If one dissects the anatomy of the external, middle, and internal ear one can obtain an excellent list of conditions to be considered in the differential diagnosis of tinnitus and deafness (Table 58). Beginning in the external canal, impacted cerumen and foreign bodies are occasionally the cause. Next, visualizing the drum, one is reminded of otitis media, herpes zoster oticus, myringitis bullosa, and traumatic rupture of the drum. Behind the drum are the auditory ossicles; these little bones should prompt the recall of otosclerosis. The chordae tympani nerve passes behind the drum on its way to the jaw and tongue. This structure should suggest the tinnitus of Costen temporomandibular joint syndrome. The eustachian tube should remind one of the aerotitis connected with flying and the serous otitis connected with blockage of the tube from upper respiratory infections and allergies. Behind the middle ear, the connecting passages of the mastoid bones suggest mastoiditis. Moving deeper to the inner ear, one is reminded of toxic labyrinthitis from salicylates, quinine, streptomycin, gentamycin, and a host of other drugs. Classified here is also the “toxic” labyrinthitis of uremia, anemia, and leukemia. Syphilis, typhoid, and other bacteria may occasionally invade the inner ear, but most infections here are viral. The chronic granulomatous cholesteatoma should be recalled. In visualizing the labyrinth, one cannot help but recall Ménière disease, a prominent cause of tinnitus and deafness. Severe head injuries may cause tinnitus and traumatic labyrinthitis. Connecting the auditory apparatus to the brain is the auditory nerve, and acoustic neuromas are quickly brought to mind in the differential diagnosis. The nerve, brainstem, and brain, however, are affected by numerous conditions, and it would be well to recall them with the mnemonic VINDICATE.
TINNITUS AND DEAFNESS
I C A T E Intoxication Congenital Autoimmune Trauma Endocrine Allergic Myxedema
V—Vascular lesions include aneurysms and occlusions of the vertebral–basilar or internal auditory arteries. Hypertension and migraine may cause intermittent spasms of these arteries with tinnitus and occasional deafness. I—Inflammatory lesions include syphilis, tuberculous and bacterial meningitis of other organisms, and many febrile illnesses that may lead to transient tinnitus and deafness. Viral encephalitis, rubella in utero, and mumps may cause tinnitus and deafness. N—Neoplasms include acoustic neuromas, meningiomas, and occasional gliomas or metastatic carcinomas and sarcomas. D—Degenerative disorders remind one of the idiopathic symmetric tinnitus and deafness in the aged population (presbycusis) and the dominant progressive nerve deafness diseases considered under the congenital category. Paget disease might also be considered here. I—Intoxication. It is uncertain whether drugs and certain poisons such as lead, phosphorus, mercury, and aniline dyes affect the nerve or cochlea more, but it is well to remember them here also. C—Congenital disorders that may cause tinnitus and deafness include maternal rubella and all the hereditary causes of sensorineural deafness. Hallgren disease, Alström syndrome, Refsum disease, and Treacher Collins syndrome are only a few of these. Some of these disorders are associated with lesions in other organs. For example, Alport syndrome is the combination of hereditary deafness and nephritis. The aura of tinnitus in epilepsy should be recalled here. A—Autoimmune diseases that cause involvement of the acoustic nerve and its tributaries include multiple sclerosis and postinfectious encephalomyelitis. T—Traumatic conditions include skull fractures and the postconcussion syndrome. The occupational tinnitus and deafness of continuous noise must also be considered here. E—Endocrine diseases include hypothyroidism, acromegaly, and diabetic neuritis.
When a patient complains of tinnitus and deafness, a good occupational history is essential. Gradual onset of unilateral deafness should be considered an acoustic neuroma until proven otherwise. The combination of other symptoms and signs is the key to a clinical diagnosis. Thus tinnitus, deafness, and vertigo suggest Ménière disease. Almost total unilateral deafness (sudden in onset in a diabetic) suggests diabetic neuritis. A similar episode can occur in syphilis, but vertigo is also often present. Tinnitus and vertigo following a head injury suggest traumatic myringitis, labyrinthitis, or postconcussion syndrome. If there is total deafness with the tinnitus and vertigo, a basilar skull fracture should be considered. Tinnitus and headache suggest migraine. Diagnostic studies that should be done in all cases are audiograms, caloric tests, and x-rays of the skull, petrous bones, and mastoids. If an acoustic neuroma is suspected, tomography of the petrous bones, a CT scan or magnetic resonance imaging (MRI), and basilar myelography may be indicated. Syphilis and multiple sclerosis require a spinal tap to assist in diagnosis. Angiography and EEGs may be required in selected cases.
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Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2008 Williams & Wilkins.
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Title: Differential Diagnosis in Primary Care Authors: R. Douglas Collins MD, FACP Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 0-7817-6812-8 
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