Locating the mental foramen at the bedside with point of care ultrasound imaging

Abstract

Introduction: Ultrasound guided neuro-anaesthesia is a developing field of interest to clinicians from various disciplines. The objective of this proof of concept study was to explore the ability, ease and rapidity of ultrasonography in locating the mental foramen. Methods: A convenience sample of 100 patients aged 18 years or older, with no known pathology to the mandibular region, that presented to a single urban ED were enrolled. All patients underwent an ultrasound examination on both sides of the face to locate the mental foramina. Results: A total of 100 patients' mental foramina were studied. Mean age was 35.7 years (SD 9.1 years), 50% were black and 25% each were asian and white. The mental foramina were ultrasonographically identified in all (100%) of the subjects in the study group. Although requiring a larger quantity of ultrasound gel, the mental foramina were also visualized in all twelve subjects with facial hair. Three out of the 100 subjects were noted to have accessory mental foramina. The overall mean time taken to locate the first mental foramen in each patient was 16.1 seconds (SD 12.9 seconds). For the first 25 subjects studied, the mean time taken was 34.7 seconds (SD 13.4 seconds), whereas for the next 75 subjects studied, the mean time taken was 9.9 seconds (SD 3.0 seconds). Conclusion: Bedside ultrasound imaging is a potentially reliable method to identify and locate the mental foramen. With practice and experience, the mental foramen can be more easily identified.