PATTERN OF HEARING LOSS IN SICKLE CELL DISEASE HAMAD AL-MUHAIMEED, M.D. Professor/Consultant ORL Department of ORL-H & NS King Abdul Aziz University Hospital George Thomas M.P. Divakaran Nasher H. Al Sedran

Pattern of HL in SCD Discussion Incidence: % in different studies Study Incidence U.K. 13% Nigeria 21.4% Jamaica 21.7% Qatif, S.A. 19% Southwest, S.A. 23.8% Najran (present study ) 36%

Pattern of HL in SCD Hematological indices Patients with SNHL Patients without SNHL P-value Hb9.5 +/- 2.1 (n=15)9.6 +/- 2.4 (n=31)0.4 Hbs66.3 +/ (n=15)59.2 +/ (n=24)0.2 HbF11.4 +/ (n=13)5.5 +/- 8.8 (n=22)0.1 HbA32 +/ (n=11)39.1 +/ (n=24)0.3 HbA20.5 +/-.87 (n=11)0.3 +/ (n=23)0.3 Distribution of hematological indices for patients with and without SNHL (mean +/- SD)

Pattern of HL in SCD Sex Patients with SNHL Patients without SNHL Male 616 Female1216 Sex distribution of SNHL in 50 patients with SCD X = , d.f. = 1, P =

Pattern of HL in SCD Material & Methods Criteria used to determine deafness: * HL > 20 dB at two or more frequencies in one or both ears.

Pattern of HL in SCD Discussion Elevated levels of HbF have a protective effect in the severity of SCD Al-Awami et al, 1986

Pattern of HL in SCD SNHL has been recognized as a complication in patients with SCD for > 30 years Mongestein & Monce, 1969

Pattern of HL in SCD Patient with SCD have a much higher incidence of SNHL with a variable degree of severity Friedman et al, 1980

Pattern of HL in SCD The site of damage is thought to be in the cochlea (Serjeant et al, 1975) or retrocochlear and cochlear (Gould et al, 1991).

Pattern of HL in SCD Aim To establish the incidence and describe the pattern of SNHL among homozygous SCD in Najran.

Pattern of HL in SCD Material & Methods Retrospective study 50 homozygous SCD (Hb electrophoresis, positive sickling test) June '93 to end Aug Age: 4 to 45 years Control group, matched for age & sex (Hb-AA, 40)

Pattern of HL in SCD Age Patients with SNHL Patients without SNHL </= 12 years 914 >/= 13 years918 Age distribution of SNHL in 50 patients with SCD 2 X = , d.f. = 1, P =

Pattern of HL in SCD Severity of SNHL No. of ears affected (%) Mild (25-40 dB)17 (73.9) Moderate (41-60 dB)4 (47.4) Severe (> 60 dB)2 (8.7) Pattern of SNHL in 23 ears from patients with SCD

Pattern of HL in SCD Discussion – HL has been reported in homozygous (HbSS) & double heterozygous states. – Gradual onset Astina and Ankra Badu, 1988

Pattern of HL in SCD Discussion In the Kingdom of Saudi Arabia, there are two endemic areas for SCD: 1) Eastern province 2) Southwestern province The increased incidence in this series maybe attributed to:  Poor socio-economic status  Poor educational background  Less access to health care facilities -- living in the desert & remote villages

Pattern of HL in SCD Discussion Pathogenesis of SNHL in SCD: 1) Compression of the IAC by expan- sion of petrous bone marrow 2) Neural involvement 3) Ischaemic changes in the cochlea The widely accepted hypothesis is due to ischaemia & hypoxia of stria vascularis & organ of corti.

Pattern of HL in SCD Discussion Unique feature detected in the present series is the predominance of unilateral (72%) as compared to bilateral (28%) HL. The reason is not clear -- could be the variability of the vascular supply of the cochlea or other structural differences which make one side more vulnerable to ischaemia.

Pattern of HL in SCD Discussion C.T. scan temporal bone and ERA were used to exclude retrocochlear pathology in unilateral SNHL.

Pattern of HL in SCD Discussion The incidence of HL did not appear to increase with increasing age.

Pattern of HL in SCD Conclusions – SNHL as a complication of SCD occurs more frequently than earlier reports. – Poor accessibility to health care facilities may account for higher incidence. – None of the clinical & laboratory parameters analyzed were helpful in predicting susceptability to SNHL. – Easier access to health care and regular hearing assessment should be extended to all patients.