Differential Diagnosis for Headache Better When Lying Flat

• Single Most Likely Diagnosis
  • Migraine: Some individuals with migraine may experience relief when lying down in a quiet, dark room, which can help alleviate the headache. However, this is not a universal characteristic of migraines, as many people find that their migraine symptoms are not significantly affected by posture.
• Other Likely Diagnoses
  • Tension Headache: Lying down can sometimes relieve tension headaches by reducing muscle tension and promoting relaxation.
  • Sinus Headache: Although sinus headaches are typically worsened by lying down due to increased sinus pressure, some individuals might experience relief if the position helps to drain the sinuses or reduce facial pressure.
• Do Not Miss Diagnoses
  • Subarachnoid Hemorrhage (SAH) or other Intracranial Hemorrhages: While these conditions are typically associated with worsening symptoms when lying down due to increased intracranial pressure, it's crucial to consider them in the differential diagnosis due to their severe and potentially life-threatening nature. However, improvement with lying flat would be atypical.
  • Meningitis: Similar to SAH, meningitis is a serious condition that usually presents with worsening symptoms when lying down, but it must be considered due to its potential severity and the importance of early treatment.
• Rare Diagnoses
  • Low-Pressure Headache (Spontaneous Intracranial Hypotension): This condition is characterized by a headache that worsens with standing and improves or resolves with lying down. It's caused by a leak of cerebrospinal fluid, often spontaneous but sometimes due to trauma or procedures.
  • Chiari Malformation: Some patients with Chiari malformation may experience headaches that improve with lying down, although this is not a consistent feature and symptoms can vary widely among affected individuals.

It's essential to conduct a thorough medical history and physical examination, and potentially further diagnostic tests, to accurately diagnose the cause of a headache that improves when lying flat.