Disorders of Intracranial Pressure



Disorders of Intracranial Pressure





Brain Edema


Definition

Increased brain volume due to increase in water and sodium content.


Major Types of Brain Edema

Features of three major forms of cerebral edema (vasogenic, cytotoxic, interstitial) summarized in Table 50.1.


Other Types of Brain Edema



  • Ischemic brain edema: cellular edema in first few minutes to hours, then vasogenic edema (hours to days).


  • Fulminant hepatic encephalopathy: due to acute hepatocellular failure (acute hepatitis, Reye syndrome). Progressive stupor and coma, severe intracranial hypertension; often fatal. Imaging: global brain edema without contrast enhancement.


  • Granulocytic brain edema: due to pus accumulation. Seen with brain abscess, purulent meningitis. Simultaneous features of cellular, vasogenic, sometimes interstitial edema.


Treatment

Dictated by cause of edema (see Table 50.1).


Glucocorticoids

Reduce vasogenic edema in hours by normalizing endothelial cell permeability; effective for edema of brain tumor, abscess.

Common regimen: dexamethasone 10 mg intravenous starting dose, followed by 4 mg administered four times a day. Gastric hemorrhage most significant complication.

Use in spinal cord injury discussed in Chapter 65.









Table 50.1 Features of Various Types of Brain Edema
























































  Vasogenic Cytotoxic Interstitial (Hydrocephalic)
Pathogenesis Increased capillary permeability Cellular swelling (glial, neuronal, endothelial) Increased brain fluid
Location of edema Chiefly white matter Gray and white matter Chiefly periventricular white matter
Clinical disorders Brain tumor, abscess, infarction, contusion, hemorrhage, lead encephalopathy
Ischemia
Purulent meningitis (granulocytic edema)		 Hypoxia, hypo-osmolality (e.g., water intoxication)
Ischemia
Purulent meningitis (granulocytic edema), fulminant hepatic encephalopathy		 Obstructive hydrocephalus, pseudotumor (benign intracranial hypertension)
Purulent meningitis
Clinical manifestations Focal neurologic deficits, disturbances of consciousness, severe intracranial hypertension Stupor, coma, asterixis, myoclonus, focal or generalized seizures Dementia and gait disorder with advanced hydrocephalus
CT, MRI Abnormal, with contrast enhancement Often normal, without contrast enhancement Enlarged ventricles, loss of sulci, periventricular abnormalities
CSF Increased protein Normal protein LP may be contraindicated
EEG changes Focal slowing common Generalized slowing EEG often normal
Therapeutic Effects
 Steroids Beneficial in brain tumor, abscess Not effective (except perhaps in fulminant hepatic encephalopathy) Uncertain effectiveness
 Osmotherapy (e.g., mannitol) Reduces volume of normal brain tissue only, acutely Reduces brain volume acutely Rarely useful
Modified from Fishman RA. Cerebrospinal fluid in diseases of the nervous system. Philadelphia: WB Saunders, 1992:116–137.

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Jul 27, 2016 | Posted by in NEUROLOGY | Comments Off on Disorders of Intracranial Pressure

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