FIGURE 3. Sagittal magnetic resonance imaging showing
narrowing of the spinal canal as a result of anterior
herniated discs/osteophytes (left) and posterior
buckling of hypertrophied ligamentum flavum (right).
Imaging and Diagnostic Studies
resonance imaging (MRI) of the cervical spine is the
procedure of choice during the initial screening process of
patients with suspected CSM.15
MRI is noninvasive and provides images of the spine and
spinal cord in several planes (Figure 3). In addition
to giving an assessment of the degree of spinal canal
stenosis, an MRI can identify intrinsic spinal cord lesions
that can also present with myelopathy (e.g., tumors). High
signal changes seen in the spinal cord of patients with CSM
may indicate myelomalacia or permanent spinal cord damage.
Computed tomography (CT) is complementary to MRI (Table 2).
CT may give a more accurate assessment of the amount of
canal compromise because it is superior to MRI in evaluating
Myelography or the intrathecal injection of a contrast agent
is used in conjunction with CT. Since the advent of MRI, the
use of myelography has decreased; however, it still provides
useful information in some instances for surgical planning.
Plain radiographs alone are of little use as an initial
Electromyography is rarely useful in most patients with CSM;
however, it may help in the exclusion of specific syndromes such
as peripheral neuropathy. Somatosensory evoked potentials
(SSEPs) provide a more direct assessment of spinal cord function
(e.g., dorsal column function) than electromyography.
However, SSEPs are nonspecific and therefore their use as a
diagnostic tool is undetermined.
A characteristic physical finding of cervical
spondylotic myelopathy is hyperreflexia.
The presence of
myelopathy on neurologic examination is not unique to CSM.
Therefore, it is important to exclude other diagnoses that
present in a similar fashion. In one study, it was found
that 14.3 percent of patients who underwent surgery for CSM
were later found to have other diagnoses.18
This finding could be an explanation for the lack of
neurologic improvement after surgery in some cases.
Because cervical spondylosis is a universal finding in the
elderly population, it is important to correlate cervical
spondylotic changes with sensorimotor abnormalities
identified on examination.
there is a lack of correlation, there may be a demyelinating
process (e.g., multiple sclerosis). MRI is useful in this
situation for identifying areas of demyelination in the
spinal cord and cerebrum. In addition, a cerebrospinal fluid
examination (e.g., oligoclonal bands) and visual evoked
responses are important diagnostic adjuncts.