Researchers have discovered that the early diagnosis and initiation of enzyme replacement therapy (ERT) within the first 2 weeks of life of patients with infant-onset Pompe disease (IOPD) may improve hearing outcomes, according to a study published in the Orphanet Journal of Rare Diseases.
This is the largest cohort study to examine hearing data in IOPD patients who have received ERT early. As a result of their findings, the authors recommended that “clinicians should be vigilant for the hearing issues associated with IOPD and intervene early if any hearing impairment occurs in their IOPD patients.”
Available literature establishes the importance of ERT in improving the survival rates of IOPD patients. In patients who do survive, hearing impairment is commonly observed. Although many studies have centered on the use of ERT to improve outcomes in patients with Pompe disease, no others have so far investigated the impact of starting ERT early on hearing outcomes. Thus, the purpose of this study is to examine the impact of early ERT on the hearing functions of IOPD patients.
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This study was conducted in Taiwan, which has a newborn screening program for Pompe disease. Researchers recruited 19 children who were referred to Taipei Veterans General Hospital and received a confirmed IOPD diagnosis between January 1, 2010, and January 31, 2018. All referred newborns were started on ERT within 4 hours of admission if they fulfilled the following criteria:
(1) General hypotonia
(2) An creatine kinase level above 250 m/L
(3) GAA activity below 0.50 mmol/L/h upon initial dried blood spot analysis
(4) A left ventricular mass index higher than 80 g/m2
Researchers used a range of established hearing tests to test for hearing function, with the most common being pure-tone threshold testing, which analyzes both bone and air conduction. The type of hearing loss (HL) was graded according to definitions set by the American Speech-Language-Hearing Association (ASHA), which has 7 ranges, from normal (< -10dB and ≤15 dB HL) to profound (>90 dB HL).
Results show that the patients in the cohort, all of whom received early ERT (average initiation time of 11.05 days), had a lower hearing impairment rate (31.6% hearing impairment in the last evaluation after treatment). The most common type of hearing loss was sensorineural hearing loss, which is consistent with previous studies.
“The better hearing outcomes reported in our cohort indicate that early ERT could have a positive effect not only on the development of the cochlear and nervous systems but also on the muscular components associated with Eustachian tube or middle ear function,” the authors of the study wrote.
Hsueh CY, Huang CY, Yang CF, et al. Hearing characteristics of infantile-onset Pompe disease after early enzyme-replacement therapy. Orphanet J Rare Dis. Published online August 5, 2021. doi:10.1186/s13023-021-01817-1