Top 25 Cited Gamma Knife® Surgery Articles - Trigeminal Neuralgia

Object. The aim of this study was to identify pain relief and treatment morbidity following gamma knife radiosurgery (GKS) for idiopathic and secondary trigeminal neuralgia.

Methods. Between May 1992 and December 1999, 15 patients with idiopathic trigeminal neuralgia and 38 patients with secondary trigeminal neuralgia were treated with GKS. Pain improvement was achieved in 13 of the patients with idiopathic pain (pain response rate 86.7%). Seven patients were pain free and another six experienced pain reduction. There were no serious complications; however, two patients suffered a mild facial sensory change 8 months and 9 months, respectively, after GKS.

The patients with secondary trigeminal neuralgia were divided into two groups (Group I, 32 patients in whom the trigeminal root entry zone [REZ] near the tumor could not be visualized; and Group II, six patients in whom the trigeminal REZ near the tumor or brainstem lesion could be visualized).

In Group I, the pain subsided completely in eight patients and was reduced in seven (pain response rate 46.9%). In Group II, the pain subsided completely in one patient at 2.8 months and was reduced in three patients at a mean follow up of 0.8 months (range 0.6–1 month) after GKS. The pain response rate was 66.7%.

Conclusions. The authors believe that GKS is an effective treatment modalities for idiopathic and secondary trigeminal neuralgia, particularly in patients with inoperable lesions.

Object. The purpose of this study was to assess the efficacy of gamma knife radiosurgery (GKS) as the primary rather than secondary management for trigeminal neuralgia.

Methods. Eighty-two patients underwent GKS as their first neurosurgical intervention (Group A), and 90 patients underwent GKS following a different procedure (Group B). All GKS patients were treated with a maximum dose of 75 Gy. The single 4-mm isocenter was placed close to the junction of the trigeminal nerve and the brainstem. Six-month follow up was available for 126 patients and 12-month follow up for 84 patients.

Excellent (no pain and no medicine) or good (at least 50% reduction in pain and less medicine) relief was more likely to occur in Group A than in Group B patients 6 and 12 months following GKS for trigeminal neuralgia (p = 0.058). Excellent or good results were also more likely in patients with trigeminal neuralgia without multiple sclerosis (MS) (p = 0.042). The number and type of procedures performed prior to GKS, the interval between the last procedure and GKS, and the interval from first symptom to GKS (within Groups A and B) did not affect 6-month outcome. The interval between first symptom and GKS was shorter in Group A patients without MS (87 months) than in Group B (148 months; p < 0.004). There were no significant differences between Group A and B patients with regard to sex, age, or laterality.

Conclusions. Patients with trigeminal neuralgia who are treated with GKS as primary management have better pain relief than those treated with GKS as secondary management. Patients are more likely to have pain relief if they do not have MS.

Object. The purpose of this study was to assess the relationship between the volume of brainstem that receives 20% or more of the maximum dose (VB20) and the volume of the trigeminal nerve that receives 50% or more of the maximum dose (VT50) on clinical outcome following gamma knife radiosurgery (GKS) for trigeminal neuralgia (TN).

Methods. Patients with TN were treated with a single 4-mm isocenter with a maximum dose of 75 Gy directed at the trigeminal nerve close to where it leaves the brainstem. The VB20 and VT50, as determined on dose—volume histograms, were correlated with clinical outcomes at 6 and 12 months, laterality, presence of multiple sclerosis (MS), and each other.

At 6 months excellent pain relief (no pain or required medicine) was achieved in 27 of 48 patients (p = 0.009) when VB20 was greater than or equal to 20 mm³ and in 25 of 78 when VB20 was less than 20 mm³, when all patients are considered. At 12 months excellent pain relief was achieved in 16 of 32 patients (p = 0.038) when VB20 was greater than or equal to 20 mm³ and in 14 of 52 when VB20 less than 20 mm³, when all patients are considered. When VB20 was less than 20 mm³ in MS patients, five of 21 had an excellent result at 6 months and two of 13 at 12 months. The VB20 was 20 mm³ or more in 38 of 64 on the right side and in eight of 41 on the left side (p < 0.001) in patients with TN and without MS. There is a difference between left and right dose—volume histograms even when the same isodose is placed on the surface of the brainstem.

The VB20 was 20 mm³ or more in 45 of 105 patients with TN and without MS but in only three of 21 patients with TN and MS (p = 0.014). There was an inverse relationship between VB20 and VT50 (p = 0.01).

Conclusions. Isocenter proximity to the brainstem, as reflected in a higher VB20, is associated with a greater chance of excellent outcome at 6 and 12 months. Worse results in patients with TN and MS may be partly explained by a lower VB20.

Object. The purpose of this paper was to assess the treatment of trigeminal neuralgia (TN) with the higher than normal dose of 90 Gy.

Methods. Forty-two patients with typical TN were treated over a 3-year period with gamma knife radiosurgery. Every patient received a maximum dose of 90 Gy in a single 4-mm isocenter targeted to the root entry zone of the trigeminal nerve. Thirty of 42 patients had undergone no prior treatments. The median follow-up period was 14 months (range 2–30 months).

Thirty-one patients (73.8%) achieved complete relief of pain. Nine patients (21.4%) obtained good pain control. Complications were limited to increased facial paresthesia in seven patients (16.7%) and dysgeusia in four patients (9.5%).

Conclusions. The authors conclude that the use of 90 Gy is a safe and effective dose for the treatment of TN.

Object. Gamma knife radiosurgery (GKS) is being increasing performed in the management of patients with medically unresponsive trigeminal neuralgia. The authors report the results of repeated GKS in patients with recurrent facial pain after their initial procedure.

Methods. Between April 1997 and December 1999, 100 patients with idiopathic trigeminal neuralgia underwent GKS at the authors' center. To date, 26 patients have required additional surgery because GKS provided no significant pain relief (15 patients) or because they had recurrent facial pain (11 patients). Ten of these patients underwent repeated GKS at a median of 13 months (range 4–27 months). All patients undergoing repeated GKS had a significant reduction in their facial pain after the first procedure (eight were pain free); no patient developed facial numbness or paresthesias. Initially, nine of 10 patients became pain free 1 to 4 weeks following repeated GKS. At a median follow up of 15 months (range 3–32 months), eight patients remained pain free and required no medication. All eight patients with persistent pain relief developed minor neurological dysfunction after repeated GKS (six patients had facial numbness and two had paresthesias).

Conclusions. Repeated GKS can be associated with a high rate of pain relief for patients with trigeminal neuralgia who experienced a significant reduction in their facial pain after the first operation. However, every patient with sustained pain relief after the second operation also developed some degree of trigeminal dysfunction. These findings of improved pain relief for patients who develop facial numbness after GKS for trigeminal neuralgia support the experimental data currently available.

Object. Postherpetic neuralgia is a syndrome characterized by intractable pain. Treatment of this pain has not yet been successful. Patients with postherpetic neuralgia will therefore benefit from any progress in the treatment strategy. The authors performed gamma knife radiosurgery (GKS) as a noninvasive treatment for postherpetic trigeminal neuralgia (TN) and evaluated the success rate for pain relief.

Methods. Between 1995 and February 1999, six men and 10 women were treated for postherpetic TN; conservative treatment failed in all of them. The median follow up was 33 months (range 8–34 months). The radiation was focused on the root of the trigeminal nerve in the vicinity of the brainstem (maximal dose 70–80 Gy in one fraction, 4-mm collimator). The patients were divided into five groups according to degree of pain relief after treatment.

A successful result (excellent, very good, and good) was reached in seven (44%) patients and radiosurgery failed in nine (56%). Pain relief occurred after a median interval of 1 month (range 10 days–6 months). No radiation-related side effects have been observed in these patients.

Conclusions. These results suggest that GKS for postherpetic TN is a relatively successful and safe method that can be used in patients even if they are in poor condition. In case this method fails, other treatment options including other neurosurgical procedures are not excluded.

✓ A multiinstitutional study was conducted to evaluate the technique, dose-selection parameters, and results of gamma knife stereotactic radiosurgery in the management of trigeminal neuralgia. Fifty patients at five centers underwent radiosurgery performed with a single 4-mm isocenter targeted at the nerve root entry zone. Thirty-two patients had undergone prior surgery, and the mean number of procedures that had been performed was 2.8 (range 1–7). The target dose of the radiosurgery used in the current study varied from 60 to 90 Gy. The median follow-up period after radiosurgery was 18 months (range 11–36 months). Twenty-nine patients (58%) responded with excellent control (pain free), 18 (36%) obtained good control (50%–90% relief), and three (6%) experienced treatment failure. The median time to pain relief was 1 month (range 1 day–6.7 months). Responses remained consistent for up to 3 years postradiosurgery in all cases except three (6%) in which the patients had pain recurrence at 5, 7, and 10 months. At 2 years, 54% of patients were pain free and 88% had 50% to 100% relief.

A maximum radiosurgical dose of 70 Gy or greater was associated with a significantly greater chance of complete pain relief (72% vs. 9%, p = 0.0003). Three patients (6%) developed increased facial paresthesia after radiosurgery, which resolved totally in one case and improved in another. No patient developed other deficits or deafferentation pain. The proximal trigeminal nerve and root entry zone, which is well defined on magnetic resonance imaging, is an appropriate anatomical target for radiosurgery. Radiosurgery using the gamma unit is an additional effective surgical approach for the management of medically or surgically refractory trigeminal neuralgia. A longer-term follow-up review is warranted.