What is Postherpetic Neuralgia?

December 29, 2019

Herpes zoster is a virus that causes chicken pox in childhood.  In adult life, if it recurs, it causes “shingles”, an outbreak of small lesions on the skin.  They usually occur in the distribution of a nerve root.  If the nerve root is the trigeminal nerve, the outbreak will occur on the face, usually in V1, the forehead and eye.  The outbreak is painful.  If you have this you should seek immediate medical attention, since early drug treatment can prevent chronic pain.

About 10% of people with a zoster infection develop chronic pain in that distribution.  It’s called “postherpetic neuralgia.”  The best medical treatments involve topical application of capsaicin cream.  It burns, a lot.  But if you use it for 2-3 weeks the postherpetic pain often diminishes.

If your pain is totally incapacitating, you may be a candidate for an operation called the “nucleus caudalis dorsal root entry zone lesion (DREZL) procedure.  This involves surgery, under general anesthesia, where a needle is placed into the pain center of the brainstem and lesions are made.  At UF, we have performed many of these procedures.

Radiosurgery – Is it the right choice?

March 26, 2019

Radiosurgery is an outpatient treatment that focuses hundreds of very small beams of radiation on an intracranial lesion.  It has revolutionized the treatment of small brain tumors (including metastatic tumors, meningiomas, schwannomas, and others) as well as brain blood vessel malformations.  It has also been used for some time to treat trigeminal neuralgia.

If you are considering radio surgery, make sure that you are dealing with a very experienced radiosurgery team.  The trigeminal nerve target is very small, so absolute accuracy is required and this is not available on every commercial radiosurgery system.  I would recommend systems that use a head ring and have a proven mechanical accuracy of less than .5mm.

I have used radiosurgery to treat over 4500 patients since we first started in 1988.  We have extensively published our results (over 150 papers and chapters) and spoken at over a 100 international and national meetings.  I was president of the International Stereotactic Radiosurgery Society.  And yet I am not very enthusiastic about radiosurgery for trigeminal neuralgia.  Why?

  1.  It takes 6-8 weeks for radiosurgery to produce pain relief.  Many of my patients can’t wait that long.
  2. Many patients still need to take medication after radiosurgery to control their pain. Why is that a problem.  Well, side effects of medical treatment are what bring most patients to surgical treatment.  If you have to continue meds, disabling side effects may also continue.
  3. Radiosurgery has a poorer long term pain control record than microvascular decompression.  That is, your pain relief is more likely to be temporary than with other surgical approaches.

That said, the advantage of radiosurgery is that it virtually eliminates the rare but occasionally very serious risks of open surgery.  If radiosurgery fails, it will not preclude you from pursuing other options.

So, think about it!

Multiple Sclerosis and Trigeminal Neuralgia

March 12, 2019

Multiple sclerosis (MS) is a “so-called” demyelinating disease.  Myelin is the substance which surrounds nerve fibers and enables them to conduct fast electrical impulses.  In MS, the body’s immune system attacks the myelin leading to spots (called plaques) that are bare of myelin.  This leads to a variety of neurological symptoms, including loss of vision, loss of sensations, and loss of motor function, amongst others.  Sometimes these symptoms are temporary and sometimes permanent.  The treatment of MS is medical.  In the past five years a number of new drugs have been approved for treatment.

Trigeminal neuralgia may also occur, as a result of demyelination, in MS patients.  The symptoms are identical to TN in patients without MS.  But, again, the cause is different. Usually, in “regular” TN, we find an artery or a vein compressing the trigeminal nerve.  Moving that vessel usually relieves the pain, hence the “microvascular decompression procedure.”  In MS, microvascular decompression is much less likely to work because its a plaque in the brainstem, not a vessel, which is causing the pain.  Another unusual thing about MS trigeminal neuralgia is that it is frequently bilateral.

The treatment of choice for MS patients with trigeminal neuralgia is, therefore, the radio frequency lesion procedure (RFL).  This outpatient procedure takes about 10 minutes.  During brief anesthesia, a needle is inserted into the trigeminal nerve and the nerve cells are burned.  This leads to numbness in the region where the pain was previously present, but the pain is gone.  The procedure can be performed on both sides of the face, but care must be taken not to create bilateral jaw weakness or tongue numbness.

What’s the best medication for trigeminal neuralgia?

February 27, 2019

Almost all patients with trigeminal neuralgia are first treated with medication.  The medication of choice is carbamazepine (Tegretol).  Very commonly, patients are started on a dose that is too high and that can produce significant side effects, like drowsiness, mental slowness, and imbalance.  The key is to start at a low dose.  I usually recommend 100mg twice a day.  That dose will usually lead to rapid relief (within 24 hours) of trigeminal neuralgia, with minimal or no side effects.  Over time, many patients have to gradually increase the dose to provide pain relief.  As long as this is done slowly, side effects will be rare.  Tegretol blood levels are NOT a useful guide when using the drug for facial pain.  Routine blood tests are NOT necessary unless you start to feel unwell.  In such cases, your doctor will check your blood chemistry, blood counts, and liver function as they can, rarely, be affected by this drug.  Tegretol has been used for decades in large numbers of patients with epilepsy, as well as facial pain.  It is safer than surgery.  Surgery is reserved for those cases where medication fails to control pain or causes intolerable side effects.