Trigeminal Neuralgia

Trigeminal neuralgia is the most common neuralgic syndrome in the elderly, with a peak incidence of 155 cases per million and a female:male ratio of 3:2. Trigeminal neuralgia is typically unilateral, but it can be bilateral in 4% of patients. It is characterized by brief paroxysms of unilateral pain, similar to a spasm or an electric shock, in the distribution of one or more divisions of the trigeminal nerve. The mandibular or maxillary branches of the nerve are most frequently involved. The pain may be provoked by stimulation of specific trigger points, or by stimuli such as washing, shaving, talking, or brushing the teeth. The pain may precipitate facial muscle spasms, hence the term tic douloureux. Between paroxysms, a sustained, deep, dull ache may be present.

Pretrigeminal neuralgia is a dull, continuous aching-type pain in the jaw. It may be provoked by pressure about the face or mouth and may evolve into true trigeminal neuralgia. These non-specific clinical features may lead to dental evaluation and procedures. Hence dental procedures may be a response to pretrigeminal neuralgia rather than a cause of trigeminal neuralgia.

The aetiology of trigeminla neuralgia varies with age. When trigeminal neuralgia begins in the twenties an thirties, causes include demyelinating disease(Multiple sclerosis), compression of the trigeminal nerve root at its exit foramen(e.g. myeloma or metastatic carcinoma of the sphenoid bone), and other mass lesions, such as meningiomas, acoustic neuroma, trigeminal neuromas, cholesteatomas, chordomas, aneurysms(especially of the basilar artery), and other vascular abnormalities.

In the elderly, trigeminal neuralgia commonly is a result of vascular compression of the trigeminal nerve due to abnormal arterial loops near the trigeminal nerve root entry zone. Vascular compression leads to demyelination and aberrant neuronal activity, which may produce sensitization in the trigeminal nucleus caudalis. Other cause of trigeminal neuralgia in the elderly are the same as in young adults, as outlind above.

The diagnosis of trigeminl neuralgia is established by its typical clinical features. The physical eaxmination is negative except for the positive trigger points. Diagnostic studies are generally normal. Impaired sensation in the distribution of th Vth nerve suggests a structural, demyelinating, or compressive trigeminal nerve lesion. The initial evaluationshoild include magnetic resonance imaging with special attention to the region of the cerebellopontine angle and the exit foramen of the trigeminal nerve.

Diagnostic Criteria

A. Paroxysmal attacks of facial or frontal pain which last a few seconds to less than 2 minutes

B. Pain has at least 4 of the following characteristics:

1. Distribution along one or more divisions of the trigeminal nerve

2. Sudden, intense, sharp, superficial, stabbing, or burning in quality

3. Pain intensity severe

4. Precipitation from trigger areas or by certain daily activities such as eating, talking, washing the face, or cleaning the teeth

5. Between paroxysms the patient is entirely asymptomatic

C. No neurologic deficit

D. Attacks are stereotyped in the individual patient

E. Exclusion of other causes of facial pain by history, physical examination, and special investigations