Hip Adductor Intramuscular Nerve Distribution Pattern of Children: A Guide for BTX-A Treatment to Muscle Spasticity in Cerebral Palsy.

To investigate the intramuscular nerve distribution pattern in the hip adductors of children and to precisely locate the injection site for botulinum toxin type A (BTX-A) as a treatment for hip adductor spasticity in children with cerebral palsy. Modified Sihler's whole mount nerve staining technique was employed to observe the distribution of intramuscular nerves in hip adductors of children and to further locate zones where terminal nerves are concentrated. The terminal nerves of the adductor longus appeared in a longitudinal distribution band parallel to the line between the upper 1/3 point of the lateral boundary and the center of the medial boundary. In adductor brevis, the terminal nerves showed a sheet-like distribution with a nerve dense area located in the middle of the muscle belly that extends from the upper-inner region to the lower-outer region. Gracilis showed a dense area of terminal nerves in the middle of the muscle belly, closer to the posterior boundary. In adductor magnus, the dense area of terminal nerves showed a sheet-like distribution in the middle and lower region of the muscle belly. The dense area of terminal nerves in the pectineus was located in the middle of the muscle belly. This study is the first to systematically investigate the intramuscular nerve distribution pattern in the hip adductors. The results indicated that the best targets for BTX-A injection, when treating spasticity, are the dense regions of terminal nerves described above.

Intramuscular nerve distribution patterns of anterior forearm muscles in children: a guide for botulinum toxin injection.

Botulinum toxin (BoNT) can relieve muscle spasticity by blocking axon terminals acetylcholine release at the motor endplate (MEP) and is the safest and most effective agent for the treatment of muscle spasticity in children with cerebral palsy. In order to achieve maximum effect with minimum effective dose of BoNT, one needs to choose an injection site as near to the MEP zone as possible. This requires a detailed understanding about the nerve terminal distributions within the muscles targeted for BoNT injection. This study focuses on BoNT treatment in children with muscle spasms caused by cerebral palsy. Considering the differences between children and adults in anatomy, we used child cadavers and measured both the nerve entry points and nerve terminal sense zones in three deep muscles of the anterior forearm: flexor digitorum profundus (FDP), flexor pollicis longus (FPL), and pronator quadratus (PQ). We measured the nerve entry points by using the forearm midline as a reference and demonstrated intramuscular nerve terminal dense zones by using a modified Sihler's nerve staining technique. The locations of the nerve entry points and that of the nerve terminal dense zones in the muscles were compared. We found that all nerve entry points are away from the corresponding intramuscular nerve terminal dense zones. Simply selecting nerve entry points as the sites for BoNT injection may not be an optimal choice for best effects in blocking muscle spasm. We propose that the location of the nerve terminal dense zones in each individual muscle should be used as the optimal target sites for BoNT injection when treating muscle spasms in children with cerebral palsy.

Lidocaine Injection in the Intramuscular Innervation Zone Can Effectively Treat Chronic Neck Pain Caused by MTrPs in the Trapezius Muscle.

BACKGROUND: An increasing number of people suffer from neck pain due to life style and prolonged use of computers. Research has revealed that myofascial trigger points (MTrPs) and the intramuscular innervation zone (IZ) are involved in neck pain. MTrPs are induced mainly by IZ dysfunction of the affected skeletal muscle and the 2 do not overlap in location. The question is whether injection treatment in MTrPs or in the IZ is more effective to relieve MTrPs-associated pains. The precise location and body-surface map of the intramuscular IZ in the trapezius muscle and a clinical injection study in the IZ may provide a useful answer to the question. OBJECTIVES: This study aimed to investigate the efficacy of lidocaine injection in the intramuscular IZ for the treatment of chronic neck pain caused by MTrPs in the trapezius muscle. STUDY DESIGN: Prospective observational study, approved by the local research ethics. SETTING: University hospital, departments of Anesthesiology and Anatomy. METHODS: First, for the determination of IZ distribution and body-surface mapping, a modified intramuscular Sihler's neural staining technique was applied to elucidate nerve distribution patterns of the trapezius muscle. Then, 120 patients with myofascial pain syndrome (MPS) of the trapezius muscle were randomly divided into 5 groups for analysis. Group 1 (n = 24) received injections of saline (0.9% NaCl) at the MTrPs. Group 2 (n = 24) received injections of 0.5% lidocaine at the MTrPs. Group 3 (n = 24) received injections of saline (0.9% NaCl) at the mid-upper trapezius (Point E). Group 4 (n = 24) received injections of 0.5% lidocaine at Point E. Group 5 (n = 24) received a combined injection of 0.5% lidocaine treatment at both Point E and the lower trapezius (Point F). The injection dose was 4 mL at each injection site. All patients received injections once a week for 4 weeks. The visual analogue scale (VAS) and the frequency of painful days per month (FPD) were obtained before treatment and at 2, 4, and 6 months after treatment. RESULTS: The intramuscular terminal nerve branches presented a "dendritic" distribution in the trapezius muscle and were connected with each other to form an S-shaped IZ belt in the middle of the muscle belly. Compared with the MTrP injection group, lidocaine-injection therapy in the IZ significantly reduced the degree and frequency of neck pain in patients at 6 months after treatment, especially the combined lidocaine-injection therapy in the IZ of both the mid-upper trapezius and the lower trapezius are more effective (all P < 0.05). CONCLUSIONS: This study confirms that lidocaine-injection therapy in the IZ significantly reduces the degree and frequency of neck pain in patients at 6 months after treatment. The combined lidocaine-injection therapy in the IZ of both the mid-upper trapezius and the lower trapezius is more effective. In addition, this study establishes a clear distribution map of intramuscular nerves that will be conducive to the future use of chemical blockers and electrical stimulation in the nervous system in treating MPS of the trapezius muscle. LIMITATIONS: The small number of patients and the short duration of follow-up.

Absence of musculocutaneous nerve associated with variations of distribution patterns of the median nerve / Ausencia del nervio musculocutáneo asociada con variaciones de los patrones de distribución del nervio mediano

Variations in the brachial plexus and the distribution patterns of its branches are not uncommon. A communicating branch, which is the most frequent variation, often arises from musculocutaneous nerve to median nerve. However, the branches arising from lateral cord of the brachial plexus and median nerve instead of musculocutaneous nerve are very rare. Detailed description of the abnormalities is important for surgical procedures. Our case study reports the musculocutaneous nerve was absent, a branch from the medial cord innervated the coracobrachialis muscle and two branches from the median nerve innervated the biceps and brachialis muscles, respectively. Moreover, the median nerve gave off the lateral antebrachial cutaneous nerve. This report provides evidence of such possible anatomical variations to surgeons, anesthetists and neurologists during clinical practice.

Las variaciones en el plexo braquial y los patrones de distribución de sus ramos no son infrecuentes. Un ramo comunicante, que es la variante más frecuente, a menudo surge desde el nervio musculocutáneo al nervio mediano. Sin embargo, los ramos que surgen del fascículo lateral del plexo braquial y nervio mediano en vez de nervio musculocutáneo son muy raros. La descripción detallada de las anomalías es importante para procedimientos quirúrgicos. En nuestro caso el nervio musculocutáneo estaba ausente, un ramo del fascículo medial inervó el músculo coracobraquial y dos ramos del nervio mediano inervaron los músculos bíceps y braquial, respectivamente. Por otra parte, el nervio mediano originó al nervio cutáneo antebraquial lateral. Este informe proporciona evidencia de algunas variaciones anatómicas útiles para cirujanos, anestesistas y neurólogos durante la práctica clínica.