Whiplash causes neck pain and other disorders resulting in a complex condition

The term "whiplash," used to describe an injury mechanism of sudden hyperextension (backward motion) followed by hyperflexion (forward motion) of the neck. The injury mechanism is commonly seen in sports and auto accidents. Often, no objective signs of damage to the neck are visible on cervical spine x-rays and no clinical signs of nerve damage are found and it is termed whiplash injury or neck sprain injury. A significant proportion of the injured suffer long-lasting or chronic symptoms, and some are disabled for long periods.

The most common symptoms are neck pain, neck stiffness, headache, shoulder pain, back pain, and difficulties with concentration and memory. Dizziness, buzzing in the ears, insomnia, depression, and anxiety also are reported. Since the early 1950's, more than 10,000 studies focusing on whiplash and neck sprain injuries have been published. Authors of these studies have recommended various types of initial treatment with analgesics, sedatives, antihistamines, nonsteroid anti-inflammatory drugs, antidepressive drugs, codeine, muscle relaxants, and local anesthetic injections as well as local heat and ice treatment, neck collar immobilization, ultrasound, and physiotherapy. In chronic or long-term cases, surgery and low-energy, high-frequency pulsed electromagnetic therapy have been suggested.

The main event resulting in a whiplash injury is a rearend collision of one motor vehicle with another. The stationary vehicle is struck at moderate speed, and the forward-facing victim often has no warning of the impending collision, and, therefore, is not able to brace herself or himself. Various neck injuries have been clinically documented from whiplash to the cervical spine mostly at the time of surgery. These include; interspinous ligament tears, spinous process fractures, disc rupture, endplate avulsion, C2 dens fracture, strains of the cervico-occipital joint complex, ligament flavum rupture, fracture and disruption of facet joints and over-stretching of the anterior muscles. The majority of patients with whiplash injuries do not undergo surgery, and, therefore, their soft tissue injuries remain undetected.

Although the term whiplash is widely used, it is not so much a diagnosis as a description of a process of injury. The acute trauma may be categorized as a sprain and/or strain of the neck. Whiplash associated disorder is a collection of signs and symptoms resulting from the injury and often progressing into a chronic condition causing pain and disability for months or years. Common symptoms associated with whiplash associated disorders include, but are not limited to, neck pain, headaches, dizziness, visual disturbances, impaired concentration, and sensory changes in the upper extremities. Whiplash associated disorders continue to be a burdensome health problem with serious economic consequences. One-third of persons involved in a rear-end motor vehicle collision report neck pain and other symptoms of important severity. In the United States, the economic impact of whiplash associated disorders is estimated at 4.5 billion dollars per year.

After an accident the victim has to cope with a stressful, potentially life-threatening event, in addition to the early physical complaints that result from the accident. The victim may also experience and have to cope with the fear that the complaints may lead to a chronic and invalidating disease. An active coping style is usually considered preferable in this regard and improving active coping strategies is advised as a main treatment goal. During the first weeks of neck complaints after a car accident, those who seek palliative relief of their complaints, experience fear, annoyance, anger or feel inadequate but do not share their concerns or fear with others are at risk of developing chronic or late whiplash syndrome.

Older age, female gender, higher levels of initial neck pain and headache intensity, and initial radicular (nerve) signs/symptoms are predictors of delayed recovery.

A recent study in the Journal of Rehabilitation Medicine. 2009 Apr;41(5):353-9, indicates that 5 years after whiplash injury, persistent symptoms, post-traumatic stress and depression reactions were frequently reported, together with low levels of life satisfaction and reduced social support. Both the total score of pain intensity and of whiplash related symptoms were significantly related to depression, post-traumatic stress scores and psychological factors that also include different aspects of social support many years after a whiplash event. In conclusion, this study demonstrated long-lasting symptoms and psychological consequences, reduced life satisfaction, decline in social support, and difficulties with resuming work after whiplash injury. These aspects delineate the complex nature of whiplash associated disorder and should be taken into consideration in the management.

It is unfortunate that whiplash is associated with financial gain and persons are rewarded for faking injury (malingering). This also includes doctors and lawyers (medico-legal system) who pursue unethical methods for financial gain. This is pure corruption, however, it should not reflect the nature of those who are seriously injured. Whiplash injuries can often be controversial due to lack of sensitivity of current diagnostic measures, but there is ample scientific evidence relating physical damage to structures responsible for pain and disability following whiplash injuries.

The structures of the neck which are often involved in whiplash injuries are the facet joints, spinal ligaments, intervertebral discs, vertebral arteries, dorsal root ganglia, and neck muscles.

Facet Joints

The cervical facet joints are a common source of neck pain, particularly in chronic whiplash patients. There is strong clinical evidence of facet joint related neck pain which has led to the development of medical diagnostic tests (e.g., facet blocks) and treatment procedures (e.g., radiofrequency neurotomies) that can reduce or eliminate pain for a period of time.

There are two facet joints between each pair of cervical vertebra from C2 to C7. The facet joint is a synovial joint enclosed by a thin, loose ligament known as the facet capsule. A synovial fold on the inner capsule extends between the margins of the articulating bony surfaces. The facet capsule itself lacks the stiffness to alter motion and instead follows the motions of its surrounding bony vertebrae.

The cervical facet joints have the necessary anatomical features to initiate and potentially modulate more widespread neck pain caused by facet joint syndrome. The motion of the facet joint and capsule during whiplash like impacts have been characterized in both human volunteers and cadaveric specimens. Based on documented joint motion, two mechanisms of facet joint injury have been proposed: pinching of the synovial fold and excessive strain of the capsule. It has been observed that the abnormal motion during a whiplash exposure compresses the posterior facet surfaces together, pinching the synovial fold.

Excessive facet capsule strain during whiplash has been demonstrated by numerous groups. Peak strains of 29 to 40 percent have been measured in the C6/C7 capsule of cadaveric specimens exposed to whiplash dynamics, whereas peak strains experienced during normal bending are only 6 ± 5 percent. Head-turned postures can double peak capsule strain during simulated whiplash loading. Partial ruptures of the facet capsule have been observed in both tension and shear loading of this joint along with capsule elongation during whiplash is a potential mechanism of injury in some individuals.

Their induction, persistence, and relationship to joint/capsule mechanics in painful whiplash loading supports the facet joint’s involvement in whiplash pain.

Ligaments and disc

Magentic resonance and autopsy studies of whiplash patients have documented injuries to the neck ligaments and intervertebral discs in addition to the facet joints. Ligament injuries may cause acute neck pain and lead to chronic spinal instability, abnormal muscle response patterns and decreased neck mobility.

Ligaments of the upper cervical spine have unique functional and structural anatomy, predisposing them to partial or complete rupture at low strains. Ligaments provide joint position sense during normal motion and combined with discs provide stability and absorb energy during high speed trauma. The specific function of each cervical ligament and disc in resisting whiplash loading is dependent upon its specific anatomical location, orientation, geometry, and unique mechanical properties.

Spinal ligaments and fibers encapsulating the discs can partially or completely rupture when stretched beyond their physiological limit. The whiplash related response of the cervical ligaments and discs of the neck have been quantified using a whole cadaveric cervical spine model with muscle force replication. During rear impacts with the head facing forward, dynamic strains in the anterior longitudinal ligament and annular disc fibers above physiological levels and increased joint laxity were observed. The C5/C6 disc was found to be at highest risk of injury. The disc injuries occurred at lower impact accelerations during rear impacts compared to frontal impacts.

Ligament damage may cause instability resulting in loss of motion segmet integrity which can be evaluated with flexion/extension x-rays. The AMA Guides to the Evaluation of Permanent Impairment, 5th edition, Nov. 2000, Chapter 15, pages 378-392 place a high impairment rating on loss of motion segment integrity, equating this damage as equal to a vertebra that has a compression fracture greater than 50%. This ligament instability often inteferes with normal neck posture, altering the structure of the cervical spine which may lead to chronic health problems.

Damage to the disc in whiplash injuries may cause an early onset of degenerative disc disease. An article published in Injury. 1991 Jul;22(4):307-9, indicated a significantly higher rate of disc degeneration was found in whiplash patients 10 years after the accident when compared to age matched controls.

It should be noted that a normal MRI study of the neck does not exclude the existance of clinically significant disc disease in whiplash patients suffering chronic neck, head or nerve pain. Internal Disc Disruption is a condition where the internal structure of the disc is disrupted, while the external appearance is essentially unchanged.

Vertebral Artery

The vertebral arteries supply blood to the head, brain, and neck tissues. Altered blood flow rates due to spasm and/or narrowing of vertebral arteries in whiplash patients have been associated with chronic symptoms of headache, blurred vision, tinnitus, dizziness, and vertigo. Vertebral artery injury causing inadequate perfusion of the brainstem and surrounding tissues could explain some of the whiplash-related symptoms (e.g., headache, dizziness, and vertigo).

During whiplash, especially with the head turned and side impacts, vertebral artery elongation causes a decrease in the vessel diameter and may cause vascular compromise. The magnitude, rate, and timing of vertebral artery elongation are sufficient to potentially cause vertebral artery injury.

Dorsal Root and Dorsal Root Ganglion

The dorsal (back) and ventral (front) roots come off the spinal cord and combine to form spinal nerves at each spinal level. Cell bodies of sensory nerves are contained in the dorsal root ganglion, which has been shown to be particularly sensitive to loading. Even slight compression of normal dorsal root ganglia can produce sustained electrical activity and pain. Unlike the nerves which go into the arm, the nerve roots are not enclosed by a thick protective covering, and thus they lack the mechanical strength, potentially exposing nerve roots to increased risk of injury when loaded during a whiplash injury.

Pressure gradients from blood volume changes between the inside and outside of the spinal canal during rapid whiplash induced motions can directly load the spinal ganglia and nerve roots, potentially leading to whiplash related symptoms.

Direct injury to cell bodies within the dorsal root ganglion could thus explain many of the typical whiplash symptoms (e.g., neck pain, cervicogenic (neck related headaches), vertigo, vision disturbance, and neurological symptoms in the upper extremities). Generalized hypersensitivity to pressure acutely and chronically and decreased thermal pain thresholds in the skin over the cervical spine can be explained by impaired local sensory processing. Increased sensitivity to pain (hyperalgesia) and larger areas of referred pain are also reported for whiplash patients.

Deformation of the nerve roots themselves is another potential mechanism for producing persistent neck pain. The bony openings called intervertebral foramina change shape and decrease their diameter during extreme neck motions which can compress the nerve root within the foramina during whiplash motions. It has been reported that a 20 percent decrease in area for the C4-C7 intervertebral foramina of cervical spines in extension and the intervertebral foramen at C5/C6 are narrowed by as much as 1.8 mm during simulated rear impacts. This dynamic narrowing of the foramen during whiplash may compress the nerve roots and ganglia in the lower cervical spine, particularly in individuals with congenitally narrow foramen or those with osteophytes from degeneration.

Complaints of neck pain and involvement in one or both arms is often called a cervico-brachial syndrome. Symptoms described as sharp and shooting often result from involvement of the dorsal root ganglion, while irritation of the nerve root often is described as slow in onset and aching in nature.

Findings with nerve irritation is often found when side bending the head towards the painful side and relief when the painful arm is raised above the head. Neck traction is sometimes used to reduce mechanical irritation of the nerve root or dorsal root ganglion.

Muscle

Muscle or myofascial pain is a common symptom reported by whiplash patients and for chronic whiplash pain, muscles may play an indirect role in modulating pain caused by injuries to other structures.

Muscles comprise the majority of the neck’s volume and the superficial muscles, such as sternocleidomastoid or trapezius, are often implicated in the pain and tenderness associated with whiplash injury. These superficial muscles attach to the skull, shoulder girdle, and nuchal ligament but do not generally attach directly to the cervical vertebrae. Deeper muscles attach on multiple cervical vertebrae. The deepest neck muscles, the multifidus muscles, insert directly on the facet joint capsule of cervical vertebrae and may be relevant to injury of the capsular ligaments. Most neck muscles have complex architecture, with extensive internal tendon and the presence and arrangement of the internal tendon may be related to musculotendinous pain.

The direct mechanism of neck muscle injury occurs from eccentric contractions (imposed lengthening during active contraction). Computer simulations using experimental kinematics of human subjects exposured to whiplash collisions have shown that both front and back neck muscles experience active lengthening during rear impacts. For simulated impacts with a speed change of 8 km/h, peak muscle fascicle strains averaged about 7 percent (max. 15%) in the sternocleidomastoid and 21 percent (max. 50%) in the posterior muscles such as semispinalis capitis. These strains exceeded those shown to cause muscle injury (5–20%) in laboratory studies, thus, acute neck muscle injury may occur during rearend impacts.

Neck muscles potentially interact with other anatomical sites of whiplash injury in at least three ways: (1) neck muscles attach directly to the facet capsule, which has been implicated in chronic pain following whiplash; (2) neck muscle activation indirectly affects the loads and strains in other anatomical structures; and (3) altered neuromuscular control may contribute to chronic pain from elevated and inappropriate muscle activation.

Neck muscle activation also affects spinal tissue loads by increasing intervertebral compression and altering normal motion. Because neck muscles are oriented primarily up and down, their activation produces axial compression of the cervical spine, increasing loads on the intervertebral disc and facet joints. Muscle activation also affects the motion response of the head and neck, thus load and strain thresholds for injury may be exceeded in other structures such as ligaments, discs and facet joints.

The interaction between muscles and the nervous system (neuromuscular control) may be also related to chronic pain. An inability to relax after exercise and excessive activation are associated with neck pain, and relaxing selected neck muscles with botulinum toxin improves range of motion and reduces pain in these patients. This suggests that pain and increased muscle activity may reinforce one another. It remains unclear whether muscle dysfunction is a cause (leading to damage of other anatomical structures) or effect (due to disuse or pain avoidance) of pain or merely an associated correlation.

A recent MRI investigation in Spine 2006;31:E847–E855, has demonstrated marked structural changes to neck muscles in persons with chronic whiplash. This type of fatty degeneration of the neck muscles are postulated to be the result of local structural damage, a nerve injury, or a generalized disuse phenomenon.

Some gentle neck exercises may be beneficial to help prevent chronic whiplash.

Some general advice:

Findings in the journal, PLoS Med. 2008 May 13;5(5):e105, indicate that those with the lowest expectations for recovery after their whiplash injury will have the poorest recovery, and those with the highest expectations will have the best recovery. They also suggest that a patient's expectations about getting better are as important as his or her physical symptoms. The authors say that the more we can influence patients to believe they will make a full recovery, the better chance they will have to recover completely. This means that it may be beneficial for healthcare providers to give support and/or education to patients with whiplash associated disorders that increases their positive feelings toward recovery.

After a whiplash injury and professional clinical assessment has ruled out any fractures, serious injuries or complicating factors:

• Accept there has been an injury to the neck, but there has been no serious damage. After a whiplash injury the neck is simply not moving and working properly. The muscles and joints have been affected but they have a natural ability to repair and restore, which is helped by activity.



• It should improve rapidly with an active approach; there is no reason why long term disability should ensue. Although symptoms may persist for a while, the acute pain will improve within a few days or weeks, certainly enough to get on with life.



• Recognize other symptoms: Headache, arm pain, jaw pain, and dizziness are common and not a reason for concern.



• Use simple analgesia; it’s an aid to increasing early activity. Try to find a way to relax and don’t worry.



• Prolonged inactivity is unhelpful: Avoiding daily activities slows recovery. Some activities may involve some pain, but hurt is not the same as harm.



• Staying as active as possible is important: Keep moving, don’t stay in one position too long, move about before you stiffen up, and don’t completely avoid things. Most daily activities and early return to work are helpful.



• Exercises are helpful: Simple neck and shoulder exercises are safe and effective—stretching, strengthening and coordination exercises should be done regularly each day; initial soreness is not a reason for concern.



• Psychological factors (notably distress and fear) are risk factors for developing a chronic problem: Don’t worry and don’t be frightened of movement or pain activity and a positive approach are the keys to avoiding long term problems. Don’t be an avoider.

Lastly, you should make sure your head rests (head restraints) are adjusted properly. Properly adjusted head rests can significantly reduce the level of injury in a whiplash car crash. If you have sustained a whiplash injury, don't think it can't happen again. Protect your neck by using the right head rest adjustment and because many head rests are inadequate, you should use a car seat head support. It is made by Add On Head Rest and has been tested in car crashes to reduce the severity of whiplash injury. I have been using one for years and highly recommend it along with many other knowledgeable health care professionals.