This study was conducted to evaluate the two main surgical modalities, microvascular decompression (MVD) and gamma-knife radiosurgery (GK), the treatment of trigeminal neuralgia (TN) and outline for an algorithm for the selection of these procedures. The authors have identified distinct differences in the two treatment groups and formulated a scale that predicts the outcome and satisfaction of patients who underwent the procedures. This series included 34 TN patients treated in 2000 and 2001 with MVD (19) and GK (15). Patients with TN associated with tumor or multiple sclerosis were excluded. Each patient's age, past medical history, clinical features of pain or pre-operative pain grade, duration of TN, medications, and prior surgical procedures were recorded. Long-term results were assessed by a structured interview by telephone. Clinical outcome was classified as excellent (complete relief without medications and numbness), good (complete relief without medications), fair (> 50% relief or with substantial numbness and weakness), or poor (< 50% relief or treatment failure). Patient self-rated satisfaction score was rated on a scale of 1 (unsatisfied) to 10 (completely satisfied). Statistical analysis was performed by paired t-tests and anova with post-hoc analysis by the Tukey-Kramer method. The median follow-up was 17 months (18 months for MVD and 16 months for GK). The average age of MVD patients was 61 years compared to 74 years for GK patients (p = 0.0005). In both groups there was a female majority (68% for MVD and 60% for GK). The latency between first symptom of TN and treatment procedure was 3.0 years for MVD and 3.9 years for GK (p > 0.05). There was no significant difference in pain grade between the two groups. The average TN complexity grade was significantly different between the two groups (3.0 for MVD and 5.8 for GK) (p < 0.001). Average response to procedure for MVD was 3.4 (good) and 2.4 (fair) for GK (p = 0.017). The satisfaction outcome for MVD was 8.7 compared to 6.4 for GK (p = 0.02). There was a significant correlation (r = -0.818, p < 0.001) between TN complexity grade and response. Additionally, a significant correlation between TN complexity grade and patient satisfaction was found (r = -0.763, p < 0.0001). The data here support the treatment algorithm employed by the senior author (JFA) of this study. The TN complexity grade accurately correlates with the patient's response and satisfaction to the surgical procedure. This complexity grade may be useful for patient counseling when choosing between treatment options.