ulnar nerve entrapment

Cubital tunnel syndrome

definition

· symptoms and signs from entrapment of ulnar nerve near elbow

aetiology

Compression

Cubital tunnel

· fibro-osseous ring

· formed by

· medial epicondyle

· fascial sheet

Arcade of Struthers

· thick fascial band

· 8 cm proximal to medial epicondyle

· runs from medial head of triceps to medial intermuscular septum

· compression where nerve passes from anterior to posterior compartment of arm

Arcade of Osborne

· aponeurosis joining heads of FCU

Other factors

· subluxation of nerve across epicondyle

· osteoarthritis

· osteophytes in tunnel

· elbow fractures

· lateral condyle with valgus deformity

· medial condyle with callus

· cysts or ganglia in tunnel

· prolonged or repeated elbow flexion

· musicians

· tennis players

clinical features

History

· pain on ulnar side of elbow

· pain and parasthesiae in ulnar hand and fingers

· provoked by elbow flexion

· clumsiness

· weakness of fine movements

Examination

· tenderness and swelling of ulnar nerve at entrance to tunnel

· positive Tinel’s sign at elbow

· decreased sensation in ulnar palm and fingers

· decreased sensation of ulnar dorsum

· skin changes of denervation

· wasting of hypothenar eminence and intrinsics

· weakness of intrinsics

· ulnar claw hand

· Wadsworth’s test

· reproduction of symptoms with forced elbow flexion and supination

investigations

X-ray

· of elbow

· routine views

· cubital tunnel view

Electrodiagnostic studies

· slowed conduction across elbow

· fibrillation potentials in hypothenar muscles

differential diagnosis

Cervical radiculopathy

· neck and shoulder pain

· headaches

· restricted neck ROM

Thoracic outlet syndrome

· neck and shoulder pain

· aggravated by overhead activity

Ulnar tunnel syndrome

· no numbness in palmar or dorsal branch distribution

· no forearm weakness

· no Tinel’s sign at elbow

Other

· Pancoast tumour at lung apex

· intraspinal pathology (eg. syrinx)

· polyneuropathy (eg. diabetes)

treatment

Nonoperative

· 50% resolve

· splintage

· night elbow-extension splint

Operative

Decompression

Indications

· simple compression

Advantages

· simple

· safe

Disadvantages

· not always effective

· space-occupying lesions

· subluxing nerve

· recurrence in advanced cases

Technique

· incision centred over cubital tunnel

· halfway between olecranon and medial epicondyle

· extended proximally along medial edge of triceps and distally parallel to border of ulna

· branches of medial cutaneous nerve of forearm preserved

· deepened through deep fascia

· nerve identified in proximal tunnel

· fibrous band of FCU divided

· decompression extended

· proximally to medial intermuscular septum

· distally to muscular part of FCU

Transposition

Indications

· subluxation

· valgus deformity

· failed decompression

Advantages

· allows functional lengthening of nerve

· low recurrence rate

Disadvantages

· branches at risk

· scar formation

· possible new proximal site of compression

· interference with flexor muscles

Technique

· incision as above

· dissection as above proximally and distally

· care taken to protect muscular branches

· 2 branches to FCU

· branch to profundus

· nerve elevated from bed with accompanying vessels

· three options

1. submuscular

· muscles elevated from medial epicondyle

· nerve transposed anteriorly

· muscles reattached

2. intramuscular

· 5 mm trough made in surface of muscles

· nerve transposed into groove

· superficial fascia closed over nerve

3. subcutaneous

· new sling fashioned from superficial fascia

· nerve transposed anterior to it

· edge of sling sutured to dermis

· care to avoid compression

· at medial intermuscular septum

· by repaired muscles

· between heads of FCU

Medial epicondylectomy

Indications

· valgus deformity

· malunited fracture

Advantages

· nerve not disturbed

Disadvantages

· produces scarring

· protection of medial epicondyle lost

· site of compression not identified

Technique

· incision centred on posterior aspect of medial epicondyle

· common flexor origin elevated

· nerve identified and protected

· medial condyle and supracondylar ridge removed

· guide is medial border of trochlea

· flexor origin attached to periosteum

Ulnar tunnel syndrome

definition

· symptoms and signs from compression of ulnar nerve in Guyon’s canal

aetiology

· repeated blunt trauma (esp. occupational)

· ganglion or lipoma in Guyon’s canal

· fractures of hamate or triquetrum

clinical features

History

· pain and parasthesiae in ulnar hand and fingers

Examination

· decreased sensation in ulnar palm and fingers

· sensory changes on dorsum suggest higher lesion

· skin changes of denervation

· wasting of hypothenar eminence and intrinsics

· weakness of intrinsics

· ulnar claw hand

treatment

Operative

· incision on radial border of FCU

· 3 cm proximal to wrist crease

· across crease

· along line of ring finger

· ulnar nerve isolated above wrist

· followed into Guyon’s canal

· opening of canal by ulnar reflection of

· FCU

· pisiform

· pisohamate ligament