Sunday, August 25, 2013

Peripheral Neuropathy

The term peripheral neuropathy is used to refer to many different types of neuropathy, from those involving only a single nerve, such as Bell’s palsy,
to those producing profound generalized paralysis, such as Guillain-Barre syndrome. There are also many different causes, ranging from heritary neuropathies to toxic ones caused by heavy metal poisoning.
A neuropathy is any abnormal state (pathy) of a nerve or nerves (neuro). The peripheral nerves are those that are outside the central nervous system, running from the brain or spinal cord to our muscles, organs, skin, etc. The peripheral nerves are usually divided into three types; motor nerves which go to muscles and control their contractions, sensory nerves which run from sensory organs to the spinal cord, and autonomic nerves which regulate many of our automatic functions such as controlling blood pressure, movement of the intestines, sweating, etc. A peripheral neuropathy may involve exclusively one type of nerve, or all three.
Some common conditions are actually neuropathies. I mentioned Bell’s palsy above; in addition there is carpal tunnel syndrome, which occurs when pressure at the wrist causes the nerves running through the wrist not to conduct correctly; trigeminal neuralgia, a painful neuropathy of the nerve going to the face; and shingles, an infection of the nerves by varicella-zoster virus. Some conditions are experienced by many people temporarily — for example, the numbness that can occur in the little finger and side of the hand during sleep when the elbow is bent to its maximum, which stretches the ulnar nerve in the elbow. But when most people, and most doctors, refer to peripheral neuropathy they are talking about numbness, tingling and pain, usually in the feet and legs.
Diabetes is a common cause of neuropathy, as is kidney failure. Maximum control of these underlying diseases may improve the neuropathy. There is an ancient disease, beri-beri, caused by thiamine deficiency, which causes such a neuropathy. No one eating a regular diet will develop beri-beri, and it is therefore seen in this country exclusively in alcoholics. For others, supplementing B complex vitamins will probably not help but won’t hurt, although megadoses should not be taken. (Megadoses of Vitamin B6, pyridoxine, have been shown to cause a neuropathy.)
Some cases of slowly developing neuropathies are hereditary, and usually inherited in a recessive fashion, meaning the parents and siblings will probably not have the disease. A careful family history that includes grandparents, aunts, uncles and cousins may give a clue.
Many drugs may cause a neuropathy, including some used in cancer chemotherapy, in the treatment of HIV infection, isoniazid used to treat tuberculosis, and others less commonly used. Severe alcoholism can cause a neuropathy that is not beri-beri and that will not respond to doses of thiamine. Infections that can cause it include HIV, Lyme disease, leprosy, polio, diptheria, and syphilis. Treatment of the underlying infection will often reduce the symptoms of neuropathy.

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Nasal spray made from ‘hot pepper’ eases shingles pain

A NASAL spray made from a compound found in hot peppers could be a new way to treat the severe pain associated with shingles.

  Now United States researchers have developed a spray to tackle this when it occurs in the face. The spray is designed to block pain signals in the trigeminal nerve, which is responsible for facial sensation.

  Shingles is caused by the reactivation of the chicken pox virus (the varicella-zoster virus). After causing chickenpox, the virus lies inactive in the nerves, where it is kept in check by a healthy immune system.

  But if this is weakened - because of advancing age, stress or disease - the virus ‘wakes up’. This can happen years, even decades, after the initial chickenpox infection.

  The virus then causes inflammation and damage to the nerves, triggering a rash and pain in the affected area - usually the chest or abdomen, though sometimes the face.

  A bout of shingles lasts two to four weeks, but up to one in five people will develop postherpetic neuralgia - severe chronic pain that persists for at least three months. In some cases, it can last ten years or more.

  The pain is variously described as a burning, stabbing, shooting, aching or throbbing sensation; the area can also feel itchy. It is not clear why some people develop pain after shingles.

  But the risk increases with age - postherpetic neuralgia affects one third of people aged over 80 at some time.

 Conventional treatments include low-dose anti-depressants and epilepsy drugs, which dampen down pain messages.

  The new spray, developed by U.S.-based Winston Laboratories, is based on capsaicin, the compound that makes chilli peppers hot. When eaten, capsaicin triggers a burning sensation by activating nerve cells - it’s thought that it tackles pain by desensitising the nerves.

  In a trial at the California Headache Centre, 40 patients with moderate to severe daily pain with postherpetic neuralgia will use the spray or placebo twice a day.

  The researchers say administering the drug, as a spray will be more effective than existing treatments at targeting the trigeminal nerve.

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Saturday, July 13, 2013

Trigeminal Neuralgia Diagnosis

Trigeminal neuralgia (TN) is defined by the International Headache Society (IHS) as “unilateral disorder characterized by brief electric shock-like pains, abrupt in onset and termination, and limited to the distribution of one or more divisions of the trigeminal nerve” [International Headache Society, 2004]. The IHS suggests a classification of TN as either classic (essential or idiopathic) TN (CTN) or symptomatic TN (STN; pain indistinguishable from that of CTN, but caused by a demonstrable structural lesion other than vascular compression). The diagnosis of CTN requires the absence of a clinically evident neurological deficit. CTN starts in the second or third divisions, affecting the cheek or the chin [International Headache Society, 2004]. The ophthalmic division alone is involved in less than 5% of cases [De Simone et al. 2005]. The single attack generally lasts from less than a second to a few seconds, but it may present in clusters of variable intensity with up to 2 minutes duration. In many cases it is followed by a brief refractory period during which a new stimulation is not able to evoke another attack. Between paroxysms the patient is usually pain free, but a dull background pain may persist in some cases [International Headache Society, 2004]. Growing neurosurgical data advocate the distinction of these two subtypes of TN into type 1 as defined as >50% episodic onset of TN pain and type 2 defined by >50% constant pain [Tatli et al. 2008; Limonadi et al. 2006]. The mechanisms associated with the development of this persistent pain are not well understood but concomitant background pain is associated with poor medical and surgical outcome [Obermann et al. 2008; Sandell and Eide, 2008; ]. Recent investigations focused on the suspected central component in the pathophysiology of TN, which could involve central allodynic mechanisms that may also engage the nociceptive neurons at thalamic and cortical level .

Microvascular Decompression

Microvascular decompression

Microvascular decompression is an operation to release the pressure of blood vessels pressing on the trigeminal nerve.

During microvascular decompression surgery, the surgeon will either remove or relocate the blood vessels, separating them from the trigeminal nerve.

For most people, this type of surgery is effective in easing the pain of trigeminal neuralgia and appears to provide the long lasting relief.

However, the operation can cause hearing loss which is estimated to occur in less than 3% of people. Also, it is possible for pain to return after surgery and for surgery to cause a loss of sensation in the face, but this is unusual and often temporary. Very rarely, this type of surgery can result in stroke, meningitis or even death.

Treating Trigeminal Neuralgia

Medication can provide temporary relief from the pain of trigeminal neuralgia. Surgery may be considered for people who experience severe pain despite medication, worsening pain or adverse effects from the medication.

Your Doctor will first prescribe a type of medicine called an anticonvulsant (usually used to treat seizures in epilepsy), which can help relieve pain in your face. These drugs work by slowing down electrical impulses in the nerve and reducing its ability to transmit pain. Normal painkillers such as paracetamol are not effective in treating trigeminal neuralgia.

The anticonvulsant medicine called carbamazepine (see below) is usually the first medication recommended. However, if carbamazepine is not effective, a different anticonvulsant called gabapentin may be used.


Although carbamazepine is usually used to treat epilepsy, it can sometimes be effective in treating trigeminal neuralgia because it lessens the uncontrollable pain signals.

You will usually need to take this medicine one to two times a day to begin with, although some people may need a higher dose.

Carbamazepine can cause side effects which may make it difficult for some people, such as the elderly, to use. Possible side effects are outlined below.

Very common side effects

These side effects have affected more than one in 10 people and include:

  • nausea (feeling sick) and vomiting
  • dizziness
  • tiredness
  • finding it difficult to control movements
  • a reduced number of infection-fighting white blood cells (leukopenia)
  • changes in liver enzyme levels (enzymes are proteins that speed up any reaction happening in the body)

Less common side effects

These side effects have affected up to one in 10 people and include:

  • increased risk of bruising or bleeding
  • fluid retention (being unable to pass urine)
  • weight gain
  • confusion
  • headache
  • blurred or double vision
  • dry mouth

Uncommon side effects

Uncommon side effects of carbamazepine can include:

  • uncontrollable (involuntary) movements such as tremors
  • abnormal eye movements
  • diarrhoea
  • constipation

Nice Guidelines for Neuropathic Pain