Neurovascular compression of the greater occipital nerve: implications for migraine headaches.

BACKGROUND Surgical release of the greater occipital nerve has been demonstrated to be clinically effective in eliminating or reducing chronic migraine symptoms. However, migraine symptoms in some patients continue after this procedure. It was theorized that a different relationship between the greater occipital nerve and occipital artery may exist in these patients that may be contributing to these outcomes. A cadaveric investigation was performed in an effort to further delineate the occipital artery-greater occipital nerve relationship. METHODS Fifty sides of 25 fresh cadaveric posterior necks and scalps were dissected. The greater occipital nerve was identified within the subcutaneous tissue and its relationship with the occipital artery was delineated. A topographic map of the intersection of the two structures was created. RESULTS The greater occipital nerve and occipital artery have an intimate relationship, and crossed each other in 27 hemiheads (54.0 percent). The relationship between these structures when they crossed varied from a single intersection to a helical intertwining. CONCLUSIONS The greater occipital nerve and occipital artery have an anatomical intersection 54 percent of the time. There are two morphologic types of relationships between the structures: a single intersection point and a helical intertwining. Vascular pulsation may cause irritation of the nerve and is a possible explanation for migraine headaches that have the occipital region as a trigger point. Future imaging studies and clinical investigation is necessary to further examine the link between anatomy and clinical presentation.