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Abnormal hippocampal development in children with medulloblastoma treated with risk-adapted irradiation
Bonnie J Nagel1, Shawna L Palmer, Wilburn E Reddick
1Division of Behavioral Medicine, St Jude Children's Research Hospital, Memphis, TN, USA.
Insights
Pediatric medulloblastoma survivors show abnormal hippocampal volume changes after treatment, potentially explaining memory deficits. These volumes normalize over time, but factors like sex and shunt placement impact recovery.
Area of Science:
- Neuroscience
- Pediatric Oncology
- Radiology
Background:
- Medulloblastoma treatment in children often leads to neurocognitive deficits, particularly affecting memory.
- The precise neuropathological basis for these memory impairments remains unclear.
- Hippocampal integrity is recognized as vital for new episodic memory formation.
Purpose of the Study:
- To investigate longitudinal changes in hippocampal volume in pediatric medulloblastoma patients.
- To determine if abnormal hippocampal volume development correlates with memory dysfunction post-treatment.
Main Methods:
- Serial MRI scans were analyzed for 25 pediatric medulloblastoma patients over 5 years post-treatment.
- Manual tracing of right and left hippocampal volumes was performed on contiguous coronal sections.
- Random coefficient models assessed longitudinal hippocampal volume changes relative to diagnosis time.
Main Results:
- Both hippocampal volumes initially decreased post-treatment, with recovery towards normal growth patterns around 2-3 years.
- Volume loss was most pronounced in the posterior hippocampal regions.
- Female sex, lower parental education, shunt placement, and seizure history negatively impacted hippocampal volume.
Conclusions:
- Pediatric medulloblastoma survivors exhibit altered hippocampal volume development post-treatment.
- Further research into radiation dose effects on specific hippocampal regions is recommended.
- Exploring the link between radiation therapy, memory issues, and hippocampal changes is crucial.
Background And Purpose:
Children with medulloblastoma demonstrate post-treatment neurocognitive deficits in a number of areas, including memory performance. However, there is no definitive understanding of the neuropathology underlying these functional deficits. Previous literature has reported that hippocampal integrity is crucial to the acquisition of new episodic memories. Therefore, we hypothesized that longitudinal hippocampal volume measurements are abnormal in patients with medulloblastoma and thereby provide a possible substrate for explaining memory dysfunction.
Methods:
Twenty-five pediatric patients underwent 159 serial MR imaging examinations (mean = six examinations per patient) for up to 5 years after irradiation and chemotherapy treatment for medulloblastoma. Right and left hippocampal volumes were obtained by manually tracing 1.5-mm contiguous coronal sections through the structure. Random coefficient models were used to examine longitudinal change in hippocampal volume as a function of time after diagnosis.
Results:
Both right and left hippocampal volumes initially decreased after treatment. This abnormal volume pattern continued until approximately 2-3 years after diagnosis, when hippocampal volumes returned toward a normal positive growth pattern. Volume loss occurred predominately in the posterior regions. Female sex, low parental education, shunt placement, and positive seizure history all had a significant negative impact on hippocampal volume.
Conclusion:
Pediatric medulloblastoma survivors demonstrate an abnormal pattern of hippocampal volume development after treatment. Radiation dose mapping may expand our understanding of region-specific changes in hippocampal volume. Further exploration of the relationships between radiation therapy, memory dysfunction, and hippocampal pathology in this population is warranted.
