INTRODUCTION

The term “whiplash” is given to the acceleration-deceleration mechanism of energy transfer to the neck and head at impact. It may result from rear-end or side-impact motor vehicle collisions, but can also occur during sport (horse riding, diving, snowboarding) and other mishaps. The impact may result in physical injury (bony and/or soft-tissue injuries) and/or psychological trauma (distress), which in turn can lead to a variety of clinical manifestations, including neck pain, neck stiffness, headache, dizziness, paresthesias, and cognitive difficulties such as memory loss. These clinical manifestations are known as whiplash-associated disorders (WAD) (Spitzer et al., 1995).

EPIDEMIOLOGY & ECONOMICS

1. Whiplash is the most common injury associated with motor vehicle accidents and a major cause of disability and litigation (Ritchie, Hendrikz, Kenardy, & Sterling, 2013).
2. The Incidence of whiplash injury and WAD is dependent of the country or the part of the world. Epidemiological data on the incidence of whiplash are mainly derived from insurance claim numbers. Therefore, the reported annual incidence of whiplash varies widely between countries and continents. For example, In New Zealand, the annual incidence of whiplash injury is 16 per 100.000 inhabitants, in Canada 70 per 100.000 inhabitants (Spitzer et al., 1995), in Australia 106 per 100.000 inhabitants (Miles, Maimaris, Finlay, & Barnes, 1988), in the Netherlands 188-325 per 100.000 inhabitants (Wismans KSHM, 1994), in Sweden 235 per 100.000 inhabitants (Styrke, Stalnacke, Bylund, Sojka, & Bjornstig, 2012). Incidence numbers of whiplash injury in Belgium have not been found, however, in 2016, Belgium counted 40.096 motor vehicle accidents and in total 51.827 traffic casualties of which 47.087 sustained minor injury, 4.103 severe injury, and 637 people lost their life. (Statistics Belgium, 2017).
3. Some evidence suggests that the incidence of whiplash injury is still rising as the result of increases in availability and use of cars worldwide. During the last 30 years, the cumulative incidence of WAD resulting from motor vehicle collisions has risen to >300/100.000 people in North America and Western Europe (Holm et al., 2008).
4. Those with whiplash injury have a high chance of developing persistent symptoms. Approximately 50% of those with whiplash injury develop persistent symptoms with moderate to severe intensity that will significantly impact their lives (Campbell, Smith, McGregor, & Sterling, 2018; Carroll et al., 2009; Steven J. Kamper, Trudy J. Rebbeck, Christopher G. Maher, James H. McAuley, & Michele Sterling, 2008; Williamson, Williams, Gates, & Lamb, 2008).
5. The most consistent predictors of poor recovery are moderate to high initial levels of pain and/or disability. Collision related factors are not predictive of poor recovery as someone most often would expect (P. Sarrami, Armstrong, Naylor, & Harris, 2017).
6. Most recovery occurs within the first 3 months, after which time the condition tends to plateau (S. J. Kamper, T. J. Rebbeck, C. G. Maher, J. H. McAuley, & M. Sterling, 2008).
7. Costs associated with the condition are substantial. Annual costs are reported to rise up to 10 billion euros per year in European society due to continuing treatment costs, productivity loss, work absenteeism, and compulsory third party insurance claims (European_Transport_Safety_Council. Reining in whiplash - better protection for Europe's car occupants, 2007).
8. The role of compensation-related factors on outcome is controversial. In several countries such as Lithuania and Greece, where there is no compensation culture, the development of chronic pain after whiplash injury is rare and claimants recover faster (Partheni et al., 2000, Schrader et al., 1996). However, an expanding international base of research tends to suggest that compensation may have some, but not necessarily a major effect on outcome (Spearing & Connelly, 2011; Spearing, Connelly, Gargett, & Sterling, 2012; Spearing, Connelly, Nghiem, & Pobereskin, 2012; Spearing, Gyrd-Hansen, Pobereskin, Rowell, & Connelly, 2012).

PATHOPHYSIOLOGY

1. After 30-plus years of research, the exact pathophysiology of whiplash is still not entirely clear. People suffering from “WAD” are defined as having been exposed to similar types of trauma or sometimes even similar mode of impact, rather than as having a certain type of lesion, injury or set of symptoms.
2. When looking at pathophysiologic mechanisms of WAD, evidencesuggests both structural lesions and effects on sensory and motor function:

• Evidence of lesions to cervical spine structures such as the intervertebral discs, cervical ligaments and muscles, and particularly the zygapophyseal joints (Persson, Sörensen, & Gerdle, 2016).
• Evidence of sensory disturbances indicative of augmented central pain processing mechanisms (Van Oosterwijck, Nijs, Meeus, & Paul, 2013).
• Evidence of disturbed muscle function in the form of morphological muscle changes and disturbances in movement and neuromotor control (De Pauw et al., 2016; Falla, Bilenkij, & Jull, 2004; Ulbrich et al., 2011).
• Evidence of disturbed sensorimotor control, including kinesthetic deficits, loss of balance, and loss of eye movement control. These features seem to be associated with symptoms of dizziness (J. Treleaven, Peterson, Ludvigsson, Kammerlind, & Peolsson, 2016).
• Evidence of concomitant mild brain injury

1. To date, knowledge of pathophysiological parameters that influence the mechanism(s) behind prolonged WAD are insufficient, and it is not known whether or not changes can be restored by rehabilitation (Peolsson et al., 2019).

CLINICAL FEATURES

1. The onset of symptoms may occur immediately after the accident or may be delayed for up to 2-3 days (Delfini et al., 1999).
2. The predominant symptom is neck pain, but headache, back pain, and shoulder/arm pain can also be present next to other common symptoms, including dizziness, visual and auditory disturbances, temporomandibular joint pain, photophobia, fatigue, and cognitive difficulties (Binder, 2007; Julia Treleaven, 2017).
3. Early post-traumatic stress symptoms and negative expectations of recovery are emerging as important psychological features in some patients and are positively associated with ongoing neck pain and disability (Pooria Sarrami, Armstrong, Naylor, & Harris, 2016; Sterling, Hendrikz, & Kenardy, 2011).
4. The clinical presentation of patients with WAD can be complex (Anstey, Kongsted, Kamper, & Hancock, 2016). Approximately 20 to 30% of those injured will display a complex presentation comprising:

• Sensory disturbances such as allodynia and widespread hyperalgesia in the neck region, but also at remote sites such as the lower limbs.
• Cold hyperalgesia, which seems important as it is associated with poor recovery and with non-responsiveness to standard physical treatment approaches such as exercise.
• Spinal cord hyperexcitability via heightened flexor withdrawal responses.
• Marked loss of neck movement.
• Motor control deficits, including altered patterns of muscle recruitment in the neck and shoulder girdles.
• Fatty infiltration of the neck flexor and extensor muscles, identified on magnetic resonance imaging (MRI).

DIAGNOSTIC CRITERIA

1. There is no diagnostic or lab test for whiplash. The diagnosis is based on signs and symptoms reported by the patient, which may or may not be reliable. A good diagnosis requires proper history taking, inspection, and careful functional examination, including a neurological evaluation.
2. Scans are in most cases not recommended or useful. X-rays and other imaging techniques (CT-scan, MRI) are not useful in the majority of cases to identify a structural lesion (WAD grades I and II) and are only recommended for select cases. Current clinical guidelines recommend that practitioners use the Canadian C-Spine Rule (Michaleff, Maher, Verhagen, Rebbeck, & Lin, 2012) to determine whether X-ray of the cervical spine is required for diagnosis of fracture or dislocation and to avoid unnecessary exposure to X-rays ("State Insurance Regulatory Authority: Guidelines for the management of acute whiplash-associated disorders – for health professionals. Sydney: third edition.," 2014).
3. For the moment, The Quebec Task Force Classification is still the most commonly used and recognized classification system. However, it is nonspecific, particularly regarding the WAD Grade II classification. It fails to take into account recently identified motor, sensory, and psychological features.

Table 1 Classification of WAD (NICE. Neck pain – whiplash injury; State Insurance Regulatory Authority: Guidelines for the management of acute whiplash-associated disorders – for health professionals. Sydney: third edition.," 2014)

TREATMENT

Whiplash injuries are quite difficult to treat because of interactions of various factors such as patient psychology, socioeconomic factors, legal issues, and physical health. The absence of radiological evidence of injury in the symptomatic group further complicates the treatment process for this condition.

1. The interventions with the strongest evidence of treatment efficacy for acute whiplash are (Center of Trauma and Injury Recovery, 2008; "State Insurance Regulatory Authority: Guidelines for the management of acute whiplash-associated disorders – for health professionals. Sydney: third edition.," 2014):

• Reassurance, education, and instructions to maintain activity levels.
• Exercise, including prescribed functional exercises as well as range-of-motion exercises and muscle re-education.

The interventions with the strongest evidence of treatment efficacy for chronic whiplash are (Center of Trauma and Injury Recovery, 2008):

• Reassurance, education, and instructions to maintain activity levels.
• Exercise, including prescribed functional exercises as well as range-of-motion exercises and muscle re-education.
• Psychological treatments, which may be effective in conjunction with rehabilitation.
• Radiofrequency neurotomy in selected cases.

1. The wearing of collars is not recommended in patients with acute WAD and may delay recovery. Active treatment is more beneficial ("State Insurance Regulatory Authority: Guidelines for the management of acute whiplash-associated disorders – for health professionals. Sydney: third edition.," 2014).

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Ward Willaert

Ward Willaert is a doctoral researcher at the Vrije Universiteit Brussel (Brussels, Belgium) and Ghent university (Ghent, Belgium). He is a member of the Pain in Motion research group and his research and clinical interest goes out to chronic "unexplained" pain, associated disorders, diagnosis and treatment of (chronic) pain. He has a special interest in whiplash associated disorders and the central nervous system.

2020Pain in Motion

References and further reading:

Anstey, R., Kongsted, A., Kamper, S., & Hancock, M. J. (2016). Are People With Whiplash-Associated Neck Pain Different From People With Nonspecific Neck Pain J Orthop Sports Phys Ther, 46(10), 894-901. doi:10.2519/jospt.2016.6588

Binder, A. (2007). The diagnosis and treatment of nonspecific neck pain and whiplash. Europa Medicophysica, 43, 79-89.

Campbell, L., Smith, A., McGregor, L., & Sterling, M. (2018). Psychological Factors and the Development of Chronic Whiplash-associated Disorder(s): A Systematic Review. Clin J Pain, 34(8), 755-768. doi:10.1097/AJP.0000000000000597

Carroll, L. J., Holm, L. W., Hogg-Johnson, S., Cote, P., Cassidy, J. D., Haldeman, S., Guzman, J. (2009). Course and prognostic factors for neck pain in whiplash-associated disorders (WAD): results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders. J Manipulative Physiol Ther, 32(2 Suppl), S97-S107. doi:10.1016/j.jmpt.2008.11.014

De Pauw, R., Coppieters, I., Kregel, J., De Meulemeester, K., Danneels, L., & Cagnie, B. (2016). Does muscle morphology change in chronic neck pain patients? A systematic review. doi:10.1016/j.math.2015.11.006

Delfini, R., Dorizzi, A., Facchinetti, G., Faccioli, F., Galzio, R., & Vangelista, T. (1999). Delayed post-traumatic cervical instability. Surg Neurol, 51(6), 588-594; discussion 594-585. doi:10.1016/s0090-3019(99)00020-8

European_Transport_Safety_Council. [2017-03-13]. Reining in whiplash - better protection for Europe's car occupants. (2007).

Falla, D., Bilenkij, G., & Jull, G. (2004). Patients with chronic neck pain demonstrate altered patterns of muscle activation during performance of a functional upper limb task. Spine (Phila Pa 1976), 29(13), 1436-1440.

Holm, L. W., Carroll, L. J., Cassidy, J. D., Hogg-Johnson, S., Cote, P., Guzman, J., . . . Its Associated, D. (2008). The burden and determinants of neck pain in whiplash-associated disorders after traffic collisions: results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders. Spine (Phila Pa 1976), 33(4 Suppl), S52-59. doi:10.1097/BRS.0b013e3181643ece

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Peolsson, A., Karlsson, A., Ghafouri, B., Ebbers, T., Engstrom, M., Jonsson, M., Peterson, G. (2019). Pathophysiology behind prolonged whiplash associated disorders: study protocol for an experimental study. BMC Musculoskelet Disord, 20(1), 51. doi:10.1186/s12891-019-2433-3

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Sarrami, P., Armstrong, E., Naylor, J. M., & Harris, I. A. (2017). Factors predicting outcome in whiplash injury: a systematic meta-review of prognostic factors. J Orthop Traumatol, 18(1), 9-16. doi:10.1007/s10195-016-0431-x

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Spearing, N. M., Gyrd-Hansen, D., Pobereskin, L. H., Rowell, D. S., & Connelly, L. B. (2012). Are people who claim compensation "cured by a verdict"? A longitudinal study of health outcomes after whiplash. J Law Med, 20(1), 82-92.

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