Trigeminal Neuralgia Treatment: Microvascular Decompression

Trigeminal neuralgia treatment starts with medication. When medication no longer controls the pain, the choice of Dr. Anil Kumar Kansal is microvascular decompression (MVD), an operation that separates the compressing blood vessel from the trigeminal nerve. He reports relief in about 90 to 95% of patients, a hospital stay of two to four days and a cost of around USD 6,000 to 7,000 at his centre.

Trigeminal neuralgia and Parkinson's disease are very different illnesses, but they bring patients to a neurosurgeon by the same route. Medication works first. Then it needs higher doses, causes side effects or stops working, and the patient's life narrows around the symptoms. Dr. Anil Kumar Kansal, Vice Chairman & HOD - Neuro Surgery & Neuro Spine, BLK-Max Super Speciality Hospital, New Delhi, India, has a clear position on both: for trigeminal neuralgia that medication no longer controls, microvascular decompression; for Parkinson's disease past the point of good drug control, deep brain stimulation. In each case, the quality of the result depends on choosing the right moment.

Trigeminal neuralgia symptoms: disabling but not dangerous

Trigeminal neuralgia causes attacks of facial pain along the branches of the trigeminal nerve, the main sensory nerve of the face. It is common and, in Dr. Kansal's words, very troublesome, although it is not life-threatening. The pain follows the nerve's three divisions: the first around the eyelid and forehead, the second below the eye, the third along the jaw. It can be strikingly localised. One of his recent patients had pain only on one side of the tongue, and was relieved by surgery.

The disability comes from the triggers. Patients cannot shave, brush their teeth, drink or eat without provoking an attack, and sometimes cold or a breath of air is enough. One of his patients reached the point where the pain stopped him eating or feeding himself.

Why medication for trigeminal neuralgia eventually falls short

Medication is enough for some patients, but others need doses high enough to cause side effects, and for some the pain continues regardless. Dr. Kansal describes patients taking three or four medicines who still have pain on around ten days a month, enough to disrupt their work and their lives.

Trigeminal neuralgia causes and MRI diagnosis

In the majority of patients the cause is a vascular loop, an artery or sometimes a vein, compressing the trigeminal nerve and damaging its insulating myelin at the point of contact. Less often, the cause is a demyelinating disease such as multiple sclerosis, or a tumour pressing on the nerve.

Diagnosis rests on two steps:

1. The clinical picture. The diagnosis is clinical first.
2. Good-quality MRI with dedicated sequences. Standard MRI is not enough. Dr. Kansal relies on 3D CISS sequences, a high-resolution MRI technique that shows nerves and vessels in fine detail, with multiplanar reconstruction, together with MR angiography. These show whether a tumour is present and, where a vascular loop is responsible, exactly where it is compressing the nerve. In one of the scans he presented, the compression was visible on both sides.

Trigeminal neuralgia surgery options compared

When medication fails, four procedures are available, and Dr. Kansal has used all of them:

• Glycerol injection. Early in his career, at a leading neurosurgical hospital in Delhi, he gave hundreds of glycerol injections. Patients came back six months to a year later with the pain returned, and some are left with numbness of the face.
• Radiofrequency ablation. As with glycerol, some patients are left with numbness of the face.
• Gamma Knife radiosurgery. It takes weeks to months to work, and its relief is less complete and less durable than that of microvascular decompression. Patients are pleased at first to have avoided an operation, but the pain returns more often.
• Microvascular decompression. For the last several years his team has performed only this operation, keeping injections and radiofrequency ablation for patients who cannot undergo surgery.

How microvascular decompression is done

Microvascular decompression is performed through a small craniotomy, an opening in the skull, behind the ear. The cerebellum is gently retracted to expose the nerves at the base of the brain. In the case Dr. Kansal showed, the anterior inferior cerebellar artery came into view and was moved aside, revealing the glistening fifth nerve with a vascular loop touching it. That loop is the culprit. The vessel is separated from the nerve and a small patch, usually Teflon, is placed between them. An intraoperative photograph showed the indentation the vessel had left on the nerve.

Microvascular decompression success rate, recovery and complications

Dr. Kansal reports that 90 to 95% of patients are relieved of pain after microvascular decompression, with serious complications under 1%. In his lecture he described about 90% of patients being relieved, with relapse uncommon, making it the most durable of the surgical options. Asked later about outcomes, he put the figure at 95% of patients pain-free after surgery. Recurrence was raised in the masterclass Live Discussion; early recurrence is about 5% in his experience. Across more than 100 of these operations his team has not had to operate a second time, although some patients have mild symptoms that settle with medication or reassurance.

Recovery is short:

• the patient walks from the day after surgery;
• the hospital stay is two to four days;
• a post-operative CT scan checks for bleeding or any collection;
• medication is continued for one month and then stopped.

The possible complications are the risks of anaesthesia, and on the surgical side a haematoma in the cerebellum, bleeding, infection and nerve injury. His infection rate is very low. One patient developed chemical meningitis followed by hydrocephalus and needed a shunt. In the early years a few patients reported partial hearing loss from traction on the eighth nerve, the hearing nerve, which runs close to the fifth. His team now uses very minimal traction, and complications have become rare.

When not to operate on trigeminal neuralgia

Surgery is not the answer for everyone. If a patient's pain is controlled on minimal doses of medication, Dr. Kansal does not operate unless the patient wants it. Surgery is for patients whose pain is not relieved.

Microvascular decompression cost versus long-term medication

At his centre, microvascular decompression costs around USD 6,000 to 7,000. He estimates that within about six months, the cost of medication matches the cost of the operation. Since the operation has few complications and a durable result, it is in his view the financially better choice over the long term as well as the clinically better one. Quotations from Indian hospitals are summarised under other brain and neurosurgery procedures cost.

Deep brain stimulation for Parkinson's disease: when to operate

Deep brain stimulation is best timed for the point at which Parkinson's medication stops giving steady control, usually after a honeymoon of about four to five years on drugs.

The honeymoon and what follows

Parkinson's disease results from a lack of dopamine production in the brain. Patients have difficulty walking, tremor, rigidity, a mask-like face and a general slowing of movement. Treatment starts with levodopa, a drug the brain converts into dopamine, at a low dose that is increased gradually.

The drugs usually work very well for a few years, a honeymoon period of about four to five years. After that, one of two things happens. Either the dose has to rise so high that drug side effects appear, or the effect of each dose fades and the symptoms return within a short time of taking it. By three or four years into treatment, a patient may be taking medication four or five times a day and still not be comfortable.

Deep brain stimulation as a planned next step

That point is, in Dr. Kansal's view, the ideal time to operate. He does not present surgery as an alternative to medicine. In the early years the neurologist leads, because when drugs are working well no surgery is needed. Once the patient stops responding, side effects appear or life becomes seriously compromised, deep brain stimulation has a role, and the neurologist and neurosurgeon need to agree on it together. Combined medical and surgical treatment, with the right timing and indication, is what produces good results.

The procedure

Deep brain stimulation places electrodes in the subthalamic nucleus, a small structure deep in the brain involved in controlling movement:

1. A stereotactic frame is applied to the head to define the target.
2. The patient is kept awake while the electrode is introduced.
3. The team stimulates through the electrode and asks the patient to move the hands and legs, checking that the electrode is in the right place and how much current is needed.
4. Once the right site is confirmed, the electrode is fixed and connected through leads to a pulse generator, a pacemaker-like device placed in the chest wall.

After surgery the patient improves clinically, the drug dose can be reduced, and daily life becomes better.

Deep brain stimulation cost and results beyond Parkinson's disease

Deep brain stimulation is costly, around USD 30,000 to 40,000 at his centre. Dr. Kansal notes that complication rates have fallen and describes the results as excellent. The technique is not limited to Parkinson's disease: his team recently treated a patient with dystonia, a disorder of involuntary muscle contraction, who could not stand properly and had abnormal movement on one side of the body, and the patient did very well.

Focused ultrasound: a lesion without an incision

Focused ultrasound is a newer technique that is still developing. It creates a lesion deep in the brain without an incision; it is approved for essential tremor and for tremor and dyskinesia in Parkinson's disease, and its use in conditions such as dystonia and refractory pain is still being explored. Dr. Kansal's caution is that it is a destructive procedure: once the lesion is made, it cannot be reversed. Deep brain stimulation, by contrast, can be adjusted after implantation.

For the principles of patient selection, timing and cost across the whole field, see the complete guide to recent advances in neurosurgery. The stereotactic and navigation tools that also underpin electrode placement are covered in brain tumour surgery techniques, from navigation to Gamma Knife.