Analysis Of Factors Predicting For Pain Resolution After Gamma Knife Radiosurgery For Medically Refractory Trigeminal Neuralgia

Cartier L. Jacqueline1, Inga S. Grills2, Peter Chen2, Hong Ye2, Ann Maitz2, Larry L. Kestin2, Daniel J. Krauss2, Lucia Zamorano3, Rick Olson2, Daniel Pieper.2

1Wayne State University School of Medicine 2 William Beaumont Hospital 3Michigan Brain & Spine Surgery Center

Keywords: trigeminal neuralgia, pain, gamma knife, outcome, cranial nerve

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     To evaluate the clinical outcomes of patients undergoing Gamma Knife (GK) stereotactic radiosurgery as a non-surgical treatment for trigeminal neuralgia (TGN).
     Ninety-five patients underwent GK for TGN between 12/2006 and 6/2009 at William Beaumont Hospital. Eighty had follow-up > 6 weeks and were the subject of this report. Median patient age was 68 years (50-92); 58 female, 22 male. 74% of patients had typical trigeminal pain, 11% had atypical features and 11% multiple sclerosis. Thirty patients (38%) had undergone prior surgical procedures and 37 (46%) had pre-existing sensory complaints.
     The median dose delivered was 40 Gy (range: 35-45 Gy) at the 50% isodose line using either a single (85%) or two (6%) isocenters with the 4 mm diameter collimator, or two isocenters with a 4 mm and 8 mm collimator helmet (9%). Patients were seen within 2 weeks post-GK and then every 3-6 months in addition to periodic mail surveys and telephone interviews. Multiple patient and treatment-related factors were analyzed for association with pain relief. Mean follow-up duration was 14.7 months.
     91% of patients (n=73) reported at least partial pain resolution: 45% (n=36) complete pain relief, 46% (n=37) partial relief. The median time to pain resolution was 23 days. Seventeen patients (23%) who had partial to complete resolution had pain recurrence (median: 6.3 months). The pain recurrence rate was higher in patients with MS (44% versus 20%). Sixteen (20%) patients reported new post-treatment sensory complaints; no other complications were noted. We identified that the greater the treated nerve length, the greater the probability of achieving BNI of I-II (p=0.021) and for resolution to be experienced (p=0.037). The cut-point length for partial/complete relief was a treated length of 0.51cm.
     This is a retrospective study.
     In this study, GK radiosurgery for trigeminal neuralgia was associated with complete or partial pain resolution in 91% of patients. Longer treated nerve length was associated with better pain resolution.
     Although 23% of patients had pain recurrence after GK, the initial success and recurrence rates appear similar to those reported after percutaneous treatment approaches with minimal post-treatment neurological complaints. Additional follow-up will be required to assess the durability of relief.


Project Roles:

C. Jacqueline (), I. Grills (), P. Chen (), H. Ye (), A. Maitz (), L. Kestin (), D. Krauss (), L. Zamorano (), R. Olson (), D. Pieper. ()