Localization of Salivary Glands for Botulinum Toxin Treatment: Ultrasound Versus Landmark Guidance.

[BACKGROUND] Sialorrhea is a troublesome symptom in a variety of neurological diseases. Recently, local injection of botulinum toxin into the salivary glands was approved for treatment of sialorrhea, and injection guidance by anatomical landmarks was suggested.

[OBJECTIVE] To compare the accuracy of ultrasound versus previously proposed anatomical landmarks for localizing the salivary glands.

[METHODS] In a cross-sectional study in 21 adults, landmark positions (LM) of the parotid gland (PG) and the submandibular gland (SG) were identified following published recommendations. The ultrasound position (US) was defined as the position representing the maximum gland thickness. The distance between positions, gland thickness, and optimal injection depth were recorded by US.

[RESULTS] Gland thickness differed significantly between LM and US positions (PG, 4 vs. 17.8 mm; < 0.001; SG, 3.5 vs. 13.6 mm; < 0.001). The spatial deviation between the recommended LM and identified US positions in the horizontal plane was 21 mm to the posterior direction for the PG and 19.6 mm for the SG. The deviation in vertical orientation was small for both glands; however, there was a positive correlation between the distance from the SG to the mandibular bone with age. The optimal injection depth measured by US was 11.8 mm for the PG and 13.6 mm for the SG. This showed to be positively correlated with the body mass index.

[CONCLUSIONS] The position of the salivary glands differs from proposed landmarks and depends on the individual age and body weight; therefore, we recommend ultrasound guidance for injection.