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Cubital-Tunnel-Syndrome-Ulnar-Neuropathy

Cubital Tunnel Syndrome (Ulnar Neuropathy): Pathogenesis and clinical findings Osteoarthritis Rheumatoid arthritis Diabetes mellitus (see Calgary Guide slide on Diabetic Neuropathy) Degenerative bone & joint changes Autoimmune damage to joints Abnormal bone structure/lesions Idiopathic Hyperglycemia causes nerve damage (complex mechanisms) Elbow trauma Repetitive elbow flexion Authors: Chris Oleynick Alexandros Mouratidis Yan Yu* Reviewers: Annalise Abbott Sean Crooks Davis Maclean Hannah Koury Jeremy LaMothe* Ian Auld* * MD at time of publication Inflammation or edema in cubital tunnel (space between medial epicondyle of humerus and olecranon of ulna) where ulnar nerve is found ↓ size of the cubital tunnelà↑ pressure on internal contents (e.g. ulnar nerve) Axonal conduction is interrupted Myelin sheath is damaged ↓ blood supply to nerve Weakness of adductor pollicus longus (works to adduct thumb) ↑ compensatory activity of flexor pollicis longus with pinching ↓ activity of hypothenar muscles (which move the 5th digit) ↓ activity of 5th digit palmar interosseus muscles (which adduct the 5th digit) Cubital Tunnel syndrome: compression neuropathy Paresthesia Abnormal sensations of skin (“pins & needles”, tingling, burning, and/or numbness) in ulnar nerve sensory distribution ulnar nerve ↓ activity of muscles innervated by ulnar nerve (medial forearm flexors, hypothenar muscles, interossei muscles, adductor pollicis longus) + Tinel sign over cubital tunnel (tapping at medial elbow causes discomfort and/or paresthesia) Weak pinch & ↓ grip strength + Froment’s sign (thumb hyperflexion compensates for weak pinch) Hypothenar atrophy + Wartenburg’s sign (involuntary, excess abduction of 5th digit) of the Altered sensation in areas innervated by ulnar nerve (medial forearm and wrist, 5th digit, and medial half of 4th digit) + elbow flexion test (flexing elbow & extending wrist further ↓ volume of the cubital tunnelà paresthesia in ulnar nerve sensory distribution Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications First published January 12, 2017, re-published February 28, 2021 on www.thecalgaryguide.com