Sandbox:tinnitus

## Pathophysiology of Subjective Tinnitus
One of the possible mechanisms relies in the otoacustic emissions. The inner ear contains thousands of minute hairs which vibrate in response to sound waves and cells which convert neural signals back into acoustical vibrations. The sensing cells are connected with the vibratory cells through a neural feedback loop, whose gain is regulated by the brain. This loop is normally adjusted just below onset of self-oscillation, which gains the ear spectacular sensitivity and selectivity. If something changes, it's easy for the delicate adjustment to cross the barrier of oscillation and tinnitus results. This can actually be measured by a very sensitive microphone outside the ear.
Other possible mechanisms of how things can change in the ear is damage to the receptor cells. Although receptor cells can be regenerated from the adjacent supporting Deiters cells after injury in birds, reptiles, and amphibians, in mammals it is believed that they can be produced only during embryogenesis.  Although mammalian Deiters cells reproduce and position themselves appropriately for regeneration, they have not been observed to transdifferentiate into receptor cells except in tissue culture experiments. Therefore, if these hairs become damaged, through prolonged exposure to excessive decibel levels, for instance, then deafness to certain frequencies occurs.  In tinnitus, they may falsely relay information at a certain frequency that an externally audible sound is present, when it is not.
The mechanisms of subjective tinnitus are often obscure. While it is not surprising that direct trauma to the inner ear can cause tinnitus, other apparent causes (e.g., temporomandibular joint disorder (TMJ) and dental disorders) are difficult to explain. Recent research has proposed that there are two distinct categories of subjective tinnitus: Otic tinnitus, caused by disorders of the inner ear or the acoustic nerve, and somatic tinnitus, caused by disorders outside the ear and nerve but still within the head or neck. It is further hypothesized that somatic tinnitus may be due to "central crosstalk" within the brain, as certain head and neck nerves enter the brain near regions known to be involved in hearing.
While most discussions of tinnitus tend to stress physical mechanisms, there is strong evidence that the level of an individual's awareness of their tinnitus can be stress-related, and so should be addressed by improving the state of the nervous system generally, using gradual, unobtrusive, long-term treatments. 

## Pathophysiology of Objective Tinnitus
In a minority of cases, a clinician can perceive an actual sound (e.g., a bruit) emanating from the patient's ears.  This is called  objective tinnitus.  Objective tinnitus can arise from muscle spasms that cause clicks or crackling around the middle ear.  Some people experience a sound that beats in time with the pulse (pulsatile tinnitus).  Pulsatile tinnitus is usually objective in nature, resulting from altered blood flow or increased blood turbulence near the ear (such as from atherosclerosis or venous hum), but it can also arise as a subjective phenomenon from an increased awareness of blood flow in the ear. Rarely, pulsatile tinnitus may be a symptom of potentially life-threatening conditions such as carotid artery aneurysm or carotid artery dissection.

## Causes in Alphabetical Order
- Acoustic neuroma
- Acoustic shock
- Acute otitis externa
- Acute otitis media
- Allergies
- Altitude sickness
- Amikacin
- Aminoglycoside
- Aminophylline
- Amphotericin B
- Anemia
- Angiotensin converting enzyme inhibitors
- Antibiotics
- Antimalarial drugs
- Anxiety
- Aortic regurgitation
- Arterial angioma
- Arteriosclerosis
- Aspirin
- Atherosclerosis of the carotid artery
- Auditory tube dysfunction
- Aural polyps
- Autoimmune inner ear disease
- Basilar artery migraine
- Benzodiazepines
- Bismuth
- Bleomycin
- Blocked eustachian tube
- Bumetanide
- Caffeine
- Calcium channel blockers
- Carbamazepine
- Carotico-cavernous fistula
- Carotid artery dissection
- Cerebral aneurysm
- Cerumen impaction
- Cervical spondylosis
- Chloramphenicol
- Chlordiazepoxide
- Chloroquine
- Cholesteatoma
- Cochlear trauma
- Chronic exposure to noise
- Chronic nephritis
- Chronic otitis media
- Chronic renal failure
- Chronic sinusitis
- Cisplatin
- Clarithromycin
- Clomifene
- Closed head injury
- Cogan syndrome
- Congenital intracranial aneurysm
- Costen syndrome
- Cox-2 inhibitors
- Cyclobenzaprine
- Cytomegalovirus
- Dapsone
- Depression
- Diabetes mellitus
- Diabetic vasculopathy
- Diflunisal
- Doxazosin
- Doxepin
- Dural arteriovenous fistula
- Ear infection
- Ear inflammation
- Earache
- Episodic ataxia type 2
- Erythromycin
- Ethacrynic acid
- Eustachian tube patency
- Excess coffee
- Febuxostat
- Fibromyalgia
- Fibrous dysplasia
- Fluid in the ear
- Fluoroquinolone
- Foreign body in ear
- Fosaprepitant
- Furosemide
- Gallium nitrate
- Gentamicin
- Glomus tumor
- Head injury
- Hearing loss
- Heart murmur
- Hydroxychloroquine
- Hypercholesterolemia
- Hypercoagulable states
- Hyperlipidemia
- Hyperparathyroidism
- Hypertension
- Hypertonia
- Hypnagogia
- Idiopathic
- Indomethacin
- Interferon
- Internal carotid thrombosis
- Isotretinoin
- Kanamycin
- Late-onset congenital hearing loss
- L-dopa
- Leukemia
- Lead poisoning
- Lidocaine
- Lincomycin hydrochloride
- Local anesthetic
- Loop diuretics
- Lyme disease
- Marijuana
- Measles
- Mechlorethamine
- Mefloquine
- Meniere's disease
- Meningitis
- Mercury poisoning
- Methotrexate
- Middle ear effusion
- Migraine
- Multiple sclerosis
- Nabilone
- Naltrexone
- Netilmicin
- Neuralgia
- Neurosyphilis
- Nitroprusside
- Nonsteroidal anti-inflammatory drugs
- Olsalazine
- Ossicle dislocation
- Osteogenesis imperfecta
- Otosclerosis
- Ototoxic medications
- Ototoxicity
- Oxcarbazepine
- Paget's disease of bone
- Pegylated interferon-alpha-2b
- Platinum-based chemotherapy
- Posterior cervical sympathetic syndrome
- Prazosin
- Presbyacusis
- Propranolol
- Proton pump inhibitors
- Pseudotumor cerebri
- Psychological disorders
- Quinidine
- Rheumatoid arthritis
- Rifaximin
- Rizatriptan
- Rubella
- Salicylates
- Sarcoid
- Sertraline
- Sibutramine
- Sickle cell anemia
- Skull fracture
- Sleep paralysis
- Small vessel disease
- Stroke
- Sulfasalazine
- Sulindac
- Suppurative labyrinthitis
- Susac syndrome
- Syphilitic disease
- Systemic lupus erythematosus
- Temozolomide
- Temporomandibular joint disorder
- Tetracycline
- Thalidomide
- Thoracic outlet syndrome
- Thyroid disease
- Tolbutamide
- Tolmetin
- Toluene
- Tricyclic antidepressants
- Tumor
- Tympanic membrane perforation
- Typhoid
- Uremia
- Valproic acid
- Vancomycin
- Vascular malformations
- Vascular tumors
- Venous hum
- Vincristine
- Vitamin B12 deficiency
- Vogt-Koyanagi-Harada syndrome
- Whiplash injury

# Common Causes of Tinnitus
- Otologic problems and hearing loss:
Conductive hearing loss
External ear infection
Acoustic shock
Cerumen (earwax) impaction
Middle ear effusion
Sensorineural hearing loss
Excessive or loud noise
Presbycusis (age-associated hearing loss)
Meniere's disease
Acoustic neuroma
mercury or lead poisoning
Ototoxic medications
Analgesics:
Aspirin
Nonsteroidal anti-inflammatory drugs
Diflunisal
Sulindac
Antibiotics:
Aminoglycosides  e.g. gentamicin
Chloramphenicol
Erythromycin
fosaprepitant
Imipenem-Cilastatin
Lincomycin Hydrochloride
Rifaximin
Sulfasalazine
Tetracycline
Vancomycin
Chemotherapy and antiviral drugs:
Nabilone
Bleomycin
Gallium nitrate
Interferon
Pegylated interferon-alpha-2b
Cisplatin
Mechlorethamine
Methotrexate
Vincristine
Loop diuretics:
Bumetanide
Ethacrynic acid
Furosemide
Others:
Capreomycin sulfate
Chloroquine
Clomifene
Dapsone
Febuxostat
Quinine
Hydroxychloroquine
Naltrexone
Olsalazine
Oxcarbazepine
Rizatriptan
Thalidomide
Tolmetin
- Conductive hearing loss
External ear infection
Acoustic shock
Cerumen (earwax) impaction
Middle ear effusion
- External ear infection
- Acoustic shock
- Cerumen (earwax) impaction
- Middle ear effusion
- Sensorineural hearing loss
Excessive or loud noise
Presbycusis (age-associated hearing loss)
Meniere's disease
Acoustic neuroma
mercury or lead poisoning
Ototoxic medications
Analgesics:
Aspirin
Nonsteroidal anti-inflammatory drugs
Diflunisal
Sulindac
Antibiotics:
Aminoglycosides  e.g. gentamicin
Chloramphenicol
Erythromycin
fosaprepitant
Imipenem-Cilastatin
Lincomycin Hydrochloride
Rifaximin
Sulfasalazine
Tetracycline
Vancomycin
Chemotherapy and antiviral drugs:
Nabilone
Bleomycin
Gallium nitrate
Interferon
Pegylated interferon-alpha-2b
Cisplatin
Mechlorethamine
Methotrexate
Vincristine
Loop diuretics:
Bumetanide
Ethacrynic acid
Furosemide
Others:
Capreomycin sulfate
Chloroquine
Clomifene
Dapsone
Febuxostat
Quinine
Hydroxychloroquine
Naltrexone
Olsalazine
Oxcarbazepine
Rizatriptan
Thalidomide
Tolmetin
- Excessive or loud noise
- Presbycusis (age-associated hearing loss)
- Meniere's disease
- Acoustic neuroma
- mercury or lead poisoning
- Ototoxic medications
Analgesics:
Aspirin
Nonsteroidal anti-inflammatory drugs
Diflunisal
Sulindac
Antibiotics:
Aminoglycosides  e.g. gentamicin
Chloramphenicol
Erythromycin
fosaprepitant
Imipenem-Cilastatin
Lincomycin Hydrochloride
Rifaximin
Sulfasalazine
Tetracycline
Vancomycin
Chemotherapy and antiviral drugs:
Nabilone
Bleomycin
Gallium nitrate
Interferon
Pegylated interferon-alpha-2b
Cisplatin
Mechlorethamine
Methotrexate
Vincristine
Loop diuretics:
Bumetanide
Ethacrynic acid
Furosemide
Others:
Capreomycin sulfate
Chloroquine
Clomifene
Dapsone
Febuxostat
Quinine
Hydroxychloroquine
Naltrexone
Olsalazine
Oxcarbazepine
Rizatriptan
Thalidomide
Tolmetin
- Analgesics:
Aspirin
Nonsteroidal anti-inflammatory drugs
Diflunisal
Sulindac
- Aspirin
- Nonsteroidal anti-inflammatory drugs
- Diflunisal
- Sulindac
- Antibiotics:
Aminoglycosides  e.g. gentamicin
Chloramphenicol
Erythromycin
fosaprepitant
- Aminoglycosides  e.g. gentamicin
- Chloramphenicol
- Erythromycin
- fosaprepitant
- Imipenem-Cilastatin
Lincomycin Hydrochloride
Rifaximin
Sulfasalazine
Tetracycline
Vancomycin
- Lincomycin Hydrochloride
- Rifaximin
- Sulfasalazine
- Tetracycline
- Vancomycin
- Chemotherapy and antiviral drugs:
Nabilone
Bleomycin
Gallium nitrate
Interferon
Pegylated interferon-alpha-2b
Cisplatin
Mechlorethamine
Methotrexate
Vincristine
- Nabilone
- Bleomycin
- Gallium nitrate
- Interferon
- Pegylated interferon-alpha-2b
- Cisplatin
- Mechlorethamine
- Methotrexate
- Vincristine
- Loop diuretics:
Bumetanide
Ethacrynic acid
Furosemide
- Bumetanide
- Ethacrynic acid
- Furosemide
- Others:
- Capreomycin sulfate
Chloroquine
Clomifene
Dapsone
Febuxostat
Quinine
Hydroxychloroquine
Naltrexone
Olsalazine
Oxcarbazepine
Rizatriptan
Thalidomide
Tolmetin
- Chloroquine
- Clomifene
- Dapsone
- Febuxostat
- Quinine
- Hydroxychloroquine
- Naltrexone
- Olsalazine
- Oxcarbazepine
- Rizatriptan
- Thalidomide
- Tolmetin
- Neurologic disorders:
Multiple sclerosis
Head injury
Skull fracture
Closed head injury
Whiplash injury
Temporomandibular joint disorder
- Multiple sclerosis
- Head injury
Skull fracture
Closed head injury
Whiplash injury
Temporomandibular joint disorder
- Skull fracture
- Closed head injury
- Whiplash injury
- Temporomandibular joint disorder
- Metabolic disorders:
Thyroid disorder
Hyperlipidemia
Vitamin B12 deficiency
- Thyroid disorder
- Hyperlipidemia
- Vitamin B12 deficiency
- Psychogenic disorders:
Depression
Anxiety
- Depression
- Anxiety
- Other causes:
Fibromyalgia
Hypertonia (Muscle Tension)
Thoracic outlet syndrome
Lyme disease
Hypnogogia
Sleep paralysis
- Fibromyalgia
- Hypertonia (Muscle Tension)
- Thoracic outlet syndrome
- Lyme disease
- Hypnogogia
- Sleep paralysis
Tinnitus can be perceived in one or both ears or in the head. It is usually described as a ringing noise, but in some patients it takes the form of a high pitched whining, buzzing, hissing, humming, or whistling sound, or as ticking, clicking, roaring, "crickets" or "locusts", tunes, songs, or beeping. It has also been described as a "whooshing" sound, as of wind or waves.  Tinnitus is not itself a disease but a symptom resulting from a range of underlying causes, including ear infections, foreign objects or wax in the ear, and injury from loud noises. Tinnitus is also a side-effect of some oral medications, such as aspirin, and may also result from an abnormally low level of serotonin activity.
The sound perceived may range from a quiet background noise to one that can be heard even over loud external sounds.  The term "tinnitus" usually refers to more severe cases.  Heller and Bergman (1953) conducted a study of 80 tinnitus-free university students placed in a soundproofed room found that 93% reported hearing a buzzing, pulsing or whistling sound.  Cohort studies have demonstrated that damage to hearing (among other health effects) from unnatural levels of noise exposure is very widespread in industrialized countries.
Because tinnitus is often defined as a subjective phenomenon, it is difficult to measure using objective tests, such as by comparison to noise of known frequency and intensity, as in an audiometric test.  The condition is often rated clinically on a simple scale from "slight" to "catastrophic" according to the practical difficulties it imposes, such as interference with sleep, quiet activities, or normal daily activities.  For research purposes, the more elaborate Tinnitus Handicap Inventory is often used.

## Physical examination
The ears should be examined for wax and a foreign body.

## Measuring tinnitus
The basis of quantitative measurement of tinnitus relies on the brains tendency to select out only the loudest sounds heard. Based on this tendency, the amplitude of a patient's tinnitus can be measured by playing sample sounds of known amplitude and asking the patient which he or she hears. The tinnitus will always be equal to- or less than sample noises heard by the patient. This method works very well to gauge objective tinnitus (see above.) For example: if a patient has a pulsatile paraganglioma in his ear, he will not be able to hear the blood flow through the tumor when the sample noise is 5 decibels louder than the noise produced by the blood. As sound amplitude is gradually decreased, the tinnitus will become audible, and the level at which it does so provides an estimate of the amplitude of the objective tinnitus.
Objective tinnitus, however, is quite uncommon. Often patients with pulsatile tumors will report other coexistent sounds, distinct from the pulsatile noise, that will persist even after their tumor has been removed. This is generally subjective tinnitus, which, unlike the objective form, cannot be tested by comparative methods.
If a subject is focused on a sample noise, they can often detect it to levels below 5 decibels, which would indicate that their tinnitus would be almost impossible to hear. Conversely, if the same test subject is told to focus only on their tinnitus, they will report hearing the sound even when test noises exceed 70 decibels, making the tinnitus louder than a ringing phone. This quantification method suggests that subjective tinnitus relates only to what the patient is attempting to hear. Patients actively complaining about tinnitus could thus be assumed to be people who have become obsessed with the noise. This is only partially true. The problem is involuntary; generally complaining patients simply cannot override or ignore their tinnitus. The noise is often present in both quiet and noisy environments, and can become quite intrusive to their daily lives.
Subjective tinnitus may not always be correlated with ear malfunction or hearing loss. Even people with near-perfect hearing may still complain of it. Tinnitus may also have a connection to memory problems, anxiety, fatigue or a general state of poor health.
There are many treatments that are effective for objective tinnitus. But there are no clear effective treatments for subjective tinnitus.  Conversely, tinnitus may resolve without any treatment. In the subjective tinnitus the treatment of the associated problems like fatigue, anxiety and a bad healthy status is essential to achieve success. Effective treatments include:
Objective tinnitus:
- Gamma knife radiosurgery (glomus jugulare)
- Shielding of cochlea by teflon implant
- Botulinum toxin (palatal tremor)
- Propranolol and clonazepam (arterial anatomic variation)
Subjective tinnitus:
- Drugs and nutrients
Lidocaine, injection into the inner ear found to surpress the tinnitus for 20 minutes, according to a Swedish study. 
Benzodiazepines (xanax, ativan, klonopin)
Avoidance of caffeine, nicotine, salt
Avoidance of or consumption of alcohol
Zinc supplementation (where serum zinc deficiency is present)
Acamprosate
Etidronate or sodium fluoride (otosclerosis)
Lignocaine or anticonvulsants (usually in patients responsive to white noise masking)
Carbemazepine
Melatonin (especially for those with sleep disturbance)
Sertraline
Vitamin combinations (lipo-flavonoid)
- Lidocaine, injection into the inner ear found to surpress the tinnitus for 20 minutes, according to a Swedish study. 
- Benzodiazepines (xanax, ativan, klonopin)
- Avoidance of caffeine, nicotine, salt
- Avoidance of or consumption of alcohol
- Zinc supplementation (where serum zinc deficiency is present)
- Acamprosate
- Etidronate or sodium fluoride (otosclerosis)
- Lignocaine or anticonvulsants (usually in patients responsive to white noise masking)
- Carbemazepine
- Melatonin (especially for those with sleep disturbance)
- Sertraline
- Vitamin combinations (lipo-flavonoid)
- Electrical stimulation
Transcranial magnetic stimulation or transcranial direct current stimulation
Transcutaneous electrical nerve stimulation
Direct stimulation of auditory cortex by implanted electrodes
- Transcranial magnetic stimulation or transcranial direct current stimulation
- Transcutaneous electrical nerve stimulation
- Direct stimulation of auditory cortex by implanted electrodes
- Surgery
Repair of perilymph fistula
- Repair of perilymph fistula
- External sound
Low-pitched sound treatment has shown some positive, encouraging  results.(UC, Irvine press release)
Tinnitus masking (white noise)
Tinnitus retraining therapy
Auditive stimulation therapy (music therapy)
Compensation for lost frequencies by use of a hearing aid.
Ultrasonic bone-conduction external acoustic stimulation
Avoidance of outside noise (exogenous tinnitus)
- Low-pitched sound treatment has shown some positive, encouraging  results.(UC, Irvine press release)
- Tinnitus masking (white noise)
- Tinnitus retraining therapy
- Auditive stimulation therapy (music therapy)
- Compensation for lost frequencies by use of a hearing aid.
- Ultrasonic bone-conduction external acoustic stimulation
- Avoidance of outside noise (exogenous tinnitus)
- Psychological
Cognitive behavior therapy
- Cognitive behavior therapy
- Light-based
Photobiomodulation (a.k.a. Low Level Laser Therapy); efficacy is debated
- Photobiomodulation (a.k.a. Low Level Laser Therapy); efficacy is debated
Although there are no specific cures for tinnitus, anything that brings the person out of the "fight or flight" stress response helps symptoms recede over a period of time. Calming body-based therapies, counseling and psychotherapy help restore well-being, which in turn allows tinnitus to settle. Chronic tinnitus can be quite stressful psychologically, as it distracts the affected individual from mental tasks and interferes with sleep, particularly when there is no external sound. Additional steps in reducing the impact of tinnitus on adverse health consequences include: a review of medications that may have tinnitus as a side effect; a physical exam to reveal possible underlying health conditions that may aggravate tinnitus; receiving adequate rest each day; and seeking a physician's advice concerning a sleep aid to allow for a better sleep pattern.

# Related Chapters
- Absolute threshold of hearing
- Auditory system
- Audiologist
- Ear
- Hearing impairment
- Hyperacusis
- Noise health effects