Differential Diagnosis for Unable to Bend Thumb and Numbness

• Single Most Likely Diagnosis
  • Carpal Tunnel Syndrome: This condition is characterized by compression of the median nerve as it passes through the wrist, leading to numbness, tingling, and weakness in the hand, particularly affecting the ability to bend the thumb.
• Other Likely Diagnoses
  • Radial Nerve Palsy: Although more commonly associated with wrist drop, certain types of radial nerve injury can affect thumb movement and sensation.
  • Ulnar Nerve Entrapment: This can cause numbness and weakness, particularly in the little and ring fingers, but in some cases, it might affect thumb movement indirectly due to overall hand weakness.
  • Cervical Radiculopathy: Nerve root compression in the cervical spine can cause numbness and weakness in the arm and hand, including the thumb, depending on which nerve root is affected.
• Do Not Miss Diagnoses
  • Acute Compartment Syndrome: A medical emergency that can cause numbness, weakness, and loss of function in the hand due to increased pressure within the muscle compartments.
  • Brachial Plexus Injury: A serious condition that can result from trauma, causing numbness, weakness, and paralysis of the arm, including the thumb.
• Rare Diagnoses
  • Tumors (e.g., schwannoma, neurofibroma): Rarely, tumors can compress nerves, leading to symptoms like numbness and weakness.
  • Inflammatory Neuropathies (e.g., Guillain-Barré Syndrome): Although rare, these conditions can cause rapid onset of numbness, weakness, and sometimes paralysis.
  • Vascular Conditions (e.g., thrombosis, embolism): Rare vascular events can lead to acute loss of function and sensation in the hand.