J Neurosurg 77:230-235, 1992
Atretic cephalocele: the tip of the iceberg JUAN F. MARTINEZoLAGE, M.D., JOAQUiN SOLA, M.D., CARLOS CASAS, M.D., MAXIMO POZA, M.D., MARIA J. ALMAGRO,M.D., AND DIEGO G. GIRONA, M.D.
Regional Service of Neurosurgery and Sections of Neuropathology and Neuropediatrics, University Hospital Virgen de Arrixaca, El Palmar, Murcia, Spain Atretic cephalocele appears as an unimportant and benign lesion. This malformation consists of meningeal and vestigial tissues (arachnoid, glial, or central nervous system rests). The authors report the findings in 16 cases (seven parietal and nine occipital) of rudimentary cephaloceles. Twelve patients presented with associated brain abnormalities detected by either computerized tomography (CT) or magnetic resonance imaging (MR). Nine lesions also exhibited an anomalous vascular component demonstrated by CT or MR imaging or at surgery. The existence of this tiny malformation in five cases was the main diagnostic clue to a severe complex of cerebral anomalies, namely cerebro-oculomuscular (Walker-Warburg) syndrome. An occipital location of the atretic cephalocele was associated with the worst prognosis, with only two children developing normally. However, a parietal location carried a better prognosis, which is contrary to the outcome reported in the current literature. The authors classify atretic cephaloceles into two types based on histological examination of the surgical specimens, and suggest that these types represent different stages in the development of this malformation. It is concluded that, in the evaluation of the atretic cephalocele, the neurosurgeon is obliged to proceed to a detailed neuroradiological study of the patient and that the prognosis does not depend on the existence of the cephalocele itself, but rather on associated "occult" brain anomalies. KEY WORDS atretic cephalocele encephalocele 9 cranial meningoeele
EPHALOCELESare congenital herniations of intracranial structures through a skull defect. ~3 In the case of cranial meningocele, the sac contains meninges and cerebrospinal fluid (CSF). If the sac also contains central nervous system (CNS) tissue, then the term "encephalocele" is used. James and Lassman ~ introduced the concept of an abortive form of meningomyelocele in 1972 with the term "meningocele manqu6," meaning spontaneous arrest in the development of that malformation. Several authors have used the expression "atretic," "abortive," "occult," and "rudimentary cephalocele," 2,6,7.16referring to a skin-covered subsealp lesion that consists of meninges and rests of glial and/or CNS tissues. The gross appearance of this malformation is that of an unimportant and benign lesion. McLaurin j~ and Yokota, et al., ~6 have stressed the high frequency of associated cerebral malformations with atretic encephaloceles. Recently, Drapkin" described a more favorable prognosis for this anomaly, distinct from the true encephalocele. We report our experience with 16 cases of this "inoffensive" congenital defect. To our knowledge, this report constitutes the largest published series of atretic cephalocele cases with a long follow-up period.
C
230
cerebro-oculomuscular syndrome 9 hydrocephalus 9 Walker-Warburg syndrome
Clinical Material and Methods
Patient Population The clinical records of 32 pediatric patients with cephaloceles who were admitted to our hospital from 1976 to October, 1991, were reviewed. Sixteen of these cases corresponded to previous descriptions of atretic cephaloeele. The clinical data were analyzed, including patient's age, sex, antenatal and family history, presentation, localization of the lesion, and the results of neurological and general examinations. Plain skull radiographs and computerized tomography (CT) scans were obtained for all patients. Contrast-enhanced CT was performed in eight children. Magnetic resonance (MR) imaging was obtained for only six patients. The surgical records were also investigated. Pathological Classification Atretic cephalocele was classified into two categories depending on the pathological features (Fig. 1). In a Type 1 cephalocele, the dural covering consists mainly of arachnoid tissue found almost exclusively at the lesion stalk and accompanied by a cluster of anomalous blood vessels (Fig. 2 left). It is difficult to ascertain if J. Neurosurg. / Volume 77/August, 1992
Atretic cephalocele at the stalk of the malformation but they extend, as a nel, toward the lesion dome. It was only in this second type that we encountered ectopic foci of neural or glial elements (Fig. 2 righl).
Follow- Up Evaluation Outcomes were determined by reviewing the outpatient records of the children or by direct-mail or telephone inquiry of their parents. Functional results were evaluated in terms of psychomotor development and neurological examination. Results
CWnical k)ndings
Fie;. 1. Schematic representation of the two types of atretic cephaloceles, a = arachnoid tissue: b = bone: d = dermis: n = neuroglial loci; p = brain parenchyma: v = vessels. these vessels represent arteries or veins. The lesion dome is composed of fibrous tissue with normal hair follicles. In a Type 2 cephalocele, the meninges are intermingled with dermal fibrous tissue. Blood vessels not only exist
There were eight boys and eight girls in the study group. Fifteen patients were diagnosed after birth, either during evaluation of congenital hydrocephalus (seven cases) or directly because of a scalp lesion. The remaining patient was a baby with intrauterine hydrocephalus who was diagnosed prenatally via MR imaging. The ages of the patients at the time of consultation or hospitalization ranged from 1 day to 8 months. Six children had lesions that were painful during ordinary care, such as bathing or combing their hair. Two babies were the product of twin pregnancies. There was a family history of epilepsy in two cases and of diabetes in two others. In three additional cases there was first- or second-degree consanguinity. Two children with cerebro-oculomuscular (Walker-Warburg) syndrome had siblings with hydrocephalus and ocular anomalies that, in retrospect, we think might represent the same syndrome. The atretie cephalocele in seven patients was located in the parietal region and in nine in the occipital region. The lesions ranged in size from 10 to 35 mm and were of cystic quality on palpation. They collapsed after digital compression and seemed to refill slowly. Only
FIG. 2. Left: Photomicrograph of a specimen from the dome of a Type 1 atretic cephalocele showing atrophic squamous epithelium and the underlying rich capillary network that intermingles with fibrous hyaline tissue. H & E, x 68. Right; Photomicrograph of the stalk of a Type 2 atretic cephalocele. Note the dilated net of dysplastic vessels, foci of neuroglial elements, and clusters of meningeal cells. H & E, x 170.
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J. F. Martinez-Lage, et al.
FIG. 3. Photograph of a child with an occipital atretic cephalocele showing an alopecic lesion surrounded by a hairy collar.
three cases exhibited changes in tension with variations of intracranial pressure. The cephaloceles were invariably covered by skin, although the surface of the lesions varied. Seven children had alopecic lesions (Fig. 3) surrounded by a hairy cellar, and in eight cases there was excessive growth of hair over the cyst. Only one lesion had the appearance of a "congenital scar" of the scalp. Several cephaloceles presented with angiomatous or discolored skin, and all patients had a palpable cranial defect. The results of neurological examination were normal in eight children; the others showed some abnormality, such as decreased tone and reflexes or hyperreflexia.
TABLE 1 Neurological examination and associated anomalies in 16 patients with atretic cephalocele Case No. 1 2 3
Location of Lesion parietal parietal parietal
4 5 6 7 8
parietal parietal parietal parietal occipital
9 10 11
occipital occipital occipital
12
occipital
13
occipital
14 15 16
232
Neurological Findings normal normal hydrocephalus, hypotonic normal normal normal normal hydrocephalus, hypotonic normal hydrocephalus hydrocephalus, hypotonic hydrocephalus, hypotonic hydrocephalus, hypotonic
Type/Site of Associated Anomalies
FIG. 4. Contrast-enhanced compulerized tomography scan in a patient with Walker-Warburg syndrome. Note marked hydrocephalus, the occipital cephalocele, and the bright enhancement of the lesion.
Eight patients had macrocephaly. Table 1 summarizes the clinical details of the neurological and general examination and the associated anomalies.
Neuroradiological Investigations In all cases there was a bone defect in the area of the cephalocele demonstrated by plain skull radiographs; these were approximately 0.5 to 1.5 cm in diameter and had well-defined margins. The cranial gap was oval or elongated in shape, and the margins were on occasion partially sclerosed. The cephalocele was easily delineated by CT and in most cases had a density close to that of CSF or was slightly hyperdense in relation to brain parenchyma. Computerized tomography also showed the bone defect. In older children the edges of the cranial gap narrowed from the inside outward. In the cases studied after contrast medium infusion the lesion enhanced brightly (Fig. 4). Only four children had a completely normal brain on CT. The findings on CT and/or M R imaging are summarized in Table 2.
none none none
congenital lobar emphysema Fallot's tetralogy
TABLE 2 Computerized tomography and/or magnetic resonance imaging findings in 16 patients with atretic eephalocele
none
sacrococcygealdermal sinus none none none eyes, muscle,hands eyes, muscle
eyes, muscle, hands, heart (interventricularcommunication) occipital hydrocephalus, eyes, muscle? hypotonic occipital normal occipitaldermal sinus occipital hydrocephalus, eyes, muscle hypotonic
Finding normal atretic cephalocele triveniricularhydrocephalus dilated lateral ventricles partial agenesisof corpus callosum interhemisphericoccipitalcyst porencephalicoccipitalcyst septnm pellucidumcyst agenesisof cerebellarvermis posterior fossa cyst agyria hypodensityof white matter interhemisphericfrontal fusion anomalous draining vein
Location of Lesion Parietal 3 6 1 2 0 4 0 1 1 0 0 0 0 4
Occipital 1 9 7 1 6 0 1 0 5 6 5 5 2 5
J. Neurosurg. / Volume 77/August, 1992
Atretic c e p h a l o c e l e
FIG. 6. Magnetic resonance image of a child with a parietal atretic cephaloceledemonstrating the relationship of the lesion with the bone defect and the underlying sagittal sinus. FI(;. 5. Computerized tomography scan showing an interhemispheric occipital arachnoid cyst, a frequent finding in parietal rudimentary cephaloceles.
The presence of an interhemispheric occipital arachnoid cyst (Fig. 5) was observed in four of the seven parietal atretic cephaloceles. In several cases contrastenhanced CT scans demonstrated a large vessel within the cephalocele. Magnetic resonance imaging was performed prenatally in one case and demonstrated several cerebral anomalies that suggested a diagnosis of cerebro-oculomuscular syndrome. Five additional patients underwent MR imaging, which aided in defining the relationship of the lesion to the sagittal sinus (Fig. 6) and in delineating the intracranial anomalies.
Operative Findings Thirteen patients underwent surgical repair of the cephalocele. The parents refused surgery for two children, and one child with a flattened lesion was not offered surgical intervention. The operative procedure consisted of an elliptical incision at the base of the malformation, followed by dissection and extirpation of the sac contents. Surgical findings ranged from an apparent fibrous stalk to a cystic cavity. In 10 patients the stalk was attached to the dura or to the sagittal sinus. Three cases had cystic lesions that communicated directly with a dilated subarachnoid space. Nine children had richly vascularized lesions with numerous and engorged vessels in both the dura and the stalk. At the end of the operation, the margins of the cranial defect were rongeured and pieces of bone were placed over the dura since, in our experience, congenital bone defects do not ossify spontaneously. A ventriculoperitoneal shunt was placed in the seven children with progressive hydrocephalus. The 13 surgical specimens were submitted to histological examination. Six cases corresponded to Type 1 atretic cephalocele and seven to Type 2.
J. Neurosurg. / Volume 77/August, 1992
OlllCottle After a mean follow-up period of 5.6 years, eight children showed normal psychomotor development, two were mildly retarded, and two were severely handicapped. Four patients died; three children with cerebrooculomuscular syndrome succumbed to bronchoaspiration and one died of pulmonary embolism complicating ventriculoatrial shunting. It is important to note that five of the babies with occipital atretic cephalocele suffered from cerebro-oculomuscular (Walker-Warburg) syndrome. The best prognosis was seen in patients with a cephalocele located in the parietal region, with six of these seven children developing normally. On the contrary, an occipital location of the cephalocele indicated the worst outcome, with only two of these nine children showing normal psychomotor development. Discussion
Etiology and Pathogenesis of Atretic Cepha[oceles The etiology of cephaloceles is obscure, the majority of cases being sporadic. Nevertheless, some cases have a genetic determination and occur in families with other malformations of the CNS? A complex of cerebral, ocular, and muscular anomalies, including cephalocele in 50% of the cases, has been described as Walker-Warburg (or cerebro-oculomuseular) syndrome, an autosomic recessive disorder. 5 Experimentally, several teratogens, such as trypan blue dye, x-ray exposure, and excessive doses of vitamin A, may induce cephaloceles. 1~ In our series, four patients had a history of familial epilepsy or diabetes. In four additional cases there was a history of consanguinity or ethnic isolation, factors that are known to increase the risk of recessive traits, especially very rare ones. Regarding the development of cephaloceles, there is a controversy between those who suggest that the lesion is the result of a failure of the neural tube to close and those who support the belief that the neural tube closes normally, reopens, and then proceeds abnormally. 13
233
J. F. M a r t i n e z - L a g e , e t a l . Drapkin '~ suggested that atretic cephalocelcs constitute neural crest renmants. Based on the lngalls' work on embryos, Inoue, et al.] attributed the origin of atretic cephaloceles to the persistence of the nuchal bleb. Yokota, etal., '~' proposed that these lesions come from the involution in utero of larger encephaloceles or meningoceles. McLone and Bondareff ~' showed that the three layers of the meninges, the membranous bones of the skull, and the blood vessels originate from a multipotential primary, mesenchyme that is interposed between the closed neural tube and the superficial onelayered squamous ectoderm after the 9th day of fetal life. In our view, these abortive cephaloceles (which are frequently associated with abnormal arachnoid pouches and anomalous vessels) are formed as the consequence of an insult, either genetic or infectious, that involves this multipotential primary mesenchyme and the primitive neural tube. Incidence oJAtretic Cephaloceles Yokota, el al., ~' reported a 37.5 % incidence of atretic cephaloceles in relation to all types of cephaloceles. At our institution, 16 (50%) of 32 cases of cephaloceles were atretic. Hi~tological Features McLaurin ~~classified cephaloceles into tbur groups: 1) encephaloceles; 2) heterotopic glial rests; 3) meningoceles with central connection; and 4) meningoceles without central connection. Drapkin ~ described two varieties of rudimentary cephaloceles: Group A in which there is no bone defect underlying the malformation and which corresponds to the heterotopic glial rest group reported by McLaurin '~ and Orkin and Fisher12; and Group B which refers to those lesions that have an osseous defect and communicate with the central cavity. Schlitt, et al., H suggested that probably all these malformations contain a neuroglial component and that its detection depends on a thorough examination of the pathological specimens. The classification into our proposed Types 1 and 2 relates to the presence or absence of abnormal vasculature and neural and glial elements within the dome of the lesion. An equal number of these two types of the malformation were located in the parietal and occipital regions. These two varieties of atretic cephaloceles probably represent different stages in the development of the lesion. Vascularization of Atrelic Cephaloceles The coexistence of atretic cephalocele with anomalies of the sagittal sinus was described first by McLaurin ~~ in 1964, and again in 1983 by Inoue, et a[. 7 The latter group reported six cases studied by angiography, in which they found an anomalous upward course of the straight sinus, elongation of the vein of Galen, and splitting of the sagittal sinus around the cord of the malformation. A relationship between atretic meningocele and parietal foramina has also been documented, 934
revealing the vascular component of these cephaloceles.' In our series, the presence of anomalous vessels within the malformation was demonstrated by CT in all cases where contrast medium was administered. A pattern of primitive vascularization was also histologically proven in most cases, suggesting the persistence of fetal vessels that feed the herniated tissues. Associated Cerebral Malformations and Prognosis Parietal cephaloceles have been frequently associated with severe intracranial malformations that obscure their prognosis. ~9~5 ~7 Yokota, e t a l . , ~' reported five cases of the parietal form of cephalocele that were associated with a dorsal cyst malformation, as opposed to five occipital midline atretic cephaloceles that appeared normal on CT scans and resulted in normal development. In a recent article, Drapkin 6 described a good outcome in his three cases of rudimentary cephalocele without associated anomalies. In our experience, occipital atretic cephaloceles carry a very somber prognosis, with only two of nine children developing normally. In five of our patients, the occipital lesion was part of the Walker-Warburg syndrome. 5 The different prognosis reported by Yokota, etal., from that in our series probably depends on the racial and geographic variations described for cephaloceles in general. Di~brential Diagnosis The differential diagnosis of atretic cephalocele in our cases was established with sinus pericranii or dermoid cysts. Clinical findings of sinus pericranii include a subscalp soft tumor that empties when the patient is standing and refills when the patient is lying down. Plain skull radiographs show a thinning of the external skull table, and needle aspiration demonstrates that the mass is filled with venous blood. Sinus pericranii may be located in the parietal region at or near the midline. Dermoid cysts of the scalp and vault tend to present at the occipital midline. They are firmer than cephaloceles and may be covered by reddened skin. On plain radiographs, the shape of the bone defect of the dermoid cyst is rounded with partially sclerosed margins; in atretic cephalocele, the osseous defect is oval or elongated. On CT studies, the edges of the dermoid cyst bone defect narrow from the outside inward; the opposite is seen with atretic cephaloceles, in which the defect margins narrow from the inside outward. Scalp dermoid cysts do not enhance on CT after contrast administration, while atretic cephaloceles stain vividly. To improve the delineation of occipital cephaloceles on CT, we tilt the child's head to one side to avoid collapse of the lesion by the weight of the patient's head.
Conclusions We suggest that cases of rudimentary cephaloceles should undergo a complete neuroradiological evaluation, either by CT or MR imaging, as they may be associated with several underlying brain malformations. J. Neurosurg. / Volume 77/August, 1992
Atretic cephalocele Obviously, it is the underlying brain malformation that determines the prognosis and not the small cephalocele. In most cases, surgical repair of the lesion is advisable for many reasons: 1) cosmetic reasons; 2) to avoid the rupture or ulceration of the lesion due to its prominent situation; 3) many of these cephaloceles seem to be very painful when the baby cries or strains, probably due to the stretching of the dural component; 3 and 4) to obtain a histological diagnosis. As in other mass lesions of the cranial midline, surgical intervention should be performed by neurosurgeons to avoid injuring the venous sinuses and because the repair may require intradural exploration.
Acknowledgments The authors express their appreciation and gratitude to Mr. Saturnino Espin for photographic work and to Mrs. Mari Carmen G. Navarro and Mr. Antonio L. Alarcon for secretarial help.
References 1. Aoyagi M, Matsuhima Y, Takei H, et al: Parietal foramina complicated by meningocele. Childs Nerv Syst l: 234-237, 1985 2. Commens C, Rogers M, Klan A: Heterotropic brain tissue presenting as bald cysts with a collar of hypertrophic hair. The "hair collar" sign. Arch Dermatol 125:1253-1256, 1989 3. Curnes JT, Oakes WJ: Parietal cephaloceles: radiographic and magnetic resonance imaging evaluation. Pediatr Neurosci 14:71-76, 1988 4. DieblerC, Dulac O: Cephaloceles: clinical and neuroradiological appearance. Associated cerebral malformations. Neuroradiology 25:199-216, 1983 5. Dobyns WB, Pagon RA, Armstrong D, eta]: Diagnostic criteria for Walker-Warburg syndrome. Am J Med Genet 32:195-210, 1989
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6. Drapkin AJ: Rudimentary cephalocele or neural crest remnant? Neurosurgery 26:66%674, 1990 7. Inoue Y, Hakuba A, Fujitani K, et al: Occult cranium bifidum. Radiological and surgical findings. Neuroradiology 25:217-223, 1983 8. James CCM, Lassman LP: Spinal Dysraphisms: Spina Bifida Occulta. London: Butterworths, 1972, pp 89-97 9. Lee CM Jr, McLaurin RL: Heterotopic brain tissue as an isolated embryonic rest. d Neurosurg 12:190-195, 1955 10. McLaurin RL: Parietal cephaloceles. Neurology 14: 764-772, 1964 11. McLone DG, Bondareff W: Developmental morphology of the subarachnoid space and contiguous structures in the mouse. Am J Anat 142:273-294, 1975 12. Orkin M, Fisher I: Heterotopic brain tissue (heterotopic neural rest). Case report with review of related anomalies. Arch Dermatol 94:699-708, 1966 13. Reigel DH: Encephalocele, in Section of Pediatric Neurosurgery of the American Association of Neurological Surgeons (eds): Pediatric Neurosurgery. Surgery of the Developing Nervous System. New York: Grune & Stratton, 1982, 19p 49-60 14. Schlitt M, Williams JP, Bastian FO, et al: The small midline occipital encephalomeningocele: definition of a syndrome. Neurosurgery 24:613-616, 1989 15. Yamada H, Sakata K, Kashiki Y, et al: Peculiar congenital parieto-occipital head tumor: report of 3 cases. Childs Brain 5:426-432, 1979 16. Yokota A, Kajiwara H, Kohehi M, et al: Parietal cephalocele: clinical importance of its atretic form and associated malformations. J Neurosurg 69:545-551, 1988 17. Yokota A, Matsukado Y: Congenital midline porencephaly: a new brain malformation associated with scalp anomaly. Childs Brain 5:380-397, 1979 Manuscript received August 16, 1991. Accepted in final form January 8, 1992. Address reprint requests to: Juan F. Martinez-Lage, M.D., Regional Service of Neurosurgery, University Hospital Virgen de Arrixaca, El Palmar, E-30120 Murcia, Spain.
235
Atretic cephalocele: the tip of the iceberg JUAN F. MARTINEZoLAGE, M.D., JOAQUiN SOLA, M.D., CARLOS CASAS, M.D., MAXIMO POZA, M.D., MARIA J. ALMAGRO,M.D., AND DIEGO G. GIRONA, M.D.
Regional Service of Neurosurgery and Sections of Neuropathology and Neuropediatrics, University Hospital Virgen de Arrixaca, El Palmar, Murcia, Spain Atretic cephalocele appears as an unimportant and benign lesion. This malformation consists of meningeal and vestigial tissues (arachnoid, glial, or central nervous system rests). The authors report the findings in 16 cases (seven parietal and nine occipital) of rudimentary cephaloceles. Twelve patients presented with associated brain abnormalities detected by either computerized tomography (CT) or magnetic resonance imaging (MR). Nine lesions also exhibited an anomalous vascular component demonstrated by CT or MR imaging or at surgery. The existence of this tiny malformation in five cases was the main diagnostic clue to a severe complex of cerebral anomalies, namely cerebro-oculomuscular (Walker-Warburg) syndrome. An occipital location of the atretic cephalocele was associated with the worst prognosis, with only two children developing normally. However, a parietal location carried a better prognosis, which is contrary to the outcome reported in the current literature. The authors classify atretic cephaloceles into two types based on histological examination of the surgical specimens, and suggest that these types represent different stages in the development of this malformation. It is concluded that, in the evaluation of the atretic cephalocele, the neurosurgeon is obliged to proceed to a detailed neuroradiological study of the patient and that the prognosis does not depend on the existence of the cephalocele itself, but rather on associated "occult" brain anomalies. KEY WORDS atretic cephalocele encephalocele 9 cranial meningoeele
EPHALOCELESare congenital herniations of intracranial structures through a skull defect. ~3 In the case of cranial meningocele, the sac contains meninges and cerebrospinal fluid (CSF). If the sac also contains central nervous system (CNS) tissue, then the term "encephalocele" is used. James and Lassman ~ introduced the concept of an abortive form of meningomyelocele in 1972 with the term "meningocele manqu6," meaning spontaneous arrest in the development of that malformation. Several authors have used the expression "atretic," "abortive," "occult," and "rudimentary cephalocele," 2,6,7.16referring to a skin-covered subsealp lesion that consists of meninges and rests of glial and/or CNS tissues. The gross appearance of this malformation is that of an unimportant and benign lesion. McLaurin j~ and Yokota, et al., ~6 have stressed the high frequency of associated cerebral malformations with atretic encephaloceles. Recently, Drapkin" described a more favorable prognosis for this anomaly, distinct from the true encephalocele. We report our experience with 16 cases of this "inoffensive" congenital defect. To our knowledge, this report constitutes the largest published series of atretic cephalocele cases with a long follow-up period.
C
230
cerebro-oculomuscular syndrome 9 hydrocephalus 9 Walker-Warburg syndrome
Clinical Material and Methods
Patient Population The clinical records of 32 pediatric patients with cephaloceles who were admitted to our hospital from 1976 to October, 1991, were reviewed. Sixteen of these cases corresponded to previous descriptions of atretic cephaloeele. The clinical data were analyzed, including patient's age, sex, antenatal and family history, presentation, localization of the lesion, and the results of neurological and general examinations. Plain skull radiographs and computerized tomography (CT) scans were obtained for all patients. Contrast-enhanced CT was performed in eight children. Magnetic resonance (MR) imaging was obtained for only six patients. The surgical records were also investigated. Pathological Classification Atretic cephalocele was classified into two categories depending on the pathological features (Fig. 1). In a Type 1 cephalocele, the dural covering consists mainly of arachnoid tissue found almost exclusively at the lesion stalk and accompanied by a cluster of anomalous blood vessels (Fig. 2 left). It is difficult to ascertain if J. Neurosurg. / Volume 77/August, 1992
Atretic cephalocele at the stalk of the malformation but they extend, as a nel, toward the lesion dome. It was only in this second type that we encountered ectopic foci of neural or glial elements (Fig. 2 righl).
Follow- Up Evaluation Outcomes were determined by reviewing the outpatient records of the children or by direct-mail or telephone inquiry of their parents. Functional results were evaluated in terms of psychomotor development and neurological examination. Results
CWnical k)ndings
Fie;. 1. Schematic representation of the two types of atretic cephaloceles, a = arachnoid tissue: b = bone: d = dermis: n = neuroglial loci; p = brain parenchyma: v = vessels. these vessels represent arteries or veins. The lesion dome is composed of fibrous tissue with normal hair follicles. In a Type 2 cephalocele, the meninges are intermingled with dermal fibrous tissue. Blood vessels not only exist
There were eight boys and eight girls in the study group. Fifteen patients were diagnosed after birth, either during evaluation of congenital hydrocephalus (seven cases) or directly because of a scalp lesion. The remaining patient was a baby with intrauterine hydrocephalus who was diagnosed prenatally via MR imaging. The ages of the patients at the time of consultation or hospitalization ranged from 1 day to 8 months. Six children had lesions that were painful during ordinary care, such as bathing or combing their hair. Two babies were the product of twin pregnancies. There was a family history of epilepsy in two cases and of diabetes in two others. In three additional cases there was first- or second-degree consanguinity. Two children with cerebro-oculomuscular (Walker-Warburg) syndrome had siblings with hydrocephalus and ocular anomalies that, in retrospect, we think might represent the same syndrome. The atretie cephalocele in seven patients was located in the parietal region and in nine in the occipital region. The lesions ranged in size from 10 to 35 mm and were of cystic quality on palpation. They collapsed after digital compression and seemed to refill slowly. Only
FIG. 2. Left: Photomicrograph of a specimen from the dome of a Type 1 atretic cephalocele showing atrophic squamous epithelium and the underlying rich capillary network that intermingles with fibrous hyaline tissue. H & E, x 68. Right; Photomicrograph of the stalk of a Type 2 atretic cephalocele. Note the dilated net of dysplastic vessels, foci of neuroglial elements, and clusters of meningeal cells. H & E, x 170.
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231
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FIG. 3. Photograph of a child with an occipital atretic cephalocele showing an alopecic lesion surrounded by a hairy collar.
three cases exhibited changes in tension with variations of intracranial pressure. The cephaloceles were invariably covered by skin, although the surface of the lesions varied. Seven children had alopecic lesions (Fig. 3) surrounded by a hairy cellar, and in eight cases there was excessive growth of hair over the cyst. Only one lesion had the appearance of a "congenital scar" of the scalp. Several cephaloceles presented with angiomatous or discolored skin, and all patients had a palpable cranial defect. The results of neurological examination were normal in eight children; the others showed some abnormality, such as decreased tone and reflexes or hyperreflexia.
TABLE 1 Neurological examination and associated anomalies in 16 patients with atretic cephalocele Case No. 1 2 3
Location of Lesion parietal parietal parietal
4 5 6 7 8
parietal parietal parietal parietal occipital
9 10 11
occipital occipital occipital
12
occipital
13
occipital
14 15 16
232
Neurological Findings normal normal hydrocephalus, hypotonic normal normal normal normal hydrocephalus, hypotonic normal hydrocephalus hydrocephalus, hypotonic hydrocephalus, hypotonic hydrocephalus, hypotonic
Type/Site of Associated Anomalies
FIG. 4. Contrast-enhanced compulerized tomography scan in a patient with Walker-Warburg syndrome. Note marked hydrocephalus, the occipital cephalocele, and the bright enhancement of the lesion.
Eight patients had macrocephaly. Table 1 summarizes the clinical details of the neurological and general examination and the associated anomalies.
Neuroradiological Investigations In all cases there was a bone defect in the area of the cephalocele demonstrated by plain skull radiographs; these were approximately 0.5 to 1.5 cm in diameter and had well-defined margins. The cranial gap was oval or elongated in shape, and the margins were on occasion partially sclerosed. The cephalocele was easily delineated by CT and in most cases had a density close to that of CSF or was slightly hyperdense in relation to brain parenchyma. Computerized tomography also showed the bone defect. In older children the edges of the cranial gap narrowed from the inside outward. In the cases studied after contrast medium infusion the lesion enhanced brightly (Fig. 4). Only four children had a completely normal brain on CT. The findings on CT and/or M R imaging are summarized in Table 2.
none none none
congenital lobar emphysema Fallot's tetralogy
TABLE 2 Computerized tomography and/or magnetic resonance imaging findings in 16 patients with atretic eephalocele
none
sacrococcygealdermal sinus none none none eyes, muscle,hands eyes, muscle
eyes, muscle, hands, heart (interventricularcommunication) occipital hydrocephalus, eyes, muscle? hypotonic occipital normal occipitaldermal sinus occipital hydrocephalus, eyes, muscle hypotonic
Finding normal atretic cephalocele triveniricularhydrocephalus dilated lateral ventricles partial agenesisof corpus callosum interhemisphericoccipitalcyst porencephalicoccipitalcyst septnm pellucidumcyst agenesisof cerebellarvermis posterior fossa cyst agyria hypodensityof white matter interhemisphericfrontal fusion anomalous draining vein
Location of Lesion Parietal 3 6 1 2 0 4 0 1 1 0 0 0 0 4
Occipital 1 9 7 1 6 0 1 0 5 6 5 5 2 5
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Atretic c e p h a l o c e l e
FIG. 6. Magnetic resonance image of a child with a parietal atretic cephaloceledemonstrating the relationship of the lesion with the bone defect and the underlying sagittal sinus. FI(;. 5. Computerized tomography scan showing an interhemispheric occipital arachnoid cyst, a frequent finding in parietal rudimentary cephaloceles.
The presence of an interhemispheric occipital arachnoid cyst (Fig. 5) was observed in four of the seven parietal atretic cephaloceles. In several cases contrastenhanced CT scans demonstrated a large vessel within the cephalocele. Magnetic resonance imaging was performed prenatally in one case and demonstrated several cerebral anomalies that suggested a diagnosis of cerebro-oculomuscular syndrome. Five additional patients underwent MR imaging, which aided in defining the relationship of the lesion to the sagittal sinus (Fig. 6) and in delineating the intracranial anomalies.
Operative Findings Thirteen patients underwent surgical repair of the cephalocele. The parents refused surgery for two children, and one child with a flattened lesion was not offered surgical intervention. The operative procedure consisted of an elliptical incision at the base of the malformation, followed by dissection and extirpation of the sac contents. Surgical findings ranged from an apparent fibrous stalk to a cystic cavity. In 10 patients the stalk was attached to the dura or to the sagittal sinus. Three cases had cystic lesions that communicated directly with a dilated subarachnoid space. Nine children had richly vascularized lesions with numerous and engorged vessels in both the dura and the stalk. At the end of the operation, the margins of the cranial defect were rongeured and pieces of bone were placed over the dura since, in our experience, congenital bone defects do not ossify spontaneously. A ventriculoperitoneal shunt was placed in the seven children with progressive hydrocephalus. The 13 surgical specimens were submitted to histological examination. Six cases corresponded to Type 1 atretic cephalocele and seven to Type 2.
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OlllCottle After a mean follow-up period of 5.6 years, eight children showed normal psychomotor development, two were mildly retarded, and two were severely handicapped. Four patients died; three children with cerebrooculomuscular syndrome succumbed to bronchoaspiration and one died of pulmonary embolism complicating ventriculoatrial shunting. It is important to note that five of the babies with occipital atretic cephalocele suffered from cerebro-oculomuscular (Walker-Warburg) syndrome. The best prognosis was seen in patients with a cephalocele located in the parietal region, with six of these seven children developing normally. On the contrary, an occipital location of the cephalocele indicated the worst outcome, with only two of these nine children showing normal psychomotor development. Discussion
Etiology and Pathogenesis of Atretic Cepha[oceles The etiology of cephaloceles is obscure, the majority of cases being sporadic. Nevertheless, some cases have a genetic determination and occur in families with other malformations of the CNS? A complex of cerebral, ocular, and muscular anomalies, including cephalocele in 50% of the cases, has been described as Walker-Warburg (or cerebro-oculomuseular) syndrome, an autosomic recessive disorder. 5 Experimentally, several teratogens, such as trypan blue dye, x-ray exposure, and excessive doses of vitamin A, may induce cephaloceles. 1~ In our series, four patients had a history of familial epilepsy or diabetes. In four additional cases there was a history of consanguinity or ethnic isolation, factors that are known to increase the risk of recessive traits, especially very rare ones. Regarding the development of cephaloceles, there is a controversy between those who suggest that the lesion is the result of a failure of the neural tube to close and those who support the belief that the neural tube closes normally, reopens, and then proceeds abnormally. 13
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J. F. M a r t i n e z - L a g e , e t a l . Drapkin '~ suggested that atretic cephalocelcs constitute neural crest renmants. Based on the lngalls' work on embryos, Inoue, et al.] attributed the origin of atretic cephaloceles to the persistence of the nuchal bleb. Yokota, etal., '~' proposed that these lesions come from the involution in utero of larger encephaloceles or meningoceles. McLone and Bondareff ~' showed that the three layers of the meninges, the membranous bones of the skull, and the blood vessels originate from a multipotential primary, mesenchyme that is interposed between the closed neural tube and the superficial onelayered squamous ectoderm after the 9th day of fetal life. In our view, these abortive cephaloceles (which are frequently associated with abnormal arachnoid pouches and anomalous vessels) are formed as the consequence of an insult, either genetic or infectious, that involves this multipotential primary mesenchyme and the primitive neural tube. Incidence oJAtretic Cephaloceles Yokota, el al., ~' reported a 37.5 % incidence of atretic cephaloceles in relation to all types of cephaloceles. At our institution, 16 (50%) of 32 cases of cephaloceles were atretic. Hi~tological Features McLaurin ~~classified cephaloceles into tbur groups: 1) encephaloceles; 2) heterotopic glial rests; 3) meningoceles with central connection; and 4) meningoceles without central connection. Drapkin ~ described two varieties of rudimentary cephaloceles: Group A in which there is no bone defect underlying the malformation and which corresponds to the heterotopic glial rest group reported by McLaurin '~ and Orkin and Fisher12; and Group B which refers to those lesions that have an osseous defect and communicate with the central cavity. Schlitt, et al., H suggested that probably all these malformations contain a neuroglial component and that its detection depends on a thorough examination of the pathological specimens. The classification into our proposed Types 1 and 2 relates to the presence or absence of abnormal vasculature and neural and glial elements within the dome of the lesion. An equal number of these two types of the malformation were located in the parietal and occipital regions. These two varieties of atretic cephaloceles probably represent different stages in the development of the lesion. Vascularization of Atrelic Cephaloceles The coexistence of atretic cephalocele with anomalies of the sagittal sinus was described first by McLaurin ~~ in 1964, and again in 1983 by Inoue, et a[. 7 The latter group reported six cases studied by angiography, in which they found an anomalous upward course of the straight sinus, elongation of the vein of Galen, and splitting of the sagittal sinus around the cord of the malformation. A relationship between atretic meningocele and parietal foramina has also been documented, 934
revealing the vascular component of these cephaloceles.' In our series, the presence of anomalous vessels within the malformation was demonstrated by CT in all cases where contrast medium was administered. A pattern of primitive vascularization was also histologically proven in most cases, suggesting the persistence of fetal vessels that feed the herniated tissues. Associated Cerebral Malformations and Prognosis Parietal cephaloceles have been frequently associated with severe intracranial malformations that obscure their prognosis. ~9~5 ~7 Yokota, e t a l . , ~' reported five cases of the parietal form of cephalocele that were associated with a dorsal cyst malformation, as opposed to five occipital midline atretic cephaloceles that appeared normal on CT scans and resulted in normal development. In a recent article, Drapkin 6 described a good outcome in his three cases of rudimentary cephalocele without associated anomalies. In our experience, occipital atretic cephaloceles carry a very somber prognosis, with only two of nine children developing normally. In five of our patients, the occipital lesion was part of the Walker-Warburg syndrome. 5 The different prognosis reported by Yokota, etal., from that in our series probably depends on the racial and geographic variations described for cephaloceles in general. Di~brential Diagnosis The differential diagnosis of atretic cephalocele in our cases was established with sinus pericranii or dermoid cysts. Clinical findings of sinus pericranii include a subscalp soft tumor that empties when the patient is standing and refills when the patient is lying down. Plain skull radiographs show a thinning of the external skull table, and needle aspiration demonstrates that the mass is filled with venous blood. Sinus pericranii may be located in the parietal region at or near the midline. Dermoid cysts of the scalp and vault tend to present at the occipital midline. They are firmer than cephaloceles and may be covered by reddened skin. On plain radiographs, the shape of the bone defect of the dermoid cyst is rounded with partially sclerosed margins; in atretic cephalocele, the osseous defect is oval or elongated. On CT studies, the edges of the dermoid cyst bone defect narrow from the outside inward; the opposite is seen with atretic cephaloceles, in which the defect margins narrow from the inside outward. Scalp dermoid cysts do not enhance on CT after contrast administration, while atretic cephaloceles stain vividly. To improve the delineation of occipital cephaloceles on CT, we tilt the child's head to one side to avoid collapse of the lesion by the weight of the patient's head.
Conclusions We suggest that cases of rudimentary cephaloceles should undergo a complete neuroradiological evaluation, either by CT or MR imaging, as they may be associated with several underlying brain malformations. J. Neurosurg. / Volume 77/August, 1992
Atretic cephalocele Obviously, it is the underlying brain malformation that determines the prognosis and not the small cephalocele. In most cases, surgical repair of the lesion is advisable for many reasons: 1) cosmetic reasons; 2) to avoid the rupture or ulceration of the lesion due to its prominent situation; 3) many of these cephaloceles seem to be very painful when the baby cries or strains, probably due to the stretching of the dural component; 3 and 4) to obtain a histological diagnosis. As in other mass lesions of the cranial midline, surgical intervention should be performed by neurosurgeons to avoid injuring the venous sinuses and because the repair may require intradural exploration.
Acknowledgments The authors express their appreciation and gratitude to Mr. Saturnino Espin for photographic work and to Mrs. Mari Carmen G. Navarro and Mr. Antonio L. Alarcon for secretarial help.
References 1. Aoyagi M, Matsuhima Y, Takei H, et al: Parietal foramina complicated by meningocele. Childs Nerv Syst l: 234-237, 1985 2. Commens C, Rogers M, Klan A: Heterotropic brain tissue presenting as bald cysts with a collar of hypertrophic hair. The "hair collar" sign. Arch Dermatol 125:1253-1256, 1989 3. Curnes JT, Oakes WJ: Parietal cephaloceles: radiographic and magnetic resonance imaging evaluation. Pediatr Neurosci 14:71-76, 1988 4. DieblerC, Dulac O: Cephaloceles: clinical and neuroradiological appearance. Associated cerebral malformations. Neuroradiology 25:199-216, 1983 5. Dobyns WB, Pagon RA, Armstrong D, eta]: Diagnostic criteria for Walker-Warburg syndrome. Am J Med Genet 32:195-210, 1989
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6. Drapkin AJ: Rudimentary cephalocele or neural crest remnant? Neurosurgery 26:66%674, 1990 7. Inoue Y, Hakuba A, Fujitani K, et al: Occult cranium bifidum. Radiological and surgical findings. Neuroradiology 25:217-223, 1983 8. James CCM, Lassman LP: Spinal Dysraphisms: Spina Bifida Occulta. London: Butterworths, 1972, pp 89-97 9. Lee CM Jr, McLaurin RL: Heterotopic brain tissue as an isolated embryonic rest. d Neurosurg 12:190-195, 1955 10. McLaurin RL: Parietal cephaloceles. Neurology 14: 764-772, 1964 11. McLone DG, Bondareff W: Developmental morphology of the subarachnoid space and contiguous structures in the mouse. Am J Anat 142:273-294, 1975 12. Orkin M, Fisher I: Heterotopic brain tissue (heterotopic neural rest). Case report with review of related anomalies. Arch Dermatol 94:699-708, 1966 13. Reigel DH: Encephalocele, in Section of Pediatric Neurosurgery of the American Association of Neurological Surgeons (eds): Pediatric Neurosurgery. Surgery of the Developing Nervous System. New York: Grune & Stratton, 1982, 19p 49-60 14. Schlitt M, Williams JP, Bastian FO, et al: The small midline occipital encephalomeningocele: definition of a syndrome. Neurosurgery 24:613-616, 1989 15. Yamada H, Sakata K, Kashiki Y, et al: Peculiar congenital parieto-occipital head tumor: report of 3 cases. Childs Brain 5:426-432, 1979 16. Yokota A, Kajiwara H, Kohehi M, et al: Parietal cephalocele: clinical importance of its atretic form and associated malformations. J Neurosurg 69:545-551, 1988 17. Yokota A, Matsukado Y: Congenital midline porencephaly: a new brain malformation associated with scalp anomaly. Childs Brain 5:380-397, 1979 Manuscript received August 16, 1991. Accepted in final form January 8, 1992. Address reprint requests to: Juan F. Martinez-Lage, M.D., Regional Service of Neurosurgery, University Hospital Virgen de Arrixaca, El Palmar, E-30120 Murcia, Spain.
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