Trigeminal Neuralgia

The disorder is characterized by episodes of intense facial pain that last from a few seconds to several minutes or hours. Patients can pinpoint their pain accurately. The pain is not restricted to any division of the trigeminal nerve but generally runs along the line dividing either the mandibular and maxillary nerves or the mandibular and ophthalmic divisions of the nerve. Ophthalmic branch involvement is seen in less than 5% of patients [12].

The pain comes in paroxysms. The patient may describe the sensation of pain, in a particular trigger area on the face which is so sensitive that touching or even air currents can cause the pain. In some patients, the pain may start without any stimulation also. Generally, these trigger zones are seen near the nose or mouth [13]. Common day to day activities like eating, smiling, shaving, talking, brushing teeth can also trigger pain. Often a loud noise, wind, high pitched sounds can also worsen the condition in few cases.

Patients define pain as if they feel like stabbing, burning, pressing, electric shock like, crushing or shooting pain that cannot be traced. At the time of attack, patients may wince, grimace or make a nasty head movement so as to get away from pain, thereby generating an apparent movement or tic and hence the term tic douloureux.

The number of attacks can differ from less than 1 per day to around 12 or more per hour and sometimes even up to hundreds per day. In the beginning, lot of patients develop pain in one branch and after a couple of years the pain travels to other branches. Few patients complain of pain in index finger along with too [14].

It is generally diagnosed on the basis of the patients history of pain, the triggering factors for the pain and the type of pain. No laboratory or radiologic testing is indicated on routine basis to diagnose trigeminal neuralgia. Imaging studies like CT scan or MRI are indicated to rule out tumors or multiple sclerosis. MRI is done in patients younger than 60 years of age presenting with the pain to rule out tumors and it can also reveal multiple sclerosis plaque and pontine gliomas if present [15].

Magnetic resonance angiography (MRA) is used to locate vascular compression if any, but it is not very sensitive. It should be differentiated from temporomandibular disorder [16] as pain can be triggered by movements of tongue and facial muscles.

Treatment includes both pharmacological as well as surgical approaches.

Pharmacological approach includes the following:

• Anticonvulsants: First line of treatment includes carbamazepine followed by second line medicines like oxcarbazepine, sodium valproate, gabapentin, pregabalin, phenytoin and. In some cases, clonazepam and lidocaine have also been effective [17].
• Anti-spasmodics: Muscle-relaxing agents such as baclofen can be used alone or in combination with carbamazepine.
• Antidepressant: Duloxetine is used in few cases of neuropathic pain when present along with depression [18].
• Opiates: Morphine and oxycodone along with gabapentin is effective in cases of neuropathic pain. Gallium maltolate in a cream or ointment base has been found to relieve refractory postherpetic trigeminal neuralgia [19].

Surgical approach

It is recommended when the medical line of treatment does not provide the necessary pain relief [20].

Microvascular decompression is a procedure involving relocation or removal of blood vessels that are in contact with the trigeminal root. This procedure gives the longest period of pain relief [21].
Percutaneous radiofrequency thermorhizotomy can also be useful [22].

Likewise, gamma knife radiosurgery is also useful but its effectiveness reduces as with passage of time [23].
Balloon compression is a cost-effective percutaneous surgical procedure, which is helpful in treating aged patients that cannot undergo surgery due to other health issues. It is the best option for those who have ophthalmic nerve involvement or have complains of persistent pain after microvascular decompression.

Glycerol injections involve injecting a small amount of sterile glycerol, which damages the trigeminal nerve and blocks pain signals.

Radiofrequency rhizotomy is a procedure wherein the surgeon uses an electrode to heat the selected division or divisions of the nerve. If done properly this procedure can target the exact regions of the erratic pain triggers and disable them with minimal numbness.

Trigeminal neuralgia is not a life-threatening disease, but its effects last for a long time and can be disabling. Many people have periods of remission with no pain for months or years. There is unscientific evidence that it worsens as time goes by and becomes less responsive to treatment [11].

Most cases of trigeminal neuralgia are primary or idiopathic, but the compression of trigeminal roots can cause pain due to tumours or vascular anomalies. Compressing vessels can be superior cerebellar artery or venous compressions that cause the pain [2].

Aneurysms, tumors, chronic meningeal inflammation, or other lesions may irritate trigeminal nerve roots along the pons causing symptomatic trigeminal neuralgia.

Tumor-related causes of trigeminal neuralgia commonly seen in the cerebello-pontine angle are acoustic neurinoma, arachnoid cyst [3] glioblastoma, [4] epidermoid, metastases, and lymphoma.

Vascular causes could be pontine infarctions or arteriovenous malformation or an aneurysm in the vicinity.

Inflammatory causes enlist multiple sclerosis [5], sarcoidosis, and Lyme disease neuropathy.

Adjacent dental fillings made up of different metals may trigger attacks [6]. Various triggering factors such as eating, drinking, talking, brushing teeth, shaving, smiling, coming in contact with breeze etc, can lead to this pain.

In 1956, US prevalence of TN was around 107 men and 200 women per million people [7]. Recent studies suggest the prevalence of around 1.5 cases per 10,000 people. It has been reported that around 1% of the patients having multiple sclerosis develop TN [8] and it was also seen that 2% of the patients with TN have multiple sclerosis [9].

Females are more prone to it, almost two times as compared to males. In most of the cases, the disease starts after the age of 40 years.

Trigeminal nerve is a sensory nerve and hence can produce pain. In most of the cases, no structural lesions are detected but researchers agree to the presence of venous or arterial loops at the entry of trigeminal nerve into the pons that lead to compression of the nerve and thereby to pain. This compression leads to focal demyelination of the trigeminal nerve.

Neuropathic pain is the fundamental sign of injury to minute unmyelinated and scarcely myelinated primary afferent fibers that work in processing noxious stimuli. The pain mechanisms are transformed. The damaged nerve fibres cause emphatic transmission, wherein the action potentials jump from one fibre to another [10]. Absence of inhibitory inputs from big myelinated nerve fibers plays an important role. In addition, the re-entry mechanism leads to amplification of sensory inputs.

Trigeminal neuralgia cannot be prevented, but once the patient has it, there are steps to avoid the attacks of pain by taking following measures:

• Eating soft foodstuffs.
• Eating and drinking foodstuffs that are at room temperature.
• If brushing teeth triggers attacks, clean the mouth by rinsing it with warm water after meals.
• Avoid known triggers like heat, cold, touch, loud noises etc.

Trigeminal neuralgia (TN), also known as Fothergill’s diseases [1] or tic douloureux, is a neuropathic disorder manifested by episodes of intense pain in the face rising from the trigeminal nerve. It has been described as one of the most painful conditions known to mankind so much so that it can drive the patient to commit suicide.

Trigeminal neuralgia is one of the most painful neuropathic diseases known to mankind. The pain is so much so that, it depresses the patients and gives them thoughts of committing suicide. The pain hampers the persons day to day activities like talking, chewing, washing face, smiling etc.

Physically, the patient seems to be fit but mentally the patient is frustrated due to the pain and the fear of triggering the pain. The exact cause of this condition is not known but various theories of blood vessels compressing the nerve or presence of tumors or demyelinating diseases leading to the condition have been put forth.

The treatment includes various drugs that can relieve the pain and some surgeries that may be effective if the medical line of treatment fails. Apart from medicines, patient should take care of avoiding the triggering factors like cold, heat, touch etc. to prevent the attack of pain. Alternative medicines like nutritional therapy, acupuncture, vitamin therapy etc. can be given a shot, as they might be useful in some cases.

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