What is the most likely underlying etiology of intracerebral hemorrhage (ICH) in an elderly patient with a history of short-term memory loss and chronic microhemorrhages on Magnetic Resonance Imaging (MRI)?

Cerebral Amyloid Angiopathy

The most likely underlying etiology of this patient's intracerebral hemorrhage is cerebral amyloid angiopathy (CAA). This diagnosis is strongly supported by the combination of lobar (occipital) hemorrhage location, elderly age, presence of multiple juxtacortical microhemorrhages on MRI, history of short-term memory loss, and absence of deep hemorrhage location typically associated with hypertensive arteriopathy 1.

Key Diagnostic Features Supporting CAA

Location and Imaging Characteristics

• Lobar hemorrhages in elderly nonhypertensive patients are characteristically due to CAA, whereas deep hemorrhages in hypertensive patients typically result from chronic hypertension 1.
• The occipital location is a superficial/lobar site, which is the hallmark distribution for CAA-related hemorrhages due to preferential involvement of cortical and leptomeningeal vessels 2.
• Multiple juxtacortical microhemorrhages on susceptibility-weighted MRI sequences are highly specific for CAA and represent chronic hemorrhagic lesions from amyloid deposition in vessel walls 1.

Patient Demographics and Clinical Context

• At 80 years old, this patient falls within the typical age range for CAA, which predominantly affects elderly individuals 2, 3.
• The two-year history of short-term memory loss suggests underlying cognitive impairment, which is commonly associated with CAA due to shared pathophysiology involving β-amyloid deposition 1.
• The mild-moderate cerebral atrophy on CT further supports chronic neurodegenerative processes often seen with CAA 2.

Why Other Etiologies Are Less Likely

Chronic Hypertension

• While the patient has hypertension (BP 146/82), hypertensive hemorrhages typically occur in deep structures (basal ganglia, thalamus, pons, cerebellum) from rupture of penetrating subcortical vessels, not in lobar locations 1, 4.
• The presence of multiple cortical microhemorrhages argues against isolated hypertensive arteriopathy 1.

Metastatic Brain Tumor

• No contrast enhancement or mass lesion was identified on MRI with and without contrast 1.
• Hemorrhagic metastases would typically show surrounding vasogenic edema or an identifiable mass, which were not described 1.

Cerebral Vein Thrombosis

• This would present with a different clinical picture and imaging pattern, typically showing venous infarction with hemorrhagic transformation rather than isolated lobar hemorrhage 1.
• The clinical presentation and imaging findings are inconsistent with venous thrombosis.

Vertebral Artery Dissection

• This would cause posterior circulation ischemia or subarachnoid hemorrhage, not isolated occipital parenchymal hemorrhage 1.
• No vascular abnormalities were noted on MRI.

Clinical Implications and Management Considerations

Risk of Recurrence

• CAA-associated hemorrhages have an increased risk of recurrence compared to other ICH etiologies, particularly in lobar locations 1, 2.
• The presence of multiple microhemorrhages significantly elevates the risk of future bleeding events 5.

Anticoagulation Contraindications

• Multiple microhemorrhages (≥4) are a strong contraindication to anticoagulation due to substantially increased bleeding risk 5.
• Decision analysis studies recommend against anticoagulation in patients with lobar ICH, even in the presence of atrial fibrillation 1.

Blood Pressure Management

• While aggressive blood pressure control is important acutely, the underlying CAA pathology requires different long-term considerations than hypertensive arteriopathy 1.

Prognosis

• Patients with CAA-associated hemorrhages have lower acute mortality than hypertensive hemorrhages but higher recurrence rates 2.
• Poor outcomes are associated with dementia, increasing age, hematoma volume, and intraventricular extension 2.