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A unifying theory for the definition and classification of hydrocephalus.
Childs Nerv Syst. 1994 Jan; 10(1):2-12.CN

Abstract

If the cerebrospinal fluid (CSF) is considered to be all the fluid (liquid), other than blood or the derivatives of its breakdown, that is normally contained within the brain, its cavities, and its spaces, this could be regarded as "brain fluid" in its most elemental form. "Pathological increases in intracranial CSF volume, independent of hydrostatic or barometric pressure", then, could be considered a definition of hydrocephalus. The observation of significant episodic variation in intracranial pressure (ICP) suggests the necessity of substituting the concept of "time-related pressure variations" for the older one of "level of pressure" in patients with defective ICP control mechanisms. It has been assumed that the subarachnoid channels are the first CSF compartment to dilate in response to the hydrocephalic process, reducing the CSF pressure and thereby establishing an equilibrium. When the equilibrium is disturbed, with progressive dilation of the subarachnoid channels, the increase in CSF pressure is transmitted to the ventricular system, resulting in its dilation (extraprenchymal hydrocephalus). Progressive ventricular dilation causes cerebral edema (intraparenchymal hydrocephalus) and obliterates the subarachnoid spaces as the hemispheres are compressed against the dura, resulting in apparent "internal hydrocephalus" in the absence of "external hydrocephalus". Thus, subarachnoid space or ventricular dilation occur as a result of intermittent increases in extraparenchymal CSF volume: the primary pressure force emanating from the subarachnoid and subdural spaces and from the intraventricular compartment. Hydrocephalus, therefore, may be present in a child who does not yet have dilated ventricles but in whom both CSF volume and pressure are increased. Thus, it becomes obvious that the term internal hydrocephalus is of little significance, since increases in intraparenchymal fluid--cerebral edema--cause the same volumetric changes as increases in intraventricular fluid volume. I suggest that hydrocephalus is a pathologic increase in intracranial CSF ("brain fluid") volume, whether intra- or extraparenchymal, independent of hydrostatic or barometric pressure. It may be classified as (1) intraparenchymal (cerebral edema) and (2) extraparenchymal, with the extraparenchymal types subclassified into subarachnoid, cisternal, and intraventricular forms.

Authors+Show Affiliations

Department of Pediatric Neurosurgery, University of Rome La Sapienza, Italy.

Pub Type(s)

Journal Article
Review

Language

eng

PubMed ID

8194058

Citation

Raimondi, A J.. "A Unifying Theory for the Definition and Classification of Hydrocephalus." Child's Nervous System : ChNS : Official Journal of the International Society for Pediatric Neurosurgery, vol. 10, no. 1, 1994, pp. 2-12.
Raimondi AJ. A unifying theory for the definition and classification of hydrocephalus. Childs Nerv Syst. 1994;10(1):2-12.
Raimondi, A. J. (1994). A unifying theory for the definition and classification of hydrocephalus. Child's Nervous System : ChNS : Official Journal of the International Society for Pediatric Neurosurgery, 10(1), 2-12.
Raimondi AJ. A Unifying Theory for the Definition and Classification of Hydrocephalus. Childs Nerv Syst. 1994;10(1):2-12. PubMed PMID: 8194058.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A unifying theory for the definition and classification of hydrocephalus. A1 - Raimondi,A J, PY - 1994/1/1/pubmed PY - 1994/1/1/medline PY - 1994/1/1/entrez SP - 2 EP - 12 JF - Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery JO - Childs Nerv Syst VL - 10 IS - 1 N2 - If the cerebrospinal fluid (CSF) is considered to be all the fluid (liquid), other than blood or the derivatives of its breakdown, that is normally contained within the brain, its cavities, and its spaces, this could be regarded as "brain fluid" in its most elemental form. "Pathological increases in intracranial CSF volume, independent of hydrostatic or barometric pressure", then, could be considered a definition of hydrocephalus. The observation of significant episodic variation in intracranial pressure (ICP) suggests the necessity of substituting the concept of "time-related pressure variations" for the older one of "level of pressure" in patients with defective ICP control mechanisms. It has been assumed that the subarachnoid channels are the first CSF compartment to dilate in response to the hydrocephalic process, reducing the CSF pressure and thereby establishing an equilibrium. When the equilibrium is disturbed, with progressive dilation of the subarachnoid channels, the increase in CSF pressure is transmitted to the ventricular system, resulting in its dilation (extraprenchymal hydrocephalus). Progressive ventricular dilation causes cerebral edema (intraparenchymal hydrocephalus) and obliterates the subarachnoid spaces as the hemispheres are compressed against the dura, resulting in apparent "internal hydrocephalus" in the absence of "external hydrocephalus". Thus, subarachnoid space or ventricular dilation occur as a result of intermittent increases in extraparenchymal CSF volume: the primary pressure force emanating from the subarachnoid and subdural spaces and from the intraventricular compartment. Hydrocephalus, therefore, may be present in a child who does not yet have dilated ventricles but in whom both CSF volume and pressure are increased. Thus, it becomes obvious that the term internal hydrocephalus is of little significance, since increases in intraparenchymal fluid--cerebral edema--cause the same volumetric changes as increases in intraventricular fluid volume. I suggest that hydrocephalus is a pathologic increase in intracranial CSF ("brain fluid") volume, whether intra- or extraparenchymal, independent of hydrostatic or barometric pressure. It may be classified as (1) intraparenchymal (cerebral edema) and (2) extraparenchymal, with the extraparenchymal types subclassified into subarachnoid, cisternal, and intraventricular forms. SN - 0256-7040 UR - https://www.unboundmedicine.com/medline/citation/8194058/A_unifying_theory_for_the_definition_and_classification_of_hydrocephalus_ L2 - https://doi.org/10.1007/bf00313578 DB - PRIME DP - Unbound Medicine ER -