NMS Q&A Family Medicine

22 NMS Q&A Family MedicineTABLE 3–1 Audiogram Showing the Noise-Induced V Shapedb 500 Hz 1 kHz 2 kHz 3 kHz 4 kHz 5 kHz 6 kHz 7 kHz 8 kHz010 x x x x x20 x x3040 xthan “normal” at the top to up to 60 db loss going downwardon the chart). The horizontal axis shows the soundfrequencies in the hearing range in cps or Hertz movingupward in frequency from left to right (connecting thepoints of hearing threshold normal hearing would be aflat line across the top of the graph). The 4,000 cps is thefirst and most severely affected frequency (deepest loss ona tonal audiogram) involved in noise-induced hearingloss. As the 4,000 cps (4 kHz) frequency is more deeplyaffected, the adjacent frequencies become involved (e.g.,3,000 and 5,000 cps), producing on the audiogram thenoise-induced “V.” See Table 3–1 . A flat audiogram showingdepression of threshold uniformly across the frequenciesis more characteristic of a conductive hearing lossthan of a sensorineural loss. Early involvement of conversationalfrequencies is not a strong characteristic of noiseinducedloss, as most conversation occurs at lowerfrequencies. However, when conversation is effected,higher voices such as females’ are the first problems to benoted. As a sensorineural hearing loss, noise-induced lossis not as amenable to a hearing aid as are conductivelosses, although developing technology has resulted ingreat improvement in this deficit.17. The answer is C. Acoustic neuroma is the most likelycause of the symptoms. Acoustic neuroma is a slowlygrowing benign growth, the most common of cerebellopontineangle tumors, comprising 78% of that category.Gradual expansion may involve other cranial nerves aswell, for example, the trigeminal and visual dysfunctioncan result through space occupation. Acoustic neuromaspresent with hearing loss, sensorineural to be sure, in littlemore than 50% of cases, the remainder presenting withtinnitus, vertigo (9%), or unsteadiness. Females areinvolved more than males in a ratio of 3:2. When bilateral,acoustic neuroma may be a manifestation of Von Recklinghausen’sdisease. Both otitis media and cerumenimpaction cause conductive hearing loss. Acoustic traumacauses sensory hearing loss but comes on more slowly andis associated with clearly identified causes by history.Although Meniere’s disease may present as isolated hearingloss without vertigo (and acoustic neuroma with vertigoand tinnitus, much like Meniere’s disease), the courseor Meniere’s disease is always episodic rather than steadilyprogressive. The perceived color change does not fit withother findings in this case and thus must be attributed toan unrelated cause, for example, a vascular variation onthe tympanic membrane.18. The answer is C. Cholesteatoma. Owing to chronicotitis media, this complication is nearly always the resultof a nonhealing perforated tympanic membrane. Theinteraction of the ectodermal and entodermal elements ofthe eardrum combine to form an expanding “benign”mass that occupies space and may destroy the ossicularchain, impinge on the facial nerve, and lead to complicationssuch as meningitis. Treatment is usually surgical.Neither otosclerosis nor Meniere’s disease manifests anyvisible abnormalities on examination. Although this conditionmay resemble chronic external otitis in that the latterwould show debris in the canal, the area of thetympanic membrane would be expected to be nonvisualizeddue to the debris. Bullous myringitis is easily seen asa deformity of a recognizable eardrum.19. The answer is B. Vertigo of peripheral (vestibular)origin is characterized by violent symptoms after a latentperiod of 15 to 60 seconds, after motion of the head affectingthe semicircular canals, for example, the Hallpikemaneuver, in which the patient is told to lie back to thesupine position while the examiner holds the patient’shead and turns it simultaneously 90 degrees and thepatient told to stare onto a blank wall. Symptoms of vertigoand the sign of horizontal nystagmus after a latentperiod of 30 to 60 seconds upon motion of the headaffecting the semicircular canals is characteristic ofperipherally based vertigo. This syndrome may be causedby vestibular neuronitis, benign positional vertigo, andMeniere’s disease, among others, although Meniere’s usuallyis associated with hearing loss and tinnitus – andwould be expected to recur). The nystagmus due to aperipheral cause manifests fast and slow phases in nystagmusand tends to be relieved by fixation of gaze upon afixed point. Nystagmus and symptoms that occur immediatelyupon completing the maneuver indicate centrallybased vertigo. That nystagmus is pendular in that the eyemovements are most rapid at the midpoint of the movementand the movement is symmetrical.20. The answer is D. The patient has ethmoid sinusitis(ethmoiditis). The most important reason to diagnoseand treat this condition within a day or two is the feared