Cervical Strain Flashcards
Background
Cervical strain is one of the most common musculoskeletal problems encountered by generalists and neuromusculoskeletal specialists in the clinical setting.
One cause of cervical strain is termed cervical acceleration-deceleration injury; this is frequently called whiplash injury.
Whiplash, one of the most common sequela of nonfatal car injuries, is one of the most poorly understood disorders of the spine, and the severity of the trauma is often not correlated with the seriousness of the clinical problems. A history of neck injury is a significant risk factor for chronic neck pain. Pretorque of the head and neck increases facet capsular strains, supporting its role in the whiplash mechanism.
The Quebec Taskforce on Whiplash-Associated Disorders has suggested the following system for classifying the severity of cervical sprains:
0: No neck pain complaints, no physical signs
1: Neck pain complaints, only stiffness or tenderness, no other physical signs
2: Neck complaints and musculoskeletal signs (decreased range of motion [ROM] and point tenderness)
3: Neck complaints and neurologic signs (weakness, sensory and reflex changes)
4: Neck complaints with fracture and/or dislocation
Relevant anatomy and physiology
Consistent with known biologic models, injuries to bony, articular (discs and facets), nerve (including root and spinal cord), and soft (ligament, tendon, muscle) tissues of the cervical spine are the most likely sources of dysfunction and pain. Cervical strain is produced by an overload injury to the muscle-tendon unit because of excessive forces on the cervical spine. The cause is thought to be the elongation and tearing of muscles or ligaments. Secondary edema, hemorrhage, and inflammation may occur.
Many cervical muscles do not terminate in tendons but attach directly to the periosteum. Muscles respond to injury by contracting, with surrounding muscles recruited in an attempt to splint the injured muscle. Myofascial pain syndrome, which is thought to be the resultant clinical picture, may be a secondary tissue response to disc or facet-joint injury.
Facet capsular ligaments have been shown to contain free (nociceptive) nerve endings, and distending these ligaments by administering facet joint injections has produced whiplash-like pain patterns in healthy individuals. The cervical facet capsular ligaments may be injured under whiplashlike loads of combined shear, bending, and compression forces; this mechanism provides a mechanical basis for injury caused by whiplash loading
Chronic Pain with Cervical Strains
Chronic pain associated with cervical strains is most likely to affect the zygapophysial (facet) joints, intervertebral discs, and upper cervical ligaments. The C2-3 facet joint is the most common source of referred pain in patients with a dominant complaint of occipital headache (60%). The C5-6 region is the most common source of cervical, axial, and referred arm pain. Cervical facet joint pain is typically a unilateral, dull, and aching neck pain with occasional referral into the occiput or interscapular regions. The cervical facet joints can be responsible for a substantial portion of chronic neck pain. The cervical facet joints refer pain overlapping with both myofascial and discogenic pain patterns.
Neuroanatomic Studies
Neuroanatomic studies reveal that the facet joint is richly innervated and contains free and encapsulated nerve endings. The facet capsule is richly innervated with C fibers and A-delta fibers. Many of these nerves are at a high threshold and likely to indicate pain. Local pressure and capsular stretch can mechanically activate these nerves. These neurons can be sensitized or excited by naturally occurring inflammatory agents, including substance P and phospholipase A.
Physiological changes that lead to Cervical and Spinal Pain
Physiologic changes in the spinal cord, particularly the pain complexes of the dorsal horn, implicate excitatory amino acids, such as substance P, glutamate, gamma-aminobutyric acid (GABA), and N -methyl-D-aspartate (NMDA), as well as other factors that sensitize the dorsal horn in chronic pain. The mechanism is massive input of noxious stimuli from cervical spine injury.
In lumbar spine studies, inflammatory cytokines are found at high levels in facet joint tissue when a degenerative disorder is present. Facet joints are covered by hyaline cartilage and enclosed with synovium and joint capsules. This basic structure is found throughout the spine and in the joints of the arms and the legs.
Classic mechanism of whiplash injury
A collision in any direction can cause chronic whiplash.
In a clinical review, Barnsley and colleagues described the classic whiplash scenario in which the patient’s car has been struck from behind (ie, rear ended).
This type of accident typically occurs in the following manner:
1. At the time of impact, the vehicle suddenly accelerates forward. About 100 ms later, the patient’s trunk and shoulders follow, induced by a similar acceleration of the car seat.
- The patient’s head, with no force acting on it, remains static in space. The result is forced extension of the neck, as the shoulders travel anteriorly under the head. With this extension, the inertia of the head is overcome, and the head accelerates forward.
- The neck then acts as a lever to increase forward acceleration of the head, forcing the neck into flexion.
Frontal impact causes middle C2-3 to C4-5 and lower C6-7 and C7-T1 injury. Direct facial impact has shown a flexion motion of the upper or middle cervical spine, with extension of the lower cervical spine.
Complications of Cervical Injury
Cervical myeloradiculopathy is a complication of flexion/extension injuries in patients with underlying spondylosis. Cervical discs may become painful as part of the degenerative process, because of repetitive microtrauma or a single excessive load. Pain due to a disc injury may result from annular tears with inflammation or compression of the local nervous or vascular tissue.
Spinal cord compression after whiplash due to physiologic extension loading is not likely. However, individuals with a narrow spinal canal, most commonly due to degenerative spinal stenosis, have an increased risk of quadriparesis secondary to the spinal cord compression.
Postmortem studies have shown that ligamentous injuries are common after whiplash injuries, but disc herniation is a rare event.
Other Complications after Whiplash
Strain or tears of the anterior annulus and the alar portions of the posterior longitudinal ligament (when stretched by a bulging disc) are possible causes for discogenic pain after whiplash injury. Injuries of the zygapophysial joint found in clinical and cadaveric studies include fracture, bleeding, rupture or tear of the joint capsule, fracture of the subchondral plate, contusion of the intra-articular meniscus, and fracture of the articular surface.
Upper cervical disc protrusions as a result of cervical strain injury may result in nonspecific and shoulder pain. Motor weakness or reflex or sensory abnormalities may be limited or nonspecific. Cervical radiculopathy is more likely than are pathologic signs of upper motor neuron or spinal cord myelopathy.
MRI or computed tomography (CT) myelography are necessary for the diagnosis.
Epidemiology
Mortality/Morbidity
Mortality is rare unless severe trauma causes the cervical strain, with associated brain or spinal cord trauma, respiratory compromise, or vascular injury.
Morbidity includes cervical pain syndromes with associated symptoms. Disability in acute or chronic cervical strains is responsible for significant socioeconomic costs.
Low-energy collisions occurring at less than 6-9 mph (9.7-14.5 km/h) are thought to be unlikely to produce significant neck trauma.
Sex
Chronic neck pain, regardless of its cause, is identified in 9.5% of men and in 13.5% of women.
Age
On average, patients with a whiplash injury are in their late fourth decade.
History and Physical
The most common symptoms of cervical disorders are suboccipital cervicogenic headache and/or ongoing or motion-induced neck pain.
Other symptoms associated with cervical strain include the following:
- Neck pain
i. At the time of accident, neck pain may be minimal, with an onset of symptoms occurring during the subsequent 12-72 hours.
ii. Nonspecific neck and shoulder pain (a variety of cervical radiculopathies) may indicate an injury to a disc in the upper cervical spine. - Headache
i. Headache is a frequent symptom of cervical strain.
ii. Neck structures play a role in the pathophysiology of some headaches, but the clinical patterns have not been defined adequately.
iii. Increased muscle hardness (determined by palpation) is significantly increased in patients with chronic tension-type headaches.
iv. Facet joints and intervertebral disc damage have been implicated in the pathology of headaches due to neck injury.
v. No specific pathology on imaging or diagnostic studies has been correlated with cervicogenic headaches. - Shoulder, scapular, and/or arm pain
- Visual disturbances (eg, blurred vision, diplopia)
- Tinnitus
- Dizziness - This may result from injury to facet joints that are supplied with proprioceptive fibers; when injured, these fibers can cause confused vestibular and visual input to the brain.
- Concussion
- Neurologic symptoms - These may include weakness or heaviness in the arms, numbness, and paresthesia.
- Difficulty sleeping due to pain
- Disturbed concentration and memory
Late whiplash syndrome includes symptoms such as headache, vertigo, disturbances in concentration and memory, difficulty swallowing, and impaired vision. These cognitive impairments remain poorly understood.
Many patients with these changes have abnormal results on single-photon emission CT (SPECT) scans or P300 event-related potentials.
Bladder or bowel dysfunction - These may be symptoms of complication of myelopathy (spinal cord involvement).
Treatments
- Physical Therapy
Early rehabilitation helps to prevent chronic pain and disability. Passive modalities include the application of heat, ice, electrical stimulation, massage, myofascial release, and cervical traction. Passive modalities are often used to decrease pain or inflammation and to facilitate participation in an active rehabilitation program, which often involves stretching and strengthening. Extended use of passive modalities without a more active program is generally inappropriate.
Active treatment refers to therapeutic exercises that are aimed at improving the patient’s strength, endurance, flexibility, posture, and body mechanics. The goal is to obtain an independent home program or community fitness program at the conclusion of formal physical therapy. The typical therapy prescription is recommended 3 times per week for 4-8 weeks.
- Surgical Intervention
See the list below:
Cervical strain without myeloradiculopathy or instability is not a condition requiring surgical intervention.
Cervical myeloradiculopathy or instability, a possible complication of cervical strain, may require surgical intervention (eg, discectomy/fusion).
According to Sampath and colleagues, cervical radiculopathy has a better outcome with surgical intervention than with medical treatment. However, in clinical practice, many physicians believe that most patients respond well to nonsurgical treatment. [68]
In one study of patients with cervical spondylotic myeloradiculopathy, the short-term effects of surgery (eg, pain, weakness, sensory loss) were superior. However, at 1 year, no significant differences between surgically and nonsurgically treated groups were found.
Severe sprains of the cervical spine may result in a traumatic rupture of the intervertebral disc and ligaments, which, if not surgically treated, can lead to a significant kyphotic deformity
Medication Summary
Early and appropriate treatment with analgesics for pain relief, with anti-inflammatory agents for inflammation, with muscle relaxants for spasms, and with aids for sleep disturbance, are the mainstay pharmaceutical therapies for cervical sprain/strain injuries.
