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 sur- gery. 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 W O R D S atretic cephalocele cerebro-oculomuscular syndrome encephalocele 9 cranial meningoeele 9 hydrocephalus 9 Walker-Warburg syndrome C EPHALOCELESare congenital herniations of intra- cranial 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 ~ in- troduced the concept of an abortive form of meningo- myelocele in 1972 with the term "meningocele man- qu6," meaning spontaneous arrest in the development of that malformation. Several authors have used the expression "atretic," "abortive," "occult," and "rudi- mentary 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 enceph- aloceles. Recently, Drapkin" described a more favorable prognosis for this anomaly, distinct from the true en- cephalocele. 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. 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, presen- tation, localization of the lesion, and the results of neurological and general examinations. Plain skull ra- diographs 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 230 J. Neurosurg. / Volume 77/August, 1992