Carpal Tunnel Syndrome

Definition

• Sign and symptoms secondary to compression of the median nerve in the carpal tunnel

History

• CTS First described bySir James Paget 1854

• First CTR performed Sir James Learmonth 1933

• Popularised by Phalen in the 1950s with a series of articles

• Introduction of endoscopic release 1985-1987– Dr Agee, Dr Chow, Dr Okutsu

Anatomy - median nerve

Attachment of the transverse carpal ligamentContent of the carpal tunnelRelationship with the Guyon’s tunnel

Anatomy - Carpal Tunnel• The bony borders are: radially, the tubercle of the scaphoid and the

tubercle of the trapezium; ulnarly the triquetrum, pisiform and hook of the hamate. The lunate lies in the floor of the tunnel.

• Nine tendons run through the tunnel: the 4 FDS, the 4 FDP, and FPL. FCR runs in a separate fascial compartment on the radial side of the tunnel. The middle and ring FDS tendons are superficial to the index and little finger FDS tendons. The FDS and FDP tendons all share a common sheath; the tendons appear to be invaginated into the sheath from the radial side. The FPL tendon has its own synovial sheath.

• The recurrent motor branch can be extraligamentous; subligamentous; transligamentous. Rarely, it can take origin from the ulnar side of the median nerve, and it can come to lie on top of the transverse carpal ligament.

Anatomy - PCB median nerve

Extra-ligamentousSub-ligamentous

Trans-ligamentous

The recurrent motor branch of the median nerve

Microstructure of the median nerve in the carpal tunnel

• The nerve is composed of 6-40 fascicles with an average of 24. Epineurial tissue makes up around 42% of the nerve.

• Sensory fibres outnumber motor fibres 9:1. The motor nerve fibres are situated anteriorly.

Physiology• Excursion of the nerve

– with flexion/extension is 7-14mm at the wrist– 5-7mm at the elbow.

• Resting pressure in normal patients is 2.5mmHg.– Full flexion or extension increases the pressure to 30mmHg in normal

patients– 90-100mmHg in patients with CTS– Contraction of finger and thumb flexors may increase pressure 3-6

times above resting values.• Reduced epineural blood flow is the earliest manifestation of

nerve compression– and may occur at a pressure of 20-30mmHg.– Reduced axoplasmic transport occurs at pressures of 30mmHg.

Pathophysiology of CTS• Night numbness is caused by a number of factors:• Horizontal position results in a redistribution of fluid

to the upper limbs• Drainage by the action of the muscle pump is

diminished• There is a tendency towards wrist flexion at night• The blood pressure drops during late night and early

morning, resulting in decreased perfusion pressure

Epidemiology• Carpal tunnel syndrome is the most common

compression neuropathy.• Median age is 51. • Women are affected 4:1• More common in industrialized societies.• High rate of bilateral compression. • More common in the dominant arm.• 50% associated with Raynaud’s phenomenon.

Aetiology• Reduction in the size of the carpal tunnel:

– Trauma– Acromegaly– osteoarthritis

• Increase in the volume of the contents of the carpal tunnel:– Inflammation: Nonspecific tenosynovitis of the flexor

tendons; RA; gout; amyloid.– Swellings: ie. Ganglia; lipoma; tumour.– Endocrine abnormalities: ie. Pregnancy; diabetes; thyroid

disease.• Congenital developmental conditions

– Persistent median artery– Abnormal muscle bellies - eg. FDS, palmaris profundus– Proximal or hypertrophied lumbricals

Symptoms• Nocturnal numbness and paraesthesias almost

pathoneumonic– This is because of redistribution of blood from the legs

while the patient is recumbent, with dilation of blood vessels in the carpal tunnel.

– Shaking the hand gets the blood out of the dilated vessels.• The pain should radiate only to the elbow.• The patient may complain of dropping things.

Signs• Numbness doesn’t have to be exactly anatomical but there should be a

big difference between the thumb and little finger. – Numbness often affects the middle finger first then the thumb and

index.– The palmar sensory branch should be spared so there should be

normal sensation over the thenar eminence.• Thenar wasting is a late sign and implies you have missed the boat.• Phalen’s sign may be positive with either volar flexion (Phalen’s volar test)

or dorsiflexion (Phalen’s dorsal test). Overall sensitivity of 75%, specificity of 0.47.

• Tinel’s sign has a sensitivity of 0.60 and a specificity of 0.67. • Durkan’s direct median nerve compression test is the most sensitive

(0.87) and specific (0.90).

Phalen’s Test

Durkan’s Test

Nerve Conduction Studies• The main benefit of NCS is to provide objective evidence for

the diagnosis.• False negative rate of 8%. (These patients have symptoms

and respond to carpal tunnel release but have normal NCS).• EMG evidence of denervation of the thenar muscles provides

evidence of the severity of compression.• Discrepancy between clinical findings and NCS

– Interestingly, no consensus could be reached regarding the patient with classic/probable symptoms without abnormal NCS findings. This is the group where diagnosis is often debated between hand surgeons and neurologists.

DDx

1. Pronator syndrome: – compression by the ligament of Struthers, supracondylar process, bicipital

aponeurosis, within pronator teres and under FDS arch. Hand numbness and nocturnal pain and numbness is rare.

2. Anterior interosseous syndrome3. Brachial neuritis4. Thoracic outlet syndrome5. Cervical radiculopathy6. RSD7. Raynaud’s phenomenon8. TIA

Treatment: Non-surgical

• Only if no sign of motor damage.• Reduce oedema with diuretic or steroid. • Splint to reduce nocturnal flexion – splint in

neutral.

Steroid Injection• Transient relief occurs in 80% of patients after steroid injection• But only 22% of patients with steroid injections are pain free at 12 months

(These patients were also splinted).– It is most useful early in the disease, when there has been less than 1

yr of symptoms– there is no weakness or thenar atrophy – less than 2ms prolongation of distal motor and sensory latencies.

• Technique of injection:– a 22-gauge needle is introduced between FCR and PL– angled dorsally and distally at 45 degrees– It is advanced until it reaches the floor of the tunnel, and then

withdrawn 5mm– A water soluble preparation is used

• e.g. dexamethasone acetate plus lignocaine• if any immediate paraesthesias occur the injection is stopped.

Non-surgical treatment (other than steroid injection) for carpal tunnel syndrome

[Review] Volume (1), 2006, [no page #]The Cochrane Library, Copyright 2006, The Cochrane Collaboration

O'Connor, D; Marshall, S; Massy-Westropp, NDate of Most Recent Update: 15-August-2005

Implications for practice:• Moderate evidence shows significant short-term benefit from

oral steroids.• Limited evidence shows significant short-term benefit from

splinting• yoga and carpal bone mobilization do not produce significant

benefit.

Surgical Treatment

• Open Carpal Tunnel Release– Open technique– Limited incision technique

• Endoscopic Carpal Tunnel Release(1985)– Two incision technique Dr James Chow (Southern Illinois)– Distal single incision technique Dr Michael Murphy (John

Hopkins Univ, Baltimore)– Proximal single incision technique Dr John Agee

(Sacramento, California)

Open Carpal Tunnel Release-Surgical Landmarks

Open carpal tunnel release

-Structures to avoid1. Palmar cutaneous

br of median nerve2. Superficial palmar

arch

Open Carpal Tunnel Release

Postoperative course and results for Open CTR

• Grip strength returns to normal in 3 months.• Surgery is most successful when done early; Patients with

intermittent numbness do better than patients with constant numbness.

• Overall excellent results in 80% (Mayo clinic). 5% have worsened function.

• MRI shows a 20-30% increase in the carpal tunnel volume after surgery. MRI also shows that Guyon’s canal enlarges after carpal tunnel release.

• Measurement of pressures within the carpal tunnel before and after release demonstrate marked decreases in resting pressures after release of the ligament.

Endoscopic Techniques - CTR

• Two incisions• Distal one incisions• Proximal one incisions

Two incisions technique by James ChowSlotted tube techniqueAdv: Visualise the distal and proximal margin of TCLDisadv: Two portals. One portal in the palm

Single distal portal endoscopic techniqueAdvantage: Visualise the superficial arch and the distal margin of TCLDisadvantage: the incision is in the palm

Single distal portal endoscopic technique

single proximal portal technique-John Agee from Sacrimento California-The equipmenmt is manufactured by Microaire Pty Ltd.

Endoscopic carpal tunnel release-single portal technique

Outcome:Endoscopic vs Open

The Cochrane Database of Systematic ReviewsSurgical treatment options for carpal tunnel syndrome [Review] Volume (1), 2006, [no page #]Scholten, R; Bouter, LM; Gerritsen, A; Uitdehaag, BM; de Vet, HCW; van Geldere,DDate of Most Recent Update: 17-August-2005

Cochrane Neuromuscular Disease Group.Dr. Rob Scholten, Director, Dutch Cochrane Centre, Academic Medical Center, RoomJ1B - 108-1, P.O. Box 22700, AMSTERDAM, 1100 DE, NETHERLANDS. Phone: +31 20 5665602, Fax: +31 20 691 2683, E-mail: cochrane@amc.uva.nl, NBackground: Carpal tunnel syndrome is a common disorder, for which severalsurgical treatment options are available.

Objectives: To compare the efficacy of the various surgical techniques inrelieving symptoms and promoting return to work and/or activities of dailyliving and to compare the occurrence of side-effects and complications, inpatients suffering from carpal tunnel syndrome.

Search strategy: We updated the searches in 2003. We conducted computer-aidedsearches of the trials register of the Cochrane Neuromuscular Disease Group(searched in July 2003), the Cochrane Central Register of Controlled Trials (TheCochrane Library, Issue 2, 2003), MEDLINE (January 1966 to August 2003), EMBASE(January 1980 to August 2003) and tracked references in bibliographies.

Selection criteria: Randomised controlled trials comparing various surgicaltechniques for the treatment of carpal tunnel syndrome.

Data collection and analysis: Two reviewers performed study selection,assessment of methodological quality and data abstraction independently of eachother.

Main results:

Twenty-three studies were included in the review. The methodological quality ofthe trials was fair to good. However, the application of allocation concealmentwas mentioned explicitly in only one trial. Many studies failed to present theresults in sufficient detail to enable statistical pooling. Pooling was alsoimpeded by the vast variety of outcome measures that were applied in the variousstudies.

None of the existing alternatives to standard open carpal tunnel release seem tooffer better relief from symptoms in the short- or long-term. There wasconflicting evidence about whether endoscopic carpal tunnel release resulted inearlier return to work and/or activities of daily living than open carpal tunnelrelease.

Conclusions: There is no strong evidence supporting the need for replacement ofstandard open carpal tunnel release by existing alternative surgical proceduresfor the treatment of carpal tunnel syndrome.

-Reviewed 23 studies RCT-Good methodology-Pooling of results was not possible because of differing outcome measures-alternatives to open CTR does not offer better relief of symptoms-Result of early return to work with endoscopic mean is conflictingConclusion: No evidence to support replacement of open CTR

A Systematic Review of Reviews Comparingthe Effectiveness of Endoscopic and Open

Carpal Tunnel DecompressionAchilleas Thoma, M.D., M.Sc., Karen Veltri, M.Sc., Ph.D., Ted Haines, M.D., M.Sc.,

and Eric Duku, M.Sc.Hamilton, Ontario, Canada

(Plast. Reconstr. Surg. 113: 1184, 2004.)

Controversy persists regarding the benefit of endoscopiccarpal tunnel release compared with open carpaltunnel release for pain, numbness, strength, return towork and function, scar tenderness, and complications.For surgeons, a recommended first source of informationon treatment effectiveness is a review of high-methodologic-quality articles. This review of reviews was undertakento answer this clinical question regarding these outcomes.Cochrane, MEDLINE, EMBASE, CINAHL, and Health-STAR databases were searched using the key words “endoscopiccarpal tunnel,” with limits “review or overview”and dates from 1989 to present. Five key journals werehand-searched. Any review with a reference to at least onerandomized controlled trial that compared endoscopiccarpal tunnel release to open carpal tunnel release was tobe included. Two reviewers independently scanned titlesand abstracts for potential relevance. Selection as relevantwas confirmed through a review of full texts. Disagreementswere resolved through discussion and consensus.The selected reviews were assessed for methodologic qualityon the basis of the scale of Hoving et al. Of 48 articlesinitially identified, seven pertinent reviews were selected.Of these seven, three reviews of high methodologic qualityconcurred that there is no difference between the twotechniques in symptom relief and that the evidence isconflicting for return to work and function. The risk ofpermanent median nerve injury does not differ betweenthe techniques. The reviews indicated that the endoscopiccarpal tunnel release technique is worse in terms of reversiblenerve injury but superior in terms of grip strengthand scar tenderness, at least in short-term follow-up. Severaltrials have not been incorporated in these reviews andstatistical pooling has not been conducted. Further systematicreview with meta-analysis may permit more definitiveconclusions about the relative effectiveness of thesetwo techniques, particularly with regard to return to workand function.

Controversy between the two techniquesReviewed articles from 1989-200248 articles on the topic7 articles are pertinent to the question3 of high quality methodology-both techniques relief symptoms-conflicting result regarding return to work and function-no difference in the risk of median n. injury-endoscopic has worse reversible nerve injury-Endoscopic has superior grip strength and and less scar tenderness

Point for discussion

• ECTR & OCTR ONLY relieve the mechanical component of the pathology

• i.e. that they do not address the biochemical, pathophysiology, endocrine or hormonal aspects of the disease

• i.e. we can perform a brilliant CTR but if the nerve has more than a mechanical problem then the pt will not get a full relief.

Point for discussion

• When Durkan’s, Phalen’s & Tinel’s tests are all negative, that the nerve is "no longer able to be irritated"

• ie that it has undergone some pathological change, such as intra-neural fibrosis or other, that prevents a positive response.

Complications• Early

– Transection of the median nerve or the superficial arch– Haematoma– Pain, swelling and stiffness– Recurrent Branch injury– Infection

• Late– RSD– Hypertrophic scar– Median nerve neuritis– Palmar fasciitis– Fibrosis of carpal tunnel– Recurrence

• Revision carpal tunnel release– Only 25% of patients have complete relief of symptoms. 25% have no relief.

The rest have partial relief.