Have you ever been grocery shopping and noticed your legs hurt and feel weak but then notice the symptoms go away with leaning over the cart? This is a common symptom patients report, and it’s referred to as the “Shopping Cart Sign.” There are multiple reasons a patient can feel leg pain, numbness and weakness. One of the most common diagnoses that cause these symptoms is lumbar spinal stenosis. Lumbar spinal stenosis is compression of the nerve sac in your lower back related to degenerative changes such as arthritis, disc degeneration and thickened ligaments. When the nerve sac is compressed significantly, patients can develop symptoms we call neurogenic claudication. Claudication can include pain, numbness, tingling, cramping and weakness in the low back, buttocks or hips. When patients stand straight up the nerve canal gets smaller or more compressed but then opens up with leaning forward. This is why you may experience temporary relief of leg pain leaning over the shopping cart.
Claudication can be related to compression of nerves (neurogenic) or related to blockage or reduction of blood flow to the muscles of the leg (vascular). The patient’s risk of having a vascular claudication increases with a history of smoking, diabetes, obesity, high blood pressure and high cholesterol. These two (2) different causes of pain can cause very similar symptoms:
- Lower extremity symptoms that are present with standing, relieved by sitting, located above the knee and have a positive shopping cart sign likely represent more of a nerve source.
- Lower extremity symptoms that are relieved with standing located below the knee can signal more of a vascular cause.
A medical provider can help distinguish between the two sources by a thorough history, exam, and appropriate testing. An MRI of the low back can easily diagnose spinal stenosis, if present. If a vascular source is suspected, blood pressure readings with ultrasounds are more helpful.
Leg symptoms causing limitations of simple day to day activities such as walking need to be evaluated by a medical professional. If a nerve source is suspected, then appropriate testing including x-rays and MRI will likely be ordered. Conservative care including medications, physical therapy and epidural steroid injections can be recommended. If a patient fails conservative options then surgery may be recommended. Lumbar fusions can be very successful for eliminating spinal stenosis and alleviating debilitating leg symptoms. Lumbar fusions allow for a direct decompression of the nerve sac and complete removal of the arthritic bone and thickened ligament. Other alternative surgery options include an indirect decompression of the nerve canal by placing a device between the stenotic levels to flex the spine forward and mimic the “shopping cart sign.”