Differential Diagnosis for Pulsing Sharp Headache Pain

The patient is being treated with cefdinir and azithromycin for bacterial pneumonia and now presents with pulsing sharp headache pain that occurs 30-60 seconds apart, with a persistent fever. Here is a differential diagnosis organized into categories:

• Single Most Likely Diagnosis
  • Viral or bacterial meningitis: The headache pattern, combined with fever and the context of a current infection (pneumonia), suggests central nervous system involvement. Meningitis could be a complication of the pneumonia or a separate infection.
• Other Likely Diagnoses
  • Sinusitis: Given the symptoms of headache and fever, sinusitis could be a consideration, especially if the pneumonia has led to a secondary infection in the sinuses.
  • Intracranial abscess: As a complication of pneumonia, especially if caused by certain bacteria like Streptococcus pneumoniae, an intracranial abscess could present with headache and fever.
  • Encephalitis: Inflammation of the brain tissue, which could be due to viral or bacterial causes, and is consistent with the symptoms of headache and fever.
• Do Not Miss Diagnoses
  • Subarachnoid hemorrhage: Although less likely given the context, a sudden onset of severe headache (often described as "the worst headache" of one's life) could indicate a subarachnoid hemorrhage, which is a medical emergency.
  • Brain tumor: Less likely but critical to consider, as some brain tumors can present with intermittent headache patterns and fever if there is associated infection or necrosis.
  • Cerebral venous sinus thrombosis: A rare but potentially life-threatening condition that could occur in the context of infection or dehydration, presenting with headache and possibly fever.
• Rare Diagnoses
  • Temporal arteritis: Although more common in older adults, temporal arteritis could present with headache and fever, and is a diagnosis that should be considered to avoid missing this condition.
  • Idiopathic thunderclap headache: A rare condition characterized by a very severe headache with a sudden onset, which could be considered if other diagnoses are ruled out.

Each of these diagnoses requires careful consideration of the patient's symptoms, medical history, and current treatment, as well as further diagnostic testing to determine the underlying cause of the pulsing sharp headache pain.