Page 74 - Effects of radiotherapy and hyperbaric oxygen therapy on oral microcirculation Renee Helmers

Chapter 4
ABSTRACT
Background: Late side effects of radiotherapy (RT) in the treatment for head and neck malignancies involve an inadequate healing response of the distressed tissue due to RT induced hypovascularity. The aim of this study was to develop a pilot model in which vascular alterations associated with late irradiation (IR) injury could be measured in rabbit oral mucosa and mandibular bone.
Materials and methods: Eight male New Zealand White rabbits were divided over 4 treatment groups. Group I-III received 4 fractions of RT (5.6 Gy, 6.5 Gy and 8 Gy respectively) and group IV received 1 fraction of 30 Gy. Oral microcirculatory measurements were performed at baseline (before RT) and once a week during 11 consecutive weeks after RT assessing perfusion parameters, i.e. total vessel density (TVD), perfused vessel density (PVD), proportion of perfused vessels (PPV) and microvascular flow index (MFI). Post-mortem histopathology specimens were analyzed.
Results: 5 weeks after RT, TVD and PVD in all groups showed a decrease of >10% compared to baseline, a significant difference was observed for groups I, II and IV (p<0.05). At T11 no lasting effect of decreased vessel density was observed. PPV and MFI remained unaltered at all time points. Group IV showed a marked difference in scattered telangiectasia-like microangiopathies, histological necrosis and loss of vasculature. Conclusion: No significant lasting effect in mucosal microcirculation density due to IR damage was detected. Observed changes in microcirculation vasculature and histology may align preliminary tissue transition towards clinical pathology in a very early state associated with late IR injury in the oral compartment.
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