1. science
2. medicine
3. surgery

Carpal Tunnel Syndrome
Daniel Robbins
What… is it?
Carpal tunnel syndrome is a
nerve compression syndrome
where the median nerve gets
compressed at the wrists
The carpal tunnel is formed
between the carpal bones of the
wrist and the transverse carpal
ligament. The ligament is an
unyielding thick fibrous tissue
which does not allow for
changes in volume within the
carpal tunnel.
What are the symptoms?
The typical primary symptoms are pain and
numbness and tingling the areas innervated
by the median nerve. Symptoms are often
worse at night and can be brought on by
various activities that increase the pressure in
the carpal tunnel (i.e. involving wrist flexion).
Tests for symptoms
A common test for nerve
entrapment is Tinel’s sign. Tapping
or ‘percussing’ is performed on the
surface of the skin along the nerve
pathway over the suspected area of
the lesion. If this produces a tingling
sensation then the test is positive.
Tinel’s sign(8)
Tests for symptoms
•
Durkan’s test or the pressure
provocation test is performed by
applying firm pressure to the
palm over the nerve for up to 30
seconds to elicit symptoms.
•
The pressure is either applied by
hand approximately or with a
pressure gauge held at
150mmHg.
Durkan’s test (9)
Tests for symptoms
•
Phalen’s maneuever is
performed by positioning the
patient with their wrists in flexion
and placed together in front of
them.
•
The position is held for up to 2
minutes, if the position induces
symptoms the test is positive.
Phalen’s maneuver
(8)
Why do we get it?
• Genetic predisposition…?(3)
• You may also get carpal tunnel syndrome if you:
–
–
–
–
–
–
–
–
start doing a something you aren't used to, such as house painting, guitar, knitting etc.
have rheumatoid arthritis in your wrist joint have osteoarthritis in your wrist as a result of an old
fracture
are pregnant
have thyroid problems
have acromegaly, a condition caused by too much growth hormone (a chemical produced
naturally by your body)
have diabetes
have cysts in your carpal tunnel
take certain medicines, such as the oral contraceptive
• For many people, it isn't known why carpal tunnel syndrome
develops. Other nerve and tendon disorders may produce similar
symptoms.
How Does this Affect the nerve?
Nerve’s as a Pressure Vessel (5)
If nerves are considered as a cylinder
they can be modelled as pressure
vessels. Pressure applied at a set point
can therefore be modelled across the
whole nerve.
The pressure at one end
causes increases in
length and both
decreases and increases
in diameter.
These changes can be quantified. Note
that the denominator in each equation is
the radius. The implication of this is that
large nerves are affected before small
nerves by the same amount of pressure.
Implications of pressure
• Large fibres are affected by pressure more than small fibres
– as large fibres carry signals for tactile sensation this could account for the loss of
sensation prior to loss of pain and temperature sensation(5).
• The loss/reduction of tactile sensation signals could limit
presynaptic inhibition at the spine, therefore increasing pain
sensations (following gate theory)(5).
• Observations of longitudinal sliding suggest that shearing
forces deforming the nerve in a proximal direction are more
severe than those deforming it towards the fingers(4).
• Axoplasmic transport effects?? In theory this would suggest
extracellular pathways would be affected before intracellular
pathways (axoplasmic transport). However, there is no
conclusive evidence as of yet…
Vascular effects
Image taken
from Butler,
Mobilisation of
the nervous
system (1991)
• Reduced vascular return – increased pressure restricts flow through oblique
blood vessels (7).
• Currently it is unclear if symptoms are a result of mechanical compression or
relative ischemia (6).
What… can be done?(1,2)
•
Self-help
– If your condition is linked to the way you use your hands, it's important to try to
change how you do things. Changing the way you make repetitive movements,
reducing how often you do them, and increasing the amount of rest between
periods of activity should help.
– Stretching exercises can help to relieve your symptoms and keep the area mobile.
Some studies indicate that special hand exercises - called nerve &/or tendon and
gliding exercises - can help.
– Mild symptoms can be relieved by resting your hands and wrists regularly and by
applying a cold compress, such as ice or a bag of frozen peas, wrapped in a towel.
You shouldn't apply ice directly to your skin as it can damage your skin.
•
Medicines
– Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen don't seem to
have much effect on carpal tunnel syndrome symptoms unless it's caused by an
inflammatory condition. Diuretics (water tablets) have also been prescribed for
carpal tunnel syndrome but recent studies don't show any benefit.
– Corticosteroid tablets (for example prednisolone) for two to four weeks can provide
relief of your symptoms in the short term but they have side-effects if you take them
for a long time.
– Steroid injections (for example hydrocortisone) into the carpal tunnel. Your pain may
get a little worse for a couple of days after the injection, but symptoms should
improve after that.
What happens after the injection? (1,2)
•
I had a steroid injection for my carpal tunnel syndrome. How long will the
effects of the injection last? Can I just have another one if this wears off?
–
•
About three-quarters of people who have a steroid injection find that their symptoms improve.
However, symptoms come back for some people after a few months. You may be able to
have repeat injections.
Explanation
–
It has been shown that about seven out of 10 of people feel their symptoms get better after a
single steroid injection but the effects don't last for everybody. Some studies have suggested
that about nine out of 10 people will feel their symptoms returning within two years whereas
in other studies about half the people treated with steroid injections are still free of symptoms
after seven years.
–
You can only take steroids for a short time because of side-effects. Although this is true for
steroid tablets, it doesn't apply to steroid injections. You may be able to have a second or
third injection if your symptoms return and the first injection worked for you for a while.
–
You should see your GP and ask his or her advice if you feel your symptoms are getting
worse again.
Other options(1,2)
• Complementary therapies
– You may have heard that acupuncture helps to relieve symptoms of
carpal tunnel syndrome, but there is no scientific evidence to back this
up. Also there is no evidence to suggest that vitamin B6 (pyroxidine)
tablets help.
– There is some evidence that performing yoga reduces pain in people
with carpal tunnel syndrome.
• Non-surgical treatments
– Wrist splints are often recommended for you to use either at night, or
both day and night although you may find they get in the way when
you're doing daily activities. These help to keep your wrist straight and
reduce pressure on the compressed nerve.
– Research indicates that ultrasound treatment can help reduce the
symptoms of carpal tunnel syndrome.
Carpal Tunnel Release 1
Open Carpal Tunnel Release
The surgeon makes a 2-5 inch incision in the lower palm and wrist area. The carpal
ligament is opened. This frees the median nerve. The incision is closed with stitches.
A bulky bandage is applied to the wound, with care taken to ensure that digit
movement is NOT restricted.
Effective release of TCL has been
shown to increase carpal tunnel
volume by 24% (6).
Carpal Tunnel Release 2
•
Endoscopic Carpal Tunnel Release
•
A tiny, ½-inch incision is made on the palm side of the wrist. A miniature fiber
optic camera is passed through. This camera allows the surgeon to view the
inside of the carpal tunnel. Another tiny incision is made. Surgical tools are
passed in. While looking at the monitor, these instruments are used to release
the carpal ligament and free the median nerve. After the camera and instruments
are removed, a few stitches are necessary to close the incisions. A bulky
bandage is placed over the wounds.
Outcome
• You may have to wear a brace or splint for
several weeks after surgery.
• Complete recovery may take 4-6 weeks or
longer. The numbness or tingling in your hand
and fingers usually improves rather quickly. Your
grasp strength will very slowly begin to improve.
You may be given special exercises or be
advised to attend physical therapy. This will
further improve the strength and mobility of your
hand and fingers.
Splints
Possible post surgery problems
• General
•
•
•
PO palmer discomfort
Scar tenderness
Weakness
•
(6)
Taken from
Reference 10 details
questionnaires sent to American
surgeon who perform carpal
tunnel releases. The following
table is a summary of surgeons
who encountered complications
at some point (though not
detailing out of how many
releases performed).
Complications
Lacerations
ECTR
OCTR
(708 surgeons)
(616 surgeons)
Median
100
147
Ulnar
88
29
Digital
77
54
Vessel
121
34
Tendon
69
19
Taken from (10)
Ref’s/Further Reading
1.)http://www.aurorahealthcare.org/yourhealth/healthgate/getcontent.asp?URLhealthgate
=%2214786.html%22
2.)http://hcd2.bupa.co.uk/fact_sheets/html/carpal_tunnel.html
3.) Bland,J. (2007) Carpal tunnel syndrome. BMJ August 2007
4.) McLellan, D,L. and Swash, M. (1976) Longitudinal sliding movements of the upper
limb. Journal of Neurology, Neurosurgery and Psychiatry 39, 566-570
5.) Macgregor, R.J. Sharpless, S.K. and Luttges, M,W. (1975) A pressure vessel model
for nerve compression. Journal of the neurological sciences 24: 299-304
6.) Rodner, C,M. and Katarincic, J. (2006) Open carpal tunnel release. Techniques in
orthopaedics 21(1): 3-11
7.) Butler, D. (1991) Mobilisation of the Nervous System, Churchill Livingstone
8.) Urbano, F.L. (2000) Tinel’s sign and Phalen’s maneuver: Physical signs of carpal
tunnel syndrome. Hospital physician July 2000
9.) Durkan, J.A. (1991) A new diagnostic test for carpal tunnel syndrome. Journal of bone
and joint suregry Vol.73-A No:4 April
10.) Palmer, A.K. Toivonen, D.A. (1999) Complications of Endoscopic and Open Carpal
Tunnel Release. The journal of hand surgery Vol. 24A No.3
Any Questions???