FOOT PAIN &
FOOT PAIN -
NEUROMA (MORTON'S TYPE)
When foot pain and tenderness occurs under the
ball of the foot, usually the podiatry presentation is either
a metatarsal stress fracture, a nerve is being entrapped or a
painful callus is present. A callous is usually the cause of
the ball of the foot pain if the bone does not hurt with compression
from top and bottom but the skin is tender. A nerve problem is
present if the pain is between the metatarsal bones in the ball
of the foot and the skin and metatarsal heads do not hurt with
squeezing the bones. Review the Corn and Callous Page or the
Metatarsal Stress Fracture Page if you think your problem is
a painful callus or a stress fracture and not a neuroma.
A Morton's Neuroma is
a name given to a scared and enlarged nerve that is between the
two lesser metatarsal heads. The most common place for a neuroma
to occur is between the third and fourth metatarsal heads. The
third and fourth metatarsal heads connect to different bones
in the middle of the foot and with twisting of the forefoot during
gait, these two bones rotate in separate directions causing the
nerve to become pinched. A neuroma is a condition that occurs
from repetitive injury to the nerve that is running under and
between the metatarsal heads in that the nerve enlarges with
scar tissue. The primary cause of the nerve injury is from a
twisting of the forefoot while walking that is associated with
flattening of the foot or pronation. The nerve innervates the
inside bottom area of the two toes that the nerve passes between.
With injury to the nerve, the typical pain that is experienced
is an electrical burning pain that may leave the toes numb intermittently.
Usually the pain is not subtle but very obvious and occurs on
and off during weight bearing. The pain can also continue into
the night even after the foot is rested. The clinical examination
is classic for radiating pain when the nerve is pushed on from
below and between the metatarsal heads. Sometimes there is even
a click that occurs or a marble feeling to the bottom of the
foot with walking as the nerve becomes enlarged with repeated
injury. With each injury to the nerve the nerve enlarges with
scar tissue that is a mixture of scar and nerve tissue. It is
the repeated scarring that is the cause of the pain as the nerve
tissue has no where go when you are standing on your foot and
the metatarsal bones are above and around the nerve.
Treatment with a new
nerve injury is aimed at changing the way in which you stand
by changing shoes to more supportive motion control athletic
shoe or the Podiatrist can fabricate custom molded foot orthotics.
Cortisone injection therapy is the first line of treatment to
try to reduce the amount of inflammation around the nerve and
to relieve pain. Without any other intervention to improve the
alignment of the foot while weight bearing, the cortisone shots
have little long-term affet for curing the neuroma condition.
If treatment is quickly administered upon the onset of the formation
of the neuroma that includes anti-inflammatory medications, the
prognosis is excellent for resolving the nerve injury condition.
If cortisone therapy is partially affective in the pain is improved
but not resolved, alcohol injection therapy is typically the
next tretment. The alcohol therapy uses a diluted alcohol
solution to demyelinate the nerve to stop the nerve from sending
pain messages and then the nerve will regenerate over time and
in doing so a new healthy nerve will reform. In many patients,
up to three ahcohol injections are needed to completely resolve
the patient's neuroma pain. If the nerve injury has progressed
too far with repeated compression injuries, the nerve will increase
in size from a normal diameter of a 1/16th of an inch to over
a half inch from the scar formation. In half the cases, where
a patient has a severe neuroma, half resolve the problem without
surgery and half go on to surgery. Surgery entails either repositioning
the nerve or removing the scarred nerve and placing the cut nerve
end into a small muscle next to the metatarsal. If the nerve
is not implanted into the interosious muscle adjacent to the
shaft of the metatarsal, there is a 60% re-occurrence rate of
having the neuroma return. Extremity nerves that go to the skin
will regenerate unless the nerve end is placed into a tissue
that already has a nerve innervation such as a muscle belly.
For this reason, patients who have had neuroma surgery and not
had the nerve implanted into muscle have a much higher rate of
re-occurrence after surgery. Although rare, if the nerve is implanted
into muscle, the nerve can still develop a painful mushroom at
the end of the nerve where the nerve was cut and implanted into
muscle. The recovery from neuroma surgery is usually minimally
painful if tissues are respected and the podiatric surgeon closes
the tissues in layers and lets down the tourniquet prior to closing
the skin and not after the skin is closed. The patient should
not need to take more that a few pain pills in the first couple
days after neuroma surgery and typically will use anti-inflammatory
medications for the next two weeks to control the amount of swelling
in the area.
Ultimately, early treatment
of a neuroma is important in preventing the progressing of the
scaring of the nerve. Surgery should be reserved for those
patients who have not responded to changing shoe gear, foot orthotics,
cortisone injection therapy, rest and anti-inflammatory medications.
In the hands of a good Podiatric Surgeron, if euroma surgery
is needed, the surgery should go smooth with a rare chance that
the neuroma will return.
© 1999 PLACENTIA-LINDA FOOT AND ANKLE GROUP PODIATRY ASSOCIATES.
All rights reserved.
1275 North Rose Drive Suite 136, Placentia
51280 Yorba Linda Blvd., Yorba Linda
North Orange County Cities of Yorba Linda (92886, 92887), Anaheim Hills (92807, 92808),
Fullerton (92831, 92832,92833, 92834, 92834, 92835, 92836) and
Brea (92821, 92822, 92823).