A "Negative" MRI and Spine Pain - A Common Culprit Following Injury

"How can I be in pain but my MRI didn't show anything?"

Imagine you are driving along a busy stretch of road on your morning commute and you are approaching a red light. As you brake, you check your rear-view mirror and see a car traveling too fast to possibly stop in time before hitting you. Before you know it, in the blink of an eye, you've been rear-ended. Some individuals may have pain instantly following their accident while others have a slower and more gradual onset. After being evaluated by your healthcare provider, they may elect to order advanced imaging such as an MRI of your spine to assess for many things including the disc herniations, soft tissue injuries, and evident signs of edema/inflammation. After laying in the MRI tube with some headphones on listening to smooth jazz and the sounds of magnets pulse over and over for about 25 minutes, your doctor's office calls you to schedule your review of findings visit. While going over your imaging and report, the doctor says, "Well, your MRI came back negative... I don't see any findings from the MRI directly that could be causing your pain." At this point, you're probably thinking to yourself in their office, "How can I be in pain but my MRI didn't show anything?" Patients that end up in this situation often feel confused and discouraged in their care plans, but they shouldn't fret; there is still more work-up that can be done in these situations.

A Common Culprit in Spine Pain

One routine pain generator I see in my practice during these scenarios is the spinal facet joint. The facet joints located in the back of the spine essentially link the vertebrae together and allow for the spine to bend and twist to a degree. These stacked capsuled joints span across our cervical (neck), thoracic (mid-back) and lumbar (low-back) spine. The facet joints also contain nerves (medial branch nerves) which relay pain signals from the facet to the brain.

Pain from the facet joint can be local (axial pain) to just the area of the spine where it is affected or can be felt in other places (referred pain) as well. Most individuals report the pain to be stiff, achy, or sharp in nature and in some circumstances can cause headaches in people with cervical facet joints. Excess stress to the facet joints can also arise from decreased disc height in a degenerated spinal segment and thus create inflammation/irritation. In terms of injury, strain on the facet joint is highest when the spine is in terminal (full) extension such as what is experienced in whiplash injuries. Electrophysiological studies have shown when the facet joint is loaded/compressed in the cervical spine that nerves are activated within the joint capsule to be hyperexcitable, which can be a mediator of pain production. Another study has concluded that facet joints may be injured at as low as 3.5 g while capsular ligamentous damage may be seen at higher accelerations.

Spine Pain and Facet Joints Don't Always Come Together on MRI

Although the facet joint may be a pain generator for many, it doesn't always show up on an MRI with clear definitive findings. During the history of present illness when consulting with a patient, vital information can be obtained to determine if advanced imaging such as an MRI is indicated on that initial or subsequent visit. Such details can include the presence of red flags like recent weight loss with spine pain, suspected fractures/instability, possible infection, or recent trauma like a motor vehicle accident, sports injury or slip and fall.

It is imperative that all spine care providers (chiropractors, physiatrists, orthopedic/neurosurgeons, etc) have a fundamental understanding of interpreting the spinal MRI studies that they order. There can be significant variability in spinal MRI radiology reports depending on who is reading the images; simply put, one reason why a patient may have a "negative" MRI study is that it was misread or underread by the radiologist and ordering provider. One study showed that there was a miss rate?of 43.6% in reporting lumbar disc pathology on radiology reports amongst 10 different MRI facilities on the same patient. The authors of this study concluded that:

"Where a patient obtains his or her MRI examination and which radiologist interprets the examination may have a direct impact on radiological diagnosis, subsequent choice of treatment, and clinical outcome."

Another study showed that?radiology reports did not clearly describe lumbar disc herniation morphology in 42.2% of 214 cases reviewed. Being credentialed in spinal MRI and reading thousands of studies in my career from across the world triaging spine care cases, I find these numbers to be on par with what I have clinically seen in terms of underreported spinal MRI radiology reports. I personally read my ordered spinal MRI studies and create my own interpretation prior to the reading radiologist's formal report being drafted. Partnering with a highly skilled and accessible radiologist is essential when reading imaging studies on a patient-centric medical team. Effectively assessing a spinal MRI is a critical step in ruling in or ruling out facetogenic pain.

The most common facet joint findings I see on spinal MRI include facet hypertrophy (enlarged facet joints usually due to degenerative changes), facet effusion (fluid within the facet which can be indicative of instability, degeneration or inflammation), thickened ligamenta flava bordering the facets, and occasional synovial cysts. Below is a demonstration of a T2 axial (tree-trunk type cut) MRI sliced through the L4-5 disc space. To orient yourself with what you are seeing, the bottom of the image is the patient's back while the right of the image is actual the patient's left side and vice versa. When interpreting an axial spinal MRI slice, we are actually looking at the person from the bottom of their feet towards their head. This MRI demonstrates nicely that the purple colored-coded facets are enlarged (or hypertrophied) while the patient's left facet has a white appearance within the joint; this hyperintense (bright) signal indicates facet effusion (fluid). However, when an MRI is negative for any of these types of findings and a patient is still experiencing spine-related pain, there are ways of investigating and diagnosing facetogenic pain.

The Latest Evidence on Diagnosing Facet Syndrome

A diagnosis of facet syndrome is based primarily on both a clinical and diagnostic exam. Diagnostic imaging such as MRI may or may not show correlative findings as mentioned earlier. Clinically, a spine care provider such as a chiropractic physician or orthopedic surgeon will perform a history and physical examination. In my practice, I utilize an evidence-based approach in aspects of patient care. A common orthopedic test to evaluate the facet joint that's been used for decades is called Kemp's test, where the provider extends a patient backwards and adds slight rotation to stress the facet joint and attempt to provoke or reproduce their pain. According to evidence obtained in the past few years, a positive Kemp's test just by itself may not necessarily be the most efficacious way to rule in the probability of facet mediated pain. An extension-rotation test such as Kemp's clustered with other factors such as the patient's age, if they experience reduced pain with walking, alleviation of spine pain with sitting and several other key characteristics can significantly add weight to a post-test probability (the likelihood of ruling in a condition) and solidify a clinical diagnosis of facet syndrome. These combination of factors are what we refer to as a clinical prediction rule in evidence-based practice. It is crucial during the diagnostic process to rule out other possible factors as to why a patient is experiencing spine pain such as disc herniation, sprain/strain, space occupying lesion, etc. before considering facet syndrome as a primary working clinical diagnosis.

Treatment Options for Facet Syndrome

Following a thorough evaluation and clinical diagnosis, a trial of conservative care modalities including spinal manipulation, ultrasound, interferential current, laser therapy and active therapeutic exercises may be deemed a reasonable treatment plan. In the event that conservative care fails after 4-6 weeks as evident by periodic re-evaluations, a script for advanced imaging to assess the region and/or referral to interventional pain management is typically warranted.

Interventional pain management physicians (or physiatrists) at this point in a care plan can do a targeted approach to determining if the facet joint is a pain generator. Under X-ray guided fluoroscopy, the provider may inject a small amount of contrast agent to pin-point the exact anatomical location before administering an anesthetic medication (such as lidocaine) around the facet's medial branch nerve; this is a diagnostic procedure called a medial branch block. If this numbing medication provides significant relief for the patient, then at this point the probability of facetogenic pain is quite high. Therapeutic options from here can include but are not limited to:

• Facet joint injection: Introducing medications such as anti-inflammatories or steroid into the facet joint under X-ray guided fluoroscopy.
• Radiofrequency ablation (RFA): RFA is the removal of nerve tissue (denervation). This procedure is also known as a rhizotomy. The goal of this procedure is to stop the transmission of pain from the facet joint to the brain by burning the nerve.
• Laser facet ablation: Similar to an RFA, this procedure uses a laser instead of radiofrequency to denervate the medial branch. This may be done in an outpatient setting and reports have shown to have longer lasting effects than a standard RFA.

Pending the outcomes of these interventional procedures, if a patient does not find relief with these avenues of care, surgical options can be discussed with a provider. In summary, for patients who have spine pain and a negative MRI study, there should be consideration to evaluate the facet joint as a potential pain generator.

About Dr. Koser

Dr. Robert Koser is chiropractic physician and owner of HealthSpine Chiropractic in Tampa, FL. HealthSpine Chiropractic is a concierge clinic offering non-surgical spine and joint treatments. On-site treatment options include chiropractic manipulation, spinal decompression, cold laser, and acupuncture. Dr. Koser also serves as a clinical consultant to medical providers, legal professionals, and patients alike. For more information, please reach out directly on LinkedIn or contact him at 844-51-SPINE (844-517-7463).