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Positive-contrast computed cranial tomographic encephalography in children
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Positive-Contrast Computed Cranial Tomographic Encephalography in Children S t e v e n J. G o l d s t e i n
and John W. Walsh
University of Kentucky College of Medicine, Lexington, Kentucky
Goldstein SJ, Walsh JW. Positive-contrast computed cranial tomographic encephalography in children. Surg Neurol 1983; 19:174-80.
Positive-contrast computed tomographic encephalography is a safe and effective technique for the evaluation of intraventricular, paraventricular, and cystic intracranial lesions in children. It provides dynamic as well as morphologic information not readily available by routine computed tomographic scanning alone. Our experience with the use of this technique in 21 children forms the basis for this paper. KEYWORDS: Encephalography; Ventriculography; Computed tomography; Metrizamide; Porencephalic cyst; Arachnoid cyst
Since the advent o f computed cranial tomography (CT), there has been a dramatic decline in the use of invasive neuroradiologic procedures in the pediatric population. Cerebral angiography is only occasionally required for the evaluation of vascular intracranial lesions, and pneumoencephalography is no longer performed in most university medical centers. Plain film ventriculography is also only rarely used in the age o f high-resolution CT scanning [ 1,4-7,12]. Occasionally routine CT scanning will demonstrate a lesion that requires further radiologic evaluation before possible surgical intervention. Is the lesion paraventricular or intraventricular? If cystic in nature does it communicate with the subarachnoid spaces or ventricular system? Is there obstructive ventriculomegaly? Positivecontrast computed tomographic encephalography is a safe and effective method for investigating these clinical problems. It permits complete preoperative evaluation of the pertinent aspects of these relatively unusual intracranial lesions. This report reviews our recent experience with this modality in 21 infants and children. Address reprint requests to: Steven J. Goldstein, M.D., Department of Diagnostic Radiology, HX-315, University of Kentucky College of Medicine, 800 Rose Street, Lexington, Kentucky 40536. This paper was presented at the annual meeting of the American Roentgen Ray Society, New Orleans, Louisiana, May 1982.
© 1983 by Elsevier Science Publishing Co., Inc.
Materials and Methods Twenty-two positive-contrast computed tomographic encephalograms were performed in 21 children between September 1978 and October 1981. The patients ranged from 1 week to 9 years o f age. T h e r e were 16 males and five females. Before positive-contrast computed tomographic encephalography all patients had routine CT scans with and without intravenously administered contrast-medium enhancement. In each case the initial scan revealed either a cystic intracranial lesions, an intraventricular lesion, or paraventricular lesion that potentially required surgical intervention (Table 1). Positive-contrast computed tomographic encephalography was used to define the nature of these mass lesions and to determine the presence and site of obstructive hydrocephalus if a concomitant ventricular enlargement was demonstrated. All studies were performed by introducing watersoluble contrast media either directly into the ventricular system or into the lesion itself, if it was cystic and peripherially located. All examinations were performed with the use of local anesthesia and intramuscular sedation; general anesthesia was not required. In most cases the contrast medium was introduced directly into the preexisting shunt system or through a 22-gauge spinal needle that was placed through the coronal suture or anterior fontanelle. Two to three cubic centimeters of Conray 60 was used in the first four patients and 2 - 5 ml o f metrizamide (diluted to a concentration of 180 mg o f iodine/ml o f metrizamide solution) was the contrast agent used in all the remaining examinations. After contrast instillation all patients were scanned in the axial position on a Technicare Delta 50 or a Technicare Delta 2020 CT scanner. In seven o f the patients coronal scans were obtained as well to confirm or further evaluate the findings revealed by the axial study.
Results In all 22 studies in which contrast was successfully instilled into either the ventricular system or intracranial 0090-3019/83/020174-07503.00
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Table 1. Patient Data Case Number
Age
Sex
Diagnosis
Management
1
13 m o
M
Arachnoid cyst--sylvian cistern
Excision
2
7 wk
M
Choroid plexus h e m a t o m a Aqueductal stenosis
Biopsy and s h u n t
3
2 yr
M
Arachnoid cyst--quadrigeminal cistern
Excision
4
9 mo
F
Loculated fourth ventricle Aqueductal stenosis Porencephalic cyst
Bilimbed s h u n t
5
2 yr
M
Ventriculomegaly Syringobulbia
Shunt
6
10 yr
M
Pontine glioma
Biopsy and radiation therapy
7
5 yr
M
Arachnoid cyst cerebellar cistern
Excision
8
4 mo
M
Megacisterna magna
--
9
1 wk
F
D a n d y - W a l k e r cyst Agenesis o f corpus callosum Ventriculomegaly
Shunt
10
3 mo
M
Retrocerebellar cyst
Excision
11
9 yr
M
Aqueductal stenosis Multiloculated ventriculomegaly
Supportive care
12
8 yr
F
Arachnoid cyst--interhemispheric
Shunt
13
2 wk
M
Ventriculomegaly Porencephalic cyst
Shunt
14
1 yr
M
Porencephalic cyst
Shunt
15
1 wk
M
Hydranencephaly
Supportive care
16
1 mo
M
Porencephalic cyst Agenesis of corpus callosum
Shunt
17
1 yr
M
Multiloculated subdural effusions
Shunt
18
4 yr
F
Choroid plexus cyst
Excision
19
11 yr
M
Arachnoid cyst--sylvian cistern
Excision
20
6 mo
M
Ventriculomegaly Porencephalic cyst
Excision Shunt
21
2 mo
F
Aqueductal stenosis Porencephalic cyst
Shunt
Abbreviations: wk = week; mo - month; yr = year
cystic lesion, the CT scans proved to be of excellent diagnostic value. (In one case the contrast medium was injected into a shunt and failed to opacify the ventricular system, presumably because it passed distally into the peritoneum. This patient was successfully examined at a later date after direct ventricular puncture). Eighteen of the 21 patients underwent surgical procedures following the studies. In each of these cases either the decision to operate or the type of procedure performed was directly influenced by the findings demonstrated with positive-contrast computed tomographic encephalography. The study was instrumental in deciding not
to operate on the remaining three patients who were treated conservatively. T h e final diagnosis in these patients were megacisterna magnum, hydranencephaly, and multiloculated hydrocephalus. Surgical treatment was felt to play no role in the treatment of any of these patients after their diagnoses were confirmed by the positive-contrast c o m p u t e d tomographic encephalograms. N o seizures or significant temperature elevations occurred in any o f the patients after the scans were p e r f o r m e d , and in no instance was there any significant neurological deterioration demonstrated after the administration o f contrast medium.
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Representative Case Reports Case 1 This 13-year-old boy presented with right lower extremity weakness that had been present since birth. Physical examination revealed flexion posturing of the right upper extremity and weakness and mild atrophy of the right lower extremity. The routine CT scan demonstrated a cystic lesion with a cerebrospinal fluid (CSF) density in the region of the left sylvian fissure, which did not appear to have a mass effect or thin the adjacent calvarium. The cyst also appeared to communicate with the atrial region of the left lateral ventricle suggesting the diagnosis of a porencephalic cyst (Figure 1A). Positive-contrast computed tomographic encephalography, however, revealed that the lesion failed to communicate with the ventricular system (Figure 1B). This led to the diagnosis of an arachnoid cyst. A left temporal craniotomy was performed, and the cystic lesion was dissected away from the adjacent brain without complication. The pathologic examination confirmed the diagnosis of sylvian fissure arachnoid cyst.
Case 2 This 7-week-old male infant was admitted to the neurosurgery service because ofmegalencephaly. Except for the large head and transillumination of the calvarium, the physical examination was normal. There was no history of seizures. The initial CT scan revealed moderate enlargement of the lateral and third ventricles thought to be secondary to aqueductal stenosis. O f equal concern
Figure 1. (A) Computed tomography scan without contrast-medium enhancement: This axial scan demonstrates a CSF density lesion that appears to communicate with the atrial portion of the left lateral ventricle. There is minimal i f any thinning of the bone, and there is no obvious mass effect secondary to the cystic lesion. On the basis of these computed tomographic findings the preliminary diagnosis was a porencephalic cyst. (B) Positive-contrast computed tomographic encephalopathy. This scan done after the instillation of metrizamide directly into the cyst reveals that the lesion occupying the sylvian fissure represents an arachnoid cyst rather than a communicating porencephalic cyst. This finding was confirmed surgically.
Goldstein and Walsh
was the presence of an enhancing lesion that appeared to lie adjacent to the wall of the body of the left lateral ventricle (Figure 2A). The scan without contrast revealed a small nidus of calcium centrally placed within the mass. Positive-contrast CT encephalography confirmed the suspected intraventricular location of the mass lesion as well as the diagnosis of aqueductal stenosis (Figures, 2 B, C, and D). At operation the left lateral ventricular mass was resected and a ventriculoperitoneal shunt was placed. Pathologic examination of the mass revealed an organizing hematoma of the choroid plexus, which was partially calcified and contained areas of scattered fibrosis.
Case 3 This 2-year-old boy was referred to us for evaluation because he had had a large head since birth, and had experienced mild delays in developmental milestones. Physical examination was negative except for an abnormally large head (circumference greater than the 98 percentile) and a left esotropia. Routine CT scanning revealed marked enlargement of the lateral and third ventricles with a normal size fourth ventricle. The initial scan also demonstrated a peculiar appearing collection of CSF behind and adjacent to the quadrigeminal plate extending posteriorly over the vermis (Figure 3A). On the basis of the preliminary CT scan an enlarged superior cerebellar cistern or cisterna magna could not be distinguished from a loculated arachnoid cyst of the quadrigeminal plate. The large size of the lesion and the lack of a linear contrast-enhancing density within or sur-
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Figure 2. (A) Computed tomography scan enhanced with intravenously administered contrastmedium enhancement: This study reveals moderate enlargement of the lateral ventricles as well as an enhancing calcified mass lesion in the trigone of the left lateral ventricle (arrow~, (B,C) Positilecontrast computed tomographic encephalopathy, axial and coronal views: The intraventricular location of the calcified mass lesion ¢arrow) is established by the axial CT scan performed after instillation of metrizamide (B) and confirmed by the coronal study (C). Final pathologic diagnosis was a hemorrhagic, fibrotic choroid plexus. (D) Axial positive-contrast tomographic encephalography, fourth ventricular level." No metrizamide is present in the fourth ventricle, confirming the diagnosis of aqueductal stenosis.
rounding it as described by Just and Goldenberg [8] made the diagnosis of an enlarged cisterna magna unlikely. In order to avoid the potentially disasterous consequences of tonsillar herniation, it was elected to study this lesion from above with computed tomographic ventriculography rather than from below via a lumbar injection of metrizamide. The study using contrast medium demonstrated opacification of the lateral and third ventricles with nonfilling of the aqueduct, fourth ventricle and the cyst (Figure 3B). This constellation of findings could best be accounted for by postulating that the aqueduct of Sylvius was being compressed by the
cystic mass behind the quadrigeminal plate. A subsequent craniotomy confirmed the presence of a loculated quadrigeminal plate arachnoid cyst.
Case 4 This 9-month-old female infant had a CT-documented germinal matrix and left frontal lobe hemorrhage shortly after birth. Because of progressive ventricular enlargement she underwent ventriculoperitoneal shunting at age 4 days. Her present admission was due to rapid enlargement of her head. Physical examination revealed
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Goldstein and Walsh
Figure 3. (A) Intravenously administered contrast-medium enhanced CT scan: There is lateral and third ventricular enlargement present secondary to aqueductal obstruction. Also noted is an abnormally large supravermian cistern (arrows) extending posteriorly behind the cerebellarhemispheres. (B) Positivecontrast tomographic encephalography: The intraventricular contrast-medium enhanced study confirms the lack of communication between the ventricular system and the supracerebellar collection of CSF.
a tense anterior fontanelle and dilated scalp veins. A preliminary CT scan demonstrated moderate ventricular enlargement of the third and lateral ventricles as well as a large collection of CSF density occupying almost the entire posterior fossa (Figure 4 A and B) which was not present on her original CT scan. Also noted was a lesion of CSF density in the left frontal lobe that appeared to communicate with the frontal horn of the lateral ventricle and was thought to be a porencephalic cyst. Metrizamide was injected into the ventricular system and a CT scan was subsequently obtained. It confirmed the presence of a left frontal porencephaly and demonstrated no communication between the cyst in the posterior fossa and the remainder of the ventricular system (Figure 4B). A posterior fossa craniectomy was undertaken revealing that the large cyst was a markedly dilated fourth ventricle thereby confirming the suspected diagnosis of a trapped fourth ventricle. Her supratentorial shunt was revised and an additional limb was placed into the fourth ventricle with excellent clinical results.
Case 5 This 2 year-old-boy was born with a meningomyelocele and moderate enlargement of the cerebral ventricles for which a ventriculoperitoneal shunt had been placed. His present admission was necessitated because of the new onset of respiratory insufficiency and swallowing difficulty thought to be secondary to pontine compression. A routine CT scan demonstrated adequate decompression of the lateral and third ventricles and a large midline cystic structure of CSF density occupying the region of
the fourth ventricle, which extended inferiorly to the level of the foramen magnum. A metrizamide-enhanced, computed tomographic encephalogram was performed, which revealed prompt opacification of the small third and lateral ventricles without filling of the cyst in the posterior fossa. The patient subsequently underwent a suboccipital craniotomy that revealed the presence of a markedly dilated fourth ventricle in direct communication with a syrinx of the medulla oblongata and high cervical spinal cord. The syringobulbia was shunted with some moderate return of neurologic function.
Discussion Rapid enlargement of circumference of the head, apneic spells, hypotonia, and seizures constitute the most common indication for cranial CT scanning in the nontraumatized pediatric patient. In a small percentage of cases the routine CT scan reveals a cystic, ventricular, or paraventricular lesion that may require surgical intervention because of mass effect or associated ventricular obstruction. Positive-contrast computed tomographic encephalography has proved to be quite valuable in those selected cases in which definitive preoperative characterization of the lesion beyond that obtainable by routine CT scanning is deemed necessary. It is most useful in defining the origin of solid lesions, whether adjacent to or within the ventricular system, and to define possible communication between cystic lesions and the ventricles or the subarachnoid spaces. Evaluation of small intraaxial lesions of the midbrain and pons may be facilitated by the use of positive-contrast CT encephalography. This is especially true if high-resolution, late-
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Figure 4. (A) Routine C T scan without contrast medium enhancement, lateral ventricular level: This study demonstrates a ventriculoperitoneal shunt tip well within the body of the enlarged left ventricle. The left frontal lobe has also been replaced by a porencephalic cyst of CSF density. (B) Computed tomography scan without contrast-medium enhancement, posterior fossa level: There is a large mass lesion of CSF density occupying almost the entire
posterior fossa. (C) Positive-contrast tomographic encephalography: This study demonstrates lack of communication between the cystic mass in the posterior fossa and the remainder of the ventricular system. On the basis of the positive-contrast tomographic encephalography, the original shunt was revised and a new limb was placed into the enlarged, loculated fourth ventricle.
generation CT is not available to assist in the assessment of minor displacement or distortion of the fourth ventricle and aqueduct. In the rare instance in which repeated infection results in either subarachnoid or intraventricular septations, positive-contrast computed tomographic encephalography is valuable in the preoperative assessment of the number and location of shunts that should be placed to effectively decompress any closed CSF compartments. Positive-contrast computed tomographic encephalography is also very helpful in the demonstration o f lesions that are obliquely oriented to the plane of the routine axial or coronal CT sections. Intracranial, water-soluble contrast has been employed both by Strand et al [10] and Drayer et al [3] in the pediatric population. Both investigators performed the majority of their studies without the use of general anesthesia, and each advocated metrizamide as the contrast agent of choice. Strand introduced the contrast agent through a ventricular shunt system in all but two of his cases. Plain film ventriculography was then used as the primary radiographic study. In about onefifth of the cases, the plain radiographs were supplemented by either CT scans or multidirectional tomography. Strand reported that in 18% of his patients the plain film ventriculography was "less than optimal" [ 10].
Drayer et al introduced contrast medium into the subarachnoid spaces via the lumbar route and then encouraged its passage into the intracranial basal cisterns by placing the patient in a 60 ° Trendelenberg position for 60 seconds. Each of his patients then underwent a CT scan with excellent visualization of the metrizamidefilled subarachnoid spaces. Although the fourth ventricle was consistently filled with contrast medium, by using his method opacification of the lateral and third ventricles was not uniformly obtained. Introduction o f the contrast agent directly into the ventricular system or into the lesion itself if peripheral and cystic has certain definite advantages over the lumbar route. It guarantees excellent opacification and characterization o f the regions of primary interest especially when coupled with the high-resolution capabilities of CT rather than plain film imaging or multidirectional tomography. Direct intracranial instillation of the contrast medium also permits smaller doses than are required when the lumbar route is used. The direct intracranial approach may also be safer than the lumbar route especially if routine CT scanning has already demonstrated a space-occupying intracranial mass lesion that might produce transtentorial herniation after lumbar puncture.
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The safety of intracranial subarachnoid and intraventricular metrizamide has been well established in both the laboratory and clinical practice [2,3,9-11]. Headaches, nausea, and vomiting were only rarely encountered by both Drayer et al [3] and Strand et al [10] in their pediatric patients. In neither series did any of the children receiving the subarachnoid or intraventricular metrizamide have any seizures. Most investigators conclude that in comparison with angiography and pneumoencephalography, metrizamide encephalography and cisternography has substantially lower morbidity [2,3,911]. Our experience supports this conclusion as well, because no significant adverse reactions were encountered in our series of 21 patients. As general anesthesia is not required to perform positive-contrast computed tomographic encephalography its risks are obviated as well [3,10]. Positive-contrast computed tomographic encephalography has proven to be quite valuable in those instances in which the exact nature of an intracranial cystic, intraventricular, or paraventricular lesion is not apparent from the routine CT scan. In 18 of our cases (92%) the results directly influenced either the decision to operate or the type of surgical procedure to be performed. In the remaining three cases (8%) the patients were treated conservatively based upon the findings. If judicially used in the proper circumstances, positive-contrast computed tomographic encephalography provides a valuable neuroradiologic technique that has both enhanced diagnostic accuracy and has little or no demonstrated morbidity in the pediatric patient.
Goldstein and Walsh
The authors wish to thank Vicki Hatcher, Glenna Statzer and Jane Vickers for the assistance in manuscript preparation. References 1. Berger PE, Kirks DR, Gilday DL, Fitz CR, Harwood-Nash DC. Computerized tomography in infants and children: intracranial neoplasms. AJR 1976;127:129-37. 2. Corrales M, Tapia J. Encephalography with metriazmide. Neuroradiology 1977;13:249-54. 3. Drayer BP, Rosenbaum AE, Reigel DB, Bank WO, Deeb ZL. Metrizamide computed tomography cisternography: pediatric applications. Radiology 1977;124:349-57. 4. Epstein F, Naidich TP, Chase NE, DricheffII, LinnJP, Bansohoff J. Role of computed tomography in diagnosis and treatment of common neurosurgical problems of infancy and childhood. Childs Brain 1976;2:111-3l. 5. Goldstein SJ, Young B, Markesberry WR. Congenital malignant gliosarcoma. AJNR 1981;2:475-6. 6. Gomez MR, Reese DF. The usefulness of computed tomography in pediatric neurology. Univ Mich Med Cent J 1976;42: 105-11. 7. Harwood-Nash DC, Breckbill DL. Computed tomography in children. A new diagnostic technique. J Pediatr 1976;89:343-57. 8. Just NW, Goldenberg M. Computed tomography of the enlarged cisterna magna. Radiology 1979; 131:385-91. 9. Servo A, Halonon V. Double-contrast ventriculography with oxygen and water-soluble positive contrast medium, metrizamide (Amipaque). J Neurosurg 1979;51:211-8. 10. Strand RD, Baker RA, Ordia IJ, Arkins TJ. Metriazmide ventriculography and computed tomography in lesions about the third ventricle. Radiology 1978;128:405-10. 11. Suzuki S, Ito K, Iwabuchi T. Ventriculography with non-ionic water-soluble contrast medium, Amipaque (metrizamide), J Neurosurg 1977;47:79-85. 12. Tadmor R, Harwood-Nash DC, Savoiardo M, Scotti G, Musgrave M, Fitz CR, Chuang S. Brain tumors in the first two years of life: CT diagnosis. AJNR; 1:411-7.
Surg Neurol 1983;19:174-80
Positive-Contrast Computed Cranial Tomographic Encephalography in Children S t e v e n J. G o l d s t e i n
and John W. Walsh
University of Kentucky College of Medicine, Lexington, Kentucky
Goldstein SJ, Walsh JW. Positive-contrast computed cranial tomographic encephalography in children. Surg Neurol 1983; 19:174-80.
Positive-contrast computed tomographic encephalography is a safe and effective technique for the evaluation of intraventricular, paraventricular, and cystic intracranial lesions in children. It provides dynamic as well as morphologic information not readily available by routine computed tomographic scanning alone. Our experience with the use of this technique in 21 children forms the basis for this paper. KEYWORDS: Encephalography; Ventriculography; Computed tomography; Metrizamide; Porencephalic cyst; Arachnoid cyst
Since the advent o f computed cranial tomography (CT), there has been a dramatic decline in the use of invasive neuroradiologic procedures in the pediatric population. Cerebral angiography is only occasionally required for the evaluation of vascular intracranial lesions, and pneumoencephalography is no longer performed in most university medical centers. Plain film ventriculography is also only rarely used in the age o f high-resolution CT scanning [ 1,4-7,12]. Occasionally routine CT scanning will demonstrate a lesion that requires further radiologic evaluation before possible surgical intervention. Is the lesion paraventricular or intraventricular? If cystic in nature does it communicate with the subarachnoid spaces or ventricular system? Is there obstructive ventriculomegaly? Positivecontrast computed tomographic encephalography is a safe and effective method for investigating these clinical problems. It permits complete preoperative evaluation of the pertinent aspects of these relatively unusual intracranial lesions. This report reviews our recent experience with this modality in 21 infants and children. Address reprint requests to: Steven J. Goldstein, M.D., Department of Diagnostic Radiology, HX-315, University of Kentucky College of Medicine, 800 Rose Street, Lexington, Kentucky 40536. This paper was presented at the annual meeting of the American Roentgen Ray Society, New Orleans, Louisiana, May 1982.
© 1983 by Elsevier Science Publishing Co., Inc.
Materials and Methods Twenty-two positive-contrast computed tomographic encephalograms were performed in 21 children between September 1978 and October 1981. The patients ranged from 1 week to 9 years o f age. T h e r e were 16 males and five females. Before positive-contrast computed tomographic encephalography all patients had routine CT scans with and without intravenously administered contrast-medium enhancement. In each case the initial scan revealed either a cystic intracranial lesions, an intraventricular lesion, or paraventricular lesion that potentially required surgical intervention (Table 1). Positive-contrast computed tomographic encephalography was used to define the nature of these mass lesions and to determine the presence and site of obstructive hydrocephalus if a concomitant ventricular enlargement was demonstrated. All studies were performed by introducing watersoluble contrast media either directly into the ventricular system or into the lesion itself, if it was cystic and peripherially located. All examinations were performed with the use of local anesthesia and intramuscular sedation; general anesthesia was not required. In most cases the contrast medium was introduced directly into the preexisting shunt system or through a 22-gauge spinal needle that was placed through the coronal suture or anterior fontanelle. Two to three cubic centimeters of Conray 60 was used in the first four patients and 2 - 5 ml o f metrizamide (diluted to a concentration of 180 mg o f iodine/ml o f metrizamide solution) was the contrast agent used in all the remaining examinations. After contrast instillation all patients were scanned in the axial position on a Technicare Delta 50 or a Technicare Delta 2020 CT scanner. In seven o f the patients coronal scans were obtained as well to confirm or further evaluate the findings revealed by the axial study.
Results In all 22 studies in which contrast was successfully instilled into either the ventricular system or intracranial 0090-3019/83/020174-07503.00
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Table 1. Patient Data Case Number
Age
Sex
Diagnosis
Management
1
13 m o
M
Arachnoid cyst--sylvian cistern
Excision
2
7 wk
M
Choroid plexus h e m a t o m a Aqueductal stenosis
Biopsy and s h u n t
3
2 yr
M
Arachnoid cyst--quadrigeminal cistern
Excision
4
9 mo
F
Loculated fourth ventricle Aqueductal stenosis Porencephalic cyst
Bilimbed s h u n t
5
2 yr
M
Ventriculomegaly Syringobulbia
Shunt
6
10 yr
M
Pontine glioma
Biopsy and radiation therapy
7
5 yr
M
Arachnoid cyst cerebellar cistern
Excision
8
4 mo
M
Megacisterna magna
--
9
1 wk
F
D a n d y - W a l k e r cyst Agenesis o f corpus callosum Ventriculomegaly
Shunt
10
3 mo
M
Retrocerebellar cyst
Excision
11
9 yr
M
Aqueductal stenosis Multiloculated ventriculomegaly
Supportive care
12
8 yr
F
Arachnoid cyst--interhemispheric
Shunt
13
2 wk
M
Ventriculomegaly Porencephalic cyst
Shunt
14
1 yr
M
Porencephalic cyst
Shunt
15
1 wk
M
Hydranencephaly
Supportive care
16
1 mo
M
Porencephalic cyst Agenesis of corpus callosum
Shunt
17
1 yr
M
Multiloculated subdural effusions
Shunt
18
4 yr
F
Choroid plexus cyst
Excision
19
11 yr
M
Arachnoid cyst--sylvian cistern
Excision
20
6 mo
M
Ventriculomegaly Porencephalic cyst
Excision Shunt
21
2 mo
F
Aqueductal stenosis Porencephalic cyst
Shunt
Abbreviations: wk = week; mo - month; yr = year
cystic lesion, the CT scans proved to be of excellent diagnostic value. (In one case the contrast medium was injected into a shunt and failed to opacify the ventricular system, presumably because it passed distally into the peritoneum. This patient was successfully examined at a later date after direct ventricular puncture). Eighteen of the 21 patients underwent surgical procedures following the studies. In each of these cases either the decision to operate or the type of procedure performed was directly influenced by the findings demonstrated with positive-contrast computed tomographic encephalography. The study was instrumental in deciding not
to operate on the remaining three patients who were treated conservatively. T h e final diagnosis in these patients were megacisterna magnum, hydranencephaly, and multiloculated hydrocephalus. Surgical treatment was felt to play no role in the treatment of any of these patients after their diagnoses were confirmed by the positive-contrast c o m p u t e d tomographic encephalograms. N o seizures or significant temperature elevations occurred in any o f the patients after the scans were p e r f o r m e d , and in no instance was there any significant neurological deterioration demonstrated after the administration o f contrast medium.
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Representative Case Reports Case 1 This 13-year-old boy presented with right lower extremity weakness that had been present since birth. Physical examination revealed flexion posturing of the right upper extremity and weakness and mild atrophy of the right lower extremity. The routine CT scan demonstrated a cystic lesion with a cerebrospinal fluid (CSF) density in the region of the left sylvian fissure, which did not appear to have a mass effect or thin the adjacent calvarium. The cyst also appeared to communicate with the atrial region of the left lateral ventricle suggesting the diagnosis of a porencephalic cyst (Figure 1A). Positive-contrast computed tomographic encephalography, however, revealed that the lesion failed to communicate with the ventricular system (Figure 1B). This led to the diagnosis of an arachnoid cyst. A left temporal craniotomy was performed, and the cystic lesion was dissected away from the adjacent brain without complication. The pathologic examination confirmed the diagnosis of sylvian fissure arachnoid cyst.
Case 2 This 7-week-old male infant was admitted to the neurosurgery service because ofmegalencephaly. Except for the large head and transillumination of the calvarium, the physical examination was normal. There was no history of seizures. The initial CT scan revealed moderate enlargement of the lateral and third ventricles thought to be secondary to aqueductal stenosis. O f equal concern
Figure 1. (A) Computed tomography scan without contrast-medium enhancement: This axial scan demonstrates a CSF density lesion that appears to communicate with the atrial portion of the left lateral ventricle. There is minimal i f any thinning of the bone, and there is no obvious mass effect secondary to the cystic lesion. On the basis of these computed tomographic findings the preliminary diagnosis was a porencephalic cyst. (B) Positive-contrast computed tomographic encephalopathy. This scan done after the instillation of metrizamide directly into the cyst reveals that the lesion occupying the sylvian fissure represents an arachnoid cyst rather than a communicating porencephalic cyst. This finding was confirmed surgically.
Goldstein and Walsh
was the presence of an enhancing lesion that appeared to lie adjacent to the wall of the body of the left lateral ventricle (Figure 2A). The scan without contrast revealed a small nidus of calcium centrally placed within the mass. Positive-contrast CT encephalography confirmed the suspected intraventricular location of the mass lesion as well as the diagnosis of aqueductal stenosis (Figures, 2 B, C, and D). At operation the left lateral ventricular mass was resected and a ventriculoperitoneal shunt was placed. Pathologic examination of the mass revealed an organizing hematoma of the choroid plexus, which was partially calcified and contained areas of scattered fibrosis.
Case 3 This 2-year-old boy was referred to us for evaluation because he had had a large head since birth, and had experienced mild delays in developmental milestones. Physical examination was negative except for an abnormally large head (circumference greater than the 98 percentile) and a left esotropia. Routine CT scanning revealed marked enlargement of the lateral and third ventricles with a normal size fourth ventricle. The initial scan also demonstrated a peculiar appearing collection of CSF behind and adjacent to the quadrigeminal plate extending posteriorly over the vermis (Figure 3A). On the basis of the preliminary CT scan an enlarged superior cerebellar cistern or cisterna magna could not be distinguished from a loculated arachnoid cyst of the quadrigeminal plate. The large size of the lesion and the lack of a linear contrast-enhancing density within or sur-
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Figure 2. (A) Computed tomography scan enhanced with intravenously administered contrastmedium enhancement: This study reveals moderate enlargement of the lateral ventricles as well as an enhancing calcified mass lesion in the trigone of the left lateral ventricle (arrow~, (B,C) Positilecontrast computed tomographic encephalopathy, axial and coronal views: The intraventricular location of the calcified mass lesion ¢arrow) is established by the axial CT scan performed after instillation of metrizamide (B) and confirmed by the coronal study (C). Final pathologic diagnosis was a hemorrhagic, fibrotic choroid plexus. (D) Axial positive-contrast tomographic encephalography, fourth ventricular level." No metrizamide is present in the fourth ventricle, confirming the diagnosis of aqueductal stenosis.
rounding it as described by Just and Goldenberg [8] made the diagnosis of an enlarged cisterna magna unlikely. In order to avoid the potentially disasterous consequences of tonsillar herniation, it was elected to study this lesion from above with computed tomographic ventriculography rather than from below via a lumbar injection of metrizamide. The study using contrast medium demonstrated opacification of the lateral and third ventricles with nonfilling of the aqueduct, fourth ventricle and the cyst (Figure 3B). This constellation of findings could best be accounted for by postulating that the aqueduct of Sylvius was being compressed by the
cystic mass behind the quadrigeminal plate. A subsequent craniotomy confirmed the presence of a loculated quadrigeminal plate arachnoid cyst.
Case 4 This 9-month-old female infant had a CT-documented germinal matrix and left frontal lobe hemorrhage shortly after birth. Because of progressive ventricular enlargement she underwent ventriculoperitoneal shunting at age 4 days. Her present admission was due to rapid enlargement of her head. Physical examination revealed
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Figure 3. (A) Intravenously administered contrast-medium enhanced CT scan: There is lateral and third ventricular enlargement present secondary to aqueductal obstruction. Also noted is an abnormally large supravermian cistern (arrows) extending posteriorly behind the cerebellarhemispheres. (B) Positivecontrast tomographic encephalography: The intraventricular contrast-medium enhanced study confirms the lack of communication between the ventricular system and the supracerebellar collection of CSF.
a tense anterior fontanelle and dilated scalp veins. A preliminary CT scan demonstrated moderate ventricular enlargement of the third and lateral ventricles as well as a large collection of CSF density occupying almost the entire posterior fossa (Figure 4 A and B) which was not present on her original CT scan. Also noted was a lesion of CSF density in the left frontal lobe that appeared to communicate with the frontal horn of the lateral ventricle and was thought to be a porencephalic cyst. Metrizamide was injected into the ventricular system and a CT scan was subsequently obtained. It confirmed the presence of a left frontal porencephaly and demonstrated no communication between the cyst in the posterior fossa and the remainder of the ventricular system (Figure 4B). A posterior fossa craniectomy was undertaken revealing that the large cyst was a markedly dilated fourth ventricle thereby confirming the suspected diagnosis of a trapped fourth ventricle. Her supratentorial shunt was revised and an additional limb was placed into the fourth ventricle with excellent clinical results.
Case 5 This 2 year-old-boy was born with a meningomyelocele and moderate enlargement of the cerebral ventricles for which a ventriculoperitoneal shunt had been placed. His present admission was necessitated because of the new onset of respiratory insufficiency and swallowing difficulty thought to be secondary to pontine compression. A routine CT scan demonstrated adequate decompression of the lateral and third ventricles and a large midline cystic structure of CSF density occupying the region of
the fourth ventricle, which extended inferiorly to the level of the foramen magnum. A metrizamide-enhanced, computed tomographic encephalogram was performed, which revealed prompt opacification of the small third and lateral ventricles without filling of the cyst in the posterior fossa. The patient subsequently underwent a suboccipital craniotomy that revealed the presence of a markedly dilated fourth ventricle in direct communication with a syrinx of the medulla oblongata and high cervical spinal cord. The syringobulbia was shunted with some moderate return of neurologic function.
Discussion Rapid enlargement of circumference of the head, apneic spells, hypotonia, and seizures constitute the most common indication for cranial CT scanning in the nontraumatized pediatric patient. In a small percentage of cases the routine CT scan reveals a cystic, ventricular, or paraventricular lesion that may require surgical intervention because of mass effect or associated ventricular obstruction. Positive-contrast computed tomographic encephalography has proved to be quite valuable in those selected cases in which definitive preoperative characterization of the lesion beyond that obtainable by routine CT scanning is deemed necessary. It is most useful in defining the origin of solid lesions, whether adjacent to or within the ventricular system, and to define possible communication between cystic lesions and the ventricles or the subarachnoid spaces. Evaluation of small intraaxial lesions of the midbrain and pons may be facilitated by the use of positive-contrast CT encephalography. This is especially true if high-resolution, late-
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Figure 4. (A) Routine C T scan without contrast medium enhancement, lateral ventricular level: This study demonstrates a ventriculoperitoneal shunt tip well within the body of the enlarged left ventricle. The left frontal lobe has also been replaced by a porencephalic cyst of CSF density. (B) Computed tomography scan without contrast-medium enhancement, posterior fossa level: There is a large mass lesion of CSF density occupying almost the entire
posterior fossa. (C) Positive-contrast tomographic encephalography: This study demonstrates lack of communication between the cystic mass in the posterior fossa and the remainder of the ventricular system. On the basis of the positive-contrast tomographic encephalography, the original shunt was revised and a new limb was placed into the enlarged, loculated fourth ventricle.
generation CT is not available to assist in the assessment of minor displacement or distortion of the fourth ventricle and aqueduct. In the rare instance in which repeated infection results in either subarachnoid or intraventricular septations, positive-contrast computed tomographic encephalography is valuable in the preoperative assessment of the number and location of shunts that should be placed to effectively decompress any closed CSF compartments. Positive-contrast computed tomographic encephalography is also very helpful in the demonstration o f lesions that are obliquely oriented to the plane of the routine axial or coronal CT sections. Intracranial, water-soluble contrast has been employed both by Strand et al [10] and Drayer et al [3] in the pediatric population. Both investigators performed the majority of their studies without the use of general anesthesia, and each advocated metrizamide as the contrast agent of choice. Strand introduced the contrast agent through a ventricular shunt system in all but two of his cases. Plain film ventriculography was then used as the primary radiographic study. In about onefifth of the cases, the plain radiographs were supplemented by either CT scans or multidirectional tomography. Strand reported that in 18% of his patients the plain film ventriculography was "less than optimal" [ 10].
Drayer et al introduced contrast medium into the subarachnoid spaces via the lumbar route and then encouraged its passage into the intracranial basal cisterns by placing the patient in a 60 ° Trendelenberg position for 60 seconds. Each of his patients then underwent a CT scan with excellent visualization of the metrizamidefilled subarachnoid spaces. Although the fourth ventricle was consistently filled with contrast medium, by using his method opacification of the lateral and third ventricles was not uniformly obtained. Introduction o f the contrast agent directly into the ventricular system or into the lesion itself if peripheral and cystic has certain definite advantages over the lumbar route. It guarantees excellent opacification and characterization o f the regions of primary interest especially when coupled with the high-resolution capabilities of CT rather than plain film imaging or multidirectional tomography. Direct intracranial instillation of the contrast medium also permits smaller doses than are required when the lumbar route is used. The direct intracranial approach may also be safer than the lumbar route especially if routine CT scanning has already demonstrated a space-occupying intracranial mass lesion that might produce transtentorial herniation after lumbar puncture.
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The safety of intracranial subarachnoid and intraventricular metrizamide has been well established in both the laboratory and clinical practice [2,3,9-11]. Headaches, nausea, and vomiting were only rarely encountered by both Drayer et al [3] and Strand et al [10] in their pediatric patients. In neither series did any of the children receiving the subarachnoid or intraventricular metrizamide have any seizures. Most investigators conclude that in comparison with angiography and pneumoencephalography, metrizamide encephalography and cisternography has substantially lower morbidity [2,3,911]. Our experience supports this conclusion as well, because no significant adverse reactions were encountered in our series of 21 patients. As general anesthesia is not required to perform positive-contrast computed tomographic encephalography its risks are obviated as well [3,10]. Positive-contrast computed tomographic encephalography has proven to be quite valuable in those instances in which the exact nature of an intracranial cystic, intraventricular, or paraventricular lesion is not apparent from the routine CT scan. In 18 of our cases (92%) the results directly influenced either the decision to operate or the type of surgical procedure to be performed. In the remaining three cases (8%) the patients were treated conservatively based upon the findings. If judicially used in the proper circumstances, positive-contrast computed tomographic encephalography provides a valuable neuroradiologic technique that has both enhanced diagnostic accuracy and has little or no demonstrated morbidity in the pediatric patient.
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The authors wish to thank Vicki Hatcher, Glenna Statzer and Jane Vickers for the assistance in manuscript preparation. References 1. Berger PE, Kirks DR, Gilday DL, Fitz CR, Harwood-Nash DC. Computerized tomography in infants and children: intracranial neoplasms. AJR 1976;127:129-37. 2. Corrales M, Tapia J. Encephalography with metriazmide. Neuroradiology 1977;13:249-54. 3. Drayer BP, Rosenbaum AE, Reigel DB, Bank WO, Deeb ZL. Metrizamide computed tomography cisternography: pediatric applications. Radiology 1977;124:349-57. 4. Epstein F, Naidich TP, Chase NE, DricheffII, LinnJP, Bansohoff J. Role of computed tomography in diagnosis and treatment of common neurosurgical problems of infancy and childhood. Childs Brain 1976;2:111-3l. 5. Goldstein SJ, Young B, Markesberry WR. Congenital malignant gliosarcoma. AJNR 1981;2:475-6. 6. Gomez MR, Reese DF. The usefulness of computed tomography in pediatric neurology. Univ Mich Med Cent J 1976;42: 105-11. 7. Harwood-Nash DC, Breckbill DL. Computed tomography in children. A new diagnostic technique. J Pediatr 1976;89:343-57. 8. Just NW, Goldenberg M. Computed tomography of the enlarged cisterna magna. Radiology 1979; 131:385-91. 9. Servo A, Halonon V. Double-contrast ventriculography with oxygen and water-soluble positive contrast medium, metrizamide (Amipaque). J Neurosurg 1979;51:211-8. 10. Strand RD, Baker RA, Ordia IJ, Arkins TJ. Metriazmide ventriculography and computed tomography in lesions about the third ventricle. Radiology 1978;128:405-10. 11. Suzuki S, Ito K, Iwabuchi T. Ventriculography with non-ionic water-soluble contrast medium, Amipaque (metrizamide), J Neurosurg 1977;47:79-85. 12. Tadmor R, Harwood-Nash DC, Savoiardo M, Scotti G, Musgrave M, Fitz CR, Chuang S. Brain tumors in the first two years of life: CT diagnosis. AJNR; 1:411-7.