Background: Surgical treatment of migraines at various trigger sites has been shown to significantly reduce migraine frequency, intensity and duration. The purpose of this study is to identify factors which contribute to migraine headache surgery failure.

Methods: A retrospective chart review was performed on all patients who underwent surgery for migraines by the senior author from January 1, 2001 through December 31, 2008. The study population was subdivided into two groups: surgery success and surgery failure. All patients had at least 1 year of postoperative follow up, and all patients completed a detailed migraine-specific questionnaire as part of follow-up. The patient's chart and questionnaires were analyzed retrospectively. 36 unique data points were collected for each patient, including demographics; pre –and post-operative migraine details; intra-and post-operative course; and outcome variables.

Results: 382 patients underwent migraine surgery by the senior author between January 1, 2001 and December 31, 2008. 102 patients met inclusion and exclusion criteria. 66 patients were in the migraine surgery success group, defined as complete elimination of migraine headaches postoperatively. 36 patients were in the migraine surgery failure group, defined as <50% reduction in frequency, intensity or duration of migraines postoperatively. Significant differences between surgery success group (S) and surgery failure (F) groups are: age of onset of migraines (S:25.4±11.4 years versus F:20.5±10.3 years, p=0.04); frequency of intra-operative complications (S:0% versus F:9.1%, p=0.04); surgery at site I (S:83.3% versus F: 50%, p=0.0006) or site II (S:75.8% versus F:50%, p=0.015); only one surgical site (S:24.2% versus F: 52.8%, p=0.0048); 1-2 surgical sites (S:50.0% versus F:72.2%, p =0.04); and four surgical sites (S:34.7% versus F: 8.3%, p = 0.04). History of head or neck injury (S:15.9% versus F:33.3%, p=0.08); associated motor symptoms (S:26.6% versus F:44.4%, p=0.08); and sensory triggers (S:82.8% versus F:94.4%, p=0.13) appeared to differ between the two groups, but were not statistically significant.

Conclusions: Factors associated with migraine surgery failure are younger age of migraine onset, intra-operative complications, and two or fewer surgical sites. Factors associated with migraine surgery success are surgery at site I or II, and all four surgical sites. Recognition of the factors contributing to failure will lead to further analysis of the reasons for the undesirable outcomes and thus possible further improvement of the results.