Depending on the location of the compressive forces, the pain goes below the knee to the calf, ankle, and/or foot. The cause of the pressure is usually a protruding disc but it can be a bone spur, tumor, or other space-occupying lesion.
The term pseudo usually means like or mimics the real thing. In the case of pseudoradicular pain, it means the pain goes down the leg but isn't caused by nerve compression or nerve irritation.
How does the doctor know the difference? First, pseudoradicular pain doesn't usually go down past the knee. Second, specific tests for nerve, joint, and muscles can be done to find out where the problem originates (starts).
The results of these tests aren't always clear-cut. So the doctor uses your history, clinical presentation (signs and symptoms), and responses to the tests to make the final diagnosis. For example, Quantitive Sensory Testing (QST) measures pain thresholds for sensory stimuli. Cold, warm, touch, pressure, vibration, and pinprick can be tested to look for nerve impairment.
Most often, true radicular pain will show signs of changes in the threshold for pain sensitivity. The test isn't 100 per cent diagnostic though. About 20 per cent of the time, patients with pseudoradicular pain test positive for sensory loss using this test.
This may mean these two conditions (radicular and pseudoradicular) will be treated (in part) the same way. Usually, the neuropathic pain responds to one form of treatment, while the pseudoneuropathic may improve with a different approach. But if there's overlap, then the patient with pseudoneuropathic pain may require a change in the standard treatment approach.