Ir J Med Sci (2011) 180:781–782 DOI 10.1007/s11845-011-0707-3

LETTER TO THE EDITOR

Sensorineural hearing loss in pregnancy: an alternative, simpler possible explanation A. Pirodda • G. G. Ferri • C. Borghi

Received: 23 February 2011 / Accepted: 21 March 2011 / Published online: 20 April 2011 Ó Royal Academy of Medicine in Ireland 2011

An interesting paper recently published by Kenny et al. [1] in the Irish Journal of Medical Science reports a case of two episodes of sudden sensorineural hearing loss (SSHL) which occurred to the same patient during two consecutive pregnancies. The possible underlying mechanisms are discussed and include increased endolymphatic pressure linked to changes in CSF pressure associated to a patent cochlear aqueduct, hormone changes, oedema, autoimmune disorders, increased activation of blood coagulation and fibrinolysis during pregnancy. Furthermore, the possibility of an influence of altered anatomy and physiology of the epidural space is taken into account. However, the authors conclude that other possible aetiologies need to be excluded. SSHL still represents a challenging problem, despite its known frequent spontaneous recovery. The consideration that SSHL often involves young and healthy subjects, led to the hypothesis that in some instances an apparently ‘‘idiopathic’’ origin could be represented by hypotension episodes followed by an abnormal vasomotor reaction [2]. This hypothesis, which was also supported by experimental models [3, 4], was subsequently confirmed by studies both on healthy subjects [5, 6] and on cardiovascular patients [7, 8]. This explains a possible origin of some cases of SSHL previously labelled ‘‘idiopathic’’. Otherwise healthy A. Pirodda
G. G. Ferri Department of Specialist Surgical and Anesthesiological Sciences, University of Bologna, Bologna, Italy C. Borghi Department of Internal Medicine, University of Bologna, Bologna, Italy G. G. Ferri (&) S. Orsola-Malpighi University Hospital, Via Massarenti 9, 40138 Bologna, Italy e-mail: [email protected]

sufferers from SSHL revealed lower blood pressure levels than the control group [5]. The importance of an autonomic dysregulation was outlined [6]. Patients with hypertension under antihypertensive therapy had a far more prominent prevalence of tinnitus when submitted to an ‘‘aggressive’’ treatment to lower their pressure values [7]. More prominent prevalence of tinnitus was recorded in patients with severe heart failure [8].These observations can be explained by considering the particular features of the inner ear, that is a highly energy requiring sensorial organ supported by a circulation of terminal type. In our opinion, hemodynamic changes occurring during pregnancy can represent a reliable precondition for the pathogenesis of SSHL. In healthy pregnant women blood pressure steadily falls until the middle of gestation and then rises until delivery [9]; this fall is considered to be a physiological phenomenon that is triggered by a decrease in total peripheral vascular resistance [10]: The normal vascular adjustments occurring during pregnancy are likely to represent, in some subjects at least, a facilitating factor for the onset of SSHL in the absence of a real pathological condition below. As a practical consequence of these remarks, it could be useful to match the blood pressure levels during pregnancy with eventual preclinical warning of inner ear sufferance as transient tinnitus or dizziness or aural fullness.

References 1. Kenny R, Patil N, Considine N (2011) Sudden (reversible) sensorineural hearing loss in pregnancy. Ir J Med Sci 180(1):79–84 2. Pirodda A, Saggese D, Giausa G, Ferri GG, Nascetti S, Gaddi A (1997) Can hypotension episodes cause cochlea damage in young subjects? Med Hypotheses 48:195–196

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782 3. Hultcrantz E, Linder J, Angelborg C (1977) Sympathetic effects on cochlea blood flow at different blood pressure levels. INSERM 68:71–78 4. Maass B (1981) Autonomic nervous system and hearing. Adv Otorhinolaryngol 27:14–25 5. Pirodda A, Ferri GG, Modugno GC, Borghi C (2001) Systemic hypotension and the development of acute sensorineural hearing loss in young healthy subjects. Arch Otolaryngol Head Neck Surg 127:1049–1052 6. Pirodda A, Ferri GG, Montana T, Riggio R, Innocenti G, Di Nino G (2004) Hypotension as an isolated factor may not be sufficient to provoke hearing impairment. J Laryngol Otol 118:941–945 7. Borghi C, Brandolini C, Prandin MG, Dormi A, Modugno GC, Pirodda A (2005) Prevalence of tinnitus in patients with

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hypertension and the impact of different antihypertensive drugs on the incidence of tinnitus: a single-blind, observational study. Curr Ther Res Clin Exp 66:420–432 8. Degli Esposti D, Cosentino ER, Santi F et al. (2007) Tinnitus and blood pressure values in heart failure patients. Proceedings of the 17th European Meeting on Hypertension, Milan, p S171 9. Hermida RC, Ayala DE, Iglesias M (2001) Predictable blood pressure variability in healthy and complicated pregnancies. Hypertension 38:736–741 10. Silva LM, Steegers EAP, Burdorf A et al (2008) No midpregnancy fall in diastolic blood pressure in women with a low educational level. The generation R study. Hypertension 52:645–651