Trigeminal neuralgia (aka tic douloureux or Fothergill disease) can be extremely difficult to manage and can cause significant distress for patients with craniofacial pain. In this article, we will explore current treatment strategies to assist in treating patients with severe trigeminal neuralgia (TN).
TN is characterised by paroxysmal excruciating, electric like pain lasting a few seconds to minutes. It is often triggered by sensory stimulus: shaving, talking, eating, drinking, washing, cold wind etc. As a result this can have significant impact on quality ADLs such as severe difficulty eating leading to malnutrition and poor dental hygiene. There is no neurological deficits or detectable abnormality of the trigeminal nerve function. Patients can have pain free intervals lasting weeks to months however there is often a considerable fear of the pain returning.
It commonly involves one or more branches of the trigeminal nerve on one side of the face. Most commonly affected are the maxillary or mandibular branches. There is an annual incidence of 4/100,000 with highest incidence between 50-70 years of age. TN can be associated with MS in 2% of patients. Less than 5% can affect both sides of face and is more common in patients with MS.
There is still ongoing controversy concerning the exact pathophysiology. In classic TN, there can be vascular compression of the nerve at the root entry zone most likely by the superior cerebellar artery. An MRI head is the gold standard investigation to rule out other compressive causes on the trigeminal nerve such as tumour or multiple sclerotic plaque.
Treatment in the past was related to poor understanding of disease. Historical approaches include hot baths, rest in a dark room and ingestion of wine. The treatment of TN is firstly medical before considering surgical treatment. Primary medication is the use of carbamazepine and has been shown to provide complete or acceptable relief in 69-90% of patients. However there can be side effects that include drowsiness, dizziness, unsteadiness, N&V, rash, Steven-Johnson syndrome. Other medications include Phenytoin, Gabapentin, Lamotrigine, Valproic acid, Baclofen and Benzodiazepam.
The decision on which type of surgical approach is based on a variety of factors including patient’s age, medical conditions, and the pain severity. Surgery should be considered in cases of TN refractory to medical management or where significant side effect of medication is encountered. Surgical management includes:
- Peripheral nerve branch blocks or ablation
- Percutaneous trigeminal neurotomy (Stereotactic):
- Microvascular decompression (MVD)
- Total or partial transection of nerve.
- Stereotactic radiosurgery
Microvascular decompression (MVD) has become an accepted surgical technique for the treatment of TN, hemifacial spasm and glossopharyngeal neuralgia. The aim of surgery is to remove the vascular contact with the dorsal root of the trigeminal nerve. A retrosigmoid approach via a posterior fossa craniotomy is performed with the patient either in a park bench or lateral position. A piece of padding (Teflon) is often placed between the nerve and the vessel (Pic 1 & 2). Overall 70-80% of patients can become pain free post procedure. Barker et al reviewed 1185 patients, 70% of patients pain free without medications for TN 10 years postoperatively. Tronnier et al also showed excellent outcomes in 65% patients 10 years post MVD.
Patient with severe left sided trigeminal neuralgia. (Pic 1: above) shows superior cerebellar artery surgically moved away from the trigeminal nerve. (Pic 2: above) shows Teflon padding placed between nerve and vessel. Postoperatively patient had complete resolution of her trigeminal pain and was successfully weaned off all medications.
Percutaneous approaches include radiofrequency ablation, balloon compression and glycerol injection. The preferences for deciding on which percutaneous approach is often surgeon dependent. Overal initial success rate can be over 90% however patient can often experience excessive sensory deficit such as numbness as a main side effect. Overall recurrence rate is approximately 25%. Radiofrequency ablation has some distinct advantages over the other approaches. It can be administered as either pulsed or lesion. Intraoperative sensory and motor testing can be performed. The needle is smaller in callibre and therefore is less traumatic. It is performed as a day procedure and patients recover well to go home the same day.
(Pic 3): Lateral skull xray image of a percutaneous needle advancing through Foramen Ovale for radiofrequency pulsed ablation.
It is important to know that there are many surgical strategies available that can be effective in managing patient with severe TN in the event that medical management is refractory. Patients with severe TN require thorough consultation and with appropriate treatment can often lead to successful outcomes. This can result in significant positive impact on their overall quality of life. Many patients may also be able to reduce or stop the use of medication. All of the surgical treatment techniques described is available both publicly at the Royal Brisbane Hospital as well as privately through Brizbrain and Spine.
-By Doctor Norman Ma, Neurosurgeon