Whiplash injuries can cause many different symptoms beyond the usual neck pain that most people associate it with. Pain, dizziness, headaches, fatigue are other possible symptoms. Depending on the type and velocity of a collision, other body parts can get injured such as the midback, hips, and even the shoulder. According to one study published in the Journcal of Orthopedic Surgery, out of 220 patients with whiplash, 26% suffered shoulder symptoms- and 5% suffered an impingement syndrome.
An impingement syndrome arises because of referred pain from the neck and nerve injury to the muscles that stabilize the shoulder. These shoulder muscles include the rotator cuff muscles. The rotator cuff is formed by the tendons of 4 muscles: teres minor, subscapularis, supraspinatus and infraspinatus. Direct trauma can also occur from the pressure supplied by a seatbelt during a front end collision. Cartilage damage and muscle sprains can occut. Furthermore, the acromium can affect the tendons of the rotator cuff muscles and other soft tissues just under this bone. Finally, there are bursa (fluid filled sacs) surrounding the shoulder which can become swelled, causing pain at night. The pressure within the rotator cuff muscles increases, which results in compression and loss of blood flow in the smaller blood vessels. This reduction of blood flow causes the muscle tissue begins to fray like a rope. Activities such as reaching up behind the back and reaching up overhead to put on a shirt can cause pain.
Sometimes whiplash sufferers have shoulder pain which is thought to stem from the neck; therefore an impingement syndrome can often be overlooked. If these muscles are injured for a long period of time, the muscle can actually tear in two, resulting in a rotator cuff tear. This creates a weakness in the shoulder and it is difficult to complete simple tasks as elevating ones shoulder. This can delay proper treatment, thus causing chronic pain, and possibly disability.
You should have a proper history, consultation and phsyical examination to determine if you have an impingement syndrome. One diagnostic tool is via a shoulder MRI. It can show if the labrum (cartilage surrounding the bone) can break way causing pain. Inflammation of the surrounding tendons can also occur.
So when you have whiplash and shoulder pain- think of other things that can be causing the pain in your shoulder.
Source: Subacromial Impingement in Patients with whiplash injury to the cervical spine; Journal of Orthopedic Surgery 2008;3:25, Abbassian A. Giddins GE.