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If only I knew…
Who Mister Morton was...

marie catherine bruno owner of the sole mate

A friendly medical chronicle

By Marie-Catherine Bruno, BScPT, Cped(C).

Have you ever felt some tingling or pain between your toes when you were walking? If you have, you probably want to meet Mister Morton!

What is Morton's Syndrome?

Morton’s neuroma (or Morton’s syndrome) is the name of the pathology. A neuroma is an excrescence on a nerve. In the case of a Morton’s neuroma, the excrescence is on one of the Dorsal digital nerves, nerves lying deep in your foot. A neuroma can be benign (like a wart) and grow for no reason, or can also be a form of adaptation for a nerve suffering from too much pressure or friction (basically a callus forming on the nerve).

How Morton's Syndrome Happens

The dorsal digital nerve runs between each of the metatarsal bones (the last bones before the actual toes). There is very limited space for that nerve, so whenever the space is decreased, there is increased pressure on the nerve and one can feel tingling, pins and needles, pain and/or numbness from the pressure on those nerves. In most cases it is felt between the 3rd and 4th toes, but it can actually happen between any toes.

The Cause of Morton's Syndrome

As mentioned earlier, if it is benign, no one really knows why you suddenly grow a neuroma. But if it is from pressure or friction, then we can identify the cause much more easily. If you look at your hand when you make a fist, you will see that at the knuckles where your fingers begin, your hand forms some sort of a dome. This is called the transverse arch. You also have a transverse arch in your foot, situated at the ball of the foot. It is really important that this area is not compressed in any way, because if it is, this is when pressure develops on the nerve. The little nerves running between the bones then get literally squished and send all sorts of messages to your brain (hence the strange sensations like pins and needles). Here are some factors that can put pressure on that arch:

  • Narrow shoes: If your shoes are too narrow for your foot, it squeezes the two sides of the foot and the bones of your transverse arch get pushed against each other, entrapping anything that lies in between them.
  • Bone degeneration: with conditions like osteo-arthritis (OA) and rheumatoid-arthritis (RA), the articular surface of the joint degenerates from wear and tear or chronic inflammation, eating up the cartilage and decreasing the space between the bones. Capsule and ligaments then become too loose and the transverse arch collapses, making your foot slightly wider than it used to be. Your regular shoes then become too narrow…
  • Inflammation: If you suffer from a foot or ankle injury (like a sprain; very popular amongst orienteers), your body will produce some repair material (called lymph) and send it down to the injured area. Unfortunately, your body seems to always produce a little too much of that liquid (hence anti-inflammatory drugs), so the overflow continues down the line. Gravity doing its work, swelling travels downwards. It ends up in the toe area, taking up some of the precious space for nerves and blood vessels.
  • Poor circulation: If you suffer from a systemic disease like diabetes or if you simply have poor venous return, you may have chronic swelling in your feet. Just as above, the extra liquid takes up some space and increases the pressure in this already too narrow space between the metatarsal bones.
  • High heels: Usually not a problem with orienteering (!), they can become a problem at work. High heels move the weight bearing forward, generally on the ball of the foot. Those bones are not designed to support all of the body weight, and the frequent use of those shoes often cause the metatarsal dome (transverse arch) to collapse and further trap the nerves.
  • Rigid shoes: Some cheaper shoes have a sole that is too rigid at the ball of the foot, so in order to bend it when walking, you have to increase the pressure on the ball of the foot, creating the same problem as above with the high heels. If you like wearing clogs, make sure they have a well designed sole, allowing the sole to rock instead of bending.

What to do

Before you think of any invasive treatment, try to take away the cause for the increased pressure on the metatarsal bones. Footwear is fairly easy to modify. If you notice some redness when coming out of your shoes, on either side of your foot (especially at the ball of the foot) your shoes are definitely too narrow. Go shopping! (if you really love these shoes and they do not come in a larger width, then have a shoe maker stretch them with a ball and tongue device). If you think that the sole is too rigid, perform the Egg test (refer to ONA January 2003).

If you suffer from joint degeneration and your transverse arch has collapsed, the only way you can restore it is with a metatarsal pad. It is a domed shaped pad that goes under the foot, just before the ball of the foot. Its function is to support your natural arch, without interfering with the bending of the foot. You can purchase self-adhesive metatarsal pads from the shoemaker, but they might be tricky to position in your shoes. The down side is that you need a pair for all of your shoes. The easiest solution (but not the cheapest) is to have them built in a pair of orthoses (orthotics in Canada) that you can transfer from shoes to shoes. This will support the metatarsal arch, slowing down the wear and tear process and make your foot narrower, decreasing the pressure on the nerves.

For stubborn swelling (either from inflammation or poor circulation), contrast baths work really well (refer to ONA April 2001 for the method). For local inflammation, a topical application (unguent) of a cortisone (or any other anti-inflammatory drug) cream right in the area can also be quite efficient.

In any case, reducing the weight bearing on that foot will also help (use a cane or crutches for a while).
If everything fails, then you move to plan B: injection of xylocaine. Xylocaine is what your dentist uses to freeze your mouth. Injected in the nerve, it keeps it quiet for a while, usually long enough to allow for a pain free healing (as long as the cause has been eliminated).

If you have modified all of the factors that you can possibly modify and you still get pain or other signs from the neuroma, then your last resort is to get it surgically removed.

So next time you feel that tingling between your toes, say Goodbye to Mister Morton!