Measurement and implications of the distance between the sphenopalatine ganglion and nasal mucosa: a neuroimaging study

Joan Crespi, Daniel Bratbak, David Dodick, Manjit Matharu, Kent Are Jamtøy, Irina Aschehoug, Erling Tronvik

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Background: Historical reports describe the sphenopalatine ganglion (SPG) as positioned directly under the nasal mucosa. This is the basis for the topical intranasal administration of local anaesthetic (LA) towards the sphenopalatine foramen (SPF) which is hypothesized to diffuse a distance as short as 1 mm. Nonetheless, the SPG is located in the sphenopalatine fossa, encapsulated in connective tissue, surrounded by fat tissue and separated from the nasal cavity by a bony wall. The sphenopalatine fossa communicates with the nasal cavity through the SPF, which contains neurovascular structures packed with connective tissue and is covered by mucosa in the nasal cavity. Endoscopically the SPF does not appear open. It has hitherto not been demonstrated that LA reaches the SPG using this approach. Methods: Our group has previously identified the SPG on 3 T–MRI images merged with CT. This enabled us to measure the distance from the SPG to the nasal mucosa covering the SPF in 20 Caucasian subjects on both sides (n = 40 ganglia). This distance was measured by two physicians. Interobserver variability was evaluated using the intraclass correlation coefficient (ICC). Results: The mean distance from the SPG to the closest point of the nasal cavity directly over the mucosa covering the SPF was 6.77 mm (SD 1.75; range, 4.00–11.60). The interobserver variability was excellent (ICC 0.978; 95% CI: 0.939–0.990, p < 0.001). Conclusions: The distance between the SPG and nasal mucosa over the SPF is longer than previously assumed. These results challenge the assumption that the intranasal topical application of LA close to the SPF can passively diffuse to the SPG.

Original languageEnglish (US)
Article number14
JournalJournal of Headache and Pain
Issue number1
StatePublished - Dec 1 2018


  • Block
  • Intranasal
  • Local anaesthetics
  • Pterygopalatine ganglion
  • Sphenopalatine ganglion

ASJC Scopus subject areas

  • Clinical Neurology
  • Anesthesiology and Pain Medicine


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