Ultrasound‐Guided Injection of the Sternocleidomastoid Muscle: A Cadaveric Study with Implications for Chemodenervation

Abstract

Background Ultrasound guidance may improve the accuracy of botulinum toxin injection, but studies of its potential for cervical dystonia treatment are lacking. Objective To determine the accuracy of ultrasound‐guided injection in the sternocleidomastoid muscle (SCM). Design Observational study. Setting Tertiary care university hospital. Participants Eighteen embalmed cadavers. Interventions In total, 36 SCMs from 18 embalmed cadavers were examined. One physician performed ultrasound scans to divide each SCM into quarters and evaluated its cross‐sectional area (CSA) and thickness at each of three meeting points between adjacent quarters. Under ultrasound guidance, another experienced physician injected methylene blue solution at one of the three points, using the in‐plane technique (12 specimens per point; right SCM 3 mL, left SCM 5 mL). One anatomist dissected all cadavers and measured the distance of dye dispersion along the longitudinal axis of each muscle. Dispersion ratio was calculated as longitudinal dye dispersion divided by SCM length. Main Outcome Measures SCM thickness and CSA; dye dispersion patterns (dispersion distance and dispersion ratio). Results SCM thickness and CSA were greatest at the middle injection point (mean ± SD of 6.6 ± 2.0 mm and 1.4 ± 0.6 cm2, respectively). All injections were successful, except in one case where the SCM was thin and the dye reached the omohyoid muscle. Mean longitudinal dye dispersion and dispersion ratio were significantly greater when the volume was 5 mL. There were no statistically significant differences in dispersion patterns among the three injection points. Conclusions Ultrasound‐guided intramuscular injection can be performed with good accuracy in the SCM, as ultrasound can be used to evaluate SCM thickness and CSA. Higher volumes of injection solution appear to diffuse better, but further clinical studies are required to determine optimal injection volume.

The Emerging Era of Interventional Imaging in Rheumatology: An Overview During the Coronavirus Disease-2019 (COVID-19) Pandemic

“… 18 In addition, imaging also helps in sorting out the primary pathogenesis pathways that may lead to the chronicity of dactylitis in PsA patients. 19 DACTylitis glObal Sonographic (DACTOS) score is a consistent measure to understand the US characteristics of dactylitis and supports clinical diagnosis and management in PsA patients with dactylitis. 20 …”

The Role of Ultrasound for the Personalized Botulinum Toxin Treatment of Cervical Dystonia

“…This safety feature hands US guidance an undisputable advantage over other guiding techniques, such as the EMG, and, of course, non-guidance. Indeed, only the use of US has made it possible to research the accuracy of injections, which for US guided injections in CD, was estimated to be between 81-100% [17][18][19]. Furthermore, it is also proposed that as long as low volume injections are performed at a slow pace (to avoid backflow) and into the region with greatest width, the toxin would remain localized to the target muscle [18].…”

“…Indeed, only the use of US has made it possible to research the accuracy of injections, which for US guided injections in CD, was estimated to be between 81-100% [17][18][19]. Furthermore, it is also proposed that as long as low volume injections are performed at a slow pace (to avoid backflow) and into the region with greatest width, the toxin would remain localized to the target muscle [18]. It is therefore conceivable that given its high accuracy, US would be associated with less spread of toxin to the surrounding structures and in turn with fewer adverse events.…”

Architecture of head and neck soft tissues and associated entheses: An exploration of sexual dimorphism in, and population differences between, New Zealand and Thai individuals

“…Anatomical parameters can be influenced by factors such as sex, population and age (Alsalaheen et al, 2019; Frontera et al, 2000; Kim et al, 2021). Sexual dimorphism (Williams & Carroll, 2009) is evident in some cervical muscles, with males generally exhibiting larger muscle sizes than females (Alsalaheen et al, 2019; Keidan et al, 2021; Kennedy et al, 2017; Mayoux‐Benhamou et al, 1995; Rankin et al, 2005; Valera‐Calero et al, 2020).…”

“…Understanding population differences within anatomical data is also important to ensure that published information is applicable to diverse populations around the world. Interestingly, population variation is largely understudied in anatomy (Kim et al, 2021), despite its strong representation in the anthropological literature (Bidmos & Asala, 2004; de Paiva & Segre, 2003; Franklin et al, 2006; Orish et al, 2014; Suazo et al, 2009; Tallman, 2019; Walker, 2008). Anatomical studies on a range of populations are common in some areas, such as studies of anatomical variation in the sternocleidomastoid (Anıl et al, 2017; Cherian & Nayak, 2008; de Amorim et al, 2010; Dupont et al, 2018; Fazliogullari et al, 2010; Ferreira‐Arquez, 2018; Heo et al, 2020; Kim et al, 2015; Natsis et al, 2009; Oh et al, 2019; Raikos et al, 2012; Saha et al, 2014; Sirasanagandla et al, 2012).…”