Durkan Test

Durkan Test or as it called the carpal compression test is used to test for Carpal Tunnel Syndrome CTS where the median nerve is compressed in the carpal tunnel of the wrist. It was first described by JA Durkan in 1991.

How do you perform the Durkan Test?

With the patient seated with elbow flexed 30 degrees, forearm supinated, and wrist in neutral position, the examiner places both thumbs over transverse carpal ligament and applies 6 pounds of pressure for 30 seconds maximum or with an atomizer bulb attached to a manometer.

What does a positive Durkan Test mean?

• The Durkan Test is positive if the patient have symptoms of numbness, pain, or paresthesia in the median nerve distribution (the three lateral finger with the lateral half of the forth one).
• Note the interval between the application of pressure and the onset of numbness, pain or paraesthesia in the median nerve distribution (The average interval is 16 seconds in carpal tunnel syndrome).

See Also: Carpal Tunnel Syndrome

Sensitivity & Specificity

A study by M Richter found that the Durkan Test or Carpal Compression Test has a high value of clinical diagnosis in carpal tunnel syndrome:

• Sensitivity: 87 %
• Specificity: 96 %

This study also found that the combination of Phalen test with Durkan’s test has a sensitivity of 94% and a specificity of 96%, thus equalling the respective values for electrophysiological testing (nerve conduction velocity, EMG) which so far is regarded as the golden standard diagnostic test for carpal tunnel syndrome.

See Also:  Phalen Test

Diagnostic Utility of the Carpal Compression Test for Carpal Tunnel Syndrome diagnosis:

Population	Reference Standard	Sens	Spec
82 patients presenting to a primary care clinic, orthopaedic department, or electrophysiology laboratory with suspected cervical radiculopathy or carpal tunnel syndrome	Needle electromyography and nerve conduction studies	.64	.30
228 hands referred for electrodiagnostic consultation regarding suspected carpal tunnel syndrome	Nerve conduction studies	.28	.74
232 patients with carpal tunnel syndrome manifestations and 182 controls	Carpal tunnel syndrome diagnosed via clinical examination	.46	.25
132 patients with pain of upper limb	Electrophysiological confirmation	.83	.92

Median Nerve Digit Score

Subjects shaded in hand diagrams based on where they have experienced numbness, tingling, burning, or pain. Diagrams were scored based on the number of digits innervated by the median nerve with distal volar shading.

A score of 2 or more digits was considered positive.

A study on 110 subjects who reported symptoms of burning, pain, tingling, or numbness in the hand, the sensitivity and specificity of Median nerve digit score was 54% and 76%.

Related Anatomy

The median nerve innervates the skin of the palmar (volar) side of the index finger, thumb, middle finger, and half the ring finger, and the nail bed.

The flexor retinaculum (transverse carpal ligament) spans the region between the pisiform, hamate, scaphoid, and trapezium, transforming the carpal arch into a tunnel, through which the median nerve and some of the tendons of the hand pass.

The proximal attachment of the retinaculum is at the tubercle of the scaphoid and the pisiform. The hook of the hamate and the tubercle of the trapezium serve as its distal attachment.

The retinaculum also:

1. serves as an attachment site for the thenar and hypothenar muscles;
2. helps maintain the transverse carpal arch;
3. acts as a restraint against bowstringing of the extrinsic flexor tendons,
4. protects the median nerve.

The structures that pass deep to the flexor retinaculum include:

1. flexor digitorum superficialis (FDS),
2. flexor digitorum profundus (FDP),
3. flexor pollicis longus (FPL),
4. flexor carpi radialis (FCR).
   

The structures that pass superficial to the flexor retinaculum include:

1. the ulnar nerve and artery,
2. the tendon of the palmaris longus.
3. the sensory branch (anterior (palmar) branch) of the median nerve.

The carpal tunnel serves as a channel for the median nerve and nine flexor tendons. The floor of the tunnel is formed by the anterior (palmar) radiocarpal ligament and the anterior(palmar) ligament complex. As mentioned previously, the roof of the tunnel is formed by the flexor retinaculum. The radial and ulnar are formed by carpal bones (hook of hamate and trapezium , respectively). The median nerve divides into a motor branch and distal sensory branches within the tunnel.

Carpal Tunnel Syndrome:

This condition occurs most commonly in women in the 30–60-year age group.

Causes of carpal tunnel syndrome with stenosis from increased pressure within the tunnel include:

1. Local inflammatory processes such as rheumatoid arthritis.
2. Previous fractures of the base of the radius or carpal bones.
3. Tenosynovitis of the long tendons.
4. Mechanical overuse in the workplace or in sports activities.
5. Metabolic disorders such as gout, diabetes mellitus, and amyloidosis.
6. Hormonal changes (such as in pregnancy) can also lead to Carpal Tunnel Syndrome CTS because of swelling within the carpal tunnel.
7. It is sometimes seen in association with myxoedema, acromegaly.

Symptoms and signs of Carpal Tunnel Syndrome include:

1. Night time paresthesia and brachialgia are typical symptoms of nerve compression
2. patients awaken because of pain in the middle of the night a few hours after falling asleep.
3. Other signs include morning stiffness and persistent sensory.
4. At a later stage, motor deficits in the region supplied by the median nerve, with atrophy of the thenar musculature and loss of strength when making a fist.
5. Pinching with thumb and fingers is weak or impossible.

Differential diagnosis should consider the following:

1. Cervical spinal cord and brachial plexus lesions.
2. Pronator teres syndrome.
3. Compression neuropathy in Guyon’s canal.
4. Thoracic outlet syndrome.
5. Osteoarthritis of the first carpometacarpal joint.

Reference

1. M Richter, P Brüser. [Value of clinical diagnosis in carpal tunnel syndrome]. Handchir Mikrochir Plast Chir . 1999 Nov;31(6):373-6; discussion 377. doi: 10.1055/s-1999-13555. PMID: 10637726
2. Durkan, J.A. (1991), “A new diagnostic test for carpal tunnel syndrome”, The Journal of Bone and Joint Surgery, 73 (4): 535–538, archived from the original on 2010-03-05, retrieved 2010-05-04.
3. Calfee RP, Dale AM, Ryan D, Descatha A, Franzblau A, Evanoff B. Performance of simplified scoring systems for hand diagrams in carpal tunnel syndrome screening. J Hand Surg Am. 2012 Jan;37(1):10-7. doi: 10.1016/j.jhsa.2011.08.016. Epub 2011 Oct 5. PMID: 21975100; PMCID: PMC3438892.
4. Wainner RS, Fritz JM, Irrgang JJ, et al. Development of a clinical prediction rule for the diagnosis of carpal tunnel syndrome. Arch Phys Med Rehabil. 2005;86:609-618.
5. Fertl E, Wober C, Zeitlhofer J. The serial use of two provocative tests in the clinical diagnosis of carpal tunnel syndrome. Acta Neurol Scand. 1998;98: 328-332.
6. Kuhlman KA, Hennessey WJ. Sensitivity and specificity of carpal tunnel syndrome signs. Am J Phys Med Rehabil. 1997;76:451-457.
7. El Miedany Y, Ashour S, Youssef S, et al. Clinical diagnosis of carpal tunnel syndrome: old tests—new concepts. Joint Bone Spine. 2008;75:451-457.
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