Neck Pain in Adults _________________________________________________________________________
Acute Whiplash-Associated Disorders Recovery rates from WAD have been unchanged for decades, with 50% of patients experiencing ongoing pain and disability [15]. Following acute whiplash injury, recovery is slow for pain intensity outcomes, which usually require six months or longer to decrease 20%. Recovery is no better for disability outcomes, with average scores failing to reach 20% improvement by 12 months [29]. Following acute traumatic neck pain (including WAD), patients follow one of three likely trajectories for pain and disability [29]: • Mild problems with rapid recovery (45% of patients, depending on outcome) • Moderate problems with incomplete recovery (40%) • Severe problems with little or no recovery (15%) Regardless of outcome, recovery is most rapid in the first 6 to 12 post-injury weeks, with considerable slowing after that and little recovery after 12 months [30]. Prognostic Factors in Acute WAD During acute or subacute WAD, risk factors for persistent problems include [29]: • High pain intensity • High self-reported disability (as determined by Neck Disability Index [NDI] score) • High post-traumatic stress symptoms • Strong catastrophic beliefs • Cold hyperalgesia A meta-review of factors associated with long-term pain and disability after whiplash injury identified post-injury pain and disability, whiplash grade, and cold hyperalgesia as the strongest prognostic factors [31]. Factors unrelated to prognosis include those related to the collision (e.g., impact direction, stationary versus moving, seating position in car). Post-injury imaging findings or motor dysfunction has very weak association with pain/disability prognosis [29; 31]. Compensation and early healthcare use were weakly positive prognostic factors, but equally plausible is reverse causality, whereby poor outcome is the cause of healthcare use and compensation-seeking [31]. Patients suffering from post-motor vehicle collision WAD often litigate to gain more comprehensive medical treatment and monetary compensation for their injury. A long-standing concern of treating physicians is that patients with whiplash may have barriers to recovery—believing they must remain “injured” to collect a settlement [16]. Compensation has been associated with incidence and prognosis, but literature indicates that litigation does not correlate with persistence of pain [32; 33].
The annual rate for acute whiplash symptoms is 1 to 6 cases per 1,000 population, and an estimated 1% of adults have chronic whiplash pain. In data from nine U.S. states, 45% of patients with chronic neck pain attributed their pain to a motor vehicle collision [16; 21]. Women show higher rates of WAD, possibly due to less well- developed neck muscles than men. Pre-existing cervical spine pathology predisposes to spinal cord damage in whiplash injuries [19]. Head restraints have greatly reduced whiplash injury rates following rear-end collisions, but they increase whiplash injury risk when poorly fitted [16; 19]. Cervical Radiculopathy Cervical radiculopathy is cervical spine nerve root dysfunction that causes radiating neck or upper extremity pain or sensory abnormalities [22]. New cases are higher in men (107.3 per 100,000) than women (63.5 per 100,000) annually. Persons 50 to 54 years of age have the highest incidence by age. Overall, the prevalence is 3.5 cases per 1,000 population [22; 23; 24]. Risk factors include manual labor requiring lifting of more than 25 pounds, smoking, operating vibrating equipment, and previous spinal radiculopathy. Over-exertion or trauma antecedents are reported by 15% of patients with cervical radiculopathy [22; 24].
CLINICAL COURSE AND PROGNOSIS Acute Nonspecific (Idiopathic) Neck Pain
Outcomes for acute idiopathic neck pain are surprisingly poor. Resolution is often incomplete, and prognosis is markedly worse than commonly believed. Statistical pooling of published outcomes showed an average pain severity score (on a 0–100 scale) of 64 at onset, decreasing to 35 at 6.5 weeks, but increasing by 12 months to 42. Disability declined from an average score (0–100) of 30 at onset to 17 by 6.5 weeks, without further improvement at 12 months [25]. After the first 6.5 weeks, no further reduction in neck pain was found. The initial decreases in pain (45%) and disability (43%) are worthwhile to some patients, but the severity of persistent pain (35–42/100 up to one year) is sufficient to interfere with functioning and quality of life. Compared with low back pain one year after onset, neck pain intensity is twice as high and disability is comparable [25; 26; 27]. A comparison of 2,578 patients with WAD or nonspecific neck pain found substantially greater presence of dizziness and memory impairment at initial assessment. Between-group differences in pain and disability increased significantly over 12 months; patients with WAD had an average 2 points greater pain (on a 0–10 scale) and 17% more disability than those with nonspecific neck pain [28].
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