family practice grand rounds

Noise-Induced Hearing Loss: A Preventable Occupational Disease

Nicholas G. Alexiou, MD, MPH, Tom Gladfelter, MD, and Carmelo Saraceno, MD Tampa, Florida R. TOM GLADFELTER (Assistant Professor, Acoustic trauma occurs in the wedge-shaped organ D Department of Family Medicine): Hearing loss is of Corti in the cochlea of the ear. This structure, rest­ a common problem encountered in the practice of ing on the basilar membrane, has three outer rows and family physicians. We tend to consider hearing loss in one inner row of hair cells with the tectorial membrane a majority of patients to be due to the aging process, suspended above them. The hair cells have stereocilia but this is not always true. Hearing loss is often due to projecting toward the tectorial membrane. The energy a variety or combination of causes, which may require of sound causes vibration of these cilia; this vibration multiple disciplinary approaches for the diagnosis and is then coded into nerve impulses in the acoustic nerve management, particularly for hearing loss suspected to located beneath the hair cells. These hair cells are be noise induced and related to employment. Under quite susceptible to the trauma of loud noise. Noise- this circumstance, the patient, the employer, the induced anatomic changes are seen in the cell bodies, community, and the law courts are involved in the which swell and eventually are destroyed.1-3 Once de­ proper evaluation and disposition of the case in an stroyed, they are lost forever, leading to loss of func­ interrelated fashion. Noise-induced hearing loss is the tion. It is known that sound frequencies in the 1,000- to kind of health problem that the family physician can 4,000-Hz range are transmitted best to the cochlea, contribute to preventing in an important way, from which partially explains the typical finding of greatest acting as advisor to the patient (who is frequently the loss of hearing acuity at 4,000 Hz in acoustic trauma.3 employee) for his personal health care to acting as ad­ Since the mid-1800s work-related hearing loss has visor to the employer in the administration and super­ been recognized by state legislators, who have set limi­ vision of planning a hazard-free work environment. tations to noise exposure. Federal legislation was Without full awareness of all possible ramifications passed creating the Noise Control Act of 1972. At­ and without careful planning, it is possible for physi­ tempts to publish a standard for noise control and hear­ cians to provide less than optimal management of a ing conservation programs for workers’ health and case and find themselves caught in a legal dispute. In safety have long been frustrated by a variety of interest the following discussion, we will focus on noise- groups. The Occupational Safety and Health Adminis­ induced hearing loss (NIHL) related to occupation or tration (OSHA) estimates that 1 million workers have work exposure. noise-induced hearing loss in the United States.4 Re­ Dr. Alexiou, the Director of the Regional Center for cently OSHA issued a final ruling requiring hearing Occupational Safety and Health at the University of conservation programs in work places.5 Effective South Florida College of Medicine, will provide a April 7, 1983, the ruling required employers to ad­ briefing on the basics of noise trauma and the require­ minister a hearing conservation program when em­ ments of law. ployee noise exposure equaled or exceeded an 8-hour DR. NICHOLAS ALEXIOU (Assistant Professor, time-weighted average (TWA) sound level of 85 dB Department of Comprehensive Medicine): Hearing measured on the A scale (dBA). This ruling meant that loss is becoming an increasingly important health unless engineering or administrative controls were ef­ hazard of concern to family physicians because of the fective, employees would be prohibited from working relative increased intensity and duration of worker ex­ without protective hearing devices such as earmuffs or posure to noises associated with industrial societies. earplugs. The concept of the time-weighted average Although hearing loss can occur from a variety of in­ implies that louder noises could be tolerated for sults, the noise-induced hearing loss is the matter of shorter exposure times. A scale was developed to current concern. guide directors of hearing conservation programs to help control the dose of noise exposure (Table 1). From the Department of Comprehensive Medicine, College of Medicine, Workers can tolerate up to 80 dBA for 8 hours a day University of South Florida, Tampa, Florida. Requests for reprints should be addressed to Dr. Tom Gladfelter, Department of Family Practice, The without developing hearing impairment, but when the University of Illinois, One III ini Drive, Box 1649, Peoria, IL 61656. level of 85 dBA or more is exceeded, increasing num-

® 1986 Appleton-Century-Crofts the JOURNAL OF FAMILY PRACTICE, VOL. 22, NO. 5: 407-414, 1986 407 NOISE-INDUCED HEARING LOSS

TABLE 1. EQUIVALENT NOISE EXPOSURE OF cal consultations because of severe or profound hear­ DIFFERENT SOUND LEVELS AND THEIR DURATIONS ing loss. Twelve were advised to have a recheck in six months and 11 were considered normal. That means Sound Level Duration about 65 percent of workers had abnormal test results (dBA) in Hours or results that suggested hearing loss. None of the workers had complained about hearing loss. It is dif­ 90 8 ficult to say what the university’s liability is because 92 6 95 4 no pre-employment physical examinations were con­ 97 3 ducted that included a baseline audiogram for later 100 2 comparison. The university is likely to be held re­ 102 V / 2 sponsible in two ways: as causing the loss, or as ag­ 105 1 110 1/2 gravating a preexisting condition. A private physi­ 115 1/4 o r less cian’s audiogram record would be helpful to explain what had occurred. The value of work-place exposure records of noise levels is obvious to protect the em­ bers of workers will suffer hearing loss. ployer and the employee’s interests. If the exposure The law specified that if the sound level cannot be records indicate high ambient noise levels, the univer­ reduced below the 85-dBA level by engineering con­ sity will have difficulty avoiding responsibility, espe­ trols, the employers must monitor the environmental cially if it cannot prove that hearing loss existed before noise level and keep measurements for the record. To this employment. protect the hearing of workers, employers must meas­ This issue introduces the role of the family physi­ ure workers’ baseline hearing acuity with pure tone cian. In performing a preplacement or pre­ audiogram against which subsequent audiograms can employment physical examination or in presenting be compared. Hearing protectors must be provided ourselves as protectors of patients’ health, it is impor­ and workers must be trained in their use. The tant that we have good baseline information. A routine audiogram should be repeated annually and the re­ physical examination seldom includes a pure tone cords kept permanently. Employers must keep em­ audiogram. Hearing function is usually assessed by ployee work-place noise-exposure records from ob­ striking a tuning fork, whispering words to the patient, tained sound level measurements for two years. If a or holding a wristwatch to the ear to assess grossly worker demonstrates a hearing loss when monitored hearing acuity. This type of screening does not give a audiometrically, it indicates that the current conserva­ reliable or valid test. A valid audiogram is the only tion program is not effective and additional measures record that will stand up in court. If the audiometer need to be taken to prevent further loss of function. test results are on the record, then the physician can It is now required that the baseline audiogram be serve to protect the interests of the patient. conducted within six months of an employee’s first To sum up, work-related hearing loss is a common exposure at or above the 85-dBA level. Pure tone problem in American society. With the new regulation, audiometry should be performed at 500-, 1,000-, family physicians can no longer superficially examine 2,000-, 3,000-, 4,000-, and 6,000-Hz testing frequencies the hearing function in the routine physical examina­ by a licensed or certified audiologist, otolaryngologist, tion. They must obtain audiograms as part of their qualified physician, or by a technician who is certified office medical examinations to protect the interests of by the Council of Accreditation on Occupational Hear­ their patients and to continue providing quality com­ ing Conservation. It is important to remember before prehensive care. testing that the employee not be exposed to loud noise RESIDENT PHYSICIAN: What audiogram ma­ for at least 14 hours before the baseline audiogram is chines are accessible for use in the office setting? taken. This precaution is required to reduce the chance DR. ALEXIOU: There are a variety of portable of recording a “temporary threshold shift” of the hear­ units that can be used for screening purposes. The cost ing acuity commonly seen after noise exposure. of the machine is minimal, about $200 to $300. Ideally a baseline audiogram should be conducted for RESIDENT PHYSICIAN: Are those reliable as all employees prior to their employment, but the regu­ screening devices? lation allows the test to be performed as late as six DR. ALEXIOU: Definitely! But remember, as months after employment. One can see a possible mentioned earlier, a test is valid only when it is done problem arising from this policy if high-frequency on patients who have been free from noise exposure hearing loss is identified six months after a person has for at least 14 hours, when it is administered by qual­ been working in a noisy environment. ified personnel on calibrated equipment, and when it I would like to share with you the experience in our takes place in a controlled environment. A soundproof own university screening program. Thirty-one univer­ booth is required for diagnostic purposes, but not for a sity physical plant employees were given baseline screening procedure. If findings suggest something ab­ audiograms for the first time in the early part of 1983. normal using this type of inexpensive testing, it would The results indicated that eight needed otolaryngologi- be appropriate to refer the patient to an otolaryn-

408 THE JOURNAL OF FAMILY PRACTICE, VOL. 22, NO. 5, 1986 NOISE-INDUCED HEARING LOSS gologist or audiologist for further workup. Referral in sounds muffled after work are important indicators of this case would mean suspecting a hearing loss of more possible noise-induced hearing loss.8 Patients often than 25 decibels at 500, 1,000, or 2,000 Hz or other may not verbalize or volunteer such symptoms during unusual irregularity.6 physical examination, yet these are the symptoms we RESIDENT PHYSICIAN: How do we know need to identify for an audiogram. Remember, how­ whether there has been a significant change after a ever, that when these symptoms are present, perma­ person has been working for some time and whether nent damage may have already occurred. this is work related? Next, let me introduce Dr. Saraceno, an otolaryn­ DR. ALEXIOU: A significant change is demon­ gologist, who will discuss the clinical evaluation of strated by a change in hearing threshold relative to the hearing loss. baseline audiogram of an average of 10 dB or more at DR. CARMELO SARCENO (Associate Professor, 2,000-, 3,000-, and 4,000-Hz frequencies in either ear, Department of Otolaryngology)'. What Dr. Alexiou has or a 20-dB or more reduction at any frequency. There been talking about is becoming increasingly important is an expected annual decrement of hearing acuity that in industrialized society; we can expect patients com­ is age related, which must be considered in evaluating ing to us with chief complaints of hearing loss. Now a significant change in hearing acuity.5,7 By the age of how do we evaluate the complaint and identify those 60 years in man, there is about 10-dB average loss in patients with NIHL? hearing acuity in speech frequencies. I will limit my efforts to NIHL, presbycusis, RESIDENT PHYSICIAN: If there is a change from otosclerosis, and drug-induced hearing loss in the fol­ the pre-employment and the follow-up audiogram, lowing discussion. Patients with these disorders are does the company check the lifestyle of the employee often adults with few or no symptoms, their otoscopic to see whether there are other factors causing the hear­ examinations are often normal, and their disorder can ing loss? be hard to differentiate by history and physical exam­ DR. ALEXIOU: No, this is generally not done. The ination alone. hearing loss is presumed to be work related, particu­ With the exception of otosclerosis, these disorders larly if records document that the employee had been are due to sensorineural hearing loss with the pathol­ working in a 80- to 90-dBA environment or above. In ogy found in the inner ear—the cochlea and acoustic such a case the company is liable, and the potential nerve, where the sound energy is encoded into nerv­ monetary award can be significant. Prevention is the ous impulses. If you question patients closely, sen­ real goal. An effective noise control program does not sorineural hearing loss usually presents with the symp­ have to be expensive, but it should reduce noise levels toms mentioned earlier by Dr. Gladfelter. Patients to a TWA of 85 dBA or less. An inexpensive set of have difficulty in understanding when in crowded and earplugs can attenuate noise levels that could cause noisy rooms, and there may be tinnitus. Both symp­ damage, would cost about 50, and could be worn all toms are common in sensorineural hearing loss. In day. Remember, the preferred additional control contrast, otosclerosis is a conductive hearing loss, measures are (1) engineering controls to reduce the often found in young to middle-aged women. The pa­ origin of the noise, (2) employee education programs thology presents in the middle ear with sclerotic to improve the awareness of employees of the need to changes in the ossicles leading to a reduction of sound wear protective devices, and (3) enforcement, which is energy transmission to the inner ear. These patients the proper administration of the hearing protection can experience tinnitus, but they often have a lesser program by supervisors. These are the three E’s to problem of hearing conversation in a crowded room; in remember. fact, they may hear better, a phenomenon known as DR. GLADFELTER: From the viewpoint of the “paracusia willisiana.” 9 It serves as a good indicator family physician who conducts periodic or pre­ of otosclerosis or other conductive hearing losses. employment physical examinations, the inclusion of an Vertigo is another important symptom to look for, as audiogram means additional cost for trained person­ it is one of the first presenting symptoms of inner-ear nel, equipment, a quiet room or a soundproof booth, pathology. The labyrinth is part of the inner ear. Any and the time required to conduct the test. The cost etiological factor involving the cochlea will likely in­ effectiveness of providing testing depends on the volve the labyrinth, and the patient will suffer from sound level exposure experienced by the patient. vertigo. Meniere’s disease is a good example, with its Audiograms are not routinely necessary for people characteristic triad of vertigo, hearing loss, and tin­ working all day in a quiet office, but these baseline nitus.10 Vertigo and high-pitched tinnitus are early data are definitely needed for people who are going to signs of acoustic neuroma. Both are also frequently work in noisy places, such as factories and construc­ present with ototoxicity resulting from medicine or tion sites. An inquiry into the occupational history will drugs. Seldom found in patients with NIHL and identify people at risk. It is also important to ask about presbycusis, vertigo is important in discriminating a history of other symptoms often associated with Meniere’s disease and ototoxicity of drugs from the noise trauma. Difficulty in hearing conversation in other causes of sensorineural hearing loss. noisy places, transient tinnitus, or speech or other Continued on page 412

THE JOURNAL OF FAMILY PRACTICE, VOL. 22, NO. 5, 1986 409 SINEQUAN (doxepn HCI) NOISE-INDUCED HEARING LOSS BRIEF SUMMARY SINEQUAN" (doxepin HCI) Capsules/Oral Concentrate Contraindications. SINEQUAN is contraindicated in individuals who have shown hyper­ Continued from page 409 sensitivity to the drug. Possibility of cross sensitivity with other dibenzoxepines should be kept in mind. FREQUENCY IN HERTZ SINEQUAN is contraindicated in patients with glaucoma or a tendency to urinary retention. These disorders should be ruled out, particularly in older patients. W arnings. The once-a-day dosage regimen of SINEQUAN in patients with intercurrent KEY Right Left illness or patients taking other medications should be carefully adjusted. This is especially important in patients receiving other medications with anticholinergic effects. A ir OX Usage in Geriatrics: The use of SINEQUAN on a once-a-day dosage regimen in geriatric patients should be adjusted carefully based on the patient’s condition. Bone z 2 Usage in Pregnancy: Reproduction studies have been performed in rats, rabbits, color Red Blue monkeys and dogs and there was no evidence of harm to the animal fetus. The relevance to Lim its of humans is not known. Since there is no experience in pregnant women who have received this Audiometer i drug, safety in pregnancy has not been established. There are no data with respect to the secretion of the drug in human milk and its effect on the nursing infant. Usage in Children: The use of SINEQUAN in children under 12 years of age is not recommended because safe conditions for its use have not been established. MAO Inhibitors: Serious side effects and even death have been reported following the concomitant use of certain drugs with MAO inhibitors. Therefore, MAO inhibitors should be discontinued at least two weeks prior to the cautious initiation of therapy with SINEQUAN. Vertigo ■ru O The exact length of time may vary and is dependent upon the particular MAO inhibitor being used, the length of time it has been administered, and the dosage involved. Tinnitus h V Usage with Alcohol: It should be borne in mind that alcohol ingestion may increase the Recrui tment 14 C danger inherent in any intentional or unintentional SINEQUAN overdosage. This is especially important in patients who may use alcohol excessively. Paracusis h , 0 Precautions. Since drowsiness may occur with the use of this drug, patients should be warned of the possibility and cautioned against driving a car or operating dangerous machin­ ery while taking the drug. Patients should also be cautioned that their response to alcohol may Figure 1. An actual audiogram of a 55-year-old asymp­ be potentiated. tomatic man who served as a machinist’s mate in the Since suicide is an inherent risk in any depressed patient and may remain so until significant improvement has occurred, patients should be closely supervised during the early Navy for 20 years course of therapy. Prescriptions should be written for the smallest feasible amount. Should increased symptoms of psychosis or shift to manic symptomatology occur, it may be necessary to reduce dosage or add a major tranquilizer to the dosage regimen. Adverse Reactions. NOTE: Some of the adverse reactions noted below have not been specifically reported with SINEQUAN use. However, due to the close pharmacological I will mention briefly making a diagnosis based on similarities among the tricyclics, the reactions should be considered when prescribing SINEQUAN. otoscopic examination. In general, all patients with Anticholinergic Effects: Dry mouth, blurred vision, constipation, and urinary retention have been reported. If they do not subside with continued therapy, or become severe, it may be sensorineural hearing losses, including NIHL, have necessary to reduce the dosage. normal-appearing eardrums.11 The same is true for Central Nervous System Effects: Drowsiness is the most commonly noticed side effect. This tends to disappear as therapy is continued. Other infrequently reported CNS side effects otosclerosis, but occasionally by careful inspection it are confusion, disorientation, hallucinations, numbness, paresthesias, ataxia, and extra- pyramidal symptoms and seizures. is possible to detect a few cases of otosclerosis by Cardiovascular: Cardiovascular effects including hypotension and tachycardia have been reported occasionally. looking at the incus through the semitransparent tym­ Allergic: Skin rash, edema, photosensitization, and pruritus have occasionally occurred. Hematologic: Eosinophilia has been reported in a few patients. There have been occa­ panic membrane for a faint pink blush representing the sional reports of bone marrow depression manifesting as agranulocytosis, leukopenia, increased vascularity in the otosclerotic bone thrombocytopenia, and purpura. Gastrointestinal: Nausea, vomiting, indigestion, taste disturbances, diarrhea, anorexia, (Schwartze’s sign). The tuning fork is used in the phys­ and aphthous stomatitis have been reported. (See anticholinergic effects.) Endocrine: Raised or lowered libido, testicular swelling, gynecomastia in males, enlarge­ ical examination for the Rinne and the Weber tests. ment of breasts and galactorrhea in the female, raising or lowering of blood sugar levels, and syndrome of inappropriate antidiuretic hormone have been reported with tricyclic These tests help locate the site or identify the type of administration. Other: Dizziness, tinnitus, weight gain, sweating, chills, fatigue, weakness, flushing, jaun­ hearing loss, but as Dr. Alexiou has pointed out, they dice, alopecia, and headache have been occasionally observed as adverse effects. Withdrawal Symptoms: The possibility of development of withdrawal symptoms upon should not be used to detect the degree of hearing loss. abrupt cessation of treatment after prolonged SINEQUAN administration should be borne in With a pure tone audiogram, the degree of hearing mind. These are not indicative of addiction and gradual withdrawal of medication should not cause these symptoms. loss can be quantitated for the various frequencies of Dosage and Administration. For most patients with illness of mild to moderate severity, a starting daily dose of 75 mg is recommended. Dosage may subsequently be increased or sound. In otosclerosis, the hearing loss occurs in all decreased at appropriate intervals and according to individual response. The usual optimum dose range is 75 mg/day to 150 mg/day. frequencies when the sound stimulus is presented by In more severely ill patients higher doses may be required with subsequent gradual increase to 300 mg/day if necessary. Additional therapeutic effect is rarely to be obtained by the air. When the sound stimulus is presented to the exceeding a dose of 300 mg/day. In patients with very mild symptomatology or emotional symptoms accompanying organic bony surface of the patient, the hearing is improved, disease, lower doses may suffice. Some of these patients have been controlled on doses as which explains the so-called air-bone gap seen in con­ low as 25-50 mg/day. The total daily dosage of SINEQUAN may be given on a divided or once-a-day dosage ductive hearing loss. In sensorineural hearing loss, schedule. If the once-a-day schedule is employed the maximum recommended dose is 150 mg/day. This dose may be given at bedtime. The 150 mg capsule strength is hearing by air and bone conduction are about equal. intended for maintenance therapy only and is not recommended for initiation of treatm ent. So how do we differentiate accurately the hearing Anti-anxiety effect is apparent before the antidepressant effect. Optimal antidepressant effect may not be evident for two to three weeks. loss of NIHL from that of presbycusis or ototoxicity of Overdosage. A. Signs and Symptoms drugs? This audiogram shows what you should look 1. Mild: Drowsiness, stupor, blurred vision, excessive dryness of mouth. for in the case of NIHL (Figure 1). Notice a dip at the 2. Severe: Respiratory depression, hypotension, coma, convulsions, cardiac arrhythmias and tachycardias. 4.000- Hz frequency while the speech frequencies (500 Also: urinary retention (bladder atony), decreased gastrointestinal motility (paralytic ileus), hyperthermia (or hypothermia), hypertension, dilated pupils, hyperactive reflexes. to 2,000 Hz) are normal. The predominant loss of hear­ B. Management and Treatment 1. Mild: Observation and supportive therapy is all that is usually necessary. ing acuity around 4,000 Hz with preservation of 8,000 2. Severe: Medical management of severe SINEQUAN overdosage consists of aggressive supportive therapy. If the patient is conscious, gastric lavage, with appropriate precautions to Hz is typical of NIHL. Later on in the process of prevent pulmonary aspiration, should be performed even though SINEQUAN is rapidly absorbed. The use of activated charcoal has been recommended, as has been continuous disease, when the hearing loss becomes progressively gastric lavage with saline for 24 hours or more. An adequate airway should be established in worse, the 4,000-Hz loss will become more pro­ comatose patients and assisted ventilation used if necessary. EKG monitoring may be required for several days, since relapse after apparent recovery has been reported. Ar­ nounced and the lower speech frequencies and higher rhythmias should be treated with the appropriate antiarrhythmic agent. It has been reported that many of the cardiovascular and CNS symptoms of tricyclic antidepressant poisoning in 8.000- Hz frequencies will also become affected.12 In adults may be reversed by the slow intravenous administration of 1 mg to 3 mg of physostig- mine salicylate. Because physostigmine is rapidly metabolized, the dosage should be presbycusis, the pattern is an increased hearing loss in repeated as required. Convulsions may respond to standard anticonvulsant therapy, however, barbiturates may potentiate any respiratory depression. Dialysis and forced diuresis gener­ the higher frequencies, with a greater loss in 8,000-Hz ally are not of value in the management of overdosage due to high tissue and protein binding of SINEQUAN. than in 4,000-Hz range. If you see this pattern, then the More detailed professional information available on request. presumptive diagnosis is presbycusis. To complicate the diagnosis, the audiometric finding of hearing loss ROeRIG A division of Pfizer Pharmaceuticals THE JOURNAL OF FAMILY PRACTICE, VOL. 22, NO. 5, 1986 New York, New York 10017 noise-in d u c e d h e a r in g loss due to ototoxicity of drugs is similar to that of the normal aging process. Aggressive therapy for a presbycusis. In such cases, we have to rely heavily on concurrent medical problem should at least prevent the medication history to make the differential diag­ further deterioration of the hearing function.1617 This nosis. The drugs known to cause hearing loss include applies to the treatment of presbycusis as well. aminoglycoside antibiotics, furosemide, and salicy­ For the patient with a disabling hearing loss, a hear­ lates, all of which are familiar to us.1314 Fortunately, in ing aid will sometimes provide relief. A patient with a most circumstances hearing loss that is due to drugs is high-frequency loss that has a mild effect on speech reversible. It allows us a chance to withdraw the drug. frequencies can be helped by a high-frequency gain A repeat audiogram should demonstrate improvement aid.1K However, if the patient has severe impairment in with drug withdrawal. In NIHL and presbycusis, how­ discriminating between words with close phonation, ever, the loss is permanent, and there is no change in the likelihood of benefit from a hearing aid is greatly the audiogram with repeated examinations. reduced. Tinnitus, which always accompanies mild to The patient with a history of military service, work­ severe NIHL, can be sometimes treated by “tinnitus ing with noisy machinery, attending musical gather­ maskers.” In this instance a less annoying noise is ings, especially to hear modern rock-and-roll music, or introduced to mask the presence of the tinnitus. other occupational historical events that exposed him As a final reminder, when you have a patient with or her to high noise level may have developed hearing hearing loss, it is very important to sit down with the difficulty insidiously over the years. If the physical family members and explain what it means to not be able examination shows normal eardrums, and the audio- to hear. Frequently the family will believe the patient gram has the typical dip at 4,000 Hz in both ears with­ hears only what he wants to hear or may not hear when out air-bone gap, then you can generally make a fairly something is inconvenient. It is important for the phy­ accurate diagnosis of NIHL. But you should raise sician to tell the family that the audiometric test shows questions if the hearing loss is unilateral. Since noise the patient has impaired hearing and the family should affects both ears, the impairment is always bilateral be understanding and supportive. Sometimes patient except in certain circumstances when each ear is ex­ and family can be helped to understand each other by posed to different noise levels; firing a rifle is a good attending speech reading courses for persons with dif­ example. Once asymmetry is significant, other causes ferent types of disorders in communications. of hearing loss need to be evaluated. A dispropor­ RESIDENT PHYSICIAN: What level of street tionately impaired ability to understand speech is usu­ noise can result in damage to hearing? ally diagnostic of an acoustic nerve pathology rather DR. ALEXIOU: Eighty decibels and above can re­ than cochlear pathology.13 sult in hearing damage. There is individual variation, Audiometric testing requires thorough cooperation and sensitive individuals may be susceptible to damage from the patients. When the patient is not cooperative, at 80 decibels, but most of the population will be tympanometry, which simply measures the middle-ear protected if they experience less than 85 decibels of pressure and gives an indication of presence of sound level pressure.16 For reference purposes, noise middle-ear pathology,11 such as fluid accumulation and measurement in a quiet room will be about 40 dB, otosclerosis, can be used. One part of tympanometry conversation at 3 feet will measure 60 dB, a home vac­ is the acoustic reflex, which tells whether the sensory uum cleaner will measure 70 dB, a garbage disposal neural level is grossly abnormal. This acoustic reflex unit at 3 feet will measure 80 dB, a power lawn mower measures the stapedius muscle contraction in the non­ will measure at the operator’s ear 100 dB, and a power test ear when a loud sound is delivered to the ear being saw will measure 110 dB. tested. If a reflex is recorded, the ear is obviously not DR. SARACENO: Generally speaking, the shorter totally deaf and the entire neural pathway is probably the exposure, the louder the noise has to be to cause intact. The last diagnostic test I will mention is called temporary or permanent hearing loss. Continuous ex­ auditory brain-stem response audiometry. It is similar posure to noise is worse than intermittent exposure. to electroencephalography except that it tracks the Middle- or high-frequency noises are more harmful brain-stem response to auditory stimuli.11,15 It is espe­ than low-frequency noise. cially valuable for people who complain about hearing RESIDENT PHYSICIAN: Have you seen hearing loss and their audiometric test is not entirely normal or loss caused by loud music played on a portable stereo when legal matters are involved. with earphones? Otosclerosis is amenable to treatment by surgical DR. SARACENO: I have not seen that yet, but I procedures. There is no good treatment for sen­ suspect I may see a few patients in the future. A recent sorineural hearing loss. The only good treatment for Federal Drug Administration bulletin warned about NIHL is prevention by protection of the worker and the use of the cordless telephone, which when placed altering the environment to eliminate the unwanted over the ear while it is still ringing can give up to noise. It is very important, especially for the family 135 dB of noise and cause severe damage.20 physician, to treat any concurrent medical problem DR. GLADFELTER: This has been a productive such as hypertension and diabetes mellitus, and not presentation and discussion. I would like to sum this take for granted that the hearing loss is associated with up by urging family physicians to (1) take an occupa-

THE JOURNAL OF FAMILY PRACTICE, VOL. 22, NO. 5, 1986 413 NOISE-INDUCED HEARING LOSS

tional history, (2) selectively use the audiometer for pre-employment physical examinations for high-risk workers, (3) educate your patients to wear protective ISOPTIN devices such as earmuffs or plugs, and (4) participate (verapamil HCI/Knoll) actively as consultant to the employer to help set up 80 mg and 120 mg scored,film-coated tablets hearing conservation programs that comply with the safety regulations to reduce the possibility of litigation Contraindications: Severe left ventricular dysfunction (see Warnings), hypo­ tension (systolic pressure < 90 mm Hg) or cardiogenic shock, sick sinus syn­ and the number of worker compensation claims. We drome (except in patients with a functioning artificial ventricular pacemaker), also have the role of coordinators of all medical disci­ 2nd- or 3rd-degree AV block. Warnings: ISOPTIN should be avoided in patients with severe left ventricular dysfunction (e.g., ejection fraction < 30% or plines to provide the best service to our patients, moderate to severe symptoms of cardiac failure) and in patients with any should the need arise. degree of ventricular dysfunction if they are receiving a beta blocker. (See Precautions.) Patients with milder ventricular dysfunction should, if possible, be controlled with optimum doses of digitalis and/or diuretics before ISOPTIN is used. (Note interactions with digoxin under Precautions.) ISOPTIN may occa­ References sionally produce hypotension (usually asymptomatic, orthostatic, mild and con­ trolled by decrease in ISOPTIN dose). Elevations of transaminases with and 1. Myers D, Schlosser WD, Wolfson JR, et al: Otologic diag­ w ithout concomitant elevations in alkaline phosphatase and bilirubin have been reported. Such elevations may disappear even w ith continued treatment; how­ nosis and the treatment of deafness. Clin Symp 1970' ever, four cases of hepatocellular injury by verapamil have been proven by re­ 22(2):37-43 challenge. Periodic monitoring of liver function is prudent during verapamil 2. Erlandsson B, Hakanson H, Ivarsson A, et al: Hair cell dam­ therapy. Patients with atrial flutter or fibrillation and an accessory AV pathway age in guinea pig due to different kinds of noise. Acta (e.g. W-P-W or L-G-L syndromes) may develop increased antegrade conduction Otolaryngol (suppl) 1980; 367:1-43 across the aberrant pathway bypassing the AV node, producing a very rapid ventricular response after receiving ISOPTIN (or digitalis). Treatment is usually 3. Melnick W: Noise and hearing loss. In Keith RW (ed): D.C.-cardioversion, which has been used safely and effectively after ISOPTIN Audiology for the Physician. Baltimore, Williams & Wilkins, Because of verapamil's effect on AV conduction and the SA node, 1° AV block 1980, pp 213-237 and transient bradycardia may occur. High grade block, however, has been 4. Department of Labor, Occupational Safety and Health Ad­ infrequently observed. Marked 1° or progressive 2° or 3° AV block requires a dosage reduction or, rarely, discontinuation and institution of appropriate ministration: Part III. Occupational noise exposure, hearing therapy depending upon the clinical situation. Patients with hypertrophic car­ conservation amendment. Federal Register 1981 diomyopathy (IHSS) received verapamil in doses up to 720 mg/day. It must be 46(11 ):4112 appreciated that this group of patients had a serious disease with a high mor­ 5. Occupational noise exposure, hearing conservation tality rate and that most were refractory or intolerant to propranolol. A variety of serious adverse effects were seen in this group of patients including sinus amendment, final rule. Federal Register 1983; 48(46)9738- bradycardia, 2° AV block, sinus arrest, pulmonary edema and/or severe hypo­ 9785 tension. Most adverse effects responded well to dose reduction and only rarely 6. Fox MS: Industrial noise exposure and hearing loss. In Bal- was verapamil discontinued. Precautions: ISOPTIN should be given cautiously lenger JJ (ed): Disease of The Nose, Throat, and Ear, ed 12. to patients with impaired hepatic function (in severe dysfunction use about 30% of the normal dose) or impaired renal function, and patients should be Philadelphia, Lee & Febiger, 1977, pp 984-986 monitored fo- abnormal prolongation of the PR interval or other signs of exces­ 7. Glorig A: Compensation for industrial hearing loss: The sive pharmacologic effects. Studies in a small number of patients suggest that practice in the United States. In Beagley HA (ed): Audiology concomitant use of ISOPTIN and beta blockers may be beneficial in patients and Audiological Medicine. Oxford, Oxford University Press, with chronic stable angina. Combined therapy can also have adverse effects on 1981, pp 861-879 cardiac function. Therefore, until further studies are completed, ISOPTIN should be used alone, if possible. If combined therapy is used, close surveillance of vital 8. Guide for Conservation of Hearing in Noise. Rochester, signs and clinical status should be carried out. Combined therapy with ISOPTIN Minn, American Academy of Ophthalmology and Otolaryn­ and propranolol should usually be avoided in patients w ith AV conduction gology, 1973 abnormalities and/or depressed left ventricular function. Chronic ISOPTIN treat­ 9. Ballenger JJ: Otosclerosis. In Disease of The Nose, Throat, ment increases serum digoxin levels by 50% to 70% during the first week of therapy, which can result in digitalis toxicity. The digoxin dose should be re­ and Ear, ed 12. Philadelphia, Lea & Febiger, 1977, pp 885- duced when ISOPTIN is given, and the patients should be carefully monitored to 891 avoid over- or under-digitalization. ISOPTIN may have an additive effect on 10. Dickins JRE, Graham SS: Meniere’s disease 1978-1982. Am lowering blood pressure in patients receiving oral antihypertensive agents. J Otolaryngol 1984; 5(2):137-155 Disopyramide should not be given within 48 hours before or 24 hours after ISOPTIN administration. Until further data are obtained, combined ISOPTIN and 11. DeWeese DD, Saunders WH: Evaluation of hearing. In quinidine therapy in patients with hypertrophic cardiomyopathy should prob­ Textbook of Otolaryngology, ed 6. St. Louis, CV Mosby ably be avoided, since significant hypotension may result. Clinical experience 1982, pp 279-295 with the concomitant use of ISOPTIN and short- and long-acting nitrates sug­ 12. Ruth RA: Audiometric evaluation of noise induced hearing gest beneficial interaction w ithout undesirable drug interactions. Adequate ani­ loss. Otolaryngol Clin North Am 1979; 12(3):639-654 mal carcinogenicity studies have not been performed. One study in rats did not suggest a tumorigenic potential, and verapamil was not mutagenic in the Ames 13. DeWeese DD, Saunders WH: Hearing loss. In Textbook of test. Pregnancy Category C: There are no adequate and well-controlled studies Otolaryngology, ed 6. St. Louis, CV Mosby, 1982, pp 347-373 in pregnant women. This drug should be used during pregnancy, labor and 14. Fausti SA, Rappaport BZ, Schechter MA, et al: Detection of delivery only if clearly needed. It is not known whether verapamil is excreted in aminoglycoside ototoxicity by high-frequency auditory breast milk; therefore, nursing should be discontinued during ISOPTIN use. Adverse Reactions: Hypotension (2.9%), peripheral edema (1.7%), AV block: evaluation, selected case studies. Am J Otolaryngol 1984; 3rd degree (0.8% ), bradycardia: HR < 50/min (1.1%), CHF or pulmonary 5(3): 177-182 edema (0.9%), dizziness (3.6%), headache (1.8%), fatigue (1.1%), constipa 15. Gibroux AP, Pratt LW: Brain stem evoked response tion (6.3%), nausea (1.6%), elevations of liver enzymes have been reported. audiometry. Ann Otol Rhinol Laryngol 1983; 92:183-186 (See Warnings.) The following reactions, reported in less than 0.5%, occurred under circumstances where a causal relationship is not certain: ecchymosis, 16. Rosen S, Plester D, El-Mofty A, et al: Relation of hearing loss bruising, gynecomastia, psychotic symptoms, confusion, paresthesia, insomnia, to cardiovascular disease. Trans Am Acad Ophthalmol somnolence, equilibrium disorder, blurred vision, syncope, muscle cramp, shaki- Otolaryngol 1964; 68:433-444 ness, claudication, hair loss, macules, spotty menstruation How Supplied: 17. Axelsson A, Sigroth K, Vertes D: Hearing in Diabetics. Acta ISOPTIN (verapamil HCI) is supplied in round, scored, film-coated tablets con­ taining either 80 mg or 120 mg of verapamil hydrochloride and embossed with Otolaryngol (suppl) 1978; 356:1-23 "ISOPTIN 80" or "ISOPTIN 120" on one side and with "KNOLL" on the reverse 18. Sinclair JC: Design and performance of hearing aids. In side. Revised August, 1984. 2385 Bradford LJ, Hardy WG (eds): Hearing and Hearing Impair­ ment. New York, Grune & Stratton, 1979, pp 173-192 19. Ward WD: The concept of susceptibility to hearing loss. J S -J KNOLL PHARMACEUTICAL COMPANY Occup Med 1965; 7:595-607 K n o ll 30 NORTH JEFFERSON ROAD, WHIPPANY, NEW JERSEY 07981 20. Hearing loss with cordless phones. FDA Drug Bull 1984; 14(3) :26 2406

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