One of the most common conditions that I see in my clinic is cervical degenerative disc disease (DDD). Patients with cervical DDD will often present with either neck pain, arm pain or some combination of the two. I tell them: “your arm pain is easy to fix with surgery, your neck pain is not.” In this two-part post we’ll examine the causes of neck and arm pain to see why my statement is true. First, neck pain.
Neck pain is quite common and affects 21-67% of adults in the general population. While neck pain is common, its cause can be difficult to elucidate. Neck pain is often caused by trauma. This trauma can be acute (such as whiplash seen after an automobile accident) or chronic (such as poor ergonomics sitting in front of a computer or carrying a purse that is too heavy.) This traumatic neck pain is usually secondary to injury of the muscles that support the cervical spine and if subsequent trauma is avoided, the pain will get better with time.
Neck pain can also be caused by the effects of DDD. When spinal discs degenerate they lose water content and become stiffer which negatively affects their ability to absorb shock and movement. The movement that they used to absorb then gets transferred to the facet joints at the back of the spine (see figure 1). Unfortunately, the facet joints weren’t designed to absorb the extra movement and eventually they too start to degenerate. This causes arthritis of the facet joints, or cervical spondylosis (see figure 2). Now, degenerated, spondylitic facet joints can HURT: the arthritis causes inflammation which in turn causes pain. Also, as a secondary insult, the overlying muscles become spasmodic and painful as they tighten up in an effort to stabilize the degenerated facet joints. The pain associated with this cervical spondylosis is non-specific and is often referred to as “axial neck pain” by spine specialists.
Figure 1: The left image shows a right-sided rear (posterior) view of 2-levels of the cervical spine; the facet joint is indicated by the red arrow. The right image shows a right-sided front (anterior) view in which the spinal cord and nerve roots are included. (source: spineinfo.co.uk)
Figure 2: The left image is a cross-sectional (axial) CAT scan of a cervical vertebral body in a young, healthy patient; note the normal, smooth bony anatomy of the facet joints (red arrows). The right image shows an axial CAT scan of an elderly patient with severe spondylosis; note the irregular, jagged edges of the spondylitic facet joints (blue arrows),
The problem is that patients with non-specific axial neck pain get MRIs (often unnecessarily) and are found to have degenerated discs. Now, if you check an MRI on a group of healthy volunteers you’ll find that more than 80% of them have degenerated discs in their cervical spine yet don’t have pain. (Okada et al, 2011) This suggests that a degenerated disc alone does NOT cause pain. Patients who undergo surgery to fuse a degenerated disc (i.e. in an anterior cervical discectomy and fusion, ACDF, which I’ll discuss in later posts) for axial neck pain only (i.e. without arm pain) will likely NOT see improvement in their axial neck pain. Patients with this condition often do very well with physical therapy to strengthen the muscles of the neck (which naturally stabilize the spine) as well as with targeted steroid injections of the facet joints by a pain management physician.
In the next post we’ll discuss arm pain caused by cervical DDD.
J. Alex Thomas, M.D.
Furman et al: Cervical Disc Disease. Medscape Reference. Updated Dec, 2012. URL: http://emedicine.medscape.com/article/305720-overview
Hoy et al: The epidemiology of neck pain. Best Pract Res Clin Rheumatol. 2010 Dec;24(6):783-92.
Okada et al: Disc degeneration of cervical spine on MRI in patients with lumbar disc herniation: comparison study with asymptomatic volunteers. Eur Spine J. 2011 April; 20(4): 585-591.