The pathology of occipital encephalocoele and a discussion of the pathogenesis

A giant occipital encephalocele with spontaneous hemorrhage into the sac: A rare case report

In giant encephalocele, head size is smaller than the encelphalocele. Occipital encephalocele is the commonest of all encephalocele. In our case, there was rare association with giant encephalocele with old hemorrhage in the sac. This was a unique presentation. In world literature, there was rare association with giant encephalocele with hemorrhage.

[The ultrasonographic diagnosis of fetal encephalocele at 13th gestational week]

BACKGROUND

Encephalocele presents a rare anomaly of central nervous system, developed as a consequence of neural tube closing defect during early embrional development, and it is described by a baggy formation which prolaborates through the pores of the scull, filled with brain tissue, cerebrospinal liquor and entwined with meninges. According to literature search, until this day, the earliest it can be ultrasonically detected is the 13th gestation week, with the appliance of three-dimensional ultrasound.

CASE REPORT

We presented 25 years old patient, ultrasonically diagnosed with occipital fetal encephalocela at the 13th gestation week. A gestation sack was located in the right uteral corn of the two-corned uterus with one cervix. The diagnosis was confirmed also by trippled value of alpha-fetoprotein in maternal serum: 75.98 IU/mL.

CONCLUSION

Ultrasonic examination is the method of choice for prenatal detection of a fetal anomaly. It is possible to diagnose encephalocele if it prominates above the limits of the scull.

Management of hydrocephalus associated with occipital encephalocoele using endoscopic third ventriculostomy: report of two cases

BACKGROUND

Occipital encephalocoele is the most common cranial dysraphism in the western hemisphere and is often complicated by hydrocephalus. Management of hydrocephalus and reducing the CSF pressure is crucial in preventing dehiscence at the site of the encephalocoele repair.

METHODS

Two female patients had presented with occipital encephalocoeles. The first patient (aged 42 days) had undergone repair of the occipital encephalocoele and then developed hydrocephalus with recurrence of the encephalocoele. The second patient (aged 12 months) had hydrocephalus associated with an occipital encephalocoele at initial presentation.Both the patients underwent endoscopic third ventriculostomy (ETV) through a right frontal burr hole. In the first patient, ETV was performed after shunt dysfunction at the age of 9 months. Because she presented with recurrence of the encephalocoele 15 months later, a repeat endoscopic third ventriculostomy was performed. She required a ventriculoperitoneal shunt during the same admission because of the early failure of the ventriculostomy. In the second patient, it was performed before the encephalocoele repair, both ETV and the repair being conducted under the same anesthesia. ETV was performed using a rigid scope and the perforation in the third ventricular floor was enlarged using a No. 4 Fogarty catheter.

RESULTS

The first patient had no recurrence of encephalocoele at follow-up of 10 months but she presented with recurrence of the occipital encephalocoele after 15 months. The second patient had no evidence of recurrence at follow-up after 16 months. The lateral and third ventricular volumes had decreased in both the patients at initial follow-up.

CONCLUSION

ETV can be an effective treatment option for encephalocoele-associated hydrocephalus, even in children under the age of 1 year. It may obviate the need for placement of CSF shunts that have a risk of infection and dysfunction. However, delayed failure of ETV may occur as seen in our first patient, indicating the need for careful and long-term follow-up.

Occipital encephalocele and MURCS association: case report and review of central nervous system anomalies in MURCS patients

The combination of MURCS association (Müllerian duct and renal agenesis, upper limb and rib anomalies) and occipital encephalocele occurred in a stillborn girl of 41 weeks gestation. The malformations are compatible with a defect in the organization of the paraxial mesoderm that gives rise to occipital, cervical, and thoracic somites and adjoining intermediate mesoderm. These structures contribute to the occipital bone, cervical spine, upper limbs, and urogenital system. Brain imaging may be useful in assessing MURCS patients, if cranial malformations prove to be clinically important in these individuals.

Uncommon posterior cranial fossa anomalies: MRI with clinical correlation

The clinical and MRI findings in two cases of rhombencephalosynapsis (RS) and two of tectocerebellar dysraphia (TCD) with an associated occipital encephalocele were studied to elucidate the clinical picture and embryogenesis of these rare anomalies. To our knowledge, only one case of TCD [1] and four of RS [2, 3] examined by MRI during life have been reported. The clinical picture in the cases of RS was rather constant and there were similarities with TCD. Consideration of the embryogenesis of the neural tube suggests a temporal proximity of the abnormalities, with TCD arising at a slightly earlier time.

Ventricular volume reduction technique--a new surgical concept for the intracranial transposition of encephalocele

The authors propose a new operative technique for the intracranial transposition of an encephalocele by using the associated hydrocephalic state. In the first stage, the intracranial pressure buffering effect of the encephalocele sac is reduced by the closing of the dural defect. The repaired dural defect allows intraventricular pulse pressure to produce ventriculomegaly. In the second stage or in infants with hydrocephalus, the extracranially herniated brain is transposed into the intracranial cavity during ventricular shunting with appropriate drainage of cerebrospinal fluid.

A ten-year review of encephalocele in a teaching hospital

A 10-year review of infants with encephalocele was carried out in a multicentered teaching hospital. Out of 23,438 infants seen within the period, only 12 cases of encephalocele were seen, giving an incidence of 0.5/1000 births. Nine (75%) of patients had occipital encephalocele, two (16.7%) occipitoparietal and one (8.3%) fronto-nasal. Two patients had spina bifida as an associated neural tube defect while ocular abnormalities were seen in another two. None had neurological defects at birth but some showed evidence of hydrocephalus and delayed milestones after surgery. Ultrasonic diagnosis was made in one case only. The etiologic, prognostic and descriptive characteristics, in addition to obstetric management of encephalocele are discussed.

Meningoceles, meningomyeloceles, and encephaloceles: a neuro-dermatopathologic study of 132 cases

Because there have been few comprehensive histopathologic studies of meningomyeloceles and related malformations, we undertook a systematic study of these lesions. One hundred and thirty two cases were obtained from our surgical pathology files; these included 38 meningoceles, 71 meningomyeloceles, and 23 encephaloceles. Tissue sections were stained with hematoxylin and eosin; special stains included trichrome, alcian blue, Fontana-Masson, Nissl, Holzer, and immunoperoxidase for glial fibrillary acidic protein. Epithelial changes included ulceration, atrophy, or nevoid hyperplasia of the epidermis, and loss of appendages. Mesodermal features included fibrous zones resembling dura, subarachnoid tissue or scar (99% of cases), increased numbers of blood vessels (83%), hypertrophy of arrector pili muscle (42%), lipoma formation (38%), and immature skeletal muscle fibers (5%) that rarely intermingled with neuropil-like matrix. The latter tissue was identified in 71% of cases and included neurons, astrocytes, oligodendroglia, and ependyma. Forty-eight percent of cases included peripheral nerve fibers or roots, and some fibers formed onion bulb or Pacinian corpuscle-like structures. Meningothelial cells were observed in 26% of cases and sometimes formed recognizable whorls. Choroid plexus was noted in 3 cases, one example showing an unusual dystrophic calcification that formed long parallel spicules. Pigmented dendritic cells were observed within zones of fibrous tissue in 10% of cases. These malformations involve complex arrangements of cutaneous, neuroectodermal, and mesodermal elements. Because they may be encountered by dermatopathologists, familiarity with the microscopic features of dysraphic lesions is essential.

Morphological evaluation for neuronal maturation in anencephaly and encephalocele in human neonates. A proposal of reclassification of cephalic dysraphism

The developmental pathogenesis of cranium bifidum and exencephaly, as well as other forms of the dysraphic state, remains unresolved. The process of neuronal maturation under such conditions is the major definitive factor for functional prognosis and may be the key to the embryopathogenesis. The neuronal maturation processes in cranium bifidum and anencephaly were analyzed in both human neonatal autopsy and surgical specimens, utilizing the technique of immunohistochemical morphological analysis. The results suggest that anencephaly is a form of neuroschisis, a defect in which the neuronal developmental process arrests and results in dys- or rather aplastic cortical architecture. In contrast, although the cortical architecture is often distorted, neuronal maturation in cases of cranium bifidum cysticum is primarily complete, demonstrating normal cerebral cortical layers and NSE positive neural elements. In conclusion, it is strongly suggested that anencephaly is the most severe form of cranium bifidum, as is myeloschisis in spina bifida, without supportable neuronal maturation. Recognizing these points in the developmental stages with regard to the degree of neuronal maturation, a reclassification of cephalic dysraphism is proposed. The embryopathogenetic and epidemiologic aspects of this proposal of reclassification are discussed.

Cranium bifidum in northern Nigeria

At the Ahmadu Bello University Hospitals in northern Nigeria, 35 girls and 29 boys with cranium bifidum were registered between 1971 and 1985. Only 25% of the patients were brought to the hospital within 24 h of life; 57 had been delivered at home without the mothers having received formal prenatal care. The majority (69%) of the lesions occurred in the occipital region; 52 (81%) were encephaloceles while the others were cranial meningoceles. Resection and repair were performed in 35 patients by general surgeons who had no facilities for vertriculoperitoneal shunts in infants with hydrocephalus. Thirteen children died in the hospital, 3 moved away, and 34 were lost to follow-up at 1 month. Only 3 were seen up to 1 year. Improvement in the care of such patients is expected since a neurosurgical unit has now been established.

Subtorcular occipital encephaloceles. Anatomical considerations relevant to operative management

Three cases of occipital encephalocele, one with associated myelomeningocele, are presented. All received preoperative evaluation with magnetic resonance imaging. Such studies provide optimal demonstration of the cerebral and hindbrain anatomy to guide operative treatment and formulate prognosis. Review of available radiographic, operative, and pathological information suggests that most, if not all, occipital encephaloceles are associated with an anomaly of the hindbrain, and the usual anomaly is a rhombic roof encephalocele. In such cases, the site of cranial herniation is caudal to the torcula, regardless of the presence or absence of occipital lobe tissue within the sac. Experimental and clinical analysis suggests that occipital encephaloceles most likely arise from abnormalities in the development of the skull base.

Central nervous system malformations induced by triamcinolone acetonide in nonhuman primates: pathology

Triamcinolone acetonide (TAC) was administered to pregnant macaques (Macaca mulatta [15] and M. radiata [7]) during gestational days (GD) 23 to 41 using various dosing schedules. A daily dose of 10 mg/kg is approximately equal to 100 x the human dose equivalent. The brains of the fetuses and infants were studied grossly and histologically. All cases displayed either the mild form of the TAC-induced syndrome (craniofacial dysmorphia, cranium bifidum occultum, meningocele, and mild distortion of the midbrain) or the more severe form (occipital encephalocele, hydrocephalus, severe distortion of the midbrain or midbrain "beaking," shunting of cerebrospinal fluid, and craniofacial malformations). The dysmorphology was dose-related, with severity increasing at higher doses or with increased numbers of treatments. Individual cases were assessed for the severity of the syndrome by comparison of like components between groups. The lesions observed were morphologically comparable to those described in spontaneous human cases; the TAC-induced occipital encephaloceles were associated with brainstem and cerebellar abnormalities, and, with the less severe form of the syndrome, brainstem abnormalities were occasionally present, with occipital meningoceles. Controversy exists concerning the significance and temporal development of the midbrain changes. However, the associated alteration in aqueduct conformation may have been responsible for functional compromise and ensuing hydrocephalus.

Central nervous system malformations induced by triamcinolone acetonide in nonhuman primates: pathogenesis

The pathogenetic sequence for TAC-induced encephalocele is in agreement with hypotheses proposing that neural tube closure is followed by protrusion of the mesencephalon, with subsequent growth and development resulting in herniation of the cerebrum and cerebellum. This model could serve to clarify the pathogenesis of encephalocele and to stimulate further study in comparing this defect to other dysraphic states. Triamcinolone acetonide (TAC) was administered intramuscularly (10 mg/kg) to 16 pregnant rhesus monkeys (Macaca mulatta) for 5 alternate days of pregnancy, beginning on gestational day (GD) 23. Conceptuses were removed by hysterotomy at GD 35, 42, 50, or 70 and examined grossly and histologically. Length, area, and perimeter of the tectum and aqueduct area and perimeter were measured with an image analyzer. Changes in treated specimens were suggestive of forces within or ventral to the tectum resulting in dorsal protrusion, rostral-posterior stretching, and attenuation. The angle of the cephalic, pontine, and cervical flexures was also measured. The more acute angle of the cephalic flexure and less acute cervical flexure of treated specimens could represent altered orientation secondary to a mesenchymal deficiency. However, the less acute angle of the pontine flexure in treated specimens suggests an intrinsic alteration in the neural tube. This suggests that encephalocele may result from a combination of mesenchymal and neural tube abnormalities.

A new syndrome with features of the Smith-Lemli-Opitz and Meckel-Gruber syndromes in a sibship with cerebellar defects

The Smith-Lemli-Opitz syndrome (SLOS) and the Meckel syndrome (MS) have been regarded as separate autosomal recessive entities. Recently, overlap of these two syndromes has been discussed. A sibship containing a probable new syndrome with features reminiscent of the SLOS and the MS is presented. The literature is reviewed with regard to the frequency of various malformations in these syndromes. Clinical manifestations and cerebellar abnormalities in these sibs are similar to those described in the Joubert syndrome (JS). These three cases may represent a new syndrome with features in common with SLOS, MS, and JS resulting from the same mutant gene, which exhibits considerable pleiotropy.

Fourth ventriculoceles with extracranial extension

The radiographic features and long-term clinical outcome in three patients who presented at birth with a cystic suboccipital mass in direct communication with the fourth ventricle are reviewed. The pathological findings in a fourth infant who died are also discussed. All surviving infants were treated with cyst excision and diversion of cerebrospinal fluid. The prognosis in these children, followed from 6 to 20 years, surpasses that of the more common occipital encephalocele, for which this entity could be mistaken. The morphogenetic implications relative to more common congenital lesions in this location are discussed.