The relationship of dose to nerve volume in predicting pain recurrence after stereotactic radiosurgery in trigeminal neuralgia.

OBJECTIVE Approximately 75%-92% of patients with trigeminal neuralgia (TN) achieve pain relief after Gamma Knife surgery (GKS), although a proportion of these patients will experience recurrence of their pain. To evaluate the reasons for durability or recurrence, this study determined the impact of trigeminal nerve length and volume, the nerve dose-volume relationship, and the presence of neurovascular compression (NVC) on pain outcomes after GKS for TN. METHODS Fifty-eight patients with 60 symptomatic nerves underwent GKS for TN between 2013 and 2015, including 15 symptomatic nerves secondary to multiple sclerosis (MS). High-resolution MRI was acquired the day of GKS. The median maximum dose was 80 Gy for initial GKS and 65 Gy for repeat GKS. NVC, length and volume of the trigeminal nerve within the subarachnoid space of the posterior fossa, and the ratio of dose to nerve volume were assessed as predictors of recurrence. RESULTS Follow-up was available on 55 patients. Forty-nine patients (89.1%) reported pain relief (Barrow Neurological Institute [BNI] Grades I-IIIb) after GKS at a median duration of 1.9 months. The probability of maintaining pain relief (BNI Grades I-IIIb) without requiring resumption or an increase in medication was 93% at 1 year and 84% at 2 years for patients without MS, and 68% at 1 year and 51% at 2 years for all patients. The nerve length, nerve volume, target distance from the brainstem, and presence of NVC were not predictive of pain recurrence. Patients with a smaller volume of nerve (< 35% of the total nerve volume) that received a high dose (≥ 80% isodose) were less likely to experience recurrence of their TN pain after 1 year (mean time to recurrence: < 35%, 32.2 ± 4.0 months; > 35%, 17.9 ± 2.8 months, log-rank test, χ2 = 4.3, p = 0.039). CONCLUSIONS The ratio of dose to nerve volume may predict recurrence of TN pain after GKS. Prospective studies are needed to determine the optimal dose to nerve volume ratio and whether this will result in longer pain-free outcomes.

Quality of the Patient Experience during Radiosurgery: Measurement toward Improvement.

BACKGROUND: All physicians seek to improve the patient experience. In an awake surgical procedure, the patient has a unique opportunity to comment on all aspects of care. The provision of a positive experience is part of quality health care. Our purpose was to define this experience to determine areas for improvement. METHODS: We evaluated 125 patients who underwent stereotactic radiosurgery using a frame-based, gamma knife technique. Patients were surveyed by a nurse practitioner across all elements of their procedural experience prior to same-day discharge. RESULTS: The radiosurgery was completed in all patients with same-day discharge. In an initial 100-patient cohort, 89 patients said they had received adequate oral and/or intravenous sedation before the procedure. All 100 patients said that they felt comfortable before stereotactic frame application, and all patients later remembered frame application. These patients described frame application as very or adequately comfortable (n = 73), minimally uncomfortable (n = 18), or very uncomfortable (n = 9). Neuroimaging was described as very or adequately comfortable (n = 93), minimally uncomfortable (n = 3), or very uncomfortable (n = 4). Radiosurgery in the gamma knife unit was found to be very or adequately comfortable (n = 99) or very uncomfortable (n = 1). We evaluated how 8 separate factors may have contributed to survey responses related to procedural comfort. These factors included intravenous line placement, delivery of sedation medications, application of the head frame, having the MRI, having radiosurgery on the gamma knife bed, removal of the stereotactic frame, communication with caregivers, and knowing what to expect beforehand. We asked the patients to rate their nursing care during the radiosurgery experience, and 'excellent' was chosen by all initial 100 patients. Other elements of the procedure were also studied as well as suggestions for improvement. As a secondary objective, we then modified our protocol to include sodium bicarbonate added to the local anesthetic for frame application and evaluated an additional cohort of 25 patients. CONCLUSIONS: Utilizing a system of physician and nursing education, together with pharmacological sedation and efficient procedural steps, patients said that intravenous line placement (91%), stereotactic frame application (74%), MRI (93%), receiving radiosurgery in the unit (99%), frame removal (84%), communication with caregivers (100%), and knowing what to expect beforehand (97%) were either very or adequately comfortable. Specific evaluations of care processes can lead to care improvement.