Have you seen someone tripping over too many carpet edges, or seeming to lift one leg higher when walking, or maybe dragging their toes a bit too much? Some feel as though they’re always walking on their toes, and they’re not just ballet dancers.
How do you walk?
In order to walk, you have to raise your toes and flex your foot back (dorsiflex). This happens so that as you step forward, your heel hits the ground before, or at the same time, as the rest of your foot; it’s something you do instinctively.
That flexing requires the coordination of four muscles in your leg. Their names are long and incomprehensible, but we can call them TA, PT, EHL and EDL. If those four muscles are weak or injured or paralyzed, it’s likely that you can’t do that dorsiflexion, and you may find your toes dragging on the floor and tripping you, or your foot slapping down.
If this happens chronically, it may be that you’re suffering from what we call drop foot. Drop foot is not a disorder in itself, but rather the result of those dorsiflex muscles not getting the innervation they need to do their job. Whether from weakness or paralysis of those muscles, drop foot means that you cannot raise the front part of your foot.
What’s the problem?
The specific nerve that gets in trouble is the peroneal nerve. It’s a branch of the very long sciatic nerve and provides sensation and movement to much of the front and side of your leg, including lifting of your foot. It runs near the surface of your skin on the outside of your knee to your foot.
There is a wide variety of conditions that may lead to drop foot. Multiple sclerosis, Lou Gehrig’s disease, Parkinson’s, cerebral palsy, a stroke, polio or even diabetes can compromise the nerve pathways and cause drop foot.
The peroneal nerve can be injured in an accident or even during knee replacement surgery. It can be affected also by problems toward the bottom of your spine, which is where emerges the nerve root called L5 that branches to the sciatic and then peroneal nerves. There may be disk degeneration or stenosis, narrowing of the passage through which the nerves pass.
In rare cases, there may be lesions or tumors elsewhere in the nervous system that can effect drop foot.
The most common cause, however, is simply compression of the peroneal nerve. This can come from things as simple as habitually crossing your legs, prolonged kneeling or squatting, or wearing a tight leg brace that stabilizes your ankle and ends just below your knee.
Do you have drop foot?
Diagnosing drop foot is, in one sense, very easy. During a physical exam, your doctor can simply observe the strength of those four leg muscles along with how you walk. Checks for numbness or tingling in your shin, as well as the top of your foot and toes, can also indicate drop foot.
And yet, it’s not always quite that simple. As I said, the weakness and numbness can be caused by some more serious conditions. And so, you may also have X-rays, ultrasound, CT scan and MRI, as well as nerve conduction studies.
Whether or not drop foot can be cured depends on what’s causing it. If it results from trauma or nerve damage, then partial or complete remission is possible. If the problem is from more serious conditions with progressive neurological disorders, then drop foot is likely to continue throughout life.
There are two kinds of solution: ones that modulate symptoms and ones that address underlying problems.
Perhaps the simplest, most direct symptomatic relief can be had by fitting you with a brace or splint. With this, the top of the lightweight brace fastens around your calf, and the lower part is an insert that fits in your shoe. The idea is to keep your foot in its normal position so that when you walk, your toes don’t drop down. These braces are called ankle-foot orthotics (AFO).
In cases where there appears to be permanent loss of control, a surgeon may fuse the foot and ankle bones to achieve the same result. Another possible surgery involves transferring the tendon from another muscle that is working.
An alternative to an AFO is the surgical implant of an electrical nerve stimulator. This is a clever idea in which a burst of electrical stimulation is delivered to the peroneal nerve when you lift your foot. The effect is to dorsiflex your foot as you would do normally when walking. It stops stimulating when your heel touches the ground. The timing is controlled by a switch that is implanted in your heel.
Solving the problem
It’s always a good idea to use exercise therapy to strengthen your leg muscles. If the problem results from disuse of those leg muscles, then exercise can be a permanent fix. However, it may have limited effect if the base problem is in your spine, for example. That is, if there are degenerative disks or bone spurs in the spaces around your vertebrae inhibiting signals to those muscles, then the effect of exercising your legs will probably be reduced.
The restriction in the space around the vertebrae in your lower back, compressing the nerves, is called a radiculopathy. This can be from injury or just from aging. With drop foot, the nerve root most likely to be affected by these problems is the one emerging from your spine just below the fifth lumbar vertebra, the L5 nerve root — an L5 radiculopathy.
Surgical treatment of this situation is called an L4-L5 decompression. In this, the surgeon opens up your lower back and physically cuts away whatever is constricting the nerve pathway. The result is generally at least partial recovery of the functions innervated by L5, including, with exercise, use of the four dorsiflex muscles.
Something you may wish to try before and after surgery is myokinesthetic, or MYK, treatment for L5. Using very precise, gentle muscle movements with stimulation, the effect is to have your central nervous system make some changes that will balance and potentially open those spinal spaces a bit. This does not fix degenerative disks nor remove bone spurs. It simply reorganizes your body and nervous system so they work better.
Early is better.
Early detection of problems with your walking can make complete recovery more likely. Tripping more often than usual, tingling on the top of your foot and difficulty dorsiflexing your foot are all symptoms potentially pointing to drop foot.
I advocate paying regular attention to how you feel in all parts of your body. If something changes unexpectedly, let your doctor or other therapist know. The earlier nerve damage or other malfunction is detected, the better will be your chances of avoiding the permanent effects of drop foot.
Bob Keller maintains a holistic pain management practice in Newburyport. His book, “Making Sense of Medicine: Medical Matters Made Simple,” is available locally or online. He can be reached at 978-465-5111 or firstname.lastname@example.org.