CARPAL TUNNEL SYNDROME
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clinical syndrome manifested by characteristic signs and symptoms resulting from
an entrapment neuropathy of the median nerve at the wrist
most common compression neuropathy in the upper extremity.
Anatomy
 Space enclosed by the concavity of the carpus and the overlying flexor
retinaculum
 Flexor retinaculum has 3 components
 deep forearm fascia (deep to FCR and FCU)
 transverse carpal ligament
 distal aponeurosis between thenar and hypothenar muscles
 Mean width
 25mm at proximal end
 20mm at the narrowest region at the level of the hook of hamate
 26mm at the distal end
 Mean widening of the transverse carpal arch after carpal tunnel release is
10.4% or 2.7 mm
 Volume measure 5ml. Generally smaller in females
 Contents
 4 tendons of flexor digitorum superficialis (FDS)
 4 tendons of flexor digitorum profundus (FDP)
 All 8 share a common synovial sheath – Ulnar bursa. The sheath does not
invest them completely but is reflected/open from the radial side. Arteries
gain access to the tendons at these points
 1 tendon of flexor pollicis longus, median nerve
 Other structures
 Palmaris profundus arises from the interosseus membrane in
the forearm and passes through the carpal tunnel to insert onto
the dorsal surface of the palmar aponeurosis. Rare finding.
Reported in 1:1600 dissections
 Lumbricals usually originate form FDP tendons distal to the
tunnel, but when fingers are flexed they may be pulled back
into the tunnel
 Small persistent median artery – dominant blood supply to
median nerve in 30% and may significantly contribute to blood
supply of index and middle fingers
 Anomalous palmar cutaneous branch
MRI distal cross section
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Transverse Carpal ligament
 Medial – pisiform and hamate ( hook and radial surface)
 Lateral – scaphoid tuberosity and medial surface/ridge of trapezium.
 Integrity of the TCL is not a major factor in the maintenance of the carpal
arch.
Palmar cutaneous nerve
 From radiopalmar aspect of nerve, 5cm proximal to wrist crease
 Separates from main nerve after 2cm and travels underneath antebrachial
fascia between PL and FCR
 Emerges through fascia 0.8cm proximal to wrist crease and divides into
radial and ulnar branches
Median Nerve
 Enters the canal in the middle or slightly to the radial side of midline, directly
under or dorso-radial to the palmaris longus tendon
 Enclosed by a parietal and visceral layers of loose connective tissue. This
allows it to shift as the hand changes position.
 Shape of the nerve varies as is passes through the tunnel. It starts out oval
and then flattens out.
 With the wrist in a neutral position, the median nerve is seen anterior to the
flexor digitorum superficialis tendon of the index finger or posterolaterally
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between the flexor digitorum tendon of the index finger and flexor pollicis
longus tendon.
May move as much as 20mm in flexion-extension
The nerve can sometimes be split by an accessory lumbrical or the median
artery. The division may be equal or unequal. Sometimes they rejoin distally.
Motor fascicles are generally on the radial side. 78% of cases motor fascicles
occupy radiopalmar position in the nerve, 22% in central palmar portion
Divides into 6 branches distally – recurrent, 2 common and 3 proper
1st lumbrical supplied by radial side proper digital nerve to IF, 2nd lumbrical
supplied by common digital nerve to 2nd cleft
In 56%, the thenar branch travels in a separate fascial tunnel. The thenar
branch commonly comes off distal to the TCL(extraligamentous). Sometimes
it branches off within the tunnel (subligamentous) and sometimes it
perforates the TCL in its own tunnel (transligamentous).
A – Extraligamentous and recurrent (most common 45-90%)
B – Subligamentous (31%)
C – Transligamentous (23%)
D – Originate from ulnar border of median nerve
E – Lie on top of TCL
Topographical landmarks
1. Distal wrist crease is the proximal origin of the transverse carpal ligament (TCL).
The proximal wrist crease corresponds to the radiocarpal joint.
2. Kaplan’s cardinal line – line drawn parallel to the ulnar side of the abducted
thumb and the hypothenar space.
3. The distal end of TCL is at the intersection of the cardinal line and the line of the
ring finger axis.
4. Superficial palmar arch lies 5mm distal to the above point.
5. Hook of hamate is 1cm distal and radial to the pisiform.
6. Kaplan’s landmark is the intersection of the cardinal line and a line drawn from
index/middle finger interspace. This point identifies the motor branch of the
median nerve.
History
 1854 - Sir James Paget first reported median nerve compression at the wrist
following a distal radius fracture
 1913 - Pierre Marie and Charles Foix described the pathology of median nerve
compression underneath the transverse carpal ligament
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1924- Galloway and Mackinnon in Winnipeg, Canada, did the first TCL release in
a patient with a posttraumatic neuropathy. Complicated by neuroma of PCN
1933 - Sir James Learmonth reported TCL release to treat median nerve
compression at the wrist.
1951 – Phalen advocated transverse incision at the distal wrist crease, with
proximal and distal extension as needed
1970 – Taleisnik popularised vertical incision in line with 4th ray
Epidemiology
 Prevalence 1-5% of general population
 prevalence among working individuals is somewhat lower, about 0.5% - suggests
that the majority of cases occur in the non-working population
 50% bilateral
 F>M 3-5:1
o relationships between CTS and women (OC use, menstrual disorders, and
obesity) may be related to pressure on the median nerve due to fat or
edema near the carpal tunnel.
 Most common 4th to 6th decades of life
 Risk factors
1. female sex
2. obesity (BMI>30)
3. age 41-60
4. diabetus mellitus
5. square (width=height) wrists (as opposed to rectangular)
 Smoking is not strongly associated
 Males tend to have worse disease
 Diabetus mellitus is a significant risk factor for bilateral lesions.
 American Society for Surgery of the Hand has issued a statement that the current
literature does not support a causal relationship between specific work activities
and the development of diseases such as CTS.
Aetiology
 Approximately one-third of patients with carpal tunnel symptoms have associated
medical conditions such as inflammatory arthritis, diabetes, pregnancy,
amyloidosis, hypothyroidism and acromegaly (NEJM 1993)
 Local and Systemic factors
o Systemic factors act to directly or indirectly affect microcirculation,
pressure thresholds for nerve conduction, nerve cell body synthesis, and
axon transport or interstitial fluid pressures.
 Acute vs Chronic
Trauma-related structural changes
1. Distal radius fracture
2. Lunate dislocation
3. Posttraumatic arthritis/osteophytes
4. Edema
5. Hemorrhage
6. Burns
Systemic diseases
1. Rheumatoid arthritis
2. Diabetes mellitus
a. Reduces threshold for developing symptoms
3. Thyroid imbalance (especially hypothyroidism)
a. Consider this if recurrent presentation after surgery
b. Causal relationship not clear
4. Amyloidosis
5. scleroderma
6. Hemophilia
7. Alcoholism
8. Raynaud's phenomenon
9. Paget's disease
10. Gout
11. Chronic renal failure/hemodialysis
12. Glycogen storage diseases in children
Anomalous anatomic structures
1. Aberrant muscles (eg, reversed palmaris, palmaris profundus)
2. Unusually extensive lumbricals or FDS/FDP bellies
3. Median artery thrombosis
4. Enlarged persistent median artery
Hormonal changes
1. Pregnancy
a. up to 17% of pregnant women, mostly in third trimester
b. weight gain increases risk
c. most resolve spontaneously after delivery
d. 11% of women reported CTS six months after delivery and 4.3% still
had the condition a year afterward
2. Menstrual disorders
3. Menopause
4. Oral contraceptive pill
5. Acromegaly
Infections
1. TB
Tumors/neoplasms
1. Lipoma
2. Ganglion
3. Fibroma
4. Aneurysm of median artery
Mechanical overuse
1. Vibrating machinery
Differential Diagnosis
1.
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6.
Cervical radiculopathy (double crush syndrome)
Thoracic outlet syndrome
Pronator teres syndrome
De Quervain’s syndrome
RSD
Tenosynovitis
Pathophysiology
 Compression leads to
1. swelling of tenosynovium
2. thickening of transverse carpal ligament
3. focal demyelination of median nerve.
4. Axonal loss in more severe cases
 initial insult is a reduction in epineural blood flow and venous congestion, which
occurs with 20 to 30 mm Hg compression.
 Intracarpal canal pressures in patients with CTS routinely measure at least 33 mm
Hg and often up to 110 mm Hg with wrist extension.
 Continued or increased pressure eventually causes edema in the epineurium and
endoneurium.
 If applied for 2 hours, pressure of 50 mm Hg will cause epineural edema, and if
applied for 8 hours, it will increase endoneural fluid pressure fourfold and block
axonal transport.
 As further injury occurs to the capillary endothelium, more protein leaks out into
the tissues, which become more edematous, and a vicious cycle ensues. The
effects are most pronounced within the endoneurium, since more exudate and
edema accumulate there, unable to diffuse across the perineurium.
 The perineurium resists pressure changes because of its higher tensile strength
and acts as a diffusion barrier creating in effect a "compartment syndrome" within
the nerve.
Histopathology
 Path of flexor tenosynovium shows inflammation in only 10%, but oedema and
vascular sclerosis in 98%
Diagnosis
History
 most common symptom is paresthesias in the distribution of the median nerve –
middle and index most common
 Other symptoms include feelings of clumsiness and weakness in the affected
hand, often made worse with activity.
 Proximal radiation of pain or paresthesias to the elbow or even the shoulder is not
uncommon
 Night pain is a consistent symptom. Theories:
o Phalen postulated that when the hand and wrist are at rest during sleep,
engorgement and relative venostasis occur in the small vessels within the
flexor synovialis, producing swelling, more nerve compression within the
tunnel, and worse pain. Active motion of the fingers and wrist decreases
venous engorgement and relieves pain, a phenomenon consistent with
many patients' histories and their need to shake or exercise their hands to
relieve night pain. It is an interesting theory that emphasizes the vascular
etiology of the disorder, but there is no published evidence to prove the
hypothesis.
o Patients hold their wrists flexed while sleeping, thus increasing the
pressure on the median nerve and causing pain. Therefore, preventing
wrist flexion would be expected to decrease symptoms, and may be why
many patients find it beneficial to wear neutral-position wrist splints at
night.
Examination
 thorough physical examination of the neck and upper extremity should be
performed
 Sensory findings (threshold tests best):
1. Semmes-Weinstein pressure monofilaments: Values greater than 2.83 may
be indicative of CTS.
2. Vibratory sensibility: A vibrating 256-cycle per second tuning fork is
placed against the patient's fingertips. The median and ulnar fingers of
both hands are tested. The test is considered positive if decreased sensation
is perceived.
3. Static and moving 2-point discrimination: Failure to discriminate more
than 6 mm (static) or 5 mm (moving) is a positive finding – this is a late
finding as can remain normal until nearly all sensory conduction has
ceased.
 Thenar atrophy is a sign of advanced CTS of long-standing duration.
 Provocation tests
1. Tinel’s
a. Sensitivity - 25 to 79%
b. Specificity – 60-95%
c. One study showed Tinels to be the most specific (84 percent), but
the least sensitive (32 percent) of all the provocation tests
2. Phalens (wrist flexion)
a. patient's elbows are placed on a table, the forearms are
perpendicular to the table, and the wrists are flexed for 60 seconds.
The test is positive if numbness or paresthesias develop in radialsided digits
b. Sensitivity - 42 to 85%
c. Specificity – 54-98%
3. reverse Phalen's (wrist extension)
4. carpal compression
5. vibration testing
6. Durkan’s pressure test
a. Applies a known standard pressure (150mmHg) over the TCL
b. 10% false positive rate
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No one test is diagnostic
Investigations
Investigations for systemic diseases – hypothyroidism, diabetes
Nerve conduction studies
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most appropriate role for electrodiagnostic testing is as an adjunct to the clinical
assessment in instances where the diagnosis is not clear
Distal motor latencies of 4.5 millisecs and sensory latencies of 3.5millisecs
abnormal
Difference between hands of 1 ms (motor) or 0.5 ms (sensory) abnormal
Electromyography of thenar helpful for signs of denervation
There is no relationship between the nature or duration of pre-operative
symptoms and the severity of the electrophysiological impairment.
There is no relationship between pre-operative nerve conduction impairment and
either successful outcome of surgery (defined as complete symptom relief) or time
to resolution of symptoms after surgery
Imaging studies
 Xray wrist – arthropathy, post trauma deformities
 US and MRI not routinely performed unless masses suspected
 MRI may be useful to assess recurrent symptoms post repair
o following adequate carpal tunnel release, MRI may demonstrate an
increase in carpal tunnel volume of up to 24%, often accompanied by a
change in shape from oval to circular, resulting in increased
anteroposterior and mediolateral diameters.
o incomplete surgical release of the flexor retinaculum can occur and be
detected by a residual increase in T2 signal of the median nerve within the
carpal tunnel and by direct visualization of the still-connected fibers of the
retinaculum.
o Other changes include excessive fat within the carpal tunnel, neuromas,
scarring, and persistent neuritis.
Management
Nonoperative
1. splinting in neutral
o initial trial of full-time splinting for 3 to 4 weeks followed by part-time
night splinting is recommended.
2. NSAIDs
3. diuretics to reduce oedema
o little evidence to support effectiveness
4. treat underlying disease
o often resolves symptoms in hypothyroidism
5. Vit B6 was thought to be good but doesn’t modify disease
6. Steroids – 80% relief (transient), 22% symptom free at 1 year
o Most likely to benefit are those with symptoms <1yr; diffuse and
intermittent numbness; normal 2 point discrimination; no weakness or
atrophy; <1-2ms prolongation in latency for M and S
o 40% of this group symptom free for >12 months
o Injection method
 22 or 25g needle 1cm prox to distal wrist crease ulnar to PL at
angle of 45 degrees (distal and dorsal)
 Recent BJPS article suggest safer to go radial to FCR
 advance until hit floor then withdraw 0.5cm
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1ml of betamethasone (Celestone 5.7mg/ml water soluble) or
triamcinolone (Kenacort A10 10mg/ml) + 2ml of Xylocaine
1%
 withdraw if median n paraesthesias
 splint wrist continuously for 3 weeks
o good response to injection is correlated with an excellent response to
subsequent surgery.
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Conservative management unlikely to work if
1. Older than 50 years.
2. Symptoms lasting 10 months or longer.
3. Continual numbness.
4. The thenar muscles have begun to atrophy
5. Symptoms occur within 30 seconds during a Phalen's test.
If none of above present, conservative management will work in 2/3rd of cases
40% if one present and 20% if 2 present and nearly none if >2 present
Operative
 Indications
1. Failure of conservative management
2. acute CTS
3. severe chronic CTS – thenar atrophy, reduced 2 point discrimination
4. secondary to mass compression
Open technique
 tournique, local or regional block
 Taleisnik advocates incision placement ulnar to axis of flexed ring finger at level
of wrist crease (avoids PCN)
1. Or stay ulnar to PL at distal wrist crease
2. Or 5mm ulnar to interthenar depression and extend distally in line with 3rd
web space (MacKinnon) – PCN lies 5mm radial to this
3. Avoid too ulnar placement – risk palmar cutaneous branch of ulnar nerve,
nerve of Henle (nerve of ulnar artery) and entry into Guyon’s canal
 Kaplan’s cardinal line – apex of thumb-index web toward hook of hamate, parallel
to prox palmar crease
1. Intersection of line with middle finger flexed into palm = recurrent br
2. Deep palmar arch lies deep to cardinal line
3. Superficial palmar arch between cardinal line and prox palmar crease
 Curvilinear incision beginning prox to Kaplans line, 2-3mm ulnar to thenar crease
(remain ulnar to PL or flexed ring finger at distal wrist crease)
 Blunt dissection transversely => visualise TCL
 Antebrachial fascia penetrated with fine artery – median n identified
 Blunt dissection to separate median nerve and TCL
 Sharp division of TCL on ulnar border
 Distal median n and recurrent branch visualised
 Residual fibres divided
 Antebrachial fascia release in prox part of wound
 Tourniquet down – haemostasis
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Skin closure
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Outcomes
 96% patient satisfaction with 84% return to work
 grip strength return to pre-op at 3months and pinch strength at 6 weeks
TCL repair
 Theory
1. to prevent bowstringing: MRI evidence of an increased volume of the
carpal canal and volar migration of the median nerve and flexor
tendons after release
2. to improve excursion of flexor tendons: D Netscher PRS 1997 Postoperative grip and pinch strength values for the transposition flap
repair group surpassed those of the other two groups at 12 weeks
3. reduce pillar pain, tranverse arch widening
 Best indicated for RA, during concomitant tendon repairs, and CTS release in
conjunction with trigger release/Dupuytren’s
 has been associated with reformation of the carpal tunnel and the subsequent
recurrence of symptoms.
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no benefit demonstrated from neurolysis or epineurotomy
Release of Guyons not recommended as Guyons canal opens up with release of
TCL on MRI
synovectomy not indicated as increases post op haematoma formation + produce
adhesions but indicated for proliferative or invasive tenosynovitis – eg. in gout,
inflammatory arthritis or infection (TB)
Bowers Limited incision
Endoscopic
 30 degree scope used
1. Chow 2 portal technique
o Entry portal – line 1-1.5cm radial to pisiform prox pole + line 0.5cm
prox to end of first line
o 1cm transverse cut from end of 2nd line – thru fascia
o curved dissector/obturator passed to touch hook of hamate
o exit portal – fingers hyperextended, 0.5cm long cut made 1cm prox
along line that bisects angle drawn between distal border of fully
abducted thumb and third web space
o probe knife inserted – cutting distal TCL (distal to prox)
o triangle knife cuts midsection
o retrograde knife pushed from prox to distal to join cuts
o then endoscope inserted distally and process repeated but prox to distal
2. Seiler’s modification of Chow 2 portal technique
o Prox port made just ulnar to PL and distally based fascial flap created
to improve visualisation
o Distal port made before trocar insertion to identify palmar arch
o Trocar inserted along axis of ring finger
o Limited wrist extension (30 deg)
3. Agee single portal endoscopic technique (Agee 3M system)
o 2-3cm transverse cut between FCR and FCU in wrist crease that
separates glabrous palmar skin and wrist skin
o spreading technique until fascia identified
o U shaped distally based forearm fascial flap raised
o probe passed along line of base of 4th finger radial to hook of hamate
o blade assembly inserted with viewing window up against deep surface
of TCL
o palpate and visualise distal border – blade extended and camera
withdrawn – cuts distal 2/3rds
o blade assembly re-inserted and TCL inspected and more cuts to release
remaining fascia
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Post op – splinting for 2 weeks may be detrimental – increase in wound pain in
first month post op
o Not routine but if splint, use for only one week
o Home physio programme of separate finger and wrist exercises
Open vs Endoscopic
 Early studies showed endoscopy had no special benefit in terms of outcome, and
with a substantially increased risk. It was associated with
1. a substantial risk of significant complications including injuries to the median
and ulnar nerves, lacerations of the flexor tendons
2. incomplete release of the carpal tunnel.
o More likely to miss other compressive pathologies – ie synovitis (risk
of recurrence highest in those with bilateral CTS)
 These complications were especially likely to occur where the procedure was only
carried out occasionally.
 Schmelzer PRS Jan 2006 – 753 hands treated with endoscope. 100% symptom
improvement. Complications included one transient median nerve neurapraxia, six
complaints of residual pain, and one complaint of hypersensitivity.
 3 prospective, randomized clinical trials comparing the endoscopic and open
methods
1. Agee (J Hand Surg Am. 1992)
a. higher complications noted with endoscopic
2. Brown et al.( J Bone Joint Surg Am. 1993)
a. independent randomized trial of the two-portal technique, with an 84
day follow-up
b. Authors expressed concern that the endoscopic technique may have a
higher rate of complication
3. Trumble ( J Bone Joint Surg Am. 2002)
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a. independent randomized trial of the 1-port technique of 192 hands in
147 patients, with a 1 year follow-up
b. During the first three months after surgery, the patients treated with the
endoscopic method had better Carpal Tunnel Syndrome Symptom
Severity Scores, better Carpal Tunnel Syndrome Functional Status
Scores, and better subjective satisfaction scores.
c. During the first three months after surgery, they also had significantly
(p < 0.05) greater grip strength, pinch strength, and hand dexterity.
After that, both returned to preoperative levels
d. The open technique resulted in greater scar tenderness during the first
three months after surgery as well as a longer time until the patients
could return to work (median, 38 days compared with 18 days after the
endoscopic release).
e. No technical problems with respect to nerve, tendon, or artery injuries
were noted in either group.
f. There was no significant difference in the rate of complications or the
cost of surgery between the two group
Metanalysis (PRS 2004)
a. endoscopic carpal tunnel release is favored over the open carpal tunnel
release in terms of a reduction in scar tenderness and increase in grip and
pinch strength at a 12-week follow-up.
b. With regard to symptom relief and return to work, the data are
inconclusive.
c. Irreversible nerve damage is uncommon in either technique; however,
there is an increased susceptibility to reversible nerve injury that is three
times as likely to occur with endoscopic carpal tunnel release than with
open carpal tunnel release.
Complications
 3-19%
 Postoperative complications may be classified into the general areas of
neurological, vascular, tendon, and wrist complaints.
Early
1. Hematoma
a. May cause skin necrosis requiring flap coverage
b. Long term increase risk of scarring
2. Nerve damage
a. PCN most common
3.
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6.
b. Recurrent branch
c. Main trunk
d. Ulnar nerve
tendon damage
superficial arch damage
a. pseudoaneurysm
Stiffness
Infection
Late
1. Recurrent symptoms
a. Incomplete division of TCL
b. Extensive scarring – adhesive neuritis
c. Untreated systemic conditions
2. Pillar pain (pain in thenar and or hypothenar area)
3. carpal arch widening
a. direct relationship exists between widening of the transverse carpal arch
and loss of grip strength.
b. Residual pain, forearm circumference, and wrist range of motion are not
related to widening of the transverse carpal arch.
4. Pisotriquetral pain syndrome (J Hand Surg 1989)
a. Hypothenar pain – reported in 1.1%
b. Pain, discomfort, and loss of grip strength mostly during activities
requiring full hand grip or activities associated with use of the heel of the
hand, such as pushing up from a chair, or pushing open a door with the flat
palm.
c. pain from the piso-triquetral joint, possibly a result of intercarpal
alignment change after carpal tunnel release.
d. Pisiform excision curative, with complete relief of symptoms and return of
strength and dexterity.
5. Scar pain
6. Scar
7. Persistent weakness
8. Tendon adhesions, triggering and bowstringing
a. higher frequency of trigger finger noted after carpal tunnel surgery.
b. A possible explanation is that the transverse carpal ligament may also
normally function as the first tendon pulley.
c. When this is released, greater forces are then transmitted to the first
annular ligament, which is now the most proximal pulley and may
contribute to triggering at this site.
9. complex regional pain syndrome
Secondary Surgery
From PRS CME 2001 (Mackinnon)
Aetiology
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Persistent Symptoms - 7- 20% have persistent symptoms following carpal tunnel
release.
1. Most often, the transverse carpal ligament (flexor retinaculum) is incompletely
released, with the problem usually in the most distal portion of the ligament
may also occur more proximally by inadequate release of the most distal
portion of the antebrachial fascia
2. compression of the median nerve further proximally in the forearm or the
neck. There is a well-established association between carpal tunnel syndrome
and cervical disc disease
3. incorrect diagnosis of CTS
Recurrent symptoms
1. Postoperative scarring (common findings at revision surgery)
a. may involve the median nerve directly by forming around it and
entrapping the nerve (adhesive median neuritis, epineural fibrous
fixation, or neurodesis)
b. results in diminished longitudinal excursion of the median nerve,
which has been shown to be approximately 1.0 cm in normal wrists
c. Contributory factors may include hematoma formation, prolonged
postoperative immobilization, or inadequate range-of-motion exercises
and therapy
d. Excess scar tissue may also indirectly affect the nerve by leading to
reformation of the transverse carpal ligament
2. Unmask a more proximal site of compression
New Symptoms - Neurologic injury
1. PCN most commonly
a. incision too radial.
b. abnormal sensation in the territory of the nerve and a Tinel sign at the
level of the injury.
2.
3.
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c. Primary entrapment neuropathy of the palmar cutaneous branch has
been reported - Transection of the transverse carpal ligament may not
release pressure on the palmar cutaneous branch because it may have
its own distinct tunnel to the hand, and postoperative swelling and
edema may lead to compression of this tunnel
d. tender hypertrophic scar is likely to be the result of injury to small
cutaneous branches
Recurrent branch
a. Weakness/atrophy of APB
Median nerve
a. portion of the median nerve to the third webspace is frequently injured
- most superficial or anteriorly located fascicles of the median nerve
b. bowstringing or anterior dislocation of the median nerve rare
Ulnar nerve
a. palmar cutaneous branch, and/or a communicating branch between the
median and ulnar nerves
Complex regional pain syndrome type I
a. rare, but it may follow carpal tunnel surgery or, alternatively, may be
caused or exacerbated by carpal tunnel syndrome.
Multiple factors have been associated with poor results, including
a. injury to the median nerve either from chronic compression or iatrogenic
surgical injury,
b. excessive scar formation preventing the nerve from gliding with wrist
motion
c. subcutaneous atrophy of the palm
d. secondary gain factors (workers compensation)
Clinical
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thorough clinical evaluation, including a complete neurological examination of the
hand and upper extremity, provides an accurate assessment of the status of the
median nerve distally and proximally
Determine if persistent,recurrent or new symptoms
Management
 results following reoperation have been significantly worse, with up to 95 percent
residual symptoms and 40 percent poor results
Secondary external or internal neurolysis
 internal neurolysis - the external and internal epineurium is opened until a normal
fascicular appearance with visible perineurial markings (bands of Fontana) is
seen. Opening the perineurium is avoided because it is an anatomical site of the
blood-nerve barrier.
Release of entrapment of recurrent branch
Neuroma-in-continuity assessment, neuroma management, nerve grafting
 PCN neuroma is neurolysed proximally and buried into muscle
 injury to the main portion of the median nerve itself will usually require an
interposition nerve graft
o thorough preoperative evaluation is vital to provide a good understanding
of the components of the nerve that are uninjured, those that are only
partially injured, and those that are not functioning at all.
o Managed as a Sutherland sixth-degree injury, dissecting and replacing only
the affected portion of the nerve
o Donor nerves
1. first choice - the anterior branch of the medial antebrachial cutaneous
nerve. The landmark for finding the medial antebrachial cutaneous
nerve is the adjacent basilic vein located along the medial border of the
biceps muscle. The anterior branch supplies sensation to the ulnar
volar aspect of the forearm
2. if only short nerve graft needed, the lateral antebrachial cutaneous
nerve may be used instead. It lies adjacent to the cephalic vein along
the medial border of the brachioradialis muscle in the proximal
forearm, and the donor scar is therefore more visible.
3. terminal branch of the anterior interosseous nerve just proximal to the
pronator quadratus muscle. Because it is an expendable motor nerve,
there is no sensory loss.
4. use of the sural nerve for grafting should be reserved for cases in
which long grafts or multiple cable grafting will be needed
The pattern of nerve injury may vary along the length of the nerve and from fascicle
to fascicle at a given level. This illustration of a cross-section of a nerve reveals a
sixth-degree or mixed injury pattern. The fascicle at the 12 o'clock position is normal.
Moving in a clockwise direction, the fascicle at 1 o'clock demonstrates a first-degree
injury (I), or neurapraxia with segmental demyelination. At the 3 o'clock position, a
second-degree injury (II), or axonotmesis, is shown. Injury to the axon, myelin, and
endoneurium, or third-degree injury (III), is demonstrated by the two smaller
fascicles, which are more centrally located. A fourth-degree injury (IV), as shown by
the fascicle at the 9 o'clock position, has marked fibrosis across the nerve, with only
the epineurium remaining intact. At the 5 o'clock position is a fifth-degree injury (V),
which involves transection of the nerve and complete loss of continuity. The surgeon's
role is to identify and reconstruct those fascicles with fourth- and fifth-degree injury
patterns. Those with a first-, second-, or third-degree injury or a normal pattern
should, at most, be neurolysed.
Tissue interposition flaps
 aims to decrease scar adherence of the reoperated median nerve to enhance the
development of new blood vessels, provide padding, and possibly serve as a bed
for nerve regrowth.
 Options
a. local pedicle muscle flaps
 pronator quadratus – difficult dissection but provides better
coverage more proximally in the distal forearm
 abductor digiti minimi (favored by Mackinnon)
 1st and 2nd lumbricals
 palmaris brevis - thin and somewhat variable in its size and
thickness
b. fascial flaps
 reverse radial artery fascial flap – provides little padding
 free thoracodorsal fascial flap
c. fat flaps
 hypothenar fat pad flap (Strickland, J Hand Surg 1996) - limited
in the proximal and distal extent of their coverage, are unable to
cover the median nerve proximal to the wrist flexion crease, and
cannot be placed circumferentially.
d. autologous vein wrapping
 does not provide additional padding to the median nerve, nor
does it enhance vascularity to the area.
e. Regional flaps
 Radial forearm fasciocutaneous/fascial flaps
f. Omental flap (PRS 2005)
 Omentum contains fibroblast growth factor, which has been
shown to stimulate axon growth and nerve regeneration. Its major
use in peripheral nerve surgery is for the treatment of post
radiotherapy brachial plexitis. Fibroblast growth factor has also
been shown to have significant angiogenic potential through its
chemotactic and mitogenic activity in endothelial cells.
 Omentum has also been shown to be advantageous for preventing
perineural fibrosis. Brunelli et al. compared omentum to muscle
regarding its ability to prevent perineural fibrosis and found a
five-fold increase in cicatrix following neurolysis associated with
muscle coverage compared with omentum