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Ulna Nerve neuropathies Flashcards

1
Q

Describe the anatomy/ course of the ulna nerve?

A
  • From medial cord of brachial plexus C8- T1
  • Arm
    • Lies posteriomedial to Brachial artery-in ant compartment - upper arm
    • Pierces Intramuscular sceptm at Arcade of Struthers
      • 8cm from medial epicondyle & medial to triceps
      • Arcade = band of aponeurotic band from medial im septum to medial head of triceps
  • Elbow
    • Runs behind medial epicondyle with Superior ulna collateral artery
    • Cubital tunnel= roof - Osborne’s ligament ( fascia extension from 2 heads of FCU, and aponeurosis distally. floor = transverse and posterior bands of MCL
  • Forearm
    • 2 heads of FCU
    • FCU and FDP
  • Wrist
    • Ulna nerve and Artery pass SUPERFICIAL to transverse carpal ligament
    • Bificates into sensory and motor at Gyon’s canal
    • Gyon canal
      • roof - volar carpal ligament
      • floor transverse carpal ligament, hypothenar muscles,
      • ulna border- pisiform, psihamate ligaments, abductor digiti minimi-
      • radial border- hook of hamate
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2
Q

Describe the motor supply of ulna nerve?

A
  • Forearm
    • FCU
    • FDP 3/4 - Ring and little
  • Thenar
    • Adductor pollicis
    • Deep head of flexor pollicis brevis
  • Fingers
    • Interossei- palmar
    • 3rd/4th lumbricals
  • Hypothenar muscle
    • abductor digit minimi
    • opponens digiti minimi
    • flexor digiti minimi
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3
Q

What is Cubital Tunnel syndrome?

A
  • A compressive neuropathy of the ulna nerve
  • 2nd most common neuropathy
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4
Q

Describe the sites of entrapment?

A
  • Between 2 heads of FCU - most common
  • Arcade of Struthers
  • Between Osborne’s ligament
  • “FAO”
  • less common
    • Medial head of triceps
    • medial intermuscualr septum]
    • medial epicondyle
    • Fascial bands within FCU
    • Aconeus epitrochlearis
  • External sources
    • fracture and medial epicondyle non unions
    • osteophytes
    • heterotrophic ossification
    • tumour and ganglionic cysts
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5
Q

Name any associated conditions of cubital tunnel syndrome?

A
  • Cubitus varus/ vlagus
  • Medial epicondylitis
  • Burns
  • Elbow contracture release
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6
Q

Describe the signs and symptoms of cubital tunnel syndrome?

A

Symptoms

  • Parathesia of 1/2 of ring finger, small finger and ulnar dorsal hand
  • Night symptoms- caused by sleeping arm in flexion

Signs

  • Interosseous and First Web Space atrophy
  • Ring and Small finger Clawing
  • Ulna nerve subluxing over medial epicondyle during arm of movement in elbow
  • Decrease sensation small, 1/2 ring fingers
  • Motor
    • Loss of ulna n- loss of inrinsics- interossei, lumbricals 4/5, Adductor pollicis
    • Weakness gasp- Loss of MP joint flexion power
    • Weak Pinch- loss of adductor pollicis- approx 70% strength lost
    • Fromens sign- conpensatory flexion at IPJ by FPL due to loss of MCPJ flexion by adductor pollicis
    • Jeannes sign- with key pinch- compensatory MCPJ hyperextension and thumb adduction by EPL due to loss of Adductor pollicis ( flexes MCPJ, Extends IPJ and adducts thumb)
    • Warternberg’s sign- Persistent 5th MC abduction & extension during attempted adduction of finger- weak 3rd palmar interossei & small finger lumbrical.
    • Pollock’s test- weakness of 2 ulnar FDP
    • Tinels postive over cubital tunnel
    • Elbow flexion test- postive if symptoms start w elbow flexion >60 seconds
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7
Q

Describe investigations useful to identify cubital tunnel syndrome?

A

EMG/NCV

  • useful in diagnosis/prognosis
  • Ulna nerve conduction velocity <50m/s across elbow
  • reduction in amplitude for sensory n action potential and motor n action potential
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8
Q

Decribe the Tx for cubital tunnel syndrome?

A

Non operative

  • Nsaids, activity modification, & night time elbow splinting
    • splinting =45o of extension , neutral rotation at night
    • effective in 50% cases

Operative

  • Insitu ulna nerve decompresion without transposition
    • When non op fails before motor function results
    • Open release of cubital tunnel retinaculum
    • arthroscopic release- favourable early data but no long term data
    • Similar results with less complications cf transposition of nerve
    • 80-90% gf results if denervation hasn’t occurred
    • Poor prognosis associated with intrinsic Muscle Atrophy
  • Ulna nerve decompression and anterior transposition
    • failed insitu release/throwing athelete,pt with poor ulna bed from tumour/osteophyte
    • Subcutaneous, Submuscular, or intramuscular TRANSPOSITION of nerve
    • similar outcomes to insitu release but can cause new site of compression
  • medial epicondylectomy
    • Visible and subluxing ulna nerve
    • Insitu release with medial epicondylectomy
    • risk of destabilising elbow by damaging medical Ulnar Collateral ligament
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9
Q

what are the complications of cubital tunnel syndrome?

A
  • Reocurrance - due to incomplete release. perineural scarring, or tethering of intermuscular septum of FCU fascia
  • Neuroma formation-iatrogenic injury to medial antebrachial cutaneous branch of ulna nerve-> persistent posteriomedial elbow pain.
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10
Q

What is Ulnar tunnel syndrome?

A
  • Ulnar nerve neuropathy caused by direct compressionin Guyon’s canal
  • Aka Handlebar palsy- seen in cyclist
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11
Q

Describe the pathoantomy of ulnar tunnel syndrome?

A

cause of compression include:

  • ganglion cyst
  • lipoma
  • ulnar artery thrombosis/ aneurysm
  • Hook of hamate fracture
  • Pisiform dislocation
  • Inflammatory athritis
  • Fibrous band / bony anamaly
  • Congential bands
  • Palmaris brevis bypertrophy
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12
Q

Describe the anatomy of Guyon’s canal?

A
  • 4cm long
  • begins at proximal extent of transverse carpal ligament
  • Ends at aponeurotic arch of hypothenar muscle
  • Ulna n branches into SUPERFICIAL SENSORY and DEEP MOTOR
  • Floor= Transverse carpal ligament, hypothenar muscle
  • Roof= Volar carpal ligament
  • Ulnar border= Pisiform & psiohamate ligament, abductor digit minimi muscle belly
  • radial border= hook of hamate
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13
Q

Describe the Zones of Guyon’s canal?

A
  • Zone 1- Proximal bifurcation of nerve
    • Ganglia and Hook of hamate fr= compression
    • Mixed Motor and Sensory symptoms
  • Zone 2- Surrounds deep motor branch
    • Ganglia and hook of hamate fractures= comp
    • Motor only symptoms
  • Zone 3- Surrounds superficial sensory branch
    • Ulnar artery thrombosis / aneurysm
    • Sensory symptoms only
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14
Q

What does the deep motor branch supply?

A
  • All interossei and 3/4 lumbrical
  • Hypothenar muscles- abductor digit minimi, Flexor digit minimi brevis, opponens digiti minimi, palmaris brevis
  • Adductor pollicis
  • Medial head ( deep) flexor pollicis brevis
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15
Q

Describe the signs and symptoms of ulnar tunnel syndrome?

A

Presentation depends on location of compression within Guyon’s canal and maybe

  • Pure motor/ Pure Sensory/ Mixed sensory/motor
  • Ulna n palsy -> paralysis of intrinsics (adductor pollicis, deep head of FPB, interossei, Lumbricals 4/5)

Symptoms

  • Pain and parathesisa in ulnar 1-2 digits

O/E

  • Clawing of ring and little fingers
    • Loss of Intrinsics flexing the MCPs /extending IPJ
  • Allen’s test - helps dx ulnar artery thrombosis
  • Weakened Gasp- loss MCPJ flexion power
  • Weak Pinch- loss thumb adduction ( AP)
  • Froment sign- IP flexion compensates for loss of thumb adduction when attempting to hold peice of paper. IP Hyperflexion by FPL ( AIN)
  • Wartenberg sign- adduction posturing of little finger
  • Jeane’s sign- compensatory thumb MC hyperextension & thumb adduction by EPL. compensates for loss of IP extension and thumb adduction by adductor pollicis ( Ulnar)
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16
Q

What investigations are useful for DX of ulnar tunnel syndrome?

A
  • Xrays- identify hook of hamate fractures
  • CT= identify hook of hamate fractures
  • MRI= ganglionic cyst, gradient echo to see ulnar artery aneurysm
  • Doppler= useful for thrombosis/aneurysm
17
Q

How to ddx from ulnar tunnel syndrome from cubital tunnel syndrome?

A

Cubital tunnel demonstrates

  • Less clawing
  • Sensory Deficit to DORSUM of Hand- dorsal cutaneous branches proximal to Guyon’s canal
  • Motor deficit ro ULNAR- INNERVATED extrinisics muscle
  • Tinels sign at the ELBOW
  • positive elbow flexion test
18
Q

What is the TX of ulnar tunnel syndrome?

A

Non operative

  • Activity modification, NSAIDs, Spinting

Operative

  • Local decompression- severe symptoms/ failed consx
  • tendon transfers
    • correction clawed fingers
    • Loss of pinch power
    • Wartenberg’s sign
  • Carpal Tunnel release- pts with both CTS and ulnar tunnel syndrome
19
Q

What is release in ulnar tunnel syndrome?

A
  • Local surgical decompression
    • release hypothenar muscle orgin
    • decompress ganglion cysts
    • resect hook of hamate
    • vascular tx of ulnar artery thrombosis
    • explore and release all 3 zones of Guyton’s canal
  • The incision for ulnar tunnel release has been described as in line with the radial aspect of the ring finger and lies between the palmar cutaneous branches of the median and ulnar nerves. The palmar cutaneous branch of the ulnar nerve is usually ulnar to the ring finger. In cadaveric dissections by Engber and Gmeiner (37), it was found in only five out of 21 specimens. The palmar portion of the incision can alternatively be made obliquely in a line that connects the pisiform and hamate (Fig. 4) or midway between the pisiform and hamate. It is usually extended proximally across the wrist crease in a Bruner-type fashion. The pisiform is found at the ulnar aspect of the wrist flexion crease. The hamate is 1.0 to 1.5 cm from the pisiform, in a line extending from the pisiform to the index metacarpal head). The proximal exposure allows accurate and safe identification of the ulnar neurovascular bundle, and the authors recommend that the dissection begin proximally. The ulnar nerve is found by spreading bluntly through the skin and subcutaneous tissues that are proximal to the wrist, identifying the FCU tendon and the volar carpal ligament. The FCU is retracted ulnarly, and the ulnar
    nerve is identified immediately radial to this tendon. The artery is radial and palmar to the nerve . The proximal edge of the volar carpal ligament is the entrance to zone 1 of the ulnar tunnel . Once the ligament is opened, the ulnar nerve is seen to pass deep to the palmaris brevis in zone 3. When the palmaris brevis is present, it must also be divided at the same time as the division of the volar carpal ligament.
  • http://www.msdlatinamerica.com/ebooks/HandSurgery/sid692657.html
20
Q

Describe the tendon transfers used in clawing?

A

Correct claw fingers

  • possible grafts include ERCL, ERCB, palaris longus
  • tendons must pass VOLAR to transverse the MC ligament in order to flex the proximal phaln=anx
  • Attach with either two or 4 tailed graft to A2 pulley of ring adn small fingers
  • restore power pinch
    • Smith transfer using ECRB/FDS ring finger
  • restore ulnar insertion of EDM to A1 pulley or radial collateral ligament to small finger

Nerves (17 decks)

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