Carpal Tunnel Syndrome (OSCE Guide)

1/03/2020

Carpal Tunnel Syndrome (OSCE Guide)

The examination of hand for neuropathies is commonly encountered at OSCE stations. One of the most common scenarios would be carpal tunnel syndrome.

Firstly, introduce yourself and get consent before you proceed to examine the patient.


CARPAL TUNNEL SYNDROME – EXAMINATION

Usually, the command is to examine the hands of the patient, but sometimes you might be given a clue like “This lady presented with tingling sensation in her hands”. The disease is often bilateral.

  1. Ask the patient to spread out the hands for you.
  2. Look for,
    • Wasting of thenar muscles.
    • Scar of a previous carpal tunnel decompression surgery.
  3. Examine the functions of the muscles supplied by the Median nerve.
    • Abductor Pollicis Brevis – Ask the patient to place the dorsum of the hand on a flat surface and lift the thumb towards the ceiling against resistance (Pen touch test).
    • b. Opponens Pollicis – This muscle is usually not tested as it may also be supplied by the ulnar nerve ( an anatomical variation).
  4. Examine the sensory distribution.
    • There is an area of sensory loss over the palmar aspect of the lateral three and a half fingers.
    • However, the sensation over the thenar eminence is preserved.
  5. Special Signs to elicit,
    • Tinel’s Test – Tap over the flexor aspect of the wrist over the midline. If the patient feels a tingling sensation over the distribution of the median nerve, the test is positive.
    • Phalen’s Test – Ask the patient to flex the wrists maximally and keep for one minute. If the patient feels pain in the hands, the test is considered positive.
  6. Try to identify a probable aetiology.
    • Obesity.
    • Hypothyroidism – Goiter? Facial puffiness? Loss of lateral third of eyebrows?
    • Rheumatoid arthritis – Shawn neck deformity? Boutnier’s deformity? Z thumb?
  7. Offer assessment of the patient’s quality of life (QOL).
    • Nocturnal and early morning worsening of symptoms.
    • Effects on occupation or activities of daily living (eg: Washing clothes).

PRESENTATION

This patient who presented with tingling sensation of hands has bilateral thenar muscle wasting but there is no wasting of hypothenar eminence or dorsal guttering. There are no visible surgical scars, suggestive of previous carpal tunnel decompression surgery. Her opposition of the thumbs is weak and the pen touch test is positive, but there is no weakness in finger adduction or extension. There is an area of sensory loss over the palmar aspect of the lateral three and a half fingers and no other areas of sensory loss. Tinel’s test and Phalen’s test are positive. So my tentative diagnosis is bilateral Carpal Tunnel Syndrome (CTS) and I would like to assess her functional disability and probable aetiology.



FREQUENTLY ASKED QUESTIONS

1. What is Carpal Tunnel Syndrome?

It is the symptomatic compression of the median nerve at the carpal tunnel where it runs deep to the flexor retinaculum (Commonest entrapment neuropathy).

2. What are the boundaries of the carpal tunnel?

Roof – Flexor retinaculum. Medial (Ulnar) – Pisiform & Hook of Hamate. Lateral (Radial) – Scaphoid and Trapezius. Palmar aspect – Transverse carpal ligament.

3. What are the structures that pass through the carpal tunnel?

1. Median nerve.
2. Four tendons of Flexor Digitorum Superficialis.
3. Four tendons of Flexor Digitorum Profundus.
4. Tendon of Flexor Pollicis Longus.
5. Tendon of Flexor Carpi Ulnaris (in a separate compartment).

4. What are the structures that pass over the carpal tunnel?

1. Palmar cutaneous branch of the Median nerve.
2. Ulnar nerve.
3. Ulnar artery.
4. Tendon of Palmaris Longus.

5. Why not the sensation over the radial aspect of the palm is affected?

Because the palmar cutaneous branch of the Median nerve is given away proximal to the flexor retinaculum and which passes over it.

6. What are the muscles in hand which are innervated by the Median nerve?

1. All thenar muscles except Adductor Pollicis.
2. Radial two Lumbricals.

7. Name one investigation to confirm your clinical diagnosis?

Nerve conduction studies (NCS).

8. What are the known causes of carpal tunnel syndrome?

1. Obesity.
2. Pregnancy.
3. Hypothyroidism.
4. Diabetes Mellitus.
5. Rheumatoid Arthritis.

9. What are the differential diagnosis?

1. Cervical rib.
2. Cervical spondylosis.
3. Pancoast’s syndrome.

10. What is the surgery?

Carpal tunnel decompression by longitudinally dividing the flexor retinaculum in full length in a bloodless field under local anesthesia.

11. What are other non-surgical treatment options?

1. Local steroid injection.
2. Splinting of the wrist at night.
3. Treating the underlying cause.
Fig

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