Differential Diagnosis for Left Sided Weakness
Single Most Likely Diagnosis
- Stroke: The most common cause of sudden onset left sided weakness is a stroke, particularly an ischemic stroke affecting the right hemisphere of the brain, which controls the left side of the body. This is due to the high prevalence of stroke in the population and its direct impact on motor function.
Other Likely Diagnoses
- Multiple Sclerosis: An autoimmune disease that affects the brain and spinal cord, leading to a wide range of neurological symptoms, including weakness. While less common than stroke, it's a significant consideration, especially in younger patients.
- Spinal Cord Injury or Lesion: Any injury or lesion affecting the right side of the spinal cord can lead to left sided weakness. This could be due to trauma, infection, or other causes.
- Peripheral Neuropathy: Conditions affecting the peripheral nerves, such as mononeuritis multiplex or a radiculopathy, can cause weakness, although this is typically more localized than the diffuse weakness seen with central causes.
Do Not Miss Diagnoses
- Brain Tumor: Although less common, a tumor in the right hemisphere of the brain can cause progressive left sided weakness. Missing this diagnosis could lead to delayed treatment and poor outcomes.
- Subdural Hematoma: Especially in the elderly or those on anticoagulation, a subdural hematoma can present with gradual onset of weakness and is critical to identify due to the need for urgent surgical intervention.
- Cervical Spine Injury: Acute injuries to the cervical spine can result in spinal cord compression, leading to weakness. This is particularly critical to identify in the context of trauma.
Rare Diagnoses
- Mitochondrial Myopathies: A group of rare genetic disorders that affect the mitochondria, leading to muscle weakness among other symptoms.
- Inflammatory Myopathies: Conditions like polymyositis or dermatomyositis can cause progressive muscle weakness, although they typically present with bilateral symptoms.
- Neurodegenerative Diseases: Such as amyotrophic lateral sclerosis (ALS), which can present with focal weakness, although this is less common and usually progresses to involve other areas.