Differential Diagnosis for the Patient's Symptoms

The patient presents with a complex set of neurological symptoms including tingling of the left side of the face, confusion, intermittent headache, expressive aphasia, double vision, dilation of the left pupil, abnormal extraocular movement of the left eye, and drooping of the left eyelid. Considering the patient's medical history and the findings on the CT scan of the head, the differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis

  • Cerebral Aneurysm: The patient's symptoms such as tingling of the face, confusion, headache, and specific ocular findings (dilation of the pupil, abnormal extraocular movement, drooping of the eyelid) along with the CT scan finding of the posterior communicating artery being well-defined and circumscribed with mild focal dilation, strongly suggest a cerebral aneurysm, particularly one affecting the posterior communicating artery or the oculomotor nerve (cranial nerve III). The patient's history of hypertension and Marfan syndrome also increases the risk for cerebral aneurysms.

• Other Likely Diagnoses

  • Migraine: Given the patient's history of intermittent headaches and the presence of neurological symptoms such as tingling and expressive aphasia, migraine with aura could be considered. However, the specific ocular findings and the CT scan results make this less likely.
  • TIA (Transient Ischemic Attack): The patient's symptoms could also suggest a TIA, especially given the history of hypertension. However, the presence of specific ocular findings and the CT scan results pointing towards an aneurysm make TIA less likely.
  • Complex Partial Seizure: Although less likely, the patient's confusion and expressive aphasia could be indicative of a complex partial seizure. However, the specific pattern of neurological deficits and the CT scan findings do not strongly support this diagnosis.

• Do Not Miss Diagnoses

  • Subarachnoid Hemorrhage: Although the CT scan does not explicitly mention blood in the subarachnoid space, the presence of a cerebral aneurysm increases the risk of rupture, which could lead to a subarachnoid hemorrhage. This is a potentially life-threatening condition that must be considered.
  • Stroke: Given the patient's symptoms and history of hypertension, a stroke (either ischemic or hemorrhagic) must be considered, especially if the aneurysm has ruptured or if there are other vascular issues.

• Rare Diagnoses

  • Arteriovenous Malformation (AVM): While less likely, an AVM could present with similar symptoms, especially if it involves the posterior communicating artery or surrounding structures. The CT scan findings do not specifically suggest an AVM, but it remains a rare possibility.
  • Vasculitis: Inflammatory diseases affecting the blood vessels, such as vasculitis, could potentially cause the patient's symptoms. However, this would be a rare diagnosis and would require further investigation to confirm.