Causes and Sources of Neck Pain

The source of the pain refers to the anatomical structure which has nociceptive activity leading to pain perception. A lot is known about possible sources, but not a great amount about actual sources of neck pain. The cause of the pain is the disease process or disorder that is responsible for the nociceptive activity. A lot is known about rare causes, but not common causes of neck pain.
==Sources==
*Any structure that has a nerve supply may become a source of pain
*The innervated structures are the: facet joints, atlanto-occipital joints, atlanto-axial joints, transverse ligament, posterior neck muscles, cervical intervertebral discs, vertebral bodies, anterior and posterior longitudinal ligaments, the dura mater of the cervical spinal cord, the prevertebral muscles, and the vertebral and carotid arteries.
*In acute neck pain, it is not known how often each structure is a source of pain.
*In chronic neck pain, some data are available.
==Causes==
*Textbooks often list possible causes of neck pain, but without any evidence to support the causes nor prevalence rates
*Most causes listed in textbooks are either rare or controversial.
===Serious but Rare Causes===
Serious but rare causes are tumours and infections
*Tumours - can grow and threaten the spinal cord, compromise the vertebral column stability, or metastasize.
*Infections of the bones, joints, discs, and meningitis of the cervical dura mater - can become septic, or form an abscess that threatens the spinal cord or vertebral column stability.
*These are usually recognisable on imaging and/or clinical grounds.
*There are no experimental data, but rather clinical experience that treatment results in resolution of the neck pain
*There are no studies indicating the prevalence of tumours and infections, but are likely quite rare.
*There is limited information as to the effect on spinal osteomyelitis and epidural abscess as it specifically applies to the neck rather than the spinal column in general.
*Bogduk estimates that the prevalence of undiagnosed tumours or infections is substantially less than 0.4%.
*Epidural abscess: may present with neck pain prior to neurological signs. Usually the cause is iatrogenic or from a distant source.
*Epidural haematoma: this can occur spontaneously or after a trivial event such as sneezing or straining. Theories as to the cause include epidural vein or artery rupture and increase in epidural pressure. Risk factors are anticoagulant therapy including excessive garlic consumption. The presenting feature may be simple neck pain, but imaging should wait until definite neurological signs which usually occur within hours of pain onset. This is a neurosurgical emergency with the aim of decompressing the cord.
===Valid but Rare or Unusual Causes===
*Rheumatoid Arthritis: this may involve the upper cervical spine, but the diagnosis is usually already evident by this stage because usually peripheral manifestations occur prior to cervical disease. C1-2 segment involvement can be a serious threat but has a favourable prognosis
*Ankylosing Spondylitis: This usually occurs late in the disease process and so the diagnosis is usually already evident. 10% present with neck pain as the initial manifestation.
*Reiter's Syndrome: Cervical spine involvement is uncommon, and usually affects the C1-2 segment and craniocervical junction.
*Psoriatic Arthritis: Similar to rheumatoid arthritis and ankylosing spondylitis. Rare to have neck pain alone
*Gout and other crystal arthropathies: spinal involvement is rare.
*Polymyalgia Rheumatica: The neck can be involved but it does not by definition only involve the neck
*Calcific Tendinitis of the Longus Colli Muscles: Also known as retropharyngeal tendonitis. There is inflammation and oedema of the upper portions of longus colli (not just the tendons, so its a misnomer) from C1-C4 and sometimes down to C6. Very rare 1 in 400,000 per year. Often calcification opposite C2 vertebra. Bogduk thinks that the calcium is an epiphenomenon rather than the cause of pain.
*Cervical Spine Fractures: Prevalence of less than 0.4%.
===Torticollis===
*Torticollis is diagnosed by the presence of a characteristic rotatory deformity.
*It is not a differential diagnosis of neck pain because without the rotatory deformity it is not torticollis
*However torticollis has its own differential diagnosis: mechanical cervical causes such as extrapment of a meniscoid in a cervical facet joint, atlanto-axial subluxation, or vertebral osteomyelitis. Also non-cervical causes such as basal ganglion disorder or phenothiazine toxicity.
===Detectable but Questionable Disorders===
*Diffuse Idiopathic Skeletal Hyperostosis: Generally causes stiffness and dysphagia rather than neck pain. Ossification of the posterior longitudinal ligament can also be asymptomatic, but may present with a myelopathy.
*Paget's Disease: This can involve the spine but it is often painless.
*Synovial cysts: These do not cause neck pain but can cause myelopathy or radiculopathy.
===Spondylosis===
*Spondylosis is a disorder of the vertebral bodies and intervertebral discs, characterised by osteophytes around the vertebral margins. Osteoarthritis in contrast is a disorder of the synovial joints of the cervical spine (zygapophyseal joints and atlanto-axial joints), characterised by osteophytes, joint narrowing, and subchondral sclerosis. Collectively the two conditions are referred to as degenerative joint disease.
*Cervical spondylosis occurs with increasing frequency with increasing age in asymptomatic individuals, most commonly affecting C5-6 and C6-7.
*In some studies there is a very low odds ratio for disc degeneration and osteoarthritis as predictors for neck pain - 1.1 and 0.97 respectively for women, and 1.7 and 1.8 respectively for men.
*In other studies there is no significant difference between symptomatics and asymptomatics.
*Uncovertebral osteophytosis tends to be more clinically relevant for foraminal stenosis than zygapophyseal joint osteoarthritis. Uncovertebral osteophytosis is related very closely to disc degeneration.
===Neurological Causes===
*Conditions not part of the differential of neck pain per se, because the hallmark feature is neurological deficit
**Cervical Radiculopathy and Thoracic Outlet Syndrome: sensory and motor deficits in the upper limb
**Cervical Myelopathy: loss of function in the lower limbs
**Spinal Cord Tumours: Loss of function in either the upper or lower limbs depending on location
*Conditions causing neck pain as presenting complaint but only in case report(s)
**Neuroma on proximal stump of injured long thoracic nerve and spinal accessory nerve: This affects deep sensory afferents that relay to the cervical segments. The motor deficits may be mild, and so the presenting complaint may simply be neck pain.
**Aberrant vertebral artery causing irritation of dorsal root entry zone of sensory roots of the spinal accessory nerve
**Dural irritation from subarachnoid haemorrhage
**Dural irritation from cerebral tumour
===Spurious Conditions===
*Soft-tissue injuries: This is spurious because it only means neck pain in the absence of fracture and so it is not specific enough
*Whiplash: This term refers to aetiology rather than the cause
*Cervical strain: Not specific enough with regards to the nature of the lesion or its location
*Psychogenic pain: No diagnostic criteria
*Postural abnormalities: Lacks reliability and validity
*Fibrositis and myofascial pain: Lacks reliability and validity
*Tendonitis of the sternocleidomastoid or longus colli: Lacks diagnostic criteria
*Fibromyalgia: Cannot be used for neck pain alone, must be in the presence of widespread pain
*Hyoid bone syndrome: No controlled studies tested validity of the criteria which is complete relief of pain with anaesthetic injection of the region of the greater horn of the hyoid bone where the patient is tender. Prevalence is unknown.
===Vascular Disorders===
*Internal carotid artery dissection: Usually presents with headache but in 6% of cases it presents as neck pain, or in 17% as neck pain plus headache.
*Vertebral artery dissection: Neck pain is the presenting complaint in 50-90%, but it is usually accompanied by occipital region headache or sometimes other regions
*Dissecting thoracic aortic aneurysm: Chest pain is usually present, but neck pain is the presenting complaint in 6% of cases.
===Whiplash===
*Synonyms
**IASP recommend term "acceleration-deceleration injury" for neck pain with a distinctive cause, but literature still uses term whiplash.
**Australian Acute Musculoskeletal Pain Guidelines from 2003 use term whiplash-associated neck pain
*Vast majority of patients recover
*Minority develop chronic pain
*Plausible biomechanics for injury during whiplash
*Fractures 
**Rare. no fractures in 283 whiplash patients, implies prevalence of less than 1.3%. Another study 2 fractures out of 2788, prevalence of 0.07%.
**Majority involve upper cervical spine, include fractures of odontoid process, C2 laminae and articular processes, and occipital condyles. 
**Others include fracture of lower cervical spinous processes.
*Prevertebral injury: 
**prevertebral haematoma +/- avulsion fracture of anterior osteophyte. 
**oesophageal puncture from prominent anterior osteophyte.
*Vascular injury: 
**vertebral artery or internal carotid artery can dissect. 
**Vertebral artery injured with or without C2 fracture adjacent to the artery. 
**Injury to cervical portion (third part) of the vertebral artery can result in basilar artery thrombosis. 
**Internal carotid artery can be strangulated by the hypoglossal nerve.
===Cervical Pain of Unknown Origin===
*The IASP term for pain without an known origin.
*Australian Acute Musculoskeletal Pain Guidelines from 2003 recommend term idiopathic neck pain.
*Pain stemming from cervical spine but no specific diagnosis.
===Valid Causes that Require Invasive Tests to Confirm===
*Cervical discogenic pain
*Cervical zygapophyseal joint pain ~60%
*Cervical muscle sprain (IASP strict criteria)
*Cervical segmental dysfunction (IASP strict criteria)
==Summary==
*Any structure in the cervical spine that is innervated is a potential source of pain
*Cervical spondylosis is not a legitimate cause of neck pain
*Serious and identifiable causes of neck pain are rare
*The causes of common neck pain are unknown
==Bibliography==
*Bogduk, Nikolai, and Brian McGuirk. Management of acute and chronic neck pain : an evidence-based approach. Edinburgh New York: Elsevier, 2006.
Category:Cervical Spine