Tinnitus Aurium Dr Vishal Sharma History p Bewitched

Tinnitus Aurium Dr. Vishal Sharma

History p “Bewitched ear” in Ebers papyrus (3000 BC) p Tinnire (to ring) used by Pliny Elder, 23 -79 AD p Joseph Toynbee died in 1866 due to chloroform + prussic acid vapour inhalation as tx for tinnitus p Fowler (1941): performed frequency matching, loudness matching & tinnitus masking

Definition

p Conscious experience of a sound that originates in an involuntary manner in owner’s head with no corresponding external acoustic or electrical stimulus (Mc. Fadden, 1982) p Must persist for > 5 min at a time (Scott-Brown) p Due to aberrant spontaneous activity arising from altered state of excitation or inhibition within auditory system

Incidence p 6 - 17 % of people experience tinnitus p 3 - 7 % of people seek help for their tinnitus p 0. 5 - 2. 5 % report severe effects of tinnitus p Tinnitus present in: deafness (60 -85%), sudden SNHL (50%), NIHL (50 -90%), presbyacusis (70%), acoustic neuroma (70%), Meniere’s attack (100%)

Subjective vs. Objective tinnitus p Subjective (true) tinnitus: heard by patient only p Etiology = otological & non-otological p Objective (pseudo) tinnitus or somato-sounds: heard by patient & examiner with stethoscope p Etiology = vascular & non-vascular

Other associated Dysacusis p Hyperacusis = hypersensitivity to sound due to increased abnormal gain within auditory system p Phonophobia or Misophonia = hypersensitivity + fear toward sound stimulus due to abnormal excitation of limbic & autonomic nervous system

Otological subjective tinnitus Conductive causes Cochlear causes Impacted wax Presbyacusis Impacted foreign body Noise induced Otitis externa Meniere’s disease Otitis media Ototoxicity Otosclerosis Temporal bone trauma Labyrinthitis

Otological subjective tinnitus Retro-cochlear causes Central causes Acoustic neuroma Multiple sclerosis Other CPA lesions CVA Vascular compression CNS tumors of 8 th nerve Hydrocephalus

Non-Otologic Causes of Subjective Tinnitus

Temporo-mandibular joint disorders Cardiovascular: anemia, hypertension, Hypotension Metabolic: hypoglycemia, hypothyroidism, hyperlipidemia Neurologic: epilepsy, migraine, meningitis Withdrawal: alcohol, caffeine, anti-depressants, antihistamines Psychogenic: anxiety, depression

Vascular Causes of Objective Tinnitus

Arterio-venous shunts: congenital arterio-venous malformation, acquired AV shunt, caroticocavernous fistula Arterial bruits: aberrant ICA, aneurysm / stenosis of ICA, persistent stapedial artery Venous hum: dehiscent jugular bulb, Hypertension Paragangliomas: glomus jugulare / tympanicum

Objective Tinnitus (non-vascular causes) p Patulous Eustachian tube p Myoclonus: palatal, stapedial, tensor tympani p Clicking temporo-mandibular joint p Live foreign body in external auditory canal p Spontaneous oto-acoustic emissions

Models for Mechanisms of Tinnitus

Conductive tinnitus model Lack of ambient noise masking leads to enhancement or revealing of: p Sensori-neural tinnitus p Non-otological subjective tinnitus p Somato-sounds or objective tinnitus

Cochlear tinnitus model p Cochlear pathology abnormal spontaneous rate or rhythm of activity in cochlear nerve p Spontaneous oscillations of outer hair cells p Glutamate neuro-transmitter excito-toxicity p Enhanced sensitivity of receptors to glutamate & endogenous opioid peptides dynorphins

Neural Tinnitus Model p De-myelinization of cochlear nerve fibres cross-talk b/w nerve fibres distortion of resting state of discharge in nerve fibres p Lack of efferent auditory pathway inhibition (pathway dysfunction or GABA down regulation) p Calcium channel dysfunction ed intracellular calcium ed activity in cochlear nerve

Central tinnitus model p Abnormal central processing of peripheral neural activity mediated by neuro-transmitters glutamate, glycine & acetylcholine p Extra-lemniscal auditory activation by somatosensory, somato-motor & visual-motor systems p Tonotopic reorganization of auditory cortex

Trigger factors for tinnitus p Psychological stress (serotonin & adrenaline) p Noise exposure p Head injury, TM joint injury, neck injury p Ear syringing p Changes in atmospheric pressure p Surgical operations

Neuro-physiological model for tinnitus Proposed by Pawel Jastreboff in 1990

Conditioned reflex loops

Conditioned reflex loops p CRL develop b/w limbic system, ANS, subcortical pathways & auditory cortex p Concern & fear toward tinnitus negative reinforcement make CRLs strong p Once strong CRLs develop, peripheral auditory signals not necessary for tinnitus perception p Role of tinnitus retraining therapy: break these CRLs by natural habituation

Points in favour of Neuro-physiological model 1. Significant damage to auditory system not required for tinnitus to develop as 30% pt with tinnitus have normal hearing 2. 30% pt with hearing loss don’t have tinnitus 3. Tinnitus associated with emotional distress, sleep problems, anxiety & negative emotions, suggesting involvement of limbic system & ANS

History taking in Tinnitus patient

p Sleep disturbance / emotional upset p Pulsatile or persistent tinnitus p Does tinnitus get masked by ambient noise? p Deafness / vertigo / hyperacusis / phonophobia p Trauma: head / cervical spine / noise p Ototoxicity / withdrawal from drugs p Anxiety / depression p DM / HTN / thyroid disease / epilepsy / migraine

General Examination p Auscultation: for objective tinnitus p Pallor / hypertension / hypotension p Effect of neck turning on tinnitus p Effect of jugular vein compression on tinnitus p Temporo-mandibular joint mobility for clicks

E. N. T. examination 1. Otoscopy: for EAC pathology for spontaneous movement of T. M. p Synchronous with pulse: vascular somatosound p Synchronous with breathing: patulous E. T. p Synchronous with soft palate twitch: myoclonus 2. Tuning Fork Tests: conductive vs. SNHL

Investigations

p Pure Tone Audiometry: to assess hearing threshold & rule out hyperacusis p S. I. & A. B. L. B. : for cochlear deafness p T. D. T. : for retro-cochlear deafness p Impedance audiometry: Rule out otosclerosis Large fluctuations in compliance with respiration = patulous Eustachian tube p Otoacoustic emissions: for cochlear function p B. E. R. A. : for retro-cochlear pathology

p CT scan with contrast: for CPA & CNS tumours in unilateral tinnitus p Angiography: for vascular malformations, glomus tumours p Functional MRI & PET scan: tinnitus activates primary auditory (temporal) cortex, associative auditory (temporo-parietal) cortex, hippocampus, prefrontal-temporal network & limbic system

Psycho-acoustical measurement p Pitch or frequency matching of tinnitus p Loudness matching of tinnitus p Minimal masking level for tinnitus p Residual inhibition: temporary suppression or elimination of tinnitus following its masking

Other Investigations p CBP with ESR p Sugar profile: FBS, PPBS, RBS p Thyroid profile: T 3, T 4, TSH p Lipid profile: TG, LDL, HDL p Circulating auto-antibodies p Syphilis serology

Treatment Protocols p Prevention p Pathological conditions to be treated p Psychotherapy p Prosthetic: H. A. , C. I. , T. R. T. , tinnitus maskers (? ) p Pharmacological (? ) p Surgery (? ) p Stimulation ? : electrical, magnetic, electromagnetic p Others: Ginkgo biloba ? , acupuncture ? , yoga ?

Prevention / Avoidance of: p Viral infections p Noise induced hearing loss p Ototoxic drugs p Chocolate, cheese, tea, coffee, red wine p Rapid withdrawal of addictive substances

Tx of causative factors p Impacted wax p Otitis media p Meniere’s disease p Anemia p Hypertension & hypotension p Diabetes mellitus & hypoglycemia p Hypothyroidism & hyperthyroidism

Psychotherapy p Cognitive behavioral therapy aims at removing negative emotions due to tinnitus perception (cognitive therapy) & modification of tinnitus motivated avoidance behavior (behavior therapy) p Bio-feedback displays electro-myographic evidence of frontalis muscle tension due to tinnitus. Awareness helps in its removal.

Hearing aids & Cochlear Implants They help in pt with deafness + tinnitus by: p Reducing awareness of tinnitus by amplification of ambient sounds p Improved auditory input enhances central mechanism of habituation & promotes central adaptive plasticity

Tinnitus Maskers p Synonym: white noise generators p Complete masking: tinnitus becomes inaudible due to higher intensity of masking noise. Not used. Partial masking: provides low intensity background noise against which loudness of tinnitus gets reduced. Preferred technique. p Tinnitus masker + hearing aid = tinnitus instrument

Facts about tinnitus masking p total suppression (total masking) of tinnitus prevents tinnitus habituation p partial suppression (partial masking) does not prevent tinnitus habituation p activation of limbic & autonomic nervous systems by too loud or unpleasant sounds, enhances tinnitus & prevents habituation

Facts about tinnitus masking p low-level noise masking also enhances tinnitus (stochastic resonance ) p stochastic resonance range = 20 d. B, beginning from – 5 d. B below threshold of tinnitus detection p Ideal masking intensity = b/w stochastic resonance & total masking called “mixing point”

Ideal masking intensity

Tinnitus characteristics p Conductive: low-pitch, masked at auditory threshold p Cochlear: high-pitch (except Meniere’s disease), masked at auditory threshold p Retro-cochlear: high-pitch, masked well above auditory threshold p Central: high-pitch, resistant to masking

p Based on neuro-physiological model of tinnitus p Blocks tinnitus-related neuronal activity from reaching cerebral cortex (where it is perceived) & from activating limbic & autonomic nervous systems p Uses combination of low level, broad-band sound therapy & psychological counseling to achieve habituation of tinnitus. Tinnitus never masked in TRT. Retraining takes 12 -18 months. Success rate = 80%

Conditioned reflex loops

Effect of habituation by TRT

Pharmacological Treatment

Anti-depressants: p Amitryptiline = 25 mg TID for 3 weeks p Fluoxetine = 20 mg BD for 3 weeks G. A. B. A. analogues: p Alprazolam = 0. 25 – 0. 5 mg OD BD for 3 weeks p Clonazepam = 0. 5 – 1. 0 mg OD BD for 3 weeks p Gabapentin = 300 mg OD TID for 3 weeks p Baclofen = 10 mg BD 25 mg BD for 3 weeks

Calcium blocker: Nimodipine = 30 mg BD X 3 wk Glutamate blocker: Caroverine infusion Antiepileptics: p Carbamazepine = 100 mg BD 200 mg TID (3 wk) p Na Valproate = 200 mg TID 500 mg TID X 3 wk p Lamotrigine = 50 mg OD 100 mg BD X 3 wk Prostaglandin: Misoprostol = 200 μg QID X 3 wk Lignocaine: IV & trans-tympanic application

Surgical treatment p Surgical removal of vascular malformations p Surgical division of cochlear nerve p Micro-vascular decompression of anterior inferior cerebellar artery loop around auditory nerve Results of surgery for tx of tinnitus are poor & may actually worsen tinnitus

Stimulation of cochlea (? ) p Electrical: by round window or cochlear implant p Magnetic: by magnet placed in E. A. C. p Electro-magnetic: increases blood flow Spontaneous OAE suppression (? ) p Aspirin p Quinine

Treatment of Hyperacusis & Misophonia

Hyperacusis treatment p Attenuation of environmental sounds by ear plugs: temporary solution only for anticipated NIHL. Persistent use enhances hyperacusis p Hyperacusis desensitization therapy: using sound with higher frequencies removed (pink noise) give short exposures to moderately loud sound p Sound retraining therapy: like TRT Misophonia treatment: listening to music

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