Signs and Symptoms of Brain Herniation in Hemorrhagic Stroke
Brain herniation presents with rapid neurological deterioration characterized by declining level of consciousness, pupillary abnormalities, and respiratory pattern changes—recognition of these signs is critical as mortality reaches 50-70% even with aggressive intervention. 1
Early Warning Signs
Altered level of consciousness is the earliest and most sensitive indicator of impending herniation. 2 This manifests as:
- Progressive lethargy and decreased arousal 2
- Behavioral changes and confusion 2
- Deteriorating Glasgow Coma Scale score 3
Headache accompanied by vomiting suggests rising intracranial pressure, particularly when the patient was previously alert. 2 Vomiting is more common in hemorrhagic stroke than ischemic stroke or subarachnoid hemorrhage. 2
Progressive Neurological Deterioration
As herniation advances, patients develop a constellation of brainstem compression signs 2:
- Worsening motor deficits, including new pyramidal signs on the previously non-hemiplegic side 3
- Pupillary changes (asymmetry, dilation, loss of light reactivity)—this is a late sign indicating imminent herniation 2, 3
- Extensor posturing (decerebrate or decorticate rigidity) 3
- Respiratory pattern abnormalities including hyperventilation, Cheyne-Stokes breathing, or apneic episodes 2, 3
Critical Late Signs
Once pupillary abnormalities develop, the patient is at immediate risk of death from brainstem herniation. 2 Late manifestations include:
- Bradycardia (Cushing's reflex) 2
- Hypertensive surges attempting to maintain cerebral perfusion 4
- Respiratory arrest 2
- Seizures and incontinence 2
Timing and Clinical Context
Peak risk for herniation occurs 72-96 hours after hemorrhagic stroke onset when cerebral edema reaches maximum. 1 However, in large hemorrhages (>40 cm³), deterioration can occur within the first 24-48 hours. 5
Subfalcian herniation is the most common type (occurring in approximately 46% of patients with ganglionic hemorrhage who develop herniation), followed by uncal herniation. 3 Combined herniation patterns carry the worst prognosis. 3
High-Risk Patient Characteristics
Patients with hypertension, diabetes, and cardiovascular disease face compounded risk 1:
- Hematoma volume >30-40 cm³ is the strongest predictor of herniation and death 5, 3
- Ventricular extension of hemorrhage independently predicts mortality 2
- Hydrocephalus from CSF pathway obstruction 2
- Glasgow Coma Scale score <8 on admission 3
Critical Pitfall to Avoid
Papilledema is often absent because herniation progression can be so rapid that optic disc swelling does not have time to develop. 2 Do not wait for papilledema to diagnose elevated intracranial pressure—rely on clinical deterioration and imaging findings instead. 2
Hyperventilation and extensor rigidity are clinical signs of critically elevated ICP (>30 mm Hg), indicating herniation is imminent or already occurring. 6, 3 Once these signs appear, mortality approaches 80% with conventional treatment alone. 6
Radiographic Correlates
CT or MRI findings that correlate with clinical herniation include 2, 3:
- Midline shift (horizontal displacement of septum pellucidum or pineal gland)
- Frontal horn compression or effacement of basal cisterns
- Mass effect from the edema-hematoma complex
- Tonsillar descent through the foramen magnum (in severe cases)
The edema-hematoma complex size directly correlates with herniation risk, GCS score, pupillary abnormalities, and one-month mortality. 3