title: Ultrasound-guided greater palatine nerve block: a case series of anatomical descriptions and clinical evaluations.
abstract: BACKGROUND
  Greater palatine nerve (GPN) block is commonly performed for maxillary and palatal anesthesia by using bony landmarks. Ultrasound (US) can be used to consistently identify greater palatine foramen (GPF) as a defect in the bony palate enabling US-guided injections near the foramen.
  
  
  METHODS
  We scanned and injected 16 undissected well-embalmed hemisectioned cadaveric heads after excluding major anatomical malformations. A linear high-frequency hockey stick probe (7-13 MHz) positioned in long axis to the hard palate visualized GPF as a discontinuity in the hard palate. US-guided injections of 0.1 mL India ink were made in an oblique plane. Specimens were dissected immediately after injection, and dye distribution was noted. The success rate of identification of GPF, number of attempts, and number of successful injections were recorded. The technique was evaluated clinically in 7 patients undergoing dental procedures. Five patients had US-guided injections, and 2 patients received US-assisted greater palatine canal blocks.
  
  
  RESULTS
  GPF was successfully identified in 16 hemisectioned heads (n = 16). In 7 of 16 hemisectioned cadaveric specimens (n = 7/16), needle pass was seen on the US and traces of India ink were found within the greater palatine canal and pterygopalatine fossa. In the remaining heads (n = 9/16), the dye was observed in the mucosal tissue of the hard palate anterior to the GPF or in the soft palate. Clinical evaluation reconfirmed successful identification of GPF by US in 6 of 7 patients (n = 6/7). US-guided injections were successful in 6 of the 8 attempted blocks (n = 6/8) with median number (range) of attempts being 2 (1-4). US-assisted injections were successful in 2 patients (n = 2/2).
  
  
  CONCLUSIONS
  US has the potential to successfully locate and characterize GPF in normal and edentulous maxilla. US-guided GPN blocks can be technically challenging. The clinical applicability of US guidance or assistance for GPN block needs further evaluation in a larger sample of patients.
authors: From the Departments of Anatomy and Cell Biology, Anesthesia and Perioperative Medicine, and Division of Oral and Maxillofacial Surgery, Western University, London, Ontario, Canada.
authors: Najmus
authors: N
authors: Sahar Hafeez
authors: Rakesh V
authors: RV
authors: Sondekoppam
authors: Sugantha
authors: S
authors: Ganapathy
authors: Jerrold E
authors: JE
authors: Armstrong
authors: Michael
authors: M
authors: Shimizu
authors: Marjorie
authors: M
authors: Johnson
authors: Peter
authors: P
authors: Merrifield
authors: Khadry A
authors: KA
authors: Galil
mesh_terms: D000328:Adult; D000766:Anesthesia, Dental; D002102:Cadaver; D002244:Carbon; D004396:Coloring Agents; D005260:Female; D006801:Humans; D008297:Male; D009407:Nerve Block / Q000379:methods*; D010159:Palate / Q000033:anatomy & histology / Q000098:blood supply / Q000294:innervation*; D018084:Ultrasonography, Interventional / Q000379:methods*; D055815:Young Adult
chemical_list: D004396:Coloring Agents; C028433:chinese ink; D002244:Carbon