Differential Diagnosis for Recurrent Thunderclap Headaches in a 56-year-old Male with Previous Left MCA Infarct

• Single Most Likely Diagnosis
  • Reversible Cerebral Vasoconstriction Syndrome (RCVS): This condition is characterized by recurrent thunderclap headaches and is often associated with cerebral vasoconstriction. Given the patient's history of a previous left MCA infarct, RCVS is a plausible diagnosis as it can sometimes be triggered by or occur in conjunction with other cerebrovascular events.
• Other Likely Diagnoses
  • Migraine: Although migraines can cause severe headaches, the "thunderclap" nature of the headaches might be less typical. However, given the patient's history, migraines could be considered, especially if there are other migraine-like features.
  • Arteritis (e.g., Giant Cell Arteritis): This condition can cause severe headaches and is more common in older adults. While it might not be the first consideration for thunderclap headaches, the patient's age and history of cerebrovascular disease make it a plausible differential.
• Do Not Miss Diagnoses
  • Subarachnoid Hemorrhage (SAH): This is a medical emergency that can present with a sudden, severe headache (often described as "the worst headache of my life"). Given the potential for catastrophic outcomes if missed, SAH must be considered, even if the patient has had a previous stroke.
  • Cerebral Vasculitis: This condition involves inflammation of the blood vessels in the brain and can cause a variety of symptoms, including severe headaches. It's crucial to consider due to its potential for serious complications if not treated.
  • Dissection of the Carotid or Vertebral Artery: Arterial dissections can lead to stroke and may present with severe headache. Given the patient's history of a previous MCA infarct, this diagnosis is particularly relevant.
• Rare Diagnoses
  • Primary Angiitis of the Central Nervous System (PACNS): A rare condition that involves inflammation of the blood vessels in the brain and spinal cord. It can cause a range of symptoms, including headaches, and is important to consider due to its potential severity.
  • Cerebral Venous Thrombosis: This condition involves a blood clot in the veins of the brain and can cause severe headaches among other symptoms. It's less common but should be considered, especially in patients with risk factors for thrombosis.
  • Pituitary Apoplexy: A rare condition that occurs when there is sudden hemorrhage or infarction of the pituitary gland, often presenting with a severe headache. It's an important differential due to its acute onset and potential for serious complications.