Ulnar nerve compression/entrapment (UNE) is the second most common neuropathy in upper extremity . This condition can cause numbness or tingling of the little finger and half of the ring finger, which is the course of ulnar nerve . Symptoms such as weakness, numbness and tingling occur intermittently as it is a neuropraxia . Ulnar nerve entrapment can occur at some sites below. The most common site where it gets compressed is the medial elbow also called cubital tunnel syndrome. Cubital is formed by Osborne’s ligament that attaches to medial epicondyle, olecranon process and flexor carpi ulnaris (FCU) as a roof and medial collateral ligament (ulna collateral ligament) .
Sites where ulnar nerve can get compressed 
· Arcade of struthers (2)
· Aponeurotic band from medial head of triceps
· At cubital tunnel between Osbourn’s ligament and medial collateral ligament (3)
· Between two heads of flexor carpi ulnaris (most common, HUA in the fig.1)
· between flexor carpi ulnaris and flexor digitorum profundus (FDP) (4)
· Guyon’s canal
The second prevalent area is at wrist called Guyon’s canal syndrome . Ulnar nerve compression at Guyon’s canal is seen in cyclists due to excessive pressure on the canal. Splinting and modification of activity are the main conservative treatments for Guyon’s canal syndrome .
Structure of Guyon’s canal 
|Boundaries of Guyon’s canal||Structure|
|Superior (Roof)||Palmer carpal ligament, palmaris brevis and hypothenar connective tissue|
|Medial||Pisiform, flexor carpi ulnaris tendon|
|Lateral||Hook of hamate, transversa carpal ligament|
|Inferior (floor)||Transversa carpal ligament, flexor digitorum profundus tendon and opponens digiti minimi tendon|
Mechanism of the pathology 
Static: direct compression such as leaning on the elbow, hitting the medial elbow, pressure on the wrist while riding a bicycle
Dynamic: Elbow flexion overstretches ulnar nerve due to subluxation  and flexion of the elbow to 135° causes compression at Osborne’s ligament and Medial collateral ligament (MCL) .
*Elbow flexion can decrease the space in the cubital tunnel and increase intracanal pressure .
*Ulnar nerve instability could be a cause of ulnar nerve entrapment. However, this can be seen in asymptomatic population .
This is like a no correlation about subacromial space between symptomatic and asymptomatic shoulder pain patients! Ref.
Aetiology [1,2, 6]
· Male > Female
· Valgus force at the elbow
· Excessive pressure on the medial elbow or hypothenar eminence
· Compression by flexor carpi ulnaris due to excessive griping and twisting.
· Prolonged sitting or ride of the bicycle
· Throwing athletes
· Traction injury
· Ganglion cyst
· Tardy ulnar palsy (ulnar nerve compression due to previous trauma, osteoarthritis, fracture or dislocation) .
· Hypermobile ulnar nerve .
Signs and symptoms [1,2,3]
Ulnar nerve has motor and sensory functions. Thus, compression of the ulnar nerve may manifest the sensory and motor deficit or one of them . However, it may not show this symptom in the early stage .
· Medial elbow pain
· Numbness and tingling in the little finger and ulna side of the forearm
· Weakness in the hand and fingers as ulnar nerve innervates the adductor pollicis, dorsal and palmer interossei, and 3rd and 4th lumbricals, opponens digiti minimi, flexor digiti minimi and abductor digiti minimi (hypothenar muscles) .
· Pain becomes worse in the night
· Claw hand in severe case .
Manual muscle testing of wrist flexion and ulna deviation as FCU is the common muscle to get affected .
· Resisted the little finger flexion as FDP can be affected .
· Resisted the little finger abduction to test abductor digiti minimi .
· Test adductor pollicis muscle weakness by making a circle and hold something between thumb and index fingers (Froment’s sign) .
· Tinels sign (sensitivity 70%, specificity 98%, PPV=94%, NPV=87%) .
· 30 secs of ulnar nerve direct compression test (sensitivity 55%, specificity 98%, PPV=92%, NPV=81%) .
· 60 secs of ulnar nerve direct compression test (sensitivity 89%, specificity 98%, PPV=95%, NPV=95%) .
· 30 secs of ulnar nerve direct compression test with flexion test (sensitivity 91%, specificity 97%, PPV=93%, NPV=96%) .
· 60 secs of ulnar nerve direct compression test with flexion test (sensitivity 98%, specificity 95%, PPV=91%, NPV=99%) .
· Wrist scratch collapse test (sensitivity 64%, specificity 99%, PPV=99%, NPV=73%) 
· Elbow scratch collapse test (sensitivity 69%, specificity 99%, PPV=99%, NPV=86%) 
· Full elbow flexion or ulnar nerve neural tension test (ULNT3).
*MRI, Ultrasound, EMG can be used to identify ulnar nerve compression .
Differential diagnosis 
· Medial epycondylalgia (golfer’s elbow)
· Cervical nerve root C8 or/and T1 impingement
· Thoracic outlet syndrome
· Brachial plexopathy
· Pancoast tumor
·Horner’s syndrome due to C8-T1 ventral root avulsion (Ptosis: dropped eyelid, myosis: small pupil and annydrosis: inability to sweat)
· DASH (disability of arm, shoulder and hands)
· Upper extremity functional index
Conservative treatment has approximately 50% of the successful rate for this condition [5,7]. If pain persists, surgical intervention may be required.
Use pads, splints or braces [5,7].
Advice (avoid provocative movement positions such as direct compression on the elbow and full flexion of the elbow when sleeping) .
Night splint vs nerve glide for 3 months vs no night splint or nerve glide exercise on moderate ulnar nerve entrapment. All groups have received information about the anatomy, pathology and advice for management of the condition. No difference between groups in function, pain and strength at 6 months follow-up .
Dry needling with neurodynamic sliders
This case study investigated the efficacy of Dry needling (DN) on 3 people with cubital tunnel syndrome. They received DN sessions twice a week for two weeks and were advised to perform ulnar nerve neurodynamic sliders of 3 sets of 15 repetitions every day. DN technics were categorised into 9 and chosen depending on the locations (FCU or between medial epicondyle and olecranon) and patient conditions. All three reported that pain level (Numeric Pain Scale) and function (Patient specific functional scale) improved in 2 weeks as well as no relapse seen at 4-6months follow up. Although good outcomes were seen in this study, it remains unclear whether DN helped or Neurodynamic mobilisation did .
Nerve gliding exercise showed some reduction of pain level at 3weeks -1months follow up . However, studied were investigated for carpal tunnel syndrome.
Education and advice to modify the activities that aggravate pain or symptoms can be used as an intervention for UNE. Comparing education, splinting and nerve glide all showed improvements in Canadian Occupational Performance Measure, VAS and strength at 6 months follow up with no difference between groups .
· Steroid injection or dextrose can be used .
· Laser, shockwave therapy may be effective although there is no evidence suggesting these interventions to UNE, as it is shown the effectiveness on carpal tunnel syndrome .
Improvement was reported in pain level and grip strength at 3 weeks and 12 weeks .
· Surgery .
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