Wednesday, 20 November 2013

Clinic Speak: radiosurgery for trigeminal neuralgia

Gamma knife radiosurgery for MS-related trigeminal neuralgia #MSBlog #MSResearch #ClinicSpeak

"Pain is one of the most disabling symptoms MSers suffer from; it prevents normal functioning and stops MSers living normal lives. Pain can also make depression worse and frequently results in poor sleep that then exacerbates fatigue. All of this frequently triggers a downward spiral. MSers who have, or have had, trigeminal neuralgia know what I am talking about. Some of them describe it as the worst pain they have ever experienced and some contemplate suicide as a result of the pain. Due to its severity I personally treat MS-related trigeminal neuralgia as a medical emergency and do everything I possibly can to get the pain under control. It is most often due to a demyelinating plaque or lesion in the root entry zone, i.e. the area were the trigeminal nerve enters the brain stem. It usually responds, partially or completely, to drugs that block rapid firing of nerves in the demyelinated segment. The drugs we use belong to a class of agents called sodium channel blockers, for example carbamazepine, oxcarbazepine, phenytoin and gabapentin. In my experience carbamazepine and oxcarbazepine are the most effective drugs. Unfortunately they both come with side effects, in particular sedation and cognitive slowing. In most MSers the trigeminal neuralgia usually responds to these medications and resolves over 6-12 weeks. I also treat sudden-onset trigeminal neuralgia as a relapse and offer a course of high-dose steroids that in some cases helps with the pain. It is reassuring therefore that in MSers with refractory TN there is a non-invasive treatment that may help them. Gamma knife radiosurgery uses a technique of delivering high-dose radiation  to small area within the brain. In the case of TN is is delivered into the root entry zone and targets the nerve fibres as they enter the brain stem. This treatment seems to help and reduces the severity of the pain and renders over half of subjects pain-free. One of the side-effects is persistent numbness in the face that is due to permanent damage to those nerve fibers from the radiation therapy." 


Epub: Weller et al. Single-Institution Retrospective Series of Gamma Knife Radiosurgery in the Treatment of Multiple Sclerosis-Related Trigeminal Neuralgia: Factors that Predict Efficacy. Stereotact Funct Neurosurg. 2013 Nov 8;92(1):53-58.

Background: Gamma knife radiosurgery (GKRS) has been reported as a treatment option for multiple sclerosis (MS)-related trigeminal neuralgia.

Objective: To report the outcomes of a single-institution retrospective series of MS-related trigeminal neuralgia. 

Methods: Between 2002 and 2010, 35 patients with MS-related trigeminal neuralgia were treated with GKRS. The median maximum dose was 90 Gy. Data were analyzed to determine the response to GKRS and factors that may predict for efficacy.

Results: Of the 35 patients, 88% experienced pain at 3 months after GKRS. Kaplan-Meier estimates of 1-, 2- and 5-year freedom from pain relapse were 57, 57 and 52%, respectively. Numbness was experienced by 39% of patients after GKRS, though no patients reported bothersome numbness. Several differences were noted between how the MS-related variant responded to GKRS and what has previously been reported for idiopathic trigeminal neuralgia. These include the observations that development of post-GKRS numbness did not predict for treatment response (p = 0.62) and that dorsal root entry zone dose did not predict for freedom from pain relapse (odds ratio 1.01, p = 0.1). Active smoking predicted for freedom from pain relapse (odds ratio 67.4, p = 0.04). 

Conclusion: GKRS is a viable noninvasive treatment option for MS-related trigeminal neuralgia.

3 comments:

  1. "Due to its severity I personally treat MS-related trigeminal neuralgia as a medical emergency and do everything I possibly can to get the pain under control. It is most often due to a demyelinating plaque or lesion in the root entry zone, i.e. the area where the trigeminal nerve enters the brain stem."

    I am questioning your description of the location of the lesion. From my understanding, the more 'typical' trigeminal neuralgia is from a blood vessel rubbing against and demyelinating the nerve at the root entry zone. In MS, the demyelination happens in the brainstem. I am not a neurologist but I have read a lot and studied a lot on this specific topic.

    Thank you for bringing this topic up. It's important to me as I suffered a great deal with this pain but I had no other typical symptoms of MS, so my pain was called 'idiopathic' and the neurologist I was seeing didn't bother to look at the MRI he ordered because he had already decided I didn't have MS. I have since been fortunate to view the images of my MRI with a neuroradiologist who was able to identify at least two lesions in my right pons.

    I agree that it is a medical emergency. When I finally found a neurologist willing to listen and believe me, things turned around for me. I had a balloon compression rhizotomy as it was the best choice for me with all three branches of my trigeminal nerve affected.



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    1. Jennifer the root entry zone refers to area of the pons where the roots penetrate the pons. You are correct in that the MS lesion can be anywhere along the central tract of nerve from the root entry zone. The vascular compression typically affects the nerve rootlets on the surface of the pons before they enter the pons or just after they enter the pons, which is why lifting the blood vessel off the pons relieves the pain. MS usually causes atypical TN; i.e. there is often some associated loss of sensation or other signs to suggest a central brain stem lesion.

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  2. Thanks, Dr. Giovannoni -- I hadn't come back to this page until today to see your response. Thanks for explaining this to me. The neurologist I saw did say that my symptoms were 'unusual' but he didn't seem to be that interested in finding the cause. I sure wish he had been a little more curious or conscientious as I was in hell for over a year being treated like a psychiatric case. I recently had the chance to tell my story at an MS event in Vancouver where I live.

    https://www.youtube.com/watch?v=3qNRCd6TaBI

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