Differential Diagnosis for a 56-year-old man with slurred speech and right-sided facial drooping

Single most likely diagnosis

• Ischemic Stroke: The sudden onset of slurred speech and unilateral facial drooping is highly suggestive of a stroke, particularly one involving the brainstem or the left hemisphere of the brain, which could affect the motor areas controlling the right side of the face and speech.

Other Likely diagnoses

• Hemorrhagic Stroke: Similar to ischemic stroke, a hemorrhagic stroke could present with sudden focal neurological deficits, including slurred speech and facial weakness.
• Transient Ischemic Attack (TIA): Often referred to as a "mini-stroke," a TIA has symptoms similar to those of a stroke but typically lasts less than 24 hours. However, TIAs are warning signs for future strokes and require immediate medical attention.

Do Not Miss diagnoses

• Brain Tumor: Although less common than stroke, a brain tumor could cause focal neurological deficits, including speech and facial weakness, especially if it is located in a critical area such as the brainstem or the left cerebral hemisphere.
• Meningitis or Encephalitis: Infections like meningitis or encephalitis can present with a wide range of neurological symptoms, including sudden onset of speech difficulties and facial weakness, and are medical emergencies.
• Subarachnoid Hemorrhage: This condition, often due to an aneurysm rupture, can present with sudden severe headache and may also include focal neurological deficits.

Rare diagnoses

• Multiple Sclerosis: Although multiple sclerosis (MS) can cause a wide range of neurological symptoms, it typically presents in a more relapsing-remitting pattern rather than with sudden, focal deficits like those described.
• Amyotrophic Lateral Sclerosis (ALS): ALS is a progressive neurological disease that affects nerve cells in the brain and spinal cord, leading to loss of muscle control. Early symptoms can sometimes mimic those of a stroke, but ALS progresses over time and affects both sides of the body.
• Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes (MELAS): This is a rare mitochondrial disorder that can cause stroke-like episodes, among other symptoms. It is more common in younger individuals but can present at any age.