Long-term cerebral effects of small doses of x-irradiation in childhood as manifested in adult visual evoked responses

Area of Science:

• Neurology
• Radiology
• Pediatrics

Background:

• Between 1949-1960, ~20,000 Israeli children (1-15 years) received cerebral x-radiation (XR) for tinea capitis.
• Radiation doses to cerebral hemispheres reached up to 140 rads.

Purpose of the Study:

• To investigate potential long-term neurological effects of low-dose pediatric XR exposure.
• To analyze functional brain changes using visual evoked responses (VERs) in adults previously treated with XR.

Main Methods:

• Stratified sampling selected 44 adults irradiated as children and 57 controls.
• VERs were recorded using bilateral occipital leads (international 10-20 system) following diffuse white-flash stimulation.
• Statistical analysis of averaged VER data identified differences between irradiated subjects and controls.

Main Results:

• Significant differences were detected in VER averages between the irradiated group and controls.
• Left cerebral hemispheres showed greater involvement, correlating with higher XR doses to the left side.
• Differences in VERs suggest delayed, potentially permanent functional damage to the central nervous system, possibly involving subcortical structures.

Conclusions:

• Low-dose pediatric XR exposure may cause delayed, permanent functional damage to the immature human brain.
• VER analysis provides evidence for the potential hazards of XR in children.
• Findings highlight the need for caution regarding radiation exposure in pediatric populations.