Trigeminal neuralgia: etiology, symptoms and treatment

Trigeminal neuralgia or tic douloureux is one of the diseases known since ancient times. The general picture of facial pain episode appeared only at the end of the XVIII century, when British medical specialists due to the development of civilization became able to arrange all the data, collected in the written sources since the ancient times. At that time they already knew all about the initiating agent, but almost nothing about the nervous system function or impulse transmission – these were empirical knowledge.

Nevertheless, treatment of trigeminal neuralgia with opium medications was successful, but at the same time a lot of patients became addicted to the drug because of its strong side effects. The case is that the pain in trigeminal neuralgia was extremely severe. Not only the episode itself, but even a memory or  waiting can be stressful enough for some persons to commit a suicide. In non treated or improperly treated patients’ suicidal attempts happened not only during the pain episode, but as well while expecting it.

Trigeminal neuralgia is a functional disorder of the peripheral nervous system, which is instantiated by intermittent pain in one side of the face.

Etiology

The most common reason is a compression of the nerve or its ganglion (peripheral node) by the external object in the cranial cavity.

It can be (the most frequent case) pathologically tortuous artery – arteria cerebellaris superior – upper cerebellar artery. Near the junction of the spinal cord trigeminal nerve  passes at close quarters with the blood vessels. Nerve compression usually develops in patients with congenital defects of the vessel walls in case of arterial aneurysm, especially when the systemic blood pressure is significantly increased. If the trigeminal neuralgia onset happens during the pregnancy, the mechanism is probably the same. Such pain usually goes away simultaneously after the delivery.

Medullary sheath defect

So-termed demyelinating diseases, such as Davic’s disease, disseminated sclerosis, acute disseminated encephalomyelitis can cause neurological pain. In this case it is qualified as a symptom of a more complicated disease and is called secondary trigeminal neuralgia.

Nerve trunk compression by the tumor mass

The causative neoplasm can be benign or malignant, arising either from nervous tissue or meninx. Neurofibromatosis is a classic example, multiple fibromas growing in different parts of the body can show various symptoms, neurological pain, trigeminal or with other localization  is one of them

Post traumatic neuralgia

Severe concussion or brain contusion, long continued unconsciousness can cause the formation of intracerebral cyst. While growing it compresses soft tissues and the nerve trunk which causes pain.

Post herpetic neuralgia is a very unpleasant condition accompanied by the neurological pain, but fortunately it happens quite rarely.  In this case bullous rash similar to that in a chickenpox appears on the face skin in projection of the big nerve trunks, after that comes severe burning pain. These symptoms indicate to the neuropathological pain as a result of nervous tissue damage by the herpes virus.

What can cause a pain episode?

Every pain episode in patients with neuralgia is a result of the trigeminal nerve irritation due to trigger area or a dolorogenic zone induction. They are usually localized on the face skin in nose or eye corners or a nasolabial fold. Being irritate even with minimal effort, the trigger points can generate a long lasting, stable pain impulse. The most common dolorogenic factors are:

  • Shaving of the face in men. Looking at a patient with a big shaggy beard, the fist thing an experienced neuro specialist thinks so is trigeminal neuralgia;
  • Just a light face stroke. Patients with trigeminal neuralgia do their best to keep the face out of any disturbance. They don’t use a handkerchief or a paper nose-wipe;
  • Eating or tooth brushing. Active movements of the face and oral muscles, pharynx constrictors can cause pain due to associated face skin movements;
  • Drinking water or other fluids. That is another reason why trigeminal neuralgia is considered to be a very cruel disease. Even a simple process of thirst satisfying can be extremely painful for these patients;
  • Smiling, crying or laughing as well as talking;
  • Doing the make-up;
  • Aggressive odours such as acetone or ammonia spirit can also cause pain, that’s why sometimes they are called trigeminal.

As you can see, every movement of the facial muscles  or the skin can cause an episode in patients with trigeminal neuralgia. At least the temperature drop when coming from warm room outside as well as a slight wind can promote severe pain. That’s why patients with trigeminal neuralgia consider their own face a train wreck waiting to happen.

Clinical aspects

Neurological pain is described as a lighting or a stroke of electricity, sometimes it is quite intensive to cause loss of consciousness. Typical localization ode side of the face: cheeks, lips, teeth, forehead and orbital. By the way frontal branches of the trigeminal nerve are rarely affected by neuralgia.

Neurological pain has no irradiation, it is localized only in the face skin and does not spread to the arm, tongue or an ear. More than that only one side of the face is affected during the one episode. It never happens that the two sides of the face hurt at the same time.

The pain episode usually is very short, it lasts only several seconds. The frequency of the neurological attacks as well as lucid space interval duration is quite variable. Usually the pain free period lasts from several days to weeks.

Neurological pain can be so strong that it makes the patient to freeze, cause pupil dilatation or tearing.

Diagnostics

The clinical signs of the trigeminal neuralgia are so typical that it is not difficult to put the diagnosis at all. But it is really hard to distinguish the primary source of the problem, that is the main task for a neuro specialist. One can diagnose true primary trigeminal neuralgia only after the oncological or an expansive process or any other reason for the nerve compression is excluded.

That’s why MRI or computer assisted contrast vasography can be very helpful. The CT scan must have high resolution with the magnetic field intensity of more than 1.5 tesla.

Treatment

There are two treatment strategies: conservative management and surgery.

Traditionally, trigeminal neuralgia is first treated with medication and only if conservative management is totally ineffective, an opportunity of the surgical treatment is discussed.

Medical drugs, used to treat trigeminal neuralgia:

Seizure medications (anticonvulsants) are prescribed for patients with trigeminal neuralgia because they are able to eliminate congestive excitation focus in neurons, which is similar to the seizure focus in the cortex in patients with epilepsy. The treatment begins with 200 mg of carbamazepine per day, than the dose is consequently elevated to 1200 mg per day;

Central muscle relaxants such as tolperisone or tinazidine act upon the neurons, responsible for the muscle tonus. They help to reduce muscle tightness and spasm, and as a result, to reduce the trigger point sensitivity and the frequency of the pain episodes;

Simple analgesics are not effective in reducing severe burning pain in postherpetic trigeminal neuralgia. In this case medical drugs for neuropatological pain treatment such as pregabaline or gabapentin are prescribed.

If conservative management is totally ineffective, quality of life is significantly decreased and the duration of the lucid intervals falls – surgical treatment is discussed.

There are two surgical methods of treatment, ordered by level of difficulty:

  • nerve block of the whole trigeminal nerve or its branches: ophthalmic, maxillary or mandibular nerve. This method is used in elderly patients with hard comorbidity and on condition that only one branch of the trigeminal nerve is affected. The nerve block is carried out with novocaine or ethanol. The therapeutic benefit is usually present for a year or so.
  • The trigeminal nerve ganglion block is more complicated surgical intervention. To reach the Gasser’s ganglion, one must get an access to the temporal bone basis in the skull cavity. Now it can be done by an atraumatic puncturing, such as during the glycerol percutaneous rhizotomy. In this case sterile medically clear glycerol is introduced into the ganglion, and after several hours, the nerve is devitalizes.

Pathological neuron groups can be destroyed by chemical, thermal or radio-frequency agent.

  • Unilateral trigeminal nerve root trans-section is a quite traumatic, but radical operation. To perform it the neurosurgeon has to drill several holes in the skull and make a encephalotomy. This operation is not performed now because of high risk of complications and low effectiveness.
  • The cross-section of nerve tracts leading to the sensitive trigeminal ganglion is another high-technology medical manipulation. It is effective if the pain is localized in Solder’s zones or correspond to the ganglion areas.
  • Decompression of the Gasser’s ganglion is carried out if it was proven that the nerve is compressed by a blood vessel. In this case the neurosurgeon disconnects the blood vessel from the trigeminal nerve ganglion. Then the blood vessel is covered by the muscle flap or a special artificial material.

This operation is not radical, but it helps to reduce pain for a definite period of time and has one undeniable advantage: all the nerve structures are preserved, so the face skin sensitivity is not compromised.

Radical operations have one very unpleasant side effect a full loss of sensitivity on the affected side of the face. It feels a bit like stomatological anesthesia, but lasts for a lifetime.

Full numbness of the face is a very uncomfortable condition, one can bite his cheek, for example, and would feel nothing. But what is more  dangerous, dental disorders on the affected side. A tooth can be badly destructed with no toothache at all. That’s why patients with postoperative anesthesia should see their dentist regularly.

And at least there is one innovative atraumatic and noninvasive method of treatment of trigeminal neuralgia. It is gamma-knife or a charge particle accelerator.

This treatment is very expensive for the patient, but still it is cost-effective. During the procedure the affected part of the brain is worked up by several charge particle beams from the sources, located inside the special frame of the apparatus.

As a stream of light, focused by several mirrors like surfaces can burn the fire, the resulting charge particle beam from the cobalt-60 destroys the abnormal brain focus with a high precision of about 0.5 mm. The procedure is so atraumatic, that the patient can leave the hospital just at the day of treatment by his own feet.

Prophylaxis

Trigeminal neuralgia is too hard to prevent. There are a lot of internal factors, not depending on the person’s behavior, so it is very difficult to tell what to do or what not to do to prevent neuralgia. The patients with tic doloreux usually know what can trigger the pain attack and try to avoid it.

The only advice we can give is to visit the neurospecialist as soon as possible if you’ve had a neurological pain attack. It is very important to have an executive check-up, because in case of secondary symptomatic neurological pain it is important to begin  treatment as early as it is possible.

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