What are the clinical signs and symptoms of increased intracranial pressure?

Signs and Symptoms of Elevated Intracranial Pressure

Elevated intracranial pressure presents with a predictable progression from early symptoms (headache, nausea, vomiting, visual disturbances) to late signs (altered consciousness, pupillary abnormalities, posturing) that constitute a neurological emergency requiring immediate intervention. 1

Early Clinical Manifestations

Headache is the most common presenting symptom, typically progressively severe and worsening with Valsalva maneuvers (coughing, straining, bending forward). 2, 1 The headache phenotype is highly variable and may mimic other primary headache disorders. 2

Visual symptoms include:

• Transient visual obscurations (brief episodes of bilateral or unilateral vision darkening lasting seconds) 2
• Blurred vision 2, 1
• Diplopia (double vision), particularly horizontal diplopia from sixth nerve palsy 2, 1
• Visual field defects 1

Papilledema (optic disc swelling visible on fundoscopic examination) is a hallmark finding, though it may be absent in acute-onset elevated ICP. 2, 1 This represents a critical diagnostic sign when present. 2

Nausea and vomiting, particularly projectile vomiting without preceding nausea, are common early symptoms. 1

Additional early symptoms include:

• Pulsatile tinnitus (whooshing sound synchronous with pulse) 2
• Dizziness 2
• Neck and back pain 2
• Cognitive disturbances 2

Late and Critical Signs

Altered mental status represents progression to dangerous ICP levels, ranging from mild confusion to progressive decline in consciousness, stupor, and eventually coma. 1, 3 Changes in level of consciousness are an early warning sign of critically elevated ICP, whereas pupillary changes represent a late sign. 4

Pupillary abnormalities indicate advanced elevation and impending herniation. 1, 3 These are late findings suggesting imminent danger. 4

Motor findings include:

• Focal neurological deficits and hemiparesis 1, 3
• Abnormal posturing (decorticate or decerebrate) 1, 3
• Deterioration in motor function 4

Cranial nerve palsies, particularly sixth nerve palsy causing incomitant esotropia (typically greater at distance with possible abduction nystagmus), can occur from nerve stretching. 4, 1

Respiratory abnormalities and changes in respiratory pattern indicate brainstem compression. 4, 3

Vital sign changes including alterations in blood pressure and heart rate occur as ICP rises. 4 The blood pressure may rise to maintain adequate cerebral perfusion pressure as ICP increases. 4

Special Population Considerations

In pediatric patients, particularly infants with open fontanelles, specific signs include:

• Bulging fontanelle 1
• Increased head circumference 1
• Separation of cranial sutures 1

Diagnostic Thresholds

Opening pressure ≥25 cm H₂O (≥250 mm H₂O) measured during lumbar puncture in the lateral decubitus position with legs extended confirms elevated ICP. 2 In general clinical practice, ICP >20 mm Hg measured via invasive monitoring is considered elevated and requires treatment. 5, 3

Critical Clinical Pitfalls

Absence of papilledema does not exclude elevated ICP, especially in acute presentations where disc swelling has not yet developed. 1 Relying solely on fundoscopic examination can lead to missed diagnoses. 1

Focal neurologic signs or impaired mentation should prompt neuroimaging (CT or MRI) before lumbar puncture to exclude mass lesions that could precipitate herniation with CSF removal. 4

The progression from early to late signs can be rapid, and any patient with suspected elevated ICP showing declining consciousness, new pupillary changes, or posturing requires immediate intervention as these indicate imminent herniation and potential brain death. 1, 3