The use of human growth hormone therapy (hGHT) has increased substantially in recent years, particularly following the FDA addition of idiopathic short stature as an approved indication for hGHT. Although no studies have shown an effect of hGHT on hearing loss in general, we studied the effects of hGHT on two of our pediatric cochlear implant recipients.
The first patient, S1, was diagnosed with a bilateral profound sensorineural hearing loss shortly after birth. He received his first implant in the right ear at 10 months and in the left ear at 4 years. When he was 8 years old, his pediatrician began hGHT (Norditropin) because of his unexpectedly poor growth rate, which was based on predictions from parental height. Following four months of hGHT, S1’s speech recognition scores initially decreased from 90 percent to 72 percent in the right ear, while remaining stable at 40 percent in the left ear. Despite attempts to alter programming, work with hardware, and perform other troubleshooting, there was a further decrease in performance to 52 percent in the right ear and 28 percent in the left ear.
Because no reasons were identified for the decline, the parents and pediatrician, in conjunction with the cochlear implant team, decided to stop hGHT. This led to an initial increase in word recognition scores to 74 percent in the right ear and 68 percent in the left ear. The decision was then made not to resume hGHT until S1 reached the age of 12 years, when it was noted that he was still short in stature. Testing was done prior to the administration of the drug; a score of 80 percent was obtained in the right ear and 68 percent in the left ear. S1 was closely monitored for any changes in hearing, and after two months, the scores dropped to 52 percent in the right ear and 26 percent in the left ear. S1 is still receiving hGHT and continues to be closely monitored for hearing changes.
The second patient, S2, was diagnosed at birth with bilateral severe sensorineural hearing loss and benefited from hearing aids until the age of 8, at which time she received a cochlear implant in the left ear while continuing to use a hearing aid in the right ear. When she was 11 years old, the parents and pediatrician noted that S2 was short for her age, and she was put on a hGHT regimen. After several months, her word recognition scores decreased from 92 percent to 82 percent. Because S2 did not notice a big difference, hGHT was continued, but the parents decided to stop therapy after one year. Subsequently, S2’s word recognition score increased to 90 percent. Even though the decrease in performance for S2 was not as dramatic as that seen by S1, no other explanation for the decrease was found.
At this time, there is no known explanation why hGH has a negative effect on speech understanding with a cochlear implant. It is possible that the drug might cause an inflammatory reaction or other response that affects the transmission of the electrical signal, but the fundamental explanation is still unknown and requires further research. It is reasonable to closely monitor speech perception scores in children who undergo hGHT after receiving cochlear implants, however, because we have shown there is a possibility that hGHT can negatively affect performance with a cochlear implant and because the use of hGHT has increased.