Introduction
An encephalocele is defined as the herniation of intracranial content through a bony defect in the skull (bifid cranium). This condition is part of the disorders involving the fusion of midline structures of the primitive neural tube during the first 3 weeks of gestation1,2, where central nervous system malformations make up approximately one-third of all congenital malformations in the perinatal period2.
In encephalocele, there can be a herniation of meninges (meningocele), meninges and a portion of the brain (meningoencephalocele), or even a combination of meninges, a portion of the brain, and a portion of the ventricular system (meningohydroencephalocele)1. One-third of central nervous system malformations are diagnosed during the prenatal period, with encephalocele having an incidence of approximately 1 case/5000-10,000 live births, with a predominance in females3,4.
The etiology is of multifactorial origin, including genetic factors, environmental factors, the use of anticonvulsants such as valproic acid and carbamazepine, maternal diabetes, and folic acid deficiency during gestation5. Encephalocele is classified according to its location: occipital, parietal, and sincipital (nasofrontal, nasoethmoidal, and nasoorbital) (Table 1), with approximately 75% being located in the occipital region and typically containing cerebrospinal fluid, mostly with cystic content; less frequently, it may contain neural tissue6.
Tabla 1. Classification of encephalocele according to its location
| Classification of encephalocele |
|---|
| Frontal/sincipital (nasofrontal, nasoethmoidal y nasoorbital) |
| Parietal |
| Occipital |
Likewise, encephalocele is commonly clinically associated with visual manifestations, seizures, intellectual delay, malformations, and chromosomal abnormalities, such as in the case of trisomy 13, trisomy 18, and trisomy 206,7.
Here, we present the case of a male newborn at 35 weeks of gestation, referred with a diagnosis of prematurity, frontal encephalocele, atrial septal defect, with a diagnosis of cleft lip and hyperbilirubinemia. The case was surgically addressed and managed with a timely approach, allowing for optimal resolution.
Clinical case
Male newborn, premature at 35 weeks of gestation, referred to the Children’s Hospital of Puebla in the state of Puebla, at 4 days of age, with diagnoses of prematurity, frontal encephalocele, atrial septal defect, cleft lip, and hyperbilirubinemia.
Mother, 25 years old, without substance abuse issues, apparently healthy. Father, 24 years old, with a history of occasional alcoholism and 1 year of marijuana and cocaine use. Two apparently healthy siblings.
They mention that during prenatal check-ups, at the 28-week gestation ultrasound examination, a cranial malformation and a loss of continuity in the frontal region were reported, with herniation of meninges and the formation of two communicating sacs with anechoic content.
On physical examination, there is a noticeable mass in the frontal region between the orbits and the upper left part of the nose, with apparently intact skin, approximately 15 cm in size, and a soft consistency. The right eye appears to be developing normally, and there is a unilateral left cleft lip and palate (Fig. 1).
Figure 1. Pre-operative imaging of frontoethmoidal encephalocele.
After birth, due to the condition presented and exposed in the images in figure 1, a cranial tomography was requested, in which a solution of continuity of fronto-ethmoidal location was observed, with a defect of liquid density associated with diathesis and hypoplasia of the frontal and ethmoid bones, as well as dimorphism of the sphenoid and maxillary cavity and absence of both the ethmoid bone and the palatine bone (Fig. 2).
Figure 2. A: coronal reconstruction, B: sagital reconstruction, and C: axial section. Computed tomography scan showed a large encephalocele through a frontoethmoidal bone defect, consisting of most of the left brain.
Hypoplastic left orbit with the apparent absence of eyeball seen in 3D reconstruction (Fig. 3).
Figure 3. Tomography with 3D reconstruction in A: axial, B: sagittal, and C: coronal slices.
Based on imaging studies, it was decided to intervene by the pediatric neurosurgery department performing a surgical approach for drainage and reconstruction of fronto-nasal ethmoidal encephalocele with favorable evolution.
Adequate post-operative hospital control was performed, addressing the conditions adjacent to the main condition.
Discussion
Neural tube defects (NTDs) are congenital malformations produced by the lack of fusion during the embryonic stage between the 3rd and 4th week of gestation, in which the nervous tissue is exposed to the outside. These can be cranial (encephalocele and anencephaly) and spinal (spina bifida).
Among the NTDs, spina bifida is considered the most frequent, followed by anencephaly and encephalocele, the latter being the least frequent defect with an incidence of 1/5000 cases6 caused by structural defects of the skull, which leads to herniation of the brain tissue, causing neurological deficit determined by the level of the lesion and the degree of neural tissue involvement6.
The classification of encephalocele is based on the location of the defect: Parietal, sincipital, and occipital, the latter being the most frequent in 80% of cases6,7 and few cases reported, in the sincipital8 location as previously described in the case presentation.
In the sincipital defects, the lesions occur at the level of the junction of the face and forehead. They usually have alterations in the brain, such as disorders of the olfaction, optic nerves, hypothalamus, midbrain, and temporal lobes.
At this level, they are again subdivided into nasofrontal in which the defect is located in the bregmatic region, between the frontal and nasal bones; nasoethmoidal in which the defect is located in the cribriform plate or in the ethmoid, and at the nasal basal level in which it occurs within the ethmoid and sphenoid bones.
The diagnosis of encephalocele can be made from early gestational age, as long as there is adequate pre-natal control.
Secondary to calcification of the skull beginning at 10 weeks of gestation, diagnosis is usually not possible before that time. However, diagnostic reports were used at 13 weeks of gestation, through transvaginal transducers.
Ultrasonography represents a very useful tool that allows the study of its evolution, as well as the postpartum therapeutic options, showing the presence of bone defects.
Cabinet studies usually show anechoic images in case of presenting liquid content or dense if there is an encephalic mass inside the brain as described in our case.
In the absence of prenatal ultrasound, the diagnosis is clinical during the physical examination of the newborn, supported by complementary studies such as skull radiography, computed axial tomography, or nuclear magnetic resonance9. However, in our case, due to the parent’s history it was not possible to associate any triggering factor for this pathology, so genetic studies were suggested, but the results were not conclusive since the parents did not attend the follow-up.
Depending on the size of the volume of the herniated brain tissue, different clinical manifestations are associated, that is, in larger encephalocele there may be blindness, mental delay, paralysis, or areflexia, however, in our case, we reported data of paralysis and areflexia9.
There are other associated anomalies such as schizencephaly, microgyria, agenesis of the corpus callosum, Chiari type II malformations, and hydrocephalus9, the last being positive in our patient.
Mortality of affected children is higher during the 1st day of life and may persist in infancy where other predictions such as lesion size, location, crain content, and other added conditions are added.
Encephaloceles of frontal or parietal location are characterized by a fairly favorable prognosis, with a high probability of an increase in mental development after surgery.
The treatment of encephalocele is surgical and requires an early and multidisciplinary approach, performed in tertiary-level hospitals, in our patient drainage was performed with the reconstruction of the bone defect, which conditions a favorable response.
Given the low percentage of cases of sincipital encephalocele reported in the literature, the successful reporting of this case is important for our institution since it is the first case registered in our institutional database.
Conclusion
Sincipital encephalocele is an extremely uncommon NTD presentation, however, it must be considered during prenatal anomalies screening. Folic acid administration during the prenatal period must be ensured to prevent any kind of NTDs.
Acknowledgments
The authors appreciate the participation of the parents and physicians involved in the writing of the case.
Funding
The authors declare that they have not received funding.
Conflicts of interest
The authors declare no conflicts of interest.
Ethical considerations
Protection of human and animal subjects. The authors declare that no experiments were performed on humans or animals for this study.
Confidentiality, informed consent, and ethical approval. The authors have followed their institution’s confidentiality protocols, obtained informed consent from the patient’s parents and received approval from the Ethics Committee. The SAGER guidelines were followed according to the nature of the study.
Declaration on the use of artificial intelligence. The authors declare that they have not used any type of generative artificial intelligence for the writing of this manuscript.
