Table 2.

Characteristics of studies included in the review

Study	Study design	Participants	Exposure duration	Outcome measure	Results	Conclusion
Karlidaǧ et al (2004)	Cross sectional	57 in study group and 32 in age matched control group	4–23 years	PTA, high-frequency audiometry, immittance audiometry (tympanometry and stapedial relflex)	Significant higher hearing threshold found in study group for 4, 6, 8, 14 and 16 kHz compared to the control group. The mean threshold of speech frequencies (500, 1000 and 2000 Hz) for study group were have significant higher threshold compared to control group. No difference found for immittance measurements	Authors suggest that subjects who exposed to radiation for a long period should be evaluated periodically using both standard and high-frequency audiometry could be beneficial
Pooja et al (2018)	Case control	60 subjects in study group and 54 age- and sex-matched subjects in control group	3–19 years	Tuning fork test (Rinne, weber and absolute bone conduction tests), PTA, tympanometry, stapedial reflex and TEOAE at 1, 2 and 4 kHz	Significant correlation found between exposure duration and hearing loss at 500 Hz and 10 kHz. Significant higher hearing threshold found for 12.5 and 16 kHz for study group compared to control group	Most of the frequencies have higher thresholds in the study group compared to controls. But only 12.5 and 16 kHz were significant. Cases also were more symptomatic than controls. If study done using larger group with long radiation exposure duration these changes might become significant