Peripheral Nerve Injuries in the Cervicothoracic Region

There are many etiologies of peripheral nerve injuries in the cervicothoracic region. The injuries commonly involve the phrenic nerve, the suprascapular nerve, the dorsal scapular nerve, the long thoracic nerve, or the thoracodorsal nerve. The nerves arise from the cervical plexus and brachial plexus. Causes of injury vary and may include trauma, compression, nerve entrapment, stretch or traction from repetitive movement, infection, surgical injury, or metabolic causes. Clinical presentation depends upon the motor and sensory innervation of the affected nerves. Diagnosis is mostly clinical but may also be confirmed with imaging or electrodiagnostic studies. Depending on the specific injury, management may be either surgical or conservative (physical therapy and avoidance of precipitating movements).

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

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Anatomy

Nerve roots emerge from the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord at the C1 level and below.

Cervical plexus

C1 through C4 nerve roots close to the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord merge to form the cervical plexus.

Cutaneous branches of the cervical plexus innervate the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin, transmitting sensory information:

  • C2: The lesser occipital nerve innervates the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin on the posterolateral aspect of the head and neck.
  • C2, C3: The greater auricular nerve innervates the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin of the ear and the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin over the parotid glands.
  • C2, C3: The transverse cervical nerve innervates the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin on the anterior and lateral aspects of the neck.
  • C3, C4: The supraclavicular nerve innervates the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin of the shoulder and clavicle region.

Motor branches of the cervical plexus innervate muscles of the shoulders and neck:

  • C1, C3: The ansa cervicalis (superior and inferior roots) innervates the infrahyoid muscles (omohyoid, sternohyoid, and sternothyroid) of the neck.
  • C1, C5: The segmental and other muscular branches innervate the deep muscles (geniohyoid and thyrohyoid) of the neck and portions of the scalenes, levator scapulae, trapezius, and sternocleidomastoid muscles.
  • C3, C5: The phrenic nerve innervates the diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm.
Cervical plexus

Cervical plexus:
C1 through C4 nerve roots close to the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord merge to form the cervical plexus.

Image: “Cervical plexus” by Henry Vandyke Carter. License: Public Domain

Brachial plexus

C5 through T1 nerve roots merge to form the brachial plexus, which travels from the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord into the cervicoaxillary canal and the armpit. The nerves are divided into regions called trunks, divisions, cords, branches, and nerves.

  • Trunks: 
    • C5 and C6 roots merge to form the upper trunk.
    • The C7 root forms the middle trunk.
    • C8 and T1 roots merge to form the lower trunk.
  • Divisions: Each trunk divides into an anterior and posterior division, which creates 6 distinct divisions.
  • Cords are named with respect to the location of the axillary artery:
    • Anterior divisions of the upper and middle trunk form the lateral cord.
    • The anterior division of the lower trunk forms the medial cord.
    • Posterior divisions of all 3 trunks form the posterior cord.
  • Branches and nerves:
    • The long thoracic nerve arises from the roots of C5, C6, and C7.
    • The dorsal scapular nerve arises from the root of C5.
    • The suprascapular nerve arises from the upper trunk.
    • The lateral cord divides and gives rise to the musculocutaneous nerve and contributes to the median nerve.
    • The posterior cord branches and gives rise to the axillary nerve, the subscapular nerve, the thoracodorsal nerve, and the radial nerve.
    • The medial cord branches and contributes to the median nerve and then becomes the ulnar nerve. The medial cord also gives rise to the medial cutaneous nerves of the arm Arm The arm, or "upper arm" in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm and forearm Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term "forearm" is used in anatomy to distinguish this area from the arm, a term that is commonly used to describe the entire upper limb. The forearm consists of 2 long bones (the radius and the ulna), the interosseous membrane, and multiple arteries, nerves, and muscles. Forearm.
Brachial plexus

Schematic of the brachial plexus and the branches of the brachial plexus

Image by Lecturio.

Phrenic Nerve Injury

The phrenic nerve arises from anterior rami of C3, C4, and C5 nerve roots and provides motor innervation to the diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm:

Etiology of injury

  • Cardiac and thoracic surgery Thoracic Surgery Basic surgical intervention in the thoracic cavity has the primary goal of alleviating any malady that mechanically affects the function of the heart and lungs, which can be secondary to underlying pathologies or, most commonly, trauma. Interventions include tube thoracostomy, thoracentesis, and emergency thoracotomy. Thoracic Surgery
  • Blunt or penetrating trauma
  • Metabolic diseases (e.g., diabetes)
  • Infections (e.g., Lyme disease Lyme disease Lyme disease is a tick-borne infection caused by the gram-negative spirochete Borrelia burgdorferi. Lyme disease is transmitted by the black-legged Ixodes tick (known as a deer tick), which is only found in specific geographic regions. Patient presentation can vary depending on the stage of the disease and may include a characteristic erythema migrans rash. Lyme Disease, herpes zoster Herpes Zoster Varicella-zoster virus (VZV) is a linear, double-stranded DNA virus in the Herpesviridae family. Shingles (also known as herpes zoster) is more common in adults and occurs due to the reactivation of VZV. Varicella-Zoster Virus/Chickenpox)
  • Tumor invasion
  • Cervical spondylosis
  • Multiple sclerosis Multiple Sclerosis Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease that leads to demyelination of the nerves in the CNS. Young women are more predominantly affected by this most common demyelinating condition. Multiple Sclerosis
  • Myopathy
  • Immunologic diseases (e.g., Guillain-Barré syndrome Guillain-Barré syndrome Guillain-Barré syndrome (GBS), once thought to be a single disease process, is a family of immune-mediated polyneuropathies that occur after infections (e.g., with Campylobacter jejuni). Guillain-Barré Syndrome)

Clinical features

Clinical features vary and depend upon the extent of the injury. Clinical features depend on whether nerves are injured bilaterally or unilaterally:

  • General:
    • Shortness of breath
    • Recurrent pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia
    • Anxiety
    • Insomnia Insomnia Insomnia is a sleep disorder characterized by difficulty in the initiation, maintenance, and consolidation of sleep, leading to impairment of function. Patients may exhibit symptoms such as difficulty falling asleep, disrupted sleep, trouble going back to sleep, early awakenings, and feeling tired upon waking. Insomnia
    • Morning headache
    • Excessive daytime somnolence
    • Orthopnea
    • Fatigue
  • Unilateral diaphragmatic paralysis:
    • Asymptomatic at rest
    • Exertional dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
    • Often found as an incidental finding on chest radiograph
  • Bilateral diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm paralysis: severe shortness of breath

Physical examination

  • Decreased breath sounds on the affected side
  • Dullness on percussion of the affected side
  • Inward movement of the epigastrium during inspiration

Diagnosis

  • Imaging:
    • Upright inspiratory chest radiograph:
      • Unilateral: elevated hemidiaphragm
      • Bilateral: smooth elevation of hemidiaphragm with small lung volumes, deep and narrow costophrenic and costovertebral sulci
    • Fluoroscopy:
      • Unilateral: paradoxical elevation of the paralyzed hemidiaphragm on inspiration compared to the rapid descent of the normal hemidiaphragm
      • Bilateral: limited use
    • Diaphragmatic ultrasonography (diaphragmatic movement and thickness)
  • Pulmonary function tests and arterial blood gases
  • Diaphragmatic electromyography
  • Measurement of transdiaphragmatic pressure

Management

  • Unilateral diaphragmatic paralysis:
    • Most are asymptomatic and do not require treatment.
    • Surgical plication
    • Transient ventilatory support
  • Bilateral diaphragmatic paralysis:
    • Ventilatory support
    • Diaphragmatic pacing
    • Surgical nerve reconstruction and diaphragmatic pacing
    • Antiviral therapy (for viral etiology)

Suprascapular Nerve Injury

The suprascapular nerve arises from the upper trunk of the brachial plexus (C5, C6) and gives:

  • Motor innervation to the supraspinatus and infraspinatus muscles
  • Sensory innervation to the glenohumeral and acromioclavicular joints

Injury most commonly occurs at the suprascapular notch, the spinoglenoid notch, or the superior transverse scapular ligament.

Suprascapular and axillary nerves of right side

The path of the suprascapular nerve:
The suprascapular nerve is most commonly injured at the suprascapular notch, the spinoglenoid notch, or the superior transverse scapular ligament.

Image: “Suprascapular and axillary nerves of right side, seen from behind” by Henry Vandyke Carter. License: Public Domain

Etiology of injury

  • Nerve entrapment in the suprascapular or spinoglenoid notch (also known as suprascapular nerve entrapment syndrome)
  • Trauma
  • Stretch or traction from repetitive movement (often in athletes)
  • Compression by a mass:
    • Ganglion cyst
    • Bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones cyst
    • Tumor

Clinical features

  • Shoulder pain Shoulder Pain Acute shoulder injuries are a common reason for visits to primary care physicians and EDs. Common acute shoulder injuries include acromioclavicular joint injuries, clavicle fractures, glenohumeral dislocations, proximal humerus fractures, and rotator cuff tears. Acute Shoulder Pain (impingement at the suprascapular notch)
  • Painless weakness (impingement at the spinoglenoid notch)
  • Dysfunction of shoulder abduction (supraspinatus weakness)
  • Dysfunction of shoulder external rotation (infraspinatus weakness)
  • Muscle atrophy

Diagnosis

  • Clinical (based on clinical features of disease):
    • Classic finding: aching pain in the superior and posterior shoulder
    • Pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain may radiate to the arm Arm The arm, or "upper arm" in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm or neck.
    • Typically, symptoms worsen slowly.
  • Electrodiagnostic studies are the gold standard for diagnosis: evaluation of nerve latency, amplitude, fibrillation, and sharp waves
  • Imaging: 
    • Radiograph can show bony disease.
    • CT is useful for nerve impingement or abnormality.
    • MRI can identify soft tissue disease.

Management

  • Conservative management:
    • May help individuals with isolated neuropathy
    • Improvement or resolution may take 12 months.
    • Antiinflammatory medications
    • Physical therapy (to preserve the range of motion and strengthen shoulder/rotator cuff muscles)
    • The individual should avoid precipitating movements.
    • Ultrasound-guided injections
  • Surgical release (i.e., transverse scapular ligament)
  • Arthroscopic nerve decompression
  • Surgical excision (e.g., cysts, tumors)

Dorsal Scapular Nerve Injury

The dorsal scapular nerve arises from the anterior ramus of the C5 nerve root:

  • Innervates rhomboid major and minor muscles (retract, elevate, and stabilize the scapula)
  • Innervates the levator scapulae (elevates the scapula, inferiorly rotates the glenoid cavity)

Etiology and clinical features

Dorsal scapular nerve syndrome is caused by nerve compression:

  • Cause of injury: nerve entrapment due to hypertrophy of the middle scalene muscle
  • Clinical features vary, but the classic appearance is a “winged scapula”:
    • Winged scapula: The scapula is further from the midline than the noninjured side.
    • Limited range of motion (inability to pull the shoulder back)
    • Shoulder pain Shoulder Pain Acute shoulder injuries are a common reason for visits to primary care physicians and EDs. Common acute shoulder injuries include acromioclavicular joint injuries, clavicle fractures, glenohumeral dislocations, proximal humerus fractures, and rotator cuff tears. Acute Shoulder Pain
    • Muscle spasms
    • Midscapular dysesthesia
Scapula winging

Scapula winging:
A winged scapula can result from dorsal scapular nerve injury.

Image: “Right sided Winging of Scapula” by Dwaipayanc. License: CC BY-SA 3.0

Management

Conservative management is preferred. Surgery is reserved for individuals with severe injury refractory to nonoperative means:

  • Physical therapy and exercise
  • Antiinflammatory medications
  • Surgery:
    • Fascial graft
    • Muscle transfer

Long Thoracic Nerve Injury

The long thoracic nerve is a pure motor nerve, which travels inferiorly along the serratus anterior muscle:

  • Arises from C5, C6, and C7 nerve roots (C7 innervation is occasionally absent)
  • Innervates the serratus anterior muscle (responsible for pulling the scapula forward)

Etiology

  • Neuralgic amyotrophy
  • Surgery (e.g., breast cancer Breast cancer Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Breast Cancer surgery)
  • Trauma or compression (e.g., underarm injury from athletics)
  • Stretch or traction from repetitive activities (e.g., carrying a heavy weight for a prolonged period of time)

Clinical features

Clinical features are generally minimal. Classic findings and symptoms may be present in more severe cases:

  • Winged scapula: most prominent when the affected arm Arm The arm, or "upper arm" in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm is lifted forward
  • Demonstrated by the individual pressing against a wall with outstretched arms
  • Not specific to long thoracic nerve injury; also seen in:
    • Spinal accessory nerve injury
    • Dorsal scapular nerve injury
    • Cervical radiculopathy
    • Primary muscle diseases

Management

  • Conservative management (preferred):
    • The individual should avoid precipitating movements.
    • Physical therapy and exercise (maintain range of movement and strengthen muscles)
  • Surgery:
    • Muscle transfer
    • Fascial graft
    • Nerve transfer (using thoracodorsal or medial pectoral nerve)

Thoracodorsal Nerve Injury

Thoracodorsal nerve:

  • A pure motor nerve branching from the posterior cord
  • Fibers arise from C6, C7, and C8 roots.
  • Innervates the latissimus dorsi muscle:
    • The muscle is responsible for extension, adduction, transverse extension, and internal rotation of the shoulder joint.
    • If the latissimus dorsi is used for reconstruction during transplantation, the nerve supply is preserved.

Etiology

Thoracodorsal nerve injury can occur from surgical injury during axillary dissection for breast cancer Breast cancer Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Breast Cancer.

Clinical features

  • Mild weakness in extension, internal rotation, and adduction of the shoulder
  • The deficit is well compensated by the intact shoulder musculature.

Diagnosis

  • Clinical 
  • To test shoulder extension, internal rotation, and adduction, ask the individual to place the dorsum of the hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand on the opposite buttock.

Management

  • Braces or splints
  • Physiotherapy
  • Surgical decompression
Latissimus dorsi muscle

Latissimus dorsi muscle (part of the superficial or extrinsic posterior axioappendicular muscles)

Image by BioDigital, edited by Lecturio

References

  1. Reece C.L., Varacallo M., Susmarski A. (2020). Suprascapular Nerve Injury. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK559151/
  2. Rutkove S.B. (2019). Overview of upper extremity peripheral nerve syndromes. In Shefner J.M. et al. (Ed.), UpToDate. Retrieved August 27, 2021, from https://www.uptodate.com/contents/overview-of-upper-extremity-peripheral-nerve-syndromes
  3. Celli B.R. (2021). Causes and diagnosis of unilateral diaphragmatic paralysis and eventration in adults. In King T.E. et al. (Ed.), UpToDate. Retrieved August 27, 2021, from https://www.uptodate.com/contents/causes-and-diagnosis-of-unilateral-diaphragmatic-paralysis-and-eventration-in-adults
  4. Celli B.R. (2021). Causes and diagnosis of bilateral diaphragmatic paralysis. In King T.E. et al. (Ed.), UpToDate. Retrieved August 27, 2021, from https://www.uptodate.com/contents/causes-and-diagnosis-of-bilateral-diaphragmatic-paralysis
  5. Celli B.R. (2021). Treatment of diaphragmatic paralysis. In Shefner J.M. et al. (Ed.), UpToDate. Retrieved August 27, 2021, from https://www.uptodate.com/contents/treatment-of-diaphragmatic-paralysis
  6. Mandoorah S., Mead T. (2020). Phrenic Nerve Injury. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK482227/
  7. Watson L.J. (2021). Brachial plexus. Geeky Medics. https://geekymedics.com/brachial-plexus/
  8. Chu B., Bordoni B. (2020). Anatomy, Thorax, Thoracodorsal Nerves. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK539761/
  9. Bishop K.N., Varacallo M. (2021). Anatomy, Shoulder and Upper Limb, Dorsal Scapular Nerve. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK459343/

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