Expert Review Examination of the Ear Using the Tuning Fork Tests - PDF Document

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  1. Expert Review Examination of the Ear Using the Tuning Fork Tests Tom GH Bowden* and Martin J Burton# …………………………………………………………………………………………………………………………………….. The Journal of Clinical Exam ination 2007; 2: 4-6 Abstract The tuning fork tests provide a reliable clinical m ethod for assessing the nature of a patient’s hearing loss. They require m inim al equipm ent, and are sim ple to perform . This review provides a routine for perform ing Rinne’s and Weber’s tests. It follows the principles of clinical exam ination [1] and should provide a useful resource for the both novice m edical student and the m ore experienced clinician who m ay be required to perform these tests. Key Words: tuning fork, Rinne, Weber. Address for correspondence: tom .bowden@doctors.org.uk Authors’ Affiliations * Final Year Medical Student, The University of Oxford. # Consultant, Departm ent of Otolaryngology, University of Oxford and John Radcliffe Hospital Oxford, UK. …………………………………………………………………………………………………………………………………….. Introduction The tuning fork tests provide a reliable clinical m ethod for assessing the nature of a patient’s hearing loss. They are m ost useful in patients with unilateral hearing loss which is purely conductive or purely sensorineural. Patients with bilateral loss or m ixed losses are better assessed with form al pure tone audiom etry. These tests should be carried out in a full exam ination of the cranial nerves or the ear. However, as they do not fall neatly into either category we will consider them separately here. The two tests we will consider here are Rinne’s test and Weber’s test. Other tuning fork tests include the Schwabach and Bing tests, though these are not used in routine practice. The Rinne and Weber tests both require a skilled exam iner and a basic understanding of the patho-physiology of hearing and hearing loss. These tests help distinguish between a conductive hearing loss (CHL) and sensorineural Hearing Loss (SHL), and identify a patient with a totally ‘dead’ ear. Examination As for all clinical exam inations, we aim here to follow the Principles of Clinical Exam ination [1]. Equipm ent needed for this test is a 512 Hz [2] tuning fork. Start by introducing yourself to the patient, asking their perm ission to exam ine them and explain what you are going to do. They should be seated in a quiet room for these tests to be perform ed properly. Weber’s Test To perform Weber’s test strike the fork against your knee or elbow. Then place the base of the fork in the m idline, high on the patient’s forehead (Figure 1). It is im portant to steady the patient’s head with your other hand so that reasonably firm pressure can be applied. Then ask the patient if the patient hears the sound and if so, is it louder in one ear or the other, and if so which? If the patient is unclear, you m ay ask if they hear it “everywhere.” Be careful not to ask the question in a leading m anner. In norm al hearing the sound should be heard equally in both ears. In m any patients they report this as being heard “everywhere” or in the m iddle of the head. If the sound lateralises to one ear then you need to work out whether it is due to a sensorineural or a conductive hearing loss. Knowing which ear has the hearing loss m akes this straight forward. Figure 1 Weber’s Test. 4

  2. Interpretation Weber’s test will ‘lateralise’, i.e. m ove to one side, with a relatively sm all am ount of hearing loss (5dB). In cases of unilateral hearing loss, only 70% of patients will report that the sound has lateralised and of these 25% will refer it to the incorrect ear [3]. If a patient has a conductive cause of unilateral deafness, the tuning fork will ‘lateralise’ to the deaf ear. Recall that in unilateral conductive hearing loss the sound will lateralise to the ear with conductive loss. If a patient has a sensorineural cause of the unilateral deafness, the tuning fork will lateralise to the good ear. Recall again that in unilateral sensorineural loss the sound will lateralise to the norm al ear. In bilateral and sym m etrical hearing loss of either type Weber’s test will be norm al. The various outcom es of the different tests are shown below in Table 1. Rinne’s Test This test aim s com pare air conduction with bone conduction. This test is thought to have a high sensitivity (0.84) [4], though this varies with the skill of the exam iner [5]. This variability m ay be due to the fact that it is an exam ination m anoeuvre and a subjective rather than an objective test of hearing function. Rinne’s test can only detect a conductive hearing loss of at least 30dB [6]. Begin by striking the tuning fork against your knee or elbow. Hold the tuning fork in one hand and place the base against the patient’s m astoid process (Figure 2). Allow it to stay there for 2-3 seconds to allow them to appreciate the intensity of the sound. Then prom ptly lift the fork off the m astoid process and place the vibrating tips about 1cm from their external auditory m eatus (Figure 3). Leave it there again for a few seconds before taking the tuning fork away from their ear. Then ask the patient in which of the positions they were able to hear the note the loudest. A patient who hears the fork loudest when it is held against the m astoid process has a negative Rinne’s test. One who hears it loudest when held 1cm from the external auditory m eatus has a positive Rinne’s test. Results of Rinne’s Test. In a norm al ear sound is conducted to the cochlear m ost efficiently via air conduction. Sound can also be transm itted, less efficiently via bone, to the cochlea. Thus if a patient has a positive Rinne’s test it dem onstrates that air conduction is better than bone conduction and they therefore do not have a significant conductive hearing loss. If Rinne’s test is negative, sound is transm itted m ore efficiently via bone than air, and this dem onstrates a conductive hearing loss. In sensorineural hearing loss Rinne’s test should be positive. There is a caveat to this, the false negative Rinne’s test. This can be found in total unilateral sensorineural hearing loss (i.e. a ‘dead’ ear). On testing bone conduction the sound travels to the good (i.e. untested) ear and sounds louder than when the fork is held next to the external auditory m eatus on the side being tested – the patient reports that bone conduction is better than air conduction giving a false negative Rinne’s test. To com plete your exam ination thank the patient. Figure 2 Rinne’s test – testing BC. Figure 3 Rinne’s test – testing AC. 5

  3. When perform ing the tuning fork tests it is im portant to realise, as stated at the beginning, that results of tuning fork tests are not straightforward, nor particularly helpful in diagnosis, where patients have bilateral hearing loss of (a) different am ounts, (b) different types or (c) m ixed types. Test Norm al Conductive Hearing Loss BC > AC (Rinne’s Negative) Sensorineural Hearing Loss Rinne’s AC > BC (Rinne’s Positive) AC > BC * (Rinne’s Positive) Sound heard in good ear Weber’s Sound heard in m idline Sound heard in affected ear Table 1 Interpretation of Rinne’s and Weber’s tests. * Unless total sensorineural hearing loss when a False Negative Rinne’s may occur. References [1] Jopling, H. The principles of clinical exam ination The Journal of Clinical Exam ination (2006) 1: 3-6 [2] Chole RA, Cook GB. The Rinne test for conductive deafness. A critical reappraisal. Arch Otolaryngol Head Neck Surg. 1988 Apr;114(4):399- 403. [3] Stankiewicz JA, Mowry HJ. Clinical accuracy of tuning fork tests. Laryngoscope. 1979 Dec;89(12):1956-63. [4] Miltenburg DM. The validity of tuning fork tests in diagnosing hearing loss. J Otolaryngol. 1994 Aug;23(4):254-9. [5] Burkey JM, Lippy WH, Schuring AG, Rizer FM. Clinical utility of the 512-Hz Rinne tuning fork test. Am J Otol. 1998 Jan;19(1):59-62. [6] Browning GG. Clinical Otology & Audiology, 2nd Edition. Arnold; 2001. [7] Seidel HM, Ball JW, Dains JE, Benedict GW. Mosby’s Guide to Physical Exam ination, 3rd Edition. Mosby; 1995 [8] Munro JF, MacLeod J, Cam pbell CR.Macleod’s Clinical Exam ination, 11th Edition. Churchill Livingstone; 2005 [9] O’Donoghue GM, Narula AA, Bates GJ. Clinical ENT, 2nd Edition. Singular Publihing; 2000. 6