ULNAR NERVE ANATOMY & LESIONS

Dr SUBHAKANTA MOHAPATRA IPGME&R,Kolkata,INDIA

ANATOMY OF ULNAR NERVE

A branch of medial cord of the brachial plexus (C8 & T1). Additional fibers from C7.

Axilla : between axillary vein & artery on a deeper plane.

runs downwards with proximal part of brachial artery.

at middle of humerus pierces medial intermuscular septum.

descends behind medial epicondyle.

Forearm : enters by passing between two heads of FCU.

lies on medial part of FDP. accompanied by ulnar artery in lower 2/3 rd.

After it travels down the ulna, the ulnar nerve enters the palm of the hand.

At the wrist, the ulnar nerve and artery lie in a canal formed by the pisiform bone medially and the hook of hamate laterally (Guyon’s canal). In this region the nerve divides into two branches. The Superficial sensory Branch The Deep Motor Branch

The superficial branch is generally considered a

sensory branch which supplies to distal palm, fifth and half of the fourth digit.

It also supplies palmaris brevis, a thin muscle beneath the skin which cannot be studied electromyographically.

The deep branch gives off motor innervation to the hand muscles.

WRIST TO (MEDIAL) HAND

BRANCHES:Muscular FCU, FDP (medial half), palmaris brevis,

hypothenar muscles, medial 2 lumbricals, all palmar & dorsal interossei , thumb intrinsics medial to FPL {adductor pollicis , flexor pollicis brevis (deep head)}

Cutaneous palmar cutaneous supply to hypothenar

eminence Dorsal cutaneous supply dorsum of hand (medial

part), dorsum of little finger , part of dorsum of ring finger.

Digital forms the main sensory branches to the ring and

little fingerVascular & ArticularNo branches above elbow

DORSAL CUTANEOUS BRANCH

PALMAR CUTANEOUS BRANCH

ETIOLOGY OF ULNAR NERVE PALSY Injuries

Primary neurologic diseases

Leprosy

Compression neuropathies

CHARACTERISTICS OF PALSY

INJURIES- proximal : motor - all muscles affected.

sensory - palmar & dorsal aspects of medial third of hand, whole of little finger & ulnar half of ring finger.

distal : motor - only intrinsic muscles involved

sensory - medial third of palm, palmar & dorsal (distal to PIP joint) aspects of little & ulnar half of ring finger

Injury to terminal deep branch in palm Motor: spares hypothenar muscle Sensory: sensation in ring & little finger preserved.Compression in distal portion of guyon’s canal Sensation (ring & little) intact Loss of function of all ulnar innervated intrinsic &

hypothenar muscles.In proximal portion of guyon’s canal Preserved sensation over dorsal ulnar aspect of

hand. (by dorsal branch of ulnar nerve which arises in

distal forearm & perforates the deep fascia 6-8 cm proximal to wrist)

LEPROSY sensory changes precede motor paralysis POLIOMYELITIS LMN type flaccid paralysis

CLINICAL FEATURES Claw deformity . more apparent during use than at rest more in mobile & lax fingers When gripping an object , object is pushed out of

the palm (in order of DIP, PIP, MP joint flexion) Wasting of hypothenar region & shallow mid-

palmar receptacle. Longitudinal palmar furrows between long flexor

tendons. Wasting of dorsum, with shallow concavities in

inter-metacarpal spaces & thumb web. Shape of hand - Isosceles triangle with base

distally. Loss of sensation is not as devastating as

compared to median nerve palsy.

ASSESSMENT OF MOTOR FUNCTION

Duchenne’s sign : claw deformity of fingers ; ulnar paradox

Bouvier’s maneuver: active extension of middle & distal phalanges on passive dorsal pressure on proximal phalanx.

Andre-Thomas sign : increased clawing on attempted extension of fingers by flexing wrist.

Pitres-Testut sign : inability to abduct extended middle finger to radial & ulnar sides(2nd &3rd DI)

Cross your fingers test: Inability to cross the middle finger dorsally over the index finger or vise versa.(1st PI & 2nd DI)

Asynchronous finger flexion

Fingers curl or roll into palm & inefficient grasp

Jeanne’s sign : Hyperextension of MP joint of thumb during key pinch(to compensate thumb adductors)

Masse’s sign : flattened metacarpal arch & loss of hypothenar elevation

Froment’s sign : hyperflexion of IP jt of thumb while attempting a lateral pinch(indicates paralysis of adductor pollicis, 1st DI , with replacement of pinch function by FPL)

Bunnell’s O sign : hyper extension of MP jt & hyper flexion of IP jt

Wartenberg’s sign: inability to adduct extended little finger to touch the extended ring finger(loss of function of 3rd PI & unopposed abduction of EDM).

Pollock’s sign : inability to flex DIP jt of ring & little fingers while making a fist

Partial loss of wrist flexion with inability to perform power grip : Bowden & Napier

ASSESSMENT OF SENSORY FUNCTION Static two point discrimination test (6 mm is

normal) for tactile perception. Dynamic two point discrimination test (3 mm

is normal). Semmes – Weinstein monofilament (of

various diameters) for pressure perception. Tune fork 250 cps (pacinian corpuscles) , 30

cps (meissner corpuscles) for vibration perception.

Cold heat test (10 degree, 40 degree water) for free nerve endings of the skin.

Ten test (0- 10 ranking of quality of sensation)

ANOMALOUS INNERVATION PATTERNS May contain axons from C7 & T2 roots. Motor axons to FCU may arise from C7 root. FDP innervation may be all ulnar/ all median/

combined. Martin-Gruber anomalous motor connections in

proximal forearm between median(AIN) & ulnar nerve.

Riche-Cannieu anomalous connections in hand, resulting in all lumbricals supplied by median nerve & no clawing even after complete ulnar nerve injury.

Ring finger lumbrical dual supply in 50%. 1st dorsal interosseous supplied by median nerve

in 10% & radial nerve in 1%. Area supplied by dorsal sensory branch may be

innervated by superficial branch of radial nerve.

MANAGEMENTACUTE INJURIES

Closed

Localize clinically

Follow-up with EMG & NCS

Recovery No recovery

Observe surgery

Open

Surgery

Nerve in continuity not in continuity

As closed injury sharp crush

repairapproxi

mate

Graft

GOALS OF SURGERY To improve function rather than restore normal

function To improve thumb pinch To correct finger clawing To restore the normal pattern of finger flexion To restore ring & little finger DIP joint flexion

in high ulnar nerve palsy. To restore sensation to ring & little

finger(possible but not attempted) To restore the concavity of the transverse

metacarpal arch & correct little finger abduction deformity.

PRINCIPLES OF NERVE REPAIR Contused or attenuated nerve usually left

intact. Resection of unhealthy fascicles in nerve ends

should not be compromised to preserve length. Tension free repair with good alignment of

fascicles Mobilisation of 1-2 cm to allow repair Trimming of fascicles & loose epineural sutures

to prevent buckle Nerve grafting is preferable to avoid tension Ends are tagged by prolene 6-0 if staged repair

is planned.

INTERNAL TOPOGRAPHY At mid forearm - Three distinct fascicular group(dorsal sensory,

volar sensory,motor group). Motor group positioned between ulnar dorsal

sensory & radial volar sensory group. Dorsal sensory group separates from the main

nerve approx 8 cm proximal to wrist. Motor group remains ulnar to the volar sensory

group until the guyon’s canal, then it passes dorsally & radially to become the deep motor branch to the intrinsic muscles.

ULNAR NERVE TOPOGRAPHY

LATE DEFORMITIES & DEFICIENCIES

Claw finger: static techniques - Only if passive flexion of MP joint results in

extension of PIP.• Zancolli’s palmar capsulodesis of MCP

joint• Omer’s modification of Zancolli technique• Tenodesis- Parkes(PL & Plantaris)

Fowler (tendon graft sutured to ER)

Riordan( ECRL & ECU )

DYNAMIC TENDON TRANSFERS

Stiles & Bunnell – Both slips of all the superficialis tendon transfered to both radial & ulnar lateral bands of extensor mechanism.

Modified Stiles & Bunnell- FDS of middle finger Fowler’s technique – EIP & EDM transfer Modified Fowler – EIP transfer (2 slips) Dorsal route transfer of ECRL/ECRB Flexor route transfer of ECRL (through the

carpal tunnel) PL 4 tail transfer

Ulnar deviation of little finger:

• EDM transfer

Flexion-adduction of thumb :

• Littler-Ring finger superficialis• Smith-ECRB as motor

Z-thumb:

• Split FPL-EPL transfer tenodesis• MP & IP jt arthrodesis

Index finger abduction:

• Bunnell-EI• Bruner- EPB• Neviaser- accessory APL elongated by tendon

graft

High ulnar palsy-• tenorrhaphy• FCR to FCU

Restoration of transverse metacarpal arch Bunnell’s tendon T operation

A detached FDS attached to middle of a free tendon graft, one end of graft inserted to base of proximal phalanx, other to little finger metacarpal neck.

Restoration of sensibility:Lewis’ digital nerve transfer

Wasted intermetacarpal spaces:Dermal graft placement

MANAGEMENT IN LEPROSY

• MDT • Surgery- acute- decompression in severe pain abscess drainage in neuritis quiescent- reconstructions after stopping

steroids.

Management in case of poliomyelitis Surgery delayed till child is 5 years of age

Cubital tunnel syndrome: Early- conservative for 3 months Static elbow extension splint Simple unroofing of cubital tunnel is not

recommended.Submuscular anterior transposition(so

that elbow flexion relaxes rather stretches the nerve)

& avoiding injury to the medial antebrachial cutaneous nerve to forearm.

Treatment of Guyon’s tunnel syndrome:

Decompression by incising along radial border of FCU

(avoiding injury to dorsal branch of ulnar nerve which does not pass through this canal)

Dissecting from distal to proximal along ulnar artery branches to ring & small fingers, progressively unroofing & deroofing the guyon canal is more safer.

THANK YOU