Ischemic Stroke or Transient Ischemic Attack (TIA): Given the patient's history of hypertension, symptoms such as expressive aphasia, confusion, intermittent headache, and the presence of neurological deficits like drooping of the left eyelid, dilation of the left pupil, and abnormal extraocular movement of the left eye, a stroke or TIA is highly plausible. The patient's age and vascular risk factors further support this diagnosis.

Aneurysm or Arteriovenous Malformation (AVM): The patient's symptoms, including the sudden onset of headache, confusion, and specific neurological deficits, could be indicative of an aneurysm or AVM, especially given the history of Marfan syndrome, which increases the risk of vascular abnormalities.
Multiple Sclerosis: Although less likely given the patient's age and the specific constellation of symptoms, multiple sclerosis could present with a wide range of neurological symptoms, including vision problems, confusion, and specific deficits like aphasia.
Cocaine-induced Vasculitis or Vasoconstriction: The patient's use of cocaine could lead to vasculitis or vasoconstriction, potentially causing stroke-like symptoms or other neurological deficits.

Subarachnoid Hemorrhage: This is a medical emergency that can present with sudden, severe headache, confusion, and neurological deficits. Given the patient's symptoms and potential for vascular abnormalities due to Marfan syndrome, missing this diagnosis could be catastrophic.
Brain Tumor: Although less likely, a brain tumor could cause a variety of neurological symptoms, including those presented by the patient. The gradual onset of some symptoms could suggest a mass effect from a tumor.
Infectious or Inflammatory Causes (e.g., Encephalitis, Meningitis): These conditions can present with confusion, headache, and neurological deficits. Given the potential severity and need for prompt treatment, they should not be missed.

Migraine Variant: Some migraine variants can present with neurological symptoms similar to those described, including aphasia and visual disturbances. However, the presence of other symptoms like pupil dilation and specific extraocular movement abnormalities makes this less likely.
Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes (MELAS): This rare condition can cause stroke-like episodes, encephalomyopathy, and other symptoms. It is more common in younger individuals but could be considered in the differential diagnosis of stroke-like symptoms in the appropriate clinical context.
Syphilis (Neurosyphilis): This condition can cause a wide range of neurological symptoms, including those described. However, it would be less likely without other supporting evidence or risk factors.