Noninflammatory Diseases ofthe labyrinth Primary involvement of the cochlea, vestibular apparatus, or the eighth cranial nerve with spread to the contiguous structures is characteristic of this group of diseases. Unfortunately, the common involvement of the vestibular labyrinth and its widespread central nervous connections in systemic illness makes difficult the differentiation of symptoms due to this cause from those due to specific vestibular disease The principal subjective symptoms---vertigo(Hz ) deafness, and tinnitus--are all common to this group of disorders, again creating problems of diagnosis. Rap id progress in methods of examination of cochlear and vestibular function has greatly aided in the differentiation of these diseases and thus removed a great deal of the confusion which was present in the past Vertigo and dizziness Vertigo is defined as a hallucination of movement this may be a sensation of turning, sp inning, falling, rocking, etc. Dizziness, although commonly used by the patient as a term to describe the above sensations refers to less severe and distinct sensations of giddiness, faintness confusion, blankness, or unsteadiness. This differentiation is important since vertigo arises from disturbance of the vestibular end-organ vestibular nerve, or vestibular nucleus. Dizziness may arise from mild
Noninflammatory Diseases of the Labyrinth Primary involvement of the cochlea, vestibular apparatus, or the eighth cranial nerve with spread to the contiguous structures is characteristic of this group of diseases. Unfortunately, the common involvement of the vestibular labyrinth and its widespread central nervous connections in systemic illness makes difficult the differentiation of symptoms due to this cause from those due to specific vestibular disease. The principal subjective symptoms---vertigo(眩晕), deafness, and tinnitus--are all common to this group of disorders, again creating problems of diagnosis. Rapid progress in methods of examination of cochlear and vestibular function has greatly aided in the differentiation of these diseases and thus removed a great deal of the confusion which was present in the past. Vertigo and Dizziness Vertigo is defined as a hallucination of movement. This may be a sensation of turning, spinning, falling, rocking, etc. Dizziness, although commonly used by the patient as a term to describe the above sensations, refers to less severe and distinct sensations of giddiness, faintness, confusion, blankness, or unsteadiness. This differentiation is important, since vertigo arises from disturbance of the vestibular end-organ, vestibular nerve, or vestibular nucleus. Dizziness may arise from mild
disturbance of the vestibular apparatus but usually indicates distur bance in other regions An analogy given by Cawthoru helps to clarify the types of disturbance of the poripheral vestibular apparatus resulting in vertigo This mechanism may be likened to a twin-engined airplane. When both engines are running normally and the controls are properly operating, the airplane flies on a straight course. If one engine suddenly fails, the plane s violently diverted off its course by the unopposed action of the normally running engine. By readjusting the controls, after a short period the pilot is able to fly on a straight course again, though turning or a sudden gust of wind will have a more distur bing effect than when the two engines are working normally. In another situation the faulty engine may start up again, and even if it does not return to its normal speed, all is well provided it runs steadily. However, should the faulty engine repeatedly fail and recover, the result will be more disturbing than having a dead engine. In another situation one engine may fail to work properly only when the airplane is in a certain position, such as in a steep bank to the left, but will return to normal as soon as the airp lane straightens out Finally, if one engine loses power slowly, the pilot almost imperceptibly is able to readjust the controls without deviating from his course The airp lane engines may be directly compared to the set of vestibular end-organs in each labyrinth, Each of the types of failure may occur in
disturbance of the vestibular apparatus but usually indicates disturbance in other regions. An analogy given by Cawthoru helps to clarify the types of disturbance of the poripheral vestibular apparatus resulting in vertigo. This mechanism may be likened to a twin-engined airplane. When both engines are running normally and the controls are properly operating, the airplane flies on a straight course. If one engine suddenly fails, the plane is violently diverted off its course by the unopposed action of the normally running engine. By readjusting the controls, after a short period the pilot is able to fly on a straight course again, though turning or a sudden gust of wind will have a more disturbing effect than when the two engines are working normally. In another situation the faulty engine may start up again, and even if it does not return to its normal speed, all is well provided it runs steadily. However, should the faulty engine repeatedly fail and recover, the result will be more disturbing than having a dead engine. In another situation one engine may fail to work properly only when the airplane is in a certain position, such as in a steep bank to the left, but will return to normal as soon as the airplane straightens out. Finally, if one engine loses power slowly, the pilot almost imperceptibly is able to readjust the controls without deviating from his course. The airplane engines may be directly compared to the set of vestibular end-organs in each. labyrinth, Each of the types of failure may occur in
man, resulting in each case with loss of equilibrium and a type of vertigo evaluating vertigo, the history is of great importance. The following information should be elicited(引出) 1. Whether the symptom experienced is true vertigo. If the comp laint does consist of a sensation of motion or turning. the origin lies in the vestibular apparatus; otherwise, other regions must be subjected to examination and evaluation 2. The pattern of the vertigo. It is important to note whether the attacks are spontaneous or precip itated(突如其来的) by movement. The presence of paroxysmal attacks separated by periods of relative freedom from symptoms indicates a different pathologic condition than more or less continuous dizziness 3. The degree of vertigo. Vertigo arising in the labyrinth is usually accompanied by nausea and often vomiting. Less specific forms may be milder and may arise from any part ofthe body 4. The association of hearing loss or tinnitus with dizziness is a definite aid to localization. Complete audiometric evaluation is essential to the examination of the dizzy patient, since these diseases may affect the vestibular apparatus alone the cochlear apparatus alone, or both together Tinnitus This may be objective in rare instances(a sound which may be heard
man, resulting in each case with loss of equilibrium and a type of vertigo. In evaluating vertigo, the history is of great importance. The following information should be elicited (引出): 1. Whether the symptom experienced is true vertigo. If the complaint does consist of a sensation of motion or turning, the origin lies in the vestibular apparatus; otherwise, other regions must be subjected to examination and evaluation 2. The pattern of the vertigo. It is important to note whether the attacks are spontaneous or precipitated(突如其来的) by movement. The presence of paroxysmal attacks separated by periods of relative freedom from symptoms indicates a different pathologic condition than more or less continuous dizziness. 3. The degree of vertigo. Vertigo arising in the labyrinth is usually accompanied by nausea and often vomiting. Less specific forms may be milder and may arise from any part of the body. 4. The association of hearing loss or tinnitus with dizziness is a definite aid to localization. Complete audiometric evaluation is essential to the examination of the dizzy patient, since these diseases may affect the vestibular apparatus alone, the cochlear apparatus alone, or both together. Tinnitus This may be objective in rare instances (a sound which may be heard
by the examiner) but is usually a subjective sensation of sound arising from within the head. Tinnitus may vary in intens ity and may be continuous or intermittent. Subjectively loud and continuous tinnitus may produce a severe handicap(pal)to the individual Tinnitus is associated with hearing loss arising from disorders of the sound conduction system, the cochlea, or the neural pathways of the cochlear nerve. Patients describe the sound in various ways, but the examiner should attempt to obtain a description of the sound with which both the patient and the doctor is familiar. In general the sounds experienced will range from predominant!y(主要地) low frequencies (like a ventilating fan or sea shell sound) to wide-range white noise(a rushing sound commonly experienced in Meniere's disease) or high-p itched noise, whistles, or insect sounds(which frequently may be matched on the audiometer) Conductive hearing loss usually produces a low-pitched continuous sound which, if combined with inflammation, becomes pulsating High-pitched continuous or intermittent tinnitus is associated with high tone hearing loss and is an important and early sign of drug intoxication ( aspirin, digitalis洋地黄, quinine, dihydrostreptomycin,eec Pulsating low-pitched tinnitus without hearing loss is an important early symptom of glomus jugulare tumors of the middle ear. It is also associated with occlusive disease of the carotid artery which will at times
by the examiner) but is usually a subjective sensation of sound arising from within the head. Tinnitus may vary in intensity and may be continuous or intermittent. Subjectively loud and continuous tinnitus may produce a severe handicap(阻碍)to the individual. Tinnitus is associated with hearing loss arising from disorders of the sound conduction system, the cochlea, or the neural pathways of the cochlear nerve. Patients describe the sound in various ways, but the examiner should attempt to obtain a description of the sound with which both the patient and the doctor is familiar. In general the sounds experienced will range from predominantly（主要地） low frequencies (like a ventilating fan or sea shell sound) to wide-range white noise (a rushing sound commonly experienced in Meniere's disease) or high-pitched noise, whistles, or insect sounds (which frequently may be matched on the audiometer). Conductive hearing loss usually produces a low-pitched continuous sound which, if combined with inflammation, becomes pulsating. High-pitched continuous or intermittent tinnitus is associated with high tone hearing loss and is an important and early sign of drug intoxication (aspirin, digitalis 洋 地 黄 , quinine, dihyclrostreptomycin, etc.). Pulsating low-pitched tinnitus without hearing loss is an important early symptom of glomus jugulare tumors of the middle ear. It is also associated with occlusive disease of the carotid artery, which will at times
produce an audible bruit Other than relieving a conductive hearing loss there is no effective treatment of tinnitus. Even section of the eighth nerve in most cases does not result in cessation( IE)of tinnitus. Patients suffering from this symptom deserve a full and honest exp lanation of the nature of the disorder so that natural anxiety does not cause exaggeration of the severity of the symptoms. Barbiturates and tranquilizers are rarely indicated for use in this condition for in most instances patients are able to adapt to the presence of tinnitus and ignore it Examination and Differential Diagnosis The main causes of vertiginous labyrinthine distur bance are 1. Acute toxic labyrinthitis 2. Meniere's disease 3. Paroxysmal positional vertigo (postural verti 4. Vestibular neuronitis(前庭神经元炎) 5. Vertebral- basilar artery insufficiency(椎基底动脉供血不足) 6. Trauma 7. Tumor(Acoustic neurinoma The main types of distur bances to be differentiated from these diseases are the following 1. Disease of the cerebellum, especially vascular disease and tumors 2. Disease of the proprioceptive system
produce an audible bruit. Other than relieving a conductive hearing loss, there is no effective treatment of tinnitus. Even section of the eighth nerve in most cases does not result in cessation(停止) of tinnitus. Patients suffering from this symptom deserve a full and honest explanation of the nature of the disorder so that natural anxiety does not cause exaggeration of the severity of the symptoms. Barbiturates and tranquilizers are rarely indicated for use in this condition, for in most instances patients are able to adapt to the presence of tinnitus and ignore it. Examination and Differential Diagnosis The main causes of vertiginous labyrinthine disturbance are: 1. Acute toxic labyrinthitis 2. Meniere's disease 3. Paroxysmal positional vertigo (postural vertigo) 4. Vestibular neuronitis（前庭神经元炎） 5. Vertebral-basilar artery insufficiency(椎基底动脉供血不足) 6. Trauma 7. Tumor (Acoustic neurinoma) The main types of disturbances to be differentiated from these diseases are the following: 1. Disease of the cerebellum, especially vascular disease and tumors 2. Disease of the proprioceptive system
3. Cerebral anoxemia, particularly mild arteriosclerosis, postural hypotension, and anemia 4. Endocrine disease, particularly hypothyroidism; and female hormonal disturbance 5. Epilepsy(癫痫) Nonvertiginous labyrinthine disease affects primarily the cochlea and includes the following 1. Congenital and neonatal hearing loss 2. Familial deafness Presbycusis(老年性耳聋) 4. Drug toxicity 5 Ototropic viral disease(耳带状疱疹) 6. Noise-induced hearing loss 7. Sudden idiopathic hearing loss(突发性耳聋) 8 Otosclerosis(耳硬化症) Examination of the patient with labyrinthine symptoms(vertigo hearing loss, and tinnitus)should include caloric examination and hearing evaluation. The latter should consist of air and bone audiometry; speech audiometry; Bekesy audiometry, when indicated; and determination of recruitment. If the examiner does not have the equipment to perform these tests, the patient should be referred to a Speech and Hearing center where they may be performed. In general, all patients with unilateral
3. Cerebral anoxemia, particularly mild arteriosclerosis, postural hypotension, and anemia 4. Endocrine disease, particularly hypothyroidism; and female hormonal disturbance 5. Epilepsy（癫痫） Nonvertiginous labyrinthine disease affects primarily the cochlea and includes the following: 1. Congenital and neonatal hearing loss 2. Familial deafness 3. Presbycusis(老年性耳聋). 4. Drug toxicity 5. Ototropic viral disease(耳带状疱疹) 6. Noise-induced hearing loss 7. Sudden idiopathic hearing loss（突发性耳聋） 8. Otosclerosis （耳硬化症） Examination of the patient with labyrinthine symptoms (vertigo, hearing loss, and tinnitus) should include caloric examination and hearing evaluation. The latter should consist of air and bone audiometry; speech audiometry; Bekesy audiometry, when indicated; and determination of recruitment. If the examiner does not have the equipment to perform these tests, the patient should be referred to a Speech and Hearing center where they may be performed. In general, all patients with unilateral
symptoms or findings or with widely differing findings in the two ears should have the comp lete battery oftests described above n recent times, electronystagmography(眼震电图描记法)has enabled accurate quantitative measurement of the ocular responses to caloric and rotatory tests of the vestibular apparatus and should be employed when available Radiographic examination of the inner ear includes the Stenvers view and the Town-Chamber lain view. These projections enable visualization of the petrous bone and internal auditory canal. In instances CTor Mr is essential in the work-up ofthese problems In many cases complete neurologic examination and spinal fluid analysis are necessary to provide an exact diagnosis MENIERES DISEASE In 1848 Prosper Meniere described the symptom complex bearing his name, illustrating the report by citing(l )the case of a young girl who died from labyrinthine hemorrhage in order to prove definitely the anatomic origin of the symptoms. Knowledge of the pathologic process (although anticipated by G. Portmann, who likened the disease to glaucoma) was provided by hall ike and Cairns in 1938, who reported
symptoms or findings or with widely differing findings in the two ears should have the complete battery of tests described above. In recent times, electronystagmography(眼震电图描记法) has enabled accurate quantitative measurement of the ocular responses to caloric and rotatory tests of the vestibular apparatus and should be employed when available. Radiographic examination of the inner ear includes the Stenvers view and the Town-Chamberlain view. These projections enable visualization of the petrous bone and internal auditory canal. In most instancesCT or MR is essential in the work-up of these problems. In many cases complete neurologic examination and spinal fluid analysis are necessary to provide an exact diagnosis. MENIERE'S DISEASE In 1848 Prosper Meniere described the symptom complex bearing his name, illustrating the report by citing (引用) the case of a young girl who died from labyrinthine hemorrhage in order to prove definitely the anatomic origin of the symptoms. Knowledge of the pathologic process (although anticipated by G. Portmann, who likened the disease to glaucoma) was provided by Hallpike and Cairns in 1938, who reported
the changes of dilatation of the endolymphatic system accompanied by degeneration(u )of the sensory elements of the cochlea and vestibular apparatus. Since that time, microscop ic examination of many involved temporal bones has clarified the exact pathologic picture, while the etiology remains obscure Pathology. Knowledge of the pathologic process in Meniere's disease has been gained by study of temporal bones of individuals suffering from this disease. The earliest findings are dilatation of the scala media(psr) of the cochlea and the saccule(Ek E ). This dilatation in the cochlea is evidenced by stretching of Reissner's membrane rather than of the basilar membrane. as the disease progresses, there is degeneration of the organ of Corti with loss of hair cell population. Tearing of reissner's membrane with reattachment further out on the scala vestibuli(前庭阶) has been demonstrated in a few temporal bones. Dilatation of the utricle(椭圆囊) and membranous semicircular canals is not often found, occurring late in the disease or in severe cases It has been demonstrated by electron microscopic study that the normal secretory endothelium of the endolymphatic sac has disappeared and been rep laced with a simple flattened ep ithelium in patients with Meniere's disease. Some but not all human temporal bone specimens have demonstrated various degrees of narrowing and fibrosis of the vestibular aqμ educt(前庭导水管), reducing or obliterating the functional lumen of
the changes of dilatation of the endolymphatic system accompanied by degeneration(恶化) of the sensory elements of the cochlea and vestibular apparatus. Since that time, microscopic examination of many involved temporal bones has clarified the exact pathologic picture, while the etiology remains obscure. Pathology. Knowledge of the pathologic process in Meniere's disease has been gained by study of temporal bones of individuals suffering from this disease. The earliest findings are dilatation of the scala media(中阶) of the cochlea and the saccule(球囊). This dilatation in the cochlea is evidenced by stretching of Reissner's membrane rather than of the basilar membrane. As the disease progresses, there is degeneration of the organ of Corti with loss of hair cell population. Tearing of Reissner's membrane with rcattachment further out on the scala vestibuli（前庭阶） has been demonstrated in a few temporal bones. Dilatation of the utricle（椭圆囊） and membranous semicircular canals is not often found, occurring late in the disease or in severe cases. It has been demonstrated by electron microscopic study that the normal secretory endothelium of the endolymphatic sac has disappeared and been replaced with a simple flattened epithelium in patients with Meniere's disease. Some but not all human temporal bone specimens have demonstrated various degrees of narrowing and fibrosis of the vestibular aqueduct（前庭导水管）, reducing or obliterating the functional lumen of
the endolymphatic duct(内淋巴管). Valvassori has developed projections to visualize the vestibular aqueduct by polytomography and, together with others, has reported a high incidence of narrowing or nonvisualization ofthis structure in patients with meniere's disease The pathology is usually unilateral, but may become bilateral in as many as 25% of patients with longer durations ofobservation Etiology. Although it is clear that this is a disease affecting the fluid physiology of the endolymphatic system, the origin of this distur bance has not been defined. It is not as yet known whether the primary disturbance is one of hypersecretion, hypoabsorption, or a disturbance of balance between both secretion and absorption. Also possible is a deficit (不足额) of membrane permeability(渗透性) or alteration of osmotic pressure(iiEl) relationships. It is clear that all the energy required for the function of the cochlea is supplied by the stria vascularis(血管纹) and transported by the endolymph, showing that a rapid production of this fluid is needed. The exact site of absorption is not known, but mo workers consider it to take place either in the endoly mphatic sac or in the stria vascularis The most popular theories ofetiology have been 1. Local distur bance of salt and water balance, leading to edema"of the endolymph 2. Disturbance of the autonomic regulation of the endolymphatic
the endolymphatic duct （ 内淋 巴管 ）. Valvassori has developed projections to visualize the vestibular aqueduct by polytomography and, together with others, has reported a high incidence of narrowing or nonvisualization of this structure in patients with Meniere's disease. The pathology is usually unilateral, but may become bilateral in as many as 25% of patients with longer durations of observation. Etiology. Although it is clear that this is a disease affecting the fluid physiology of the endolymphatic system, the origin of this disturbance has not been defined. It is not as yet known whether the primary disturbance is one of hypersecretion, hypoabsorption, or a disturbance of balance between both secretion and absorption. Also possible is a deficit （不足额）of membrane permeability（渗透性）or alteration of osmotic pressure（渗透压）relationships. It is clear that all the energy required for the function of the cochlea is supplied by the stria vascularis（血管纹） and transported by the endolymph, showing that a rapid production of this fluid is needed. The exact site of absorption is not known, but most workers consider it to take place either in the endolymphatic sac or in the stria vascularis. The most popular theories of etiology have been: 1. Local disturbance of salt and water balance, leading to "edema" of the endolymph. 2. Disturbance of the autonomic regulation of the endolymphatic
system 3. Local allergy of the inner ear, causing edema and disturbance in autonomic control 4. Vascular disturbance of the inner ear especially of the stria vascular s(血管纹 5. Local labyrinthine manifestation of systemic metabolic disease involving either thyroidor glucose metabolism or both 6. Alteration in the relationship between perilymphatic, and endolymphatic pressure dynamics, which may be related to anatomic alterations in both the endolymphatic duct(内淋巴管)and, the cochlear aqueduct(耳蜗导水管) 7. Disturbance of the endolymphatic duct or sac, Causing interference with absorption of endolymph. H. House has described a case with an otosclerotic focus block ing the endolymphatic duct which also showed distention of the membranous labyrinth This author's experience has led to yet another hypothesis concerning the pathogenesis of Menieres disease. The concept is of primary (undefined) or inflammatory or metabolic process acting on the endolymphatic sac and duct, which causes involution of the endothelium and functional narrowing or obliteration of the endolymphatic duct as seen by x-ray examination. These changes may be latent for varying periods of time but become manifest when stress acts upon the fluid
system. 3. Local allergy of the inner ear, causing edema and disturbance in autonomic control. 4. Vascular disturbance of the inner ear especially of the stria vascularis(血管纹). 5. Local labyrinthine manifestation of systemic metabolic disease involving either thyroid or glucose metabolism or both. 6. Alteration in the relationship between perilymphatic, and endolymphatic pressure dynamics, which may be related to anatomic alterations in both the endolymphatic duct（内淋巴管）and, the cochlear aqueduct（耳蜗导水管）. 7. Disturbance of the endolymphatic duct or sac, Causing interference with absorption of endolymph. H. House has described a case with an otosclerotic focus blocking the endolymphatic duct which also showed distention of the membranous labyrinth. This author's experience has led to yet another hypothesis concerning the pathogenesis of Meniere's disease. The concept is of primary (undefined) or inflammatory or metabolic process acting on the endolymphatic sac and duct, which causes involution of the endothelium and functional narrowing or obliteration of the endolymphatic duct as seen by x-ray examination. These changes may be latent for varying periods of time but become manifest when stress acts upon the fluid