Otology and Neurotology
Prevalence of Hearina Loss in Adults with Sickle Cell Disease Margie R. Crawford; Herbert Jay Gould, PhD; Wally R. Smith, MD; Neal Beckford, MD; Willie Ruth Gibson; Loretta Bobo, MD Memphis State University, Memphis, Tennessee (M.R.C., H.J.G.) and University of Tennessee, Memphis, Tennessee (W. R.S., N.B., W.R.G., L.B.)
ABSTRACT Hearing status in 75 adult subjects with sickle cell disease was examined. Thirty-one (or 41%) of the subjects failed the hearing screening. When examined by hemoglobin type, it was found that persons with sickle cell C disease had the greatest incidence of hearing loss, although all subject groups exhibited greater prevalence rates than the general population. The results suggest that routine audiologic assessment be incorporated into the regular medical examination for adults with sickle cell disease (Ear Hear 12 5349-351).
SICKLE CELL ANEMIA was first documented as an abnormal blood condition characterized by sickleshaped cells (Hemck, 1910). The term “sickle cell disease” is used to encompass sickle cell anemia (HbSS) and sickle cell variants, such as sickle cell C disease (HbSC) and the sickle cell thalassemias (HbSB-thal). The disease is transmitted in a Mendelian fashion (Orchick & Dunn, 1977; Scott, 1986). Sickle cell trait (HbAS), not a form of the disease, occurs when one has the heterozygous state, representing the simultaneous occurrence of the sickle cell gene and the gene responsible for other hemoglobins (Freidman, Luban, Herer, & Williams, 1980; Scott, 1986). The major characteristics of sickle cell disease are hemolytic anemia, increased susceptibility to life threatening infections, and painful vaso-occlusive crises (Freidman et al, 1980). There is also chronic organ damage from regional ischemia and necrosis. Although there are no hematologic markers of impending painful crises, patients with HbSC and HbSB-thal have higher hematocrits and less severe complications than do patients with the HbSS form of the disease. Also, patients with higher percentages of hemoglobin F (HbF, fetal hemoglobin) and a higher number of alpha genes have less severe disease (Charache, Lubin, & Reid, 1984). Ear and Hearing, Vol. 12, No. 5,1991
The description and incidence of communication disorders for the sickle cell disease population is unknown (Berry, 1975). Sickle cell disease, by its very nature, suggests the potential for involvement throughout the entire neurologic system (Sharp & Orchick, 1977). Several attempts have been made to characterize the impact of sickle cell disease in the auditory system. Tissue changes associated with hypoxia and ischemia of inner ear structures were observed in the temporal bone of a patient who succumbed to a sickle cell crisis (Morganstein & Manace, 1969). Individuals with sickle cell disease have demonstrated reversible hearing loss over a 3 mo period (Orchick & Dunn, 1977; Urban, 1973). Several researchers have investigated the relationship between sickle cell disease and auditory dysfunction (Berry, 1973; Freidman et al, 1980; Sharp & Orchick, 1978). Berry (1973) observed no definitive pattern of hearing loss or abnormality. However, inconsistencies were observed across audiologic tests. Sharp and Orchick ( 1977)reported that peripheral hearing sensitivity was not significantly affected by the disease. However, time-compressed speech scores suggested that persons with sickle cell anemia may have impaired or reduced central auditory function. Freidman et a1 (1980) observed that the incidence of hearing loss was higher for the sickle cell anemia population than the general population. They concluded that the presence of any hearing loss in HbSS patients, even though it is of a mild degree, may reflect those patients with more serious complications arising from the disease. The largest study of hearing loss and sickle cell disease was performed on 83 adults with HbSS in the West Indies (Todd, Serjeant, & Larson, 1973). Todd et a1 ( 1973)found a deficit in hearing in 18 out of 83 patients (22%). However, they were unable to determine etiologic factors for the loss. These studies suggest that the prevalence of hearing loss among persons with sickle cell disease is greater than that of the general population. The purpose of this investigation was to determine the prevalence of hearing loss in a group of adults with sickle cell disease. In addition, the possible relationship between type of sickle cell disease, hematocrit levels and presence of hearing loss was investigated.
-
0196/0202/91/1205-0349$03.00/0 ‘ EARAND HEARING Copyright Q 1991 by Williams 8 Wilkins Printed in the U.S.A.
Hearing Loss in Sickle Cell Disease
349
hemoglobin type. When examined in this manner, subjects with HbSC exhibited the highest prevalence rate [9 out of 13 (69%) subjects]. HbSB+-thal subjects exhibited a prevalence of 50%, whereas subjects with HbSS had a 36% prevalence. Chi-square analysis of these three groups revealed that subjects with HbSC disease had a significantly greater prevalence of hearing loss ( p < 0.05, Table 2). Among hemoglobin types there were no statistically significant differences of hematocrit levels, percent HbF, or gender. The hearing loss subject group had a significantly higher mean age than the normal-hearing group (34 to 28 yr, p c 0.05, Student's t-test).
METHODS
Subjects (42 female and 33 male) were patients at the DigsKraus Sickle Cell Center at the Regional Medical Center (Memphis, TN). Patients ranged in age from 18 to 58 yr. with a mean age of 3 1 yr. Subjects were categorized by hemoglobin type (Table 1), determined by hemoglobin electrophoresis. The hearing status and hematocrit were assessed during a regular medical examination. Patients were free from crises and were not hospitalized for at least 1 mo before data collection. Percent HbF determinations were done by the alkali denaturation technique of Singer (Singer, 195 1). Bilateral hearing status was assessed in a nonsound-treated room measured for ambient noise (ANSI S3.1, 1977; standard for Criteria for Permissible Noise During Audiometric Testing). A portable audiometer (Maico MA27) was used to assess hearing. The patients were classified as having normal hearing or a hearing loss. The hearing loss group consisted of subjects with thresholds worse than 25 dB HL at 1000 through 8000 Hz and worse than 30 dBHL at 250 and 500 Hz for two or more frequencies for at least one ear. The looser criteria, at 250 and 500 Hz, were based on the ambient noise measures made. The nonloss group consisted of all remaining subjects. Statistical analysis was done by Student's I-test and Chi-square analysis for categorical data, and by Fisher's exact test when categories contained fewer than five members.
DISCUSSION
The results of this investigation suggest that the prevalence of hearing loss in adults with sickle cell disease, at 4 1 %, is greater than the general population. Demographic data show that approximately 7.2% of African Americans below 64 yr exhibit some type of hearing impairment (Hotchkiss, 1989). The cochlea is highly susceptible to disruption of blood flow, as it is supplied by a terminal artery. Any disruption in the normal blood supply, as occurs during vaso-occlusive crises, will result in reduced oxygen supply to cochlear structures (Kimura & Perlman, 1958). Interestingly, the present investigation found a much higher prevalence of hearing loss in adults with HbSC disease. An explanation for this finding might be the higher blood viscosity, possibly related to higher hematocrits in persons with HbSC disease. Further research is required to explain this phenomenon. Patients with HbSC disease typically do have more retinopathy, perhaps a parallel phenomenon related to blood viscosity. Although there was no significant difference between mean hematocrits for the hearing loss versus nonloss groups, there was an age difference between these two groups (34 versus 28 yr). These differences can be
RESULTS
There were 50 subjects with HbSS. The second group, 13, was comprised of subjects with HbSC. Eight subjects had HbSB+-thal, whereas the four remaining subjects had HbSBO-thal. Prevalence of hearing loss was determined by subject number, not by number of ears. A total of 31 subjects (41%) were classified as exhibiting hearing loss. Eighteen subjects came from the HbSS group. Nine subjects had HbSC disease and four had HbSB+-thal. None of the subjects with HbSBO-thal were found to have hearing loss. Prevalence of hearing loss was also examined by Table 1. Prevalence of hearing loss for sickle cell disease subjects N
N with Hearing Loss
YO Hearing Loss by
Hemoglobin Type Sickle cell anemia (HbSS) Sickle cell C disease (HbSC) Sickle cell-thalassemia disease (HbSP+-thal) Sickle cell-thalassemia disease (HbSBO-thal)
50 13 8 4
18 9 4 0
36% 69% 50%
Total
75
31
Hemoglobin Type
Table 2. Chi-square analysis by hemoglobin type Hemoglobin Type
Value
Probability
Sickle cell anemia (HbSS) Sickle cell C disease (HbSC) Sickle cell-thalassemia disease (HbSP+-thal) Sickle cell-thalassemia disease (HbSPo-thaI)
1.94 5.25 0.31 2.90
0.16 0.02' 0.58
0.08
Fisher's Exact Test 0.22
0.OP 0.70 0.14
* Significant at the 0.05 level. ~
350
Crawford el al
~~~~
Ear and Hearing, Vol. 12, No. 5,1991
explained by prolonged exposure to repeated or continued ischemia as a factor for increased susceptibility to hearing loss. These findings suggest the need for routine audiologic assessment for adults with sickle cell disease. It is likely that a number of patients will benefit from amplification, management, and counseling of hearing loss. In summary, 41 ?6 of the subjects in this study exhibited hearing loss. Our findings suggest that persons with sickle cell disease are at higher risk for hearing loss than the general population. Moreover, the degree of risk is related to type of sickle cell disease. We found that persons with HbSC disease appear to have the greatest risk for hearing loss. Future investigations are required in this area to further determine the impact of sickle cell disease on various anatomical structures within the auditory system. REFERENCES Berry RA. Sickle cell anemia: audiological findings. J Am Audio1 SOC 1975;1:61-63. Charache S, Lubin B, Reid E, Eds. Management and Therapy of Sickle Cell Disease. Pub [NIH] 84-21 14, pp. 1-33. NIH USAHHS: Bethesda, MD, 1984. Freidman EM, Luban NLC, Herer GR, and Williams I. Sickle cell anemia and hearing. Ann Otorhinolaryngol 1980;89:342-347. Hemck JB. Peculiar elongated and sickle-shaped red blood corpuscles in a case of severe anemia. Arch Intern Med 1910;6:5 17-521.
Ear and Hearing, Vol. 12, No. 5,1991
Hotchkiss D. Estimates of the reported prevalence of hearing impairment. In Demographic Aspects of Hearing Impairment: Questions and Answers, 2nd Ed. Center for Assessment and Demographic Studies: Gallaudet University, 1989. Kimura R and Perlman H. Arterial obstruction of the labyrinth, Part I. Cochlear changes. Ann Otorhinolaryngol 1958;67:5-24. Morganstein KM and Manace ED. Temporal bone histopathology in sickle cell disease. Laryngoscope 1969;79:2172-2 180. Orchick DJ and Dunn JW. Sickle cell anemia and sudden deafness. Arch Otol 1977;103:369-370. Scott D. Sickle cell anemia and hearing loss. Concerns for minority groups in communication disorders. ASHA Report 1986;I6:6973. Sharp M and Orchick DJ. Auditory function in sickle cell anemia. Arch Otol 1978;104:322-324. Singer K. Studies of abnormal hemoglobins. Blood 195 1 ;6:413-428. Todd GB, Sejeant GR, and Larson MR. Sensonneural hearing loss in Jamaicans with SS disease. Acta Otol 1973;76:268-272. Urban Jr GE. Reversible sensorineural hearing loss associated with sickle cell crisis. Laryngoscope I973;83:633-638.
Acknowledgments: The authors thank E. A. Tolley, Ph.D., Department of Biostatistics and Epidemiology, University of Tennessee, Memphis and Scott Dodson of Memphis State University for their help with the statistical analysis of the data. In addition, we thank the Sickle Cell Support Group of the Diggs-Kraus Sickle Cell Center for their help during this project. Address reprint requests to Margie R. Crawford, Memphis State University, 807 Jefferson Avenue, Memphis, TN 38105. Received January 2, 1991; accepted May 22,1991.
Hearing Loss in Sickle Cell Disease
351
Prevalence of Hearina Loss in Adults with Sickle Cell Disease Margie R. Crawford; Herbert Jay Gould, PhD; Wally R. Smith, MD; Neal Beckford, MD; Willie Ruth Gibson; Loretta Bobo, MD Memphis State University, Memphis, Tennessee (M.R.C., H.J.G.) and University of Tennessee, Memphis, Tennessee (W. R.S., N.B., W.R.G., L.B.)
ABSTRACT Hearing status in 75 adult subjects with sickle cell disease was examined. Thirty-one (or 41%) of the subjects failed the hearing screening. When examined by hemoglobin type, it was found that persons with sickle cell C disease had the greatest incidence of hearing loss, although all subject groups exhibited greater prevalence rates than the general population. The results suggest that routine audiologic assessment be incorporated into the regular medical examination for adults with sickle cell disease (Ear Hear 12 5349-351).
SICKLE CELL ANEMIA was first documented as an abnormal blood condition characterized by sickleshaped cells (Hemck, 1910). The term “sickle cell disease” is used to encompass sickle cell anemia (HbSS) and sickle cell variants, such as sickle cell C disease (HbSC) and the sickle cell thalassemias (HbSB-thal). The disease is transmitted in a Mendelian fashion (Orchick & Dunn, 1977; Scott, 1986). Sickle cell trait (HbAS), not a form of the disease, occurs when one has the heterozygous state, representing the simultaneous occurrence of the sickle cell gene and the gene responsible for other hemoglobins (Freidman, Luban, Herer, & Williams, 1980; Scott, 1986). The major characteristics of sickle cell disease are hemolytic anemia, increased susceptibility to life threatening infections, and painful vaso-occlusive crises (Freidman et al, 1980). There is also chronic organ damage from regional ischemia and necrosis. Although there are no hematologic markers of impending painful crises, patients with HbSC and HbSB-thal have higher hematocrits and less severe complications than do patients with the HbSS form of the disease. Also, patients with higher percentages of hemoglobin F (HbF, fetal hemoglobin) and a higher number of alpha genes have less severe disease (Charache, Lubin, & Reid, 1984). Ear and Hearing, Vol. 12, No. 5,1991
The description and incidence of communication disorders for the sickle cell disease population is unknown (Berry, 1975). Sickle cell disease, by its very nature, suggests the potential for involvement throughout the entire neurologic system (Sharp & Orchick, 1977). Several attempts have been made to characterize the impact of sickle cell disease in the auditory system. Tissue changes associated with hypoxia and ischemia of inner ear structures were observed in the temporal bone of a patient who succumbed to a sickle cell crisis (Morganstein & Manace, 1969). Individuals with sickle cell disease have demonstrated reversible hearing loss over a 3 mo period (Orchick & Dunn, 1977; Urban, 1973). Several researchers have investigated the relationship between sickle cell disease and auditory dysfunction (Berry, 1973; Freidman et al, 1980; Sharp & Orchick, 1978). Berry (1973) observed no definitive pattern of hearing loss or abnormality. However, inconsistencies were observed across audiologic tests. Sharp and Orchick ( 1977)reported that peripheral hearing sensitivity was not significantly affected by the disease. However, time-compressed speech scores suggested that persons with sickle cell anemia may have impaired or reduced central auditory function. Freidman et a1 (1980) observed that the incidence of hearing loss was higher for the sickle cell anemia population than the general population. They concluded that the presence of any hearing loss in HbSS patients, even though it is of a mild degree, may reflect those patients with more serious complications arising from the disease. The largest study of hearing loss and sickle cell disease was performed on 83 adults with HbSS in the West Indies (Todd, Serjeant, & Larson, 1973). Todd et a1 ( 1973)found a deficit in hearing in 18 out of 83 patients (22%). However, they were unable to determine etiologic factors for the loss. These studies suggest that the prevalence of hearing loss among persons with sickle cell disease is greater than that of the general population. The purpose of this investigation was to determine the prevalence of hearing loss in a group of adults with sickle cell disease. In addition, the possible relationship between type of sickle cell disease, hematocrit levels and presence of hearing loss was investigated.
-
0196/0202/91/1205-0349$03.00/0 ‘ EARAND HEARING Copyright Q 1991 by Williams 8 Wilkins Printed in the U.S.A.
Hearing Loss in Sickle Cell Disease
349
hemoglobin type. When examined in this manner, subjects with HbSC exhibited the highest prevalence rate [9 out of 13 (69%) subjects]. HbSB+-thal subjects exhibited a prevalence of 50%, whereas subjects with HbSS had a 36% prevalence. Chi-square analysis of these three groups revealed that subjects with HbSC disease had a significantly greater prevalence of hearing loss ( p < 0.05, Table 2). Among hemoglobin types there were no statistically significant differences of hematocrit levels, percent HbF, or gender. The hearing loss subject group had a significantly higher mean age than the normal-hearing group (34 to 28 yr, p c 0.05, Student's t-test).
METHODS
Subjects (42 female and 33 male) were patients at the DigsKraus Sickle Cell Center at the Regional Medical Center (Memphis, TN). Patients ranged in age from 18 to 58 yr. with a mean age of 3 1 yr. Subjects were categorized by hemoglobin type (Table 1), determined by hemoglobin electrophoresis. The hearing status and hematocrit were assessed during a regular medical examination. Patients were free from crises and were not hospitalized for at least 1 mo before data collection. Percent HbF determinations were done by the alkali denaturation technique of Singer (Singer, 195 1). Bilateral hearing status was assessed in a nonsound-treated room measured for ambient noise (ANSI S3.1, 1977; standard for Criteria for Permissible Noise During Audiometric Testing). A portable audiometer (Maico MA27) was used to assess hearing. The patients were classified as having normal hearing or a hearing loss. The hearing loss group consisted of subjects with thresholds worse than 25 dB HL at 1000 through 8000 Hz and worse than 30 dBHL at 250 and 500 Hz for two or more frequencies for at least one ear. The looser criteria, at 250 and 500 Hz, were based on the ambient noise measures made. The nonloss group consisted of all remaining subjects. Statistical analysis was done by Student's I-test and Chi-square analysis for categorical data, and by Fisher's exact test when categories contained fewer than five members.
DISCUSSION
The results of this investigation suggest that the prevalence of hearing loss in adults with sickle cell disease, at 4 1 %, is greater than the general population. Demographic data show that approximately 7.2% of African Americans below 64 yr exhibit some type of hearing impairment (Hotchkiss, 1989). The cochlea is highly susceptible to disruption of blood flow, as it is supplied by a terminal artery. Any disruption in the normal blood supply, as occurs during vaso-occlusive crises, will result in reduced oxygen supply to cochlear structures (Kimura & Perlman, 1958). Interestingly, the present investigation found a much higher prevalence of hearing loss in adults with HbSC disease. An explanation for this finding might be the higher blood viscosity, possibly related to higher hematocrits in persons with HbSC disease. Further research is required to explain this phenomenon. Patients with HbSC disease typically do have more retinopathy, perhaps a parallel phenomenon related to blood viscosity. Although there was no significant difference between mean hematocrits for the hearing loss versus nonloss groups, there was an age difference between these two groups (34 versus 28 yr). These differences can be
RESULTS
There were 50 subjects with HbSS. The second group, 13, was comprised of subjects with HbSC. Eight subjects had HbSB+-thal, whereas the four remaining subjects had HbSBO-thal. Prevalence of hearing loss was determined by subject number, not by number of ears. A total of 31 subjects (41%) were classified as exhibiting hearing loss. Eighteen subjects came from the HbSS group. Nine subjects had HbSC disease and four had HbSB+-thal. None of the subjects with HbSBO-thal were found to have hearing loss. Prevalence of hearing loss was also examined by Table 1. Prevalence of hearing loss for sickle cell disease subjects N
N with Hearing Loss
YO Hearing Loss by
Hemoglobin Type Sickle cell anemia (HbSS) Sickle cell C disease (HbSC) Sickle cell-thalassemia disease (HbSP+-thal) Sickle cell-thalassemia disease (HbSBO-thal)
50 13 8 4
18 9 4 0
36% 69% 50%
Total
75
31
Hemoglobin Type
Table 2. Chi-square analysis by hemoglobin type Hemoglobin Type
Value
Probability
Sickle cell anemia (HbSS) Sickle cell C disease (HbSC) Sickle cell-thalassemia disease (HbSP+-thal) Sickle cell-thalassemia disease (HbSPo-thaI)
1.94 5.25 0.31 2.90
0.16 0.02' 0.58
0.08
Fisher's Exact Test 0.22
0.OP 0.70 0.14
* Significant at the 0.05 level. ~
350
Crawford el al
~~~~
Ear and Hearing, Vol. 12, No. 5,1991
explained by prolonged exposure to repeated or continued ischemia as a factor for increased susceptibility to hearing loss. These findings suggest the need for routine audiologic assessment for adults with sickle cell disease. It is likely that a number of patients will benefit from amplification, management, and counseling of hearing loss. In summary, 41 ?6 of the subjects in this study exhibited hearing loss. Our findings suggest that persons with sickle cell disease are at higher risk for hearing loss than the general population. Moreover, the degree of risk is related to type of sickle cell disease. We found that persons with HbSC disease appear to have the greatest risk for hearing loss. Future investigations are required in this area to further determine the impact of sickle cell disease on various anatomical structures within the auditory system. REFERENCES Berry RA. Sickle cell anemia: audiological findings. J Am Audio1 SOC 1975;1:61-63. Charache S, Lubin B, Reid E, Eds. Management and Therapy of Sickle Cell Disease. Pub [NIH] 84-21 14, pp. 1-33. NIH USAHHS: Bethesda, MD, 1984. Freidman EM, Luban NLC, Herer GR, and Williams I. Sickle cell anemia and hearing. Ann Otorhinolaryngol 1980;89:342-347. Hemck JB. Peculiar elongated and sickle-shaped red blood corpuscles in a case of severe anemia. Arch Intern Med 1910;6:5 17-521.
Ear and Hearing, Vol. 12, No. 5,1991
Hotchkiss D. Estimates of the reported prevalence of hearing impairment. In Demographic Aspects of Hearing Impairment: Questions and Answers, 2nd Ed. Center for Assessment and Demographic Studies: Gallaudet University, 1989. Kimura R and Perlman H. Arterial obstruction of the labyrinth, Part I. Cochlear changes. Ann Otorhinolaryngol 1958;67:5-24. Morganstein KM and Manace ED. Temporal bone histopathology in sickle cell disease. Laryngoscope 1969;79:2172-2 180. Orchick DJ and Dunn JW. Sickle cell anemia and sudden deafness. Arch Otol 1977;103:369-370. Scott D. Sickle cell anemia and hearing loss. Concerns for minority groups in communication disorders. ASHA Report 1986;I6:6973. Sharp M and Orchick DJ. Auditory function in sickle cell anemia. Arch Otol 1978;104:322-324. Singer K. Studies of abnormal hemoglobins. Blood 195 1 ;6:413-428. Todd GB, Sejeant GR, and Larson MR. Sensonneural hearing loss in Jamaicans with SS disease. Acta Otol 1973;76:268-272. Urban Jr GE. Reversible sensorineural hearing loss associated with sickle cell crisis. Laryngoscope I973;83:633-638.
Acknowledgments: The authors thank E. A. Tolley, Ph.D., Department of Biostatistics and Epidemiology, University of Tennessee, Memphis and Scott Dodson of Memphis State University for their help with the statistical analysis of the data. In addition, we thank the Sickle Cell Support Group of the Diggs-Kraus Sickle Cell Center for their help during this project. Address reprint requests to Margie R. Crawford, Memphis State University, 807 Jefferson Avenue, Memphis, TN 38105. Received January 2, 1991; accepted May 22,1991.
Hearing Loss in Sickle Cell Disease
351
