The audiologist's primary roles in healthcare include the identification of hearing loss, habilitation or rehabilitation, and hearing conservation. However, audiologists also function as gatekeepers to medical care. Appropriate medical referrals can, for some patients, reduce the risk of worsening hearing and other medical complications. It is therefore recommended that audiologists adopt clinic referral guidelines.
This article contains guidelines for audiology that can be adopted as written or after editing. The guidelines can also be adapted for use in non-audiology clinics, including those of board-certified hearing instrument specialists.
This article is divided into three sections. Section 1 contains guidelines for medical clearance for hearing aid use. Section 2 presents criteria for identifying candidates for magnetic resonance imaging (MRI) to rule out vestibular schwannomas. Successful use of Section 2 criteria requires that each clinic find an otolaryngologist who agrees with the criteria and will order MRIs accordingly. Section 3 contains referral criteria for type B tympanograms.
Also included are two flow charts, one to guide decision making regarding case history and one to guide decision making regarding audiometric findings.
Criteria for identifying patients in need of medical clearance
The Food and Drug Administration (FDA) hearing aid fitting referral criteria, established in 1977, will serve as the audiology clinic's minimum guideline for determining the need for medical clearance for hearing aid use.1 An exception is cerumen impaction, since cerumen management is within audiology's scope of practice in this state (Florida)—and many others states as well. Patients with impacted cerumen may, at the discretion of the examining audiologist, be managed in the audiology clinic.
The FDA criteria for referral to a physician are:
1. Visible congenital or traumatic deformity of the ear.
2. History of active drainage from the ear within the previous 90 days.
3. History of sudden or rapidly progressing hearing loss within the previous 90 days.
4. Acute or chronic dizziness.
5. Unilateral hearing loss of sudden or recent onset within the previous 90 days.
6. Audiometric air-bone gap equal to or greater than 15 dB at 500 Hz, 1000 Hz, and 2000 Hz.
7. Visible evidence of significant cerumen accumulation or a foreign body in the ear canal.
8. Pain or discomfort in the ear.
9. Child under 18 years of age.
In 1993 and 1994, the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) published criteria for when referral to a physician is called for.2,3 While some of these recommendations are identical to FDA's, the following criteria are different from the federal agency's and would lead to more patients being referred:
* History of active drainage from the ear within the previous 6 months.
* History of sudden or rapidly progressing hearing loss within the previous 6 months.
* Clarification of the FDA rule on unilateral or asymmetric hearing loss: Unilateral or asymmetric hearing loss defined as an air-conduction pure-tone PTA (500, 1000, 2000, and 3000 Hz) difference of 15 dB or greater.
* Sudden or recent onset within the previous 6 months.
* Bilateral hearing loss greater than 90 dB.
* Complaint of hearing impairment with positive history of: tuberculosis, syphilis, HIV, Meniere's disease, auto-immune disorder, otosclerosis, Von Recklinghausen's neurofibromatosis, or Paget's disease of the bone.
Audiologic decision making
When a patient meets any of the FDA criteria (except cerumen impaction), it indicates the need for medical evaluation prior to a hearing aid fitting. Patients who meet one or more of AAO's criteria will be considered for referral at the discretion of the examining audiologist.
Criteria for identifying candidates for MRI to rule out vestibular schwannomas
Vestibular schwannomas (acou-stic neuromas) most often occur unilaterally, and therefore cause unilateral or asymmetric symptoms and findings. Patients will be referred to an otolaryngologist for consideration for magnetic resonance imaging (MRI) if they have the following three unilateral or asymmetric findings:
1. Asymmetric pure-tone air-conduction sensorineural thresholds.
a. Asymmetric SNHL of 25 dB or more at any two consecutive test frequencies (National Hearing Conservation Associ-ation referral criteria4).
b. Unilateral or asymmetric hearing impairment. AAO-HNS criteria: average differ-ence in air-conduction thresh-olds between ears of 15 dB or greater at 500 Hz, 1000 Hz, 2000 Hz, and 3000 Hz.
2. Asymmetric word-recognition scores.
3. Statistically significant differ-ence in word-recognition scores (WRS) between ears using Thornton and Raffin's data5 and NU#6 word lists.
4. Persistent unilateral or asymmet-ric tinnitus.
Audiologic details and decision making
Audiologists will consider the Welling decision tree in deciding whether or not patients need to be referred to an otolaryngologist with consideration for MRI.6 The decision tree contains three branches, one for patients with a high probability (p>30%) of having a vestibular schwannoma, one for patients with an intermediate (5%<p<30%) probability, and one for patients with a low probability (p<5%). These categories are based on the following audiometrics and symptoms:
HISTORY: Unilateral asymmetric sensorineural hearing loss, tinnitus, and decreased discrimination.6
Audiologists will consider the following as guidelines for identifying asymmetry consistent with a high-probability patient. Patients whose findings meet the three following criteria will be candidates for referral to an otolaryngologist for consideration for an MRI.
* Unilateral or asymmetric sensorineural hearing loss (SNHL) not explained by history (Note: A unilateral or asymmetric SNHL is considered to be explained by history if permanent threshold shift, and/or temporary threshold shift, and/or tinnitus occurred in the poorer ear at or near in time to an acoustic or physical trauma, a disease onset or progression, or an otologic treatment).
a. Asymmetric SNHL of 25 dB or more at any two consecutive test frequencies (NHCA referral criteria3).
b. Unilateral or asymmetric hearing impairment (AAO-HNS criteria: average difference in air-conduc-tion thresholds between ears of 15 dB or greater at 500, 1000, 2000, and 3000 Hz.
* Asymmetric word-recognition scores (WRS) not explained by history:
a. Statistically significant difference in WRS between ears using Thornton and Raffin's data5 and NU#6 word lists. The WRS scores analyzed must approximate PB max.
* Unilateral or asymmetric tinnitus not explained by history.
Audiologic decision making
As stated above, anyone whose findings and history meet the three criteria for a high-probability patient will be referred to an otolaryngologist for consideration for an MRI. Auditory evoked potentials (AEP) will also be evaluated in patients presenting with two of the three high-probability criteria. Patients with positive AEP results will be referred to an otolaryngologist for evaluation.
Other patients will be monitored as determined by the examining audiologist. However, even if not all three above criteria are met, the examining audiologist may choose to refer patients if there are other compelling audiologic data (e.g., positive rollover or reflex decay) and/or symptoms (e.g., dizziness, aural fullness, facial paresis, or other symptoms suggestive of cranial nerve pathology).
HISTORY6: Sudden sensorineural hearing loss and otherwise unexplained persistent unilateral tinnitus.
The audiologic criteria used for high-probability patients will also be used for intermediate probability patients.
HISTORY: Isolated vertigo, historically explained unilateral hearing loss, and tinnitus.6
Patients with a low probability of having a vestibular schwannoma will be followed audiologically. Consideration will be given to AEP and other tests, as well as audiologic monitoring. Patients with positive AEP findings, positive findings on other audiologic tests, or worsening symptoms will be considered for referral to an otolaryngologist.
Referral criteria for type B tympanograms and tympanic membrane perforations
In the absence of other referral indicators, flat tympanograms do not necessarily require medical evaluation. However, flat tympanograms could be precursors to otitis media (type B tympanograms) or indicators of a tympanic membrane perforation (tympanograms with high ear canal volume).
* Type B tympanograms: Type B tympanograms are those with static compliance below and/or tympanogram gradient greater than that expected according to published normative data. Patients with type B tympanograms, in the absence of other audiologic referral indicators, will be monitored audiologically, consistent with ASHA recommendations for tympanometric screening.7 These patients will be seen for a repeat tympanogram in 6–8 weeks, but with instructions to seek immediate medical attention if otalgia or other unusual symptom is experienced. Patients with persistent type B tympanograms may be candidates for referral to an otolaryngologist at the discretion of the examining audiologist.
* Tympanic membrane perforations: Flat tympanograms with high ear canal volumes suggest a perforated tympanic membrane. This should be confirmed with otoscopy. Patients with longstanding dry perforations that, according to the history or medical record documentation, have been examined by physicians will not be referred. Instead, they will be in-structed on dry ear precautions and appropriate hearing aid use and be periodically monitored.
In contrast, patients will be referred to an otolaryngologist if they have previously undiagnosed perforations or visible otorrhea from or near the perforation, or if they desire a consultation regarding tympanoplasty.
James R. Steiger, PhD, is an audiologist with the West Palm Beach (FL) Veterans Affairs Medical Center. Correspondence to Dr. Steiger at email@example.com.