STUDIES ON THE EFFECT OF IRRADIATION IN THE SALIVARY GLANDS

RELATIONSHIP BETWEEN XEROSTOMIA AND SECRETORY FUNCTION OF EXPOSED SALIVARY GLANDS

Abstract

In some tumors in the head and neck, radiation therapy is the treatment of choice to keep the oral function, while in others it may be used in conjunction with surgery or chemotherapy.
Radiation therapy, however, as any therapeutic process is not without side effect. The associated morbidity includes mucositis, epidermitis, xerostomia, radiation caries, pulpal damage and a reduced ability of the tissues to infection caused by various vascular and bone changes.
Patients receiving radiation therapy for oral lesions, specially including the salivary gland, usually develop xerostomia, a condition of decreased salivary potential with a resultant“dry mouth”.
The degree of xerostomia is directly related to the dose and volume of irradiated salivary tissue.
The purpose of this study is to examine whether the excretion of ^99mTc from the parotid can give any further information about the functional state of the gland and whether there are any correlation between sialography and RI-sialometry in degree of radiation damage in 43 irradiated cases.
I classified the xerostomia into Grade 0∼Grade III under the base of the patients complaints.
Grade 0: there are no influence at meal or conversation
Grade I: they feel suffering slightly at meal or conversation, but need not to drink water or milk to eat dry food.
Grade II: they feel pain at meal or conversation and need to drink much water to eat dry food.
Grade III: they need to drink water even at conversation and have dry mouth obviously.
85% of the patients who were irradiated whole parotid glands showed Grade II or Grade III, 14 of 15 cases (93%) who were exposed partially in the area of parotid gland showed Grade I. The degree of xerostomia in 17 of 21 cases (81%) who were totally 40 Gy exposed was Grade I and that in 20 of 21 patients (95%) who were more than 50Gy irrandiated was Grade II or Grade III.
From the present study it might be concluded that there is good agreement between the functional capacity of the investigated parotid glands recorded by sialography and RI-sialometry.
The classification by clinical complaints might be of value for evaluation of the functional capacity of irradiated parotid gland (xerostomia).
The histopathologic changes observed in irradiated parotid glands were in harmony with the clinical features of glands. In animal experiment, the same result was obtained.
The possible usefulness of RI-sialometry as a indication of radiation exposure is suggested.