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Cervical dermatome map. Cervical Spinal Nerves: Anatomy, Functions, and Clinical Significance

by alexxlab

How do cervical spinal nerves innervate the body. What are the key functions of each cervical nerve root. How can understanding cervical dermatomes aid in diagnosis and treatment.

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Anatomy of Cervical Spinal Nerves

The cervical spine contains eight pairs of spinal nerves, labeled C1 to C8. These nerves play a crucial role in transmitting sensory and motor information between the brain and various parts of the body. Each cervical spinal nerve emerges from the spinal cord through small openings called intervertebral foramina, located between adjacent vertebrae.

Nerve Root Structure

Each cervical spinal nerve is formed by the merger of two distinct nerve roots:

  • Ventral root: Located anteriorly, it carries motor signals from the brain to the muscles controlled by that specific nerve root (myotome).
  • Dorsal root: Positioned posteriorly, it transmits sensory information from the skin area innervated by that nerve root (dermatome) back to the brain.

These roots combine in the intervertebral foramen to form the spinal nerve, which then branches out to innervate specific regions of the body.

Functions of Cervical Spinal Nerves

Each cervical spinal nerve has unique functions in controlling movement and sensation in different parts of the body. Understanding these functions is essential for diagnosing and treating various neurological conditions.

C1, C2, and C3 Nerve Functions

The upper cervical nerves primarily control the head and neck region:

  • C1: Responsible for head rotation and flexion.
  • C2: Innervates the upper part of the head and provides sensation to the scalp.
  • C3: Controls neck flexion and provides sensation to the side of the face and back of the head.

C4 Nerve Functions

C4 plays a vital role in shoulder movement and respiration:

  • Facilitates upward shoulder movements.
  • Contributes to diaphragm function, along with C3 and C5, aiding in breathing.
  • Provides sensation to the lower neck and upper chest area.

C5-C8 Nerve Functions

The lower cervical nerves are crucial for upper limb function:

  • C5: Controls deltoid and biceps muscles, responsible for shoulder abduction and elbow flexion.
  • C6: Innervates wrist extensors and contributes to forearm pronation.
  • C7: Controls triceps and wrist flexors, essential for elbow extension and grip strength.
  • C8: Innervates hand intrinsic muscles, crucial for fine motor skills.

Cervical Dermatomes and Their Clinical Significance

A dermatome is a specific area of skin innervated by a single spinal nerve. Cervical dermatomes are essential in clinical practice for localizing nerve root compression or injury.

Mapping Cervical Dermatomes

The cervical dermatome map provides a visual representation of skin areas innervated by each cervical nerve:

  • C2: Posterior scalp and upper neck
  • C3: Lower neck and supraclavicular area
  • C4: Upper chest and shoulder region
  • C5: Lateral upper arm
  • C6: Lateral forearm and thumb
  • C7: Middle finger
  • C8: Medial forearm and little finger

Understanding these dermatome patterns helps clinicians identify the specific nerve root involved in various neurological conditions.

Clinical Applications of Cervical Nerve Knowledge

Comprehending cervical spinal nerve anatomy and function is crucial for diagnosing and treating various neurological and musculoskeletal conditions.

Diagnostic Applications

Cervical nerve knowledge aids in diagnosing conditions such as:

  • Cervical radiculopathy
  • Brachial plexus injuries
  • Cervical spondylosis
  • Thoracic outlet syndrome

By correlating symptoms with specific dermatomes and myotomes, clinicians can accurately pinpoint the affected nerve root.

Treatment Implications

Understanding cervical nerve anatomy guides treatment approaches, including:

  • Targeted physical therapy exercises
  • Precise medication administration
  • Surgical planning for nerve decompression
  • Rehabilitation strategies for nerve injuries

Cervical Spinal Cord Anatomy and Its Relationship to Spinal Nerves

The cervical spinal cord is an integral part of the central nervous system, serving as a conduit for information between the brain and the rest of the body. Its relationship with cervical spinal nerves is crucial for understanding various neurological conditions.

Spinal Cord Segments

The cervical spinal cord is divided into eight segments, corresponding to the eight cervical nerve pairs. Each segment contains gray matter (nerve cell bodies) and white matter (nerve fibers).

Spinal Tracts

The white matter of the spinal cord contains various tracts that carry specific types of information:

  • Ascending tracts: Carry sensory information to the brain
  • Descending tracts: Transmit motor commands from the brain

Damage to these tracts can result in specific patterns of sensory or motor deficits, depending on the location and extent of the injury.

Common Cervical Spine Disorders and Their Neurological Implications

Several disorders can affect the cervical spine and its associated nerves, leading to various neurological symptoms.

Cervical Radiculopathy

Cervical radiculopathy occurs when a nerve root is compressed or irritated, often due to a herniated disc or bone spur. Symptoms typically include:

  • Radiating pain along the affected nerve’s path
  • Numbness or tingling in the corresponding dermatome
  • Weakness in muscles innervated by the affected nerve

Cervical Myelopathy

Cervical myelopathy results from compression of the spinal cord itself, often due to degenerative changes or trauma. Symptoms may include:

  • Gait disturbances
  • Fine motor skill impairment
  • Sensory changes below the level of compression
  • Bowel and bladder dysfunction in severe cases

Brachial Plexus Injuries

The brachial plexus is a network of nerves formed by cervical and upper thoracic nerve roots. Injuries to this plexus can result in various upper limb dysfunctions, depending on the specific nerves affected.

Advanced Diagnostic Techniques for Cervical Nerve Disorders

Modern medical technology offers various advanced diagnostic tools for assessing cervical nerve function and identifying pathologies.

Electrodiagnostic Studies

Electrodiagnostic studies provide valuable information about nerve function:

  • Electromyography (EMG): Assesses muscle electrical activity and can detect denervation.
  • Nerve Conduction Studies (NCS): Measure the speed and strength of nerve signals.

Imaging Techniques

Advanced imaging modalities offer detailed views of cervical spine structures:

  • Magnetic Resonance Imaging (MRI): Provides excellent soft tissue contrast, ideal for visualizing nerve roots and spinal cord.
  • Computed Tomography (CT): Offers detailed bony anatomy, useful for assessing foraminal stenosis.
  • Myelography: Enhances visualization of the spinal cord and nerve roots when combined with CT or MRI.

Therapeutic Approaches for Cervical Nerve Disorders

Treatment of cervical nerve disorders often involves a multidisciplinary approach, tailored to the specific condition and its severity.

Conservative Management

Non-surgical treatments are often the first line of therapy and may include:

  • Physical therapy: To improve strength, flexibility, and posture
  • Medications: Such as anti-inflammatories or nerve pain modulators
  • Cervical traction: To relieve pressure on nerve roots
  • Activity modification: To avoid aggravating movements

Interventional Procedures

When conservative measures are insufficient, interventional procedures may be considered:

  • Epidural steroid injections: To reduce inflammation around compressed nerves
  • Radiofrequency ablation: For long-term pain relief in select cases
  • Spinal cord stimulation: For chronic neuropathic pain

Surgical Interventions

Surgery may be necessary in cases of severe or progressive neurological deficits. Common procedures include:

  • Anterior cervical discectomy and fusion (ACDF)
  • Cervical artificial disc replacement
  • Posterior cervical laminectomy or laminoplasty

The choice of surgical approach depends on the specific pathology, patient factors, and surgeon expertise.

Future Directions in Cervical Nerve Research and Treatment

The field of cervical spine and nerve research is continually evolving, with several promising areas of investigation.

Regenerative Medicine

Stem cell therapy and tissue engineering hold potential for repairing damaged nerves and spinal cord tissue. Current research focuses on:

  • Promoting nerve regeneration after injury
  • Enhancing spinal cord repair in cases of trauma or degenerative conditions
  • Developing bioengineered scaffolds to support nerve growth

Advanced Imaging and Diagnostic Tools

Emerging technologies aim to improve the accuracy and efficiency of cervical nerve diagnostics:

  • High-resolution MRI techniques for better visualization of small nerve structures
  • Functional MRI to assess real-time nerve activity
  • Artificial intelligence algorithms for automated image analysis and diagnosis

Minimally Invasive Surgical Techniques

Ongoing development of minimally invasive procedures aims to reduce surgical trauma and improve outcomes:

  • Endoscopic approaches for nerve decompression
  • Robot-assisted surgery for increased precision
  • 3D-printed implants customized to individual patient anatomy

As research progresses, these advancements promise to enhance our understanding of cervical nerve anatomy and function, leading to more effective diagnostic and treatment strategies for patients with cervical spine disorders.

Cervical Spinal Nerves | Spine-health

Spinal nerves branch off from the spinal cord to innervate the rest of the body. These complex networks of nerves enable the brain to receive sensory inputs from the skin and to send motor controls for muscle movements. In the cervical spine, there are eight pairs of spinal nerves labeled C1 to C8, which innervate the neck, shoulder, arm, hand, and more.

Learn how 8 pairs of spinal nerves in the neck play an important role in sending messages to and from the spinal cord. Watch Now

Nerve Root and Spinal Nerve Anatomy

Each level of the cervical spine has four nerve roots—two on each side—that branch off from the spinal cord. The two types of nerve roots on each side include:

  • Ventral root (located in front) that carries motor signals from the brain to that nerve root’s myotome, which is the group of muscles that it controls
  • Dorsal root (located in back) that carries sensory signals back to the brain from that nerve root’s dermatome, which innervates the specific region of skin that it covers

Watch Cervical Spinal Cord Anatomy Animation

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The ventral root and dorsal root branch off separately from the spinal cord then merge together in the intervertebral foramen, a small bony opening between the two adjacent vertebrae. When the ventral and dorsal roots merge, the combined nerve is called the spinal nerve. From there, the spinal nerve branches into a network of nerves that innervate its dermatome (for sensations) and myotome (for motor controls).

See Spinal Cord and Spinal Nerve Roots

When discussing symptoms with a patient, it is common for doctors and other medical experts to simplify the terminology by referring to a single nerve root rather than two, or by using the terms for nerve root and spinal nerve interchangeably.

In This Article:

  • Cervical Spine Anatomy

  • Cervical Vertebrae

  • Neck Muscles and Other Soft Tissues

  • Cervical Discs

  • Cervical Spinal Nerves

  • Spinal Cord Anatomy in the Neck

  • Cervical Spine Anatomy Video

  • Cervical Vertebrae Anatomy Animation

  • Cervical Muscle Anatomy Animation

  • Cervical Nerve Anatomy Animation

  • Cervical Spinal Cord Anatomy Animation

Cervical Nerve Functions

A dermatome is the area of sensory nerves near the skin that are supplied by a specific spinal nerve root. For example, the C5 dermatome is supplied by the C5 nerve root.

Cervical spinal nerves, also called cervical nerves, provide functional control and sensation to different parts of the body based on the spinal level where they branch out from the spinal cord. While innervation can vary from person to person, some common patterns include:

  • C1, C2, and C3 (the first three cervical nerves) help control the head and neck, including movements forward, backward, and to the sides.

    1
    Magee DJ. Cervical Spine. In: Magee DJ, ed. Orthopedic Physical Assessment. 5th ed. St. Louis, MO. Saunders Elsevier; 2008: 130-202.
    The C2 dermatome handles sensation for the upper part of the head, and the C3 dermatome covers the side of the face and back of the head.

    2
    Felten DL, O’Banion MK, Maida MS. Peripheral Nervous System. In: Netter’s Atlas of Neuroscience. 3rd ed. Elsevier; 2016:153-231. doi:10.1016/b978-0-323-26511-9. 00009-6
    (C1 does not have a dermatome.)

    See The C1-C2 Vertebrae and Spinal Segment

  • C4 helps control upward shoulder movements.

    1
    Magee DJ. Cervical Spine. In: Magee DJ, ed. Orthopedic Physical Assessment. 5th ed. St. Louis, MO. Saunders Elsevier; 2008: 130-202.
    C4 (along with C3 and C5) also helps power the diaphragm—the sheet of muscle that stretches to the bottom of the rib cage for breathing.

    1
    Magee DJ. Cervical Spine. In: Magee DJ, ed. Orthopedic Physical Assessment. 5th ed. St. Louis, MO. Saunders Elsevier; 2008: 130-202.
    The C4 dermatome covers parts of the neck, shoulders, and upper part of arms.

    2
    Felten DL, O’Banion MK, Maida MS. Peripheral Nervous System. In: Netter’s Atlas of Neuroscience. 3rd ed. Elsevier; 2016:153-231. doi:10.1016/b978-0-323-26511-9.00009-6

  • C5 helps control the deltoids (which form the rounded contours of the shoulders) and the biceps (which allow bending of the elbow and rotation of the forearm).

    1
    Magee DJ. Cervical Spine. In: Magee DJ, ed. Orthopedic Physical Assessment. 5th ed. St. Louis, MO. Saunders Elsevier; 2008: 130-202.
    The C5 dermatome covers the outer part of the upper arm down to about the elbow.

    2
    Felten DL, O’Banion MK, Maida MS. Peripheral Nervous System. In: Netter’s Atlas of Neuroscience. 3rd ed. Elsevier; 2016:153-231. doi:10.1016/b978-0-323-26511-9.00009-6

    See All About the C2-C5 Spinal Motion Segments

  • C6 helps control the wrist extensors (muscles that control wrist extension) and also provides some innervation to the biceps.

    1
    Magee DJ. Cervical Spine. In: Magee DJ, ed. Orthopedic Physical Assessment. 5th ed. St. Louis, MO. Saunders Elsevier; 2008: 130-202.
    ,
    3
    Childress MA, Becker BA. Nonoperative management of cervical radiculopathy. Am Fam Physician. 2016; 93(9):746-54.
    The C6 dermatome covers the thumb side of the hand and forearm.

    2
    Felten DL, O’Banion MK, Maida MS. Peripheral Nervous System. In: Netter’s Atlas of Neuroscience. 3rd ed. Elsevier; 2016:153-231. doi:10.1016/b978-0-323-26511-9.00009-6

    See All About the C5-C6 Spinal Motion Segment

  • C7 helps control the triceps (the large muscle on the back of the arm that straightens the elbow) and wrist extensor muscles.

    1
    Magee DJ. Cervical Spine. In: Magee DJ, ed. Orthopedic Physical Assessment. 5th ed. St. Louis, MO. Saunders Elsevier; 2008: 130-202.
    ,
    3
    Childress MA, Becker BA. Nonoperative management of cervical radiculopathy. Am Fam Physician. 2016; 93(9):746-54.
    The C7 dermatome goes down the back of the arm and into the middle finger.

    2
    Felten DL, O’Banion MK, Maida MS. Peripheral Nervous System. In: Netter’s Atlas of Neuroscience. 3rd ed. Elsevier; 2016:153-231. doi:10.1016/b978-0-323-26511-9.00009-6

    See All About the C6-C7 Spinal Motion Segment

  • C8 helps control the hands, such as finger flexion (handgrip).

    1
    Magee DJ. Cervical Spine. In: Magee DJ, ed. Orthopedic Physical Assessment. 5th ed. St. Louis, MO. Saunders Elsevier; 2008: 130-202.
    ,
    3
    Childress MA, Becker BA. Nonoperative management of cervical radiculopathy. Am Fam Physician. 2016; 93(9):746-54.
    The C8 dermatome covers the pinky side of the hand and forearm.

    2
    Felten DL, O’Banion MK, Maida MS. Peripheral Nervous System. In: Netter’s Atlas of Neuroscience. 3rd ed. Elsevier; 2016:153-231. doi:10.1016/b978-0-323-26511-9.00009-6

    See All About the C7-T1 Spinal Segment (Cervicothoracic Junction)

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If a cervical nerve becomes irritated or compressed, it may cause pain and/or dysfunction that correlates to its dermatome for sensations and/or myotome for motor control.

See Spinal Cord Compression and Dysfunction from Cervical Stenosis

Dr. Paul Slosar is an orthopedic surgeon and President of SpineCare Medical Group, a practice near San Francisco. He specializes in the cervical spine and has been a practicing spine surgeon for more than 25 years. Dr. Slosar is actively involved in spine research. He frequently lectures around the country and teaches seminars to fellow spine surgeons.

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Pulsenotes | Radiculopathies

Overview

Radiculopathy refers to symptoms or impairments related to the involvement of a spinal nerve root.


The spinal nerve roots serve as the main communication between the central nervous system (i.e. the spinal cord) and the peripheral nerves. When a spinal nerve root is affected, it is known as radiculopathy.


Radiculopathies may be single or multiple. When multiple nerve roots are affected it is known as polyradiculopathy. The symptoms of radiculopathy are usually characteristic because each root supplies a specific area of cutaneous tissue, known as the dermatome, and a functional group of muscles, known as a myotome. Therefore, patients typically present with radicular pain and/or sensory changes in the distribution of the dermatome with or without impairment of muscle function within the myotome.


Radiculopathies can be categorised by the type of nerve roots affected within the spine:


  • Cervical radiculopathies (C1-C8)

  • Thoracic radiculopathies (T1-T12)

  • Lumbosacral radiculopathies (L1-S3): by far the most common

Dermatomes and myotomes

Each spinal nerve root carries out important sensory/motor functions along a specific distribution.


The spinal nerve roots serve as the main communication between the central nervous system (i.e. the spinal cord) and the peripheral nerves. The spinal cord ends at the L1/L2 vertebrae and is divided into four main regions termed cervical, thoracic, lumbar, and sacral. These regions are further divided into 31 spinal cord segments. Arising from the 31 spinal cord segments are the paired ventral and dorsal spinal nerve roots, which join to form the 31 paired spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal).


Damage or impingement of a spinal nerve or root is known as radiculopathy. Each spinal nerve root carries out important sensory/motor functions along a specific distribution. These are known as myotomes and dermatomes:


  • Myotome: a collection of muscles innervated by a single spinal nerve root

  • Dermatome: an area of skin supplied by a single spinal nerve root

Dermatomes


A dermatome simply refers to an area of skin supplied by sensory nerves that are derived from a single spinal nerve. They are essentially a cutaneous map of spinal nerve innervation that is broadly similar across individuals. Sensory symptoms within a particular dermatome help localise the suspected radiculopathy.


The dermatomes are best visualised through an image of the human body.



Dermatome map in posterior and anterior view (C2-S4/5)


Labels refer to cutaneous sensory branches of peripheral nerves


Myotomes


A myotome simply refers to a group of muscles supplied by a single spinal nerve. There are several important myotomes to remember of the upper and lower limb, which are listed below:


  • C4: shoulder elevation

  • C5: shoulder abduction

  • C6: elbow flexion

  • C7: elbow extension

  • C8: thumb extension

  • T1: finger adduction

  • L1/L2: hip flexion

  • L3: knee extension

  • L4: ankle dorsiflexion

  • L5: great toe extension

  • S1: ankle plantar flexion

NOTE: this is an oversimplification of the myotomes and nerve roots may have overlapping functions (e. g. L2 assists in hip flexion, knee extension, and hip adduction).

Aetiology and pathophysiology

Degenerative spinal disease is commonly implicated in radiculopathies.


Degenerative changes in the spine are commonly the cause of impingement of the spinal nerve roots leading to clinical features consistent with radiculopathy. Changes to the intervertebral discs or zygapophyseal (facet) joints are the most likely structures involved.


Importantly, degenerative changes in the spine known as ‘spondylosis’ are common as people age. These may cause non-specific low back pain. This does not mean a patient has a radiculopathy or ‘sciatica’. When there are degenerative spondylotic changes affecting the nerve root(s) this is considered a radiculopathy and characterised by radicular pain that is often referred to as ‘sciatica’ (discussed more below).


There are two broad causes of radiculopathies:


  • Skeletal: most commonly degenerative spondylotic changes in the intervertebral discs and facet joints

  • Non-skeletal: a variety of causes including infection, vasculitis, inflammation, and neoplasia

Skeletal


The spine is formed by 33 vertebrae that are joined together by intervertebral joints. These include two major areas:


  • Joints at the vertebral bodies: between each vertebral body is an intervertebral disc composed of a central nucleus pulposus and surrounding annulus fibrosus

  • Joints at the arches: between superior and inferior articular processes of the vertebrae are facet joints. These are a type of synovial joint that provide stability and allow movement

The spine has several other joints depending on the location (e.g. Craniovertebral) and several important ligamentous structures to provided stability.


Damage to the facet joints (commonly due to arthritis) can lead to hypertrophy and the formation of small boney outgrowths known as osteophytes. These can lead to impingement of the spinal roots and subsequent radiculopathy. Alternatively, disruption of the facet joint by spondylosis can lead to misalignment of the spine and instability. If the misalignment affects the spinal nerves roots it will lead to radiculopathy and if it affects the spinal cord it will lead to myelopathy.


Damage to the intervertebral discs can lead to disc herniation and impingement of the spinal cord or spinal nerve roots. Herniation refers to the rupture of disc material (i.e. nucleus pulposus) beyond the annulus fibrosus. In fact, it is suggested that age-related change in the nucleus pulposus within the intervertebral disc is what precipitates major degenerative changes in the spine including disc herniation, disc collapse, spondylosis, and spinal instability.


Commonly there is an ‘inciting event’ such as a fall, bending over, vacuuming or trauma.


Non-skeletal


A variety of non-skeletal causes of radiculopathy exist, which can be divided into several broad categories:


  • Diabetes mellitus

  • Infections: Lyme disease, Epstein-Barr virus, Herpes simplex virus, Varicella Zoster virus

  • Inflammatory conditions: Acute inflammatory demyelinating polyradiculoneuropathy (a variant of GBS also involving the spinal nerves), chronic inflammatory demyelinating polyradiculoneuropathy (a variant of CDIP also involving the spinal nerves)

  • Vascular: arteriovenous malformation, vasculitis

  • Mass lesion or neoplasia: epidural abscess, metastasis, intradural tumour (e. g. meningioma), myeloma, lymphoma

Lumbosacral radiculopathies

Lumbosacral radiculopathy refers to damage or dysfunction of one or more lumbosacral nerve roots.


In clinical practice, the most common radiculopathies are those affecting the lumbosacral nerves between L1-S4. It is thought to affect up to 5% of the general population with an equal sex prevalence. They typically cause radicular pain in the distribution of the spinal nerve root that occurs with or without myotome weakness. Diagnosis is confirmed on imaging (e.g. MRI).


Aetiology


The typical cause of lumbosacral radiculopathies is a degenerative disease of the spine (e.g. spondylosis of the facet joints, disc herniation). Other causes may include non-skeletal aetiologies including infection (e.g. Lyme disease), vascular disorders (e.g. vasculitis), and mass lesions (e.g. lymphoma, epidural abscess).


The presentation of radiculopathy may be acute in association with movement (e.g. bending, lifting) or trauma (e.g. falling). Up to 50% of lumbosacral radiculopathies are associated with an ‘inciting event’.


Clinical features


Patients with lumbosacral radiculopathy characteristically have radicular pain (i.e. pain in the distribution of the spinal nerve root dermatome) alongside other sensory symptoms including paraesthesia or anaesthesia (i.e. sensory loss). Muscle weakness may be present that corresponds to the affected myotome but this may only be apparent on clinical examination.


The classic presentation for each lumbosacral radiculopathy is as follows:


  • L1 radiculopathy: a rare radiculopathy. Causes sensory changes in the inguinal region, but weakness is uncommon

  • L2-4 radiculopathy: discussed together because of marked overlap in symptoms. Commonly causes acute back pain that radiates around the anterior thigh. Sensory changes may be present over the anterior thigh and medial lower leg. Weakness in hip flexion, knee extension, and hip adduction can be seen. There may be a loss of the knee reflex

  • L5 radiculopathy: Most common radiculopathy in this region. Commonly causes acute back pain that radiates down the lateral aspect of the leg to the foot. Sensory changes may be present over the lateral aspect of the lower leg and dorsum of the foot. Weakness is seen in foot dorsiflexion, big toe extension, and foot inversion/eversion

  • S1 radiculopathy: Commonly causes acute back pain that radiates down the posterior aspect of the leg into the foot. Sensory changes may be present over the posterior leg and lateral foot. Weakness may be present in hip extension and knee flexion. There may be a loss of the ankle reflex

Several manoeuvres can be completed to determine whether the pain is radicular in origin, which includes:


  • Straight leg raise for L5/S1 radiculopathy: worsening radicular pain on raising the leg with the knee extended. Pain should be relieved if the knee is flexed

  • Reverse straight leg raise for L2-4 radiculopathy: worsening radicular pain on extending the leg with the patient prone

Sciatica

Sciatica is a non-specific clinical description of pain affecting the back and/or leg.


Sciatica is a commonly used clinical term that is often confused with lumbosacral radiculopathy. Sciatica is a non-specific clinical description of pain affecting the back and/or leg.


It is typically used to describe a sharp or burning pain that radiates from the buttock along the course of the sciatic nerve down the posterior/lateral leg and usually to the foot or ankle. The sciatic nerve is formed by a combination of nerve roots L4, L5, S1, S2, and S3. Therefore, involvement of any of these nerve roots alone or in combination can cause a variety of sciatica-like symptoms otherwise known as ‘radicular pain’.


Sciatica is therefore the clinical manifestation of lumbosacral radiculopathies. However, the difficulty arises in the fact that the term is used more generally as a reference to lower back pain that may be non-radicular in origin (i.e. not caused by radiculopathy). Therefore, when a patient has ‘sciatica’ it is important to determine exactly what is meant by the term and whether there is ‘radicular’ quality to the pain.

Thoracic radiculopathies

Thoracic radiculopathy refers to damage or dysfunction of one or more thoracic nerve roots.


Thoracic radiculopathies are uncommon because the movement of the thoracic vertebrae is limited by the rib cage. This means the thoracic spine is less prone to the degenerative changes of the lumbar and cervical spine that lead to radiculopathies.


Aetiology


A variety of causes may lead to thoracic radiculopathy including diabetes mellitus, disc herniation, infections, tumours, or metastatic deposits. The development of thoracic back pain is a red flag sign and should always be taken seriously. Beware of older patients with new-onset back pain that may indicate myeloma, prostate cancer, breast cancer, and lung cancer.


Clinical features


Thoracic radiculopathy is characterised by radicular pain that starts in the back and radiates around the chest in a linear pattern. Other sensory symptoms including paraesthesia and anaesthesia (i.e. sensory loss) may be experienced in the same dermatomal distribution. Muscular weakness is less noticeable with thoracic radiculopathies. Sudden back movements or increases in thoracic pressure (e.g. Valsalva maneuvers) may precipitate radicular pain.

Cervical radiculopathies

Cervical radiculopathy refers to damage or dysfunction of one or more cervical nerve roots.


Cervical radiculopathies are characterised by neck, shoulder, and arm pain with sensory changes and weakness in the distribution of the spinal nerve. The mean age of diagnosis is the 5th decade of life and there is a slightly higher prevalence in men.


The lower cervical nerve roots are more commonly affected with up to 70% of cases due to C7 nerve root involvement and 20% C6 nerve root involvement.


Aetiology


Similar to lumbosacral radiculopathies, the majority of cervical radiculopathies are due to compressive aetiologies especially spondylosis (i.e degenerative spinal changes) and disc herniation.


Nondegenerative causes can occur including infection (e.g. varicella zoster virus), tumour infiltration, or vascular causes (e.g. vasculitis).


Clinical features


Patients with cervical radiculopathy typically present with neck, shoulder and/or arm pain in association with sensory changes and muscle weakness. Disc herniation often leads to acute symptoms whereas spondylosis causes slowly progressive features.


The classic presentation for each cervical radiculopathy is as follows:


  • C5 radiculopathy: associated with pain in the neck, shoulder, and scapula. Sensory loss is usually seen in the lateral aspect of the upper arm with weakness in shoulder abduction. Biceps and brachioradialis reflexes may be affected

  • C6 radiculopathy: associated with pain in the neck, shoulder, scapula, and lateral arm, forearm, and hand. Sensory loss in the lateral forearm, thumb, and finger (pointing a gun). Weakness may be seen in elbow flexion and supination/pronation. Biceps and brachioradialis reflexes may be affected

  • C7 radiculopathy: associated with pain in the neck, shoulder, hand, and middle finger. Sensory loss in the palm, middle, and index finger. Weakness is usually seen in elbow and wrist extension. Triceps reflex may be affected

  • C8 radiculopathy: associated with pain in the neck, shoulder, medial forearm, hand, and 4th/5th fingers. Sensory loss in the medial forearm, hand, and 4th/5th digits and weak finger movements

NOTE: T1 radiculopathy is often discussed alongside cervical radiculopathies. This is because it provides innervation through the brachial plexus and contributes to sensation and movement in the upper limb. It typically causes neck pain in association with anterior arm and medial forearm sensory loss. Weakness is usually seen with thumb abduction and finger abduction/adduction.


Several important signs may be present that are suggestive of the involvement of the cervical cord (i.e. cervical myelopathy):


  • Lhermitte phenomenon: shock-like paraesthesia radiating down the spine and towards the legs that occur on neck flexion

  • Gait disturbance

  • Upper motor neuron signs in the lower limbs (e.g. increased tone, weakness, clonus, upgoing plantar)

  • Bladder/bowel dysfunction

Several manoeuvres can be completed to determine whether the pain is radicular in origin, which includes:


  • Spurling manoeuvre: positive if worsening radicular pain or paraesthesia when downward pressure is applied to the head when it is extended and rotated to the affected side. This promotes posterior disc bulging and narrows the ipsilateral neural foramina thus provoking symptoms

  • Shoulder abduction relief test: positive if a decrease or disappearance of symptoms when the arm of the affected side is raised and then the hand placed on the head

Diagnosis & investigations

Neuroimaging is critical to establish the diagnosis of radiculopathy.


The principal investigations for the diagnosis of radiculopathy is neuroimaging of the spine that allows assessment of the spinal nerve roots as they leave the spinal canal and electrodiagnostic studies (e.g. electromyography and nerve conduction studies).


Neuroimaging


Neuroimaging includes both magnetic resonance imaging (MRI) and computed tomography (CT) of the spine. It allows assessment of the spine, intervertebral discs, spinal cord, and nerve roots. CT is excellent at looking at bones and has relatively good sensitivity for detecting disc herniation that is similar to MRI. However, MRI is much better at assessing soft tissue structures and allows the assessment of nerve roots. In addition, it does not expose the patient to ionising radiation.


Given the above, MRI is typically used in the routine assessment of radiculopathies unless the patient has a contraindication. In the context of acute trauma, CT is often completed first due to it being quick and easily accessible. If the diagnosis is not clear, an MRI can be subsequently requested.


Electrodiagnostic studies


Electrodiagnostic studies include both electromyography (EMG) and nerve conduction studies (NCS).


  • EMG (evaluates muscle units): this refers to an assessment of the electrical activity of muscles. It can assess activity during rest and voluntary contraction. Records the electrical potentials generated in a muscle belly through the insertion of a needle

  • NCS (evaluates peripheral nerves): this refers to an assessment of individual peripheral nerve function. It essentially involves activating nerves electrically over several points on the skin of the upper/lower limbs and measuring the response. The test involves assessing both the size (i.e. amplitude) and speed (i.e. velocity) of signals through motor and sensory fibres

These tests are most useful in patients with more long-standing radiculopathy (at least > 3 weeks) with evidence of weakness. This enables localisation of the weakness to a spinal nerve root.

Management

The treatment of radiculopathies is highly specialised and depends on the underlying cause.


The management of radiculopathies depends on the location (e.g. lumbar versus cervical), acuity (e.g. acute versus chronic), underlying aetiology (e.g. degenerative spine disease versus vasculitis), and co-morbidities of the patient (e.g. young versus frail). It is a highly complex area, but we discuss some of the common principles below.


Non-surgical


Radiculopathies can be disabling, limiting a patient’s functional abilities, and associated with significant pain. Therefore, analgesia including neuropathic pain medications and input from the physiotherapists is essential. In patients who do not need surgery, radiculopathies may improve spontaneously with conservative measures.


Non-surgical options to consider include:


  • Optimise simple analgesia: paracetamol and NSAIDs (if no contraindications) form the cornerstone of initial analgesic management. Should be offered to all patients with pain, particularly with acute radiculopathy. Opioids should be avoided where possible

  • Neuropathic agents: neuropathic pain medications may be used, particularly with patients who have chronic disabling symptoms not responsive to simple analgesia. Options may include gabapentin or pregabalin

  • Glucocorticoids: occasionally used in acute or severe radiculopathy as a short-term treatment to improve pain

  • Activity modification: avoid activities that exacerbate pain and modify normal daily activities as appropriate

  • Physiotherapy: often tried in patients with persistent mild-to-moderate symptoms. A range of exercises may be employed. The exact timing to offer therapy depends on the location and acuity. In addition, patients with severe symptoms are often unable to participate

In patients with non-compressive aetiologies (e.g. infection, vasculitis) it is important to treat the underlying cause that may involve pharmacological agents.


Surgical


Surgery in degenerative spinal disease leading to radiculopathy may be offered to patients with progressive neurological impairment or persistent severe symptoms despite non-surgical treatments. The exact timing and type of surgery are beyond the scope of these notes, but options may include:


  • Open discectomy or microdiscectomy

  • Disc fusion

  • Laminectomy

Surgery may be indicated for other aetiologies such as epidural abscess, tumour infiltration, or metastasis.


Last updated: July 2022

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Clinical example of surgical treatment of cervical osteochondrosis with discogenic radiulopathy

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