Download Median nerve palsy

MEDIAN NERVE PALSY
Aims
1. restore lost motor function – in particular:
a. thumb opposition
b. FPL
c. FDP IF
Classification
1. low – paralysis of abductor pollicis, superficial head of FPB and opponens
pollicis, medial 2 lumbricals
2. High – pronator teres, FCR, FDS, FDP IF/MF, FPL and pronator quadratus
LOW MEDIAN NERVE PALSY
Causes:
1. Infection – polio, leprosy
2. Neurologic – Charcot-Marie-Tooth, spinal muscular atrophy
3. Congenital – absence of thenar muscles
4. Trauma – cervical spine, brachial plexus, lacerations
5. Compression
Thumb Opposition
 Complex movement so that thumb pulp faces the index and long finger pulps –
requires trapeziometacarpal abduction, flexion and pronation
 Retroposition – opposite movement of adduction, extension and supination
 Prime muscle of opposition is APB with some contribution from OP and FPB
 Retroposition is from Adductor pollicis and EPL/EPB
 FPL can act either as an opposer or retroposer, depending on the position of the
limb
 1st CMC is a classic saddle joint where the base of the proximal first phalanx and
the distal surface of the trapezium are reciprocally saddle-shaped.
 concave in the plane of CMC abduction/adduction
 convex in the plane of CMC flexion/extension
 motions allowed at this joint are flexion/extension; abduction/adduction;
opposition/apposition/reposition; and circumduction
 5 stabilising ligaments surround the first CMC (J Hand Surg 1993 Imaeda,
Cooney)
1. deep anterior oblique ligament
a. runs from the volar beak of the metacarpal to the tubercle of the
trapezium.
b. maintains volar stability of saddle joint;
c. help function as a pivot for the first metacarpal during palmar
abduction to allow pronation;
2. posterior oblique ligament
3. ulnar collateral ligament
4. dorsal radial capsular ligament – covered by EPB and EPL, sectioning of
this ligament produces dorsoradial subluxation of the thumb metacarpal;
5. first intermetacarpal ligament




Thumb palmar abduction is needed to grasp larger objects, whereas thumb pinch
function to hold smaller objects requires thumb pronation and short flexor activity
to approximate the thumb pulp to the finger pulps.
Due to the variability of thenar muscle supply, thumb abduction and opposition is
frequently preserved after median nerve injury
 Only 14% of median nerve injuries require opponensplasty
 7% of severe CTS patients require opponensplasty
Brand (in McC) suggests early opposition transfer for high median nerve defects.
The opposition transfer chosen should be one that will not interfere with later
function, usually EIP is taken around the ulnar side of the wrist.
Return of opposition following median n injury depends on the site of the injury.
1. At the wrist: 2/3s of patients will recover opposition
2. At the elbow: 50% will recover opposition but by the time it recovers (usually
about 1 year), rotation may be lost, therefore some advocate early opposition
transfer.
3. In patients with median n palsy, sensory loss may be the single most important
deterrent to satisfactory hand function.
Oppenensplasty
Principles
1. Position takes precedence over force for intact opposition.
2. All soft tissue contractures must be corrected, if necessary by surgery, before
attempting opponensplasty - beware:
o 1st web space contractures
o Contracture of dorsal capsule of 1st CMC joint – limits opposition but not
abduction
3. joints of the thumb especially 1st CMC must be freely mobile and stable
4. appropriate motor muscle, suitable in each case, must be selected.
5. To produce true opposition, it is desirable to construct a pulley, which is fixed
securely, provides correct direction of pull and is at a sufficient distance from
the thumb to permit enough excursion of the transferred tendon.
6. Appropriate insertion
Motor
 Strength of muscle proportional to cross-sectional area – tension fraction
 Excursion determined by muscle fibre length
 Ideal opponensplasty aiming to replace APB and OP
 The greater the potential excursion of the donor, the greater the margin for error in
setting the tension
 Median innervated
1. FDS RF/MF  commonest used (usually through FCU pulley)
2. PL - good for temporary transfer while awaiting recovery of high median n
injury (Camitz)
3. FPL -can use whole or half of tendon (Steindler)
4. FCR
 Ulnar innervated
1. ADM  commonly used for congenital problems (Huber, Littler)
2. FCU
 Radial innervated
1. EIP  also commonly used. Either around ulnar border of wrist or through
interosseus membrane.
2. ECRL
3. ECRB
4. ECU
5. EPL
6. EDM
7. EIP
8. APL
Pulley
 best restored by transfer that runs subcutaneously across the palm parallel to the
abductor pollicus brevis tendon and thus all good extrinsic opponensplasties must
run around a stout fixed pulley in the region of the pisiform (Bunnell)
 at pisiform, produces maximal thumb abduction and opposition but only small
amount of flexion at MCPJ
 distal to pisiform gives more flexion but less abduction – distal pulleys may be
better for combined median/ulnar nerve palsy
1. Ulnar border of wrist – extensors usually
2. FCU tendon just proximal to pisiform
 Proximal migration of the transferred tendon, owing to a lack of a fixed
pulley, can occur.
 Bunnell uses a loop of FCU as the proximal tendon pulley - pulley is
created using approximately 3 to 4 cm of a distally based strip made of one
half of the FCU tendon
3. Around pisiform
4. Guyons canal
5. Carpal tunnel
 Royle-Thompson method uses a pulley consisting of the distal end of the
transverse carpal ligament and the ulnar border of the palmar aponeurosis.







Camitz transfer does not use a pulley - produces a more longitudinally oriented
line of pull that is parallel to the forearm
Carpal tunnel or Guyon's canal pulleys give more transversely orientated lines of
pull
Around-FCU and FCU loop transfers produce a line of pull somewhere between
these other transfer routes
A more proximal pulley location (FCU loop) or a transfer with a more radially
directed line of pull (around FCU, Camitz) produced more thumb abduction than
the distally placed proximal pulleys (Royle-Thompson and Guyon's).
The Camitz transfer produced as much palmar abduction as the other pulleys. If
the main function of the tendon transfer is thumb palmar abduction alone, a more
proximally based pulley or a Camitz transfer appears to be a reasonable option.
A more distally placed pulley produces more approximation of the thumb to the
fifth metacarpal head. Approximation of the thumb tip to the fifth metacarpal head
was the greatest with the Royle-Thompson and Guyon's canal proximal pulleys,
least for the Camitz transfer, and intermediate for the around-FCU and FCU loop
pulleys.
The distally based pulleys have a line of transfer directed more transversely across
the palm, thereby producing more thumb tip approximation to the fifth metacarpal
head.
Insertion
 May be single or dual
 Dual insertions aim to undertake 2 functions – ie active opposition and passive
stabilization of the MP joints or restriction of the IP joint flexion (beneficial in
combined ulnar/median nerve palsies)
 Pronation does not need to be recreated as this occurs passively after abduction
and flexion
 palmar radial insertions produces greater thumb opposition and better pulp to pulp
positioning of the thumb to the fingers than the dorsal ulnar insertion.
 In 1 biomechanical study, FPB combined with radial dorsal extensor hood site;
and the APB insertion site allowed the closest approximation of normal thumb
opposition.
1. abductor pollicis brevis insertion
 most popular insertion
2. APB + EPL
 Increases power of extension of the interphalangeal joint of the thumb
 In those without FPL, a hyperextension deformity can result.
3. APB+EPL+adductor pollucis (Brand)
 creates considerable stability in the MP joint.
4. FPB + dorsal radial extensor hood
5. ulnar extensor hood
6. EPB/FPL insertions – reserved for complex cases
7. dorso-ulnar aspect of base of proximal phalanx (Bunnell)
8. metacarpal neck
Superficialis Opponensplasty
Motor
 FDS RF or MF
o Incisions
1. longitudinal incision, radial base of hypothenar
2. transverse incision at finger crease for distal tendon
3. incision dorsum of thumb MPJ
o Beware
1. flexion contracture PIPJ – division at insertion destroys vincula to FDP
+ surgical trauma around PIPJ capsule
2. Swan neck deformity in supple joints (Asians)
3. DIPJ extension lag – lateral band adhesions
o Divide between A1 and A2 with finger fully flexed leaving 3cm stump
(either leave free or suture to volar plate)
Pulley
1. Around FCU pulley – fallen out of favor due to proximal migration
2. FCU pulley – distally based half of FCU attached to pisiform (Bunnell) or ECU
3. Angle between distal edge of TCL and ulnar border of palmar aponeurosis
(Thompson-Royle)
4. Guyons canal
Insertion
1. APB
2. one slip to neck of thumb metacarpus (radio to ulnar), second slip to over the
extensors and into the base of proximal phalanx (Thompson)
3. superficial head of the flexor pollicis brevis and the opponens pollicis (Royle)
4. base of proximal phalanx dorsoulnar to radiopalmar
May be complicated by PIPJ contracture of donor finger – thought to be due to
dissection around the PIPJ/volar plate (avoid by dividing tendon proximal to
decussation between A1 and A2 pulleys.
EIP Opponensplasty (Burkhalter)
Motor
 EIP
o Good motor for high median nerve palsy
o Does not weaken grip and causes no functional disability unlike FDS
o Incisions
1. Longitudinal incision over 2nd MPJ
2. Distal forearm, dorsoulnar aspect
3. Over the pisiform
4. incision dorsum of thumb MPJ
Pulley
o pisiform
o ensure EIP goes superficial to FCU to prevent compression of ulnar nerve
Insertion
1. APB (isolated median nerve)
2. APB, MPJ capsule and EPL over proximal phalanx (Riordan) – best for combined
median and ulnar
Abductor Digiti Minimi Opponensplaty (Huber)
Motor
 ADM
 Improves hand appearance by adding bulk to thenar eminence
 Incisions:
1. mid lateral incision over ulnar border of little finger proximal phalanx to
radial border of hypothenar curving ulnarward as it crosses the wrist
a. divide insertion into proximal phalanx and dorsal expansion and
mobilize muscle towards pisiform
b. protect neurovascular bundle – dorsoradial aspect
c. increase length by raising off pisiform maintaining attachments to
FCU – this may devascularise the muscle so some leave it on
pisiform and extend it with a tendon graft
2. Dorsoradial incision over 1st MCPJ
Pulley
 None – direct line of pull
Insertion
 APB – will just reach this under some tension if no graft is used
Palmaris Longus Opponensplaty (Camitz)
Motor
 Palmaris Longus
 Best used for loss of abduction/opposition after severe CTS
 Can be performed at the same time as CTR
 Restores abduction rather than opposition
 May be done while awaiting for recovery of thenar muscles post release
 Not recommended for traumatic nerve injuries as PL overlies the nerve and is
usually damaged
 Incision
1. 2cm proximal to distal wrist crease to proximal palmar crease in line with
4th finger.
 Tendon dissected with 1cm wide strip of palmar aponeurosis
2. dorsoradial 1st MCPJ incision
Pulley
 None
 Others have suggested using pisiform (Bunnell) or through a window in the flexor
retinaculum
Insertion
 APB
 EPB or dorsal capsule of MCPJ – may give more opposition
Extensor Carpi Ulnaris Opponensplaty (Phalen)
Motor
 ECU
o Joined to EPB which is divided proximally at the musculotendinous
junction
o May cause radial wrist deviation – weakens grip
o Incision
1. dorsoradial border distal forearm
o EPB divided
2. dorsal aspect of 1st MPJ
o EPB passed to wrist around pisiform
3. L incision ulnar border of wrist
o ECU divided at insertion and passed around ulnar border of
forearm
o Problems
1. EPB sometimes nonexistent
2. MPJ flexion deformity if dissected right out to insertion or if not far
enough distally – hyperextension
3. There may be a tendinous slip between EPL and EPB that requires
division
Pulley
 Pisiform
Insertion
 EPB
ECRL Opponensplasty
Motor
 ECRL
o requires tendon grafting or EPL
o Incisions
1. over 3rd dorsal compartment
 EPL divided and tunneled across palm towards ulnar styloid and
sutured to ECRL
2. dorsal 1st MCPJ incision
3. ulnar styloid
Pulley
 Ulnar border
Insertion
 EPL
EDM Opponensplasty
Motor
 EDM
o requires tendon grafting or EPL
o Incisions
1. dorsum LF MCPJ
 EDM (2 slips) harvested with central slip divided and mobilized to
distal third forearm
 Passed around ulnar border like EIP transfer
2. dorsal 1st MCPJ incision
3. pisiform
Pulley
 Ulnar border
Insertion
 APB, extensor expansion and EPL
Opponensplasty for severe nerve deficits

Combined low median and ulnar nerve injuries
o Hyperflexion of thumb IPJ and hyperextension of MCPJ
o Can only use key pinch
o Tip pinch will occur with IF pulp pinching down on thumb nail causing
thumb supination (crank handle effect)
FPL Opponensplasty
Motor
 FPL
o For patients with complete intrinsic minus hand who need strong lateral
grip to sides of IF/MF and where pulp pinch is less important
o IPJ fused in extension
o Incisions
1. Brunner over thumb IPJ
 FPL divided
2. Distal wrist incision
 FPL retrieved and passed round pulley
3. pisiform
Pulley
 Pisiform or FCU or Royle-Thompson
Insertion
 Superficial head of FPB – allows more MCPJ stability
Variation
 FPL not divided but thumb proximal phalanx is osteotomised and tendon is
looped around the proximal phalanx
 Otherwise pass thru IPJ or MCPJ which is then fused.
EPL Opponensplasty
Motor
 EPL
o For patients with only EPL, EPB and APL functioning with IPJ flexion
deformity (due to extensors acting to hyperextend MCPJ)
o IPJ fused in extension
o Thumb extension will have to depend on APL and EPB
o Retroposition will be reduced
o Incisions
1. Dorsal thumb incision
 EPL divided
 MP joint fused in extension and slight pronation
2. 3rd compartment incision
 EPL retrieved and passed round ulnar border
3. pisiform
Pulley
 Pisiform or FCU or Royle-Thompson
Insertion
 Sutured to extensor expansion at MCPJ
Variation
 Other pulleys used – interosseous membrane and then around FCR (isolated
median nerve injury) or FCU (combined median/ulnar)
Methods of assessing opponensplasty
Kapandji Index (Ann Chir Main 1986)
 opposition test consists of touching the four long fingers with the tip of the thumb:
the score is:
 1 for the lateral side of the second phalanx of the index finger
 2 for the lateral side of the third phalanx
 3 for the tip of the index finger
 4 for the tip of the middle finger
 5 for the ring finger
 6 for the little finger.
 Then, moving the thumb proximally along the volar aspect of the little finger, the
score is 7 when it touches the DIP crease
 8 on the PIP crease
 9 on the proximal crease of the little finger
 10 when it reaches the distal volar crease of the hand
 test is valid only if the first stages are possible: a crawling thumb in the palm is
not an opposition motion.
HIGH MEDIAN NERVE INJURY
Aim:
1. restore flexion of IF and thumb
2. restore opposition
Potential donors
1. Brachioradialis
2. ECRL
3. ECU
4. EIP
Timing


Sensory deficit probably the most important single disability
 Dramatically reduces the functional benefit of tendon transfers
Consider early transfers for opposition
Restore Opposition
Donors
1. ECU
2. EIP
3. EDM
4. Ulnar flexors (FCU) not recommended as they will further weaken flexion
Restore Pronation
1. Biceps re-routed around the radius (Zancolli). Better because it also weakens
supination.
2. ECU around ulna border to the thumb metacarpus
Restore Profundus
 End to side repair of ulnar profundi to paralysed radial tendons (does not restore
power)
 If need power to IF and are unlikely to obtain significant reinnervation following
neurorrhaphy, then consider ECRL to IF profundus
 Swan neck deformities may occur with long term median nerve paralysis due to
extension forces on PIPJ volar plate. Options:
1. transfer ECRL to FDS IF/MF and use profundus to tenodese DIPJ
2. ECRL to profundus and suture profundus to A4 pulley
3. ECRL to profundus and fuse DIPJ
Restore FPL
 Brachioradialis commonly used
 Must be freed of all soft rissue and fascial attachments throughout the distal 2/3rd
Extrinsic replacement using the brachioradialis to the flexor pollicis longus (A) and
the extensor carpi radialis longus to the profundi of the index and long fingers (B). In
both situations, the transfers as shown are end-to-end. If the patient has any chance of
extrinsic return following grafting, the transfer should be end-to-side