NECK

CHAPTER 2

Neck

EPIDEMIOLOGY OF NECK PAIN

NECK PAIN IN THE GENERAL POPULATION

Prevalence

• ~15% (12%–70% depending on studies) in the general population (1)

• ~5 % have activity limitations (2) and 1.7% are limited in their abilities to work

• Chronic neck pain (>6 months): female > male, increase with age (controversial)

Chronic neck pain: 15% to 40% of patients with acute neck pain after motor vehicle accident (MVA) and 5% to 7%; disability

• New disability claims per year from neck pain (3,4): 600 per 100,000 (5)

NECK PAIN IN ATHLETES (6)

Prevalence and common causes

• Cervical strain/sprain: (most common [MC] cause of neck pain in athletes):

Whiplash disorder with acceleration–deceleration-type injury

• Stinger/burner syndrome: MC cause of transient neuropathic pain

Occurs in 65% of college football players, high recurrence rate up to 87%

• Myofascial pain in the neck–shoulder girdle

Common in cyclists (~60%), caused by hyperextension of the neck in horizontal riding position

• Discogenic neck pain: uncommon

Spinal cord injury (SCI)

• Cervical cord neurapraxia (CCN): 7 per 10,000 football participants (7)

• SCI: rare, mainly caused by spear tackling (axial loading)

~80% drop after spear tackling prohibited in 1976

NECK PAIN AT WORK (1)

Prevalence

• Highly prevalent and continues to increase

Risk factors for chronic pain (>6 months)

• Female > male, age, high quantitative job demands, low-coworker support, repetitive work, nonfixed salary, prolonged sitting, poor ergonomics, previous musculoskeletal (MSK) comorbidities, depressive symptoms

• Crane operators (upto 70%), nurses, and office workers

Cervical disc injury

• Higher in drivers than other occupations

• May be related to vibrations and road shocks, twisting and acceleration/deceleration, or whiplash accident rather than heavy lifting (8)

Workplace modifications: No clear evidence that interventions aimed at modifying work stations and worker posture are effective in reducing incidence of neck pain in workers

DIFFERENTIAL DIAGNOSIS

Differential diagnosis based on the location and radiation of neck pain (Flowchart 2.1)

Working definition of neck region: superior nuchal line to T1 spinous process, laterally by medial scapular border

FLOWCHART 2.1

Differential diagnosis of nontraumatic neck pain.

UNUSUAL CAUSES OF NECK PAIN

• Considered if symptoms are not explained by other well-established causes

• Cervical spine: diffuse idiopathic skeletal hyperostosis (DISH), Paget disease, and spondylosis, subluxation of the lateral atlantoaxial joint, joint of Luschka lesion, synovial cyst, subluxation of the facet joints

• Muscle/tendon: torticollis, longus colli tendonitis (retropharyngeal tendinitis), temporalis muscle, hyoid bone or muscle (sternohyoid and omohyoid) syndrome for anterior neck pain

• Soft tissue: infection of the oral cavity, oropharynx, and glands (lymphadenitis, sialadenitis, and thyroiditis); polymyalgia rheumatica

• Referred pain (Figure 2.1)

Referred pain from temporomandibular joint (TMJ) dysfunction and trigerminal neuralgia

Migraine headache, basal ganglia disease

• Carotidynia (11,12)

Dull, throbbing pain directly over the carotid artery (either unilateral or bilateral) with followings

Exacerbated with light pressure ± ipsilateral headache, self-limiting <2 weeks

One of three findings (tenderness, swelling, and increased pulsations) on carotid artery

Differential diagnosis: carotid aneurysm, carotid body tumor, carotid dissection, acute carotid occlusion, large vessel vasculitis (giant cell arteritis), and fibromuscular dysplasia

Workup; emergency room (ER) referral, duplex imaging (initial) for extracranial carotid arteries, and CT or MRI

FIGURE 2.1

Extrinsic causes of neck, shoulder, and arm pain.

Source: Adapted from Ref. (13). Firestein GS, Kelley’s textbook of rheumatology. 9th ed. Philadelphia, PA: Saunders Elsevier; 2012.

NEUROLOGICAL SYMPTOMS ASSOCIATED WITH NECK PAIN

Sensory symptoms

• Differential diagnosis for neck pain with sensory symptoms (numbness, tingling, pins/needles, or burning)

Cervical radiculopathy: sensory symptoms present in dermatomal distribution

Referred pain from myofascial pain mimicking positive sensory symptoms (Figure 2.2)

Concomitant focal entrapment neuropathy (carpal tunnel syndrome [CTS] or ulnar neuropathy) with localized axial neck pain mimicking radiculopathy

Other unusual causes

Numb chin syndrome (chin and inferior lip): mental/inferior alveolar neuropathy by jaw metastasis or vasculitis (14)

• Differential diagnosis for ataxic gait with/without neck pain

Cervical myelopathy: because of alteration of dorsal column; (+) long tract signs (Hoffman’s reflex, hyperreflexia, ankle clonus)

Chiari I malformation; headache/neck pain is more common than ataxia and scoliosis (next common) (15)

Motor symptoms

• Differential diagnosis for extremity weakness: radiculopathy, myelopathy, radiculomyelopathy, or pain-induced subjective weakness

• Differential diagnosis for regional (neck) involvement: dropped head/neck syndrome, and torticollis/cervical dystonia (stiffness)

Differential diagnosis for dropped head/neck syndrome (16)

Anterocollis (cervical spine)/anterocaput (head): involuntary, nonfixed anteflexion of the head, frequently associated with pain (17)

Motor neuron disease: amyotrophic lateral sclerosis (ALS), postpolio syndrome; 1% of patients with motor neuron disease; presents with dropped head as an early feature

Peripheral nerve disease: chronic inflammatory demyelinating polyneuropathy (CIDP)

Neuromuscular disease: myasthenia gravis (anti-Ach R Ab+, anti-Musk Ab+), myopathy

Myopathy

– Idiopathic isolated neck extensor myopathy: MC cause of dropped head syndrome

– Polymyositis, inclusion body myositis

– Facioscapulohumeral muscular (FSH) dystrophy, myotonic dystrophy, Nemaline myopathy, mitochondrial myopathy, carnitine deficiency, severe hypokalemic myopathy

– Focal posterior cervical myopathy

Others

– Increased thoracic kyphosis with loss of compensatory cervical lordosis

– Ankylosing spondylitis

– Malignancy, Parkinson’s disease (18)

• Etiologies of excessive cervical kyphosis

Degenerative; normal cervical lordosis decrease with age

Neurogenic; dropped head syndrome

Traumatic; fracture (burst) and posterior tension band injury (intraspinatus and supraspinatus ligament), jumped facet

Congenital

Post-laminectomy (less common with instrumentation)

• Etiologies of torticollis (twisting of the head and neck) (17)

Nonparoxysmal torticollis (19)

FIGURE 2.2

Typical referred pain patterns from myofascial pain syndrome: (A) trigger points with referred pain below elbow and (B) trigger points with referred pain above elbow.

Source: Adapted from Refs. (20,21).

Congenital torticollis

– Breech and difficult delivery; MC cause

– Incidence: 0.3% to 2% (>80% muscular origin)

– Other manifestations: congenital hip dysplasia (10%–20%), craniofacial asymmetry (80%), and developmental disorders (eg, attention deficit hyperactivity disorder)

Osseous torticollis: Klippel–Feil syndrome, cervical vertebral fracture, atlantoaxial rotatory subluxation

Secondary torticollis: brain lesions in posterior fossa (eg, brain stem, cerebellar tumor) or basal ganglia, hypoxic ischemic encephalopathy, spinal cord lesions (eg, tumor, syrinx), brachial plexus lesion, ocular torticollis (eg, superior oblique palsy, strabismus, spasmus nutans), soft tissue pathology (nonmuscular, infectious: retropharyngeal abscess)

Paroxysmal torticollis

Benign, spasmodic (cervical dystonia), Sandifer syndrome (rare pediatric manifestation of GERD), drug induced (eg, neuroleptics), conversion disorder, increased intracranial pressure (eg, pseudotumor cerebri)

Cervical dystonia

– Incidence ~9 per 100,000, female > male, more common in Whites, onset around 40 years (17)

– Primary or secondary; Huntington or Wilson disease

Other symptoms

• Differential diagnosis for multiple joint pain (polyarthralgia) with neck pain

Systemic inflammatory arthropathy usually accompanied by morning stiffness and other systemic manifestation and associated cutaneous manifestation

Rheumatoid arthritis (RA): hand and foot involvement (MC) followed by cervical spine (upper > lower)

Ankylosing spondylitis: lumbar spine and chest (limited motion and expansion) involvement (MC) followed by cervical spine

• Cervicogenic headache (22)

Location: neck and occipital, unilateral (or bilateral) without side shift, moderate to severe, related to neck movement and posture

Involved structures: facet joint (C1–3), uncovertebral joints, disc, cervical/rectus capitis muscle, nerve root, vertebral artery, and ligamentum nuchae

Decreased cervical range of motion (ROM), tenderness over C2/3 cervical facet joint

Often responsive to occipital N, facet joint, or nerve root blocks

Requires work up for brain pathologies

• Pseudoangina pectoris or breast pain: referred pain from C6–7 nerve root irritation (23), unusual cause of chest pain, diagnosis of exclusion

• Altered equilibrium, visual symptoms and hearing: because of irritation of the plexuses surrounding the vertebral and internal carotid arteries

• Differential diagnosis for swallowing difficulty (24)

Cervical spine disease: spondylosis, DISH, ankylosing spondylitis

Mechanical blocking with osteophytes, syndesmophytes

Prevertebral abscess

Iatrogenic from cervical collar: restrict laryngeal movement

Rheumatologic disease

Sjögren’s syndrome, Behcet’s disease, systemic lupus erythematosus (SLE) with xerostomia, ulceration, candidiasis

RA involving the TMJ joint (painful mastication)

ANATOMY

REGIONAL ANATOMY (25) (FIGURE 2.3)

Triangles of neck divided by sternocleidomastoid (SCM) muscle

• Anterior triangle of neck bordered by SCM (posterior), mandible (superior), and midline of neck (anterior) (see Figure 2.3)

Midline of neck

Hyoid cartilage (C3 level), thyroid cartilage (C4–5 level), 1st cricoid ring cartilage (C6 level)

Chin with neutral head position (C4 level)

Superficial structures

Nerves: vagus nerve, hypoglossal (CN 12) nerve, ansa cervicalis

Vessels: common carotid artery and internal jugular vein within the carotid sheath

Deeper structures

Cervical sympathetic chain/ganglion: deep to carotid sheath (not within the sheath) and superficial to longus coli muscle

Thyroid gland, superior thyroid artery, superficial laryngeal nerve, inferior thyroid artery, recurrent laryngeal nerve, and thyroid vein

• Posterior triangle of neck bordered by trapezius (posterior border), SCM (anterior), and clavicle (inferior)

Superficial structures

Nerves: accessory nerve, greater auricular, lesser occipital nerve, supraclavicular nerve, transverse cervical nerve, superficial cervical plexus (exit at the midpoint of posterior border of SCM muscle)

Vessels: occipital artery and external jugular vein

Deeper structures

Nerves: phrenic nerve, transverse cervical artery, brachial plexus (exits between the anterior and middle scalene muscles near the point where external jugular vein crosses the SCM muscle)

Vessels: subclavian artery and vein, suprascapular artery

1st rib: palpable at ~3 cm lateral to the insertion of the SCM clavicular head

SPINE COMPLEX (BONE AND JOINT)

C1 (atlas) and C2 (axis) (13)

• C1: no vertebral body, no spinous process, consists of anterior and posterior arch

• C2 has odontoid process (dens), which articulates with the posterior aspect of the anterior arch of the atlas.

• Atlantoaxial joint: true synovial joint, susceptible to inflammatory arthritis (RA)

Atlantoaxial joint stabilizer: transverse ligament (principal), alar and apical ligaments (secondary)

There is no intervertebral disc between the atlantoaxial and atlanto-occipital joint. Because of the lack of conferred stability from intervertebral discs, destructive inflammatory arthritis involving synovial joints may result in instability

Subaxial cervical spine: C3 to C7 (Figure 2.4)

• Spinous process

The C7 spinous process is the largest and the most prominent (easily palpable)

The spinous processes of C3 through C6 are bifid, whereas the C7 spinous process usually is not

Five articulations between vertebrae: intervertebral disc, two uncovertebral joints (unique in C spine), and two facet (zygapophyseal) joints

• Uncovertebral joint (joint of Luschka)

Well visualized in oblique x-ray anterior to the intervertebral foramen (26)

Osteophytes from the uncovertebral joint often project into the intervertebral foramen encroaching the cervical nerve root (common in C4–6) and radicular artery

• Transverse process

Has anterior and posterior tubercles

The discrepancy between the prominent anterior tubercle of the C6 vertebra and the rudimentary anterior tubercle of the C7 vertebra: landmark for ultrasound (US) examination

• Vertebral artery: between longus colli and scalene anterior caudally enter to the transverse foramen between C6 and C7 levels (MC)

• Facet joint (27; Figure 2.5)

Diarthrodial, synovial joints with hyaline cartilage, intervening menisci, and joint capsule susceptible to degenerative changes and inflammatory arthritis

The cartilage and the synovial lining are aneural, whereas the joint capsule is highly innervated by the dorsal ramus

Joint innervation: dorsal rami of two vertebrae above and below

Exception

– C2–3 innervated by two different branches of C3 dorsal ramus and lesser occipital nerve (branch of C2 ventral ramus)

– Atlanto-occipital and Atlantoaxial levels by ventral rami of C1 and C2

More mechanoreceptors in cervical facet than lumbar facet

A delta and C fibers clustered in the dorsolateral aspect of the capsule

Facet orientation

Cervical: A, B (oblique axial, 45° from the transverse plane, anterior superior to posterior inferior), thoracic: C, D (coronal), lumbar: E, F (oblique sagittal)

See Figure 2.5. The orientation of these facet joints influences the ROM of the joint

FIGURE 2.3

Surface anatomy of the (A) anterior neck and (B) posterior neck.

Source: Adapted from Ref. (28). Mays MA, Tepper SJ. Occipital nerve blocks. In: Narouze SN, ed. Interventional Management of Head and Face Pain: Nerve Blocks and Beyond. New York, NY: Springer; 2014:29–34.

FIGURE 2.4

Cross-sectional view of cervical spine. Uncinate process (U) with uncovertebral joint forms ventral wall of foramen. Spinal nerve exits dorsal to vertebral artery (A).

FIGURE 2.5

Facet joint orientation in cervical (A, B), thoracic (C, D), and lumbar spines (E, F).

Source: Adapted from Refs. (29,30).

Aging changes (31)

Start after 2nd decade, cartilage loss, subchondral bone thickening, osteophytes and loss of meniscus, more in the middle and lower segments

• Intervertebral disc (32)

Disc consists of the outer annulus fibrosus and the inner nucleus pulposus

The annulus fibrosus consists of type I collagen, provides tensile strength

– Innervated by the sinuvertebral nerve, formed by branches of the ventral nerve root and the sympathetic plexus (33)

The nucleus pulposus consists of type II collagen and proteoglycans, which interact with water to resist compressive stress

Pressure within the disc is greater with forward flexion and sitting, which can cause discomfort in setting of disc herniation

Blood supply: become avascular by 2nd decades, then nutrient supplied by diffusion

Cervical spinal canal and spinal cord

• Lower cervical spine has smaller space for spinal cord than upper cervical spine

Spinal cord occupies up to 75% of canal (vs <50% in the atlas level)

Biggest diameter of posterior epidural space: C6–7 > C7–T1

• Mid-sagittal diameter is decreased by 2 to 3 mm with neck extension

Hyperextension injuries: usually with congenital spinal stenosis, especially in individuals with additional narrowing because of cervical spondylosis acute cervical myelopathy

LIGAMENT

Atlanto-occipital membrane (dense anterior and thin posterior): limits excessive flexion and extension of atlanto-occipital articulation (about 30°)

Transverse ligament: permit the atlas to rotate around the odontoid process

• A tear in this ligament has the same effect as a fractured odontoid process

• The stability of the atlantoaxial joint depends almost entirely on ligaments

• Frequently dysfunctional in RA and Down syndrome

Posterior longitudinal ligament (PLL): resist hyperflexion, ossification (ossification of posterior longitudinal ligament [OPLL]) can cause cervical myelopathy

Anterior longitudinal ligament (ALL): resist hyperextension

Ligament flavum: thickening can cause spinal stenosis

Supraspinous ligament: C7 to sacrum, above C7: ligament nuchae

NERVE: ROOT AND PLEXUS

Nerve innervation of the spine structure (33)

• Sinuvertebral nerve: innervates anterior vertebral body, external annulus, ALL, PLL, dura mater, and blood vessels

Arise from somatic (from ventral ramus) and autonomic root (from vertebral nerve in C1–3 levels or the gray rami communicants from sympathetic trunk and stellate ganglion in the lower cervical level)

Innervates more than one level by interconnection with nerves from other levels

• Medial branch of the dorsal ramus: innervates facet (the same level and the level below), interspinous ligament, and deep paraspinals (segmental multifidi and rotators) muscle

Spinal nerve

• C1–7 spinal nerves exit above their corresponding vertebrae, C8 exits between C7 and T1, T1–L5 exit below their corresponding vertebrae

• Dorsal and ventral root spinal nerve dorsal and ventral ramus

Ventral (anterior) rami form cervical and brachial plexus

Dorsal (posterior) rami innervate paraspinal muscles and facet joints, and branch to greater occipital and 3rd occipital nerves

Cervical root: tethered in the intervertebral foramen (possible contributor for root avulsion) versus lumbar root: not tethered in the intervertebral foramen

• Cervical plexus (32; Figure 2.6)

Ventral primary rami of C1–4

Located deep to the internal jugular vein, the deep fascia and SCM and anterior to scalenus medius and levator scapulae (replace with picture)

Superficial cervical plexus: outside the prevertebral fascia, posterior margin of middle of SCM muscle

Each ventral ramus, except the first, divides into ascending and descending parts that unite in communicating loops

• Dorsal rami from cervical spinal nerves (34) (see Figure 2.3B)

Greater occipital nerve: from medial branch of C2 (sometimes C3) dorsal ramus

Run over the obliquus capitis inferior/rectus capitis posterior major muscle, pierce through the semispinalis muscle and trapezius aponeurosis

Innervates semispinalis capitis exclusively

Becomes subcutaneous slightly inferior to the superior nuchal line by passing above an aponeurotic sling composed from the trapezius and SCM muscles. At this point, the greater occipital nerve is immediately medial to the occipital artery

Third occipital nerve: from C3 dorsal ramus, ascend the medial to the greater occipital nerve, innervates rostral end of the skin of the neck

C3–5 dorsal rami: innervate splenius capitis and facet joints, can cause occiput and posterior neck pain

FIGURE 2.6

(A) Cervical plexus and (B) brachial plexus.

Source: Adapted from Ref. (32). Mancall EL, Brock DG, Gray H. Gray’s clinical neuroanatomy: the anatomic basis for clinical neuroscience. Philadelphia, PA: Elsevier, xiii, 433 pages.

• Brachial plexus

Origin: C5 to T1 ventral rami, variations: prefixed (C4 included), postfixed (T1 included)

Course: emerges between the anterior and middle scalene muscles, courses behind the clavicle, lies on the serratus anterior and subscapularis muscle and runs with axillary artery

Divided by clavicle: trunks above clavicle, cords below clavicle

• Nerve root itself is not pain sensitive, but dural sheath is

MUSCLE

Anterior and anterolateral cervical muscles

• Superficial: platysma, SCM (neck flexion with bilateral contraction, contralateral rotation/ipsilateral flexion with unilateral contraction)

• Anterior deep: longus capitis, colli, rectus capitis anterior, lateralis

• Lateral deep: anterior, medius, and posterior scalene (ipsilateral flexion with SCM)

• Hyoid muscles: muscles for swallowing and synergist for head flexion

Suprahyoid muscles (mylohyoid, stylohyoid): pull the hyoid bone upward and forward, widen the pharynx, and close airway

Infrahyoid muscles (omohyoid, thyrohyoid, sternohyoid, and sternothyroid): strap muscles of the larynx, return the hyoid bone and larynx back to the original position

Posterior cervical muscles

• Superficial: trapezius muscle

• Intermediate: splenius capitis and splenius cervicis

Splenius: acts as a group to extend or hyperextend the head, unilateral contraction rotates and bends head laterally toward the same side

• Deep: erector spinae

Iliocostalis cervicis, longissimus capitis/cervicis, and spinalis cervicis (lateral to medial)

Primary extensor and controls forward flexion via eccentric contraction

Spinalis cervicis: unilateral contraction flex the neck ipsilaterally, bilateral contraction extends the neck

Longissimus: capitis extends head and turns face toward the same side; cervicis and thoracis act together to extend vertebral column

Iliocostalis: unilateral contraction flex the neck ipsilaterally, bilateral contraction extends the neck

• Transversospinales (from transverse processes to spinous processes of higher level)

Semispinalis cervicis/capitis, multifidus, rotator and interspinalis, intertransversarii

Flex to the same side and rotate to the opposite side with unilateral contraction. Extension of the vertebral column with bilateral contraction

Semispinalis cervicis: acts synergistically with SCM muscles of opposite side

• Suboccipital muscles (rectus capitis posterior minor, major, oblique capitis superior/inferior); innervated by the suboccipital nerve (dorsal primary rami of C1)

Head and neck movement in summary

• Lateral head movement: SCM and scalene muscle

• Head extension: splenius, trapezius, semispinalis, and longissimus muscle

• Head flexion: SCM, synergistic movement with supra and infrahyoid muscle

• Neck flexor: longus capitis and longus coli muscle

FASCIA (35)

Deep cervical fascia

• Encircle the neck completely

• Composed of superficial, middle, and deep layers

• Superficial layer: envelops the trapezius and SCM, also called an investing layer

The superficial layer extends to the trapezius muscle, continues anteriorly over the posterior triangle, and divides to encircle the SCM muscle

Clinical implication

Anatomic basis of the subcutaneous cervical plexus block in the posterior to middle of SCM muscle: no difference in efficacy between the injection under the investing fascia as the anterior triangle may not have deep investing fascia (36)

• Middle layer: also called the pretracheal layer

Encloses the omohyoid and strap muscles and continues laterally to the scapula

The thyroid gland, larynx, trachea, pharynx, and esophagus are enclosed by the visceral fascia of the middle layer

• Deepest layer: prevertebral layer and carotid sheath, barrier for infection

Prevertebral layer: encloses the scalenus muscles, brachial plexus, sympathetic chain, longus colli muscle, and ALL other structures surrounding vertebral column

Anatomic basis for sympathetic nerve block under the prevertebral layer

Carotid sheath: contains carotid artery, internal jugular vein, and vagus nerve (Figure 2.7)

FIGURE 2.7

Cross-sectional view of neck.

BLOOD SUPPLY

Vertebral artery

• Arises from the subclavian artery, courses through the C6 transverse foramen cephalad, passing anterior to the emerging cervical nerve root at each level lies behind the lateral mass of C1 enters the foramen magnum and rejoin to form the basilar artery

• Variable presence, more common on the left at C3 and C6 and on the right at C5 and T1

• Anterior spinal artery

At the level of foramen magnum, branches anterior spinal artery which descends anterior to the spinal cord, takes several radicular arteries, supplies anterior two-thirds of spinal cord

Radicular arteries (medullary feeder arteries) arise from the vertebral artery at the lower level and ascending cervical artery, enter through neural foramen and join the anterior spinal artery

• Posterior spinal artery: two posterior spinal arteries originate from the posterior inferior cerebellar artery or the vertebral arteries

• Clinical implication in neck pain

Vertebral artery dissection

Severe neck pain with posterior circulation signs such as nystagmus, vertigo, drop attacks, dysarthria, and visual impairment

Transient symptoms: associated with head position and a critical reduction in blood flow, can result in a cerebellar infarction (37)

Cautious in occipital nerve block near C1–2 level, transforaminal epidural block and stellate ganglion block

Carotid artery (38)

• The right common carotid artery (CCA) arises from the brachiocephalic artery, while the left CCA usually originates directly from the aortic arch

• The common carotid arteries ascend through the mediastinum and lie posterior and medial to the internal jugular veins in the neck. Diameters of the CCA are ~6 to 8 mm

• The CCA bifurcates into the external carotid artery (ECA) and internal carotid artery (ICA) typically at the upper edge of the thyroid cartilage (between C3 and C5)

• The ICA arises posterolateral to the ECA in approximately 90% of individuals; a medial origin is present in the remaining 10%

• Clinical implication

Carotid dissection; headache (earliest and most common) with/without neck pain