion.
Imaging: MRI with gadolinium contrast is the gold standard for the diagnosis.
Caloric test: canal paresis in the affected side.


Differential Diagnosis of cerebello-pontine angle mass:
Acoustic neuroma
Meningioma.
Congenital cholesteatoma.

Treatment

Stereotactic radiation using gamma knife system. It is suitable for small tumors but carry risk of cerebellitis.
Trans-labyrinthine approach: excellent approach to save facial nerve, suitable for those with severe deafness ( because it damages both cochlea and vestibule).
Surgical removal via craniotomy: any tumor size can be dealt with, but have all complications of craniotomy with some risk of facial nerve damage.
Observation only if the life expectancy of the patient is relatively short and the patient has minimal neurological symptoms.

Please remember that

Otosclerosis: Conductive or mixed deafness, tinnitus, rarely vertigo
Menier: Vertigo, fluctuating SNHL, tinnitus
Acoustic neuroma: Unilateral tinnitus, SNHL, vertigo or dysequilibrium