Neurologic Effects of Basal Ganglia Hemorrhage
Basal ganglia hemorrhage causes devastating neurologic injury through direct mass effect, increased intracranial pressure, and secondary brain injury mechanisms, with the specific deficits determined by the precise location and volume of bleeding within this critical motor and cognitive control center. 1
Primary Mechanisms of Neurologic Injury
Basal ganglia hemorrhage injures brain tissue through two distinct pathways 1:
- Direct pressure effects from the acutely expanding hematoma cause local compression of surrounding brain tissue and widespread mechanical injury from increased intracranial pressure, hydrocephalus, or herniation 1
- Secondary injury mechanisms include cerebral edema, inflammation, and biochemical toxicity from blood products such as hemoglobin, iron, and thrombin 1
- Early hematoma expansion occurs in 30-40% of patients and independently predicts poor neurologic outcome 2
Specific Neurologic Manifestations
The basal ganglia comprise multiple subcortical nuclei that form an integrated functional unit controlling motor function, cognition, and behavior 3:
- Motor deficits are the hallmark presentation, typically manifesting as contralateral hemiparesis or hemiplegia due to disruption of motor pathways 4, 5
- Altered consciousness ranging from confusion to coma occurs with larger hemorrhages, particularly those exceeding 40 cm³ 2
- Cognitive impairment results from disruption of frontostriatal circuits involved in executive function 3
- Seizures may occur, though prophylactic antiseizure medications are not routinely recommended unless seizures are documented 2
Volume-Dependent Severity
Hematoma volume is the strongest predictor of mortality and functional outcome 2:
- 40 cm³ represents a critical threshold with baseline 30-day mortality of 25-50% 2
- Larger volumes cause greater mass effect, increased intracranial pressure, and higher risk of herniation 1
- Hematoma expansion in the first 24 hours dramatically worsens prognosis and occurs in 30-40% of cases 2
Location-Specific Considerations
The basal ganglia location indicates specific pathophysiology and prognosis 6:
- Hypertensive etiology is most common, reflecting chronic small vessel disease (arteriolosclerosis) affecting penetrating arterioles 1, 6
- Deep territory hemorrhages (basal ganglia, thalamus, brainstem) have different recurrence patterns than lobar hemorrhages, with recurrence rates of 2.1-3.7% per year 1
- Bilateral basal ganglia hemorrhage is extremely rare but carries exceptionally poor prognosis with high mortality 4, 7, 8, 3
Prognostic Implications
Neurologic recovery depends on multiple factors 2:
- Survivors often have moderate to severe persistent functional deficits including motor impairment, cognitive dysfunction, and dependency in activities of daily living 2
- Early prognostication is unreliable and should not guide decisions about withdrawal of support in the first 48 hours 1, 2
- Aggressive full care is recommended initially, as early DNR orders create self-fulfilling prophecies of poor outcome 1
Critical Pitfall to Avoid
Never institute DNR orders or withdraw support in the first 48 hours, as current prognostication methods are biased by failure to account for the influence of early care limitations, and many patients can achieve meaningful recovery with aggressive guideline-concordant therapy 1, 2