Tinnitus Grand Rounds Edward Buckingham, M. D



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Tinnitus Grand Rounds

  • Edward Buckingham, M. D.

  • Jeff Vrabec, M. D., Faculty Sponcer

  • Francis Quinn, M.D., Series Editor


Introduction

  • Def. - Perception of sound produced involuntarily within the body

  • Sypmtom of threatening disease process or benign annoyance

  • Psychological effects can be severe, even precipitate suicide



Definition and Epidemiology

  • Objective, paraauditory tinnitus - vascular or myoclonic sources, less prevalent

  • Subjective, sensorineural tinnitus - auditory system, more prevalent

  • Prevalence increases with age

  • Equal sex distribution

  • Severity of symptoms increases with age



Objective Tinnitus

  • Stictly def. audible to physician or observer

  • Encompasses all paraauditory causes

  • Pulsatile or non-pulsatile

  • Vascular abnormalities - neoplasm, AVM, arterial bruit, venous hums

  • Palatomyoclonus



Objective Tinnitus - 2

  • H & P

  • Relation to the heart rate, light exercise

  • Thorough ENT exam, particulary otoscopy

  • Exam for retrotympanic mass

  • Auscultate ext. canal, orbit, mastoid, skull, and neck

  • Audiogram



Pulsatile Tinnitus

  • Many causes

  • Possible algorithm from Sismanis

  • H & P most important

  • BIH, ACAD, Glomus tumors 2/3 of causes



Benign Intracranial Hypertension (pseudotumor cerebri) Syndrome

  • Most common cause in Sismanis’s study

  • Increased ICP, no focal neuro defecit except occas. 6th or 7th nerve palsy

  • Mech. systolic pulsation of CSF to medial aspect of dural venous sinuses, compression of walls, turbulent blood flow

  • Head imaging, r/o IC lesion

  • Diagnose by LP, ICP > 200 mm H2O



BIH - 2

  • Female 20 - 50 yrs old and overweight

  • Ipsilateral IJV digital pressure subsides

  • Poss. blurred vision, fronto-occipital HA, lightheadedness-disequilibuium

  • Poss. LF HL with good discrimination, which nomalizes with IJV pressure



BIH - Treatment

  • Weight loss

  • Acetazolamide, furosemide

  • Subarachnoid-peritoneal shunt

  • Occas. gastric bypass for weight reduction



Vascular Neoplasms

  • Classic tumors - Glomus jugulare and tympanicum

  • Bruit not altered by neck pressure, head position, posture, or Valsalva

  • Tympanometry - regular perturbations

  • Otoscopy - bluish or redish mass poss. pulsation and paling with pos. pressure



Vascular Neoplasms - 2

  • Dif. Diag. - hemotympanum, dehiscent jugular bulb, carotid artery abnormality

  • Radiograph prior to mryingotomy

  • Check H & N for masses

  • Cranial nerve and cerebellar function

  • If suspected CT scan, mass in ME or eroded jugular spine.



Vascular Neoplasms - 3

  • Arteriography

  • MRI

  • Treatment is usually surgical



Arteriovenous Malformations

  • Developemental abnormalities

  • Often larger than symptoms suggest

  • May enlarge rapidly and tend to recur

  • May inpinge on adjacent structures

  • Posterior fossa occipital artery and transverse sinus AVM most common

  • AVM of mandible uncommon but notorious cause of tinnitus



AVM - 2

  • Carotid artery/cavernous sinus from trauma

  • Pulsatile tinnitus often initial complaint

  • HA, papilledema, bruit with thrill,

  • Heart rate may slow with compression



AVM - Treatment

  • Surgical

  • Preceeded by angiography with embolization

  • Tend to be larger than appear on angio.

  • Max benefit if surgery follows within 72 hrs



Venous Hum

  • Eddy currents in IJV

  • Normal in children, some adults, esp. young women

  • Attributed to Trans. proc. C2, increased CO (anemia, thyrotoxicosis, pregnancy)

  • Often presents with hearing loss



Venous Hum - 2

  • Gentle ant. neck pressure may relieve

  • Head toward univolved side decreases and to involved side increases

  • Deep breathing and Valsalva increase

  • Treat by reassurance, and correcting underlying cause



Palatomyoclonus

  • Irregular clicking sound, 20-400 bpm

  • Occurs intermittently

  • Palatal musculature and ET mucous membrane

  • Also ear fullness, hearing distortion

  • May have other muscle spasms

  • Diagnose with Toynbee tube in ear canal



Palatomyoclonus -2

  • Tympanogram movement synchronous with contraction

  • EMG of palatal muscles confirms

  • Observable palatal fasciculation - MRI

  • Hypertrophic degeneration inferior olive

  • Differentiate from tensor tympani spasm, usually transient



Palatomyoclonus -3

  • Treatment - clonazepam, diazepam, warm liquids, stress mgmt.

  • Botulinum toxin injection in severe cases



Idiopathic Stapedial Muscle Spasm

  • Rough, rumbling, or crackling noise

  • Triggered by external noises

  • Brief and intermittent

  • Rarely disruptive and prolonged

  • Variable intensity tympanometry to induce spasm



Idiopathic Stapedial Muscle Spasm - 2

  • Acoustic reflex - prolonged continued increased impedance during and after sound stimulus

  • Treatment - clonazepam, diazepam

  • Symptoms may last only months

  • Surgery to divide tendon as last resort



Subjective Tinnitus

  • Tinnitus originates within auditory system

  • More common

  • Little known about physiologic mechanism

  • Hyperactive hair cells or nerve fibers

  • Chemical imbalance

  • Reduced suppressive influence of CNS



Auditory Pathway

  • Cochlear hair cells, bipolar neurons of spiral ganglion make up 8th nerve, terminate on cochlear nucleus

  • Three pathways - dorsal acoustic stria, intermediate acoustic stria, trapezoid body

  • Superior olivary nuclei

  • Lateral lemniscus



Auditory Pathway - 2

  • Bilateral auditory input from outset

  • Central auditory lesions do not cause monoaural disability

  • Inferior colliculus arranged tonotopically

  • Medial geniculate body, ipsilateral

  • Primary Auditory Cortex, Sup. Temp. Gyrus (Brodmann’s areas 41 and 42)



Auditory Brainstem Response

  • Auditory evoked responses

  • Electrophysiologic recordings of response to sound

  • Can be recorded from all levels of auditory pathway

  • ABR most applied clinically

  • Waves from 8th nerve, caudal and rostral brainstem



ABR - 2

  • Wave I - synchronously stimulated compound action potentials from distal (cochlear) end of 8th nerve

  • Wave II - Also 8th nerve but near brainstem

  • Wave I & II - ipsilateral to ear stimulated

  • Later waves have multiple generators

  • Wave III - caudal pons with cont. cochlear nuclei, trapezoid body, sup. olivary complex



ABR - 3

  • Wave V - most prominent and rostral

  • Lateral lemniscus near inferior colliculus probably on contralateral side to ear stimulated

  • Little difference in ABR in tinnitus



Evaluation - Subjective Tinnitus

  • Etiologic factors - otologic, cardiovascular, metabolic, neurologic, pharmacologic, dental, psychological

  • H/O noise exposure and related symptoms - hearing loss, vertigo

  • Exact characterization of tinnitus quality

  • Perceptual location



Evaluation - Subjective Tinnitus

  • Head injury, whiplash injury, meningitis, multiple sclerosis

  • Medications - aspirin, aspirin compounds, aminoglycoside antbiotics, NSAIDS, heterocycline antidepressants

  • TMJ, dental abnormalities prevalent

  • Psychologic factors, somatoform disorder

  • Depression



Evaluation - Subjective Tinnitus

  • Audiometry - assymetrical hearing loss, unilateral tinnitus - MRI r/o post fossa

  • Complete questionnaire for perceived severity



Measurement of Tinnitus

  • Pitch, loudness, minimum masking level, residual inhibition/post masking

  • Minimum masking level most clinical use

  • Pitch - match most prominent pure tone, poor reliability, octave difference

  • Loudness - Adjust pure tone to tinnitus

  • Most < 7 dB SL, may be 2 dB



Measurement of Tinnitus

  • Minimal masking level - number of decibels to cover tinnitus

  • Residual inhibition - response of patients tinnitus post masking



Diagnostic Tests

  • None available to objectively measure or confirm tinnitus

  • ABR, PET, SpOAE, magnetic activity



Otoacoustic Emissions

  • Low-intensity sounds produced by cochlea as response to acoustic stimulus

  • Outer hair cell motility affects basilar membrane - intracochlear amplification, cochlear tuning

  • Generates mechanical energy propagated to ear canal

  • Vibration of TM produces acoustic signal measured by sensitive microphone



Spontaneous Otoacoustic Emissions

  • Measurable without stimulation

  • Present in 60% with normal hearing

  • Twice as common in females

  • No relationship yet in tinnitus



Distortion Product Otoacoustic Emissions

  • Produced when two pure-tone simuli, different frequency simultaneously

  • Present in all normal hearing

  • Damaged outer hair cells - no DPOAE

  • 30% damage without audiogram change

  • Will have abnormal OAE

  • No correlation in tinnitus yet



DPOAE

  • Norton - oscillating or prolonged evoked emission in 5/6 tinnitus patients and 0/2 without

  • They suggent that evoked emission and the tinnitus might be related to the same underlying pathology, but the former is not the cause of the latter



Tinnitus Treatment - Counseling

  • Etiologic factors

  • After work-up, unlikelihood of tumor or life-endangering disease

  • 25% improve or go away, 50% decrease, 25% persist, very small portion increase

  • Avoid loud noise, wear ear protection

  • Avoid caffeinated beverages, stimulants (coffee, tea, colas, chocolate)

  • Stop smoking



Tinnitus Treatement - Medication

  • Avoid previously mentioned medicines

  • Nicotinic acid (B6), carbamazepine, baclofen, others; none beneficial

  • Lidocaine beneficial - IV, short 1/2 life, poor side effects

  • Oral analogs - tocainide, flecainide acetate - no benefit



Tinnitus Treatment - Meds

  • Melatonin - 3.0 mg qhs does not relieve tinnitus

  • Sleep disturbance - 46.7% vs. 20% placebo benefit (p=0.04)

  • Benzodiazepines - clonazepam, oxazepam, alprazolam may provide benefit esp. with concurrent depression

  • Alprazolam - 76% had reduction in loudness 5% of placebo



Tinnitus Treatment - Meds

  • Overall, meds should not be major strategy, certain sufferers may benefit in conjuntion with other therapy



Environmental Masking

  • For mild tinnitus esp. bothersome in quiet

  • Home environmental maskers

  • Broad-band noise, between FM stations

  • Particularly useful at night

  • Required noise soft usually does not disturb family members



Hearing Aids and Maskers

  • Saltzmann and Ersner (1947) - hearing aids amplified background noise, mask tinnitus

  • If hearing loss try HA, less interference with speech, no noise to produce damage, improve speech understanding

  • Commercial tinnitus maskers with or without HA

  • Complete or partial mask

  • No clear guidelines for use



Hearing Aides and Maskers

  • Narrowband noise (less 1/2 octave) tonal character, more annoying

  • Conservative approach - lowest level with adequate relief, need not be worn continuously

  • No protocol which ear, unilateral, bilateral



Electrical Stimulation

  • DC (direct current) to round window or promontory could reduce tinnitus

  • DC may produce permanent damage, cannot be used clinically

  • AC (alternatig current)

  • External stim to tympanic membrane, transtympanically on promontory, tanscutaneously in pre and post auricular region



Electrical Stimulation

  • Ext. AC stim. results mixed, some promising

  • One commercial extracochlear wearable device marketed 1985

  • 1986 Dobie 1 in 20 benefited



Intracochlear Electrical Stimulation

  • Observations that cochlear-implant patients reduction in tinnitus while listening to speech

  • Few received CI explicitly for tinnitus

  • 1984 House 5 patients severe to profound HL, CI placed for tinnitus relief, no stim. only one reported benefit listening to speech.



Intracochlear Electrical Stimulation

  • 1989 Hazell - six totally deaf, CI implant and trials with sinusoidal stim.

  • Able to reduce tinnitus in all 6 with 100 Hz sinusoid

  • Two forego speech processor and used just for tinnitus relief

  • One turn on current, turn off tinnitus “like a light switch”



Surgery

  • Effective in treating conditions, tinnitus is symptom eg. otosclerosis, acoustic neuroma, glomus jugulare

  • Lituratue discusses cochlear neurectomy and microvascular decompression of the cochlear nerve

  • Results not consistent

  • Few otologists advocate use of surgery

  • Validates hypothesis tinnitus gen. central



Neurophysiological Approach to Tinnitus and Habituation

  • New theory

  • Previous theories share belief that process producing tinnitus restricted to auditory pathway and cochlea

  • Models focused on tinnitus generation, treated auditory pathway as passive, unchangeable transmitters of signal to auditory cortex



Neurophysiological Model

  • Diagnostic efforts concentrated on psychoacoustical description (loudness, pitch, maskability)

  • These no help in predicting treatment outcome, no explaination why same descript produced drastic different annoyance

  • This model postulates - tinnitus results from multiple interactions of a number of subsystems in nervous system



Neurophysiological Model

  • Auditory pathway role in development and appearance of tinnitus as sound perception

  • Other systems, limbic system, tinnitus annoyance

  • Problem - perception becomes associated with neg. emotions, fear , and threat

  • Limbic system activates autonomic nervous system resulting in annoyance



Neurophysiologic Model

  • Because annoyance primarily dependent on limbic system which is a perception by the individual and an associated emotional state, psychoacoustical characterization of tinnitus irrelevant



Habituation

  • Def. - The disappearance of reactions to sensory stimulus because of repetitive exposition of a subject to this stimulus and the lack of positive or negative reinforcement associated with this stimulus

  • Brain ordering of tasks 1) importance of signal esp. if danger 2) novelty

  • If signal not assoc. with event or indicate danger, not new, undergoes habituation, and after repetition in not perceived



Habituation

  • Accomplished by directive counseling - educate patient of potential mechanisms of tinnitus, discuss results of all audiologic and medical tests and relavance

  • Once patient understands, level of annoyance decreases

  • Repetative visits reinforce and eliminate negative association evoked by tinnitus



Habituation

  • Directive counseling essential but not sufficient to achieve permanent habituation

  • Need to enhance auditory background ie. partial masking, particularly in quiet envir.

  • Increased background spontaneous and evoked activity in auditory pathways, reduces contrast of tinnitus to background noise facilitating habituation

  • Must avoid masking tinnitus completely



Habituation

  • By def. once signal is masked it cannot be habituated to

  • Reconditioning of connections in subcortical centers cannot occur if stimulus (tinnitus) is absent

  • Tinnitus masking 15 yrs no changes in tinnitus, evidence of habituation, decreased annoyance

  • One year habituation therapy - aware only small percent of time, annoyance decreased



Habituation - Technique

  • Fitted binaurally with broad-band noise generator

  • Use for at least 6 hrs per day, part. in quiet

  • If HL, HA are also used

  • Process requires 12 months

  • Jastreboff insists 6 more months to ensure plastic changes in brain establised

  • After that time noise generators discontinued



Habituation - Results

  • Jabstreboff reports 83% of patients exhibit significant improvement with combined therapy



Summary

  • Important to differentiate types of tinnitus

  • Must recognize when tinnitus part of symptomatology of underlying disease verses merely auditory annoyance

  • Patience and understanding of patient’s experience important

  • Paraauditory tinnitus treatable by standard medical/surgical therapy

  • Subjective tinnitus treatment advancing




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