|Year : 2015 | Volume
| Issue : 5 | Page : 359-364
|Maxillary nerve block via the greater palatine canal: An old technique revisited
Georges Aoun1, Ibrahim Zaarour2, Sayde Sokhn3, Ibrahim Nasseh3
1 Department of Oral Pathology and Diagnosis; Department of Fundamental Sciences, School of Dentistry, Lebanese University, Beirut, Lebanon
2 Department of Oral Pathology and Diagnosis, School of Dentistry, Lebanese University, Beirut, Lebanon
3 Department of Dentomaxillofacial Radiology and Imaging, School of Dentistry, Lebanese University, Beirut, Lebanon
|Date of Web Publication||22-Sep-2015|
Department of Oral Pathology and Diagnosis and Fundamental Sciences, School of Dentistry, Lebanese University, Beirut
Source of Support: Nil., Conflict of Interest: There are no conflicts of interest.
| Abstract|| |
Background: Maxillary nerve block through the greater palatine canal is rarely adopted by dental practitioners due to lack of experience in the technique at hand which may lead into several complications. Nevertheless, it is an excellent method to achieve profound anesthesia in the maxilla. This review focuses on the anatomy as well as the indications, contraindications, and complications associated with this technique. Materials and Methods: A literature search was performed using the scientific databases (PubMed and Google Scholar) for articles published up to December 2014 in English, using the key words "maxillary nerve block via the greater palatine canal." A total of 34 references met the inclusion criteria for this review and were selected.Conclusion Block of the maxillary nerve through the greater palatine canal is a useful technique providing profound anesthesia in the hemi-maxilla, if practiced properly.
Keywords: Anesthesia, cone beam computed tomography, greater palatine canal, greater palatine foramen, maxillary nerve block, pterygopalatine fossa
|How to cite this article:|
Aoun G, Zaarour I, Sokhn S, Nasseh I. Maxillary nerve block via the greater palatine canal: An old technique revisited. J Int Soc Prevent Communit Dent 2015;5:359-64
|How to cite this URL:|
Aoun G, Zaarour I, Sokhn S, Nasseh I. Maxillary nerve block via the greater palatine canal: An old technique revisited. J Int Soc Prevent Communit Dent [serial online] 2015 [cited 2019 Jul 19];5:359-64. Available from: http://www.jispcd.org/text.asp?2015/5/5/359/165930
The greater palatine canal (GPC) transmits the greater palatine nerve [branch of the pterygopalatine ganglion that carries both general sensory fibers from the maxillary nerve (V2) and parasympathetic fibers from the nerve of the pterygoid canal] and the descending palatine artery (branch of the maxillary artery) from the pterygopalatine fossa (PPF) to the oral cavity through its lower orifice, the greater palatine foramen (GPF). Blocking of the V2 through the GPC is an old technique, which was described for thefirst time in 1917 by Nevin. It is one of two intraoral approaches, the other being the high tuberosity technique, to administer local anesthesia to the PPF in order to anesthetize the maxillary division of the trigeminal nerve. With time, it lost its interest due to the numerous complications (diplopia, ptosis, infraorbital nerve injury, etc.) resulting from improper operation, mostly due to the poor knowledge of the region's anatomy such as GPF location and GPC length.,, However, this technique consists of a single injection resulting in an anesthetic effect to the entire hemi-maxilla, including teeth, palatal and gingival mucosa, skin of the midface, maxillary sinus, and nasal cavity. Silverman, Wong and Sved, and many other authors have tried to revise this technique and even modify it in order to minimize the complications that can occur during and/or post procedure.
Among these modifications are the use of new palatal landmarks to enable consistent canal location, an increase in the needle/maxillary occlusal angle from 45° to 60°, and utilization of standard dental syringe.
The aim of this article is to review the technique of the V2 block through the GPC from an anatomic point of view, its indications, contraindications, and complications, and to highlight the advantages presented by the cone beam computed tomography (CBCT) technique in observing the exact pathway of the GPC in order to increase the success of the technique and decrease any potential complications. Literature was retrieved through databases including PubMed and Google Scholar.
V2 is the second of the three branches of the trigeminal nerve, the fifth (V) cranial nerve. Purely sensory, it leaves the skull via the foramen rotundum opening directly into the posterior wall of the PPF.
The PPF, located between the maxilla, sphenoid, and palatine bones, is a bilateral, inversed, pyramidal-shaped structure extending from the infratemporal fossa to the nasal cavity via the sphenopalatine foramen.
Its small size combined with the numerous structures that traffic through makes the PPF a complex region.
Beside its communication with the middle cranial fossa through the foramen rotundum (and the pterygoid canal also known as vidian canal), the PPF communicates with the following:,
| Introduction|| |
These communications transmit blood vessels and nerves between these regions.
The openings between the PPF and other regions, and the nerve and vessels passing through are summarized in [Table 1].
- The infratemporal fossa (via the pterygomaxillary fissure)
- The nasopharynx (via the pharyngeal canal)
- The nasal cavity (via the sphenopalatine foramen)
- The orbit (via the infraorbital fissure)
- The oral cavity (via the GPC).
After leaving the skull through the foramen rotundum, the V2 crosses the PPF giving off a number of branches (infraorbital nerve, zygomatic nerve, nasopalatine nerve, superior alveolar nerves, pharyngeal nerve, and palatine nerves), inclines laterally on the back of the maxilla, traverses the infraorbital groove and canal, and opens through the infraorbital foramen. There, it becomes the infraorbital nerve, a terminal branch, and gives lower eyelid, nasal and labial branches.
In the PPF, the greater palatine nerve leaves V2, crosses the GPC located in the thickness of the lateral wall of the nasal cavities, emerges through the GPF, and runs forward in a groove almost up to the incisor teeth where it communicates with the nasopalatine nerve. The latter, which is also a branch of the V2, enters the palate through the incisive foramen and innervates the anterior part of the hard palate behind the incisor teeth.
|Table 1: The openings between the PPF and other regions and the nerve and vessels passing through|
Click here to view
Knowing that the success of the technique of the V2 block through the GPC is based on knowledge of the anatomy of the palatal region, our goal in this review was to describe, based on previous studies found in the literature, the location of the GPF according to intraoral landmarks that enable the clinician to locate it in a consistently reliable manner and the average length of the GPC.
Matsuda was thefirst to describe the location of the GPF. Most textbooks locate the foramen in a general way:
| Materials and Methods|| |
For other more specialized studies, the location of the GPF was observed using many palatal landmarks such as:
- Close to the lateral palatal border 
- In the posterolateral border 
- Medial to the 3rd maxillary molar 
- Opposite to the 3rd maxillary molar.
The study of Slavkin et al. found the GPF 1–3 mm distal to the 3rd maxillary molar in adult skulls. In 1982, Westmoreland and Blanton  observed only 6% of the foramen distal to the 3rd molar and 9.7% medial to the maxillary 2nd molar. According to Ajmani, 48% of the GPF in Nigerian and 64% in Indian skulls were located medial or opposite to the maxillary 3rd molar. Saralaya and Nayak  and Chrcanovic and Custódio  concluded in their studies that 74.6% and 54.87% of the GPF, respectively, were opposite to the 3rd molar.
Some data retrieved from the literature regarding the positional variance of the GPF with respect to the maxillary molars are compared and summarized in [Table 2].
- Its relation to the maxillary molar teeth
- Its distance from the midline maxillary suture (MMS)
- Its distance from the posterior border of the hard palate (PBHP)….
As for the distance between the GPF and the MMS, it was found to be around 15 mm according to the study of Westmoreland and Blanton. Ajmani reported a distance of 15.4 mm in Nigerian skulls and a mean of 14.7 mm in Indian skulls. The same distance (14.7 mm) was reported by the study of Saralaya and Nayakand  and an average of 14.56 mm was reported by Chrcanovic and Custódio.
Concerning the mean distance of the GPF from the PBHP, it varies between 1.9 mm and 4.2 mm.,,,
Some data retrieved from the literature regarding the mean distance of the GPF from the MMS and the PBHP are compared and summarized in [Table 3].
|Table 2: Comparison of some data from the literature on the positional variance of the GPF with respect to the maxillary molars|
Click here to view
Regarding the length of the GPC, Swirzinski et al. and Sheikhi et al., in their studies based on CBCT observations, concluded that the average length of the GPC in adult population was 29 ± 3 mm (ranging from 22 to 40 mm) and 31.82 ± 1.37 mm, respectively. Tomaszewska et al. observed 1500 adult Caucasian head CT scans and found that the average length of the GPC was 31.1 ± 2.9 mm (range 15–44) mm. According to Das et al., the range of the GPC length is located between 27 and 44 mm with a mean of 32 mm.
Some data retrieved from the literature regarding the length of the GPC are compared and summarized in [Table 4].
|Table 3: Comparison of some data from the literature on the mean distance of the GPF from the MMS and the PBHP|
Click here to view
Clinically, the GPF is located by applying pressure on a cotton swab at the junction of the hard palate and the maxillary alveolar process until it falls into the depression of the GPF.
As mentioned above, the GPF is most often located distal to the 2nd maxillary molar and its average length is 32 mm., Knowing that long canals could lead to lack of anesthesia and, conversely, short ones could have a higher occurrence of complications if the standard needle is used, a CBCT is indicated prior to the procedure to analyze the GPC anatomy, mainly its localization and length [Figure 1] and [Figure 2].
|Table 4: Comparison of some data from the literaturte on the length of GPC|
Click here to view
Once the GPF is identified, at the most a 27 G needle on a dental syringe is inserted perpendicularly until bone contact and 0.5 ml of local anesthetic is deposited to provide local anesthesia in the area to be injected. After waiting for 3–5 min, the needle is introduced slowly at an angle of 45° to the long axis of the hard palate in the canal to nearly a depth of 32 mm for adults.
Exactly 1.8 ml of local anesthetic is injected without any compression, in order to avoid the risk of tissue necrosis., Maximum anesthesia effect is obtained in 5–15 min.
Aspiration is necessary before injection; if blood (needle is in a vessel) or bubbles (needle is in the nasopharynx) are aspirated, the needle is removed, redirected, and reinserted at a different angle.
Indications and contraindications
Maxillary nerve block via the GPC achieves anesthesia of the following:
|Figure 1: Sagittal view showing the GPC; the arrows show the superior and inferior openings of the canal|
Click here to view
Furthermore, this technique is used for the diagnosis and treatment of chronic oral and maxillofacial pain syndromes.
Jonas et al. successfully treated posterior epistaxis (nosebleeds) with endoscopic sphenopalatine artery ligation technique by infiltration of local anesthesia with vasoconstrictors via the GPC in the PPF. This process can cause vasospasm of the terminal (third) part of the maxillary artery, decreasing the blood flow in its terminal branch and thus facilitating the ligation procedure.
As for the contraindications, the following can be mentioned:
- The hemi-maxilla including teeth, bone, and soft tissue (this effect could be useful for surgical procedures in this region),,
- The skin of the midface (for patients with maxillary trauma)
- The nasal cavity and sinus (during endoscopic sinus surgery and septorhinoplasty).,,
Complications can be as follows:
- The presence of infection in the foramen region, which can lead to the infection spreading in the PPF 
- The presence of systemic coagulation defect inducing bleeding in case of vascular injury 
- Difficulties to locate the GPF or negotiate the GPC.,
Related to the local anesthetic:
- Toxicity caused by a large quantity of the anesthetic or an intravascular injection. The toxicity may develop minimal to moderate symptoms such as anxiety, numbness, dizziness, weakness, and tremors. Sometimes, more severe symptoms like central nervous system or cardiovascular collapse may occur
- Allergic reaction caused generally by an ester group local anesthetic and/or the preservatives added to it (methylparaben, sodium metabisulfite, etc.)
- Related to the technique itself:
More serious complications can occur such as:
Persistent paresthesia and numbness due to V2 trauma or local hematoma formation
- Diplopia (double vision), the most common (35.6%) complication, resulting from the accidental block of the abducens nerve (the 6th cranial nerve) innervating the lateral rectus muscle, one of the extraocular muscles, by dissemination of the anesthetic through the superior orbital fissure ,,
- Transient ophthalmoplegia by anesthetizing the extraocular muscles of the eye 
- Ptosis (upper eyelid paralysis) due to anesthesia of the superior division of the oculomotor nerve (the 3rd cranial nerve) responsible of the innervation of the upper eyelid levator muscle.
- Infraorbital nerve injury and/or injection (accidental penetration of the orbit)
- Neural tissue damage
- Temporary blindness from vasoconstriction of the ophthalmic artery or block of the optic nerve
- Unconsciousness from intracranial injection (diffusion of the anesthetic via the foramen rotundum).
The maxillary nerve block via the GPC was revisited regarding its implementation by a dental practitioner. The technique is deemed advantageous in terms of achieving profound anesthesia of the hemi-maxilla, especially for oral surgeons; however, due to the possibility of rare but potentially serious complications, the said technique should only be performed by proficient and qualified personnel with all necessary equipments at hand. This being said, it is to be noted that a CBCT is imperative to analyze the GPC anatomy, mainly its localization and length.
| Conclusion|| |
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Nevin M, Puterbaugh PG. Conduction, Infiltration and General Anesthesia in Dentistry. 4th
ed. New York: DentItemsInterest Publishing co.; 1938. p. 140.
Lepere A. Maxillary nerve block via the greater palatine canal: New look at an old technique. Anesth PainControlDent 1993;2:195-7.
Silverman SL. A new and more accurate technique for injecting the superior maxillary division. J AmMedAssoc 1923;81:112.
Wong JD, Sved AM. Maxillary nerve block anaesthesia via the greater palatine canal: A modified technique and case reports. AustDentJ 1991;36:15-21.
Hawkins JM, Isen D. Maxillary nerve block: The pterygopalatine canal approach. J CalifDentAssoc 1998;26:658-64.
Erdogan N, Unur E, Baykara M. CT anatomy of pterygopalatine fossa and its communications: A pictorial review. Comput Med Imaging Graph 2003;27:481-7.
Gray H, Standring S, Ellis H, Berkovitz BKB. Gray'sAnatomy: The anatomical Basis ofClinical Practice New York: Edinburgh, Elsevier Churchill Livingstone; 2005. p. 1627.
Carpentier P. Trigeminal sensory pathways: A guide for anesthesia. Actual Odonto-Stomatol 1992;179:453-67.
Standring S, Ellis H, Healy JC, et al
. Oral cavity. Gray's Anatomy: The Anatomical Basis of Clinical Practice. In: Standring S, editor. 39th
ed. London: Elsevier, Churchill Livingstone; 2005. p. 584.
Matsuda Y. Location of the dental foramina in human skulls from statistical observations. IntJOrthodOralSurgRadiogra 1927;13:299-305.
Williams PL, Warwick R, Dyson M, Bannster H. Gray'sAnatomy. 38th
ed. London: Longmans; 1995. p. 187-91.
Gardner E, Gray DJ, O'Rahilly R. Anatomy. 4th
ed. Philadelphia: WB Saunders; 1975. p. 997.
Moore KL. Clinically Oriented Anatomy. Baltimore: Williams and Wilkins; 1980. p. 1004.
Romanes GJ. Cunningham'sTextbookofAnatomy. 12th
ed. New York: Oxford University Press; 1981. p. 166.
Slavkin HC, Canter MR, Canter SR. An anatomic study of the pterygomaxillary region in the craniums of infants and children. Oral Surg Oral Med Oral Pathol 1996;21:225-35.
Westmoreland EE, Blanton PL. An analysis of the variations in position of the greater palatine foramen in the adult human skull. AnatRec 1982;204:383-8.
Ajmani ML. Anatomical variation in position of the greater palatine foramen in the adult human skull. J Anat 1994;184:635-7.
Saralaya V, Nayak SR. The relative position of the greater palatine foramen in dry Indian skulls. SingaporeMedJ 2007;48:1143-6.
Chrcanovic BR, Custódio AL. Anatomical variation in the position of the greater palatine foramen. J OralSci 2010;52:109-13.
Swirzinski KH, Edwards PC, Saini TS, Norton NS. Length and geometric patterns of the greater palatine canal observed in cone beam computed tomography. Int J Dent 2010;2010. pii: 292753.
Sheikhi M, Zamaninaser A, Jalalian F. Length and anatomic routes of the greater palatine canal as observed by cone beam computed tomography. Dent Res J (Isfahan) 2013;10:155-61.
Tomaszewska IM, Kmiotek EK, Pena IZ, Sredniawa M, Czyzowska K, Chrzan R, et al.
Computed tomography morphometric analysis of the greater palatine canal: A study of 1,500 head CT scans and a systematic review of literature. Anat Sci Int 2014; Dec 3. doi: 10.1007/s12565-014-0263-9.
Das S, Kim D, Cannon TY, Ebert JR, Senior BA. High-resolution computed tomography analysis of the greater palatine canal. AmJRhinol 2006;20:603-8.
Nish LA, Pynn BR, Holmes HI, Young ER. Maxillary nerve block: A case report and review of intraoral technique. J CanDentAssoc 1995;61:305-10.
Malamed SF, Trieger N. Intraoral maxillary nerve block: An anatomical and clinical study. AnesthProg 1983;30:44-8.
Mahoney PM. Maxillary nerve block. AnesthProg 1977;24:47-9.
Sved AM, Wong JD, Donkor P, Horan J, Rix L, Curtin J, et al
. Complications associated with maxillary nerve block anesthesia via the greater palatine canal. AustDentJ 1992;37:340-5.
Methathrathip D, Apinhasmit W, Chompoopong S, Lertsirithong A, Ariyawatkul T, Sangvichien S, et al
. Anatomy of greater palatine foramen and canal and pterygopalatine fossa in Thais: Considerations for maxillary nerve block. SurgRadiolAnat 2005;27:511-6.
Wormald PJ, Athanasiadis T, Rees G, Robinson S. An evaluation of effect of pterygopalatine fossa injection with local anaesthetic and adrenalin in the control of nasal bleeding during endoscopic sinus surgery. AmJRhinol 2005;19:288-92.
Wormald PJ, Wee DT, van Hasselt CA. Endoscopic ligation of the sphenopalatine artery for refractory posterior epistaxis. AmJRhinol 2000;14:261-4.
Jonas N, Viani L, Walsh M. Sphenopalatine artery ligation under local anesthesia: A report of two cases and review of the literature. LocalRegAnesth 2010;3:1-4.
Sharma NA, Garud RS. Greater palatine foramen-key to successful hemimaxillary anaesthesia: A morphometric study and report of a rare aberration. SingaporeMedJ 2013;54:152-9.
Poore TE, Carney MT. Maxillary nerve block: A useful technique. J OralSurg 1973;31:749-54.
Douglas R, Wormald PJ. Pterygopalatine fossa infiltration through the greater palatine foramen: Where to bend the needle. Laryngoscope 2006;116:1255-7.
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]
|This article has been cited by|
||Optimization of the Surgical Field in Endoscopic Sinus Surgery: an Evidence-Based Approach
| ||Saad Alsaleh,Jamil Manji,Amin Javer |
| ||Current Allergy and Asthma Reports. 2019; 19(1) |
|[Pubmed] | [DOI]|
||Radio-Morphometric Evaluation of Greater Palatine Canal and Pterygopalatine Fossa Component
| ||Onurcem Duruel,Varun Kulkarni,Emel Tugba Ataman-Duruel,Melek Didem Tözüm,Tolga Fikret Tözüm |
| ||Journal of Craniofacial Surgery. 2019; 30(3): 863 |
|[Pubmed] | [DOI]|
||A Cadaveric Study of Ultrasound-Guided Maxillary Nerve Block Via the Pterygopalatine Fossa
| ||Wirinaree Kampitak,Tanvaa Tansatit,Yasuyuki Shibata |
| ||Regional Anesthesia and Pain Medicine. 2018; 43(6): 625 |
|[Pubmed] | [DOI]|
||Morphological observation and CBCT of the bony canal structure of the groove and the location of blood vessels and nerves in the palatine of elderly human cadavers
| ||Yoko Miwa,Rieko Asaumi,Taisuke Kawai,Yuuki Maeda,Iwao Sato |
| ||Surgical and Radiologic Anatomy. 2017; |
|[Pubmed] | [DOI]|
||Radioanatomic Study of the Greater Palatine Canal Relevant to Endoscopic Endonasal Surgical Landmarks
| ||Noel Ayoub,Andrew Thamboo,Peter H. Hwang,Evan S. Walgama |
| ||Otolaryngology-Head and Neck Surgery. 2017; 157(4): 731 |
|[Pubmed] | [DOI]|
||Radiological Localization of Greater Palatine Foramen Using Multiple Anatomical Landmarks
| ||Viveka S |
| ||MOJ Anatomy & Physiology. 2016; 2(7) |
|[Pubmed] | [DOI]|
||Blanching of facial skin after infiltration of local anaesthetic: an unusual complication of inadvertent intra-arterial injection
| ||Robert Stuart McCormick,James R. Adams |
| ||British Journal of Oral and Maxillofacial Surgery. 2016; |
|[Pubmed] | [DOI]|
| Article Access Statistics|
| Viewed||3028 |
| Printed||20 |
| Emailed||0 |
| PDF Downloaded||182 |
| Comments ||[Add] |
| Cited by others ||7 |