Intramuscular Innervation of the Supraspinatus Muscle Assessed Using Sihler’s Staining: Potential Application in Myofascial Pain Syndrome

Abstract

Despite the positive effects of botulinum neurotoxin (BoNT) injection into the neural arborized area, there is no anatomical evidence in the literature regarding the neural arborization of the supraspinatus muscle. The present study aimed to define the intramuscular neural arborized pattern of the supraspinatus muscle using the modified Sihler’s staining method to facilitate the establishment of safe and effective injection sites in patients with myofascial pain in the supraspinatus muscle. Seventeen supraspinatus muscles from 15 embalmed cadavers were dissected. Precise suprascapular nerve entry locations were also observed. Intramuscular neural arborization was visualized by Sihler’s staining. The supraspinatus muscle was divided into four portions named A, B, C, and D. The nerve entry points were observed in 88.2% (15 of 17 cases) of section B and 76.5% (13 of 17 cases) of section C of the supraspinatus muscle, respectively. The concentration of intramuscular neural arborization was highest in section B of the supraspinatus muscle, which was the center of the supraspinatus muscle. When the clinician performs a trigger point and a BoNT injection into the supraspinatus muscle, injection within the medial 25–75% of the supraspinatus muscle will lead to optimal results when using small amounts of BoNT and prevent undesirable paralysis.

Distribution of the intramuscular innervation of the triceps brachii: Clinical importance in the treatment of spasticity with botulinum neurotoxin

“…Spasticity is a major cause of pain, resulting in poor hygiene and difficulties in performing activities of daily living (Lee et al, 2022a(Lee et al, , 2022bYi et al, 2019). The most common spastic pattern in the upper limbs is the elbow flexion with forearm pronation.…”

“…This may result in the formation of antibodies with lower effectiveness (Hsu et al, 2004;Kinnett, 2004;Lepage et al, 2005). To reduce these negative effects, a lesser amount of BoNT should be injected directly into the neural arborized areas (Lee et al, 2022a(Lee et al, , 2022bRha et al, 2016).…”

“…The Sihler procedure requires a series of steps to develop a real image of intramuscular neural distribution (Lee et al, 2022a, 2022b; Rha et al, 2016; Yi, Lee, Choi, Lee, Lee, & Kim, 2021; Yi, Lee, Lee, Seo, & Kim, 2021). After the staining procedures, the triceps brachii muscles were divided into 10 equal divisions, each representing a 10% increase in the total length.…”

Sihler's staining technique: How to and guidance for botulinum neurotoxin injection in human muscles

“…In this review, we will summarize the Sihler's staining technique and published articles describing the locations of botulinum neurotoxin injections (Lee et al, 2022a; Lee et al, 2022b).…”

Sonoanatomy and an ultrasound scanning protocol of the intramuscular innervation pattern of the infraspinatus muscle

“…Since BoNT inhibits the release of acetylcholine at the neuromuscular junction and myofascial trigger points are associated with motor endplates,7 BoNT should be injected close to the neural arborized area that is adjacent to the motor endplate or nerve ending 8. Many studies have focused on the anatomical location of the neuromuscular junctions of various muscles to establish possible clinical BoNT injection sites,9–11 and results have shown that injections targeting the neural arborized area (endplate-targeted injection), where most neuromuscular junctions are found, are superior to injections targeting the non-neural arborized area 12 13. However, it has been difficult to locate myofascial trigger points and design accurate injections for MPS in the IS, since the actual anatomic location of the neuronal arborization of IS has not been previously elucidated.…”