Greater, lesser and third occipital nerve entrapment: Sonographic anatomy and imaging

Occipital neuralgia causes stabbing, burning or throbbing pain and dysthesia in the distribution of the greater, lesser and third occipital nerves (ONs), which extends from the suboccipital region to the vertex of the head. There can be crossover between occipital neuralgia symptoms and headaches which can confuse the clinical picture. Ultrasound imaging can demonstrate the ONs, identify occipital neuropathy, including neural entrapment, and guide nerve blocks to address pain. The ONs are small, and muscles of the posterolateral neck signpost their position sonographically, however, the relative sonographic imaging appearances and anatomy of these muscles can be underappreciated, which can make imaging the ONs challenging. This review unpacks the relative sonographic anatomy of the ONs, including the postero-lateral neck muscles, and the sonographic technique to identify and image the muscles and ONs, including outlining points of ON entrapment.