The spinal cord is surrounded by ligaments and bones that provide support and protection. The central canal containing the cord is constructed from bones of the spine, ligaments, and fat. Depending on the patient's body habi
tus, a central canal anteroposterior (AP) diameter of <14 mm in the cervical region and <15 mm in the lumbar region could be diagnostic (14). Neural compression may be congenital, but may not present clinically until later in life. This process can plague patients with achondroplasia, Down's syndrome, and Morquio's syndrome and those who have a congenitally developed short pedicle.
Trauma is a common cause of spinal stenosis and is not uncommon in athletes. A posttraumatic cord syndrome develops from extreme whiplash and causes edema and swelling of the cord. Whiplash is associated with disc protrusion, herniation, fractures, and subluxation.
Spinal stenosis can also be a slowly progressive process. The central canal and neural foramen are narrowed in degenerative disc disease by endplate osteophytes in the lumbar region and by uncovertebral facet joint in the cervical region. This process is more common in men and generally occurs after the fifth decade. Long-term steroid use or other causes of adipocyte hypertrophy can result in cord or nerve root compromise. Other lesions narrowing the spinal canal may include Paget's disease, osteoarthritis, and epidural hemorrhage.
Facet joint disease of the spine can be age related and is less often found in the young. Age-related degenerative
changes affect the ligamentum flavum. Prior to development of the disease process the ligamentum flavum is tightly stretched. The ligament becomes redundant and hypertrophies as a result of loss of height from disc space narrowing, from thinning of the cartilage that separated the facet joints, as well as from slippage between the facets due to wear. The hypertrophied ligamentum flavum can compress the spinal cord in the narrowed canal; this process can be progressive and lead to spinal stenosis.
History Defining the location and characterizing the pain are important to the diagnosis. The patient's age and mechanical factors, such as conditioning and obesity, may differentiate an acquired from a congenital process. Patients often describe their legs as cramped, tired, or weak. Whereas the discomfort can start when the patient stands, and in some patients standing for prolonged periods worsens the pain, in other patients the pain may start only when they begin to walk. The pain worsens as they continue walking and is often relieved when they stop. Relief of the discomfort has also been reported from crouching down or sitting with a bent posture.
The natural course of this process is a progressive neurological deficit. Therefore, with an acute exacerbation of symptoms, determine if there are signs ofbladder or bowel dysfunction. Spinal stenosis in the lumbar region is often associated with back pain, leg pain, and weakness and numbness in the leg. The leg pain may start in the buttocks and progress to the foot. Patients commonly complain of paresthesias, such as burning or a prickly feeling in the buttocks that may spread to the leg or foot.
Physical Examination The clinical evaluation may not always disclose the level of the lesion. Findings on the examination tend to be vague or inconsistent with a known neuroanatomic pathway. The anxiety and stress of the patient, stiffness, muscle strain, and fatigue associated with the spinal stenosis can masque the true clinical findings. Compression of the peripheral nerve roots from an intervertebral disc, hypertrophied ligament, or tumor can be challenging to locate. Examine the extremities and digits for the presence of focal weakness or muscle atrophy. Although loss of muscle mass may not be readily apparent to patients, the patient may report signs of weakness in the arms or legs, which may be an indication of the nerve level or roots that are affected.
The straight leg raise is often positive in spinal stenosis but may not lateralize. Palpate the paravertebral tissues for point tenderness to differentiate spinal pain from referred pain, such as pyelonephritis or aorta aneurysm. Differentiation of cervical, thoracic, or lumbar lesions can be challenging when back range of motion is limited owing to pain or stiffness.
Evaluate the arms and shoulders for weakness and determine if there is early onset tiredness or claudication in the shoulders with repetitive motion. Evaluate for numbness or tingling in the digits; numbness in the first three fingers has been associated with spinal stenosis near the sixth or seventh nerves. Examine for loss of reflexes and sensory deficit changes. Test the patient for loss of position or vibration sense.
Diagnostic Imaging Plain film imaging of the spine for spinal stenos is often unremarkable, except in congenital causes. In the setting of a congenital spinal stenosis, measurement of the interpediculate distance and an estimation of the level and extent of the spinal stenosis can be performed. Plain film radiographs may reveal spondylitic changes or ossification of the posterior longitudinal ligament. The films assist in excluding other lesions in the adult patient. CT imaging is ideal for diagnosing calcified lesions, such as osteoarthritis in the uncovertebral joints of the cervical spine and the facet joints of the lumbar spine. Short pedicles can be readily identified and measured by CT.
MRI best characterizes compromise of the cord at all levels; anteroposterior compression of the cord; and signal changes associated with edema, hemorrhage, or myel-opathy. In the sagittal projection on MRI the canal may have an hourglass appearance when the perineural fat is obliterated from around the cord and neural foramen. Observe for atrophy of the cord below an area of cord compression and for crowding of the nerve roots in the lumbar region.
Other Tests An EMG may assist in localizing involved nerve and muscle groups and in excluding a myelopathy.
CSF examination may not be as helpful because the fluid protein level may be elevated with a ruptured disc, ligamentous stenosis, and a tumor.
Was this article helpful?