Common Nerve Conditions of the Upper Extremity

Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

1. Nerve Injuries in Supracondylar Fracture of the Humerus (Children)

• Supracondylar fractures of the humerus in children are commonly associated with nerve injuries.

Extension Type (Most Common)

• Most common type of supracondylar fracture.

• Commonly associated with:

  • Anterior interosseous nerve (AIN) palsy

• It is essentially a high median nerve injury.

• Clinically presents as anterior interosseous nerve palsy.

Clinical Finding:

• Inability to make the “OK” sign.

  • Patient cannot form a circle with thumb and index finger.

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Flexion Type (Rare)

• Less common type.

• Associated with:

  • Ulnar nerve injury.

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2. Median Nerve Compression at the Elbow

Supracondylar Process of the Humerus

• A small bony projection called the supracondylar process (medial process of the humerus).

• Connected to a fibrous band (Struthers’ ligament).

• The ligament may compress the median nerve.

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Ligament of Struthers

• Can affect the median nerve.

• Median nerve may be compressed beneath this ligament.

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Arcade of Struthers

• A different structure.

• Affects the ulnar nerve.

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3. Radial Tunnel Syndrome / Posterior Interosseous Nerve Entrapment

• Caused by compression of the posterior interosseous nerve.

• Site of compression:

  • Proximal fibrous border of the superficial head of the supinator muscle.

• This structure is called the Arcade of Frohse.

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4. Radial Nerve Palsy

Causes

• Humerus fracture

• Trauma

• Surgery

Clinical Features

• Wrist drop

• Inability to extend the wrist

• Inability to extend the fingers

• Inability to perform the “hitchhike” sign (thumb extension)

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5. Posterior Interosseous Nerve (PIN) Palsy

• May occur independently of radial nerve palsy.

• The radial nerve divides into:

  • Posterior interosseous nerve

  • Superficial radial nerve

If Posterior Interosseous Nerve Alone is Affected:

• Inability to extend the fingers

• Inability to perform hitchhike sign

• Wrist extension is preserved

Difference from Radial Nerve Palsy:

• Radial nerve palsy:

  • Wrist drop present

  • Loss of finger extension

• PIN palsy:

  • Wrist extension present

  • Loss of finger extension only

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6. Ulnar Nerve Palsy

Clinical Presentation

• Clawing of the hand

• Clawing of the fourth and fifth fingers

Commonly Seen In:

• Low ulnar nerve injury (below the elbow)

Mechanism

• Weakness of intrinsic hand muscles

• Flexor digitorum profundus to the ring and little fingers may still function

• Results in claw deformity of these digits

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7. Quadrangular Space Syndrome

• Involves compression within the quadrangular space.

• Structures passing through this space:

  • Axillary nerve

  • Posterior humeral circumflex artery

• Compression affects the axillary nerve.