Stereotactic radiosurgery for trigeminal neuralgia: outcomes and complications

Stereotactic radiosurgery is one of a number of recognised treatments for the management of trigeminal neuralgia refractory to drug therapy. The reported success of stereotactic radiosurgery in managing patients with trigeminal neuralgia varies in different units from 22 to 75%. This paper reports the outcomes of patients with trigeminal neuralgia who were treated at the National Centre for Stereotactic Radiosurgery in Sheffield, UK. The study reports the outcome of 72 patients treated consecutively between October 2004 and May 2008. Data were collected prospectively by a postal questionnaire sent to patients at 6, 12 and 24 months after treatment. The median age was 65.6 years (39 males: 33 females). Fourteen patients had secondary trigeminal neuralgia (eight multiple sclerosis). Fifteen of the patients included in the study were receiving a second treatment (an initial treatment having improved their pain significantly for at least 6 months). All radiosurgical procedures were performed using a single 4 mm collimator isocenter covering the region of the dorsal root entry zone with a maximal radiation dose of 80 Gy. The percentage of patients defined as having an excellent outcome (pain free without medication) was 39% after 6 months, 36% after 12 months and 64% after 24 months. The percentage of patients who reported being very satisfied with treatment was 71% after 6 months, 57% after 12 months and 53% after 24 months. Half the patients with secondary trigeminal neuralgia were pain free without medication after treatment, and 60% of patients who underwent a second treatment were pain free. A new trigeminal sensory deficit was reported by 31% of patients after radiosurgical treatment.     

Histologic analysis of a human trigeminal nerve after failed stereotactic radiosurgery: case report

BACKGROUND: Stereotactic radiosurgery is an accepted surgery to treat patients with medically intractable trigeminal neuralgia. However, little is known about the mechanism of pain relief after trigeminal neuralgia radiosurgery. We report the histologic findings of a human trigeminal nerve after failed radiosurgery for trigeminal neuralgia. CASE DESCRIPTION: A 74-year-old patient presented with a 10-year history of refractory trigeminal neuralgia. Prior surgeries included an MVD and PRGR. Gamma knife radiosurgery was performed targeting the proximal trigeminal nerve using one 4-mm isocenter (maximum dose, 85 Gy). She experienced good pain relief (no pain, reduced medications) for 16 months. She had no new trigeminal deficits after this procedure. The pain recurred, and she underwent repeat gamma knife radiosurgery targeting the distal trigeminal nerve using one 4-mm isocenter (maximum dose, 70 Gy). The pain continued to escalate until she required hospitalization for pain control and hydration. Three weeks after her second radiosurgical procedure, she underwent a repeat posterior fossa exploration. During that surgery, her trigeminal nerve was partially sectioned, and a small segment of the proximal to midcisternal nerve was sent for histological examination. There was no histologic evidence of nerve damage. CONCLUSION: This case supports the contention that trigeminal nerve injury is required to provide long lasting pain relief after trigeminal neuralgia radiosurgery.     

The effects of stereotactic radiosurgery on secondary facial pain

Twenty-seven patients with tumor-related secondary facial pain were treated by stereotactic radiosurgical procedures between November 1991 and October 1998. They had 14 meningiomas, 11 schwannomas (one trigeminal, 10 vestibular), one nasopharyngeal cancer and one chordoma. The mean maximum dose administered was 26.4 Gy (range 16 to 35 Gy) and the margin of the tumor was encompassed within the 45 to 90% isodose. The patients were analyzed based on their pain relief with a mean follow-up duration of 32.1 months. In 24 patients (85.7%), there was initial pain improvement after radiosurgery, but half had recurrent pain. A pain response was obtained in 12 cases (pain response rate = 42.9%), five were pain free and seven had pain reduction. On the follow-up MRI, a decrease in tumor volume of more than 20% of the preoperative volume occurred in 14 of 25 cases. The mean time interval to initial pain improvement (10.3 months) and pain response (5.7 months) were shorter than for a decrease in tumor volume (18.6 months). Tumor-related secondary facial pain was less responsive to stereotactic radiosurgery than idiopathic trigeminal neuralgia. It would seem that the mechanism of pain relief in radiosurgery is not only trigeminal root decompression secondary to tumor volume reduction, but also other mechanisms involving inactivation of abnormal electrical transmission may be involved.     

Evaluation of microvascular decompression and partial sensory rhizotomy in 252 cases of trigeminal neuralgia

Outcome after 252 posterior fossa explorations for the treatment of trigeminal neuralgia was determined by a retrospective review. Patients with distortion of the fifth nerve root caused by extrinsic vascular compression underwent microvascular decompression, those with no compression underwent partial sensory rhizotomy, and those with vascular contact but no distortion of the nerve root underwent decompression and rhizotomy. The mean follow-up period was 5.1 years. An excellent (75%) or good (8%) clinical outcome was achieved in 208 patients; 13 patients (5%) experienced little or no pain relief. Thirty-one patients (12%) suffered recurrent trigeminal neuralgia an average of 1.9 pain-free years after operation; recurrence continued at a rate of approximately 2% per year thereafter. Reoperation for recurrent or persistent pain provided excellent or good results in 85% of reoperated patients, but partial sensory rhizotomy was required in most of these patients. Outcome was affected by previous surgical procedures. A previous percutaneous radiofrequency lesion was associated with a significantly greater incidence of fifth nerve complications and a worse outcome after posterior fossa exploration. Because of this finding, the authors recommend that percutaneous radiofrequency rhizolysis be reserved for patients who have failed posterior fossa exploration or who are not candidates for surgery. Patients with compressive nerve root distortion and a short duration of symptoms before surgery had a significantly better outcome than patients with a longer duration of symptoms. In contrast, there was no relationship between the duration of symptoms and outcome of patients without nerve root distortion. Vascular decompression may cause dysfunction of the trigeminal system in tic douloureux, but in patients who remain untreated for long periods an intrinsic abnormality develops that may perpetuate pain even after microvascular decompression. Posterior fossa exploration is recommended as the procedure of choice for patients with trigeminal neuralgia who are surgical candidates.     

Percutaneous retrogasserian glycerol rhizotomy for treatment of trigeminal neuralgia

The treatment of trigeminal neuralgia by percutaneous retrogasserian glycerol rhizotomy was assessed in a series of 58 patients with a follow-up period ranging from 2 to 40 months postoperatively. All patients were considered medical failures prior to the procedure. Idiopathic trigeminal neuralgia was the diagnosis in 54 patients, and four patients had trigeminal neuralgia associated with multiple sclerosis. Forty-two patients (72%) reported complete relief from the procedure and are taking no medications. Four patients (7%) are much improved and require only minimal drug therapy. Twelve patients (21%) were considered treatment failures. The recurrence rate after initial relief of symptoms was 11%. Ten patients (17%) noticed a mild decrease in facial sensation following the procedure, and one additional patient had a profound sensory loss including loss of corneal reflex. The authors conclude that, while percutaneous retrogasserian glycerol rhizotomy may be useful in the treatment of trigeminal neuralgia, more clinical series and documentation of recurrence rate and complications are needed before any firm conclusions can be reached as to the efficacy of this therapy.     

Stereotactic radiosurgery for idiopathic trigeminal neuralgia

OBJECT: Each year a greater number of patients with trigeminal neuralgia (TN) undergo radiosurgery, including a large number of patients who are candidates for microvascular decompression (MVD). METHODS: The case characteristics and outcomes of 117 consecutive patients who underwent radiosurgery were retrieved from a prospectively maintained database. The mean patient age was 67.8 years; and the majority (58%) of patients had undergone surgery previously. The dependent variable for all analyses of facial pain was complete pain relief without medication (excellent outcome). Median follow-up duration was 26 months (range 1-48 months). The actuarial rate of achieving and maintaining an excellent outcome was 57% and 55% at 1 and 3 years, respectively, after radiosurgery. A greater percentage of patients who had not previously undergone surgery achieved and maintained excellent outcomes (67% at 1 and 3 years) than that of patients who had undergone prior surgery (51% and 47% at 1 and 3 years, respectively; relative risk [RR] = 1.77, 95% confidence interval [CI] 1.01-3.13, p = 0.04). New persistent trigeminal dysfunction was noted in 43 patients (37%). Tolerable numbness or paresthesias occurred in 29 patients (25%), whereas bothersome dysesthesias developed in 14 patients (12%). Only a radiation dose of 90 Gy correlated with new trigeminal deficits or dysesthesias (RR = 3.10, 95% CI 1.64-5.81, p < 0.001). Excellent outcomes in patients with new trigeminal dysfunction were achieved and maintained at rates of 76% and 74% at 1 and 3 years, respectively, after radiosurgery, compared with respective rates of 46% and 42% in patients who did not experience postradiosurgery trigeminal dysfunction (RR = 4.53, 95% CI 2.03-9.95, p < 0.01). CONCLUSIONS: Radiosurgical treatment provides complete pain relief for the majority of patients with idiopathic TN. There is a strong correlation between the development of new facial sensory loss and achievement and maintenance of pain relief after this procedure. Because the long-term results of radiosurgery still remain unknown, MVD should continue to be the primary operation for medically fit patients with TN.     

Percutaneous controlled radiofrequency trigeminal rhizotomy for the treatment of idiopathic trigeminal neuralgia: 25-year experience with 1,600 patients

OBJECTIVE: The objective of this study was to evaluate the effectiveness of percutaneous, controlled radiofrequency trigeminal rhizotomy (RF-TR). The outcome of 1,600 patients with idiopathic trigeminal neuralgia after RF-TR was analyzed after a follow-up period of 1 to 25 years. METHODS: A total of 1,600 patients with idiopathic trigeminal neuralgia underwent 2,138 percutaneous radiofrequency rhizotomy procedures between 1974 and 1999. Sixty-seven patients had bilateral idiopathic trigeminal neuralgia, and 36 of them were treated with bilateral RF-TR; 1,216 patients (76%) were successfully managed with a single procedure, and the remainder were treated with multiple procedures. Benzodiazepines and narcotic analgesics were used for anesthesia because patient cooperation during the procedures was essential so that the physician could create selective, controlled lesions. RESULTS: The average follow-up time was 68.1 +/- 66.4 months (range, 12-300 mo). Acute pain relief was accomplished in 97.6% of patients. Complete pain relief was achieved at 5 years in 57.7% of the patients who underwent a single procedure. Pain relief was reported in 92% of patients with a single procedure or with multiple procedures 5 years after the first rhizotomy was performed. At 10-year follow-up, 52.3% of the patients who underwent a single procedure and 94.2% of the patients who underwent multiple procedures had experienced pain relief; at 20-year follow-up, 41 and 100% of these patients, respectively, had experienced pain relief. No mortalities occurred. After the first procedure was performed, early pain recurrence (<6 mo) was observed in 123 patients (7.7%) and late pain recurrence was observed in 278 patients (17.4%). Complications included diminished corneal reflex in 91 patients (5.7%), masseter weakness and paralysis in 66 (4.1%), dysesthesia in 16 (1 %), anesthesia dolorosa in 12 (0.8%), keratitis in 10 (0.6%), and transient paralysis of Cranial Nerves III and VI in 12 (0.8%). Permanent Cranial Nerve VI palsy was observed in two patients, cerebrospinal fluid leakage in two, carotid-cavernous fistula in one, and aseptic meningitis in one. CONCLUSION: Percutaneous, controlled RF-TR represents a minimally invasive, low-risk technique with a high rate of efficacy. The procedure may safely be repeated if pain recurs.     

Gamma knife surgery for trigeminal neuralgia

OBJECT: Stereotactic radiosurgery is an increasingly used and the least invasive surgical option for patients with trigeminal neuralgia. In this study, the authors investigate the clinical outcomes in patients treated with this procedure. METHODS: Independently acquired data from 220 patients with idiopathic trigeminal neuralgia who underwent gamma knife radiosurgery were reviewed. The median age was 70 years (range 26-92 years). Most patients had typical features of trigeminal neuralgia, although 16 (7.3%) described additional atypical features. One hundred thirty-five patients (61.4%) had previously undergone surgery and 80 (36.4%) had some degree of sensory disturbance related to the earlier surgery. Patients were followed for a maximum of 6.5 years (median 2 years). Complete or partial relief was achieved in 85.6% of patients at 1 year. Complete pain relief was achieved in 64.9% of patients at 6 months, 70.3% at 1 year, and 75.4% at 33 months. Patients with an atypical pain component had a lower rate of pain relief (p = 0.025). Because of recurrences, only 55.8% of patients had complete or partial pain relief at 5 years. The absence of preoperative sensory disturbance (p = 0.02) or previous surgery (p = 0.01) correlated with an increased proportion of patients who experienced complete or partial pain relief over time. Thirty patients (13.6%) reported pain recurrence 2 to 58 months after initial relief (median 15.4 months). Only 17 patients (10.2% at 2 years) developed new or increased subjective facial paresthesia or numbness, including one who developed deaf-ferentation pain. CONCLUSIONS. Radiosurgery for idiopathic trigeminal neuralgia was safe and effective, and it provided benefit to a patient population with a high frequency of prior surgical intervention.     

Clinical outcomes after stereotactic radiosurgery for idiopathic trigeminal neuralgia

OBJECT: Stereotactic radiosurgery is an increasingly used and the least invasive surgical option for patients with trigeminal neuralgia. In this study, the authors investigate the clinical outcomes in patients treated with this procedure. METHODS: Independently acquired data from 220 patients with idiopathic trigeminal neuralgia who underwent gamma knife radiosurgery were reviewed. The median age was 70 years (range 26-92 years). Most patients had typical features of trigeminal neuralgia, although 16 (7.3%) described additional atypical features. One hundred thirty-five patients (61.4%) had previously undergone surgery and 80 (36.4%) had some degree of sensory disturbance related to the earlier surgery. Patients were followed for a maximum of 6.5 years (median 2 years). Complete or partial relief was achieved in 85.6% of patients at 1 year. Complete pain relief was achieved in 64.9% of patients at 6 months, 70.3% at 1 year, and 75.4% at 33 months. Patients with an atypical pain component had a lower rate of pain relief (p = 0.025). Because of recurrences, only 55.8% of patients had complete or partial pain relief at 5 years. The absence of preoperative sensory disturbance (p = 0.02) or previous surgery (p = 0.01) correlated with an increased proportion of patients who experienced complete or partial pain relief over time. Thirty patients (13.6%) reported pain recurrence 2 to 58 months after initial relief (median 15.4 months). Only 17 patients (10.2% at 2 years) developed new or increased subjective facial paresthesia or numbness, including one who developed deafferentation pain. CONCLUSIONS: Radiosurgery for idiopathic trigeminal neuralgia was safe and effective, and it provided benefit to a patient population with a high frequency of prior surgical intervention.     

Percutaneous retrogasserian glycerol rhizotomy for tic douloureux: Part 2. Results nd implications of trigeminal evoked potential studies

Trigeminal evoked potentials were recorded before and 6 weeks after a percutaneous retrogasserian glycerol rhizotomy was performed in 22 patients with tic douloureux. The latency of the trigeminal evoked potential (TEP) N20 peak and the sensory threshold to electrical stimulation of the maxillary gum were measured in each patient. The N20 latency differences between normal and affected sides for each patient were reduced after glycerol injection. Sensory thresholds were significantly different between the normal and the affected sides both before and after rhizotomy. These results were interpreted to indicate that glycerol more specifically affects the damaged myelinated axons implicated in the pathogenesis of trigeminal neuralgia. Of the 22 patients, 82% were either pain-free or significantly improved after operation. Postoperative normal N20 latencies were associated with pain relief in most cases. Our preliminary experience suggests that recurrent pain is more likely to develop in those patients whose postoperative TEP remains abnormal, especially if the abnormality cannot be ascribed to a prior surgical deafferentiation procedure. In addition to providing insight into the mechanism of pain relief, TEP measurements may help to predict the likelihood of long term relief after percutaneous retrogasserian glycerol rhizotomy.     

Microvascular decompression for trigeminal neuralgia in patients with multiple sclerosis

AIMS: To assess whether microvascular decompression (MVD) is a safe and efficacious treatment for patients with trigeminal neuralgia (TGN) and multiple sclerosis (MS). METHODS: Case records were reviewed of all patients with TGN and MS who underwent posterior fossa exploration with a view to MVD between 1993 and 2001. In all patients, magnetic resonance tomoangiography (MRTA) demonstrated vascular compression. RESULTS: Nine patients were included in the study. Seven patients underwent MVD alone; in 2 patients a partial sensory rhizotomy of the trigeminal nerve was added to the decompression. All patients had excellent initial pain relief. Recurrence of neuralgia was noted in 5 patients after MVD and in 1 of the 2 patients after partial sensory rhizotomy. Long-term pain relief was obtained in 1 patient who underwent a redo MVD after postoperative MRTA scans demonstrated recurrent vascular compression of the root entry zone (REZ). Thus only 4 out of 9 patients maintained pain relief. In addition, 3 patients experienced transient worsening of their MS. CONCLUSIONS: Although MVD provides good initial pain relief, the recurrence rate is much higher than that obtained in 'idiopathic' TGN. Although all procedures for the treatment of TGN are worse than those for idiopathic TGN, it is concluded that because of the high recurrence rate together with the morbidity associated with the procedure MVD should not be offered to patients with TGN and MS.     

Gamma knife radiosurgery for trigeminal neuralgia: the Washington University initial experience

Seventy-three patients were evaluated for the changes in pain relief, numbness and paresthesias after Gamma Knife radiosurgery to a maximum dose of 76-87 Gy for trigeminal neuralgia. Patients experienced pain relief as follows: 59% attained complete pain relief without prior surgery (33% with prior surgery); 25% achieved > or = 50% pain reduction (28% with prior surgery); 11% of surgery patients obtained minor pain relief, and 16% of patients without surgery had no relief (28% with prior surgery). Level of pain decreased rapidly within 6 weeks after radiosurgery. Numbness/paresthesias developed slowly over the first 12-15 months. Bothersome levels were experienced by 15% of the patients without prior surgery (22% with prior surgery). Comparison of the occurrence of numbness/paresthesias, with respect to prior surgery, was not statistically significant. Only 2% of all patients had persistently bothersome side effects. In conclusion, radiosurgery is an effective treatment of trigeminal neuralgia, especially for those patients not having prior surgery.     

Gamma knife radiosurgery for trigeminal neuralgia: experience at the Barrow Neurological Institute

Forty-three patients with trigeminal neuralgia (TN) unresponsive to pharmacologic treatment and/or prior invasive procedures underwent stereotactic radiosurgery with the Gamma Knife (GK). Outcome was evaluated by a standardized questionnaire mailed to each patient. The mean follow-up was 9 months. Fifteen patients (35%) reported no trigeminal pain and were no longer taking medication. Three patients (7%) experienced occasional pain, but were no longer taking medication. In 15 patients (35%), pain improved and was adequately controlled by medication, often in lower dosages than preoperatively. Pain was reduced in 9 patients (21%), but their symptoms were still inadequately controlled by drug therapy, and 1 patient (2%) reported no pain relief after treatment. Three patients (7%) described new facial numbness, but in none was this bothersome. GK radiosurgery for TN appears to have minimal morbidity, although the success rate may be slightly lower than that of other operative procedures. More patients and longer follow-up are needed before drawing final conclusions regarding efficacy and complications.     

Stereotactic radiosurgery for primary trigeminal neuralgia using the Leksell Gamma unit

OBJECTIVE: Previous papers have reported Gamma Knife radiosurgery to be a safe, effective method for primary trigeminal neuralgia. Since November 1996, we have treated primary trigeminal neuralgia using the Leksell Gamma Knife at the Tianjin Medical University. The present study reports clinical results of Gamma Knife radiosurgery in the treatment of trigeminal neuralgia in 80 cases. METHODS: The mean patient age was 67 years (range 32-92), the mean duration of facial pain was 7.6 years (range 1.5-29). The male:female ratio was 31:49. The right side of the face was involved in 45 patients (56.25%) and the left side in 30 cases (37.5%), with bilateral involvement in 5 cases (6.25%). Under local anesthesia, all patients underwent stereotactic MRI to identify the trigeminal nerve. A single isocenter, using a 4-mm collimator, was positioned at the sensory root of the trigeminal nerve entry zone of the pons, 4-6 mm from the brainstem surface, so that no more than the 20% isodose was administered to the brainstem. The maximum dose was between 70 and 90 Gy, with a mean of 75.6 Gy. For bilateral trigeminal neuralgia, two separate matrices were employed, and bilateral Gamma Knife radiosurgery was performed on the same day. RESULTS: Follow-up ranged from 12 to 43 months (mean 23.7 months). Neurological evaluation indicated excellent response in 42 cases (52.5%), good response in 25 cases (31.25%), effective response in 8 cases (10%), so the total pain control rate was 93.75%. The latency from Gamma Knife surgery to pain relief ranged from 1 to 120 days (mean 22 days). Among the 75 patients 7 with pain control experienced pain recurrence 5-26 months after being completely free from pain. A second Gamma Knife radiosurgery was performed in 7 recurrent cases and 5 patients with treatment failure. A maximal dose ranging from 70 to 80 Gy was given (mean 74.2 Gy). After a mean follow-up of 18 months (8-33 months), 9 patients achieved excellent results, and 2 had good results. The latency interval to pain relief ranged from 1 to 120 days (mean 15 days). Nine patients developed new facial numbness, while no other complication appeared in the remainder of the patients. CONCLUSIONS: Gamma Knife radiosurgery is a safe and effective method in the treatment of trigeminal neuralgia once diagnosis is established.     

Stereotactic radiosurgery using CT cisternography and non-isocentric planning for the treatment of trigeminal neuralgia.

OBJECTIVE: Frame-based radiosurgical rhizotomy has been shown in clinical studies to be effective for managing trigeminal neuralgia (TN). To date, however, only a small pilot study has been published for the frameless, image-guided CyberKnife system. We present our preliminary experience with 29 trigeminal neuralgia patients treated with the frameless CyberKnife using X-ray image-guided targeting, a novel CT method for target definition, and non-isocentric planning. MATERIALS AND METHODS: All 29 patients failed previous medical therapy and 14 had undergone prior surgical procedures. CT iohexal cisternography was used to identify the 6- to 8-mm segment of nerve to be lesioned. The marginal dose ranged from 60 to 70 Gy (median 66.4 Gy) as defined at an average 79th percentile. The corresponding Dmax varied from 71.4 to 86.4 Gy (median 77.91 Gy). RESULTS: After a median 10-month follow-up, 26 of 29 (90%) patients rated their pain control as excellent and 3 (10%) reported no improvement. Median time to improvement was 6 days. No or only minor progression in numbness was reported by 22 of 29 (76%) patients, 4 of 29 (14%) patients reported worsening, and 3 of 29 (10%) reported the onset of severe ipsilateral facial numbness. Two patients whose target volume inadvertently included the semi-lunar ganglion developed painful dysethesias in the distribution of their numbness. CONCLUSION: Although the optimal dose and length of nerve to be lesioned are still being refined, this preliminary experience suggests that image-guided robotic radiosurgery can effectively lesion the trigeminal nerve. Further follow-up is needed to determine whether our method has advantages over the more commonly used procedure for radiosurgical trigeminal rhizotomy.     

Neurovascular decompression with selective partial rhizotomy of the trigeminal nerve for tic douloureux

Fourteen patients with classic tic douloureux were treated with neurovascular decompression of the trigeminal nerve at its zone of entry into the pons. In addition, selective rhizotomy of the portio major was performed in each patient. This combined procedure gave excellent relief of pain with no recurrences in a 23-month postoperative period. Technical observations and postoperative complications in 3 patients are discussed. Routine selective partial rhizotomy of the sensory root of the trigeminal nerve may be a useful adjunct to neurovascular decompression for tic douloureux.     

Treatment of idiopathic trigeminal neuralgia: comparison of long-term outcome after radiofrequency rhizotomy and microvascular decompression

OBJECTIVE: To evaluate the long-term outcome of patients after either percutaneous trigeminal rhizotomy or microvascular decompression (MVD) for idiopathic trigeminal neuralgia at a single institution. METHODS: From 1977 to 1997, 316 radiofrequency lesion procedures and 378 MVDs were performed. Questionnaires were sent to all patients who were alive in 1981, 1982, 1992, and 1998. For all other patients, interviews were conducted with their relatives and general practitioners. A retrospective comparative analysis was performed with Kaplan-Meier probability curves as of the latest follow-up date. In addition, 80 patients who underwent MVD were examined postoperatively with quantitative sensory measurements by use of von Frey hairs. RESULTS: Two hundred twenty-five patients who underwent MVD and 206 patients who underwent radiofrequency could be analyzed retrospectively in detail. Overall, there was a 50% risk for recurrence of pain 2 years after percutaneous radiofrequency rhizotomy. Conversely, 64% of patients who underwent MVD remained completely pain free 20 years postoperatively. Patients without sensory impairment after MVD were pain free significantly longer than patients who experienced postoperative hypesthesia or partial rhizotomy. CONCLUSION: Because it is curative and nondestructive, MVD is considered the treatment of choice for trigeminal neuralgia in otherwise healthy people. In our study, it proved to be a more effective and long-lasting procedure for patients with typical trigeminal neuralgia than radiofrequency rhizotomy. Patients without postoperative sensory deficit remained pain free significantly longer, which is a strong argument against the "trauma" hypothesis of this procedure.     

Can fifth nerve mapping guide rhizotomy for recurrent trigeminal neuralgia? Case report

IntroductionMicrovascular decompression (MVD) is usually considered the first-line treatment for trigeminal neuralgia (TN) when medical treatments fail. Recurrence is rare and best treatment option is controversial. MVD was proposed as a feasible and effective technique for recurrent TN by many authors. Nevertheless, in a substantial number of cases, not any impingement or deterioration are found intraoperatively and partial selective rhizotomy is then advised. The rhizotomy site is mostly guided by anatomical landmarks, but variations due to scarring and adhesions are common pitfalls in these second surgeries. Intraoperative monitoring is infrequently used during MVD for trigeminal neuralgia. We describe the use of nerve mapping in a case of recurrence, revealing an unexpected rootlet distribution and thus safely guiding partial rhizotomy.Clinical presentationA 53-year-old woman had suffered from bilateral trigeminal neuralgia for 10 years. Symptoms began on the right side. MVD resolved her symptoms but, after a few months, she developed left TN which persisted after left MVD, radiofrequency and radiosurgery. She was referred to our center for a second MVD on the left side. Intraoperative inspection detected no relevant findings, and nerve mapping followed by partial selective rhizotomy was performed. Complete pain relief was achieved. There were no complications.ConclusionRhizotomy is seldom employed for refractory trigeminal neuralgia. The effects of previous treatments can jeopardize anatomical landmarks. Nerve mapping seems a promising tool to improve results.     

Linear accelerator radiosurgery using 90 gray for essential trigeminal neuralgia: results and dose volume histogram analysis

OBJECTIVE: To evaluate treatment of essential trigeminal neuralgia with 90 Gy delivered by a linear accelerator dedicated to radiosurgery. METHODS: This is a retrospective case series of 25 patients with essential trigeminal neuralgia treated from March 1999 to March 2001. All were treated with 90 Gy by means of a 5-mm collimator directed to the nerve root entry zone. Patient follow-up (range, 8-52 mo; median, 18 mo) was completed by an uninvolved party. Dose volume histograms of the brainstem were developed for the 20, 30, and 50% isodose lines by means of radiosurgery planning software. RESULTS: All patients obtained good to excellent pain relief with treatment. Nineteen (76%) of 25 patients achieved excellent pain relief (pain-free without medication). Six patients (24%) achieved good pain relief (50-90% reduction of pain with or without medication). Median time to pain relief was 2 months. Eight patients (32%) experienced relapse 4 to 13 months after treatment. Eight patients (32%) developed facial numbness, but none developed painful numbness. Mean brainstem volume within the 50% isodose line and occurrence of numbness was statistically significant (P = 0.03). There was no correlation between brainstem volume treated and outcome. CONCLUSION: Dedicated linear accelerator-based stereotactic radiosurgery that uses a 5-mm collimator to deliver 90 Gy to the nerve root entry zone is a safe and effective method for the treatment of essential trigeminal neuralgia. Care should be taken to limit brainstem volume included in the 50% isodose line in the treatment plan to avoid facial numbness.     

Long-term follow-up of trigeminal neuralgia treatment using a linear accelerator

While most of the studies examining radiosurgery for trigeminal neuralgia have used a Gamma Knife, a linear accelerator can also be utilized for treatment. We report on 20 patients with trigeminal neuralgia who received 23 treatments with a linear accelerator that delivered a maximum dose of 82.3-100 Gy. The median patient follow-up was 56.5 months, 70% of patients had received previous surgical treatment and 20% had secondary (nonessential) trigeminal neuralgia. Eight (35%) radiosurgery treatments resulted in complete pain relief; 5 (63%) patients with initial pain relief had pain recurrence at a mean time of 21.5 months. Ten (43%) patients reported a 50% or more decrease in pain severity but have not achieved a pain-free state. A total of 18 (78%) treatments resulted in no pain or a 50% or greater improvement in pain. Five treatments (22%) resulted in less than 50% improvement in pain. We conclude that linear accelerator stereotactic radiosurgery is a viable treatment option for trigeminal neuralgia patients, especially for patients who have not had a previous invasive treatment.