A nerve entrapment or impingement in the back can cause lower limb and foot pain. The most common form of this is sciatica, something most people have heard of or possibly even had over the years.
A possible cause of foot pain at one or both feet can be from a nerve entrapment at the lower part of the spine at the L4-L5 region.
Anatomy
The tibial nerve is the terminal branch of the sciatic nerve which innervates the sole of the foot and back of the leg. It branches arise from the spin at the level of L4-L5 and if there is an impingement here from a bulging disc, protruding disc, disc herniation or similar, it can cause a burning, hot, stabbing, numb pain, either on its own or all together at the heel or across the entire sole of the foot/feet.
Signs and Symptoms Spinal Radiculopathy
Sudden onset pain in the heel is the most common symptom, your back does not need to be sore which is what oftens confuses patients when we tell them its coming from their back and refer them over to physio. The pain is typically worse when lying down at night or sitting in certain positions while being up on your feet and moving around can often actually help reduce the pain. Insoles and strapping will often make things worse as they will irritate the tibial nerve at the inside of the ankle which is often hyper sensitive due to the irritation in your spine.
Diagnosis
X-Ray or MRI can be useful in diagnosis along with clinical suspicion. But there are test that can be done in clinic to stress test the lower back and see if symptoms can be reproduced. The single leg raise and slump test are both specific and sensitive for this condition. Assessing the range of movement in spinal extension can also help indicate the problem and assessing the posterior compartment for a tightness can be an indication but much less so.
Differential diagnosis
Tarsal tunnel syndrome
Baxters nerve entrapment
Inflammatory arthrtitis
Spinal Radiculopathy Treatment
If we suspect this issue, we will refer you to physio for a spinal assessment and they can treat or if required refer you on for further imaging of the spine and possible spinal injections.
Surgery
This can be an option is required if all treatments fail.