Surgery for Chronic Pain: Trigeminal neuralgia
Introduction
Trigeminal neuralgia (V cranial nerve) is a type of pathology characterised by episodes of intense pain in the eyes, ears, nose, forehead, cheeks, mouth, jaw and side of the face. The pain is so intense that in the past when there was no treatment it was even called suicide disease.
Signs and symptoms
The main symptom is episodes of intense, sudden onset shooting pain. Sometimes the pain crisis is triggered by an outside factor: chewing, eating something cold, touching the face, etc.
It is a very intense unilateral shooting pain, without any forewarning and mainly affects the second and third branches of the trigeminal nerve. Outbreaks lasting 1 or 2 minutes, often variable.
Diagnosis
The main diagnosis is clinical but it is essential to perform imaging tests (magnetic resonance imaging) to reject any cause that is irritating the nerve.
There are two forms of Trigeminal neuralgia: Primary or secondary. Primary forms are the most frequent. There is no cause (illness) to explain the pain, nevertheless in the majority of cases the underlying cause (even though not visible on cerebral resonance) is vascular compression of the trigeminal nerve at the point where it leaves the brain stem. Secondary forms may be: Brain tumours in the cerebellopontine angle, patients with multiple sclerosis.
In the event of secondary forms, the cause must be treated first, and in cases of multiple sclerosis it is possible to offer some of the treatments available for primary forms of trigeminal neuralgia.
Treatment
The drugs used to improve trigeminal neuralgia usually have considerable side effects and this must be considered when deciding to opt or not for a surgical alternative.
Treatment varies depending on the type of neuralgia and the results of complementary tests. In general there are three treatments:
- Pharmacological treatment where carbamazepine is the most frequently prescribed medication.
- Percutaneous techniques: an injection that attempts to anaesthetise the nerve so that it ceases to cause pain.
The most common solutions are the Mullan technique (using a Fogarty balloon to compress Gasser’s Ganglion) and radiofrequency applied to Gasser’s ganglion. Both techniques are simple and with a low complication rate. In the case of the Mullan Technique, a general anaesthetic is used, whereas applying radiofrequency to Gasser’s ganglion only requires sedation and local anaesthesia. The probability of success is the same for both techniques. The probability of improvement is 75%
- 3. The Jannetta Technique (microvascular decompression surgery) is cranial surgery, with craniotomy and under a general anaesthetic. In a large percentage of cases the cause of the neuralgia is vascular compression. Decompression resolves or minimises the pain caused by irritation of the nerve. The success rate is 95%. There may be complications. The surgery consists of separating the vessel (generally an artery) that presses on and irritates the trigeminal nerve. Decompression resolves or minimises the pain caused by irritation of the nerve.
