Trigeminal Neuralgia - Research Support

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Clin J Pain 2002 Jan-Feb;18(1):42-7

Stereotactic radiosurgery for the treatment of trigeminal neuralgia.
Kondziolka D, Lunsford LD, Flickinger JC.

Department of Neurological Surgery, University of Pittsburgh, and the Center for Image-Guided Neurosurgery, Pittsburgh, Pennsylvania, USA. kondziol@neuronet.pitt.edu

Stereotactic radiosurgery is an increasingly used and the least invasive surgical option for patients with medically refractory trigeminal neuralgia (TN). The authors began use of this technique at our center in 1992 and have evaluated outcomes serially. Independently acquired data from 220 patients with idiopathic TN that had Gamma Knife radiosurgery was reviewed. The median radiosurgery dose was 80 Gy with a range of 60 to 90 Gy. Most patients had features of typical TN, although 16 (7.3%) described additional atypical features. One hundred thirty-five patients (61.4%) had prior surgery.

Patients were followed to a maximum of 6.5 years (median, 2 years). Complete or partial pain 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% patients at 33 months. Patients with an atypical pain component had a lower rate of achieving pain relief ( p = 0.025). Due to recurrences, 55.8% of patients had complete or partial pain relief at 5 years. The absence of preoperative sensory disturbance or prior surgery correlated with an increased proportion of patients in complete or partial pain relief over time. Ten percent of patients developed new or increased subjective facial paresthesia or facial numbness.

Radiosurgery for idiopathic TN was safe and effective, and provided benefit to a patient population with a high frequency of prior surgical intervention. It is an important addition to the surgical armamentarium for TN.

Int J Radiat Oncol Biol Phys 2000 Jul 1;47(4):1013-9
Abstract

Gamma knife radiosurgery for trigeminal neuralgia: the initial experience of The Barrow Neurological Institute.
Rogers CL, Shetter AG, Fiedler JA, Smith KA, Han PP, Speiser BL.

St. Joseph's Hospital and Barrow Neurological Institute, Phoenix, AZ, USA. lelandroge@aol.com

PURPOSE: To assess the efficacy and complications of Gamma Knife radiosurgery for trigeminal neuralgia.

METHODS AND MATERIALS: The Barrow Neurological Institute (BNI) Gamma Knife facility has been operational since March 17, 1997. A total of 557 patients have been treated, 89 for trigeminal neuralgia (TN). This report includes the first 54 TN patients with follow-up exceeding 3 months. Patients were treated with Gamma Knife stereotactic radiosurgery (RS) in uniform fashion according to two sequential protocols. The first 41 patients received 35 Gy prescribed to the 50% isodose via a single 4-mm isocenter targeting the ipsilateral trigeminal nerve adjacent to the pons. The dose was increased to 40 Gy for the remaining 13 patients; however, the other parameters were unvaried. Outcome was evaluated by each patient using a standardized questionnaire. Pain before and after RS was scored as level I-IV per our newly-developed BNI pain intensity scoring criteria (I: no pain; II: occasional pain, not requiring medication; III: some pain, controlled with medication; IV: some pain, not controlled with medication; V: severe pain/no pain relief). Complications, limited to mild facial numbness, were similarly graded by a BNI scoring system.

RESULTS: Among our 54 TN patients, 52 experienced pain relief, BNI score I in 19 (35%), II in 3 (6%), III in 26 (48%), and IV in 4 (7%). Two patients (4%) reported no relief (BNI score V). Median follow-up was 12 months (range 3-28). Median time to onset of pain relief was 15 days (range 0-192), and to maximal relief 63 days (range 0-253). Seventeen (31%) noted immediate improvement (</= 24 h). Prior to RS, all patients were on pharmacologic therapy felt to be optimal or maximal. Twenty-two (41%) were able to stop medications entirely (BNI score I or II). Another 16 (30%), with BNI Score III relief, decreased medication intake by at least 50%. Patients with classical TN pain symptoms were more likely to stop medications than those with atypical features, 49% (21 of 43) versus 9% (1 of 11). This difference was significant at p = 0.040. Statistically, the finding most predictive for pain relief was new facial numbness following RS. Each of the 5 patients with new numbness after RS developed BNI score I relief, contrasting with 35% for the 49 patients with no new numbness (p = 0.019). Complications have been limited to delayed, mild facial sensory loss. Before RS, 17 patients had numbness from prior invasive procedures, none of whom reported a worse numbness score after treatment. Thirty-seven patients had no facial numbness at the time of RS, of whom 5 developed facial hypesthesia. Each rated this as "mild, not bothersome." There have been no other sequellae.

CONCLUSION: RS is an effective treatment, and is the least invasive nonpharmacologic therapy for TN. It carries a small risk of mild facial hypesthesia, a side effect which, somewhat ironically, may be desirable, because it appears to correlate favorably with an excellent pain response. We currently include radiosurgery among the appropriate options for TN patients who have failed optimal medical management, with or without prior invasive neurosurgical procedures. We present here BNI scoring systems for pain intensity and facial numbness. These have proved simple and reliable, have facilitated data collection, rendered analysis more objective, and improved our ability to discuss results with patients and colleagues.

PMID: 10863073 [PubMed - indexed for MEDLINE]

Neurology 1997 Mar;48(3):608-14

Comment in:
Neurology. 1997 Mar;48(3):565-6.
Neurology. 1998 Apr;50(4):1193-4.

Gamma Knife radiosurgery for treatment of trigeminal neuralgia: idiopathic and tumor related.
Young RF, Vermeulen SS, Grimm P, Blasko J, Posewitz A.

Northwest Neurosciences Institute and Gamma Knife Center Northwest Hospital, Seattle, WA 98133, USA.

Sixty patients with trigeminal neuralgia who did not have a response to pharmacologic treatment (including 22 who had no response to conventional surgical treatment) underwent stereotactic radiosurgical treatment with the Leksell Gamma Knife.

METHOD: A radiosurgical maximum dose of 70 Gy was delivered to the trigeminal nerve root adjacent to the pons via a 4-mm collimator helmet in 51 patients who presented with trigeminal neuralgia unrelated to tumors. In these patients, the root was localized by stereotactic MRI. Follow-up assessment of pain relief was accomplished by a third party not involved in the patients' clinical care.

RESULTS: Within a latency period of 1 day to 4 months following the treatment, 38 of 51 patients (74.5%) were completely free of pain and eventually all medications were tapered off. An additional seven patients (13.7%) experienced reductions in pain from 50 to 90% and utilized little or no medications. Patients who had no prior surgical intervention fared much better than those who had previous surgery to relieve their facial pains. At last follow-up, a mean of 16.3 months (range 6-36 months) after treatment, 41 patients (80.4%) remained pain-free or had marked pain reduction. There were four patients with recurrent pain. All 26 patients with classical symptoms of trigeminal neuralgia with no atypical features who had no prior surgery, had complete or nearly complete pain relief, and none of these patients had recurrent pain. Nine patients with trigeminal neuralgia due to tumors received standard radiosurgical treatment directed at their tumors, and eight of nine (88.8%) had pain relief. Of the total of 60 patients treated for trigeminal neuralgia, 49 (81.7%) experienced complete or nearly complete relief of pain at last follow-up. Only one patient with pre-existing facial sensory loss due to a tumor had a mild increase in facial numbness. No other patient experienced either loss of facial sensation or any other complication.

CONCLUSION: Gamma Knife radiosurgery appears to be a minimally invasive, safe, and effective therapy of trigeminal neuralgia.

PMID: 9065534 [PubMed - indexed for MEDLINE]