Cyclist’s Palsy
INTRODUCTION
Cyclist’s palsy – It is the compression of the ULNAR NERVE
(C8-T1) at the level of the hand, causes sensory and motor impairments of the
hand in cyclist’s.
Typically the ulnar nerve becomes irritated and compressed
in the wrist within or distal to Guyon's canal, due to the pressure exerted on
the hands on the handlebars.
Both the superficial sensory and deep motor branch of the
ulnar nerve are involved in cyclist’s pal
Compression syndrome of ulnar nerve divided into 3 groups :-
TYPE 1 – Involves both the superficial and deep palmar
branch.
TYPE 2 – Involves only the deep terminal branch resulting
in motor deficits with sensory function intact.
TYPE 3 – Involves only the superficial terminal branch resulting
in no motor deficit.
ANATOMY
Nerve root – C8-T1
The ulnar
nerve is a branch of the medial cord of the brachial plexus.
Travels distally
along the medial side of the arm.
Nerve gives off two
sensory branches which supplies sensation to the dorsomedial hand, the 5th
digit, and half of the 4th digit.
At the wrist, the ulnar nerve
enters the hand by passing through Guyon’s Canal. This tight
tunnel is formed between the hamate,
the pisiform, and the
piso-hamate ligament which helps keep these carpal bones together.
Either within or just
beyond Guyon's Canal, the ulnar nerve divides again in two motor branches. In
the cyclist, it is at or just before Guyon’s Canal where compressive injury to
the ulnar nerve most commonly occur.
MUSCLE SUPPLIED BY ULNAR NERVE
1. FLEXOR CARPI ULNARIS
2. MEDIAL 1/2 OF FLEXOR DIGITORUM PROFUNDUS
3. PALMARIS BREVIS
4. FLEXOR DIGITI MINIMI
5. OPPONENES DIGITI MINIMI
6. 3rd AND 4th lumbricals
7. 4-1 PALMAR AND DORSAL INTEROSSEI
8. ABDUCTOR DIGITI MINIMI
9. ADDUCTOR POLLICIS
10. DEEP HEAD OF FLEXOR POLLICIS BREVIS
GUYON’S CANAL
Guyon’s canal also called ulnar tunnel or ulnar canal, is an
anatomical fibro-osseous canal located on the medial side of the hand. It
extends between the proximal boarder of the pisiform bone and
distally at the hook of the hamate.
The ulnar nerve and
ulnar artery pass through the Guyon canal as they pass from distal forearm to
the hand.
As the ulnar nerve exits the Guyon’s canal it
is divided into deep (motor) branch of the ulnar nerve and superficial
(sensory) branch of the ulnar nerve.
Boarders
Roof: palmar carpal ligament, palmaris brevis and
hypothenar connective tissue.
Floor: transverse
carpal ligament, piso-hamete ligament, pismetacarpal ligament, flexor digitorum
profundus tendons and opponens digiti
minimi.
Medial wall:
pisiform, abductor digiti minimi and flexor carpi ulnaris tendon.
Lateral wall:
hook of hamete, transverse carpal ligament and the flexor tendons.
MECHANISM OF
COMPRESSION
FACTORS such as
-
·Pressure over the hypothenar eminence
·prolonged hyperextension of the wrist,
stretching sensitive structures in the wrist.
·Worn -out gloves and unpadded handle bars
·transmission of vibration in rough roads
can come from overinflated tires
and width of the tire, causing vibration in the hands.
·High saddle or low handlebars causing
excess weight borne by upper limbs
·develops during long-distance or prolonged
cycling and occurs with both mountain bike and road cyclists.
·The position of the hands while holding
the handlebar puts pressure on the nerves in the wrist.
· Especially when cycling downhill, a large
part of the body weight is supported by the hands-on the corner of the
handlebar. This leads to an even higher load on Guyon’s canal in the wrist or
in the carpal tunnel.
·All this can cause neuropraxia, in which
there is a temporary loss of motor and/or sensory function due to blockage of
nerve conduction.
CLINICAL
PRESENTATION
SIGN'S AND
SYMPTOMS
·Numbness
·Tingling
·hand Weakness
·Clumsiness
·Cramping
·Pain
·Possible motor limitation
·Hypo-aesthesia over hypothenar eminence, little finger and medial aspect of
ring finger
·paresis of hand grip, finger abduction and adduction
·difficulty in handling manual breaks
·grip weakness
·ADVANCED CASE DEFOMITY – Partial Claw hand
TINELS SIGN
POSITIVE
FROMET'S SIGN
POSITIVE
WARTENBER'S
SIGN POSITIVE
INVESTIGATION
·Nerve conduction velocity - shows distal latencies in affected muscles (eg.
abductor digiti minimi and first dorsal interosseous)
conduction velocity from above
the elbow to wrist is normal
1. during recovery - Needle examination may show positive waves and polyphasic potentials in affected muscles .
2. After recovery - Needle examination shows no positive waves or fibrilation potential and polyphasic potentials in affected muscles.
polyphasic and biphasic amplitudes present
Thus
electrodiagnostic techniques are useful in the diagnosis and follow up of this
condition
motor
latencies to affected muscles should be measure
sensory distal
delay should also be observed
Needle
examination is useful to determine evidence of reinnervation
electromyographic
evidences shows axonal damage and reinnervation
nerve
conduction studies shows tendency to improve with decreased distal latency
both terminal
branches of ulnar nerve are affected
·Electromyogram may show positive waves in affected muscles ( eg. ADM and
FDI)
interference pattern may be incomplete in affected muscles
no polyphasic potentials
·If there is suspected nerve damage,
imaging through ULTRASOUND and MRI may be needed wil help determine the
location of compression and confirm the diagnosis.
DIFFERENTIAL
DIAGNOSIS
cyclist’s palsy
Fracture of
hamate bone
Hypermobile pisiform
bone
Carpal tunnel
syndrome
Guyon’s canal
syndrome
MANAGEMENT
Depending on the severity of the condition
·
Oral or topical NSAID's medication to treat the
inflammation
·
In severe cases corticosteroid injections may be
required to reduce swelling and ease the pressure on the nerve
·
wrist splinting could help.
·
If other treatments fail, a doctor might try a
corticosteroid injection of the Guyon's Canal or decompression surgery
(i.e. to release the nerve and take away the pressure).
Hand
Strengthening Exercises
1.
Finger bending exercise: start from a stretched hand, bend your fingers of the affected hand in
a right angle and hold for 10 seconds while keeping your fingers straight;
repeat 5 times.
2.
Finger squeeze: place a small object (for example: pen, coin, sheet of paper) between
2 fingers of the affected hand and hold for 10 seconds; repeat 5 times for each
pair of fingers and then move on to the next set of fingers.
3.
Grip strengthening: use a rubber ball and squeeze it with the affected hand; hold for 10
seconds and repeat 10 times. Build up gradually to 3 sets of 10.[13]
Stronger hand muscles will also help to
prevent cyclist's palsy from recurring.
1. Wrist
range of motion: bend the wrist forward and back to neutral position, then
bend the wrist backward and back to neutral position; hold each position for 5 seconds;
repeat 10 times.[13]
If a transient "palsy" has
occurred with temporary motor paralysis with minimal sensory and autonomic
function loss it is a reversible process, if the mechanical compression seizes
the nerve will regenerate on its own and function of the muscles will be
restored.
In
more severe handlebar palsy cases it can take weeks to several months to heal,
depending on the severity of the condition. While the nerve and muscles are
regenerating, the patient needs to interrupt his sport activities for a while.
Modalities include:-
|
ACUTE PHASE |
CHRONIC PHASE |
|
·
Ice(cryotherapy)/heat |
·
Electrical Stimulation |
|
|
·
Low level laser |
|
|
|
|
|
|
RECOVERY
Is spontaneous
Limit cycling to occasional non-competitve
short session
Use of handlebar padding
Corrected inadequate hand position
CYCLIST
PALSY PREVENTION
In order to avoid
cyclist's palsy or to reduce the prevalence of this type of non-traumatic hand and wrist injury
during cycling, it is important to have a look at the prevention
strategies.
Cyclist palsy prevention starts with your bike position.
Make sure your position doesn’t
allow the arms to be fully extended when holding the brake levers.
Aim for around 170 degrees when the
arms are extended .
Your weight must be distributed evenly across your hands on the handlebars
and the arms shouldn’t be carrying more than 20-30% of your weight on a
bicycle.
You can also add bar tape that
includes gel and wearing gel cycling gloves can also help with prevention and
comfort.
Remember it is also important to move your hands around often and try not
to keep them located in a single position for more than 1 hour at a time.
An effective
measure is to cushion the pressure points, by using padded handlebars,
handlebar grips or padded cycling
gloves. This provides an extra layer of fat tissue inside the palm of the hands
so that there is better shock absorption and protection from pressure.
Also, the position of the hands-on the
handlebar is important. The cyclist should try to avoid a hyperextended
position of the wrist. Furthermore, during a long ride, it is advisable to change
hand position regularly.
Individual adaption
of the type of handlebar and the consequential riding position is equally
crucial in the prevention of this ailment. Using an upright horn handlebar
instead of a drop model might be considered for certain individuals. This will
bring the torso position more upright and will diminish the pressure on the
hands.
Another option is
to equip the bike with both a conventional handlebar and an aerobar, which will
allow the cyclist to lean forward and to rest the forearms on pads during
certain parts of the track so that pressure can be taken away from the hands
temporarily during a cycling trip.
Enthusiastic
long-distance cyclists should also adopt a comfortable and resilient riding
posture. If the trunk gets tired or in case of general fatigue, the hands will
invariably bear more weight to stabilize the rider on the bike.
Developing a better posture on the bike
requires strong trunk muscle endurance. Make sure to sit in a comfortable
position on the bike.
The torso should lean forward at about 45° to
50°. The shoulders should be relaxed. The arms should be at 90° to the torso.
The elbows should be slightly bent, not straight or locked. Bent elbows will
act as shock absorbers for any bumps in the road and will alleviate shocks from
the hands. The hands should not be gripping excessively, but resting smoothly
on the handlebar.
Finally, the
cyclist should make sure to ride on the right size of bicycle and to adapt the
position of the saddle and handlebar to make sure that these allow to sit on
the bike in a normal position
