sep⁄ oct 2010
singapore he alth
21
Spotlight
That tingling feeling
Carpal tunnel syndrome starts with a mild tingling in
the fingers but can point to bigger health issues
The median nerve
supplies sensation
to the thumb, index,
middle and half of
the ring finger
hand may lose its feeling and the muscles
at the base of the thumb become weak.
By Keith G Emuang
Working long hours on the computer takes its toll in many
ways, such as by causing carpal
tunnel
syndrome,
an
uncomfortable condition that affects the hand.
Dr Andrew Chin, Consultant and Head,
Department of Hand Surgery, Singapore General Hospital (SGH), sheds
some light on the condition, its causes
and treatment.
What is carpal tunnel syndrome?
A person with carpal tunnel syndrome
may feel numbness, tingling, pain or
weakness in the hand. Sensation in the
thumb, index and middle fingers and
half of the ring finger is affected when
the main median nerve in the forearm
becomes compressed as it passes through
the carpal tunnel – a passageway of tissues and bones at the wrist and base of the
hand. The symptoms are often felt at night
and after waking up in the morning.
In the early stages, the hand may occasionally feel numb and tingle mildly when
gripping a bus handrail for too long, holding a book, using the telephone or cutlery, typing or doing household chores.
Later, the numbness and tingling become
more persistent, which can keep the
person awake at night. As the condition
worsens, permanent damage to the nerve
may occur. At this stage, much of the
Is there a link between repetitive
motion and carpal tunnel syndrome?
Hand-intensive work, such as prolonged
use of vibrating tools or power tools, has
frequently been associated with carpal
tunnel syndrome, but the debate on the
relationship between repetitive motion
and the condition is still ongoing. Often,
the cause is unknown, although people
who suffer from certain conditions
appear to be more prone due to increased
pressure within the carpal tunnel.
Median nerve
The median nerve
provides motor
control to the
thenar muscles
Thenar muscles
Is carpal tunnel syndrome a sign of
a more serious health condition?
Often, diagnosis of carpal tunnel syndrome reveals a more serious underlying health condition during examination
such as diabetes or rheumatoid arthritis.
Carpal ligament
Flexor tendons
Carpal bones
How is carpal tunnel syndrome
treated?
When the symptoms are still mild, treatment may include minimising wrist
movement, relieving the pain using
splints or braces, and medication, such as
vitamin B6 and anti-inflammatory drugs.
Reducing the swelling of the tissues
within the carpal tunnel through use of
oral diuretics and steroid injections has
been reported. But such treatment only
provides temporary relief and does not
cure the underlying problem.
Surgery to divide the transverse carpal
Adapted from Painful Conditions of the Hand and Wrist
by Department of Hand Surgery, SGH
ligament – the fibres across the palm
below the fingers – that presses down on
the nerve is recommended when the symptoms persist, especially if they are affecting the patient’s quality of life. Minor surgery is often done under local anaesthesia,
with the procedure completed within half
an hour. Keyhole or minimally invasive
surgery, with its advantages of a small
Who is most likely to develop
carpal tunnel syndrome?
Prevent carpal tunnel syndrome with better posture
Sit with your computer
screen at eye level and
your knees slightly lower
than your hip joints.
Let your feet sit
flat on the floor,
not tucked under
your chair.
Keep your
shoulders and
back relaxed.
Do not slouch.
Have your
computer in
front of you
rather than
at the side,
where you
have to crane
your neck.
illustrations: heymans
Take regular
breaks away
from your
computer.
Let your wrists
rest on the desk
in a neutral
position, using a
comfortable pad
to avoid flexing
or extending your
wrist for too long.
incision and shorter recovery, is an alternative to open surgery.
When the nerve has sustained irreversible damage, carpal tunnel release surgery is still recommended. Although the
pre-existing damage will not be reversed,
surgery will help prevent a worsening of
the condition that could lead to complete
paralysis of the thumb muscles.
Women are three times more
likely to develop carpal tunnel syndrome than men. Very fat people whose body
mass index is greater than 29 are 2.5
times more likely to develop carpal
tunnel syndrome than those within
the acceptable range of 18.5 to 24.9.
A narrowing in the carpal tunnel caused by wrist fractures which
have healed abnormally or ageing,
leading to changes in the soft or bony tissue structures, can
increase the risk of developing carpal tunnel syndrome.
People who suffer from hormonal
imbalances – women during pregnancy or nearing menopause – or an
illness such as hypothyroidism will
likely experience fluid retention and
swelling of tissues within the carpal
tunnel, which in turn increase pres-
sure on the median nerve. People suffering from diabetes mellitus and rare
hormonal conditions, such as acromegaly, are also susceptible to carpal
tunnel syndrome. In acromegaly, the
production of growth hormones is
accelerated, leading to an abnormal
growth of bones within the carpal tunnel, narrowing the space that
houses the median nerve and tendons
of the hand.
Carpal tunnel syndrome can be
hereditary, with the risk much higher
if close relatives have the condition.
This is due to inherited physical characteristics, such as the shape of
one’s wrist, which may make a person
more susceptible.
Inflammatory conditions, such as
rheumatoid arthritis, can cause the
lining of the joints and tendons within
the carpal tunnel to swell.