Intracranial Hypertension, Hydrocephalus, and CSF Disorders
Physiology and recognition
Intracranial hypertension results when the volume of brain, blood, and CSF exceeds the fixed cranial vault. Understand the pressure-volume curve: compliance is exhausted before pressure rises steeply, so deterioration can be sudden. Recognize clinical signs (headache, vomiting, altered consciousness, papilledema, sixth nerve palsy, sunsetting eyes in infants) and monitor ICP and CPP. Elevated ICP with a plateau waveform (Lundberg waves) signals critically reduced compliance.
Hydrocephalus and CSF disorders
Distinguish communicating from noncommunicating hydrocephalus and know that an external ventricular drain both measures pressure and drains CSF. Understand shunt malfunction as a recurring emergency: vomiting, headache, lethargy, and possibly infection. Recognize that over-drainage causes headache from low pressure. Know that CSF analysis (cell count, glucose, protein, culture) is central to diagnosing meningitis and that opening pressure matters.
Management principles
Use tiered therapy: head midline and elevated, avoid neck compression, maintain oxygenation and normocapnia, sedation and analgesia, osmotic therapy (hypertonic saline or mannitol), CSF drainage, and decompressive surgery when refractory. Avoid hypotonic fluids. Corticosteroids are useful for tumor-associated edema but not for traumatic injury.
Traps
Questions test that mannitol causes diuresis and possible rebound, that hypertonic saline requires sodium monitoring, and that a normal ICP at one moment does not exclude intracranial hypertension.
Rule of thumb
Treat the child and the trend: worsening exam plus rising ICP warrants escalating therapy, not watchful waiting.