What are the signs and symptoms of significant Intracranial Pressure (ICP)?

Signs and Symptoms of Significant Intracranial Pressure (ICP)

The clinical signs of elevated ICP include headache, papilledema, nausea, and vomiting in the early phases, followed by stupor and coma, pupillary changes, hemiparesis or quadriparesis, posturing and respiratory abnormalities, and eventually cardiopulmonary arrest. 1

Early Signs and Symptoms

• Headache - often worse in the morning or with position changes 1, 2
• Papilledema - swelling of the optic disc visible on fundoscopic examination 1
• Nausea and vomiting - typically projectile and not related to food intake 1, 2
• Changes in behavior with minimal change in level of consciousness (Grade I encephalopathy) 3
• Gross disorientation, drowsiness, possibly asterixis, inappropriate behavior (Grade II encephalopathy) 3

Progressive Signs and Symptoms

• Marked confusion, incoherent speech, sleeping most of the time but arousable to vocal stimuli (Grade III encephalopathy) 3
• Stupor progressing to coma 1
• Pupillary changes - including anisocoria (unequal pupils) or bilateral mydriasis (dilated pupils) 3
• Hemiparesis or quadriparesis 1
• Decorticate or decerebrate posturing 3, 1

Late Signs (Cushing's Triad)

• Hypertension - often with widened pulse pressure 3
• Bradycardia - irregular heart rate 3
• Irregular respirations - abnormal breathing patterns 3, 1

Imaging Findings Associated with Elevated ICP

• Disappearance of cerebral ventricles on CT scan 3
• Brain midline shift over 5 mm 3
• Intracerebral hematoma volume over 25 mL 3
• Compression of basal cisterns - the best radiological sign of intracranial hypertension 3
  • Absence of basal cisterns is associated with ICP higher than 30 mmHg in more than 70% of cases 3

Severity Assessment

• An ICP of 20-40 mmHg is associated with a 3.95 times higher risk of mortality and poor neurological outcome 3
• Above an ICP of 40 mmHg, mortality risk increases 6.9-fold 3
• Comatose state, unresponsive to pain (Grade IV encephalopathy) indicates severe intracranial hypertension 3

Important Clinical Considerations

• The classic Cushing's triad (hypertension, bradycardia, and irregular respirations) is not uniformly present and typically appears late in the course of elevated ICP 3
• CT of the brain does not reliably demonstrate evidence of cerebral edema, especially at early stages 3
• Normal CT findings cannot completely exclude the risk of subsequent intracranial hypertension in comatose patients, though the incidence is lower (0-8%) 3
• Traumatic subarachnoid hemorrhage is associated with a higher risk of intracranial hypertension 3

Pitfalls in Diagnosis

• Relying solely on CT findings can be misleading, as visibility of basal cisterns does not completely exclude intracranial hypertension 3
• Waiting for the full Cushing's triad to appear before intervention may result in delayed treatment, as these signs typically manifest late in the course 3
• Symptoms and signs of elevated ICP are neither sufficiently sensitive nor specific, requiring a high index of suspicion for early recognition 2
• Transcranial Doppler findings (such as increased pulsatility index) require confirmation by other means to reliably indicate intracranial hypertension 3

Early recognition of these signs and symptoms is crucial for timely intervention to prevent cerebral hypoperfusion and possible brain death 1, 4.