Download Video Script Intro Pat M: Carpal Tunnel Syndrome, henceforth

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Video Script
Pat M: Carpal Tunnel Syndrome, henceforth abbreviated as CTS, is a mononeuropathic
entrapment syndrome caused by pressure on the median nerve within the carpal tunnel.
The carpal tunnel is located within the wrist. It is formed by the deep arch of the carpal
bones and the flexor retinaculum, a broad connective tissue sheet that spans the space
between the medial and lateral sides of the arch. The carpal bones that the flexor
retinaculum attaches to are the pisiform and hook of hamate medially, and the tubercles
of scaphoid and trapezium laterally.
The structures that pass through the carpal tunnel include; the four tendons of flexor
digitorum superficialis, the four tendons of flexor digitorum profundus, the tendon of
flexor pollicis longus, and the median nerve. The carpal tunnel functions to keep these
structures in position as they pass into the hand, preventing the tendons from bowing.
Flexor digitorum superficialis originates at the medial epicondyle of the humerus and
bifurcates to attach on either side of the middle phalanx of digits 2-5. Flexor digitorum
profundus lies deep to flexor digitorum superficialis, extending from the ulna to the base
of the distal phalanx of digits 2-5. Together, these muscles act to flex digits 2-5. Flexor
pollicis longus is also a deep muscle, extending from the radius to the base of the distal
phalanx of the thumb. As its name suggests, this muscle functions to flex the thumb.
The tendons of flexors digitorum superficialis and profundus are surrounded by a single
synovial sheath, whilst the tendon of flexor pollicis longus is surrounded by its own
synovial sheath. These tendinous sheaths prevent damage caused to the tendons by
friction and rubbing. This is significant because these tendinous sheaths may become
inflamed and contribute to CTS.
The median nerve lies anteriorly to the aforementioned tendons. It passes through the
carpal tunnel and divides into digital branches in the hand. It supplies the skin over the
lateral 3 ½ fingers, including the nail beds. The median nerve also innervates the first
two lumbricals and the three muscles of the thenar eminence; opponens pollicis,
abductor pollicis brevis and flexor pollicis brevis. The first two lumbricals flex the
metacarpophalangeal joint of digits 2 and 3. Opponens pollicis causes opposition of the
thumb, abductor pollicis brevis abducts the thumb and flexor pollicis brevis flexes the
What structures pass through the carpal tunnel?
Tendons of flexor digitorum profundus
Tendons of flexor digitorum superficialis
Tendon of flexor pollicis longus
Median nerve
All of the above
Answer: E
Jamie: Carpal Tunnel Syndrome occurs as the result of a combination of repetitive
activities and predisposing health conditions. Often it is difficult to isolate a single cause,
hence the condition can be termed idiopathic.
Ultimately however, the causes of CTS result in an increase in pressure on the median
nerve as it travels through the carpal tunnel. Most commonly, this increase in pressure is
due to inflammation of the ligaments and tendon sheaths that pass through the carpal
Some of the main causes are: repetitive wrist actions, bone fracture and regrowth,
underlying illnesses and predisposing conditions.
Repetitive or extreme wrist motions, vibrations, and using fingers with high force all
increase the likelihood of developing CTS. Situations where this would occur include:
Forceful hand movements involved in hammering all day
Repetitive finger movements like those used in typing
Hand to arm vibration when using a power tool
Long periods of work while remaining stationary or in awkward positions
Bone breakage and regrowth can also cause CTS. If someone breaks their wrist or
dislocates the carpal bones, the carpal tunnel space may decrease as new bone growth,
healing bones and bone spurs will begin to reform over the fracture. This leads to
compression of the median nerve and tendons which can lead to tenosynovitis.
Underlying illnesses that contribute to swelling in soft tissues and joints in the upper limb
or reduce blood flow to the hands can also cause CTS. These include: rheumatoid
arthritis, gout, diabetes, lupus, hypothyroidism, all of which increases pressure by
reducing the available area in the carpal tunnel itself.
Other condtions that may cause CTS are: congenital predisposition, over activity of the
pituarity gland, fluid retention, known as edema, during pregnancy or menopause, a cyst
or tumor in the carpal tunnel, and obesity.
What causes carpal tunnel syndrome?
Rheumatoid arthritis, edema, fracture of the fingers and narcolepsy
A lesion in the wrist, obesity, laceration of the wrist and congenital predisposition
Hypothyroidism, rheumatoid arthritis, broken wrist and pectoral tear
A tumor in the carpal tunnel, edema, over-activity of the pituitary gland and
Lupus, power tool usage, throwing a ball and cyst in the lower back
Answer: D
Andrew: The median nerve supplies all the flexors of the forearm except flexor carpi
ulnaris and the medial half of flexor digitorum profundus. It also supplies the palmar
surface of the lateral 3.5 digits including the nail beds and finger tips. Damage that
occurs to the median nerve in the carpal tunnel does not affect the flexor muscles, so
they will still function as normal. However, it will lead to a loss of function of all the thenar
muscles in the hand resulting in a condition known as “ape hand”. The sufferer of ape
hand is unable to abduct their thumb away from the rest of their hand. This inability to
abduct the thumb results in a loss of precision grip.
Similarly, a patient with CTS will feel paraesthesia, commonly known as “pins and
needles” along the lateral 3.5 fingers. The more the nerve is irritated the stronger the
tingling sensation along these fingers will be. Although the median nerve impingement is
localised to the carpal tunnel, the patient may feel pain anywhere along the entire upper
limb. This pain can disrupt daily life and sleep, affecting their quality of life. In severe
cases individuals will be unable to perform basic tasks such as brushing their hair
without pain.
Because the patient cannot abduct their thumb due to impaired nerve supply, atrophy of
the thenar muscles occurs. This can be observed by a decrease in the thenar eminence
over time.
What is not an effect of median nerve damage in the carpel tunnel:
Ape hand
Numbness of the lateral 3.5 digits
Thenar eminence atrophy
Hand of Benediction
Waking during the night from pain
Answer: D
Diagnosis + Treatment
Pat C: Diagnosis of CTS is based on a series of clinical tests and is ultimately
confirmed by electrodiagnostics. Initial tests (such as X-rays, laboratory tests) and
consulting the patient’s medical history are used to assess any possible underlying
medical disorders that may be contributing to or mimicking the condition.
Physical examinations may include asking the patient to:
Produce certain movements: flexion, abduction and opposition of the
Make a grip and testing the strength of the grip
React to sensory stimulation of the skin and two-point discrimination test
on the fingertips
Specific diagnostic tests such as Tinel’s test and Phalen’s manoeuvre work to induce
CTS symptoms, which are indicators of CTS:
- Tinel’s sign test: The Tinel’s sign test involves tapping or pressing on the
median nerve at the wrist. The test is positive if it elicits a tingling or
shock-like sensation.
Phalen’s manoeuvre: For the Phalen’s manoeuvre, the patient is asked
to flex both wrists and orient their hands so that the dorsal surfaces are
pressed against each other. They are then asked to maintain this position
for 60 seconds. If within the timeframe, the patient experiences discomfort
identical to that of carpal tunnel syndrome (increasing tingling,
numbness), the test result is positive. This test measures the severity of
carpal tunnel syndrome: the quicker the onset of symptoms, the severe
the case.
Electrodiagnostic tests are performed to confirm carpal tunnel syndrome provided
the provocative tests are positive. Nerve conduction studies measure the speed at
which an impulse is transmitted from one nerve to the next. The presence of a time
delay or changes in intensity is an indicator of CTS. Electromyography measures
electrical activity and can determine the extent of damage to the median nerve.
Early detection and treatment of CTS is crucial to avoid further damage to the
median nerve.
Resting – patients should avoid activities at home or work that may trigger the
Night splints are custom-made device that immobilises the wrist in a neutral
corticosteroid injections relieve pain symptoms, but may not be effective for longterm resolution.
Surgery is usually considered as a last resort, except for patients with severe CTS. The
procedure involves making an incision through the skin at the base of the palm. A
smaller incision is made in the flexor retinaculum to release the pressure from the
tunnel. The cut is left unclosed, so that through healing, the formation of scar tissue
across the flexor retinaculum expands the volume of the carpal tunnel, allowing it to
accommodate the inflamed tendons and reduce nerve compression. Although the
symptoms are relieved after surgery, a full recovery of the wrist may take several
months during which patients may experience loss of strength at the wrist.
Which ONE of the following clinical examinations involves tapping the median
nerve to elicit paraesthesia at the fingers?
Phalen’s manaoeuvre
Nerve conduction study
Tinel’s test
Westphal’s sign
Answer: D