What is the most likely cause of a left thalamic intracerebral hemorrhage in a 31‑year‑old with normal blood pressure, acute headache, vomiting, and right‑sided homonymous hemianopia?

Likely Cause of Left Thalamic Hemorrhage in a Young Normotensive Patient

In a 31-year-old with normal blood pressure and left thalamic hemorrhage presenting with headache, vomiting, and right homonymous hemianopia, the most likely cause is a vascular malformation (arteriovenous malformation or cavernous angioma), which accounts for approximately 49% of intracerebral hemorrhages in young adults. 1

Diagnostic Approach

Primary Differential Diagnosis

The key causes to consider in this young, normotensive patient include:

• Vascular malformations (49% of cases): AVMs and cavernous angiomas are the leading cause of ICH in young adults, particularly those aged <20-40 years 1
• Cryptogenic hemorrhage (15%): No identifiable cause despite complete workup 1
• Cerebral venous thrombosis (5%): Can present with hemorrhage, particularly in unusual locations 1
• Sympathomimetic drug use (4%): Cocaine, amphetamines, or other stimulants 1
• Hypertensive hemorrhage (11%): Less likely given normal BP, but chronic hypertension with acute normalization is possible 1

Critical Imaging Studies Required

CT angiography (CTA) and CT venography (CTV) should be performed immediately to evaluate for underlying structural lesions including vascular malformations and cerebral venous thrombosis, as these are reasonably sensitive for identifying secondary causes of hemorrhage 2

Catheter angiography (four-vessel cerebral angiogram) should be strongly considered if initial non-invasive studies are negative or suggestive of vascular pathology, as it remains the gold standard for definitive AVM characterization 2

MRI with MRA and MRV is reasonable to provide excellent anatomic detail and identify underlying structural abnormalities, though it may be precluded by clinical instability 2

Clinical Reasoning

Why Vascular Malformation is Most Likely

• Age factor: Patients with ICH from arteriovenous malformations are significantly more likely to be aged <20 years (odds ratio 2.80), and vascular malformations remain the dominant cause through age 40 1
• Location: While thalamic hemorrhages are classically hypertensive, lobar hemorrhages (55%) are most common in young adults with vascular malformations 1
• Normal blood pressure: The absence of hypertension makes chronic hypertensive vasculopathy much less likely 1
• Clinical presentation: The triad of severe headache with homonymous hemianopia has been specifically reported in patients with vascular lesions 2, 3

Why Hypertension is Less Likely

Hypertensive ICH typically occurs in patients aged >31 years (odds ratio 3.48) and preferentially affects the basal ganglia/internal capsule (22% of young adult cases) rather than presenting as isolated thalamic hemorrhage in normotensive individuals 1

However, failure to control blood pressure is the most important preventable cause of primary ICH, so occult or poorly controlled hypertension must still be excluded 4

Additional Diagnostic Considerations

Specific Clinical Suspicions to Investigate

Clinical suspicion of secondary causes should be heightened by: 2

• Prodrome of headache or neurologic symptoms
• Unusual (non-circular) hematoma shape on imaging
• Presence of edema disproportionate to hemorrhage timing
• Presence of subarachnoid blood component

MR or CT venogram must be performed if hemorrhage location, relative edema volume, or abnormal signal in cerebral sinuses suggests cerebral venous thrombosis 2

Laboratory Evaluation

• Coagulation studies: To exclude underlying hemostatic abnormalities 2
• Toxicology screen: To identify sympathomimetic drug use (cocaine, amphetamines) 5, 1
• Complete blood count: To assess for thrombocytopenia or other hematologic disorders 2

Critical Pitfalls to Avoid

Do not assume hypertensive etiology based solely on thalamic location in a young patient – vascular malformations can occur anywhere and require definitive vascular imaging 1

Do not dismiss the need for angiography if initial CTA/MRA is negative – small vascular malformations may be missed on non-invasive imaging, and catheter angiography should be considered when clinical suspicion remains high 2

Do not overlook infectious endocarditis – while less common, severe localized headache with homonymous hemianopia has been specifically reported in patients with intracranial mycotic aneurysms and impending rupture 2