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Abrupt (Sharp Cut) Type Sensorineural Hearing Loss
Auris·Nasus·Larynx (Tokyo) 6,13-21,1979
ABRUPT (SHARP CUT) TYPE SENSORINEURAL HEARING LOSS -A HUMAN TEMPORAL BONE STUDYYasuya NOMURA, M.D., and Ken KITAMURA, M.D. Department of Otolaryngology, University of Tokyo Hongo, Bunkyo-ku, Tokyo, Japan
Histopathology of a case of bilateral sensorineural hearing loss of abrupt (sharp cut) type is reported. While there was a 45 dB gap in threshold between 1,000 Hz and 2,000 Hz bilaterally, the patient had a good hearing at 1,000 Hz and lower frequencies. The patient was suffering from Takayasu's arteritis. Major histopathological findings were as follows: Almost complete loss of the outer hair cells from the basal end to 12 mm area in the left cochlea (length: 30.5 mm) and 13 mm in the right (length: 31.5 mm). The inner hair cell of the same region was also missing in the left cochlea, and to a lesser degree in the right. There was a clear separation between the normal and the pathological organ of Corti. Marked loss of the cochlear neuron was noted in the same region. Blood vessels within the cochlea and the internal auditory meatus were normal. Bilateral abrupt (sharp cut) type sensorineural hearing loss with unknown etiology is a group of inner ear disease due to abiotrophy of the organ of Corti and cochlear neuron. Disposition or hereditary factor possibly plays an important role in the development of hearing loss. Bilateral sensorineural hearing loss of an abrupt type is encountered not infrequently in clinic. Both ears reveal a similar audiogram. Certain causes may be responsible for this type of audiogram, such as, ototoxic drugs and acoustic trauma. However, only abrupt type hearing loss of unknown etiology is dealt with in this paper. Onset of hearing loss is insidious. Hearing loss does not show rapid progress. Patients with this audiogram often do not recognize presence of hearing loss, particularly when hearing loss is only in higher frequencies. It is conceivable that lesions in the auditory organ might be limited, and that there must be a clear separation of the lesions from the normal area. There are several histopathological reports in which the temporal bone of abrupt type hearReceived for publication October 1, 1978 13
14
Y. NOMURA and K. KITAMURA
ing loss was mentioned in audiometric correlation. However, there are only a few papers on the bilateral abrupt type hearing loss. The purpose of this paper is to report and discuss the histopathology of the temporal bones of a case of Takayasu's arteritis who showed bilateral sensorineural hearing loss of abrupt type. CASE HISTORY
In December, 1964, a 45-year-old man was first seen at the ENT Clinic of the University of Tokyo. His chief complaint was bilateral hearing loss. He had no known history of ear diseases. In 1948, when he was 29 years of age, he had noticed that his bilateral radial pulse was not palpable. Angiographic study had 125
250
500
1000
2000
4000
8000 Hz
-10 0~------------------~-------------------4
10 20 30
40 50
60 70 80
90 dBL-__~____~____L -_ _~____~_ _~____~_ _~
Fig. 1. Audiogram and histograms of the right cochlea. The black areas represent the estimated degree of loss or degeneration of the inner hair cells, outer hair cells, cochlear neurons and stria vascularis. * Cyst in the stria vascularis.
SHARP CUT HEARING LOSS
15
revealed that his bilateral subclavian arteries were obliterated. Since then, corticosteroid had been administered under the diagnosis of Takayasu's arteritis. The patient was referred to us from medical clinic. Routine ENT check up revealed no abnormal findings except in the audiogram. The audiogram taken 4 months prior to his termination showed almost similar, bilateral abrupt (sharp cut) type hearing loss (Figs. 1 and 2). In 1969, he died of cardiac failure due to aortic insufficiency. Autopsy revealed the followings. There was dilatation of the aorta, the inner surface of which showed fine wrinkles and decrease of elasticity. Histologically, there was thickening of the adventitia, disruption of elastic tissue of the media and fibrous thickening of the intima. Marked focal lymphocytic infiltration was found. Arteries involved were: proximal portion of the pulmonary artery, the brachiocephalic trunk, the right axillary artery, the proximal portion of the right brachial artery, the left subclavian, axillary and brachial arteries, the entire length of the 125 I
-10 0 10 20 30
X_X-\
250 I
500 I
1000
2000
4000
40 50
X"
60 70
8000 Hz
-
~
x ............
X
80 90 dB
INNER HAIR CELLS
L
Fig. 2. Audiogram and histograms of the left cochlea.
16
Y. NOMURA and K. KITAMURA
bilateral common and external carotid arteries. In contrast, the internal carotid arteries were remarkably spared. The vertebral arteries were also free from pathology. Blood vessels in the cranial cavity were normal. The temporal bones were removed 5 hr postmortem by using a Schuknecht's plug cutter and fixed immediately in 10 % formalin solution. The bones were decalcified, and embedded in celloidin. Serial horizontal sections were cut at 20 micron thickness. Every tenth section was stained with hematoxylin and eosin and studied under a light microscore. FINDINGS
The external and middle ear showed no pathology in both temporal bones.
Fig. 3 Organ of Corti in the right cochlea. A : normal organ of Corti (middle turn). B: Two outer hair cells are missing (lower basal turn).
SHARP CUT HEARING LOSS
17
The right inner ear Cochlea: Extensive lesions of the organ of Corti were noted in the basal
turn. From the basal end up to 13 mm area, the outer hair cells were almost completely missing. The inner hair cells were partly present in the same area. In the remaining area of the cochlea, the outer and inner hair cells were well preserved (Figs. 1 and 3). The cochlear neurons were almost totally missing up to 9 mm area from the basal end and to a lesser degree from 9 mm to 13 mm area in the basal turn. The spiral vessel under the tunnel of Corti, vas spirale, looked normal throughout the cochlea, even in the area where the outer hair cells were missing. The stria vascularis was atrophic in the lower basal turn. There was a cyst in the stria vascularis near the apical end (Fig. 4). The external sulcus and its lining cells, and spiral prominence were normal. The inferior cochlear vein and the cochlear aqueduct were normal. Vestibule: The neuroepithelium of the macula utriculi and the cristae were essentially normal. Partial loss of neuroepithelium was observed in the anterior portion of the macula sacculi. The endolymphatic duct and sac were normal. Internal auditory meatus: The walls of the labyrinthine artery did not show any pathology. There was no pathology in the nerves within the internal auditory meatus. The left inner ear Cochlea: Findings in the organ of Corti were similar to those observed in
the right cochlea.
From the basal end up to 12 mm area the outer hair cells were
Fig. 4. Cyst in the stria vascularis (arrow). only in the apical end.
Ballooning of Reissner's membrane is noticed
18
Y. NOMURA and K. KITAMURA
almost completely missing (Fig. 2). There was marked degeneration and loss of inner hair cells. There was a decrea~ of cochlear neurons in the lower basal turn. The remaining inner and outer hair cells of the cochlea were well preserved. Atrophy of the stria vascularis was sporadic throughout the cochlea, marked in the lower basal turn and less pronounced toward the apex. The external sulcus cell and the spiral prominence were normal. Vestibule: The vestibular neuroepithelium was normal, except in the macula sacculi where loss of neuroepithelium was noted anteriorly. There was no collapse in the utricle and the saccule. The endolymphatic duct and sac were normal. Internal auditory meatus: The labyrinthine artery was normal. The nerves in the internal auditory meatus looked normal. DISCUSSION
The main pathological findings in the present case showed a marked loss of outer and inner hair cells and cochlear neurons in the continuous area of 0-13 mm from the basal end in the right cochlea and 0-12 mm in the left. These findings probably explain the abrupt type of the patient's audiogram. ODA (1973) proposed a term of "sharp cut" type hearing loss, in which patients have normal hearing in lower frequencies and abrupt hearing loss of greater than 40 dB per octave in higher frequencies. The present case showed bilateral "sharp cut" type hearing loss. In reviewing literature, lesions responsible for abrupt type hearing loss were either in the cochlea or in the eighth nerve. In their extensive study, CROWE, GUILD, and POLVOGT (1934) described that the pathology found in 33 ears with an abrupt high tone loss was not uniform. They classified histological lesions into 4 groups. Lesions in 24 ears (Group E of their classification) were most prominent in the basal turn, consisting of atrophy of the organ of Corti and nerve. Characteristic of this group, atrophy of the organ of Corti continued throughout the entire lower basal turn. Atrophy of the nerve was extensive in some cases, in others it was localized. In the area where the nerve had entirely disappeared, there was always total atrophy of the organ of Corti. In some sections with total absence of the organ of Corti, however, a few nerve fibers were seen in the osseous spiral lamina near the foramina nervosa. Transition from total absence of nerve fibers to normal nerves within the space of one millimeter or less was often seen in this group. In the organ of Corti, extensive and continuous type of atrophy was present in 10 ears, while in the remaining 14 ears atrophy was more localized or patchy. The extent of the atrophic area was not related to age. The external sulcus cells were always atrophic in the same area whether the total atrophy of the organ of Corti be extensive or localized. Often the extent of external sulcus cell atrophy was greater than that of the end organ atrophy.
SHARP CUT HEARING LOSS
19
In three ears (Group F), the organ of Corti was normal in appearance, but the nerve atrophy in the basal turn was greater than in the controls. In three ears (Group G), the organ of Corti was normal in appearance, but the nerve atrophy and the middle ear lesions were both more severe than in the controls. In four ears (Group H), the organ of Corti, nerve and middle ear changes were all within normal limits. According to GUILD (1953), a similar hearing loss resulted by sectioning a part of the cochlear nerve adjacent to the vestibular nerve. The operation was performed by Dr. Walter E. Dandy for a surgical treatment of Meniere's disease. In a study of presbycusis, SUGA and LINDSAY (1976) mentioned histopathological findings of temporal bones in nine cases who showed abrupt high tone loss. Lesions were mainly in spiral ganglion cells in four cases, one in the organ of Corti and four in both spiral ganglion cells and organ of Corti. Mild to severe thickening of the arterial wall in the internal auditory meatus and cochlea was found in the cases. However, they failed to find positive correlation between the thickening of the arterial wall and the degree and localization of lesions in the cochlea. An audiogram similar to the present case was presented in a 27-year-old female who received Kanamycin injection. Histological studies showed a severe loss of hair cells in the basalIS mm. The cochlear neurons show normal population (SCHUKNECHT, 1974). Audiometric correlations with histopathological findings were also substantiated in animal experimentation. NEFF (1947) mentioned that four out of 11 cats showed abrupt hearing loss after sectioning the auditory nerve. This was determined by utilizing the conditioned response method. In the present study, there was a clear separation between normal area and loss of sensory cells in the organ of Corti. The area of response for 1,000 Hz is more apical than 12-13 mm from the basal end of the cochleas in the present case. In this regard similar findings were mentioned by CROWE, GUILD, and POL VOGT (1934). The location of frequencies are different in literature. According to Koenig's scale (SCHUKNECHT, 1974), the location of the frequency for 1,000 Hz is 11.5 mm from the basal end in human cochlea of 31.5 mm length. Location of the frequency for 2,000 Hz is 6.9 mm from the same cochlea. BREDBERG (1968) located the area of 11 mm and 17 mm from the basal end of the cochlea responsible for the frequency of 4,000 Hz and 2,000 Hz, respectively. IGARASHI, SCHUKNECHT, and MYERS (1964) made a report on cochlear pathology of stimulation deafness on three patients, two with histories of exposure to high intensity noise and one of a head blow. Two of them showed audiogram characteristic of high frequency hearing loss, the most severe being for 4,000 Hz. Histopathology showed maximum injuries occurring in 10 to 12 mm regions. MCGILL and SCHUKNECHT (1976) reported that noise exposure induced degenera-
20
Y. NOMURA and K. KITAMURA
tive changes in 9 to 13 mm region of the cochlear duct, a maximum at 11 mm, in 6 cases. The cyst observed near the apical end of the stria vascularis was related to degenerative process. In strial presbycusis, cystic structures sometimes replace atrophied stria (SCHUKNECHT, 1974). Takayasu's arteritis (TAKAYASU, 1908) is described under various names which include pulseless disease (SHIMIZU and SANO, 1951) and the young female arteritis type of aortic arch syndrome (Ross and McKuSICK, 1953). The pathologic lesion is a panarteritis that seems to begin with inflammation of the adventitia, with subsequent disruption and fibrotic changes in the media, and marked proliferation of the intima. Although the exact etiology of this disease is unknown, it is suspected to be an autoimmune disease. 2,148 patients were seen by the Takayasu's Arteritis Research Committee, the Ministry of Health and Welfare of Japan, during the period of 1973-1975 (WADA, 1976). Among these patients, the followings were the most common complaints: vascular disturbances of extremities (72.3 %), constitutional symptoms which include fever, malaise, anorexia, weight loss, night sweats and arthralgias (66.8 %), cerebrovascular disturbances (64.6%), cardiac symptoms (55.2 %), and hypertension (45.4 %). Only one patient complained deafness. Hearing loss is not a common symptom of the disease. CURRIER, De JONG and BOLE (1954) reviewed 40 cases from literature and found three cases with deafness. The vertebral artery is usually free from the pathology, as was found in the present case. According to The Research Committee (1976), out of 89 autopsied cases only four cases, three bilateral and one unilateral, had the pathology in the wall of vertebral artery. It can be said that in the present case loss of sensory hair cell and cochlear neurons in the basal turn is responsible for the bilateral sharp cut type hearing loss. What then was the cause of such pathology? If Takayasu's arteritis is the cause, circulatory disturbance in the cochlea must be considered. The spiral vessel under the tunnel of Corti might be under circulatory disturbance. If the spiral vessel is functioning to maintain the organ or Corti, its malfunction may result in damaging the organ or Corti. However, in the present case the vessels within the cochlea and the internal auditory meatus showed no pathology. Thus, Takayasu's arteritis as the cause of the present hearing loss remains unsolved. According to TSUIKI (1976), bilateral abrupt type audiograms were found in 340 cases out of 3,481 cases with sensorineural hearing loss. Causes of the hearing loss of 340 cases were: unknown 211 (62.1 %), acoustic trauma 40 (11. 8 %), head trauma 25 (7.4%), drug intoxication 24 (7.1 %), of familial causes 20 (5.9%) and others (TSUIKI, personal communication). He also found 135 ears of abrupt type hearing loss in 458 ears (82 families) of hereditary deafness (TSUIKI, 1976). As was mentioned by LANGENBECK (1936), disposition of the individual is important
SHARP CUT HEARlNG LOSS
21
for the development of sensorineural hearing loss, similar III both ears (Symmetriegesetz). Histopathology of the bilateral sensorineural hearing loss of abrupt type, symmetrical in audiogram, of unknown etiology were only reported in eight cases (CROWE et al., 1934). Histological characteristics were marked loss of cochlear neuron and atrophy of the organ of Corti or loss of sensory hair cells in the basal turn. Disposition or hereditary factors could play an important role for the pathogenesis of abiotrophic hearing loss. REFERENCES BREDBERG, G.: Cellular pattern and nerve supply of the human organ of Corti. Acla Otolaryngol. Suppl. 236: 1-135, 1968. CROWE, S. J., GUILD, S. R., and POLYOGT, L. M.: Observations on the pathology of high-tone deafness. Bull. Johns Hopkins Hosp. 54: 315-379, 1934. CURRIER, R. D., De JONG, R. M., and BOLE, G. G.: Pulseless disease, central nervous system manifestations. Neurology 4: 818-830, 1954. GUILD, S. R.: The effects on hearing of partial sections of the cochlear nerve in man. Acta Ololaryngol. 43 : 199-207, 1953. IGARASHI, M., SCHUKNECHT, H. F., and MYERS, E. N.: Cochlear pathology in humans with stimulation deafness. J . Laryngol. 0101. 78: 115-123, 1964. LANGENBECK, B. : Das Symmetriegesetz der erblichen Taubheit. Z. Hals-usw. Heilk. 39 : 223261, 1936. MCGILL, T.J.!', and SCHUKNECHT, H. F.: Human cochlear changes in noise induced hearing loss. Laryngoscope 86: 1293-1302, 1976. NEFF, W. D.: The effects of partial section of the auditory nerve. J. Compa. Physiol. Psychiat. 40: 203-215, 1947. ODA, M.: Clinical studies of sharp cut type sensorineural hearing loss. Jpn. J. Otol. Tokyo 76 : 42-58, 1973. Pathology of TAKAYASU'S arteritis. Takayasu's Arteritis Research Committee, The Ministry of Health and Welfare of Japan. pp. 1-116, 1976. Ross, R . S., and McKuslcK, V. A.: Aortic arch syndromes, diminished or absent pulses in arteries arising from arch of aorta. Arch. Int. Med. 92: 701-740, 1953. SCHUKNECHT, H. F.: Pathology of the Ear. Harvard University Press, Cambridge, MA., 1974. SHIMIZU, K., and SAND, K . : Pulseless disease. J. Neuropathol. Clin. Neurol. 1: 37, 1951. SUGA, F., and LINDSAY, J. R . : Histopathological observations of presbycusis. Ann. DIal. 85: 169-184, 1976. TAKAYASU, M.: A case with peculiar changes of the central retinal vessels. Acta Soc. Ophth. Jpn. 12: 554-555, 1908. TSUlKI, T.: Etiological considerations on the sensorineural hearing loss. Jpn. J. 0101. Tokyo 79: 1419-1552, 1976. WADA, K.: Report of Takayasu's Arteritis Research Committee, The Ministry of Health and Welfare of Japan. pp. 1- 185, 1976.
Request reprints from:
Dr. Yasuya Nomura, Department of Otolaryngology, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
ABRUPT (SHARP CUT) TYPE SENSORINEURAL HEARING LOSS -A HUMAN TEMPORAL BONE STUDYYasuya NOMURA, M.D., and Ken KITAMURA, M.D. Department of Otolaryngology, University of Tokyo Hongo, Bunkyo-ku, Tokyo, Japan
Histopathology of a case of bilateral sensorineural hearing loss of abrupt (sharp cut) type is reported. While there was a 45 dB gap in threshold between 1,000 Hz and 2,000 Hz bilaterally, the patient had a good hearing at 1,000 Hz and lower frequencies. The patient was suffering from Takayasu's arteritis. Major histopathological findings were as follows: Almost complete loss of the outer hair cells from the basal end to 12 mm area in the left cochlea (length: 30.5 mm) and 13 mm in the right (length: 31.5 mm). The inner hair cell of the same region was also missing in the left cochlea, and to a lesser degree in the right. There was a clear separation between the normal and the pathological organ of Corti. Marked loss of the cochlear neuron was noted in the same region. Blood vessels within the cochlea and the internal auditory meatus were normal. Bilateral abrupt (sharp cut) type sensorineural hearing loss with unknown etiology is a group of inner ear disease due to abiotrophy of the organ of Corti and cochlear neuron. Disposition or hereditary factor possibly plays an important role in the development of hearing loss. Bilateral sensorineural hearing loss of an abrupt type is encountered not infrequently in clinic. Both ears reveal a similar audiogram. Certain causes may be responsible for this type of audiogram, such as, ototoxic drugs and acoustic trauma. However, only abrupt type hearing loss of unknown etiology is dealt with in this paper. Onset of hearing loss is insidious. Hearing loss does not show rapid progress. Patients with this audiogram often do not recognize presence of hearing loss, particularly when hearing loss is only in higher frequencies. It is conceivable that lesions in the auditory organ might be limited, and that there must be a clear separation of the lesions from the normal area. There are several histopathological reports in which the temporal bone of abrupt type hearReceived for publication October 1, 1978 13
14
Y. NOMURA and K. KITAMURA
ing loss was mentioned in audiometric correlation. However, there are only a few papers on the bilateral abrupt type hearing loss. The purpose of this paper is to report and discuss the histopathology of the temporal bones of a case of Takayasu's arteritis who showed bilateral sensorineural hearing loss of abrupt type. CASE HISTORY
In December, 1964, a 45-year-old man was first seen at the ENT Clinic of the University of Tokyo. His chief complaint was bilateral hearing loss. He had no known history of ear diseases. In 1948, when he was 29 years of age, he had noticed that his bilateral radial pulse was not palpable. Angiographic study had 125
250
500
1000
2000
4000
8000 Hz
-10 0~------------------~-------------------4
10 20 30
40 50
60 70 80
90 dBL-__~____~____L -_ _~____~_ _~____~_ _~
Fig. 1. Audiogram and histograms of the right cochlea. The black areas represent the estimated degree of loss or degeneration of the inner hair cells, outer hair cells, cochlear neurons and stria vascularis. * Cyst in the stria vascularis.
SHARP CUT HEARING LOSS
15
revealed that his bilateral subclavian arteries were obliterated. Since then, corticosteroid had been administered under the diagnosis of Takayasu's arteritis. The patient was referred to us from medical clinic. Routine ENT check up revealed no abnormal findings except in the audiogram. The audiogram taken 4 months prior to his termination showed almost similar, bilateral abrupt (sharp cut) type hearing loss (Figs. 1 and 2). In 1969, he died of cardiac failure due to aortic insufficiency. Autopsy revealed the followings. There was dilatation of the aorta, the inner surface of which showed fine wrinkles and decrease of elasticity. Histologically, there was thickening of the adventitia, disruption of elastic tissue of the media and fibrous thickening of the intima. Marked focal lymphocytic infiltration was found. Arteries involved were: proximal portion of the pulmonary artery, the brachiocephalic trunk, the right axillary artery, the proximal portion of the right brachial artery, the left subclavian, axillary and brachial arteries, the entire length of the 125 I
-10 0 10 20 30
X_X-\
250 I
500 I
1000
2000
4000
40 50
X"
60 70
8000 Hz
-
~
x ............
X
80 90 dB
INNER HAIR CELLS
L
Fig. 2. Audiogram and histograms of the left cochlea.
16
Y. NOMURA and K. KITAMURA
bilateral common and external carotid arteries. In contrast, the internal carotid arteries were remarkably spared. The vertebral arteries were also free from pathology. Blood vessels in the cranial cavity were normal. The temporal bones were removed 5 hr postmortem by using a Schuknecht's plug cutter and fixed immediately in 10 % formalin solution. The bones were decalcified, and embedded in celloidin. Serial horizontal sections were cut at 20 micron thickness. Every tenth section was stained with hematoxylin and eosin and studied under a light microscore. FINDINGS
The external and middle ear showed no pathology in both temporal bones.
Fig. 3 Organ of Corti in the right cochlea. A : normal organ of Corti (middle turn). B: Two outer hair cells are missing (lower basal turn).
SHARP CUT HEARING LOSS
17
The right inner ear Cochlea: Extensive lesions of the organ of Corti were noted in the basal
turn. From the basal end up to 13 mm area, the outer hair cells were almost completely missing. The inner hair cells were partly present in the same area. In the remaining area of the cochlea, the outer and inner hair cells were well preserved (Figs. 1 and 3). The cochlear neurons were almost totally missing up to 9 mm area from the basal end and to a lesser degree from 9 mm to 13 mm area in the basal turn. The spiral vessel under the tunnel of Corti, vas spirale, looked normal throughout the cochlea, even in the area where the outer hair cells were missing. The stria vascularis was atrophic in the lower basal turn. There was a cyst in the stria vascularis near the apical end (Fig. 4). The external sulcus and its lining cells, and spiral prominence were normal. The inferior cochlear vein and the cochlear aqueduct were normal. Vestibule: The neuroepithelium of the macula utriculi and the cristae were essentially normal. Partial loss of neuroepithelium was observed in the anterior portion of the macula sacculi. The endolymphatic duct and sac were normal. Internal auditory meatus: The walls of the labyrinthine artery did not show any pathology. There was no pathology in the nerves within the internal auditory meatus. The left inner ear Cochlea: Findings in the organ of Corti were similar to those observed in
the right cochlea.
From the basal end up to 12 mm area the outer hair cells were
Fig. 4. Cyst in the stria vascularis (arrow). only in the apical end.
Ballooning of Reissner's membrane is noticed
18
Y. NOMURA and K. KITAMURA
almost completely missing (Fig. 2). There was marked degeneration and loss of inner hair cells. There was a decrea~ of cochlear neurons in the lower basal turn. The remaining inner and outer hair cells of the cochlea were well preserved. Atrophy of the stria vascularis was sporadic throughout the cochlea, marked in the lower basal turn and less pronounced toward the apex. The external sulcus cell and the spiral prominence were normal. Vestibule: The vestibular neuroepithelium was normal, except in the macula sacculi where loss of neuroepithelium was noted anteriorly. There was no collapse in the utricle and the saccule. The endolymphatic duct and sac were normal. Internal auditory meatus: The labyrinthine artery was normal. The nerves in the internal auditory meatus looked normal. DISCUSSION
The main pathological findings in the present case showed a marked loss of outer and inner hair cells and cochlear neurons in the continuous area of 0-13 mm from the basal end in the right cochlea and 0-12 mm in the left. These findings probably explain the abrupt type of the patient's audiogram. ODA (1973) proposed a term of "sharp cut" type hearing loss, in which patients have normal hearing in lower frequencies and abrupt hearing loss of greater than 40 dB per octave in higher frequencies. The present case showed bilateral "sharp cut" type hearing loss. In reviewing literature, lesions responsible for abrupt type hearing loss were either in the cochlea or in the eighth nerve. In their extensive study, CROWE, GUILD, and POLVOGT (1934) described that the pathology found in 33 ears with an abrupt high tone loss was not uniform. They classified histological lesions into 4 groups. Lesions in 24 ears (Group E of their classification) were most prominent in the basal turn, consisting of atrophy of the organ of Corti and nerve. Characteristic of this group, atrophy of the organ of Corti continued throughout the entire lower basal turn. Atrophy of the nerve was extensive in some cases, in others it was localized. In the area where the nerve had entirely disappeared, there was always total atrophy of the organ of Corti. In some sections with total absence of the organ of Corti, however, a few nerve fibers were seen in the osseous spiral lamina near the foramina nervosa. Transition from total absence of nerve fibers to normal nerves within the space of one millimeter or less was often seen in this group. In the organ of Corti, extensive and continuous type of atrophy was present in 10 ears, while in the remaining 14 ears atrophy was more localized or patchy. The extent of the atrophic area was not related to age. The external sulcus cells were always atrophic in the same area whether the total atrophy of the organ of Corti be extensive or localized. Often the extent of external sulcus cell atrophy was greater than that of the end organ atrophy.
SHARP CUT HEARING LOSS
19
In three ears (Group F), the organ of Corti was normal in appearance, but the nerve atrophy in the basal turn was greater than in the controls. In three ears (Group G), the organ of Corti was normal in appearance, but the nerve atrophy and the middle ear lesions were both more severe than in the controls. In four ears (Group H), the organ of Corti, nerve and middle ear changes were all within normal limits. According to GUILD (1953), a similar hearing loss resulted by sectioning a part of the cochlear nerve adjacent to the vestibular nerve. The operation was performed by Dr. Walter E. Dandy for a surgical treatment of Meniere's disease. In a study of presbycusis, SUGA and LINDSAY (1976) mentioned histopathological findings of temporal bones in nine cases who showed abrupt high tone loss. Lesions were mainly in spiral ganglion cells in four cases, one in the organ of Corti and four in both spiral ganglion cells and organ of Corti. Mild to severe thickening of the arterial wall in the internal auditory meatus and cochlea was found in the cases. However, they failed to find positive correlation between the thickening of the arterial wall and the degree and localization of lesions in the cochlea. An audiogram similar to the present case was presented in a 27-year-old female who received Kanamycin injection. Histological studies showed a severe loss of hair cells in the basalIS mm. The cochlear neurons show normal population (SCHUKNECHT, 1974). Audiometric correlations with histopathological findings were also substantiated in animal experimentation. NEFF (1947) mentioned that four out of 11 cats showed abrupt hearing loss after sectioning the auditory nerve. This was determined by utilizing the conditioned response method. In the present study, there was a clear separation between normal area and loss of sensory cells in the organ of Corti. The area of response for 1,000 Hz is more apical than 12-13 mm from the basal end of the cochleas in the present case. In this regard similar findings were mentioned by CROWE, GUILD, and POL VOGT (1934). The location of frequencies are different in literature. According to Koenig's scale (SCHUKNECHT, 1974), the location of the frequency for 1,000 Hz is 11.5 mm from the basal end in human cochlea of 31.5 mm length. Location of the frequency for 2,000 Hz is 6.9 mm from the same cochlea. BREDBERG (1968) located the area of 11 mm and 17 mm from the basal end of the cochlea responsible for the frequency of 4,000 Hz and 2,000 Hz, respectively. IGARASHI, SCHUKNECHT, and MYERS (1964) made a report on cochlear pathology of stimulation deafness on three patients, two with histories of exposure to high intensity noise and one of a head blow. Two of them showed audiogram characteristic of high frequency hearing loss, the most severe being for 4,000 Hz. Histopathology showed maximum injuries occurring in 10 to 12 mm regions. MCGILL and SCHUKNECHT (1976) reported that noise exposure induced degenera-
20
Y. NOMURA and K. KITAMURA
tive changes in 9 to 13 mm region of the cochlear duct, a maximum at 11 mm, in 6 cases. The cyst observed near the apical end of the stria vascularis was related to degenerative process. In strial presbycusis, cystic structures sometimes replace atrophied stria (SCHUKNECHT, 1974). Takayasu's arteritis (TAKAYASU, 1908) is described under various names which include pulseless disease (SHIMIZU and SANO, 1951) and the young female arteritis type of aortic arch syndrome (Ross and McKuSICK, 1953). The pathologic lesion is a panarteritis that seems to begin with inflammation of the adventitia, with subsequent disruption and fibrotic changes in the media, and marked proliferation of the intima. Although the exact etiology of this disease is unknown, it is suspected to be an autoimmune disease. 2,148 patients were seen by the Takayasu's Arteritis Research Committee, the Ministry of Health and Welfare of Japan, during the period of 1973-1975 (WADA, 1976). Among these patients, the followings were the most common complaints: vascular disturbances of extremities (72.3 %), constitutional symptoms which include fever, malaise, anorexia, weight loss, night sweats and arthralgias (66.8 %), cerebrovascular disturbances (64.6%), cardiac symptoms (55.2 %), and hypertension (45.4 %). Only one patient complained deafness. Hearing loss is not a common symptom of the disease. CURRIER, De JONG and BOLE (1954) reviewed 40 cases from literature and found three cases with deafness. The vertebral artery is usually free from the pathology, as was found in the present case. According to The Research Committee (1976), out of 89 autopsied cases only four cases, three bilateral and one unilateral, had the pathology in the wall of vertebral artery. It can be said that in the present case loss of sensory hair cell and cochlear neurons in the basal turn is responsible for the bilateral sharp cut type hearing loss. What then was the cause of such pathology? If Takayasu's arteritis is the cause, circulatory disturbance in the cochlea must be considered. The spiral vessel under the tunnel of Corti might be under circulatory disturbance. If the spiral vessel is functioning to maintain the organ or Corti, its malfunction may result in damaging the organ or Corti. However, in the present case the vessels within the cochlea and the internal auditory meatus showed no pathology. Thus, Takayasu's arteritis as the cause of the present hearing loss remains unsolved. According to TSUIKI (1976), bilateral abrupt type audiograms were found in 340 cases out of 3,481 cases with sensorineural hearing loss. Causes of the hearing loss of 340 cases were: unknown 211 (62.1 %), acoustic trauma 40 (11. 8 %), head trauma 25 (7.4%), drug intoxication 24 (7.1 %), of familial causes 20 (5.9%) and others (TSUIKI, personal communication). He also found 135 ears of abrupt type hearing loss in 458 ears (82 families) of hereditary deafness (TSUIKI, 1976). As was mentioned by LANGENBECK (1936), disposition of the individual is important
SHARP CUT HEARlNG LOSS
21
for the development of sensorineural hearing loss, similar III both ears (Symmetriegesetz). Histopathology of the bilateral sensorineural hearing loss of abrupt type, symmetrical in audiogram, of unknown etiology were only reported in eight cases (CROWE et al., 1934). Histological characteristics were marked loss of cochlear neuron and atrophy of the organ of Corti or loss of sensory hair cells in the basal turn. Disposition or hereditary factors could play an important role for the pathogenesis of abiotrophic hearing loss. REFERENCES BREDBERG, G.: Cellular pattern and nerve supply of the human organ of Corti. Acla Otolaryngol. Suppl. 236: 1-135, 1968. CROWE, S. J., GUILD, S. R., and POLYOGT, L. M.: Observations on the pathology of high-tone deafness. Bull. Johns Hopkins Hosp. 54: 315-379, 1934. CURRIER, R. D., De JONG, R. M., and BOLE, G. G.: Pulseless disease, central nervous system manifestations. Neurology 4: 818-830, 1954. GUILD, S. R.: The effects on hearing of partial sections of the cochlear nerve in man. Acta Ololaryngol. 43 : 199-207, 1953. IGARASHI, M., SCHUKNECHT, H. F., and MYERS, E. N.: Cochlear pathology in humans with stimulation deafness. J . Laryngol. 0101. 78: 115-123, 1964. LANGENBECK, B. : Das Symmetriegesetz der erblichen Taubheit. Z. Hals-usw. Heilk. 39 : 223261, 1936. MCGILL, T.J.!', and SCHUKNECHT, H. F.: Human cochlear changes in noise induced hearing loss. Laryngoscope 86: 1293-1302, 1976. NEFF, W. D.: The effects of partial section of the auditory nerve. J. Compa. Physiol. Psychiat. 40: 203-215, 1947. ODA, M.: Clinical studies of sharp cut type sensorineural hearing loss. Jpn. J. Otol. Tokyo 76 : 42-58, 1973. Pathology of TAKAYASU'S arteritis. Takayasu's Arteritis Research Committee, The Ministry of Health and Welfare of Japan. pp. 1-116, 1976. Ross, R . S., and McKuslcK, V. A.: Aortic arch syndromes, diminished or absent pulses in arteries arising from arch of aorta. Arch. Int. Med. 92: 701-740, 1953. SCHUKNECHT, H. F.: Pathology of the Ear. Harvard University Press, Cambridge, MA., 1974. SHIMIZU, K., and SAND, K . : Pulseless disease. J. Neuropathol. Clin. Neurol. 1: 37, 1951. SUGA, F., and LINDSAY, J. R . : Histopathological observations of presbycusis. Ann. DIal. 85: 169-184, 1976. TAKAYASU, M.: A case with peculiar changes of the central retinal vessels. Acta Soc. Ophth. Jpn. 12: 554-555, 1908. TSUlKI, T.: Etiological considerations on the sensorineural hearing loss. Jpn. J. 0101. Tokyo 79: 1419-1552, 1976. WADA, K.: Report of Takayasu's Arteritis Research Committee, The Ministry of Health and Welfare of Japan. pp. 1- 185, 1976.
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Dr. Yasuya Nomura, Department of Otolaryngology, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan