Submandibular gland botulinum toxin injections for drooling: the safe and risky zones

Abstract

Springer-Verlag 2011 In an interesting cadaveric study to document the anatomical landmarks of the submandibular gland (SMG) for botulinum toxin (BTX) injections which can be used for drooling. Lee et al. [1] mentioned that there were no major structures located within the parenchyma of the SMGs, while the facial artery (FA) or its branches were their main blood supply. In most cases, the arteries ran and branched just under the mandible. Based on these anatomical data, the safety zone for the injection was 1.5 cm below the inferior line of the mandible on the lateral view. They concluded that this safety zone could be the site of BTX injections into the SMG, particularly for injections without ultrasound guidance. It is an axiom in surgery to expect the unexpected for avoidance of complications. The same rule should be applied in the treatment of drooling by intrasalivary gland injection with BTX. The safety zone identified by Lee et al. [4] could be risky in patients with vascular variants. The FA may be absent [2]. We recently detected abnormal branching pattern of the left external carotid artery (ECA) in an old man during the dissection of 25 cadavers [3]. There was FA agenesis compensated by concurrent ipsilateral large transverse facial and submental arteries arising from the ECA. In our case, the SMG received dual arterial