Ann Otol Rhinol Laryngol99: 1990
CORRELATION BETWEEN MASTOID PNEUMATIZATION AND POSITION OF THE LATERAL SINUS ANAT SHATZ,
MD
JACOB
SADE, MD
KFAR SABA, ISRAEL
The distance between the lateral sinus and the external ear canal was measured in 148 patients (150 ears) with completely sclerotic (nonpneumatized) mastoids and in 75 healthy random control subjects (150 ears) with pneumatized mastoids. A highly significant difference (p< .0001) was found between the two groups, the mean distance (:l:SD) among patients being 7.8:1:1.7 mm, while among controls it was 13.5:1:2.8 mm. Moreover, a significant positive correlation (p< .001) was found within the pneumatized control group itself, between the sinus' distance and the degree of mastoid pneumatization. The results of this study may be interpreted by those who espouse environmental theories as denoting that infantile otitis media will determine the position of the lateral sinus. However, those who favor the genetic explanation may maintain that since the position of the sinus is established prenatally and involves organogenetically the shape of the skull, the final position is unlikely to be influenced by postnatal otitis media. KEY WORDS - lateral sinus, pneumatized mastoid, sclerotic mastoid.
cholesteatoma (120 ears or 80%). The problem of the other ear or symmetry of pneumatization in the presence of a sclerotic mastoid will be the subject of a separate communication.
INTRODUCTION
The question of the factors that influence the extent of mastoid pneumatization, ie, the postinflammatory (environmental) influence versus a genetic factor, has been disputed for years."? In our previous study we have shown a link between otosclerosis, a hereditary disease, and the size of mastoid pneumatization. Another avenue to approach this question could be found by correlating the degree of pneumatization with a well-defined anatomic structure in the temporal bone that is unlikely to be influenced by postnatal (inflammatory) events. Such a structure could be found in the lateral sinus, which on the one hand is the main posterior border of the mastoid process, and on the other is also part and parcel of the entire skull framework. While it is a common clinical observation that the distance of the lateral sinus from the external ear canal is relatively short in mastoids that are poorly pneumatized, measurements of this observation are so far missing. The purpose of this study was to quantify and to look for a correlation between the amount of mastoid pneumatization and the distance of the lateral sinus from the external ear canal.
The age range of the two groups was 18 to 70 years, ie, ages far beyond the final stage of pneumatization development." The sex distribution was about equal in both groups, ie, 49:51 (M/F) for normals and 47:53 (M/F) for sclerotics. METHODS
The position of the lateral sinus was defined as the shortest distance from its anterior border to the posterior border of the external auditory canal, as seen on radiographs taken in the Schuller lateral projection. The posterior border of the ear canal, the anterior border of the lateral sinus, and the outer limits of the air cell system were marked on the x-ray films and transferred to transparent millimetric paper. Measurements of the pneumatized areas were performed directly by computerized planimetry. A Hewlett Packard 9111-A digitizer, operated in conjunction with a Hewlett Packard 9817-H computer, was used as described in detail in our previous study. 4
MATERIAL
The extent of mastoid pneumatization and the posterior position of the lateral sinus were examined in two groups. Group 1 consisted of 150 randomized healthy ears of 75 volunteers having no history of ear disease. All 150 ears showed normal eardrums on microscopic otoscopy and produced a normal audiogram. Group 2 consisted of 150 ears of 148 patients with completely sclerotic mastoids, retrieved from a patient population suffering from either simple chronic otitis media (30 ears or 20 %) or from
RESULTS
Distance of Lateral Sinus From Posterior Wall of External Ear Canal. In group 1, the mean distance ± SD measured for the 150 normal ears was 13.5:±: 2.8 mm (range, 8 to 22 mm) (Fig lA). In group 2, the mean distance ± SD for the sclerotic mastoids was 7.8 ± 1.7 mm (range, 7 to 11 mm) (Fig IB). There is a 42 % difference between the means of the two groups, which is statistically highly significant
From the Department of Otolaryngology, Meir General Hospital, Kfar Saba, and the Sadder School of Medicine, Tel Aviv University, Israel. Jacob Sade, MD, Dept of Otolaryngology, Meir General Hospital, Kfar Saba 44281, Israel.
CORRESPONDENCE -
142
Shatz & Sade, Mastoid Pneumatization & Lateral Sinus
143
Fig 1. Radiographs showing distance of lateral sinus from external ear canal (arrows) in A) pneumatized mastoid and B) sclerotic mastoid. C - condyle of mandible.
(t test, p< .0001) and is also evident from the distribution of the distance within the two groups as demonstrated in Fig 2. Correlation Between Extent oj Mastoid Pneumatization and Distance oj Lateral Sinus. When pneumatization was present, as it was in all the normal subjects, a correlation between the distance of the lateral sinus and the cross-sectional area of the mastoid pneumatization was looked for. Figure 3 presents this correlation, which is highly significant (r = 0.474, p< .001) and shows that the larger the pneumatization, the further the lateral sinus from
o empty bors=
7C
sclerotic mastoids • filled borsnon sclerotic mastoids
60
-
50
-
(f)
Q)
c:
.8 40t1::J
Q
~
E
3Ot-
o o 20t-
-
o~
-
'+-
c
I.
Fig 2. Distribution of distance of lateral sinus in normally pneumatized mastoids and sclerotic mastoids.
the external ear canal. Because of the great symmetry of mastoid pneumatization in the healthy group, statistical evaluation was performed as follows: 1) taking all 150 ears into account, 2) taking only the 75 right ears, and 3) taking only the 75 left ears. No differences were found among these groups. DISCUSSION
The present study confirms that the lateral sinus does not traverse the mastoid process in a fixed position. The variable course of the lateral sinus has been recognized previously by several authors." Meltzer? as well as Tumarkin" studied in great detail the interrelationship between pneumatization and the lateral sinus from a surgical point of view. While no measurements as to the relationship of pneumatization to the position of the lateral sinus have been reported previously, most experienced otologists' gained the surgical impression that reduced pneumatization is related to a lateral sinus that lies far "forward," ie, close to the posterior wall of the external auditory canal. Virapongse et al,lO who actually studied the relationship of the pneumatization to Korners' septum, could not find any correlation between these features . Our present study adds two quantitative findings: 1) the existence of a significant relationship between the degree of mastoid pneumatization, in pneumatized mastoids, and the distance of the lateral sinus from the posterior border of the external ear canal; and 2) a consistent significant difference between nonpneumatized (sclerotic) mastoids on the one hand and pneumatized mastoids on the other, regarding the distance of the lateral sinus from the posterior border of the external ear canal.
As pointed out in the Introduction, the environmental versus the genetic influence on the size of the mastoid pneumatization has been disputed for years - proponents ~f ~nvironmental theories being usually 10 the majority.':" The results of the present
144
Shatz & Sade, Mastoid Pneumatization & Lateral Sinus 3
NORMAL EARS
E
U
w
u
z a:
~
Ul H
1:1
o'+---__----T---t----_----t--! o 6 12 18 24 30 MASTOID AIR CELL AREA (cm 2
)
Fig 3. Correlation between distance of lateral sinus and cross-sectional area of pneumatized mastoids.
study can be interpreted by either school as proving its point. The environmentalists may see in early middle ear inflammatory disease a potent enough force to inhibit the development of the mastoid pneumatization and thereby to influence the position and place of the sigmoid sinus. The other school may, however, maintain that the sigmoid sinus is an organ whose structure is too big to be influenced by postnatal factors such as an inflammation - which usually occurs after the position of the major body already has been determined. While the mastoid air cell system develops only after birth, the lateral sinus develops from the primary head veins, whose position in the temporal bone already is established by the seventh week of embryonal life. l1 • 11 Furthermore, should any postnatal events such as otitis in childhood be considered to affect the position of the lateral sinus, this would be tantamount to assuming that such an inflammation will affect the shape of the skull at a relatively late stage, as the sinus is a major structure on which the shape of most other bony parts of the skull depends (Fig 4). An exception to this could be a situation in which an inflammation of the middle ear, during the second or third year, would alter only the course of the mastoid segment of the lateral sinus. However, this latter situation is probably not the case, as is seen from the smooth course (presenting no kinks) the entire lateral sinus runs, in sclerotic as well as in pneumatized mastoids (Fig 1). Our previous study" showed a highly significant
Fig 4. Base of skull from above showing lateral sinus (painted dark) as one of main structures traversing base of skull.
(p< .0001) link between otosclerosis - a genetic disorder - and the degree of pneumatization. If the findings of the present study are interpreted as evidence of a genetic influence on the degree of pneumatization, one should take into account a complex heterogenous situation. Otosclerosis is considered to be due to a simple mutant gene," while the position of the lateral sinus probably is influenced by more than one gene, in accordance with the polygenetic theory of inheritance. 14 It should be pointed out that while these findings possibly may support the notion that the degree of mastoid pneumatization also has a genetic basis, they do not exclude the possibility that postnatal events also may influence the pneumatization process and determine its final degree. It is interesting that in the dispute between the nature (genetic) and nurture (environment, ie, inflammation) schools the supporters of either opinion have not considered the possibility that the two are not mutually exclusive. Our present study did not include a possible intermediate group, the so-called diploic mastoid, which might form a link between the pneumatized and sclerotic mastoids whereby genetic determinants and postnatal influences might play a role concomitantly. This will be the subject of a separate communication.
ACKNOWLEDGMENTS - The authors thank Professor A. Adam from the GeneticsDepartment, Open University, Tel Aviv,for offeringhelpful advice on the genetic aspectsof this study; 1. Gelenter from the Department of Statistics,Tel AvivUniversity, for assistance In statistical analysis; and Professor Jorgen Holmquist from the Universityof GOteborg, Sweden, for the fruitful discussions that finally led to this study.
REFERENCES 1. Diamant M. Otitis and pneumatization of the mastoid bone. Lund, Sweden: Hakan, Ohlssons Boktrycken, 1940. 2. Wittmack K. Uber die norm ale und die pathologische Pneumatisation des SchliHenbeines einschliesslich ihrer Beziehungen zu der Mittelohrenkrankungen. Jena: Gustav Fischer, 1918.
3. Tos M, Stangerup SE, Harid G. Mastoid pneumatization: evidence of environmental theory. Arch Otolaryngol 1984;110: 502-7. 4. Sade J, Shatz A, Kremer S, Levit 1. Mastoid pneumatization in otosclerosis. Ann Otol Rhinol Laryngol 1989;98:451-
4.
Shatz & Sade, Mastoid Pneumatization & Lateral Sinus 5. Eby TL, Nadol JB. Postnatal growth of the human temporal bone. Implications for cochlear implants in children. Ann Otol Rhinol LaryngoI1986;95:356-64. 6. Graham MD. The jugular bulb. Its anatomic and clinical considerations in contemporary otology. Laryngoscope 1977; 87:1-20.
145
1939:105-204. 10. Virapongse C, Sarwar M, Bhimani S, Sasaki C, Shapiro R. Computed tomography of temporal bone pneumatization. AJNR 1985;6:561-8.
H. Butler H. Development of mammalian dural venous sinuses. J Anat 1967;102:33-56.
7. Meltzer PE. The mastoid cells. Their arrangement in relation to the sigmoid portion of the transverse sinus. Arch OtolaryngoI1934;19:327-35.
12. Butler H. The development of certain human dural venous sinuses. J Anat 1957;91:510-26.
8. Tumarkin A. On the nature and significance of hypocellularity of the mastoid. J Laryngol OtoI1959;73:34-41.
13. McKusik VA. Mendelian inheritance in man. 7th ed. Baltimore: Johns Hopkins University Press, 1986:399.
9. Fowler EP Jr. Diseasesofthe middle ear. In: Fowler EP Jr, ed. Medicine of the ear. New York: Thomas Nelson and Sons,
14. Stern C. Principles of human genetics. 3rd ed. San Francisco: WH Freeman and Co, 1973:443-67.
FIFTH INTERNATIONAL SYMPOSIUM RECENT ADVANCES IN OTITIS MEDIA The Fifth International Symposium on Recent Advances in Otitis Media will be held May 20-23, 1991, at the Sheraton Bal Harbour in Bal Harbour, Florida. For further information, contact David J. Lim, MD, 4331 University Hospitals Clinic, 456 W Tenth Avenue, Columbus, OH 43210; Phone: (614) 293-8103; Fax: (614) 293-5506.
CALL FOR POSTER ABSTRACTS GENETICS OF HEARING IMPAIRMENT SYMPOSIUM The Genetics of Hearing Impairment Symposium will be held September 24-26, 1990, in New York City. Abstracts for posters are solicited in genetic determinates of normal hearing, gene mapping, registries, carrier features, animal models, developmental studies, transgenetic models, genetic susceptibility, and other aspects of the genetics of hearing impairment. Abstracts for posters are due May 1, 1990 and should not exceed 300 words. Extended abstracts for posters will be required for publication. Send abstracts for posters to Robert J. Ruben, MD, Chairman, Department of Otolaryngology, Montefiore Medical Center, HI East 210th Street, VCA 4, Bronx, NY 10467-2490; (212) 734-5368.
CORRELATION BETWEEN MASTOID PNEUMATIZATION AND POSITION OF THE LATERAL SINUS ANAT SHATZ,
MD
JACOB
SADE, MD
KFAR SABA, ISRAEL
The distance between the lateral sinus and the external ear canal was measured in 148 patients (150 ears) with completely sclerotic (nonpneumatized) mastoids and in 75 healthy random control subjects (150 ears) with pneumatized mastoids. A highly significant difference (p< .0001) was found between the two groups, the mean distance (:l:SD) among patients being 7.8:1:1.7 mm, while among controls it was 13.5:1:2.8 mm. Moreover, a significant positive correlation (p< .001) was found within the pneumatized control group itself, between the sinus' distance and the degree of mastoid pneumatization. The results of this study may be interpreted by those who espouse environmental theories as denoting that infantile otitis media will determine the position of the lateral sinus. However, those who favor the genetic explanation may maintain that since the position of the sinus is established prenatally and involves organogenetically the shape of the skull, the final position is unlikely to be influenced by postnatal otitis media. KEY WORDS - lateral sinus, pneumatized mastoid, sclerotic mastoid.
cholesteatoma (120 ears or 80%). The problem of the other ear or symmetry of pneumatization in the presence of a sclerotic mastoid will be the subject of a separate communication.
INTRODUCTION
The question of the factors that influence the extent of mastoid pneumatization, ie, the postinflammatory (environmental) influence versus a genetic factor, has been disputed for years."? In our previous study we have shown a link between otosclerosis, a hereditary disease, and the size of mastoid pneumatization. Another avenue to approach this question could be found by correlating the degree of pneumatization with a well-defined anatomic structure in the temporal bone that is unlikely to be influenced by postnatal (inflammatory) events. Such a structure could be found in the lateral sinus, which on the one hand is the main posterior border of the mastoid process, and on the other is also part and parcel of the entire skull framework. While it is a common clinical observation that the distance of the lateral sinus from the external ear canal is relatively short in mastoids that are poorly pneumatized, measurements of this observation are so far missing. The purpose of this study was to quantify and to look for a correlation between the amount of mastoid pneumatization and the distance of the lateral sinus from the external ear canal.
The age range of the two groups was 18 to 70 years, ie, ages far beyond the final stage of pneumatization development." The sex distribution was about equal in both groups, ie, 49:51 (M/F) for normals and 47:53 (M/F) for sclerotics. METHODS
The position of the lateral sinus was defined as the shortest distance from its anterior border to the posterior border of the external auditory canal, as seen on radiographs taken in the Schuller lateral projection. The posterior border of the ear canal, the anterior border of the lateral sinus, and the outer limits of the air cell system were marked on the x-ray films and transferred to transparent millimetric paper. Measurements of the pneumatized areas were performed directly by computerized planimetry. A Hewlett Packard 9111-A digitizer, operated in conjunction with a Hewlett Packard 9817-H computer, was used as described in detail in our previous study. 4
MATERIAL
The extent of mastoid pneumatization and the posterior position of the lateral sinus were examined in two groups. Group 1 consisted of 150 randomized healthy ears of 75 volunteers having no history of ear disease. All 150 ears showed normal eardrums on microscopic otoscopy and produced a normal audiogram. Group 2 consisted of 150 ears of 148 patients with completely sclerotic mastoids, retrieved from a patient population suffering from either simple chronic otitis media (30 ears or 20 %) or from
RESULTS
Distance of Lateral Sinus From Posterior Wall of External Ear Canal. In group 1, the mean distance ± SD measured for the 150 normal ears was 13.5:±: 2.8 mm (range, 8 to 22 mm) (Fig lA). In group 2, the mean distance ± SD for the sclerotic mastoids was 7.8 ± 1.7 mm (range, 7 to 11 mm) (Fig IB). There is a 42 % difference between the means of the two groups, which is statistically highly significant
From the Department of Otolaryngology, Meir General Hospital, Kfar Saba, and the Sadder School of Medicine, Tel Aviv University, Israel. Jacob Sade, MD, Dept of Otolaryngology, Meir General Hospital, Kfar Saba 44281, Israel.
CORRESPONDENCE -
142
Shatz & Sade, Mastoid Pneumatization & Lateral Sinus
143
Fig 1. Radiographs showing distance of lateral sinus from external ear canal (arrows) in A) pneumatized mastoid and B) sclerotic mastoid. C - condyle of mandible.
(t test, p< .0001) and is also evident from the distribution of the distance within the two groups as demonstrated in Fig 2. Correlation Between Extent oj Mastoid Pneumatization and Distance oj Lateral Sinus. When pneumatization was present, as it was in all the normal subjects, a correlation between the distance of the lateral sinus and the cross-sectional area of the mastoid pneumatization was looked for. Figure 3 presents this correlation, which is highly significant (r = 0.474, p< .001) and shows that the larger the pneumatization, the further the lateral sinus from
o empty bors=
7C
sclerotic mastoids • filled borsnon sclerotic mastoids
60
-
50
-
(f)
Q)
c:
.8 40t1::J
Q
~
E
3Ot-
o o 20t-
-
o~
-
'+-
c
I.
Fig 2. Distribution of distance of lateral sinus in normally pneumatized mastoids and sclerotic mastoids.
the external ear canal. Because of the great symmetry of mastoid pneumatization in the healthy group, statistical evaluation was performed as follows: 1) taking all 150 ears into account, 2) taking only the 75 right ears, and 3) taking only the 75 left ears. No differences were found among these groups. DISCUSSION
The present study confirms that the lateral sinus does not traverse the mastoid process in a fixed position. The variable course of the lateral sinus has been recognized previously by several authors." Meltzer? as well as Tumarkin" studied in great detail the interrelationship between pneumatization and the lateral sinus from a surgical point of view. While no measurements as to the relationship of pneumatization to the position of the lateral sinus have been reported previously, most experienced otologists' gained the surgical impression that reduced pneumatization is related to a lateral sinus that lies far "forward," ie, close to the posterior wall of the external auditory canal. Virapongse et al,lO who actually studied the relationship of the pneumatization to Korners' septum, could not find any correlation between these features . Our present study adds two quantitative findings: 1) the existence of a significant relationship between the degree of mastoid pneumatization, in pneumatized mastoids, and the distance of the lateral sinus from the posterior border of the external ear canal; and 2) a consistent significant difference between nonpneumatized (sclerotic) mastoids on the one hand and pneumatized mastoids on the other, regarding the distance of the lateral sinus from the posterior border of the external ear canal.
As pointed out in the Introduction, the environmental versus the genetic influence on the size of the mastoid pneumatization has been disputed for years - proponents ~f ~nvironmental theories being usually 10 the majority.':" The results of the present
144
Shatz & Sade, Mastoid Pneumatization & Lateral Sinus 3
NORMAL EARS
E
U
w
u
z a:
~
Ul H
1:1
o'+---__----T---t----_----t--! o 6 12 18 24 30 MASTOID AIR CELL AREA (cm 2
)
Fig 3. Correlation between distance of lateral sinus and cross-sectional area of pneumatized mastoids.
study can be interpreted by either school as proving its point. The environmentalists may see in early middle ear inflammatory disease a potent enough force to inhibit the development of the mastoid pneumatization and thereby to influence the position and place of the sigmoid sinus. The other school may, however, maintain that the sigmoid sinus is an organ whose structure is too big to be influenced by postnatal factors such as an inflammation - which usually occurs after the position of the major body already has been determined. While the mastoid air cell system develops only after birth, the lateral sinus develops from the primary head veins, whose position in the temporal bone already is established by the seventh week of embryonal life. l1 • 11 Furthermore, should any postnatal events such as otitis in childhood be considered to affect the position of the lateral sinus, this would be tantamount to assuming that such an inflammation will affect the shape of the skull at a relatively late stage, as the sinus is a major structure on which the shape of most other bony parts of the skull depends (Fig 4). An exception to this could be a situation in which an inflammation of the middle ear, during the second or third year, would alter only the course of the mastoid segment of the lateral sinus. However, this latter situation is probably not the case, as is seen from the smooth course (presenting no kinks) the entire lateral sinus runs, in sclerotic as well as in pneumatized mastoids (Fig 1). Our previous study" showed a highly significant
Fig 4. Base of skull from above showing lateral sinus (painted dark) as one of main structures traversing base of skull.
(p< .0001) link between otosclerosis - a genetic disorder - and the degree of pneumatization. If the findings of the present study are interpreted as evidence of a genetic influence on the degree of pneumatization, one should take into account a complex heterogenous situation. Otosclerosis is considered to be due to a simple mutant gene," while the position of the lateral sinus probably is influenced by more than one gene, in accordance with the polygenetic theory of inheritance. 14 It should be pointed out that while these findings possibly may support the notion that the degree of mastoid pneumatization also has a genetic basis, they do not exclude the possibility that postnatal events also may influence the pneumatization process and determine its final degree. It is interesting that in the dispute between the nature (genetic) and nurture (environment, ie, inflammation) schools the supporters of either opinion have not considered the possibility that the two are not mutually exclusive. Our present study did not include a possible intermediate group, the so-called diploic mastoid, which might form a link between the pneumatized and sclerotic mastoids whereby genetic determinants and postnatal influences might play a role concomitantly. This will be the subject of a separate communication.
ACKNOWLEDGMENTS - The authors thank Professor A. Adam from the GeneticsDepartment, Open University, Tel Aviv,for offeringhelpful advice on the genetic aspectsof this study; 1. Gelenter from the Department of Statistics,Tel AvivUniversity, for assistance In statistical analysis; and Professor Jorgen Holmquist from the Universityof GOteborg, Sweden, for the fruitful discussions that finally led to this study.
REFERENCES 1. Diamant M. Otitis and pneumatization of the mastoid bone. Lund, Sweden: Hakan, Ohlssons Boktrycken, 1940. 2. Wittmack K. Uber die norm ale und die pathologische Pneumatisation des SchliHenbeines einschliesslich ihrer Beziehungen zu der Mittelohrenkrankungen. Jena: Gustav Fischer, 1918.
3. Tos M, Stangerup SE, Harid G. Mastoid pneumatization: evidence of environmental theory. Arch Otolaryngol 1984;110: 502-7. 4. Sade J, Shatz A, Kremer S, Levit 1. Mastoid pneumatization in otosclerosis. Ann Otol Rhinol Laryngol 1989;98:451-
4.
Shatz & Sade, Mastoid Pneumatization & Lateral Sinus 5. Eby TL, Nadol JB. Postnatal growth of the human temporal bone. Implications for cochlear implants in children. Ann Otol Rhinol LaryngoI1986;95:356-64. 6. Graham MD. The jugular bulb. Its anatomic and clinical considerations in contemporary otology. Laryngoscope 1977; 87:1-20.
145
1939:105-204. 10. Virapongse C, Sarwar M, Bhimani S, Sasaki C, Shapiro R. Computed tomography of temporal bone pneumatization. AJNR 1985;6:561-8.
H. Butler H. Development of mammalian dural venous sinuses. J Anat 1967;102:33-56.
7. Meltzer PE. The mastoid cells. Their arrangement in relation to the sigmoid portion of the transverse sinus. Arch OtolaryngoI1934;19:327-35.
12. Butler H. The development of certain human dural venous sinuses. J Anat 1957;91:510-26.
8. Tumarkin A. On the nature and significance of hypocellularity of the mastoid. J Laryngol OtoI1959;73:34-41.
13. McKusik VA. Mendelian inheritance in man. 7th ed. Baltimore: Johns Hopkins University Press, 1986:399.
9. Fowler EP Jr. Diseasesofthe middle ear. In: Fowler EP Jr, ed. Medicine of the ear. New York: Thomas Nelson and Sons,
14. Stern C. Principles of human genetics. 3rd ed. San Francisco: WH Freeman and Co, 1973:443-67.
FIFTH INTERNATIONAL SYMPOSIUM RECENT ADVANCES IN OTITIS MEDIA The Fifth International Symposium on Recent Advances in Otitis Media will be held May 20-23, 1991, at the Sheraton Bal Harbour in Bal Harbour, Florida. For further information, contact David J. Lim, MD, 4331 University Hospitals Clinic, 456 W Tenth Avenue, Columbus, OH 43210; Phone: (614) 293-8103; Fax: (614) 293-5506.
CALL FOR POSTER ABSTRACTS GENETICS OF HEARING IMPAIRMENT SYMPOSIUM The Genetics of Hearing Impairment Symposium will be held September 24-26, 1990, in New York City. Abstracts for posters are solicited in genetic determinates of normal hearing, gene mapping, registries, carrier features, animal models, developmental studies, transgenetic models, genetic susceptibility, and other aspects of the genetics of hearing impairment. Abstracts for posters are due May 1, 1990 and should not exceed 300 words. Extended abstracts for posters will be required for publication. Send abstracts for posters to Robert J. Ruben, MD, Chairman, Department of Otolaryngology, Montefiore Medical Center, HI East 210th Street, VCA 4, Bronx, NY 10467-2490; (212) 734-5368.
