Ultrasound-Guided Intermediate Site Greater Occipital Nerve Infiltration: A Technical Feasibility Study.

BACKGROUND Two studies recently reported that computed tomography (CT) guided infiltration of the greater occipital nerve at its intermediate site allows a high efficacy rate with long-lasting pain relief following procedure in occipital neuralgia and in various craniofacial pain syndromes. OBJECTIVE The purpose of our study was to evaluate the technical feasibility and safety of ultrasound-guided intermediate site greater occipital nerve infiltration. STUDY DESIGN Retrospective study. SETTING This study was conducted at the imaging department of a 1,409 bed university hospital. METHODS Local institutional review board approval was obtained and written consent was waived. In this retrospective study, 12 patients suffering from refractory occipital neuralgia or craniofacial pain syndromes were included between April and October 2014. They underwent a total of 21 ultrasound-guided infiltrations. Infiltration of the greater occipital nerve was performed at the intermediate site of the greater occipital nerve, at its first bend between obliqus capitis inferior and semispinalis capitis muscles with local anestetics and cortivazol. Technical success was defined as satisfactory diffusion of added iodinated contrast media in the fatty space between these muscles depicted on control CT scan. We also reported first data of immediate block test efficacy and initial clinical efficacy at 7 days, one month, and 3 months, defined by a decrease of at least 50% of visual analog scale (VAS) scores. RESULTS Technical success rate was 95.24%. Patients suffered from right unilateral occipital neuralgia in 3 cases, left unilateral occipital neuralgia in 2 cases, bilateral occipital neuralgia in 2 cases, migraine in one case, cervicogenic headache in one case, tension-type headache in 2 cases, and cluster headache in one case. Block test efficacy was found in 93.3% (14/15) cases. Clinical efficacy was found in 80% of cases at 7 days, in 66.7% of cases at one month and in 60% of cases at 3 months. No major complications were noted. LIMITATIONS Some of the limitations of our study include that it represents a single institution. The low number of infiltrations included in this study, for this guidance procedure, is another bias. CONCLUSIONS This ultrasound-guided infiltration technique appears to be feasible, safe, non-ionizing, and fast when targeting the greater occipital nerve in its intermediate portion. This imaging guidance modality should be used in routine clinical practice. KEY WORDS Greater occipital nerve, infiltration, ultrasound guidance, corticosteroids, occipital neuralgia, craniofacial pain syndrome.