Tinnitus – Causes, Symptoms, Diagnosis, Treatment

Tinnitus is defined as a sound a person hears that is generated by the body, rather than by outside source. Most tinnitus is subjective. This means the examiner cannot hear it, and there are no tools to measure or hear that sound. Objective tinnitus can arise from an aneurysm. This can be objectified and heard by the examiner. Other objective tinnitus investigation includes temporomandibular joint disease (TMJD) and tensor tympani muscle spasm.[rx][rx][rx][rx]

Tinnitus is defined as a phantom auditory perception-it is a perception of sound without corresponding acoustic or mechanical correlates in the cochlea.^[rx] Tinnitus is the perception of sound that does not originate from a source external to the individual’s body. When discussing tinnitus, it is first crucial to categorize it between either subjective or objective, as well as between pulsatile and non-pulsatile tinnitus. In subjective tinnitus, which is more common, only the patient can perceive the sound. On the other hand, in objective tinnitus, both the individual and potentially the examiner can hear the sound. For example, subjective tinnitus is classically caused by a sensorineural hearing loss in patients experiencing presbycusis. The examiner is not able to perceive the tinnitus; however, the patient can.[rx][rx][rx][rx]

Pathophysiology

When there is a danger or threat, humans normally react with typical fight or flight response. This is the reason why the onset of tinnitus can be so distressing. A broken finger does not necessarily trigger this response, but tinnitus does. Cognitive therapy is done to stop the unwanted reaction.

However, stress is not a cause of tinnitus. Because humans cannot objectify tinnitus, the pathophysiology is not understood. Lesions that put pressure on the eighth cranial nerve may cause tinnitus. An increase in fluid pressure in the inner ear causes tinnitus. Symptoms associated with increased inner ear pressure include hearing loss, vertigo, tinnitus, and feeling of pressure in the ear. MRI shows that many areas of the brain are involved in tinnitus including the cognitive and emotional areas, as well as the auditory. Sound first enters the brain via the amygdala center. Therefore, learning that tinnitus is not a danger is therapeutic.

Types of Tinnitus

Based on the outcomes of the doctor’s examination, he or she will determine which type of tinnitus you have. Doctors distinguish between the following types of tinnitus:

• Subjective and objective tinnitus – Subjective tinnitus can only be heard or perceived by the person who has it. Possible causes include problems with the auditory (hearing) system or the nerves that belong to it. In objective tinnitus, which is very rare, the doctor can hear the sounds too or detect the nerve signals causing the sounds. This is the case with tinnitus that is caused by blood-vessel-related problems, for instance. Here the doctor can hear a pulsing noise in the carotid artery in the neck with the help of a stethoscope.
• Primary and secondary tinnitus – If no clear cause can be found, it is referred to as primary tinnitus or idiopathic tinnitus. If there is an identifiable cause, it is known as secondary tinnitus. Possible causes include a perforated eardrum or a vascular (blood vessel) disease.
• Acute and chronic tinnitus – If the sounds last longer than three months, it is considered to be chronic tinnitus.
• Various levels of severity – Tinnitus can be mild and hardly affect your everyday life, or only occur from time to time but then be distressing when it does. Sounds that are constantly and clearly heard are more serious: They can have a big impact on your daily life and work, for instance, because it is hard to sleep and concentrate properly.

Causes of Tinnitus

There are many causes of tinnitus

• The most common cause of subjective tinnitus is noise trauma – For example, an employee who works in a noisy industry loses hearing at the 4000 Hz tone. Now the employee hears a sound which is similar to the 4000 tones.
• Metabolic diseases – Heart, hypertension, diabetes are associated with an onset of tinnitus. Various drugs are ototoxic to some individuals or at sufficient doses. For example, high doses of aspirin cause tinnitus, and the issue resolves when aspirin is stopped.
• Ear diseases – cause tinnitus including Meniere disease or lesions affecting the eighth cranial nerve.
• Blocked ear (auditory) – canal due to a build-up of ear wax
• Chronic middle ear infection
• A ruptured (perforated) eardrum
• Otosclerosis – a bone disease in the middle ear and inner ear that can lead to hearing loss
• Ménière’s disease – a disease of the inner ear, causing symptoms such as tinnitus, vertigo and hearing loss
• Problems affecting the muscles or joint of the jaw

Twenty percent of persons visiting tinnitus clinics have normal hearing. Some have somatosensory tinnitus. Here, stimulation from cervical or TMJD has activated the dorsal cochlear nucleus and sends impulses to the auditory center. Evidence for this is that stimulation similar to whiplash or TMJD has been shown to cause anatomical changes in the dorsal cochlear nucleus.[rx][rx][rx]

Diagnosis of Tinnitus

History and Physical

A physical exam should focus on the ear and the nervous system. The ear canal should be inspected for discharge, foreign body, and cerumen. The tympanic membrane should be inspected for signs of infection and tumor (red or bluish mass). A bedside hearing test should be done. Cranial nerves, particularly vestibular function, are tested along with peripheral strength, sensation, and reflexes. A stethoscope should be used to listen for vascular noise over the course of the carotid arteries and jugular veins and over and adjacent to the ear.

Evaluation

• X-rays – are not usually done for tinnitus unless there is an unexplained difference in hearing and balance in the ears.
• An audiogram – is a hearing test measuring hearing levels to determine hearing loss. The patient is asked to match which of the tones matches their tinnitus. The audiologist introduces that sound as to volume, and the patient estimates how loud they hear their tinnitus. Hearing via the bone of the ear is tested and compared with the hearing via the earphone called an air-bone test. If the patient hears better with the bone test, this suggests a condition called otosclerosis which is treatable. Patients with otosclerosis, in whom the stapes fail to move well, can have surgery that corrects the otosclerosis and restores air conduction. In some patients, the tinnitus is relieved. In others, tinnitus remains or becomes worse.
• The audiologist – measures how long tinnitus is relieved by masking tone. The longer the tinnitus is inhibited, the better the prognosis.[rx][rx][rx]
• Dopplers – should be ordered for suspected arterial etiologies such as carotid stenosis before ordering more advanced radiological studies. In general, both CT and MRI are complementary imaging modalities to identify vascular etiologies of pulsatile tinnitus. Suspected arterial etiologies not well defined by duplex should get a CTA. CTA may also identify aneurysms, which may manifest as pulsatile tinnitus. MRV better evaluates venous etiology. CT scan – It is appropriate to get a CT of the temporal bones if there is clinical suspicion for temporal bone pathology. Patients with focal nerve deficits are candidates for brain imaging, either CT or MRI, to evaluate for more serious causes of pulsatile tinnitus.[rx][rx] Other conditions may require further evaluation by specialists such as IIH, which can be diagnosed by normal brain CT/MRI and increased opening pressure on lumbar puncture. Performing an optic exam on these patients may reveal papilledema.

Treatment of Tinnitus

Non-Pharmacological

The American Academy of Otolaryngology has issued clinical practice guidelines for tinnitus. These include:

• Stress Reduction – This includes using biofeedback, measured breathing, etc. Although stress itself is not a cause of tinnitus, as in any condition, stress and anxiety can make the condition worse.
• Cognitive Therapy – The more the patient understands what tinnitus is and is not the less negative effect. Once the patient fully cognizes – understands that tinnitus is similar to itching, the symptoms are reduced.
• Sleep improvement – Tinnitus can affect normal sleep and therapy should be directed to better sleep hygiene.
• Masking – When the body hears the same sound from the cell phone or sound device, this reduces the symptoms.  There are various forms of masking. Essentially these masking sounds take the attention away from the internal tinnitus sound and replace it with relaxing sounds.

1. Introduction of the same sound
2. Introduction of an altered sound
3. Music with the tinnitus sound removed
4. White noise or pleasant sounds

Medication

• Magnesium, alpha-lipoic acid, N-acetyl cysteine – and others have been tested for protection of hearing from noise. When these are effective, it is difficult to differentiate from the placebo effect or from the impact of having a program where the patient feels they are in charge of bringing the brain into the healing process. Recently beneficial results have been reported using deep brain stimulation. In theory, this alters unwanted neural circuits.
• Alprazolam  – Medication such as alprazolam can reduce symptoms, but can have adverse effects including habituation.
• Anti-depressants – may be indicated for patients who do not respond to protocol therapy.[rx][rx]
• Carbamazepine – (Tegretol is a registered trademark) This drug is an oral anticonvulsant and mild antidepressant that is best known in this country for its effective use on trigeminal and glossopharyngeal neuralgia; in Europe, it has been used extensively against epilepsy.
• Lidocaine – (also known as lignocaine; Xylocaine is a registered trademark) Several recent reports indicate a high rate of improvement in tinnitus following the administration of lidocaine. This amide is commonly used as a local anesthetic in surgery of the middle ear and upper respiratory tract, but it is also a potent short-term anticonvulsant that has vasodilation as one of its effects.
• Niacin – A member of the vitamin B complex, niacin has three common forms—niacinamide, nicotinic acid, and nicotinamide. The amino acid tryptophan can also be converted into niacin by the body. Niacin is a peripheral vasodilator and thus has been used in the treatment of peripheral vascular disorders and migraine headaches. It also has a long history in the treatment of some forms of Meniere’s Disease.
• Vitamin A – Graham provides a summary of the studies concerned with vitamin A therapy. The early reports of both reductions in tinnitus and improvements in hearing sensitivity following massive intramuscular injection of vitamin A were not confirmed in later studies, and the issue seems to have been dropped.
• Tocainide Hydrochloride – (Toward is a registered trademark) Unlike lidocaine itself, which must be administered intravenously, this analog of lidocaine can be taken orally because of a difference in its metabolism by the liver. Additional attractions are that it has a physiological half-life of about 11 hours as compared to about 1.5 hours for lidocaine, and it has fewer side effects. Tocainide is currently being used experimentally as an oral antiarrhythmic agent in cardiac patients.
• Phenytoin Sodium – (also known as diphenylhydantoin; Dilantin is a registered trademark) This drug is an oral anticonvulsant similar in action to carbamazepine. In the paper discussed above, a brief mention is also made of Dilantin. It was apparently used on four patients who developed an allergic reaction to carbamazepine, but the only indication as to how these patients fared in the comment that Dilantin is always less effective than carbamazepine in treating tinnitus. Shea and Harell reported that none of 15 patients treated with this drug had any relief from tinnitus, even though all had some relief from the lidocaine injection.
• Primidone – (Mysoline is a registered trademark) This anticonvulsant has been tried against trigeminal neuralgia with mixed results. Emmett and Shea briefly mention a study of its effectiveness against tinnitus. Patients initially received 250 mg twice daily; the dosage was increased monthly in increments of 250 mg/day up to a maximum of 2 g/day or until the tinnitus was relieved. Details are few, but apparently 27 percent (11/41) of the patients reported 80–100 percent relief, and an additional 59 percent (24/41) reported 20–80 percent relief from their tinnitus. Exactly when in the regimen these judgments were made is not revealed, yet this appears to be an important issue given the high incidence of side effects reported.
• Sodium Fluoride – This compound has come to be recognized for its ability to reverse the process of demineralization in the cochlear capsule that leads to the condition of otospongiosis. Since this condition is often accompanied by a sensorineural-type hearing loss and by tinnitus and vertigo, it is of theoretical as well as practical interest here that these latter symptoms are often diminished or abolished as the otospongiosis is reversed. The explanation offered is that the otospongiotic focus gives off cytotoxic enzymes that then enter the perilymph, causing deterioration of cochlear elements critical to the normal transduction process, and, as a side effect, producing concomitant tinnitus. The administration of sodium fluoride cannot reverse the hearing loss (although according to Shambaugh it does arrest it), but it can eliminate the tinnitus and vertigo.
• Sodium Valproate – (Depakene, Epilim, and Ergenyl are registered trademarks) Goodey (1981) briefly mentions this drug, indicating that it reduces tinnitus in about the same proportion of subjects as does carbamazepine, but that, at the doses used to date, the amount of relief experienced is less than with carbamazepine. Apparently side effects are minor.
• Sodium Amylobarbitone – Noting a relationship between drugs that are effective on trigeminal neuralgia and on tinnitus (e.g., carbamazepine), Donaldson (1978) selected this fast-acting barbiturate, known for its effectiveness on trigeminal neuralgia, for a study on tinnitus. Forty patients with tinnitus of varying severity were randomly assigned to the experimental or control groups. Prior to treatment, all patients were assessed audio metrically, were asked to match the pitch and loudness of their tinnitus, and were asked to rate their tinnitus on a four-point scale (from “only noticeable in quiet environments” to “interferes with sleep, and patient engages in some activity to distract attention from it”). The experimental group was then put on a regimen of 50 mg in the morning, 50 mg in the early afternoon, and 80 mg at night; tinnitus was reassessed after 6 and 12 weeks. The drug was withdrawn after 12 weeks, and a final assessment was made at 18 weeks.
• Arlidin a vasodilator, and chlortrimeton an antihistamine – have been used singly and in combination with some success against some forms of tinnitus.
• Nortriptyline – Goodey indicates that the tricyclics, especially nortriptyline, may be worth investigating as tinnitus-reducing agents.
• Diazepam (Valium) – is surely one of the most widely prescribed drugs for tinnitus and its psychological concomitants, but Goodey says that there is no evidence that it has any value in this regard, and it can make depressed patients worse.
• Mexiletine – McCormick, and Thomas utilized a double-blind cross-over design in a study of mexiletine—a pharmacological relative of lidocaine that has an oral form. The patients’ numerical estimates of the severity of their tinnitus were unaffected both by this drug and by the placebo. It has been asserted that barbiturates do not cause tinnitus and it has been suggested that the aminoglycosides may produce only temporary tinnitus.
• Heparin – is reported to have produced temporary relief from tinnitus in a number of heart patients
• Trowbridge injected a 5 percent solution of ethylmorphine hydrochloride – an analgesic and vasodilator—directly through the tympanic membranes of patients suffering from tinnitus that he judged to be caused by structures of the middle ear (the tympanic plexus). He injected repeatedly at 4-day intervals and claimed reduction or elimination of tinnitus for the majority of patients so treated. He also claimed improved audiometric measures. No recent application of these procedures was found.
  A hearing aid – is always of benefit when tinnitus is associated with hearing loss. Some aids come with built-in soothing or masking sounds. Success is variable.