Anatomy of the greater occipital nerve block in infants

Background: Pain relief for posterior fossa craniotomies as well as occipital neuralgia, are indications for the use of the greater occipital nerve block in children. The greater occipital nerve originates from the C2 spinal nerve and is accompanied by the occipital artery as it supplies the posterior scalp.

Aims: The aim of this study was to develop a unique, yet simple technique for blocking the greater occipital nerve in children through the evaluation of the anatomy of this nerve and the accompanying occipital artery in the occipital region.

Methods: The greater occipital nerve and occipital artery were dissected and exposed in six formalin-fixed cadavers (five infants [average age of 51.4 days] and one 2-year-old) from the Department of Anatomy, University of Pretoria. Measurements between the nerve and selected bony landmarks were obtained. The relationship between the greater occipital nerve and the occipital artery at the trapezius muscle hiatus was also evaluated.

Results: The greater occipital nerve is on average 22.6 ± 5.6 mm from the external occipital protuberance in infants. The average width of the medial three fingers measured at the proximal interphalangeal joint, for each respective cadaver is 20.4 ± 4.0 mm, with a strong correlation coefficient of 0.97 between the aforementioned distances. In 83.3% of the specimens, the occipital artery lies lateral to the greater occipital nerve at the trapezius muscle hiatus.

Conclusion: In infants, the greater occipital nerve can be blocked approximately 23 mm from the external occipital protuberance, medial to the occipital artery. This distance is equal to the width of the medial three fingers at the proximal interphalangeal joint of the patient.