For people with ALS anxiety, foot drop is often at the top of their worries. They may imagine foot drop and wonder if it’s ALS or a brain tumor causing it.
• ALS can cause foot drop.
• A brain tumor can cause foot drop. The tumor may be primary (originating in the brain) or a metastasis from a distant site.
Interestingly, for those individuals who – every time they get swept into the foot drop panic vortex – think in a binary way (ALS vs. brain tumor), they need to realize that foot drop actually has many other possible causes including some very harmless ones (e.g., sciatica from nerve root compression, lumbar cysts, excessive leg crossing).
Comparing foot drop from ALS and that from a brain tumor is quite challenging. In both cases, the condition will come on more gradually than suddenly and acutely – as it would from a stroke.
Next, foot drop from ALS is tremendously more common than from a brain tumor.
In addition, “Brain tumor will usually affect an entire arm or leg; sometimes weakness or numbness,” says John M. Abrahams, MD, with Brain and Spine Surgeons of New York, chief of neurosurgery at Northern Westchester Hospital, and founder of the Westchester Neuroscience Research Foundation which is studying the genomic profile of malignant brain tumors.
When a brain tumor affects the foot, “The patient will usually experience a clumsy or ‘dead’ limb that does not do what they expect; they may drag the leg or have a limp arm.”
When people present to a doctor with foot drop, many tests may be given, since this malady can have so many causes from so many different kinds of conditions such as diabetes, a herniated disc, nerve injury from athletics and lymphoma affecting the sciatic nerve.
“ALS is purely motor affecting strength and not sensation, and both are present without pain,” says Dr. Abrahams.
“In the beginning it may be hard to differentiate [between ALS vs. brain tumor], but a physician would perform an MRI of the brain. If there is no findings, the diagnosis of ALS is much greater if there is diffuse weakness with muscle atrophy.”