A herniated disc numb foot is a symptom sometimes linked to a lumbar disc issue theorized to be compressing the L4, L5 or S1 nerve roots in the lower spinal region. While it is possible for a herniated disc to enact lateral or foraminal stenosis and compress a nerve in some instances, the symptoms often point out diagnostic errors which explain the typically poor treatment results suffered by the majority of patients with chronic back pain and related neurological expressions.
Numbness in the foot or feet can also occur from herniations which impinge on the actual spinal cord or cauda equina through the process of spinal stenosis. These cases can be difficult to diagnose, since stenosis anywhere in the central canal can affect the feet. Furthermore, since stenotic change is often demonstrated at multiple areas, the symptoms may be linked to the wrong level of compression in many patients.
This article will discuss foot numbness and how it might be related to various disc diagnoses throughout the spinal anatomy.
A numb foot which is blamed on a pinched nerve due to a herniated disc is a very common diagnostic conclusion. This means that a bulging disc has impinged upon a nerve root which eventually serves the neurological needs the part of the foot which is now numb.
If a single nerve root is implicated, the entire foot will never be numb, as this is anatomically impossible. At least 3 different roots would have to be compressed in order for the entire foot to suffer numbness. Additionally, true numbness is a very real symptom of long-term nerve compression. However, objective numbness is not the usual patient complaint. Instead, subjective numbness and weakness, often accompanied by pain and tingling are the norm. This does not represent a logical expression of a pinched nerve, yet these symptoms are still diagnosed as stemming from a foraminal stenosis issue in the vast majority of patients. Misdiagnosis is an epidemic problem when it comes to nerve pain.
When spinal stenosis of the cauda equina occurs, all bets are off, since multiple roots might be affected within the central canal. In these scenarios, detailed and precise nerve conduction testing might be needed in order to verify the disc as the actual source mechanism.
Remember that there are multiple nerve roots which provide sensory signals for the entire foot. Each nerve root deals with a specific area of the foot and symptoms should correlate with the diagnosis. If not, it is wise to consider alternative explanations for the symptoms. Additionally, if the symptoms are more extensive than the diagnosis could possibly entail, it is also advised to consider the alternatives. Finally, if the symptoms are variable and change often in location, severity and expression, it may be best to consider alternative reasons why the foot numbness exists.
I have seen it all in the diagnostic arena. Many patients have clear cut instances of left sided foraminal stenosis, yet have pain in the right foot blamed on the disc issue. Many patients have patent foraminal openings, but are still diagnosed with pinched nerves, despite truly insignificant disc bulging. Many patients have completely innocent herniated discs blamed for enacting sweeping pain conditions throughout the back, both above and below the level of the disc bulge.
All these diagnostic blunders have made me question the integrity of our medical education system. How can we have any hope for things to improve if our doctors can not put together a logical diagnostic conclusion based on the facts, rather than some ridiculous and antiquated medical mythologies and unenlightened guesses?