Differential Diagnosis for 18 weeks pregnant, 31 year old female with history of diabetes, severe headache, and partial response to decadron and magnesium

• Single most likely diagnosis:
  • Preeclampsia: This condition is characterized by high blood pressure and often protein in the urine, occurring after the 20th week of pregnancy. The patient's severe headache and partial response to decadron (a corticosteroid) and magnesium (used for seizure prophylaxis in preeclampsia) suggest this diagnosis, although the gestational age is slightly earlier than typical.
• Other Likely diagnoses:
  • Migraine: Given the patient's severe headache, migraine is a possibility, especially if she has a history of migraines. The partial response to decadron could support this, as corticosteroids are sometimes used in migraine treatment.
  • Gestational hypertension: Similar to preeclampsia but without the proteinuria, this could be a consideration given the patient's symptoms and response to treatment.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Subarachnoid hemorrhage or other cerebral vascular accidents: Although less likely, these conditions are medical emergencies that could present with a severe headache and would require immediate intervention.
  • Posterior reversible encephalopathy syndrome (PRES): This is a condition associated with preeclampsia and can cause severe headaches, seizures, and visual disturbances. It's crucial to consider due to its potential for serious complications.
  • Venous sinus thrombosis: This is a rare condition but can occur in pregnancy, especially with a history of diabetes, and presents with headache and possibly other neurological symptoms.
• Rare diagnoses:
  • Reversible cerebral vasoconstriction syndrome (RCVS): A rare condition that can mimic other diagnoses like migraine or preeclampsia but involves vasoconstriction of cerebral arteries.
  • Idiopathic intracranial hypertension (IIH): Although more common in obese females of childbearing age, the presentation of severe headache could suggest IIH, especially if there are symptoms like visual disturbances.