Differential Diagnosis for Loss of Thumb Extension
- Single most likely diagnosis
- Tendon rupture of the extensor pollicis longus (EPL): This is the most common cause of loss of thumb extension, often resulting from trauma or repetitive strain, leading to a rupture of the tendon responsible for thumb extension.
- Other Likely diagnoses
- Radial nerve palsy: The radial nerve controls the muscles responsible for wrist and finger extension, including thumb extension. Damage to this nerve can result in an inability to extend the thumb.
- Posterior interosseous nerve (PIN) palsy: A branch of the radial nerve, the PIN specifically controls the muscles that extend the fingers and thumb. Damage to this nerve can lead to loss of thumb extension.
- Tendonitis of the extensor pollicis longus or brevis: Inflammation of the tendons that control thumb extension can lead to pain and weakness, resulting in a loss of function.
- Do Not Miss diagnoses
- Cervical radiculopathy (C6 or C7): Nerve root compression in the cervical spine can affect the nerves that control thumb movement, leading to weakness or paralysis of thumb extension. Missing this diagnosis could lead to prolonged neurological deficit if not addressed promptly.
- Stroke or cerebral vasculature issues: Although less common, a stroke affecting the motor areas of the brain responsible for thumb movement could result in loss of thumb extension. Early recognition is crucial for timely intervention and prevention of further brain injury.
- Rare diagnoses
- Amyotrophic lateral sclerosis (ALS): A progressive neurological disease that affects nerve cells in the brain and spinal cord, leading to loss of muscle control. Early symptoms can include weakness in specific muscle groups, such as those controlling thumb extension.
- Muscular dystrophy: Certain types of muscular dystrophy can affect the muscles of the forearm and hand, leading to weakness and loss of function, including thumb extension.
- Tumors affecting the radial nerve or PIN: Although rare, tumors can compress or damage the nerves responsible for thumb extension, leading to loss of function.