Chronic whiplash injury means neck pain persisting for greater than 12 weeks, no matter the form of conservative care. Chronic whiplash injury is common in personal injury medicine, due in part to the fact that chronic whiplash itself is a common injury in motor vehicle and other accidents. Unfortunately, the accurate and appropriate care of the chronic whiplash injury patient is not as common as the condition itself.
MRI
Persistent symptoms greater than 4 weeks is an indication for an MRI. Spine medical societies, like the North American Spine Society, all agree on this. An MRI is essential for ruling out nefarious causes of pain. An MRI is also necessary for ruling out a cervical disc herniation, the cause of chronic neck injury after whiplash in about 20% of cases. Obtaining an MRI in a timely manner is important. Firstly, detecting a large herniation with spinal cord compression has an impact on chiropractic manipulation; most experts would recommend against it in this setting. Secondly, in a patient with severe symptoms, an MRI might warrant an epidural injection before further therapy. For these reasons it is medically unreasonable to hold off on an MRI beyond 4 weeks in most cases.
Epidural injections
If the MRI shows a protruding disc, (a type of disc herniation) then an epidural is indicated. However, most MRI sequences cannot distinguish between normal wear and tear (degeneration) and a disc protrusion. To make sure the appropriate diagnosis is made, a Gradient Echo sequence should be added to the MRI examination. Gradient Echo will distinguish between a herniation and wear and tear in most cases. If there is no herniation, an epidural injection is not usually necessary.
In the whiplash patient with a herniation on MR, multiple epidural injections are usually not required. The patient should have one epidural and should be re-evaluated after a reasonable amount of time prior to repeating the epidural. A second injection should not be had unless there is substantial benefit from the first one. Every major spine medical society has reiterated this in their guidelines statements. Under no circumstances should the patient automatically be scheduled for a “series” of injections. The performance of serial epidural injections is an urban myth not supported by any science or medical guidelines.
Facet blocks, injections and rhizotomy
If the appropriate MRI, with Gradient Echo imaging, shows no disc herniation it may still be appropriate to consider interventional therapy. However, rather than an epidural injection, the intervention should target the facet joint. This is because the facet joint is the cause of neck pain in about 80% of chronic whiplash injury cases. If one intends to make a diagnosis to plan future treatment, then a medial branch block is performed. Here an anesthetic is injected into a microscopic nerve that senses pain at the joint. If the pain goes away the test is positive, and the painful joint has been identified. If no future care is contemplated, and the aim is only to provide relief, then the suspected joint is injected with a combination of steroid and anesthetic. This is called a facet joint injection.
When the injured facet joint is the C2/3 joint, a nerve called the third occipital nerve is injected. This procedure is like a medial branch injection but a bit more complicated due to anatomic concerns. C2/3 is the most common cause of upper neck pain after whiplash. When physicians inject C3/4 or C4/5, one must be aware that they may be injecting a less commonly affected joint in the hopes of avoiding a more complex procedure.
When third occipital nerve blocks or medial branch blocks are positive, radiofrequency neurotomy is the treatment of choice. It has a high effectiveness, is minimally invasive, is safe and there is essentially no recovery time. In this procedure an electrode is placed along the pain sensing facet nerve. Radiofrequency energy is applied. The energy coagulates the nerve, relieving the sensation of pain. The procedure remains among the most well studied among spinal surgeries and interventions.
Spinal surgery
Sometimes surgery is required for a whiplash injury. When a large disc herniation has caused spinal cord compression and there is spinal cord dysfunction, surgery is indicated at any time. The aim of surgery is decompression of the spinal cord. Commonly, this is accomplished with either cervical disc replacement or cervical fusion. However, one must must be aware of the consequences of standalone cervical disc replacement in the setting of whiplash. Because the facet joint is usually injured when the disc is injured, maintenance of motion of the neck after disc replacement will result in persistent pain, something that does not occur with fusion because there is no residual motion. To avoid this, radiofrequency rhizotomy of the facet joint at the same level should be undertaken.
In a discreet herniation, a small anterior cervical discectomy without fusion can be performed. This is usually done endoscopically. Again, the patient may require rhizotomy for concomitant facet injury.
While cervical fusion can effectively treat facet pain by restricting motion at the injured segment, (the facets don’t move so they don’t hurt) it should be avoided when only treating facet pain because it is inappropriate for this indication. Radiofrequency rhizotomy is a far less expensive and much safer treatment. While the procedure needs to be repeated in about one third of patients, most would agree that this is a reasonable trade off compared to the unnecessary removal of a normal and asymptomatic disc and the unnecessary placement of hardware into the neck.
Recently, endoscopic facet debridement has emerged as a therapy for severe, chronic and unresponsive cervical facet pain. This may be an option for patients with recurrent pain after radiofrequency rhizotomy or severe facet pain.
Earlier we discussed utilizing an MRI with Gradient Echo imaging in chronic whiplash patients. Ordering the appropriate MRI in whiplash is essential. The confusion between normal degenerative changes and a disc protrusion brought on by standard MRI’s will often lead to the recommendation of a cervical fusion when the discs are in fact only degenerated. This becomes a set up for the scenario discussed above; cervical fusion in a patient that only has a facet injury.
Gradient Echo MRI will also avoid another major pitfall in the spinal surgery of the chronic whiplash patient; the avoidance of unnecessary second or even third level surgery. Gradient Echo MRI can both rule in and rule out a disc herniation. In a patient with multiple abnormalities Gradient Echo MRI can diagnose a herniated disc at one level and degenerative changes at other levels. This distinction should hopefully lead the treating surgeon to avoid a second level surgery simply because of a bony spur or mild/moderate stenosis (abnormal narrowing). This unnecessary adjacent level surgery adds to the risk of the patient without any benefit whatsoever.
The high likelihood of a disc herniation and a concomitant cervical facet injury at a second level is a common occurrence that is often overlooked, resulting in a still suffering patient. It is common for a C2/3 facet and a C5/6 disc herniation to co-exist. While C5/6 is commonly treated by disc replacement or fusion C2/3 is not. As a result, the C2/3 injury is not addressed by the surgeon. In these cases, the patient should be referred to a spine interventionist competent in C2/3 blocks and rhizotomy. Given the complexity of the C2/3 anatomy this is sometimes easier said than done.
Conclusion
Whiplash injury can be elusive to diagnose and the treatment can be very confusing. It is common for patients to receive an unnecessary number of injections as well as the wrong type of injections. Surgery can leave patients with persistent symptoms because either a disc replacement was used without treating the facet joint injury or an upper cervical facet injury was left untreated after a large lower level surgery. Worse yet, the wrong type of MRI can lead to surgery by wrongly diagnosing a disc protrusion. When surgery is indicated a multidisciplinary approach will avoid unnecessary surgery and address residual symptoms.
Jim Parsons, MD
The views expressed are the personal views of the author and do not represent the views of The Brain, Spine and Joint Group, its managers, affiliates, partners, employees or its clients. Furthermore, the information provided by the author is not intended to be expert or legal advice.
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