Trigeminal Neuralgia

CHAPTER 18 TRIGEMINAL NEURALGIA



Robert A. Duarte, MD, Charles E. Argoff, MD




1. What is the term tic douloureux?


In French, tic means spasm and douloureux means painful. Tic douloureux is synonymous with trigeminal neuralgia.



2. What is pretrigeminal neuralgia?


Pretrigeminal neuralgia is a rare, prodromal pain that occurs prior to the onset of trigeminal neuralgia. Typically, the pain is described as a dull toothache. Physical examination and imaging studies are essentially unremarkable. Clinically, patients may go to the dentist and may undergo unnecessary dental procedures. Treatment often consists of trials of anticonvulsants and/or baclofen.



3. What are the divisions of the trigeminal nerve?


The three main divisions of the trigeminal nerve are the ophthalmic (V1), maxillary (V2), and mandibular (V3), which supply sensation to the face.


The ophthalmic division supplies sensation from the eyebrows to the coronal suture. However, the sensory distribution does not stop at the hairline but at the corona, which may help in differentiating anatomic lesions from factitious illness, because patients feigning sensory loss usually make the divide at the hairline.


Innervation of the cornea is divided, being supplied by V1 in its upper half and V2 in its lower half. The cheek bones and the inside of the nares are supplied by V2.


The mandibular branch supplies the lower jaw. However, the angle of the jaw is supplied by a cervical root rather than by the trigeminal nerve. Again, this helps in anatomic differentiation.



4. What are the functions of the trigeminal nerve?


The motor functions of the trigeminal nerve include supplying the muscles of mastication. These are the temporalis, masseters, and pterygoids. The first two are involved in vertical closing of the jaw, and the third is involved in lateral motion of the jaw (grinding).



5. Name the exit (or entry) foramina for the branches of the trigeminal nerve




image Ophthalmic branch: through the superior orbital fissure, along with cranial nerves III, IV, and VI, and the ophthalmic vein


image Maxillary branch: through the foramen rotundum in the base of the skull


image Mandibular branch: through the foramen ovale



6. What is the difference between primary and secondary trigeminal neuralgia?


Primary or idiopathic trigeminal neuralgia implies no known structural cause for the pain (even though an aberrant vessel may be found in some cases). In secondary or symptomatic trigeminal neuralgia, pain is caused by either compression or demyelination. The clinical pain syndrome is indistinguishable. However, secondary syndromes usually involve dysfunction of the trigeminal nerve between attacks. This may take the form of sensory loss in one of the distributions of the nerve or paresis of one of the muscles of mastication.



7. What are the clinical characteristics of trigeminal neuralgia?


Clinically, patients with trigeminal neuralgia describe a sharp, shooting, lightninglike or electrical sensation that typically lasts seconds to minutes in the distribution of one or more branches of the trigeminal nerve. The V2 to V3 distribution is the most common location, followed by V2; the ophthalmic division is involved in only 5% of cases. Attacks of trigeminal neuralgia are severely painful, often are followed by a lucid (pain-free) interval. In the idiopathic form, the pain is unilateral, and the physical examination is unremarkable without objective sensory or motor dysfunction. In the symptomatic form, the pain can be bilateral (in up to 4% of cases), and there may be some objective sensory loss.



8. Describe the natural history of trigeminal neuralgia


In idiopathic trigeminal neuralgia, onset is most likely after the age of 50. Patients below the age of 40 with true or symptomatic trigeminal neuralgia should be investigated for an underlying demyelinating lesion. Other structural pathology may include an underlying tumor (e.g., meningioma, ependymoma). Similarly, if there is bilateral involvement, suspect multiple sclerosis.


The disease usually follows an exacerbating but remitting course. Over 50% of individuals will have at least a 6-month remission during their lifetime. There may be months or years when the patient is pain free. Therefore, drug holidays should be attempted to see if the patient is indeed responding to the drug or simply having a remission of the disease. In some patients, the attacks become more frequent and may be nearly continuous.

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Jun 14, 2016 | Posted by in PAIN MEDICINE | Comments Off on Trigeminal Neuralgia

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