Differentials
Peripheral vascular disease
SIGNS / SYMPTOMS
An important differential diagnosis is claudication from vascular insufficiency, as both conditions tend to affect older patients. Leg pain of vascular claudication is usually cramping, begins distally, and progresses proximally. Patients with vascular insufficiency will not report improvement of symptoms with lumbar flexion. Patients with vascular claudication will have more difficulty walking uphill due to increased demand for oxygen, while those with spinal stenosis oftentimes find it easier, because they flex forward when walking uphill.
Peripheral circulation should be evaluated in patients with decreased pedal pulses, trophic skin changes, or any other sign of arterial insufficiency.
INVESTIGATIONS
MRI typically does not show radiographic signs of lumbar stenosis.
Lower limb duplex ultrasonography and angiography will confirm vascular insufficiency.
Lumbosacral intervertebral disk herniation
SIGNS / SYMPTOMS
Disk herniations generally cause unilateral radiculopathy (i.e. pain and numbness in a specific dermatome, occasionally weakness in a muscle group) rather than neurogenic claudication. Onset is generally acute. Straight leg raise is often positive. Disk herniation is generally more common in younger patients (30 to 60 years old).
INVESTIGATIONS
MRI shows paracentral, lateral, or foraminal disk herniation with no, or insignificant, narrowing of the spinal canal.
Spinal compression fracture
SIGNS / SYMPTOMS
With thoracolumbar compression fracture, pain usually occurs in the mid or upper back. Patients give a history of trauma, prolonged steroid use, or osteoporosis in the older population (pathologic osteoporotic fracture).
Neurogenic claudication does not occur unless there is retropulsion of fracture fragments at the level of the cauda equina. Rarely do patients develop thoracic radiculopathy or myelopathy from retropulsion of fracture fragments at the level of the spinal cord.
INVESTIGATIONS
Plain x-rays, CT, or MRI demonstrate fracture.
Metastatic disease of the spine
SIGNS / SYMPTOMS
May be a history of prostate, breast, lung, kidney, thyroid, or other malignancy and/or unexplained weight loss. Back pain is often the predominant symptom and is usually worse at night. Patients often are unable to find a position of comfort. Pain from metastatic disease may be out of proportion to the usual back pain associated with degenerative changes.
Back pain and neurologic symptoms are present for a relatively short duration (days to a few months). Neurologic symptoms are more common than in lumbar stenosis and may include significant muscle weakness, paraplegia, and bladder and bowel dysfunction.
INVESTIGATIONS
Plain x-rays, CT, or MRI show vertebral body and/or pedicle disruption at 1 or more spinal levels.
Vertebral osteomyelitis or discitis
SIGNS / SYMPTOMS
High-risk patients include intravenous drug users, patients on hemodialysis, and those with diabetes mellitus. More common in immunosuppressed patients and those with HIV, in whom a skin or urinary tract infection may lead to spinal osteomyelitis. Patients should be asked about history of recent infection and weight loss.
Neurologic deficits can occur if any epidural abscess develops, but neurogenic claudication does not. Back pain is the predominant symptom.
INVESTIGATIONS
Plain x-rays reveal loss of disk space and erosion of cortical end plate margins.
MRI of the involved vertebral body and disk space shows hypointensity in T1 signal and hyperintensity in T2 signal. Affected areas enhance with gadolinium contrast.
WBC count, C-reactive protein levels, and erythrocyte sedimentation rate may be elevated.
Blood cultures may be positive.
CT-guided biopsy is the diagnostic study of choice.
Primary spinal, intradural, or intramedullary tumor
SIGNS / SYMPTOMS
Primary spinal tumors are rare. Pain from intramedullary tumors is worse at night or when the patient is lying down (compression from venous stasis), and conservative treatment fails to relieve the pain.
Neurologic symptoms from cord or cauda equina compression are more common than in patients with spinal stenosis.
INVESTIGATIONS
Plain x-rays, CT, or MRI show evidence of the tumor.
Ankylosing spondylitis
SIGNS / SYMPTOMS
Usually seen in men and in younger patients (onset at age 30 to 40 years). Causes morning back stiffness, hip pain, and swelling (caused by large joint arthritis). It is not relieved with rest and improves with exercise.
INVESTIGATIONS
Plain x-rays, CT, or MRI show the classic picture of a "bamboo spine" (i.e., multilevel spinal fusion). Sacroiliac joints may be obliterated on plain x-rays.
Test for HLA-B27 antigen is positive.
Trochanteric bursitis and degenerative arthritis of the hip
SIGNS / SYMPTOMS
Pain may radiate to the lateral aspect of the thigh (pseudoradiculopathy) but rarely extends to the posterior thigh or below the knee. Numbness and paresthesias are not dermatomal in distribution. Walking may trigger pain but, unlike in neurogenic claudication, pain is also triggered when the patient lies on the affected side. Symptoms are often unilateral. With trochanteric bursitis, there is significant localized tenderness over the greater trochanter, and Patrick's test is positive (external rotation of the hip increases pain). With arthritis of the hip, range of motion (particularly internal rotation) is limited and painful at the extremes.
INVESTIGATIONS
Plain x-rays, CT, or MRI may show signs of hip arthropathy in the absence of evidence of significant lumbar stenosis. MRI may also demonstrate inflammatory changes along the trochanteric region.
Diabetic neuropathy
SIGNS / SYMPTOMS
History of long-standing diabetes mellitus. Pain in the feet is in a nondermatomal, stocking distribution. The pain is described as burning, constant, and not related to activity. The sole of the foot is usually tender to pressure from the examiner's thumb. Bladder dysfunction might be present because of autonomic neuropathy.
INVESTIGATIONS
Electromyogram shows characteristic findings of multiple axonal sensory mononeuropathies.
Epidural abscess
SIGNS / SYMPTOMS
Presentation can be nonspecific. Fever, malaise, and back pain are the most consistent early symptoms. May be local tenderness, with or without neurologic deficit. Abscess can develop from contiguous spread from osteodiskitis, hematogenous spread, or from direct inoculation from injection, surgery, or penetrating trauma.
INVESTIGATIONS
MRI with gadolinium contrast demonstrates epidural abscess.
WBC, erythrocyte sedimentation rate, and C-reactive protein may be elevated.
Blood cultures may be positive.
Degenerative disk/facet joint pain
SIGNS / SYMPTOMS
In the absence of stenosis, degenerative changes affecting the disk and facet joint can cause back pain that radiates to the buttocks and posterior thighs. Flexion exacerbates pain from a degenerative disk, while extension aggravates facet joint symptoms. Pain is mechanical rather than claudicatory or radicular.
INVESTIGATIONS
Plain radiographs show loss of disk height and degenerative changes.
MRI shows loss of disk hydration and height and facet joint degeneration without neural element compression.
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