Transcript
First slide. First of all, I would like to thank the Scientific Committee as the chairman towards the parameters to present the result about radiosurgery with a very classic method using a frame and concerning drug-resistant essential trigeminal neuralgia. The primary objective of the study was to confirm the efficacy of the technique in comparison to other techniques. We have investigated if high dose applied to the plexus triangularis induce a decrease or cessation of pain attacks. The secondary objective was to confirm and to determine the safety and the predictive factors. Looking to the incidence of new functional disturbance of the fifth nerve and consequence of a previous surgical treatment to try to determine what is actual place of radiosurgery in the surgical strategy of trigeminal neuralgia. Can we consider this technique as a first-line technique alternative.
The criteria of selection for radiosurgery are classic criteria. We must have the certitude of the diagnostic, and we select the patient in function of the definition of the International Headache Society. The person must have a good answer to carbamazépine, no neurological deficit and a normal MRI. The drug resistance of the trigeminal neuralgia must be confirmed. That is a very important point. We must confirm that the prescription rules have been observed by examples of progressive step of the drug. We must be sure that the patient have used new antiepileptic in a good condition, and that the treatment was stopped by dose-related side effects or intolerance.
The patient must be also informed of all the surgical alternatives and choose this alternative with informed consent. The first question was to choose a good target. A lot of target that we propose from [inaudible 00:02:29] as proposed initially, a target exactly as the emergence of the nerve at the root entry zone. After, different group have proposed a more anterior target in the cisterna. And, finally, we have decided to use another target more anterior. Our target is not in the cisterna. The target we are using is exactly at the plexus triangularis. There are different argument in order to choose this target. First is a classic target that we use, where we are doing thermocoagulation. The tip of the electrode is usually in this place. Another argument that it was also the classic place for it [inaudible 00:03:26], and we have a very good bone, landmark exactly at this place. And the last argument, this target is very far from the brainstem, and we try to not have any side effect on the brainstem.
As you see in the planning, that is a target on axial view. The target on the sagittal view. Another patient with the target here, and the sagittal view is here. Concerning the techniques, it is very classic, one isocenter. What is important is the viability of the cisterna. And we try to give a theoretical dose of 90 Gy, but its maximum dose is always determined integrating measured dose at the brainstem. So, concerning the patient, we have treated 58 patients [inaudible 00:04:35] time, but we have only 39 patients with a follow-up of twelve months. So, this is a classic predominance of women, and, as you can see, the mean age is 70 years, and we have a woman of 109 years. And she was able to support during all months of frame without any problem. We have follow-up this patient one year and a half more, and she was totally pain-free of [inaudible 00:05:11.812] pain. So, there is no limit concerning the frame. The frame best technique.
So, the topography is a classic topography of the trigeminal neuralgia. The main duration before radiosurgery was nine years... 14, patients, that means 36 of the patients have had previous surgery. That is an important parameter because lots of studies have demonstrated that, in this situation, the results are poor, especially when before or after the percutaneous neurolysis, the patient different action in the trigeminal area. And we have four patients that, before the radiosurgery, have already an hypoesthesia.
Concerning the method, we have used [inaudible 00:06:05] collimator of four and six millimeters. The maximum dose was given in 15 patients. In 21, we delivered only 85 Gy. And in three, because they have very narrow cisterna, we are obliged to reduce the dose to 80. The median maximum dose was 86.5 Gy. If we can see there, the mean volume dose of the brainstem, we have, in three patients, less than 12 Gy for 1.5 mm3. That means that only that the dose inferior to 12 Gy was concerning 90%, for 90% of the patient, 0mm3. And the dose inferior to 10 Gy was concerning 60 patients. For 60 patients, 60% of the patients have absolutely no [inaudible 00:07:11.352] to the brainstem.
Concerning the results, we have used these outcome measures. The pain attacks and medications are classified in function of the attack reduction and the drug intake. That is a classic evaluation. We have also evaluated the clinical side effects by pin prick test, facial sensitivity, corneal reflex, etc. And, systematically, we have performed an MRI 6 months after the procedure. If we measure the target on all our patients, we have observed that our target is very interior. Is, as a mean, 12.5 mm from the emergence. And in comparison, we have compared our target to the group of [inaudible 00:08:10.367]. It was a very large experience with more than 30 [inaudible 00:08:14.969] patients treated.
The anterior target, the target anterior in the anterior part of the cisterna, there is a mean distance between the emergence and the target. It is 7 to 8 mm. So, our target is surely one of the most anterior used at the present time, exactly in the plexus triangularis. And perhaps one time in the future, we have progress of the MRI, we will be able to treat and fight selectively 5,1 or 5,3 neuralgia. As we do systematically MRI controls 6 months later, what we have observed in some cases the high signal on the target, as you can see here, or here in this case. And we never have observed any contrast enhancement on the brainstem. It was our objective, also.
Concerning the results, the main follow-up is 16 months. I know it's not enough, but we started 26 months ago, and we have selected patients with, at the minimum, 12 months of follow-up. The results must be appreciated. We have a longer follow-up of [inaudible 00:05:26] 12 exact results. The initial pain result at 6 months was 80% of good and excellent results. That means patients without attacks, without any attacks, and some patients with only a decrease of medication. The median delay after improvement was 20 days. That is classic. And also, like every center, we have observed an immediate pain relief in the night following the treatment. The late pain relief at the last follow-up decreased to 80%, 80% of good and excellent patients concerning 33 patients. Excellent pain free without medication in 17, with reduction of medication, but nonstop drugs in 16. We have observed failure in three patients, and two of these patients have multiple previous surgeries, and we have... is not statically enough, but we are very confident of this data. Two of these patients have received new treatment, and it is not logic to do a new thermocoagulation for this patient with previous surgery, but it was the only alternative.
Concerning the result, we have observed a new functional disturbance on the facial nerve in six patients. That means 15% of our patients. Non-painful hypoesthesia and paresthesia for two patients. Dysesthésia, who was transient Dysesthésia, in two, troublesome and always permanent with hypoesthesia in two other patients. Two of these patients have the dry eye. Reduction of corneal reflex was reported in one patient and a transient masseter weakness in one. You must note that three of three patients have multiple disturbances. We do not observe any anesthesia dolorosa or neuropathic pain, and no keratitis.
We have tried, on this table, to do a correlation between the complications observed in these six patients and some parameter preoperative or per operative. For example, we have tried to know if some patients have consequences of a previous surgery, and we have also measured the system in order to determine if the incidence of a narrow cistern is as a relationship with complications, and we have measured the distance between target and emergence and target and brainstem.
We have also measured the minimum dose volume for 50% of the cisternal trigeminal nerve and the volume brainstem dose superior to 10 Gy or to 12 or 10 Gy. And we tried to observe a correlation. For the first two patients, we have a good correlation. The first one has developed transient dysesthesia. This patient has three previous surgery. He has a very narrow cisterna, if you observe this data. He has a higher dose on the mean volume of 50%. We have the same correlation for the second one, and for the last one patient with hypoesthesia and corneal reflex. But for three other patients, we do not found any significant correlation.
In conclusion, Novalis radiosurgery with high doses is effective for drug-resistant essential trigeminal neuralgia. The anterior target on the plexus triangularis allows safe use of high doses with low rates of new facial nerve disturbance. That was our objective. The rate of failure is higher in patients with previously multioperated. We have reconfirmed this one on the clinical situation. Radiosurgery for trigeminal neuralgia in our practice can be indicated as first-line alternative before conventional percutaneous methods like radiofrequency thermocoagulation.
For young people or people without any surgical risk, that is a result of, as a consent, micro vascular decompression is still the gold standard. And, anyway, we need a more longer to follow-up, and we need to do a multicentric, randomized, controlled and comparative study in order to confirm this preliminary result. Thank you for your attention.
The criteria of selection for radiosurgery are classic criteria. We must have the certitude of the diagnostic, and we select the patient in function of the definition of the International Headache Society. The person must have a good answer to carbamazépine, no neurological deficit and a normal MRI. The drug resistance of the trigeminal neuralgia must be confirmed. That is a very important point. We must confirm that the prescription rules have been observed by examples of progressive step of the drug. We must be sure that the patient have used new antiepileptic in a good condition, and that the treatment was stopped by dose-related side effects or intolerance.
The patient must be also informed of all the surgical alternatives and choose this alternative with informed consent. The first question was to choose a good target. A lot of target that we propose from [inaudible 00:02:29] as proposed initially, a target exactly as the emergence of the nerve at the root entry zone. After, different group have proposed a more anterior target in the cisterna. And, finally, we have decided to use another target more anterior. Our target is not in the cisterna. The target we are using is exactly at the plexus triangularis. There are different argument in order to choose this target. First is a classic target that we use, where we are doing thermocoagulation. The tip of the electrode is usually in this place. Another argument that it was also the classic place for it [inaudible 00:03:26], and we have a very good bone, landmark exactly at this place. And the last argument, this target is very far from the brainstem, and we try to not have any side effect on the brainstem.
As you see in the planning, that is a target on axial view. The target on the sagittal view. Another patient with the target here, and the sagittal view is here. Concerning the techniques, it is very classic, one isocenter. What is important is the viability of the cisterna. And we try to give a theoretical dose of 90 Gy, but its maximum dose is always determined integrating measured dose at the brainstem. So, concerning the patient, we have treated 58 patients [inaudible 00:04:35] time, but we have only 39 patients with a follow-up of twelve months. So, this is a classic predominance of women, and, as you can see, the mean age is 70 years, and we have a woman of 109 years. And she was able to support during all months of frame without any problem. We have follow-up this patient one year and a half more, and she was totally pain-free of [inaudible 00:05:11.812] pain. So, there is no limit concerning the frame. The frame best technique.
So, the topography is a classic topography of the trigeminal neuralgia. The main duration before radiosurgery was nine years... 14, patients, that means 36 of the patients have had previous surgery. That is an important parameter because lots of studies have demonstrated that, in this situation, the results are poor, especially when before or after the percutaneous neurolysis, the patient different action in the trigeminal area. And we have four patients that, before the radiosurgery, have already an hypoesthesia.
Concerning the method, we have used [inaudible 00:06:05] collimator of four and six millimeters. The maximum dose was given in 15 patients. In 21, we delivered only 85 Gy. And in three, because they have very narrow cisterna, we are obliged to reduce the dose to 80. The median maximum dose was 86.5 Gy. If we can see there, the mean volume dose of the brainstem, we have, in three patients, less than 12 Gy for 1.5 mm3. That means that only that the dose inferior to 12 Gy was concerning 90%, for 90% of the patient, 0mm3. And the dose inferior to 10 Gy was concerning 60 patients. For 60 patients, 60% of the patients have absolutely no [inaudible 00:07:11.352] to the brainstem.
Concerning the results, we have used these outcome measures. The pain attacks and medications are classified in function of the attack reduction and the drug intake. That is a classic evaluation. We have also evaluated the clinical side effects by pin prick test, facial sensitivity, corneal reflex, etc. And, systematically, we have performed an MRI 6 months after the procedure. If we measure the target on all our patients, we have observed that our target is very interior. Is, as a mean, 12.5 mm from the emergence. And in comparison, we have compared our target to the group of [inaudible 00:08:10.367]. It was a very large experience with more than 30 [inaudible 00:08:14.969] patients treated.
The anterior target, the target anterior in the anterior part of the cisterna, there is a mean distance between the emergence and the target. It is 7 to 8 mm. So, our target is surely one of the most anterior used at the present time, exactly in the plexus triangularis. And perhaps one time in the future, we have progress of the MRI, we will be able to treat and fight selectively 5,1 or 5,3 neuralgia. As we do systematically MRI controls 6 months later, what we have observed in some cases the high signal on the target, as you can see here, or here in this case. And we never have observed any contrast enhancement on the brainstem. It was our objective, also.
Concerning the results, the main follow-up is 16 months. I know it's not enough, but we started 26 months ago, and we have selected patients with, at the minimum, 12 months of follow-up. The results must be appreciated. We have a longer follow-up of [inaudible 00:05:26] 12 exact results. The initial pain result at 6 months was 80% of good and excellent results. That means patients without attacks, without any attacks, and some patients with only a decrease of medication. The median delay after improvement was 20 days. That is classic. And also, like every center, we have observed an immediate pain relief in the night following the treatment. The late pain relief at the last follow-up decreased to 80%, 80% of good and excellent patients concerning 33 patients. Excellent pain free without medication in 17, with reduction of medication, but nonstop drugs in 16. We have observed failure in three patients, and two of these patients have multiple previous surgeries, and we have... is not statically enough, but we are very confident of this data. Two of these patients have received new treatment, and it is not logic to do a new thermocoagulation for this patient with previous surgery, but it was the only alternative.
Concerning the result, we have observed a new functional disturbance on the facial nerve in six patients. That means 15% of our patients. Non-painful hypoesthesia and paresthesia for two patients. Dysesthésia, who was transient Dysesthésia, in two, troublesome and always permanent with hypoesthesia in two other patients. Two of these patients have the dry eye. Reduction of corneal reflex was reported in one patient and a transient masseter weakness in one. You must note that three of three patients have multiple disturbances. We do not observe any anesthesia dolorosa or neuropathic pain, and no keratitis.
We have tried, on this table, to do a correlation between the complications observed in these six patients and some parameter preoperative or per operative. For example, we have tried to know if some patients have consequences of a previous surgery, and we have also measured the system in order to determine if the incidence of a narrow cistern is as a relationship with complications, and we have measured the distance between target and emergence and target and brainstem.
We have also measured the minimum dose volume for 50% of the cisternal trigeminal nerve and the volume brainstem dose superior to 10 Gy or to 12 or 10 Gy. And we tried to observe a correlation. For the first two patients, we have a good correlation. The first one has developed transient dysesthesia. This patient has three previous surgery. He has a very narrow cisterna, if you observe this data. He has a higher dose on the mean volume of 50%. We have the same correlation for the second one, and for the last one patient with hypoesthesia and corneal reflex. But for three other patients, we do not found any significant correlation.
In conclusion, Novalis radiosurgery with high doses is effective for drug-resistant essential trigeminal neuralgia. The anterior target on the plexus triangularis allows safe use of high doses with low rates of new facial nerve disturbance. That was our objective. The rate of failure is higher in patients with previously multioperated. We have reconfirmed this one on the clinical situation. Radiosurgery for trigeminal neuralgia in our practice can be indicated as first-line alternative before conventional percutaneous methods like radiofrequency thermocoagulation.
For young people or people without any surgical risk, that is a result of, as a consent, micro vascular decompression is still the gold standard. And, anyway, we need a more longer to follow-up, and we need to do a multicentric, randomized, controlled and comparative study in order to confirm this preliminary result. Thank you for your attention.