This is an interesting study (abstract below) where they actually measured the distance from the nasal mucosa to the Sphenopalatine Ganglion. They found that the average distance was 6.77 mm.
In dentistry it is common for infiltration to go thru far more than 6. 7 mm of bone and tissue. The authors of this study concluded that it challenges the assumption of nasal SPG blockd effectiveness. These are just a few videos of patients successfully treated with SPG Blocks: https://www.youtube.com/playlist?list=PL5ERlVdJLdtlk8PbufsI0l_MzHo4oOb6g
It would be extremely interesting to repeat this study on patients who find nasal SPG Blocks successful and and study them in the same fashion to determine the distance from nasal mucosa.
Byrd, back in 1930 reported on 10,000 Sphenopalatine Ganglion Blocks on over 2000 patients with very high success and only 20 with any adverse (temporary) side effects. He reported success with a wide variety of disorders.
Regardless of the measurement the therapy is very successful. In 1986 56 years after the Byrd study the book “Miracles on Park Avenue” described the practice of Dr Milton Reder whose entire practice was based on SPG Blocks. Dr Reder utilized cocaine that very rapidly diffuses across the tissues. I prefer Lidocaine but the nasal cathers I utilize give a great deal of time for Lidocaine diffusion.
Regardless, some patients feel almost instananeous relief.
I originally utilized Cocaine solution and Dr Reder later switched to Lidocaine as well.
Measurement and implications of the distance between the sphenopalatine ganglion and nasal mucosa: a neuroimaging study.
Abstract
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.
KEYWORDS:
Block; Intranasal; Local anaesthetics; Pterygopalatine ganglion; Sphenopalatine ganglion