Newsletter Library: ANC March Newsletter

Trigeminal Neuralgia #2; March 08.

Trigeminal neuralgia (TN), tic douloureux, is one of the most painful conditions known to mainkind. The pain is in the distribution of one of the branches of the trigeminal or 5th cranial nerve.

History

• Earliest description in second century AD
• First full description by John Fothergill in 1773 (TN also called Fothergill’s Disease)
• French surgeon Nicholas Andre coined “tic douloureux” (painful twitch) in 1756.

Anatomy

• Usually due to an arterial loop of the superior cerebellar artery distorting and compressing the trigeminal nerve just proximal to its ganglion as the nerve root exits the brainstem.

• This compression results in some damage to the nerve root entry zone over time and ultimately can lead to the severe paroxysms of pain in one of the branches of the trigeminal nerve.

Diagnosis

• Clinical diagnosis solely based on patients history
• There are no diagnostic tests or imaging studies

Classic Symptoms diagnostic of trigeminal neuralgia:

• Unilateral facial pain confined to one or more branches of the Vth cranial nerve
• V1- ophthalmic branch innervates the upper part of the face and periorbital area including the cornea; V2- the maxillary branch innervates the mid part of the face over the cheek bones; V3- mandibular branch innervates the lower part of the face over the mandible.
• Episodic in nature lasting seconds to a couple of minutes; if episodes of pain are occurring frequently enough pain may seem continuous but it is important to distinguish this from truly continuous facial pain. If truly continuous this is not consistent with trigeminal neuralgia but rather atypical facial pain.
• Described as shock like or stabs of electricity in the face
• Usually triggered by some event such as swallowing or shaving or wind blowing on the face
• Often associated with “trigger points” on the face that when touched elicit the pain
• Usually lasting just seconds but may occur with such frequency that it may seem continuous to the patient
• Episodes typically come and go and fluctuate in frequency and severity but are usually progressive in nature over time
• Lapses of time occur where there is no pain interspersed with bouts of frequent severe pain
• So debilitating that patients may avoid eating or shaving etc that may elicit the pain. It can be so miserable as to cause mental incapacitation.
• Patients are so desperate to end the pain that often this pain leads to desperation and very commonly statements that they would rather die than continue to suffer this pain
• Usually occurs in patients over 50 years and in women slightly more than men
• If in younger years and if bilateral strongly suspect Multiple Sclerosis
• More than one branch may be affected but if bilateral it is most likely related to an underlying disorder of the brainstem such as multiple sclerosis.

Treatment of Trigeminal Neuralgia

• First and foremost is to make sure that the diagnosis is firmly established by the careful history and physical exam. A high resolution MRI of the brain should be performed to r/o other etiologies. Usually the MRI in cases of idiopathic trigeminal neuralgia is normal.
• Medical management with Tegretol and/or other neuroleptic medications (dilantin, neurotin, lyrica) should be tried as the first treatment option in most cases. Usually patients will respond to medical management but not uncommonly the medications will either cease to be effective or cause adverse side effects requiring the consideration of other options.
• For medical management failures, treatment options are either nerve destructive procedures or nerve decompression surgery.
• Destructive procedures work by purposefully damaging a portion of the nerve in hopes that this will interrupt the pain pathway. These inevitably leave numbness in a part of the face that is innervated by the area damaged. It can also lead to a painful syndrome worse than trigeminal neuralgia itself called anesthesia dolorosa in some cases. Therefore we recommend decompression surgery in most cases of healthy patients who fail medical treatment. The literature suggests that these procedures have a higher rate of recurrence and failure than does decompression surgery.
• Radiosurgery is the use of radiation therapy via a highly focused computerized procedure to damage a part of the trigeminal pathway. It has the above concerns as well as a delay of a couple of months until relief may be achieved.
• Percutaneous Rhizotomy, Glycerol Injection and Balloon compression are the most common of the percutaneous destructive procedures and are discussed above.
• Decompression Craniotomy Surgery via the Microvascular Decompression (MVD) is the gold standard of the surgical treatment options. It involves micorosurgically displacing the causative agent, usually an arterial loop of the superior cerebellar artery, away from the nerve and placing a piece of felt-like sponge material between the nerve and arterial loop to attempt to keep them separated. This operation has the highest success rate of all treatment options with the lowest recurrence rate. Nevertheless, there is still about a 10-12 percent chance of recurrence even if properly done and with a very good initial response. If recurrence occurs, one can start over with medical management or use any of the above non-medical options. If recurrent surgery is done, we will usually section a small part of the nerve as well. In our experience, surgery has been very successful and has had a low incidence of complications and recurrence rate. All patients in our series have reported significant improvement/resolution and most were able to get off all neuroleptic medications. Even those few that have recurred had an initial excellent response and to date those that recurred have responded to subsequent treatment. The prognosis of surgically treated cases has been excellent.

Should you have a patient you suspect of having Trigeminal Neuralgia or should you have it yourself, we will be happy to see, evaluate and manage this condition.

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