Chapter 17: Trigeminal Ganglion and Nerve Block

INTRODUCTION

Blockade of the trigeminal ganglion and/or its peripheral branches is a useful technique that can benefit patients who have refractory facial pain and certain types of headaches that have not responded to conservative measures. The trigeminal ganglion was first described by the anatomist Johann Gasser and blockade of the ganglion was first described by Hartel in 1912.

INDICATIONS

Indications for blockade of the ganglion and/or its peripheral branches include:

• Tic douloureux (trigeminal neuralgia)

• Atypical trigeminal neuralgia

• Chronic, intractable cluster headaches^{1, 2, 3, 4, and 5}

• Persistent idiopathic facial pain

• Herpes zoster

• Palliation of cancer-related pain

RELEVANT ANATOMY

The trigeminal ganglion resides in the middle cranial fossa.^{6, 7, and 8} The ganglion is formed by the fusion of a series of cell bodies that originate at the mid-pontine level of the brainstem. It is situated in a fold of dura mater that forms an invagination around the posterior two-thirds of the ganglion. This region is referred to as the Meckel cavity and contains cerebrospinal fluid.

• The ganglion is bound medially by the cavernous sinus and optic and trochlear nerves; superiorly by the inferior surface of the temporal lobe of the brain; and posteriorly by the brain stem. Access to the ganglion requires passage of the block needle through foramen ovale.

• The ganglion is situated in the posterior part of the sphenoid bone, posterolateral to foramen rotundum.

• Within foramen ovale lies the mandibular nerve, accessory meningeal artery and the lesser petrosal nerve.

• The ganglion has three major divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3). The ophthalmic division is located dorsally, the maxillary branch intermediate, and the mandibular branch ventrally. This arrangement is important when a thermal rhizotomy is being considered.

• The ophthalmic division leaves the ganglion and passes into the orbit through the superior orbital fissure. It further divides into the supraorbital, supratrochlear, and nasociliary nerves which innervate the forehead and the nose.⁸

• The maxillary division exits the middle cranial fossa via foramen rotundum, crosses the pterygopalatine fossa, and enters the orbit through the inferior orbital fissure. Branches include the infraorbital, superior alveolar, palatine, and zygomatic nerves which carry sensory information from the maxilla and overlying skin, the nasal cavity, palate, nasopharynx and meninges of the anterior and middle cranial fossa.⁸

• The mandibular division exits through foramen ovale and divides into the buccal, lingual, inferior alveolar, and auriculotemporal nerves. These nerves carry sensory input from the buccal region, the side of the head and scalp, and the lower jaw including teeth, gums, anterior two-thirds of the tongue, chin, and lower lip.⁸

• The motor component of V3 innervates the masseter, temporalis, and medial and lateral pterygoids.

• The ganglion interferes with the autonomic nervous system via the ciliary, sphenopalatine, otic, and submaxillary ganglia. It also communicates with the oculomotor, facial, and ...