Differential Diagnosis for the Presented Case

The patient's history and symptoms suggest a traumatic brain injury, given the fall onto the head. However, the absence of immediate severe symptoms and the delayed onset of significant weakness are crucial for narrowing down the differential diagnoses.

• Single Most Likely Diagnosis

  • B. Chronic Subdural Hematoma: This is the most likely diagnosis given the patient's age, the mechanism of injury (fall onto the head), and the delayed presentation with progressive weakness without immediate severe symptoms after the fall. Chronic subdural hematomas are more common in the elderly and can present with subtle or delayed symptoms due to the gradual expansion of the hematoma.

• Other Likely Diagnoses

  • D. Subacute Subdural Hematoma: This could be considered if the symptoms presented slightly earlier than expected for a chronic subdural hematoma but not immediately after the fall. The subacute phase typically refers to a period between acute and chronic, where symptoms may evolve over days to weeks.
  • A. Acute Subdural Hematoma: Although less likely given the delayed presentation, an acute subdural hematoma could be considered if there were immediate symptoms after the fall that were initially mild or overlooked, with progression of symptoms over the two weeks.

• Do Not Miss Diagnoses

  • C. Extradural (Epidural) Hemorrhage: Although extradural hemorrhages typically present acutely with a loss of consciousness and severe headache due to the rapid increase in intracranial pressure, a small or slowly expanding hemorrhage could potentially present in a more delayed fashion, especially in the context of anticoagulation or other complicating factors. Missing this diagnosis could be catastrophic due to the potential for rapid deterioration.
  • Other Traumatic Injuries: Including spinal injuries or other systemic injuries that could contribute to the patient's weakness and inability to walk, which might not be immediately apparent on the CT scan of the brain.

• Rare Diagnoses

  • Spontaneous Intracranial Hemorrhage: Although the patient had a fall, spontaneous hemorrhages can occur, especially in the context of hypertension, vascular malformations, or tumors. These would be less likely given the history of trauma but should be considered if other explanations are ruled out.
  • Infectious or Inflammatory Causes: Such as brain abscesses or encephalitis, which could present with focal neurological deficits and might show hypodense lesions on CT, although these would be uncommon without other systemic signs of infection or inflammation.