Determination of the Possible Innervation Zone and Intramuscular Nerve Distribution of the Neck Muscles with the Modified Sihler's Staining Technique
Project no. 21838 · Status: Kapanmış · 2020
Summary
Objective: We aimed to describe the optimal places for intramuscular applications like botulinum toxin used in the treatment of common diseases such as cervical dys-tonia by determining the innervation zone and intramuscular nerve distribution of the sternocleidomastoid (SCM) and splenius capitis (SC) muscles. We targeted to descri-be the nerve innervation zones of the muscles and the injection sites according to the bone landmarks that can be applied to the patient. Another objective is to describe relations of intramuscular nerve zones with adjacent vascular structures that may cau-se complications during injections. Material and methods: In our study, 28 neck muscles fixed with 10% formalin were used. Totally 14 right and left SCM of 7 cadavers, and 14 right and left SC of 7 ot-her cadavers were investigated. For each muscle, bone landmarks were chosen to represent the length of the muscle in accordance with the origin and insertion points. The tip of the mastoid process (PM) superiorly and the sternoclavicular joint inferi-orly were selected for SCM. The posterior edge of the mastoid process (PMa) superi-orly and the tip of the spinous process of T1 vertebrae inferiorly were selected for SC. The risky vascular structures for injection were determined and measured during dissection. Motor entry points (MGN) were determined and measured on the musc-les. The modified Sihler's staining technique (MST) was applied after the muscles were dissected and removed. At the end of the technique, the distribution of stained nerve fibers between muscle fibers that became transparent was examined. Intramus-cular nerve innervation zones were determined at 10% intervals. Innervation zones were defined according to other landmarks that determined on the neck for botuli-num toxin and other injections. Results: The lengths of SCM and SC were respectively 160.1 ± 1.17 mm and 116.6 ± 2.76 mm according to the selected landmarks. It was determined that SCM had 2 MGN in 14.3% cases and 1 MGN in 85.7% cases. The distance of accessory nerve MGN to the tip of the PM was 48 ± 0.61 mm. The SC had 1 to 3 MGNs. The SC had 1 MGN in 35.7% cases, 2 MGN in 35.7% cases and 3 MGN in 28.6% cases. The dis-tance of MGN’s of SC to PMa-the external occipital protuberance line ranged from 14 mm to 85.5 mm and the distance to the midline ranged from 4 mm to 55 mm. The MST was successfully applied in 28 muscles and intramuscular nerves could be tra-ced in all cases. The intramuscular innervation of the SCM was intense at the level of 40-70% of the muscle length in the anterior part and 50-70% in the posterior part of the muscle. On the other hand, intramuscular innervation of the SC was intense at the level of 10-30% of the muscle length in the medial part and 50-70% and 80-100% in the lateral part of the muscle. Conclusion: The MST has been successfully applied in the neck muscles. The inner-vation zones and intramuscular nerve distribution of the SCM and the SC muscles were determined. In cervical dystonia, the BT injection may give more effective re-sults if it’s applied to these muscles’ nerve innervation zones. It is important to know the MGNs of the muscles to prevent muscle paralysis in surgical interventions in the neck region.