One of the surprising things about contralateral neurodynamic movements is that they can produce such great pain relief in certain patients that they should not be ignored. In fact I wonder if they should become a routine part of the physical examination for severe radicular pain.
Truthfully, at this stage we're not able to predict who will and who will not respond. Nevertheless, it's worth trying on your patients.
Here's the Rationale
My proposal has always been that, when we perform a neurodynamic test, we apply distal force on the nerve root. This in turn reaches the spinal cord with follows the direction of tension, ipsilateral and caudal. It is this caudal effect that draws the cord downward in the spinal canal and consequently produces a reduction in tension in the nerve root on the other side. This occurs through the vertical component vector in the cord which passes a relaxation effect to the contralateral nerve root.
In diagnosis of nerve root pain, it is often difficult to perform neurodynamic tests without provoking the patient's symptoms. Therefore a contralateral neurodynamic movement can be performed as a means of reducing the patient's symptoms and gaining evidence that the nerve root and/or its associate dura etc. are involved. This can be in preference to using neurodynamic tests on the ipsilateral side to increase or 'reproduce' the patient's symptoms.
In treatment, the contralateral nerve root movement could be used to produce pain relief and therefore form a point from which treatment can be commenced.