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Hydrocephalus
COMMENTS CURRENT
ON LITERATURE
Hydrocephalus R E v E R E N c E to hydrocephalus is found in the earliest medical writings, and enlargement of the head in young infants before closure of the cranial sutures was described by both Hippocrates and Vesalius. The modern concept of fluid accumulation within the ventricular system as a result of blockage in the circulation of the cerebrospinal fluid is credited largely to classic studies published by Dandy and Blackfan 1 in 1914. These investigators carried out experimental studies in animals which were based on knowledge of the cerebrospinal fluid then current: its formation in the choroid plexuses; its circulation, with passage through the aqueduct, the foramina of Luschka and Magendie to the basilar cisternae, and the cerebral and spinal subarachnoid spaces; its absorption by the pacchionian bodies, etc. In experimental animals Dandy and Blackfan 1 succeeded in producing obstruction at various locations in the system, and were able to correlate these experimental results with necropsy findings in human hydrocephalus. However, concepts of formation and physiology of spinal fluid have been modified in recent years. From investigations in both morphology and physiology, evidence has accumulated which indicates that the cells of the choroid plexuses do have a secretory function, but that they are not the sole source of cerebrospinal fluid. Sweet and his associates 2 have emphasized that elaboration of fluid occurs throughout the cerebrospinal fluid system, independent of flow from one area to another. It is produced in the choroid plexus of the ventricles, and in the subarachnoid space from the vascular bed of the pia. Isotope studies 2 have shown that absorption
of the spinal fluid takes place at multiple sites from the spinal region as well as from the cranial araehnoid villi. Fluid can be absorbed by way of the blood vessels, the perineural spaces and the ependyma. Absorption is affected by differences in pressure between the cerebrospinal fluid and the intracranial venous system, and by colloidal osmotic pressure across the bloodbrain barrier. From isotopic tracer studies in human subjects, Sweet and Locksley 2 were able to show that, with respect to water and electrolytes, resorption occurs throughout the cerebrospinal fluid system independent of flow. "These elements enter and leave the ventricles and the subarachnoid space by direct molecular capillary exchange. ''z Sweet and his co-workers consider this exchange to be a dynamic equilibrium with the plasma, similar to that characterizing other fluid compartments of the body. Protein, on the other hand, is thought to be absorbed largely from the subarachnoid space, presumably from the arachnoid villi. However, factors influencing this dynamic system and the volume of the fluid within it are not understood completely, either in the normal equilibrium or in disease states with accumulation of fluid. Several possible mechanisms responsible for the development of hydrocephalus were discussed by Ransohoff, Shulman, and Fishman a in an excellent review article in 1960. Excessive production of cerebrospinal fluid may be associated with the rare occurrence of a tumor of the choroid plexus. Poor absorption of the fluid arising from inherently defective mechanisms at the cellular or tissue level has been suggested as a possible cause, 1216
Volume 67 Number 6
but has not been established. Obstruction to the circulation of the fluid with dilatation of the channels proximal to the obstruction is considered to be the most common cause. Obstruction may be associated with neoplasms, with congenital anomalies in the system, or may be postinflammatory or posttraumatic in origin? When blockage occurs within the ventricular system, the condition has been described as "obstructive hydrocephalus." When the subaraehnoid pathways are obstructed, the term "communicating hydrocephalus" has been applied. Ransohoff and his colleagues a have suggested that since all hydrocephalus is obstructive, the terminology be simplified to identify the location, such as "intraventricular" and "extraventricular" hydrocephalus. In 1963, the concept of congenital communicating hydrocephalus was re-evaluated by Granholm and R~dberg, 4 who based their re-evaluation on a series of hydrocephalic patients for whom accurate information was available from early neonatal life. These infants were followed by lumbar pneumoencephalographic examinations. Except for a few instances, in which there had been definite evidence of meningitis, the mechanism of obstruction appeared to be perinatal hemorrhage in the intracranial portion of the subarachnoid space. Fetal and neonatM mortality studies have pointed to perinatal hypoxia as a contributing factor in intracranial hemorrhage leading to hydrocephalus of the communicating type. 5, 6 A recent report by Lourie and Berne ~ lends support to this view. Three cases are described in which delayed or secondary intracranial hemorrhage occurred and in which perinatal hypoxia appeared to be related to subsequent congenital communicating hydrocephalus. In the opinion of the authors, the findings in these cases "clearly establish intracranial bleeding into the subarachnoid cisterns at the tentorial notch ''7 as an important factor in the pathogenesis of this form of hydrocephalus. The clinical features in all three patients were similar; each child was full term and firstborn. Two of the infants were known
C o m m e n t s on current literature
12 17
to have experienced perinatal hypoxia; the third infant "survived a difficult, atonic, and prolonged labor. ''7 After recovery from the initial episodes at the time of birth, each of these infants appeared to be well. None of the mothers was aware of anything unusual about her infant's birth or first few days of life. When each patient was admitted to the neurosurgical service, at four months, seven weeks and five weeks of age respectively, the recorded history on admission carried the notation that labor and delivery were "uneventful." The common factor in these infants of perinatal distress, including hypoxia, became apparent only after a careful review of the obstetrical records, which was suggested by R. E. L. Nesbitt. The four-months-old infant died in the hospital from intraventricular hemorrhage; the other two infants developed hydrocephalus of the communicating type. Diagnosis in all three cases was made on the basis of the clinical features, with confirmation by air studies. Lourie and Berne z stress the use of pneumography in diagnosis and evaluation, stating that the findings are characteristic during each stage of the clinical course, and that by air studies it is possible to demonstrate the intermediate stage between the hypoxic subependymal hemorrhage and the communicating hydrocephalus which results. They include an adapted s schematic drawing which contrasts the sites of anoxic hemorrhages with those of hemorrhage caused by trauma. In relating natal hypoxia to delayed or recurrent hemorrhage in the subependymal region, Lourie and Berne state that perinatal hypoxic distress could be responsible for "dissolution in the subependymal matrix layer" and could result in "damage to the rich plexus of thin-walled veins in this area, thereby setting the stage for delayed hemorrhage into the cavum velum interpositum, a space normally present in young infants. ''7 The mass delineated in the cistern velum interpositum represents a hematoma which is partially encysted. Later the cistern is partially obstructed, and the hematoma may appear more like a cyst. In the experience of Lourie and Berne7 this
12 18
December 1965
Comments on current literature
mass tends to disappear as hydrocephalus progresses. These authors r e c o m m e n d t h a t t r e a t m e n t d u r i n g the a c u t e phase be d i r e c t e d t o w a r d relief of the i n t r a c r a n i a l pressure by vent r i c u l a r and l u m b a r puncture. E a r l y recognition of the mass as a clot a n d not a neoplasm is of i m p o r t a n c e in o r d e r to avoid unnecessary surgery. E v e n t u a l t r e a t m e n t of the h y d r o c e p h a l u s by shunt m u s t be d e t e r m i n e d on an individual basis, the decision in each case influenced by rnuhiple factors. T h e fact t h a t events which occur pren a t a l l y a n d in the p e r i n a t a l p e r i o d p l a y a decisive role in the life of an individual has been receiving m o r e a n d m o r e a t t e n t i o n in recent years. T h e c u r r e n t studies b y Lourie a n d Berne, 7 dealing with t h r e e cases of hydrocephalus, b r i n g into focus the need for a c c u r a t e i n f o r m a t i o n concerning the circumstances a t t e n d a n t u p o n the birth, information which parents a n d relatives often do not have. I t was only after careful evaluation of the obstetric records t h a t possible etiologic factors d u r i n g the p e r i n a t a l period were a p p a r e n t . RUSSEI,I, j . BLATTNER, .X{.D.
REFERENCES
1. Dandy, W. E., and Blackfan, K. D.: Internal hydrocephalus: An experimental, clinical and pathological study, Am. J. Dis. Child. 8: 406, 1914. 2. Sweet, W. H., and Locksley, H. B.: Formation, flow and resorption of cerebrospinal fluid in man, Proc. Soc. Exper. Biol. & Med. 84: 397, 1953;
3. 4. 5.
6.
Sweet, W. H., Brownell, G. L., Scholl, J. A., Bowsher, D. R., Benda, Philippe, and Stickley, E. E.: The formation, flow, and absorption of the cerebrospinal fluid: Newer concepts based on studies with isotopes, Chap. VIII in Res. Publ., A. Nerv. & Ment. Dis. 34: 101, 1954. Ransohoff, Jos., Shulman, Kenneth, and Fishman, R. A.: Hydrocephalus: A review of etiology and treatment, J. PEmAT. 56: 399, 1960. Granholm, L., and Rs C.: Congenital communicating hydrocephalus, J. Neurosurg. 20: 338, 1963. Gr6ntoft, O.: Intracerebral and meningeal haemorrhages in perinatally deceased infants: I. Intracerebral haemorrhages; II. Meningeal haemorrhages, Acta obst. et gynec, scandinav. 32: 308, 459, 1953. Nesbitt, R. E. L., Jr.: Perinatal loss in modern obstetrics, Philadelphia, 1957, F. A. Davis Company; Present status of maternal health and maternal care; Problems in perinatal mortality and morbidity, Proceedings of the Bi-Regional Institute on Maternity Care, School of Pub. Health, University of California, Berkeley, 1964.
7. Lourie, H., and Berne, A. S.: A contribution on the etiology and pathogenesis of congenital communicating hydrocephalus: The syndrome of delayed hemorrhage into the cisterns of the transverse cerebral fissure of infants, Neurology 15: 815, 1965; Berne, A. S., and Lourie, H.: Hemorrhage into the cistern of the velum interpositum in infants: A clinico-radiologic syndrome, Acta radiol, in press. Lourie, H., and Berne, A. S.: Radiological and clinical features of an arachnoid cyst of the quadrigeminal cistern, J. Neurol. Neurosurg. & Psychiat. 24: 374, 1961. 8. Haller, E. S., Nesbitt, R. E. L., Jr., and Anderson, G. W.: Clinical and pathological concepts of gross intracranial hemorrhage in perinatal mortality, Obst. & Gynec. Surv. 2: 179, 1956.
ON LITERATURE
Hydrocephalus R E v E R E N c E to hydrocephalus is found in the earliest medical writings, and enlargement of the head in young infants before closure of the cranial sutures was described by both Hippocrates and Vesalius. The modern concept of fluid accumulation within the ventricular system as a result of blockage in the circulation of the cerebrospinal fluid is credited largely to classic studies published by Dandy and Blackfan 1 in 1914. These investigators carried out experimental studies in animals which were based on knowledge of the cerebrospinal fluid then current: its formation in the choroid plexuses; its circulation, with passage through the aqueduct, the foramina of Luschka and Magendie to the basilar cisternae, and the cerebral and spinal subarachnoid spaces; its absorption by the pacchionian bodies, etc. In experimental animals Dandy and Blackfan 1 succeeded in producing obstruction at various locations in the system, and were able to correlate these experimental results with necropsy findings in human hydrocephalus. However, concepts of formation and physiology of spinal fluid have been modified in recent years. From investigations in both morphology and physiology, evidence has accumulated which indicates that the cells of the choroid plexuses do have a secretory function, but that they are not the sole source of cerebrospinal fluid. Sweet and his associates 2 have emphasized that elaboration of fluid occurs throughout the cerebrospinal fluid system, independent of flow from one area to another. It is produced in the choroid plexus of the ventricles, and in the subarachnoid space from the vascular bed of the pia. Isotope studies 2 have shown that absorption
of the spinal fluid takes place at multiple sites from the spinal region as well as from the cranial araehnoid villi. Fluid can be absorbed by way of the blood vessels, the perineural spaces and the ependyma. Absorption is affected by differences in pressure between the cerebrospinal fluid and the intracranial venous system, and by colloidal osmotic pressure across the bloodbrain barrier. From isotopic tracer studies in human subjects, Sweet and Locksley 2 were able to show that, with respect to water and electrolytes, resorption occurs throughout the cerebrospinal fluid system independent of flow. "These elements enter and leave the ventricles and the subarachnoid space by direct molecular capillary exchange. ''z Sweet and his co-workers consider this exchange to be a dynamic equilibrium with the plasma, similar to that characterizing other fluid compartments of the body. Protein, on the other hand, is thought to be absorbed largely from the subarachnoid space, presumably from the arachnoid villi. However, factors influencing this dynamic system and the volume of the fluid within it are not understood completely, either in the normal equilibrium or in disease states with accumulation of fluid. Several possible mechanisms responsible for the development of hydrocephalus were discussed by Ransohoff, Shulman, and Fishman a in an excellent review article in 1960. Excessive production of cerebrospinal fluid may be associated with the rare occurrence of a tumor of the choroid plexus. Poor absorption of the fluid arising from inherently defective mechanisms at the cellular or tissue level has been suggested as a possible cause, 1216
Volume 67 Number 6
but has not been established. Obstruction to the circulation of the fluid with dilatation of the channels proximal to the obstruction is considered to be the most common cause. Obstruction may be associated with neoplasms, with congenital anomalies in the system, or may be postinflammatory or posttraumatic in origin? When blockage occurs within the ventricular system, the condition has been described as "obstructive hydrocephalus." When the subaraehnoid pathways are obstructed, the term "communicating hydrocephalus" has been applied. Ransohoff and his colleagues a have suggested that since all hydrocephalus is obstructive, the terminology be simplified to identify the location, such as "intraventricular" and "extraventricular" hydrocephalus. In 1963, the concept of congenital communicating hydrocephalus was re-evaluated by Granholm and R~dberg, 4 who based their re-evaluation on a series of hydrocephalic patients for whom accurate information was available from early neonatal life. These infants were followed by lumbar pneumoencephalographic examinations. Except for a few instances, in which there had been definite evidence of meningitis, the mechanism of obstruction appeared to be perinatal hemorrhage in the intracranial portion of the subarachnoid space. Fetal and neonatM mortality studies have pointed to perinatal hypoxia as a contributing factor in intracranial hemorrhage leading to hydrocephalus of the communicating type. 5, 6 A recent report by Lourie and Berne ~ lends support to this view. Three cases are described in which delayed or secondary intracranial hemorrhage occurred and in which perinatal hypoxia appeared to be related to subsequent congenital communicating hydrocephalus. In the opinion of the authors, the findings in these cases "clearly establish intracranial bleeding into the subarachnoid cisterns at the tentorial notch ''7 as an important factor in the pathogenesis of this form of hydrocephalus. The clinical features in all three patients were similar; each child was full term and firstborn. Two of the infants were known
C o m m e n t s on current literature
12 17
to have experienced perinatal hypoxia; the third infant "survived a difficult, atonic, and prolonged labor. ''7 After recovery from the initial episodes at the time of birth, each of these infants appeared to be well. None of the mothers was aware of anything unusual about her infant's birth or first few days of life. When each patient was admitted to the neurosurgical service, at four months, seven weeks and five weeks of age respectively, the recorded history on admission carried the notation that labor and delivery were "uneventful." The common factor in these infants of perinatal distress, including hypoxia, became apparent only after a careful review of the obstetrical records, which was suggested by R. E. L. Nesbitt. The four-months-old infant died in the hospital from intraventricular hemorrhage; the other two infants developed hydrocephalus of the communicating type. Diagnosis in all three cases was made on the basis of the clinical features, with confirmation by air studies. Lourie and Berne z stress the use of pneumography in diagnosis and evaluation, stating that the findings are characteristic during each stage of the clinical course, and that by air studies it is possible to demonstrate the intermediate stage between the hypoxic subependymal hemorrhage and the communicating hydrocephalus which results. They include an adapted s schematic drawing which contrasts the sites of anoxic hemorrhages with those of hemorrhage caused by trauma. In relating natal hypoxia to delayed or recurrent hemorrhage in the subependymal region, Lourie and Berne state that perinatal hypoxic distress could be responsible for "dissolution in the subependymal matrix layer" and could result in "damage to the rich plexus of thin-walled veins in this area, thereby setting the stage for delayed hemorrhage into the cavum velum interpositum, a space normally present in young infants. ''7 The mass delineated in the cistern velum interpositum represents a hematoma which is partially encysted. Later the cistern is partially obstructed, and the hematoma may appear more like a cyst. In the experience of Lourie and Berne7 this
12 18
December 1965
Comments on current literature
mass tends to disappear as hydrocephalus progresses. These authors r e c o m m e n d t h a t t r e a t m e n t d u r i n g the a c u t e phase be d i r e c t e d t o w a r d relief of the i n t r a c r a n i a l pressure by vent r i c u l a r and l u m b a r puncture. E a r l y recognition of the mass as a clot a n d not a neoplasm is of i m p o r t a n c e in o r d e r to avoid unnecessary surgery. E v e n t u a l t r e a t m e n t of the h y d r o c e p h a l u s by shunt m u s t be d e t e r m i n e d on an individual basis, the decision in each case influenced by rnuhiple factors. T h e fact t h a t events which occur pren a t a l l y a n d in the p e r i n a t a l p e r i o d p l a y a decisive role in the life of an individual has been receiving m o r e a n d m o r e a t t e n t i o n in recent years. T h e c u r r e n t studies b y Lourie a n d Berne, 7 dealing with t h r e e cases of hydrocephalus, b r i n g into focus the need for a c c u r a t e i n f o r m a t i o n concerning the circumstances a t t e n d a n t u p o n the birth, information which parents a n d relatives often do not have. I t was only after careful evaluation of the obstetric records t h a t possible etiologic factors d u r i n g the p e r i n a t a l period were a p p a r e n t . RUSSEI,I, j . BLATTNER, .X{.D.
REFERENCES
1. Dandy, W. E., and Blackfan, K. D.: Internal hydrocephalus: An experimental, clinical and pathological study, Am. J. Dis. Child. 8: 406, 1914. 2. Sweet, W. H., and Locksley, H. B.: Formation, flow and resorption of cerebrospinal fluid in man, Proc. Soc. Exper. Biol. & Med. 84: 397, 1953;
3. 4. 5.
6.
Sweet, W. H., Brownell, G. L., Scholl, J. A., Bowsher, D. R., Benda, Philippe, and Stickley, E. E.: The formation, flow, and absorption of the cerebrospinal fluid: Newer concepts based on studies with isotopes, Chap. VIII in Res. Publ., A. Nerv. & Ment. Dis. 34: 101, 1954. Ransohoff, Jos., Shulman, Kenneth, and Fishman, R. A.: Hydrocephalus: A review of etiology and treatment, J. PEmAT. 56: 399, 1960. Granholm, L., and Rs C.: Congenital communicating hydrocephalus, J. Neurosurg. 20: 338, 1963. Gr6ntoft, O.: Intracerebral and meningeal haemorrhages in perinatally deceased infants: I. Intracerebral haemorrhages; II. Meningeal haemorrhages, Acta obst. et gynec, scandinav. 32: 308, 459, 1953. Nesbitt, R. E. L., Jr.: Perinatal loss in modern obstetrics, Philadelphia, 1957, F. A. Davis Company; Present status of maternal health and maternal care; Problems in perinatal mortality and morbidity, Proceedings of the Bi-Regional Institute on Maternity Care, School of Pub. Health, University of California, Berkeley, 1964.
7. Lourie, H., and Berne, A. S.: A contribution on the etiology and pathogenesis of congenital communicating hydrocephalus: The syndrome of delayed hemorrhage into the cisterns of the transverse cerebral fissure of infants, Neurology 15: 815, 1965; Berne, A. S., and Lourie, H.: Hemorrhage into the cistern of the velum interpositum in infants: A clinico-radiologic syndrome, Acta radiol, in press. Lourie, H., and Berne, A. S.: Radiological and clinical features of an arachnoid cyst of the quadrigeminal cistern, J. Neurol. Neurosurg. & Psychiat. 24: 374, 1961. 8. Haller, E. S., Nesbitt, R. E. L., Jr., and Anderson, G. W.: Clinical and pathological concepts of gross intracranial hemorrhage in perinatal mortality, Obst. & Gynec. Surv. 2: 179, 1956.