Cubital Tunnel Syndrome: Differential Diagnosis and Conditions to Rule Out

Cubital tunnel syndrome (ulnar nerve entrapment at the elbow) must be distinguished from other conditions causing similar ulnar-sided arm/hand symptoms. Key differentials include:

1. Cervical Spine Pathology

• Cervical radiculopathy (C8–T1) mimics ulnar nerve sensory/motor deficits.
• Degenerative disc disease, foraminal stenosis, spondylosis.

2. Thoracic Outlet Syndrome (TOS)

• Neurogenic TOS compresses the lower trunk (C8–T1) of the brachial plexus.
• Symptoms worsen with arm elevation; Adson's, Roos, and Wright tests help differentiate.

3. Peripheral Neuropathy

• Diabetic neuropathy, alcohol-related, chemotherapy-induced.
• Typically symmetric, stocking-glove distribution; nerve conduction studies (NCS) show generalized slowing.

4. Brachial Plexus Injury

• Trauma, radiation plexopathy, Parsonage-Turner syndrome.
• May affect multiple nerve distributions; imaging (MRI) and NCS localize lesion.

5. Proximal Ulnar Nerve Entrapment (Other Sites)

• Arcade of Struthers (distal arm), Guys's canal (wrist), cubital tunnel (elbow).
• Tinel's sign at wrist suggests Guyon's canal; at elbow suggests cubital tunnel.

6. Vascular Disorders

• Peripheral artery disease, subclavian steal, thrombosis, aneurysm.
• Associated with pulse changes, coolness, discoloration; vascular studies indicated.

7. Musculoskeletal/Soft Tissue

• Medial epicondylitis, triceps tendinopathy, synovial cysts, lipomas.
• Pain localized to elbow; nerve studies normal.

8. Inflammatory/Infectious

• Septic arthritis, rheumatoid arthritis, gout, Lyme disease.
• Systemic signs, joint swelling, elevated inflammatory markers.

Diagnostic Approach

• Detailed history and neurological exam (sensory, motor, reflexes).
• Electrodiagnostic studies (NCS/EMG) – gold standard for localization.
• Imaging: MRI (cervical spine, brachial plexus, elbow), ultrasound (nerve cross-sectional area).
• Laboratory: Glucose, HbA1c, B12, thyroid, inflammatory markers if indicated.

Accurate localization ensures appropriate treatment (conservative vs. surgical).