Clinical outcomes after stereotactic radiosurgery for idiopathic trigeminal neuralgia

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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.

Once the diagnosis of trigeminal neuralgia is made, medical therapy becomes the initial approach for most patients. However, medical therapy in many patients fails or they cannot tolerate it, and eventually they require surgical intervention. In the past, surgery typically involved either MVD or one of several percutaneous ablative procedures.21 Although often associated with initial pain relief, all surgical procedures have variable but definite rates of recurrence and morbidity. The use of GKS has been advocated as a minimally invasive alternative surgical approach for treating trigeminal neuralgia. Stereotactic irradiation of the trigeminal ganglion was first reported by Leksell.18 More recently, several authors have reported their initial results with radiosurgery in which high-resolution image guidance is used.14,16,17,19,24,25,30,32 These data established the accuracy of radiosurgical targeting as well as the initial safety of the procedure, and provided dose—response information. Over the last 5 years, trigeminal nerve GKS has been performed at medical centers worldwide, with more than 2800 patients treated by December 1998 (unpublished data, Elekta Instruments, Inc., 1999). In this report we provide an independent evaluation of a large group of patients over an extended interval. To study the effectiveness of the procedure over time, we evaluated the latency to the patients' response, as well as the length and durability of pain relief. Our goal was also to identify those clinical factors associated with success or complications.

Clinical Material and Methods
Patient Population

Between December 1992 and December 1998, a total of 264 consecutive GKS procedures for trigeminal neuralgia were performed using the Leksell Gamma Knife Model A or B (Elekta Instruments, Atlanta, GA) at the University of Pittsburgh. Of these 264 procedures, 25 were performed for nonidiopathic trigeminal neuralgia (19 were associated with multiple sclerosis, three were secondary to tumors, and three were secondary to other pathological conditions such as a herpetic infection, Lyme disease, or Wallenberg's syndrome) and were therefore excluded from this study. Of the 239 procedures performed for idiopathic trigeminal neuralgia, 19 were repeated GKS after an initially successful procedure. For these 19 patients, the outcome after initial GKS was included in this study as a poor result and subsequent outcomes of the repeat procedure were excluded. Thus, 220 procedures in 220 patients were available for analysis. All 220 patients had trigeminal neuralgia that was idiopathic, longstanding, and refractory to medical therapy such as carbamazepine, phenytoin, baclofen, or gabapentin, as well as a variety of analgesic medications.

Of these 220 patients, 94 were men and 126 were women. The median age was 70 years (range 26–92 years). Most of the patients had a long history of medical treatment, with the median symptom duration being 96 months (range 3–564 months). Pain was predominantly distributed in the V2 and V3 distributions of the trigeminal nerve (29.5%), followed by V2 alone (22.3%), and V1 plus V2 (20.4%). Patients with V1 pain often underwent GKS as an alternative to other procedures. Although all patients reported the typical features of trigeminal neuralgia—a sharp, lancinating or shooting electric-shock type of pain triggered by a variety of events—16 (7.3%) noted additional features such as a more constant dull, aching, or burning pain. Eighty patients (36.4%) had some sensory disturbance (usually paresthesias) preoperatively, and three patients (1.4%) had partial deafferentation pain caused by earlier ablative procedures. The preoperative characteristics of our patients are summarized in Table 1.

TABLE 1

Preradiosurgery characteristics in 220 patients with trigeminal neuralgia

CharacteristicValue
age at radiosurgery (yrs) 
 median70 
 range26–92 
male/female94:126 
no. w/ each side of pain (%) 
 rt134 (60.9) 
 lt86 (39.1) 
duration of symptoms (mos) 
 median96 
 range3–564 
no. w/ each distribution of pain (%) 
 V19 (4.1) 
 V249 (22.3) 
 V329 (13.2) 
 V1+V245 (20.4) 
 V1+V31 (0.4) 
 V2+V365 (29.5) 
 V1+V2+V322 (10) 
no. w/ preop sensory complaints (%) 
 paresthesia80 (36.4) 
 deafferentation pain3 (1.4) 
additional atypical features (%)16 (7.3) 

Surgery had been performed previously in 135 (61.4%) of the 220 patients, and included MVD, glycerol rhizotomy, radiofrequency rhizotomy, balloon microcompression, peripheral neurectomy, or ethanol injections (Table 2). In these 135 patients, 86 (39.1%) underwent one, 39 (17.7%) underwent two, and 10 (4.5%) underwent three or more procedures before GKS. Thus, the majority of patients represented failures of both medical and surgical therapies. In the remaining 85 patients (38.6%), GKS was the first surgical procedure performed.

TABLE 2

Surgery before GKS for trigeminal neuralgia

FactorNo. of Patients (%)*
type of prior surgery 
 MVD74 (33.6) 
 glycerol rhizotomy71 (32.3) 
 radiofrequency rhizotomy29 (13.2) 
 balloon microcompression2 (0.9) 
 peripheral neurectomy3 (1.4) 
 ethanol block1 (0.5) 
no. of procedures 
  085 (38.6) 
  186 (39.1) 
  239 (17.7) 
 ≥310 (4.5) 

Some patients underwent more than one surgical procedure before GKS.

Radiosurgical Procedure

The Model A and B gamma knife units were used interchangeably for GKS at our center; the Model A was used in 122 patients (55.5%) and the Model B in 98 patients (44.5%). After application of the Leksell Model G stereotactic frame (Elekta Instruments) with patients receiving a local anesthetic, they underwent stereotactic MR imaging to identify the trigeminal nerve. Rarely patients underwent computerized tomography scanning for targeting if they were unsuitable for MR imaging. The MR studies were performed using contrast-enhanced, short repetition time sequences and axial volume acquisitions of 512 × 216 matrices divided into 1-mm slices. When the trigeminal nerve was difficult to identify on images (usually because of previous MVD), additional axial long relaxation time MR images were obtained. A single 4-mm isocenter was used in 192 patients (87.3%) and two 4-mm isocenters were used in 28 patients (12.7%). With a single isocenter, the target was 2 to 4 mm anterior from the junction of the trigeminal nerve and pons. The isocenter was usually located so that the brainstem surface was irradiated at the 30% isodose line. When two isocenters were used to create an oval dose plan, a longer nerve segment extending more anteriorly was irradiated. A randomized trial of one compared with two isocenters was performed within a two-institution protocol, and will be reported in a subsequent publication. We administered maximum doses of 60 (2.7%), 70 (24.1%), 75 (21.8%), 80 (48.6%), 85 (1.8%), and 90 Gy (0.9%). A team consisting of neurosurgeon, radiation oncologist, and medical physicist performed dose selection and planning. All patients left the hospital within 24 hours after GKS.

Follow Up and Statistical Analysis

All serial follow-up information was obtained from the patients or their referring physicians and included the degree of pain relief, latency interval to pain relief, need for further surgical procedures, use of medication, and complications. In addition, up-to-date clinical information was obtained for all 220 patients by telephone interviews conducted by physicians who were not involved in their treatment. To evaluate the effectiveness of the treatment over time (besides the typical measure of the proportion of patients with pain relief at initial or last follow up), we calculated the time to initial response from GKS and the duration of pain relief by using the Kaplan—Meier10 productlimit method. The time to onset of complications after GKS (new or increased sensory disturbance) was also calculated using the same methods. Pain relief duration was calculated from the time when the level of pain relief being studied (complete or > 50%) was achieved. Because patients who did not achieve pain relief were counted as relapsing at Time 0 and some patients with short follow up (6–36 months) still have a small chance of responding later, the actuarial estimates of pain relief duration may slightly underrepresent the proportion of patients achieving and maintaining pain relief. To identify any correlation of outcomes (that is, time to initial response, duration of benefit, and complications) with treatment parameters that included sex, age, duration of symptoms, presence or absence of preoperative paresthesia or additional atypical features, number of previous surgeries, maximum dose, and number of isocenters, stepwise (forward conditional) multivariate analyses in which the Cox proportional hazards model was used were performed.

Results
Pain Relief

The outcome of the intervention was graded into one of four categories: excellent, good, fair, and poor. Complete pain relief without the use of any analgesic medication was defined as an excellent outcome. We recommended that all patients with complete pain relief taper off their medications, and some patients were in the process of tapering at the time of evaluation (or refused to taper off because they feared a recurrence). Those patients with complete pain relief but who were still using some medication were considered to have good outcomes. Patients with partial pain relief (> 50% relief) were considered to have a fair outcome.16 No or less than 50% pain relief was considered to be a poor outcome. Placement within a category was decided by the patient rather than by the physician. Criteria for improvement included a reduction in both the frequency and severity of pain attacks. Of the 220 patients, 47 (21.4%) required additional surgical procedures because of poor pain control. Treatment in these patients was considered to have failed (poor outcome), and the results after the additional procedure were excluded from this analysis. Thus, although outcomes in 220 patients were calculated using actuarial statistics over a 6.5year period, the median follow-up duration was 2 years (median 22, range 6–78 months).

Most of the patients responded to GKS within 6 months of the procedure (median 2 months). The first evaluation was performed in all patients within 6 months after GKS. At the initial follow-up assessment, excellent results were obtained in 105 patients (47.7%), and excellent plus good results were seen in 139 patients (63.2%). Greater than 50% pain relief (excellent, good, or fair) was noted in 181 patients (82.3%). At the last follow-up evaluation, 88 patients (40%) had excellent outcomes, 121 (55%) had excellent plus good outcomes, and 152 (69.1%) achieved fair or better results. Thirty patients (13.6%) experienced recurrence of pain after initially achieving pain relief between 2 and 58 months after GKS (25 patients after complete relief, five after > 50% relief). Recurrences of pain occurred at a mean of 15.4 months after therapy.

Time to Initial Response

The time to response (achievement of pain relief) after GKS was analyzed using the product-limit method of Kaplan and Meier. The results are shown in Fig. 1. The median time to achieving greater than 50% pain relief (excellent, good, or fair) was 2 months (2 ± 0.05 months) and the median time to achieving complete pain relief (good or excellent) was also 2 months (2 ± 5.1 months). At 6 months after treatment, 81.4 ± 2.6% of patients had achieved greater than 50% pain relief, and by 1 year, 85.6 ± 2.5% had achieved this level of relief (actuarial statistics). Complete pain relief (good or excellent) was achieved in 64.9 ± 3.2% of the patients at 6 months, 70.3 ± 3.16% by 1 year, and in 75.4 ± 3.5% of patients by 33 months. Factors associated with time to response were determined by multivariate testing. The rate of achieving at least 50% pain relief was faster in patients with typical trigeminal neuralgia compared with patients who had additional atypical features (p = 0.025; Fig. 2). This factor was not significant for achieving complete pain relief (p = 0.21). Other clinical factors were not significant in univariate or multivariate analyses.

Fig. 1.
Fig. 1.

Actuarial plot showing the time to initial pain relief response after GKS for trigeminal neuralgia in 220 patients. Solid line represents the percentage of patients achieving greater than 50% pain relief; dotted line represents the percentage achieving complete pain relief.

Fig. 2.
Fig. 2.

Graph showing a comparison of the time to achieve greater than 50% pain relief in patients with purely typical pain (solid line, 204 patients) and in those with partly atypical pain (dotted line, 16 patients). The rate of achieving at least 50% pain relief was faster in patients with typical trigeminal neuralgia compared with patients who had additional atypical features (p = 0.025, multivariate analysis).

Duration and Maintenance of Pain Relief

The duration of pain relief after the initial response was also analyzed in all patients by using the Kaplan—Meier product-limit method (Fig. 3). For this analysis, the time interval before the initial response was omitted. The duration of pain relief was counted from the time the specified level of relief was achieved until either the pain recurred or until observation was censored at the last follow-up review. Patients who did not respond to GKS were recorded as having a relief duration of 0 months. Therefore, the first part of the Kaplan—Meier curve at Time 0 shows the percentage of patients who did not respond at all. Greater than 50% pain relief (excellent, good, or fair) was achieved and maintained in 75.8 ± 2.9% of patients at 1 year, 71.3 ± 3.3% of patients at 2 years, 67.2 ± 3.9% of patients at 3 years, 65.1 ± 4.3% of patients at 3.5 years, and 55.8 ± 9.4% of patients at 5 years. Complete pain relief (excellent or good) was achieved and maintained in 63.6 ± 3.3% of patients at 1 year, 59.2 ± 3.5% of patients at 2 years, 56.6 ± 3.8% of patients at 3 years, and 37.7 ± 15.6% of patients at 5 years. The 5-year result does not reflect current practice because most patients with 5-year follow up had undergone GKS in which a lower dose was delivered (60-65 Gy) than is presently used. A history of no previous surgery was the only factor significantly associated (p = 0.01) with achieving and maintaining complete pain relief (Fig. 4). The absence of preradiosurgery paresthesia, which is strongly correlated with no prior surgery (Table 3), was significantly associated (p = 0.024) with achieving and maintaining greater than 50% pain relief (Fig. 5). A history of no prior surgery was significant in univariate (p = 0.0284) but not multivariate modeling (p = 0.18) for achieving and maintaining greater than 50% pain relief.

Fig. 3.
Fig. 3.

Actuarial plots showing the percentage of 220 patients achieving and maintaining greater than 50% pain relief (solid line) and complete pain relief (dotted line). The 5-year results do not reflect current practice because in most patients with 5-year follow up, radiation was delivered at a lower dose (60–65 Gy) than that presently used.

Fig. 4.
Fig. 4.

Graph showing the percentage of patients achieving or maintaining complete pain relief who had no prior surgery (solid line, 85 patients) compared with those who had prior surgery (dotted line, 135 patients). A history of no prior surgery was the factor significantly associated with achieving and maintaining complete pain relief (p = 0.01, multivariate analysis).

TABLE 3

Correlation between number of prior surgeries and preoperative paresthesias

Preop Paresthesia
No. of Prior OpsNoYes
0805
14541
21425
≥319

Fig. 5.
Fig. 5.

Graph showing the percentage of patients achieving or maintaining greater than 50% pain relief who had no preradiosurgery paresthesia (dysesthesia; solid line, 140 patients ) compared with those with preradiosurgery paresthesia (dotted lines, 80 patients). The absence of preradiosurgery paresthesia was significantly associated with achieving and maintaining greater than 50% pain relief (p = 0.024, multivariate analysis).

Complication Rate

No patient sustained an early complication after a GKS procedure. Seventeen patients (7.7%) developed increased facial paresthesias and/or facial numbness that lasted longer than 6 months. One patient (0.4%) developed deafferentation pain after GKS. This patient had recurrent trigeminal neuralgia that had previously been treated by MVD. After her MVD procedure, she experienced some decrease in facial sensation, and her recurrent pain had some additional atypical features such as constant burning. Eight years after the initial surgery, GKS was performed to a maximum dose of 75 Gy by using two isocenters. Eight months later, the patient developed increased constant burning pain with numbness consistent with deafferentation pain.

No patient developed a mastication deficit after GKS or noted problems in facial motor function. The median time to developing paresthesias was 8 months (range 1–19 months; Fig. 6). After 19 months, no patient developed new sensory symptoms. Multivariate testing showed that the presence of a preradiosurgery sensory disturbance was important for developing an increased deficit following therapy (p = 0.01).

Fig. 6.
Fig. 6.

Actuarial plot showing the population of patients with new or increased postradiosurgery paresthesias over time. The median time to developing paresthesias was 8 months (range 1–19 months). After 19 months, no patient developed new sensory symptoms.

Discussion

Stereotactic GKS has been used increasingly since 1993 for the care of patients with trigeminal neuralgia.14,16,17,25,30,32 In this report, we detail the long-term outcomes in a large patient population. As in all GKS procedures, there is a latency interval for the expected response. This may be 2 to 3 years for an arteriovenous malformation, 6 months for schwannomas, or 2 to 4 months for a radiosurgical thalamotomy5,11,12,23 This is because the radiation effect is dependent on both acute and delayed changes in the target tissue.15,28,31 If the response is a positive one and pain is relieved, we must then determine the time course of the response, the degree of pain recurrence if observed, and the need for additional treatment.

Achievement of Pain Relief

Prior authors, including some in our group, have noted a latency interval to pain relief of approximately 1 to 2 months.16,17,32 In the present analysis, we found using actuarial statistics that 81.4 ± 2.6% of patients responded to treatment within 6 months (median 2 months). However, approximately 15% of patients experienced no improvement in their pain even after 12 months. Because no patient had achieved complete or greater than 50% pain relief after 1 year of follow up, we believe that patients whose pain was unchanged at 1 year cannot expect any improvement thereafter. In reality, this is an uncommon situation because most patients would not wait so long to attain pain relief. Patients who suffer continued disabling pain after GKS are treated with other surgical procedures. We advocate repeated GKS only if complete pain relief had been achieved initially, with subsequent recurrence.

Complete pain relief was achieved at a median time of 2 months (2 ± 5.1 months) with most patients achieving this level of relief within 6 months. Interestingly, another 10% of patients achieved complete pain relief 6 to 33 months after GKS. All of these patients obtained partial pain relief within 6 months and later had complete resolution of pain. Thus, it appears that patients with partial pain relief initially may go on to experience complete relief over time. This finding provides some ideas regarding the mechanism of response to GKS. Because most patients responded in the initial months, electrophysiological blocking of ephaptic transmission after nerve irradiation, which has been discussed as a possible mechanism by some authors,17,32 is possible. On the other hand, because some patients responded or improved in a later phase (> 6 months after GKS), a later radiation effect with axonal degeneration may be present.

The most important factor for a poor response to GKS was the presence of atypical pain features in addition to the typical neuralgic pain. Only 43.8 ± 12.4% of patients with atypical pain features responded at 6 months, whereas 84.4 ± 2.6% of patients with typical pain experienced relief. Such patients usually report a constant dull or burning pain, or a tingling sensation in addition to the typical features of trigeminal neuralgia. Generally, these patients' conditions tend to be refractory to any other surgical procedures. Because these atypical features may be related to varying degrees of underlying nerve injury, a procedure that causes additional axonal effects may provide no benefit.

Maintenance of Pain Relief

An analysis of the duration of pain relief begins with an assessment of patients who failed to gain any benefit. Fifteen percent of patients did not obtain greater than 50% pain relief and 25% did not obtain complete relief. For the entire series, 70% of patients achieved or maintained complete or greater than 50% relief at 2 years, and 55% maintained the relief 5 years after the time of the initial response. The rate of achieving and maintaining complete pain relief was 60% at 2 years and 40% at 5 years. Pain recurred in 30 patients (13.6% of the entire series; recurrence after partial pain relief was seen in five patients, and recurrence after complete pain relief was found in 25).

These results are not as good as those observed after MVD. Barker, et al.,1 in reporting on the series of 1185 patients studied by Lovely and Jannetta,20 found that complete pain relief was maintained in 70% of patients at 10 years. We continue to advocate MVD where appropriate for younger patients with trigeminal neuralgia because of the potential for a longer duration of pain relief. Nevertheless, the potential risks of MVD make it unsuitable for some patients. In addition, the benefit of MVD is reduced when performed a second time, or for recurrent trigeminal neuralgia. We consider GKS a good choice for patients with recurrent pain after MVD or percutaneous surgery has failed, even though previous surgical failure reduces the radiosurgical success rate.

Other investigators have reported long-term results following different percutaneous methods for trigeminal neuralgia. Percutaneous retrogasserian thermal rhizotomy was first described in 1974 by Sweet and Wepsic28 and has been performed widely. Broggi and coworkers,2 in a series of 1000 patients with a mean of 9.3 years of follow-up review, found an initial pain relief rate of 95%, with recurrence in 18.1%. In their series of 215 patients, Scrivani, et al.,26 reported that 83% maintained pain relief at a mean interval of 32 months. Percutaneous retrogasserian glycerol rhizotomy, first reported by Hakanson,8 is also widely used. Jho and Lunsford9 reported that 90% of 523 patients who underwent this procedure achieved complete pain relief initially and that 77% maintained long-term pain control, although sometimes requiring multiple procedures. The pain recurrence rate was estimated to be between 30% and 50% over 2 to 10 years. Others have reported a long-term pain control rate of 50 to 90%.6,7,27,28 Percutaneous balloon compression of the trigeminal nerve was first described in 1983.22 Recently, Brown, et al.,3,4 found that 94% of patients attained pain relief initially but that pain recurred in 26% (50 patients with an average 3-year follow up). Compared with percutaneous surgeries, the pain recurrence rate following GKS seems to be lower.

In our study, preoperative paresthesia and prior surgery were factors associated with duration of pain relief. These factors were well correlated with each other, as shown in Table 3. We believe that prior surgery may have injured the trigeminal nerve and caused a sensory disturbance. Sixty (70%) of 85 patients with no prior surgery maintained complete pain relief at 9 months and also at 5 years. We did not identify a recurrence in this group after 9 months. With this result, it is possible that primary GKS could provide a high rate of long-term pain control, as is found after MVD. This determination will require longer follow up. However, in patients with prior surgery, 60% maintained complete pain relief at 1 year, 53% at 2 years, and 33% at 5 years (although those with 5-year follow up received lower radiation doses). Considering that initial achievement of pain relief did not differ significantly between these groups (68% at 6 months and 76% at 1 year in patients with no prior surgery compared with 63% at 6 months and 70% at 1 year in patients with prior surgery, p = 0.42), the mechanism for achievement compared with maintenance of pain relief may be different. Generally, all secondary treatments for trigeminal neuralgia are associated with poorer results than after the first procedure. Perhaps those patients who require any kind of additional procedure have a more refractory form of the disorder.

Pain recurrence after GKS is likely the result of an incomplete effect on nerve tissue. Radiosurgery causes a partial axonal effect, as is found in an experimental primate model of trigeminal nerve GKS.13 This partial effect may be desirable to preserve facial sensation in most patients. Recurrent pain may develop because of incorporation of new afferent fibers, and the tendency to further aberrant axonal conduction or additional afferent propagation may be increased in patients in whom prior surgical procedures have failed, as a more severe form of trigeminal neuralgia. Such patients may experience a higher recurrence rate after GKS, as has been observed after other surgeries.

Safety of Radiosurgery

The low incidence of complications is the greatest advantage of stereotactic GKS compared with all other surgeries. Paresthesia or numbness of varying degrees is observed in 20 to 70% of patients after percutaneous thermorhizotomy, glycerol rhizotomy, or balloon nerve compression.1,2,4,6–9,20,22,26,28,29 In our study, 17 patients (10.2 ± 2.35% at 2 years) developed increased facial paresthesia and/or facial numbness, whereas only one patient (0.4%) developed deafferentation pain. The majority of our patients described their numbness or paresthesia as minor and not bothersome. Some authors have advocated percutaneous balloon nerve compression as advantageous for management of V1 trigeminal neuralgia, because of the lower risk for postoperative corneal analgesia.31,32 In the present study of the efficacy of GKS, no patient developed this complication. The reduced rate of facial sensory deficits or symptoms indicates that the effects on nerve tissue may be less pronounced than after other ablative surgeries. Thus, the mechanistic effect of GKS is likely a combination of both histological and electrophysiological responses.

No other complication, including keratitis, masseter weakness, or facial motor palsy, was found in this series. We found that the median time to developing paresthesias or numbness was 8 months (range 1–19 months) and that the risk of a late complication developing after 2 years appears to be minimal. Interestingly, this time course is similar after radiosurgery for vascular malformation or tumor.5,11,12,23 Multivariate analysis revealed that patients with a history of prior surgery or preoperative paresthesia were less likely to develop additional symptoms (p = 0.01 or p = 0.00, respectively). It may be that patients with prior paresthesia were at lower risk for developing increased paresthesias or did not notice subtle new changes.

In summary, our method of stereotactic GKS provided safe and effective management for many patients with disabling, typical trigeminal neuralgia. These results were achieved in a patient population with a high frequency of prior surgical intervention.

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    Scrivani JSKeith DAMathews ESet al: Percutaneous stereotactic differential radiofrequency thermal rhizotomy for the treatment of trigeminal neuralgia. J Oral Maxillofac Surg 57:1041121999J Oral Maxillofac Surg 57:

  • 27.

    Slettebø HHirschberg HLindegard KF: Long-term results after percutaneous retrogasserian glycerol rhizotomy in patients with trigeminal neuralgia. Acta Neurochir 122:2312351993Acta Neurochir 122:

  • 28.

    Sweet WHWepsic JG: Controlled thermocoagulation of trigeminal ganglion and rootlets for differential destruction of pain fibers. Part 1: Trigeminal neuralgia. J Neurosurg 40:1431561974J Neurosurg 40:

  • 29.

    Thompson TPMaitz AHKondziolka Det al: Radiation, radiobiology, and neurosurgery. Contemp Neurosurg 21:161999Contemp Neurosurg 21:

  • 30.

    Urgosik DVymazal JVladyka Vet al: Gamma knife treatment of trigeminal neuralgia: clinical and electrophysiological study. Stereotact Funct Neurosurg 70 (Suppl 1):2002091998Stereotact Funct Neurosurg 70 (Suppl 1):

  • 31.

    Van der Kogel AJ: Radiation-induced damage in the central nerve system: an interpretation of target cell responses. Br J Cancer 53 (Suppl 7):2072171986Van der Kogel AJ: Radiation-induced damage in the central nerve system: an interpretation of target cell responses. Br J Cancer 53 (Suppl 7):

  • 32.

    Young RFVermeulen SSGrimm Pet al: Gamma knife radiosurgery for treatment of trigeminal neuralgia: idiopathic and tumor related. Neurology 48:6086141996Neurology 48:

Article Information

Address reprint requests to: Douglas Kondziolka, M.D., Department of Neurological Surgery, Suite B-400, UPMC Presbyterian, 200 Lothrop Street, Pittsburgh, Pennsylvania 15213. email: kondziol@neuronet.pitt.edu.

© AANS, except where prohibited by US copyright law."

Headings

Figures

  • View in gallery

    Actuarial plot showing the time to initial pain relief response after GKS for trigeminal neuralgia in 220 patients. Solid line represents the percentage of patients achieving greater than 50% pain relief; dotted line represents the percentage achieving complete pain relief.

  • View in gallery

    Graph showing a comparison of the time to achieve greater than 50% pain relief in patients with purely typical pain (solid line, 204 patients) and in those with partly atypical pain (dotted line, 16 patients). The rate of achieving at least 50% pain relief was faster in patients with typical trigeminal neuralgia compared with patients who had additional atypical features (p = 0.025, multivariate analysis).

  • View in gallery

    Actuarial plots showing the percentage of 220 patients achieving and maintaining greater than 50% pain relief (solid line) and complete pain relief (dotted line). The 5-year results do not reflect current practice because in most patients with 5-year follow up, radiation was delivered at a lower dose (60–65 Gy) than that presently used.

  • View in gallery

    Graph showing the percentage of patients achieving or maintaining complete pain relief who had no prior surgery (solid line, 85 patients) compared with those who had prior surgery (dotted line, 135 patients). A history of no prior surgery was the factor significantly associated with achieving and maintaining complete pain relief (p = 0.01, multivariate analysis).

  • View in gallery

    Graph showing the percentage of patients achieving or maintaining greater than 50% pain relief who had no preradiosurgery paresthesia (dysesthesia; solid line, 140 patients ) compared with those with preradiosurgery paresthesia (dotted lines, 80 patients). The absence of preradiosurgery paresthesia was significantly associated with achieving and maintaining greater than 50% pain relief (p = 0.024, multivariate analysis).

  • View in gallery

    Actuarial plot showing the population of patients with new or increased postradiosurgery paresthesias over time. The median time to developing paresthesias was 8 months (range 1–19 months). After 19 months, no patient developed new sensory symptoms.

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Scrivani JSKeith DAMathews ESet al: Percutaneous stereotactic differential radiofrequency thermal rhizotomy for the treatment of trigeminal neuralgia. J Oral Maxillofac Surg 57:1041121999J Oral Maxillofac Surg 57:

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Slettebø HHirschberg HLindegard KF: Long-term results after percutaneous retrogasserian glycerol rhizotomy in patients with trigeminal neuralgia. Acta Neurochir 122:2312351993Acta Neurochir 122:

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Sweet WHWepsic JG: Controlled thermocoagulation of trigeminal ganglion and rootlets for differential destruction of pain fibers. Part 1: Trigeminal neuralgia. J Neurosurg 40:1431561974J Neurosurg 40:

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Urgosik DVymazal JVladyka Vet al: Gamma knife treatment of trigeminal neuralgia: clinical and electrophysiological study. Stereotact Funct Neurosurg 70 (Suppl 1):2002091998Stereotact Funct Neurosurg 70 (Suppl 1):

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Van der Kogel AJ: Radiation-induced damage in the central nerve system: an interpretation of target cell responses. Br J Cancer 53 (Suppl 7):2072171986Van der Kogel AJ: Radiation-induced damage in the central nerve system: an interpretation of target cell responses. Br J Cancer 53 (Suppl 7):

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Young RFVermeulen SSGrimm Pet al: Gamma knife radiosurgery for treatment of trigeminal neuralgia: idiopathic and tumor related. Neurology 48:6086141996Neurology 48:

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