Neuralgia

Sunday, 20 February 2005 14:18
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Neuralgia is the term used to describe pain arising from a nerve. There are many different neuralgias which have been described in the medical literature, but I will only touch upon a few more common ones.

Neuralgias tend to be sudden, brief, intermittent severe, stabbing or lightning pains or electric shock sensations.

They are known to occur in conditions such as MS, as well as after shingles (Post-herpetic neuralgia :PHN)

TGN may be associated with difficulty in eating (thus weight loss) and depression.

Treatment of neuralgia:

Looking at the typical treatment of TGN:

The usual therapy is with an anticonvulsant such as carbamazepine or gabapentin.

Occasionally, sodium valproate may be used.

Low starting doses and gradual increases are needed to avoid adverse effects.

If using carbamazepine, 100mg twice daily is the starting dose, increasing by 100mg each week until pain control is achieved.  Maximum dose is 1.6g daily; usually 300-600mg is effective therapeutically.

Once pain control has been achieved, in cases where there has not been sustained pain (i.e. if there is an intermittent pattern of symptoms), the dose should be maintained for a month and then reduced by 100mg every 2 days.

If the pain should recur, then the dose should be increased again. Doses should be taken 30 minutes before food and a double dose can be given at night to ensure adequate levels. Around 70% of patients have relief within 24 hours. (95% within 48 hours).

Liver function tests, blood count and blood biochemistry may be monitored (baseline before treatment, then every month for 3 months, then every 6 months)

Side effects include: dizziness, drowsiness. These are more common in the elderly.

HEADACHES:I have written a separate article which deals with the general topic of headaches.

I am only including migraine headaches in this neurology-based article.

MIGRAINES:

Migraine is an episodic condition.

There are 2 main forms:

  1. Migraine without aura (?common' migraine): 75% of sufferers have this type. 5 or more attacks are needed to make a diagnosis. Attacks involve: classical one-sided headache, severe, pulsating, with associated nausea/vomiting, intolerance of bright light and loud noises.
  2. Migraine with aura: 25% of sufferers: aura includes visual disturbance(shimmering, stars, blurred vision) abnormal smells, localised numbness or tingling.
    About 6% of men and 15-18% of women are affected.

Trigger factors include:

Alternative diagnoses might include:

Treatment:

  1. start acute treatments of an attack as early as possible: pre-emptive measures such as aspirin, paracetamol, brufen, may stave off a full blown attack.
  2. Use of anti-emetic, to reduce sickness; a combination of aspirin 900mg and metoclopramide 10mg (as separate tablets) is effective in up to 50% of patients. Ondansetron has recently been found to be a safe and effective treatment of migraine-related nausea. Effervescent products have a more rapid effect.Opiates (which you might be taking for other types of pain) should not be used to treat migraines.(particularly as chronic use can actually lead to rebound headaches).
  3. A second line acute treatment might include sumatriptan: however, a recurrence of headache within 24 hours occurs in 30-40% of patients taking sumatriptan. Prophylaxis (prevention):

This is indicated if there are more than 2 attacks a month or of they are severe/prolonged. Usually, severity and frequency of attacks can be reduced, although there may still be need for acute treatment.

B-blockers such as propanolol are the treatment of choice; other options include pizotifen.

Note that drugs such as amitriptyline and gabapentin, which you may have had prescribed for treatment of nerve-related pain, have been found to be quite effective in reducing the frequency and severity of migraine attacks.

Naratriptan (related to sumatriptan) has been found to be effective prophylaxis against menstrually-associated migraine.

It is also interesting to note that use of high dose riboflavin (400mg) has been suggested as an effective prophylactic agent, but can take 2-3 months to take effect.

It should not be obtained from multivitamins as there is a risk of overdosing on other more toxic vitamins.

ATYPICAL FACIAL PAIN:

Note that dental problems are common in chronically ill people for a variety of reasons (this will be covered in a separate article).

However, often dentists cannot find a source for a patient's persistent facial pain.

The area around the mouth and the face (orofacial area) is highly innervated so extremely sensitive.

One of the commonest causes of non-dental facial pain is temporal tendinitis.

The temperomandibular joint (TMJ) is where the mandible (jaw) articulates on the temporal bone of the skull, hence the name of the joint. It is the joint which moves as you open and close your mouth or chew. It is a common site of problems.

TMJ problems cause the following symptoms:

TMJ pain (just in front of the ear): worse on chewing

Looking at the typical treatment of TGN:

The usual therapy is with an anticonvulsant such as carbamazepine or gabapentin. 
Occasionally, sodium valproate may be used.
Low starting doses and gradual increases are needed to avoid adverse effects.
If using carbamazepine, 100mg twice daily is the starting dose, increasing by
100mg each week until pain control is achieved.  Maximum dose is 1.6g daily;
usually 300-600mg is effective therapeutically. Once pain control has been
achieved, in cases where there has not been sustained pain (i.e. if there is an intermittent pattern of symptoms), the dose should be maintained for a month and then reduced by 100mg every 2 days. If the pain should recur, then the dose should be increased again. Doses should be taken 30 minutes before food and a double dose can be given at night to ensure adequate levels. Around 70% of patients have relief within 24 hours. (95% within 48 hours).

Liver function tests, blood count and blood biochemistry may be monitored (baseline before treatment, then every month for 3 months, then every 6 months)

Side effects include: dizziness, drowsiness. These are more common in the elderly.