IMPROVING THE EVALUATION OF SENSORINEURAL HEARING LOSS IN CHILDREN

Abstract

In reaction to the following paper: Lin JW, Chowdhury N, Mody A, Tonini R, Emery C, Haymond J, Oghalai JS. Comprehensive diagnostic battery for evaluating sensorineural hearing loss in children. Otol Neurotol 2011;32(2):259-64. To the Editor: We have read the article of Lin et al. (1) with interest. In our center, we have formed a multidisciplinary team that focuses on the cause of sensorineural hearing loss (SNHL) in children, and we are pleased with the well-written overview of useful diagnostic tests. However, while analyzing the results, a few vital questions arose. A main cause of congenital SNHL is cytomegalovirus (CMV). Using the Guthrie card as diagnostic tool, congenital CMV infections can be diagnosed without the use of magnetic resonance imaging (MRI). Moreover, MRI abnormalities are only present in a subgroup of patients affected by CMV (2). We would therefore recommend the addition of the Guthrie card evaluation to the diagnostic battery, as it is able to detect CMV infection in the absence of magnetic resonance abnormalities and requires no cumbersome additional diagnostic procedures for the patient. Pendred syndrome also is associated with SNHL and estimated to be responsible for up to 7% of SNHL in young children (3). One of its common features is a unilaterally or bilaterally enlarged vestibular aqueduct (EVA). In line with this, the article describes the existence of 20 patients (8%) with an EVA. Surprisingly, the results of the genetic consultation have not shown any children with Pendred syndrome. Was Pendred syndrome not tested for or simply not found? Considering there may be children with underlying Pendred syndrome within the group of 20 EVA cases, how would goiter or thyroid pathology be anticipated in these cases? In our opinion, the age at which the investigations take place is of great importance. Anatomic abnormalities may become more visible over time, and some abnormalities only become symptomatic from a certain age (such as retinitis pigmentosa or progressive hearing loss with an EVA). Furthermore, certain diagnostics (e.g., computed tomography without narcosis or MRI with narcosis) may be more favorable because of the age of the child. The presented subgroups (Table 2) of "passed hearing screening," "failed hearing screening," and "acquired SNHL" already imply different presentation and presumably different mean age at diagnosis of SNHL. Unfortunately, figures of the age range of the respective subgroups are missing. The question arises whether differences in outcome of the diagnostic battery are related to differences in the mean age at diagnosis of SNHL. Furthermore, as the article points out the yield of several diagnostic instruments per subgroup (Table 2), one could consider tailoring the sequence of the diagnostic battery to each subgroup. Finally, we would like to address the renal ultrasound (US). It is proposed that it should only be used in suspicion of branchio-oto-renal syndrome. However, the results in the article suggest that even in the presence of US abnormalities, branchio-oto-renal syndrome could not be genetically confirmed, making the contribution of US to diagnosis or cause unclear. This article proposes a selection of diagnostic tests that may guide the clinician in the formation of an effective diagnostic battery. However, a sequential diagnostic procedure may be a more rational approach. For example, the diagnostic path could start with a search for the most likely diagnoses (CMV and connexin 26). If the results of these tests are negative, this may be followed by more invasive and expensive diagnostics (radiologic imaging and other genetic tests). By tailoring the diagnostic battery to the individual patient in this way, cost-effectiveness is improved, and the burden of the diagnostic procedure minimalized, without sacrificing the sensitivity of the full set of diagnostic modalities. We would like to thank the authors for their extensive work. Like the authors, we strongly believe that a multidisciplinary approach is the most effective way in uncovering the cause of SNHL in children. It will be very helpful in creating a cost-effective and less invasive diagnostic battery. Their work contributes even more than mentioned in their own discussion. Paul Merkus, M.D., Ph.D. Justine J. Vogel, M.D. Erik F. Hensen, M.D. Department of Otorhinolaryngology-Head and Neck Surgery VU University Medical Center Amsterdam, The Netherlands [email protected]