Differentiating Cervical Myelopathy From Radiculopathy

cervical myelopathy from radiculopathy.jpg

Differentiating Cervical Myelopathy From Radiculopathy

By: Dr. Gregory Rubin

www.rubinsportsmed.com

Neck pain is a common problem encountered in sports medicine clinics. For the purpose of this review, we will discuss cervical myelopathy and cervical radiculopathy. A more common complaint is axial neck pain, which occurs due to fatigue or injury to the neck musculature and ligaments (Rao, 2002). However, due to the aging population, the incidence of osteoarthritis is increasing. As a result, cervical spondylosis, which is defined as the degenerative osteoarthritis of the spine, can cause a wide variety of pathology (Michael G. Kaiser, 2018). 

Although less common than lumbar radiculopathy, the incidence of cervical radiculopathy is 83 out of 100,000 people (Deanna Lynn Corey, 2014). The incidence of cervical myelopathy decreases to estimates between 4.1 to 60.5 per 100,000 people in North America (Michael G. Kaiser, 2018). The cervical spinal cord is flanked anteriorly by the vertebral body and the posterior longitudinal ligament and then the posterior portion is bordered by the ligamentum flavum (Michael G. Kaiser, 2018). Cervical myelopathy is defined as the loss of fine motor control and coordination with evidence of cord compression based on the clinical practice guidelines published in Global Spine Journal in 2017 (Michael Fehlings, 2017).  The peak age for developing cervical radiculopathy is in a patient’s 50s to 60s (Erik J Thoomes, 2013). With age, the intervertebral disc and uncovertebral joints will degenerate, leading to an alteration of load bearing that can lead to the formation of osteophytes that can cause nerve and spine compression (Michael G. Kaiser, 2018).

Cervical myelopathy

There are multiple etiologies of cervical myelopathy and we will focus on degenerative cervical myelopathy (DCM). This will encompass the nontraumatic compression of the cervical spinal cord from degeneration of the spinal axis (Jetan Badhiwala, 2018; Lindsay Tetreault C. L., 2015 ). The impingement of the spinal cord is typically caused by degeneration of the facet joints, vertebral bodies and disks, and ossification of the posterior longitudinal ligament and ligamentum flavum (Lindsay Tetreault C. L., 2015 ; Michael G. Kaiser, 2018). Ferguson and Caplan divided cervical myelopathy into four separate syndromes (Rao, 2002). These include: medial syndrome, which presents with long tract symptoms, lateral syndrome, which is mostly radicular symptoms, mixed medial and lateral syndrome, and vascular syndrome (Rao, 2002).

The history of cervical myelopathy can be insidious and difficult to identify.  Patients should be asked if they have been dropping any objects or having any difficulty writing, since these symptoms suggest cervical myelopathy (Deanna Lynn Corey, 2014). They may also have difficulty with balance or have hand numbness (Rao, 2002). 

On physical exam, reflexes should be checked and they will typically be brisk if there is cord compression (Rao, 2002).  When evaluating a patient’s neck for a cervical etiology of pain, the patient should be taken through their neck range of motion (Deanna Lynn Corey, 2014). The provider is evaluating for restrictions or pain during any movement. A thorough neurologic exam should also be done, assessing strength and sensation of the bilateral upper extremities (Deanna Lynn Corey, 2014). 

The spurling test can be done to differentiate cervical sprain from cervical radiculopathy. With the patient seated, the provider should place the patient’s neck in extension and then sidebend and rotate toward the side of the pain (KJ Hippensteel, 2019). Then a compressive force is added to the patient’s head and pain that radiates down the arm or behind the scapula is a positive test (KJ Hippensteel, 2019). Shoulder abduction should resolve the pain and if not, the provider should consider shoulder etiologies (Deanna Lynn Corey, 2014). 

Another commonly used physical exam test to assess for upper motor neuron dysfunction is the Hoffman test (Alexandra Fogarty, 2019). The test involves flicking the distal phalanx of the third digit downward and then evaluating for flexion of the thumb or index finger of the same hand (Alexandra Fogarty, 2019). A review published in Spine showed that the test only adds a mild increase in probability for making the diagnosis of cervical myelopathy (Alexandra Fogarty, 2019). 

First line evaluation is plain radiographs assessing for spinal cord narrowing (Lindsay Tetreault C. L., 2015 ).  The diagnosis is typically made with an MRI (Josef Bednarik, 2011). The MRI is assessing for spinal cord signal change and assessing for the amount of canal stenosis (Lindsay Tetreault C. L., 2015 ).

One of the difficulties with cervical myelopathy is that it is seen as a progressive disease. This has led to physicians trying to identify risk factors for which patients with mild myelopathy will progress to severe myelopathy. A systematic review published in Spine in 2013 looked at neurological outcomes in patients with cervical myelopathy (Spyridon Karadimas, 2013).  They were unable to identify age, gender, or radiographic size of involved spinal cord as risk factors for disease progression (Spyridon Karadimas, 2013). 

When discussing treatment of cervical myelopathy, a study was performed by the Japanese Orthopedic Association comparing patients with mild to moderate degenerative cervical myelopathy and randomizing them to conservative or surgical management (Jetan Badhiwala, 2018). They found that at ten years, there was no significant difference in the two groups based on their modified Japanese Orthopedic Association score, which they used to measure neurologic function (Jetan Badhiwala, 2018).

However, some surgeons advocate for surgical decompression at time of diagnosis to prevent any encroachment on the spinal cord with minor trauma (Josef Bednarik, 2011). As a result, a study published in the Journal of Neurology, Neurosurgery, and Psychiatry in 2011 looked retrospectively at a group of patients who experienced cervical spine trauma to see if they could identify any relationship with cord compression and myelopathy symptoms (Josef Bednarik, 2011). They found that there was no statistically significant association between patients who had a traumatic event and the development of discogenic compression (Josef Bednarik, 2011). There have been multiple other trials looking at what the role of surgical decompression in asymptomatic cervical cord encroachment and no clear consensus has been reached (Josef Bednarik, 2011). 

Based on the 2017 clinical practice guidelines in treating degenerative cervical myelopathy, patients with mild degenerative cervical myelopathy should be treated with either surgery or supervised rehab (Michael Fehlings, 2017). Mild DCM is defined as a modified Japanese Orthopedic Association score (Figure 1) of >15, moderate is 12-14, and severe is <11 (Michael Fehlings, 2017).  There is also no role for prophylactic surgery in patients with evidence of cord compression without symptoms (Michael Fehlings, 2017).  

Figure 1  (The modified Japanese Orthopaedic Association Score (Lindsay Tetreault C. L., 2015 )

Figure 1 (The modified Japanese Orthopaedic Association Score (Lindsay Tetreault C. L., 2015 )

Cervical radiculopathy

Cervical radiculopathy is defined as pain that radiates down a patient’s arm due to compression of a nerve as it travels from the spinal cord (Erik J Thoomes, 2013; Michael Fehlings, 2017). Most patients with radiculopathy complain of both neck and arm pain (Jessica Wong, 2014). The nerve roots most commonly pinched are C6 and C7 (Deanna Lynn Corey, 2014). Patients develop pain due to intraneural edema, inflammatory cells, and a change in the vascular response (Deanna Lynn Corey, 2014). In 70% of cervical radiculopathy cases, the location of the impingement is at the foramen (Deanna Lynn Corey, 2014). This is most commonly due to anterior degeneration of the uncovertebral joints and posteriorly of the zygapophyseal joints (Fehlings, 2005). This differs from low back pain, which is typically caused by disk herniation (Fehlings, 2005).

It can be difficult to differentiate cervical radiculopathy from facet arthropathy. Facet joint arthropathy is also implicated in cervical neck pain due to its innervation by the medial branches of the dorsal rami. A study by Bogduk in 1991 published in Spine found that when patients with neck pain received a facet joint injection, 65% experienced pain relief (Charles Aprill, 1991). There have been subsequent studies since then that show that approximately 50% of nonspecific cervical pain was due to the facet joints (John Cavanaugh, 2006).

On average, patients may experience symptoms for 6 months (Erik J Thoomes, 2013). Symptoms can range from sensory or motor symptoms (Rao, 2002). There is no standard diagnostic criteria for cervical radiculopathy (Fehlings, 2005). On physical exam, pain may be worse with neck extension (Rao, 2002). The exam should also include sensory and motor testing of each dermatomal root and reflex testing (Rao, 2002). Radiographs of the cervical spine in a patient with cervical radiculopathy may show osteophyte formation and evidence of neuroforaminal narrowing (Deanna Lynn Corey, 2014). 

In 2013 in the Clinical Journal of Pain, they performed a systematic review looking at the role of conservative treatment in treating cervical radiculopathy (Erik J Thoomes, 2013). What they found was that cervical traction does not lead to any statistically significant pain relief (Erik J Thoomes, 2013). They also failed to find strong evidence for the use of a cervical collar, physical therapy, or manual therapy (Erik J Thoomes, 2013). Pharmacologic first line agents include nonsteroidal anti-inflammatory drugs and the limited use of opioids (Fehlings, 2005). Gaining popularity is an epidural steroid injection done under fluoroscopic guidance. The role of the injection is to decrease inflammation at the level of the affected nerve root. Studies have found that upwards of 60% of patients can have long term relief after these injections (Fehlings, 2005).

However, conservative measures are still considered first line, with surgical interventions being indicated when patients have failed conservative therapy or have progressive or ongoing symptoms (Michael G. Kaiser, 2018). There is no good data showing that patients with cervical radiculopathy are at risk of developing cervical myelopathy (Jessica Wong, 2014). 

Conclusion
The incidence of neck pain will only continue to increase as our population continues to age. In terms of cervical radiculopathy, a majority of patient will improve without any long term neurologic sequelae or chronic pain. However, in patients with cervical myelopathy, our understanding remains limited. It is still difficult to predict which patients will progress to neurologic disability and need emergent surgical evaluation. Overall, neck pain is commonly seen in the population and we need better risk calculators and prognostic aids for patients. 

References

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