Differential Diagnosis for Unilateral Headache and Sensitivity to Light

• Single Most Likely Diagnosis
  • Migraine: This is the most common cause of unilateral headache and photophobia. Migraines are often characterized by intense, throbbing pain, usually on one side of the head, and are frequently accompanied by sensitivity to light, sound, and sometimes nausea and vomiting.
• Other Likely Diagnoses
  • Cluster Headache: Known for severe, unilateral orbital or periorbital pain, cluster headaches can also present with photophobia and are more common in men. They occur in cyclical patterns or clusters.
  • Tension-Type Headache: Although typically bilateral, some cases can present unilaterally and with mild sensitivity to light. They are usually described as a band or a squeezing sensation around the forehead.
  • Sinusitis: Inflammation of the sinuses can cause unilateral headache, especially if the infection is localized to one side. It may be accompanied by facial pain, nasal congestion, and sensitivity to light.
• Do Not Miss Diagnoses
  • Subarachnoid Hemorrhage: A life-threatening condition caused by bleeding into the space surrounding the brain. It often presents with a sudden, severe headache (often described as "the worst headache of my life") and can be accompanied by photophobia and vomiting.
  • Temporal Arteritis: An inflammatory condition affecting the blood vessels, particularly those in the head. It can cause unilateral headache, jaw claudication, and visual disturbances, including sensitivity to light. It's a medical emergency due to the risk of blindness.
  • Acute Angle-Closure Glaucoma: A condition where the pressure in the eye increases rapidly, causing severe eye pain, headache, blurred vision, and sensitivity to light. It's an ophthalmologic emergency requiring immediate treatment.
• Rare Diagnoses
  • Trigeminal Neuralgia: Characterized by sudden, severe, shock-like pain around the eyes, lips, or nose mainly on one side of the face, which can sometimes be accompanied by sensitivity to light.
  • Occipital Neuralgia: Involves inflammation of the occipital nerves and can cause severe, unilateral headache and sensitivity to light, often accompanied by neck pain.
  • Hemicrania Continua: A rare headache disorder characterized by a continuous, unilateral headache with periods of exacerbation, often accompanied by autonomic symptoms like tearing and redness of the eye on the same side as the headache.