Long Thoracic Nerve

Snapshot

• A 47-year-old woman is undergoing an elective mastectomy with axillary node dissection after being diagnosed with breast cancer and having clinically positive axillary lymph nodes. On post-operative follow-up the patient’s major concern is pain and weakness of the right shoulder. She reports that her husband noticed asymmetry in her shoulder blades. On physical exam, there is winging of the scapula when she is pushing against the wall.

Introduction (Long Thoracic Nerve)

• Anatomy
  • arises from the 5th, 6th, and 7th cervical nerve roots that innervates the
    • serratus anterior muscle
  • the long thoracic nerve is a pure motor nerve 
• Clinical correlate
  • injury to the long thoracic nerve results in
    • winging of the scapula which can be demonstrated when
      • the patient presses against the wall which leads to
        • the affected scapula projecting out 
      • etiologies include
        • neuralgic amyotrophy
          • this is an inflammatory disorder affecting the brachial plexus
        • trauma to the nerve
          • examples include
            • a direct blow to the shoulder or the lateral chest wall (e.g., football)
            • surgical procedures such as
              • resection of the first rib
              • mastectomy with dissection of the axillary node
              • infraclavicular plexus anesthesia
        • stretch or traction of the nerve can occur with
• repetitive motion when doing sports or physical labor

Overview

The long thoracic nerve is the nerve responsible for innervating the serratus anterior muscle. To understand its anatomy, let’s break it down step by step:

1. Origin: The long thoracic nerve arises from the brachial plexus, which is a network of nerves formed by the anterior rami of the lower cervical spinal nerves (C5-C8) and the first thoracic spinal nerve (T1). Specifically, the long thoracic nerve originates from the anterior rami of the fifth, sixth, and seventh cervical nerves (C5-C7).
2. Course: After its origin, the long thoracic nerve descends along the side of the chest wall, running between the layers of the deep cervical fascia. It courses along the lateral aspect of the chest wall, passing deep to the axilla (armpit) and the pectoralis major muscle.
3. Innervation: It provides motor innervation to the serratus anterior muscle. This muscle originates from the upper eight or nine ribs and attaches to the medial border of the scapula. The motor signals carried by the long thoracic nerve control the contraction of the serratus anterior, allowing it to perform its functions of scapular stabilization, protraction (pulling the scapula forward), and upward rotation.
4. Relationship with other structures: Along its course, the long thoracic nerve is in proximity to several important structures. It runs close to the lateral border of the first rib, passes between the layers of the deep cervical fascia, and is located deep to the axilla. It also passes superficially to the thoracic wall muscles and deep to the axillary vein and artery.

Studies

1. Anatomy of the Long Thoracic Nerve:
   • “The Long Thoracic Nerve: Study of Anatomical Variations and Proposal of a Classification Scheme” (2019): This study examined the anatomical variations of the long thoracic nerve in cadaveric specimens and proposed a classification system based on the branching patterns of the nerve.
2. Long Thoracic Nerve Palsy:
   • “Scapular Dyskinesis: From Basic Science to Ultimate Treatment” (2014): This review article discusses the etiology, clinical presentation, and management of scapular dyskinesis.
   • “Long Thoracic Nerve Palsy: A Review of Anatomy, Causes, Evaluation, and Treatment” (2017): This comprehensive review provides an overview of the anatomy, etiology, clinical evaluation, and treatment options for long thoracic nerve palsy.
3. Treatment and Rehabilitation:
   • “Rehabilitation Strategies for Serratus Anterior Muscle Dysfunction: A Systematic Review” (2017): This systematic review evaluates various rehabilitation strategies, including exercise-based interventions, for serratus anterior muscle dysfunction, such as in cases of long thoracic nerve palsy.
   • “Nerve Transfer for Long Thoracic Nerve Palsy: A Systematic Review” (2020): This systematic review investigates the effectiveness of nerve transfer procedures as a treatment option for long thoracic palsy.
4. Nerve Monitoring and Surgery:
   • “Intraoperative Neurophysiological Monitoring in Long Thoracic Nerve Palsy: A Feasibility Study” (2021): This study explores the feasibility of using intraoperative neurophysiological monitoring techniques during surgical procedures to evaluate and protect.
   • “Outcome of Surgical Neurolysis for Long Thoracic Nerve Palsy in Patients with Multilevel Cervical Disc Disease” (2018): This study examines the outcomes of surgical neurolysis, a procedure aimed at decompressing the long thoracic nerve, in patients with long thoracic nerve palsy and multilevel cervical disc disease.

Treatment

The treatment of long thoracic nerve palsy aims to alleviate symptoms, restore function, and improve the stability of the scapula. The specific approach to treatment may vary depending on the severity of the condition, individual patient factors, and the underlying cause of the nerve palsy. Here are some common treatment options:

1. Conservative Management:
   • Activity modification: Avoiding activities that worsen symptoms or put excessive strain on the affected shoulder can help prevent further damage and promote healing.
   • Rest and immobilization: In some cases, wearing a sling or brace to limit movement and provide support to the affected shoulder may be recommended, especially in the acute phase of nerve injury.
   • Physical therapy: A structured physical therapy program is typically a key component of treatment. It aims to strengthen the surrounding muscles, improve scapular stability, restore proper movement patterns, and enhance functional abilities. Therapeutic exercises, manual therapy techniques, and neuromuscular retraining may be employed.
   • Pain management: Nonsteroidal anti-inflammatory drugs (NSAIDs) or other pain medications may be prescribed to manage pain and inflammation associated with long thoracic nerve palsy.
2. Surgical Interventions:
   • Nerve decompression: If the nerve is compressed by nearby structures, surgical decompression may be performed to relieve the pressure on the long thoracic nerve.
   • Nerve transfer: In some cases, nerve transfer procedures may be considered. This involves rerouting a healthy nerve to the serratus anterior muscle to restore function. Common donor nerves include branches of the accessory nerve or segments of the intercostal nerves.

It’s important to note that the choice of treatment depends on various factors, including the severity of the long thoracic nerve palsy, the patient’s overall health, and their individual goals and preferences. A healthcare professional, such as a neurologist, orthopedic specialist, or physiotherapist, can evaluate the specific condition and recommend the most appropriate treatment plan for the individual.

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