Hydrocephalus
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Basics
Description
- Increased volume of CSF in cranial cavity
- Cerebral atrophy also leads to increased CSF in the cranial vault but CSF pressure is not increased (normal pressure hydrocephalus)
- Obstructive hydrocephalus is the most common form:
- Obstruction is within ventricular system or in subarachnoid space
- Acute obstructive hydrocephalus may cause rapid rise in intracranial pressure (ICP), rapidly leading to death or permanent cerebral damage
- Nonobstructive hydrocephalus causes subacute symptoms and is a potentially treatable form of dementia
- Also described as “communicating” and “noncommunicating”:
- Communicating hydrocephalus: Flow of CSF is blocked after it exits the ventricles (ventricles still “communicate”)
- Noncommunicating hydrocephalus: Flow of CSF blocked along 1 or more of the passages connecting the ventricles (ventricles do not “communicate”)
Etiology
- Obstructive hydrocephalus:
- Obstruction of:
- Aqueduct of Sylvius (most common, both lateral ventricles and third ventricle dilated, fourth ventricle is spared)
- Aqueductal stenosis can be congenital or acquired (tumor, subarachnoid hemorrhage, post meningitis, idiopathic)
- Foramen of Monro (lateral ventricles dilated, usually both but may be unilateral)
- Foramina of Luschka and Magendie (fourth ventricle blocked followed by third and lateral ventricles)
- Subarachnoid space around brainstem (postinfectious or postsubarachnoid hemorrhage [post-SAH] entire system dilated)
- Acute presentations usually secondary to CSF shunt blockage, SAH, or severe head trauma
- Obstruction of:
- Nonobstructive hydrocephalus:
- Normal pressure hydrocephalus:
- Increased intracranial volume of CSF without intracranial hypertension
- Increased ventricular size on CT (without volume loss as in atrophy)
- Sometimes called “chronic hydrocephalus”
- Usually occurs due to inadequate CNS absorption
- Normal pressure hydrocephalus:
Pediatric Considerations
Pediatric hydrocephalus:
- Congenital hydrocephalus owing to neonatal hemorrhage, congenital malformations, or acquired postmeningitis secondary to subarachnoid scarring around brainstem
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Basics
Description
- Increased volume of CSF in cranial cavity
- Cerebral atrophy also leads to increased CSF in the cranial vault but CSF pressure is not increased (normal pressure hydrocephalus)
- Obstructive hydrocephalus is the most common form:
- Obstruction is within ventricular system or in subarachnoid space
- Acute obstructive hydrocephalus may cause rapid rise in intracranial pressure (ICP), rapidly leading to death or permanent cerebral damage
- Nonobstructive hydrocephalus causes subacute symptoms and is a potentially treatable form of dementia
- Also described as “communicating” and “noncommunicating”:
- Communicating hydrocephalus: Flow of CSF is blocked after it exits the ventricles (ventricles still “communicate”)
- Noncommunicating hydrocephalus: Flow of CSF blocked along 1 or more of the passages connecting the ventricles (ventricles do not “communicate”)
Etiology
- Obstructive hydrocephalus:
- Obstruction of:
- Aqueduct of Sylvius (most common, both lateral ventricles and third ventricle dilated, fourth ventricle is spared)
- Aqueductal stenosis can be congenital or acquired (tumor, subarachnoid hemorrhage, post meningitis, idiopathic)
- Foramen of Monro (lateral ventricles dilated, usually both but may be unilateral)
- Foramina of Luschka and Magendie (fourth ventricle blocked followed by third and lateral ventricles)
- Subarachnoid space around brainstem (postinfectious or postsubarachnoid hemorrhage [post-SAH] entire system dilated)
- Acute presentations usually secondary to CSF shunt blockage, SAH, or severe head trauma
- Obstruction of:
- Nonobstructive hydrocephalus:
- Normal pressure hydrocephalus:
- Increased intracranial volume of CSF without intracranial hypertension
- Increased ventricular size on CT (without volume loss as in atrophy)
- Sometimes called “chronic hydrocephalus”
- Usually occurs due to inadequate CNS absorption
- Normal pressure hydrocephalus:
Pediatric Considerations
Pediatric hydrocephalus:
- Congenital hydrocephalus owing to neonatal hemorrhage, congenital malformations, or acquired postmeningitis secondary to subarachnoid scarring around brainstem
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