Differential Diagnosis for Right Arm Weakness
Single most likely diagnosis
- Radial neuropathy or radial nerve compression: This condition is likely due to the patient's recent activity of working on a lawn mower, which may have caused compression or injury to the radial nerve. The weakness in rotation and biceps, without pain, supports this diagnosis.
Other Likely diagnoses
- Brachial plexus injury: The brachial plexus is a network of nerves that originates in the spinal cord and controls muscle movements in the arm. Injury to the brachial plexus can cause weakness, numbness, or paralysis in the arm. The patient's symptoms of weakness in the right arm, particularly with rotation and biceps, could be indicative of a brachial plexus injury.
- Cervical radiculopathy: This condition refers to damage or irritation of the nerve roots in the cervical spine, which can cause weakness, numbness, or pain in the arm. The patient's symptoms of weakness in the right arm, without pain, could be related to cervical radiculopathy, particularly if the patient has a history of neck problems.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Stroke or transient ischemic attack (TIA): Although the patient reports no pain, it is essential to consider the possibility of a stroke or TIA, as these conditions can present with sudden weakness or numbness in one arm. Prompt diagnosis and treatment are critical to prevent long-term damage or death.
- Thoracic outlet syndrome: This condition involves compression of the nerves or blood vessels that pass through the thoracic outlet, which can cause weakness, numbness, or pain in the arm. While less likely, thoracic outlet syndrome is a potential diagnosis that should not be missed, as it can lead to serious complications if left untreated.
Rare diagnoses
- Amyotrophic lateral sclerosis (ALS): ALS is a progressive neurological disease that affects nerve cells in the brain and spinal cord, leading to muscle weakness and atrophy. While rare, ALS is a possible diagnosis to consider, particularly if the patient's symptoms worsen over time.
- Lead poisoning: Lead poisoning can cause a range of symptoms, including weakness, numbness, or paralysis in the arms. Although rare, lead poisoning is a potential diagnosis to consider, particularly if the patient has been exposed to lead through their work or environment.