Sphenopalatine Ganglion Block - Indications, Contraindications, and Techniques

Introduction

The Sphenopalatine ganglion (a collection of neuronal bodies) block (SPG) is an extracranial parasympathetic ganglion situated in the pterygopalatine fossa, which is an inverted pyramidal space also referred to as the pterygopalatine ganglion or Meckel ganglion. It contains sympathetic, parasympathetic, and sensory neurons and is the biggest ganglion outside the calvarium. It nourishes the lacrimal gland, paranasal sinuses, mucosal glands of the nasal cavity and throat, gingiva, mucous membrane, and hard palate glands. It is unaffected by emotion or movement.

The SPG, located just posterior to the middle nasal turbinate, is the sole ganglion that may reach externally through the nasal mucosa. When a nerve is stimulated by trauma, illness, or other factors, sympathetic activity can induce pain. The pain may be relieved by anesthetizing the SPG and inhibiting sympathetic activity. With varying levels of effectiveness, the SPG has been a neurological focus for treating several headaches and facial pain diseases, such as cluster headaches (CHs), atypical facial pain, trigeminal neuralgia, and migraine headaches.

What Is the Anatomic Consideration for the SPG Block?

The pterygopalatine fossa has the following borders:

1. Anterior Border - Maxillary sinus posterior wall.

2. Posterior Border - Medial pterygoid plate.

3. Superior Border - Sphenoid sinus.

4. Medial Border - Palatine bone perpendicular plate.

5. Lateral Border - Interfaces with infratemporal fossa.

It is located posterior to the middle nasal turbinate and the maxillary sinus, forming many autonomic, sensory, and motor neuronal connections.

Sensory Innervation: The trigeminal nerve's maxillary branch travels via the foramen rotundum, which runs along the superolateral portion of the pterygopalatine fossa. The pterygopalatine nerves "suspend" the SPG from the maxillary nerve. Sensory nerve fibers originating from the maxillary nerve pass through the SPG, innervating the nasal membranes, soft palate, and sections of the pharynx.

Autonomic Innervation: The SPG receives sympathetic innervation from preganglionic sympathetic fibers in the upper thoracic spine, which travel along the sympathetic chain and connect with postganglionic fibers in the superior cervical sympathetic ganglion. Postganglionic fibers branch off the carotid nerves and go into the deep petrosal and vidian nerves. The SPG transports these postganglionic fibers to the lacrimal gland, nasal mucosa, and palatine mucosa. In addition, the SPG receives parasympathetic innervation from the superior salivatory nucleus of the pons.

The greater petrosal nerve comprises parasympathetic fibers that pass through the geniculate ganglion and the nervus intermedius, a branch of the facial nerve. Parasympathetic fibers synapse in the SPG. Second-order neurons then supply secretomotor function to the nasal, oral, and pharyngeal mucous membranes, lacrimal glands, and branches to the meningeal and cerebral blood vessels. Different branches form the SPG's superior posterior lateral nasal and pharyngeal nerves. The SPG is directly connected to the greater and smaller palatine nerves.

Why Is Sphenopalatine Ganglion Block Performed?

A sphenopalatine ganglion block is a quick, minimally invasive technique that uses local anesthetics to block impulses traveling through those neurons and manage facial discomfort. It is helpful in the treatment of some acute and chronic facial and headaches. SPG block could be employed as a screening tool to determine where pain signals can be disrupted.

What Are the Indications for SPG Block?

1. Second-division trigeminal neuralgia pain.

2. To assist in reducing the requirement for analgesics following endoscopic sinus surgery.

3. Headache syndromes, including hemicrania continua, trigeminal neuralgia, and dural puncture headache.

4. Complex regional pain syndrome (CRPS), intercostal neuralgia, and dysmenorrhea are intractable hiccups.

5. Temporomandibular disorder.

6. Nasal contact point headache.

7. Vasomotor rhinitis.

8. Cancer of the head or neck

What Are the Contraindications of SPG Block?

Allergies to any drugs used, anticoagulation, history of facial trauma, infection, and patient refusal are all contraindications to sphenopalatine ganglion block.

What Are the Equipment Required for SPG Block?

Local anesthetics solution Lidocaine, Bupivacaine, Cocaine, steroids, or six percent Phenol are common pharmacological drugs used for SPG block. A cotton tip brush or catheter is required for the intranasal method. Three SPGB devices have been approved. These catheters are introduced along the anterior nasal canal and superior to the middle nasal turbinate - a flexible sheath with an inner, expandable catheter with a curved tip. The Tx360 instrument is advanced inferiorly to the middle nasal turbinate after being placed. The catheter tip is positioned medially, below, and behind the target mucosa. The catheter tip's aperture is intended to direct anesthesia in a superior, lateral, and anterior orientation.

A 20 to 22-gauge needle, which is blunt and cured, is suggested for the infra-zygomatic approach. In addition, a 22 or 25-gauge 3.5-inch short-bevel needle with a distal tip bent to a 15-degree angle can also be utilized. Advanced medical imaging devices based on X-ray technologyand Iohexol, which is an intravascular iodinated X-ray contrast agent of 0.5 to 1 mL, are also required. A curved dental needle is required for the transoral technique.

How Is the Patient Prepared for SPG Block?

It is critical to determine whether the patient is on anticoagulant or antiplatelet treatment before surgery. To ensure patient safety, if the patient is on anticoagulants or antiplatelet therapy, it may be essential to consult with the patient's primary healthcare provider or cardiologist.

Warfarin-treated individuals should acquire a prothrombin time (PT) before surgery. Should obtain partial thromboplastin time (PTT) for heparin dosage before surgery. Check for the vitals before and after the procedure. The patient should be positioned supine, with the cervical spine extended.

What Are the Techniques for Sphenopalatine Ganglion Block?

Sphenopalatine ganglion block can be done transnasally, transorally, or transcutaneously.

Transnasal Topical Approach:

• The patient is positioned supine.

• Determine the distance between the entrance of the nasal passages and the mandibular notch right underneath the zygoma to determine the depth of cotton-tipped applicator advancement required.

• The cotton-tipped applicator has been immersed in a local anesthetic (viscous lidocaine 4 %).

• The cotton-tipped applicator is inserted into the nasal cavity parallel to the zygoma, with the tip-tilted laterally, until it reaches the nasopharyngeal mucosa posterior to the middle nasal turbinate.

• A second applicator might be positioned somewhat posteriorly and superior to the first one.

• A response is usually seen within five to ten minutes. However, it can keep the applicator in place for up to 30 minutes.

Transnasal Injection Approach:

• Place the patientin a supine position.

• A local anesthetic-soaked cotton-tipped applicator is pushed along the superior border of the middle turbinate. It stops when it reaches the posterior wall of the nasopharynx. Alternatively, a tiny amount of viscous lidocaine can be injected into the nasal cavity, followed by a rapid inhalation to draw the lidocaine into the posterior nasopharynx.

• The SPGB device of choice (the SphenoCath, Allevio SPG nerve block catheter, or Tx360 nasal injector) is subsequently inserted into the ipsilateral nasal cavity.

• To visualize needle tip location, contrast can be administered under fluoroscopy.

• The inner catheter is advanced after the catheter tip is in place to give local anesthesia.

• The advantage is that it is a straightforward approach with a short duration, and minimal risk of consequences such as bleeding from the nose and infection.

• The disadvantage is that it necessitates the diffusion of local anesthetic over mucosal membranes.

Transoral Approach:

• A curved dental needle is inserted through the greater palatine foramen (GPF) in the hard palate's posterior half. To access the superior aspect of the pterygopalatine fossa, position this just medial to the gum line opposing the third molar tooth.

• Advantages include improved direct access to the sphenopalatine ganglion.

• Disadvantages include needle-based invasive technique is technically challenging, has the most difficulties, causes most patient discomfort, and is uncertain when assuring practical anesthetic application.

Infrazygomatic Approach:

• Fluoroscopy or computed tomography (CT) is recommended for the patient's safety and a better chance of administering local anesthetic directly to the SPG.

• The patient is asked to lie supine.

• Apply sterile preparation to the appropriate side of the face and wrap the patient.

• Using an advanced medical imaging device based on X-ray technology, get a lateral fluoroscopic picture of the face by superimposing the mandibular rami on top of one another.

• Anesthetize the skin above the mandibular notch.

• Using a 20 to 22-gauge needle, which is blunt and cured, is best. A 22 or 25-gauge 3.5-inch short-bevel needle with a distal tip curved to a 15-degree angle can also be utilized.

• Under fluoroscopy, move the needle superiorly and medially toward the pterygopalatine fossa.

What Are the Complications of SPG Block?

• Minor side effects of sphenopalatine ganglion block are generally local. They include bleeding from the nose, temporary numbness or hypoesthesia of the nose root, pharynx, and hard palate, and lacrimation of the ipsilateral eye.

• Significant side effects are infrequent but can include infection due to poor aseptic technique and a local or retro-orbital hematoma.

Conclusion

The SPG block looks like a simple, straightforward, minimally invasive procedure that may be performed at the patient's bedside. SPG blockage requires accurate diagnosis and patient selection. Chronic headache and face pain syndromes can result in considerable impairment, reduced functioning, and increased healthcare expenses. An interdisciplinary approach to these individuals is the most beneficial, involving neurology, psychology, and pain treatment. Neurologists and headache specialists are often in charge of finding acceptable patients for surgery.