Trigeminal neuralgia pain relief after gamma knife stereotactic radiosurgery

To report outcomes of patients with medical and/or surgical refractory trigeminal neuralgia (TN) treated with gamma knife stereotactic radiosurgery (GK SRS).

One hundred and forty-nine patients with 152 cases of TN treated with GK SRS were analyzed. All patients, except one, received a dose of 40Gy to the 50% isodose volume. The Barrow Neurological Institute (BNI) pain intensity score was used to grade pain. Actuarial rates of pain relief were calculated. Multiple factors were analyzed for association with pain relief.

The median follow up was 27 months (4-71 months). Overall 92% of cases achieved a BNI score I-III after GK SRS. Of those who had pain relief after GK SRS, 32% developed pain recurrence defined as a BNI score of IV or V. The actuarial rate of freedom from pain recurrence (BNI scores I-III) of all treated cases at 1, 2 and 3-years was 76%, 69% and 60%, respectively. On univariate analysis age ≥70 was predictive of better pain relief (p=0.046). Type of pain, prior surgery, multiple sclerosis, number of isocenters, treated nerve length, volume and thickness and distance from the root entry zone to the isocenter were not significant for maintaining a BNI score of I-III. Those who achieved a BNI score of I or II were more likely to maintain pain relief compared to those who only achieved a BNI score of III (93% vs 38% at three years, p<0.01). The rate of pain relief of twenty-seven patients who underwent repeat GK SRS was 70% and 62% at 1 and 2 years, respectively. Toxicity after first GK SRS was minimal with 25% of cases experiencing only new or worsening post-treatment numbness.

GK SRS provides acceptable pain relief with limited morbidity in patients with medical and/or surgical refractory TN.