Sphenopalatine Ganglion Block

Written by anaesthesianews

The sphenopalatine ganglion is an extracranial parasympathetic ganglion found within the pterygopalatine fossa of the skull.

The role of the sphenopalatine ganglion (SPG) in the pathogenesis of pain and its use was first described as sphenopalatine neuralgia by Sluder in 1908. He described sphenopalatine neuralgia as a unilateral facial pain symptom complex with associated neuralgic, motor, sensory, and gustatory manifestations. Today, blockade of the sphenopalatine ganglion is utilized to treat a number of painful conditions

The maxillary branch of the trigeminal nerve passes through the foramen rotundum, which is located along the superolateral aspect of the pterygopalatine fossa. The SPG is “suspended” from the maxillary nerve via the pterygopalatine nerves. Sensory fibers arising from the maxillary nerve travel through the SPG, providing sensory innervation to the nasal membranes, soft palate, and parts of the pharynx.

Indications for SPGB based on the highest level of evidence and grade of recommendation are as follows:

  • Cluster headache: 2b, B
  • Second-division trigeminal neuralgia: 2b, B
  • To help reduce the need for analgesics after endoscopic sinus surgery: 1b, B
  • Migraine headache: 2b, B

The pharmacologic agents frequently used for sphenopalatine ganglion block are local anesthetics (4% cocaine, 2% to 4% lidocaine, or 0.5% bupivacaine), depot steroids, or 6% phenol.

For the intranasal approach, a cotton tip applicator or catheter is needed. There are 3 approved SPGB devices.

Transnasal Topical Approach:

  • The patient is placed in the supine position with the cervical spine extended.
  • The measurement of the distance from the opening of the nares to the mandibular notch directly below the zygoma can be used to estimate the depth of cotton-tipped applicator advancement needed.
  • The cotton-tipped applicator is soaked in local anesthetic (viscous lidocaine 4%)
  • The cotton-tipped applicator is advanced into the nares parallel to the zygoma with the tip angled laterally until it lays on the nasopharyngeal mucosa posterior to the middle nasal turbinate.
  • A second applicator may be placed slightly posterior and superior to the initial applicator.
  • A response is typically seen in 5 to 10 minutes. However, the applicator(s) may be left in position for 30 minutes.

Transnasal Injection Approach:

  • The patient is placed in the supine position with the cervical spine extended.
  • A cotton-tipped applicator soaked in local anesthetic is advanced along the superior border of the middle turbinate. It is stopped when the posterior wall of the nasopharynx is reached. Alternatively, a small about of viscous lidocaine can be instilled into the nare(s), after which the patient inhales briskly to draw the lidocaine toward the posterior nasopharynx.
  • The chosen SPGB device (The SphenoCath, Allevio SPG Nerve Block Catheter, or Tx360 Nasal Injector) is then advanced into the ipsilateral nare.
  • Contrast can be injected under fluoroscopy to visualize needle tip placement.
  • Once the catheter tip is in place, the inner catheter is advanced to administer local anesthetic.
  • The patient should be instructed to remain in the same position for 10 minutes.

For the infra-zygomatic approach, a 10 cm curved blunt 20 or 22 gauge needle is preferred. Alternatively, a 22 or 25-gauge 3.5-inch short-bevel needle with the distal tip bent to a 15-degree angle may be used.

Infrazygomatic Approach:

Fluoroscopy or computed tomography (CT) is recommended for patient safety and improved chance of direct delivery of local anesthetic to the SPG.

  • The patient is placed in the supine position.
  • Apply sterile prepping and drape to the appropriate side of the face
  • Obtain a lateral fluoroscopic view of the face using a C-arm by superimposing the mandibular rami on top of one another
  • Anesthetize the skin above the mandibular notch
  • A 10 cm curved blunt 20 or 22-gauge needle is preferred. Alternatively, a 22 or 25-gauge 3.5-inch short-bevel needle with the distal tip bent to a 15-degree angle may be used.
  • Advance the needle in a superior and medial direction toward the pterygopalatine fossa under fluoroscopy.
  • An intermittent anteroposterior (AP) view should be obtained to assess needle depth.
  • Needle tip advancement should terminate immediately adjacent to the ipsilateral nasal wall.
  • 0.5-1 mL of nonionic, water-soluble contrast should be injected under continuous fluoroscopy to rule out intravascular uptake and intranasal spread.
  • Once proper needle placement is confirmed, 1 to 2 mL of local anesthetics, such as 1 to 2% lidocaine or 0.25% bupivacaine with or without corticosteroids, is injected.

Transoral Approach

A curved dental needle passes through the greater palatine foramen (GPF) in the posterior portion of the hard palate. This should be just medial to the gum line opposite the third molar tooth to reach the superior aspect of the pterygopalatine fossa.

Advantages: Provides more direct access to the sphenopalatine ganglia.

Disadvantages: Needle-based invasive approach, technically challenging, exhibits the greatest complications, and most patient discomfort, and is unpredictable with regards to ensuring proper anesthetic placement.

Recently, the sphenopalatine ganglion block has been successfully used in patients with PDPHs, although fewer patients were offered this block.

Ref:

Alexander CE, Dua A. Sphenopalatine Ganglion Block. [Updated 2022 Nov 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.

Nair AS, Rayani BK. Sphenopalatine ganglion block for relieving postdural puncture headache: technique and mechanism of action of block with a narrative review of efficacy. Korean J Pain. 2017 Apr;30(2):93-97.

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