Severe Hearing Loss from Pediatric Brain Tumor Treatment May Cause Cognitive Difficulties

Children diagnosed with embryonal brain tumors who have experienced treatment-related hearing loss exhibited greater difficulties reading — in particular, with phonological skills and processing speed, according to study results published in the Journal of Clinical Oncology.

Most importantly, the study findings highlighted the importance of developing interventions to help survivors become better readers, according to Dr. Heather Conklin — study corresponding author, member of the Psychology Department and chief of the Section of Neuropsychology at St. Jude Children’s Research Hospital.

“It is really important to be closely monitoring hearing in these children at risk,” she said in an interview with CURE. “We also need to make sure those children for whom we are recommending aided hearing are adherent, in order to maximize their access to sound at home and in the classroom.”

Pediatric survivors of brain tumors are typically at risk for cognitive declines that are associated with the treatment that they received or the disease itself. To expand on this existing knowledge, Conklin and colleagues evaluated the core neuro-cognitive processes that may result in reading difficulties among 260 children and young adults aged 3 to 21 years with treatment-related toxicity to the ears, including 64 with severe hearing loss.

“By studying cognitive problems we better understand mechanisms; for example, which chemotherapies are more likely to cause a problem or what brain areas are involved. By knowing that information we can refine cancer-directed therapy by using different agents or approaches that will lead to better outcomes so we have less children with hearing loss,” Conklin said. “Also, knowing specifically the types of cognitive problems they are having — not just reading problems in general- allows us to appropriately target our interventions.”

The researchers analyzed eight neurocognitive variables that support reading, such as phonemics (unit of sound to decode words), fluency and comprehension, and contributory cognitive processes, such as working memory and processing speed.

The treatment protocol among these patients was surgery, risk-adapted craniospinal irradiation and chemotherapy.

Patients with severe hearing loss performed significantly worse across all of the variables, except for tasks assessing awareness of sounds and working memory, compared with children with normal hearing or mild hearing loss.

When the researchers controlled for age at diagnosis and risk-adapted craniospinal irradiation dose, phonemic skills, phonetic decoding, reading comprehension and speed of information processing was still significantly worse in children with severe hearing loss.

While most of the data were not surprising to Conklin, one finding was. “When we looked back at our data more specifically with respect to age of treatment, we learned that patients under 7 were particularly at risk for hearing and reading issues, which gave us some more hints into how we need to target our patients for intervention,” she said.

As a result, further research on reading interventions, hearing aid adherence and additional agents to prevent hearing loss are warranted.

“Future research assessing which interventions (and at what time in treatment) are most efficacious in bolstering reading skills in children undergoing cancer-directed treatment is crucial and may have important implications for others with (severe hearing loss),” the researchers concluded. “In addition, future research regarding the neurocognitive effects of SNHL should carefully document variables such as whether an aided device was recommended, age at first use, typical day-to-day use, and whether it was used during cognitive testing. Prospective studies investigating hearing aid adherence and neuro- cognitive outcomes would be particularly interesting.”