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Radiotherapy Xerostomia — MFDS Part 1 MCQ

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ModerateHuman DiseaseRadiotherapy XerostomiaMFDS Part 1

A patient develops persistent oral dryness after bilateral head and neck radiotherapy in which the major salivary glands were within the treatment field. Sialometry confirms markedly reduced unstimulated and stimulated salivary flow. Which mechanism best accounts for this complication?

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Correct answer: B — Radiation injury to salivary acinar cells, reducing secretory capacity

The correct answer is B. When major salivary glands receive ionising radiation, injury and dysfunction of their secretory acinar cells reduce saliva production and alter its composition. This produces objective salivary-gland hypofunction and the subjective symptom of xerostomia; damage can persist after treatment. Taste receptor injury may cause dysgeusia and reduce gustatory stimulation but does not by itself explain markedly reduced unstimulated and stimulated flow. Fibrosis of the muscles of mastication causes trismus rather than gland hypofunction. Hypoglossal neuropathy causes weakness and impaired movement of the tongue. Psychological factors can influence the perception of oral dryness but cannot account for the confirmed reduction in salivary flow.

Reference: Li Y et al. Diagnosis, Prevention, and Treatment of Radiotherapy-Induced Xerostomia: A Review. Journal of Oncology. 2022. https://pubmed.ncbi.nlm.nih.gov/36065305/