Saturday, June 9, 2012
Recently after the famous Bollywood star (Salman Khan) was referred for surgery for trigeminal neuralgia, there is a lot of interest in this condition.
What is trigeminal neuralgia?
Trigeminal neuralgia (TN), also referred to as suicide disease, is a condition characterized by intermittent severe, sharp, shooting pain usually affecting one side of the face (the area over face, which is supplied by the fifth cranial nerve, also called the trigeminal nerve). Facial sensations such as hot or cold temperature, touch and pain are transmitted from face to the brain, via the trigeminal nerve. The nerve is called trigeminal nerve, as it has three branches supplying sensations over the upper, middle and lower thirds of the face, respectively.
How common is trigeminal neuralgia and who are affected by it?
TN is an uncommon condition, affecting 155 per million population. Male to female ratio is 2:3 (it is more common in females). TN mostly occurs after age 50, but it may affect people in 25-50 age group also. In younger patients, multiple sclerosis is a common cause of TN. Children are usually not affected by TN.
What are the clinical features of TN?
· Patients suffering from TN usually complain of severe, sharp, shooting pain affecting one side of face. Pain is usually located in the middle and lower thirds of the face, and the upper one third is uncommonly affected.
· Pain may also occur in the lips, gums, teeth, eye, ear, forehead or cheeks.
· It is described as a lancinating pain or as an electric-shock like sensation.
· Pain often affects only one side of face, however, in some cases (about 10% of those affected); pain may involve both sides of face.
· Pain is of short duration, often lasting for a few seconds and rarely lasting for more than 1-2 minutes.
· Pain recurs several times in a week and sometimes several times in a day.
· Patients are often normal in between the pain attacks.
· There may be relative periods of improvement lasting for a few months.
· Facial pain gets aggravated by simple activities like brushing teeth, washing face, chewing food, shaving and sometimes by light breeze/air from fan or AC.
· Trigeminal neuralgia, if left untreated, may become chronic and persist for several years.
· Pain in TN is often severe and repetitive, thereby, hampering the activities of daily living. Many patients have problems performing their daily jobs due to the pain.
How do we make a diagnosis of TN?
· The diagnosis of TN is made on the basis of clinical description of facial pain (as described above). Detailed neurological examination by a neurologist is helpful in excluding a secondary cause. In cases of TN, clinical examination findings are normal (except for mild numbness over face in some cases).
· TN gets misdiagnosed in some cases. Pain may seem to arise from the teeth region, as the trigeminal nerve supplies that region also. So, patients often visit a dental surgeon in the initial period. However, even after removal of teeth and dental treatment, the pain persists. I have had patients who were referred to me, only after several teeth were extracted. Occasionally, patient may visit an ENT surgeon as sometimes the pain seems to arise from behind the ear.
· Generally, no investigations are required to make a diagnosis of TN. However, an MRI along with MR angiogram of the brain is required to exclude any secondary cause of TN.
What are the causes of TN?
Very often, no cause can be identified (these cases are called idiopathic). However, in many patients, there could be secondary causes which can be easily identified on the brain MRI scan. These may include:
· Compression over the trigeminal nerve by a neighboring blood vessel,
· Multiple sclerosis (a condition affecting brain and spinal cord, where the nerve covering-myelin sheath- is damaged)
· Cystic mass lesions (which contain fluid)
· Benign tumors (non-cancerous tumors)
· Infections in the region of trigeminal nerve (bacterial or tuberculous).
· Idiopathic- there are several patients suffering from TN, where no specific cause can be found out.
How do we treat trigeminal neuralgia?
TN is usually treated with medications (simple analgesics or medicines to relieve the neuropathic pain). These may include carbamazepine, oxcarbazepine, gabapentin, pregabalin, amitryptiline, etc. Drugs are started at a low dose, and the dose is titrated upwards depending on the treatment response and the occurrence of any side effects. More than half the patients do well with medical treatment alone. However, some patients do not respond to medical treatment or have significant adverse/side effects (such as drowsiness, dizziness, imbalance, skin rashes, etc). These patients can be treated by radio-frequency ablation or microvascular decompression.
Non-medical treatment of trigeminal neuralgia
1. Radio-frequency ablation of a portion of trigeminal ganglion (laser treatment). This procedure is carried out by radiation therapist in consultation with neurosurgeon.
2. Anesthetic blocks (injections of anesthetic drugs) of the trigeminal ganglion. This procedure is carried out by anesthetists.
3. Gamma knife radiosurgery (it is a radiation treatment and not a surgery).
4. Microvascular decompression- it is a surgical procedure where the trigeminal nerve is freed/released from any compression by a vessel or other surrounding tissues. This procedure is carried out by the neurosurgeon.
What is the outcome of TN?
TN responds well to treatment and most of my patients do well with medical treatment. I refer some patients for radiofrequency ablation or surgery. Most patients are pain-free after treatment. TN does not lead to death or paralysis or any physical disability.
(Footnote: At the time of writing this piece, Salman Khan has undergone a successful surgery, and is recovering well).
(This article was first published in March 2012 issue of health magazine Complete wellbeing)
DR SUDHIR KUMAR MD (INTERNAL MEDICINE), DM (NEUROLOGY)