American Society for Peripheral Nerve

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Compression Topography of the Lesser Occipital Nerve: A Cadaver Study
Ziv Peled, MD1; Giorgio Pietramaggiori, MD2; Saja Scherer, MD2 1Peled Plastic Surgery, San Francisco, CA; 2Plastic Surgery Department, University Hospital of Lausanne, Switzerland, Lausanne, Switzerland

Introduction: Surgical treatment for chronic headaches has demonstrated impressive and consistent efficacy in a number of clinical studies. The occipital region is one primary target for this surgical approach, yet the majority of published studies on this particular topic focus on the greater occipital nerve. The lesser occipital nerve (LON) may also be an important surgical target, yet is often only described in passing and is usually resected.

Methods: The aim of the current study was to define the anatomy and compression topography of the lesser occipital nerve. Eight fresh frozen cadaver heads were dissected to identify the LON. The emergence of the LON was measured in relation to established surgical landmarks: the occipital protuberance (OP), the midline and the nuchal line. 15 LONs were identified in eight dissected heads. Three potential compression zones have been identified clinically based on the senior authorís (ZP) experience: 1) the zone of emergence of the LON from deep to the sternocleidomastoid (SCM) muscle, 2) the ascent of the LON along the posterior border of the SCM and 3) the point at which the LON crosses the nuchal line. All three zones were examined and measured in this study.

Results: The emergence of the LON from deep to the SCM occurred on average 7.8 cm caudal to the OP and 6.4 cm from the midline. The midpoint of ascent of the LON along the posterior SCM border occurred on average 5.5 cm caudal to the OP and 6.2 cm from the midline. At least one consistent branch point below the nuchal line was noted in all specimens. This first branch point occurred on average 3.8 cm caudal to the OP and 5.9 cm from the midline. The medial-most LON branch crossed the nuchal line an average of 5.4 cm lateral to the midline and the lateral-most LON branch crossed the nuchal line an average of 6.5 cm lateral to the midline.

Conclusions: The compression topography of the LON consists of three distinct compression zones. The findings of this cadaver study corroborate the clinical experience of the senior author and can help the surgeon identify the LON at its proximal compression point as it emerges from deep to the SCM. While the more distal compression topography and branching pattern can be quite variable, these results may aid the surgeon in safely dissecting and preserving the LON during surgical treatment of chronic headache patients.


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