Differential Diagnosis for a 10-year-old with a Severe Headache

Single Most Likely Diagnosis

• Tension Headache: This is the most common type of headache in children and is often described as a band or a squeezing sensation around the forehead, usually mild to moderate but can be severe. It's typically bilateral and can be exacerbated by stress, fatigue, or poor posture.

Other Likely Diagnoses

• Migraine: A common cause of severe headaches in children, often unilateral, throbbing, and accompanied by nausea, vomiting, photophobia, or phonophobia. Family history is a significant risk factor.
• Viral Infections: Such as influenza or other viral upper respiratory infections, which can cause headaches due to fever, inflammation, or increased intracranial pressure.
• Sinusitis: Inflammation of the sinuses can cause headaches, typically facial or frontal, accompanied by nasal congestion, fever, and cough.

Do Not Miss Diagnoses

• Meningitis: An infection of the meninges, which can present with severe headache, fever, stiff neck, and altered mental status. It's a medical emergency requiring prompt diagnosis and treatment.
• Encephalitis: Inflammation of the brain, usually due to viral infections, which can cause severe headache, fever, confusion, and seizures.
• Subarachnoid Hemorrhage: Bleeding into the space surrounding the brain, which can cause a sudden, severe headache (often described as "the worst headache of my life"), and may be accompanied by vomiting, seizures, or loss of consciousness.
• Brain Tumor: Although rare, can cause increased intracranial pressure leading to severe headaches, often worse in the morning and improving throughout the day, accompanied by nausea, vomiting, and visual disturbances.

Rare Diagnoses

• Pseudotumor Cerebri (Idiopathic Intracranial Hypertension): Characterized by increased intracranial pressure without a detectable cause, leading to severe headaches, visual disturbances, and sometimes papilledema.
• Arteriovenous Malformation (AVM): A congenital condition where there's an abnormal connection between arteries and veins in the brain, which can cause severe headaches and may lead to bleeding.
• Temporal Arteritis: Inflammation of the blood vessels in the temples, more common in older adults but can occur in children, causing severe headaches, jaw claudication, and visual disturbances.

Each of these diagnoses requires careful consideration of the patient's history, physical examination, and potentially, diagnostic imaging or laboratory tests to determine the underlying cause of the severe headache.