II. Pathophysiology

  1. Radial Nerve tracks follows the spiral groove down the medial Humerus

III. Causes

  1. Mid-shaft Humerus Fracture
    1. Direct injury to the Radial Nerve as it lies in spiral groove
    2. Does not typically affect elbow extension (triceps)
  2. Axilla compression (Saturday Night Palsy, Crutch Palsy)
    1. Falling asleep with arm over the back of a chair or bench, often inebriated (Saturday Night Palsy)
    2. Results in loss of elbow extension (triceps) and a Wrist Drop
  3. Honeymooner's Wrist Drop
    1. Shoulder and upper arm compressed under the arm/body of their partner resulting in local compression

IV. Signs

  1. Weak elbow extension
    1. Occurs if Radial Nerve injury at the axilla
  2. Wrist Drop
    1. Weak wrist and digit extensors
  3. Sensory loss
    1. Dorsal hand numbness (including lateral 3.5 digits)

V. Management

  1. Avoid repeat compression
  2. Physical Therapy
    1. Highly effective after 6 months
  3. Cock-Up Wrist Splint
    1. Maintains normal hand function when Wrist Drop present
  4. Surgery indications
    1. Humerus Fracture with Radial Nerve compromise

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