Morton’s neuroma is an enlarged nerve that usually occurs in the third interspace, which is between the third and fourth toes. To understand Morton’s neuroma further, it may be helpful to look at the anatomy of the foot. Problems often develop in the third interspace because part of the lateral plantar nerve combines with part of the medial plantar nerve here. When the two nerves combine, they are typically larger in diameter than those going to the other toes. Also, the nerve lies in subcutaneous tissue, just above the fat pad of the foot, close to an artery and vein. Above the nerve is a structure called the deep transverse metatarsal ligament. This ligament is very strong, holds the metatarsal bones together, and creates the ceiling of the nerve compartment. With each step, the ground pushes up on the enlarged nerve and the deep transverse metatarsal ligament pushes down. This causes compression in a confined space.
When a nerve is pinched between bones, the result is swelling of the nerve. It is this swelling which is referred to as a Neuroma. When the condition occurs in the foot, it is known as a Morton?s Neuroma. Morton?s Neuroma is technically not a tumor. Rather, it is a thickening of the tissue that surrounds the digital nerves leading to the toes. These nerves allow for physical sensation on the skin of the toes. The region of inflammation is found where the digital nerve passes under the ligament connecting the toe bones (metatarsals) in the forefoot. Morton?s Neuroma commonly develops between the third and fourth toes, generally as a result of ongoing irritation, trauma or excessive pressure. In some cases, the second and third toes are involved. Morton?s Neuroma is confined to one foot in most cases, though it can occur in both, particularly in athletes such as runners.
What are the symptoms of Morton?s neuroma? A sharp or stinging pain between the toes when standing or walking. Pain in the forefoot between the toes. Swelling between the toes. Tingling (?pins and needles?) and numbness. Feeling like there is a ?bunched up sock? or a pebble or marble under the ball of the foot.
The exact cause of Mortons neuroma can often vary between patients. An accurate diagnosis must be carefully made by the podiatrist through thorough history taking and direct questioning to ensure all possible causes are addressed. The podiatrist will also gather further information about the cause through a hands on assessment where they will try to reproduce your symptoms. A biomechanical and gait analysis will also be performed to assess whether poor foot alignment and function has contributed to your neuroma.
Non Surgical Treatment
Simple treatments may be all that are needed for some people with a Morton’s neuroma. They include the following. Footwear adjustments including avoidance of high-heeled and narrow shoes and having special orthotic pads and devices fitted into your shoes. Calf-stretching exercises may also be taught to help relieve the pressure on your foot. Steroid or local anaesthetic injections (or a combination of both) into the affected area of the foot may be needed if the simple footwear changes do not fully relieve symptoms. However, the footwear modification measures should still be continued. Sclerosant injections involve the injection of alcohol and local anaesthetic into the affected nerve under the guidance of an ultrasound scan. Some studies have shown this to be as effective as surgery.
Operative treatment of Morton?s neuroma should be entertained only after failure of nonoperative management. Standard operative treatment involves identifying the nerve and cutting (resecting) it proximal to the point where it is irritate/injured. This is usually done through an incision on the top (dorsal) aspect of the foot, although in rare instances, an incision on the sole (plantar) aspect of the foot maybe used. An incision on the sole of the foot works very well, unless an excessive scar forms in which case it can be problematic. Some physicians will attempt to treat Morton?s neuroma by releasing the intermetatarsal ligament and freeing the nerve of local scar tissue. This may also be beneficial.