|Year : 2018 | Volume
| Issue : 2 | Page : 207-213
Microsurgical management results of occipital encephalocele
Ashraf El Badry1, Azza Abdel Azeez2, Ahmed Abdel Khalek3
1 Department of Neurological Surgery, Faculty of Medicine, Mansoura University Hospital, Mansoura, Egypt
2 Department of Pathology, Faculty of Medicine, Mansoura University Hospital, Mansoura, Egypt
3 Department of Radiology, Faculty of Medicine, Mansoura University Hospital, Mansoura, Egypt
|Date of Submission||10-Jun-2017|
|Date of Acceptance||07-Aug-2017|
|Date of Web Publication||17-Aug-2018|
Dr. Ashraf El Badry
Department of Neurosurgery, Faculty of Medicine, Mansoura University Hospital, Mansoura
Source of Support: None, Conflict of Interest: None
Background Encephalocele is a central nervous system birth anomaly with a herniation of the brain and the covering meninges through a bony skull defect to the exterior.
Objective The aim of this research was to describe the prognostic factors and current possible hypotheses explaining associated anomalies observed in a series of 17 patients with encephalocele and show the effectiveness of setting up a microsurgical technique in the treatment of these cases.
Materials and methods Seventeen patients who were identified with occipital encephaloceles and referred to our Neurosurgery Clinic at the Mansoura University Hospital, Mansoura Insurance Hospital, between October 2004 and July 2013 were enrolled in this study. Patients’ sex, age at the time of the procedure, features of the lesion including site, size, associated cerebrospinal fluid leak, radiological evaluation and intraoperative findings (sac contents), and intracranial and extra cranial-associated anomalies were determined in the study.
Results In our study, 17 patients (12 female and five male) were included. Their ages varied between newborn and 1 month. The encephalocele sac was situated in the occipital region in 15 (88.2%) patients and in the occipitocervical region in two (11.8%) patients. We used a microsurgical technique on all patients. Five (29.4%) of the 17 patients died: three in the postoperative early period (0–7 days) and two in the late postoperative period (2 weeks to 3 months). The mortality rate in our study was 29.4%.
Conclusion The evidence in our series showed the importance of some factors that can alter the survival of patients with occipital encephalocele such as the sac size, the neural tissue existence in the content, hydrocephalus, infections, and other associated malformations. In this study, we report improvements in the surgical results by introducing the microsurgical technique as an alternative to traditional management despite the high morbidity and mortality linked to this congenital anomaly.
Keywords: bifidum, encephalocele, occipital
|How to cite this article:|
El Badry A, Azeez AA, Khalek AA. Microsurgical management results of occipital encephalocele. Benha Med J 2018;35:207-13
| Introduction|| |
An encephalocele is a congenital herniation of intracranial contents throughout a cranial defect. The intracranial contents, which extrude to the exterior from the defect, may incorporate cerebrospinal fluid (CSF), meningeal structures, or/and brain tissue ,. The variety of encephalocele can be expressed according to the anatomic localization of the defect . Nearly 75% of encephaloceles are situated in the occipital region, whereas 13–15% are located in the frontal ethmoidal region and 10–12% in the parietal or the sphenoidal region ,,. Occipital encephalocele occurs between the lambda and the foramen magnum, predominantly in the midline. The bony defect may be in the occipital bone or may spread out to cover the posterior lip of the foramen magnum or down to the posterior arch of the Atlas More Details; this may be better defined as ‘occipitocervical encephalocele’. Encephaloceles occur less frequently than spinal dysraphisms. The worldwide frequency of encephaloceles is not known, but has been reported to vary between 1 and 4/10 000 ,,. The encephalocele sac size is a critical prognostic factor in patient survival . The lack of brain tissues in the encephalocele sac represents a good prognostic factor . The management of encephalocele defects requires immediate surgical closure. In the microsurgical procedure, the excision or repositioning of protruded brain tissue in the sac is mandatory and the dura must be closed in a watertight manner. Generally, there is no need to surgically close the defect in the skull bone.
| Materials and methods|| |
In the Neurosurgery Clinic at the Mansoura University Hospital and the Mansoura Insurance Hospital, we monitored 17 patients (our series) with occipital encephaloceles from October 2004 to July 2013 in a prospectively study. IRB/Ethics committee approved this research and all patients wrote consent. The age of the patients varied between newborn and 1 month; 12 (70,6%) of the 17 patients were female and five (29.4%) patients were male. The sex and age of the patients were registered during clinical follow-up examinations. The localization of the sac attached to the head of the patients was verified and the size of the sac was measured carefully. We document the presence of neural tissue content inside the sac by computed tomography or MRI studies. Below, a case of encephalocele preoperative and postoperative radiology images and intraoperative pictures is shown ([Figure 1]a–[Figure 1]f).
|Figure 1 (a–f) A case of occipital encephalocele brain axial computed tomography; axial and sagittal MRI shows preoperative images, intraoperative pictures, and postoperative images. Brain computed tomography axial cuts showed a rounded central large ventricle with arrested hydrocephalous.|
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The clinical picture includes neurologic examinations, and motor deficits and all other malformations that are associated with the encephalocele were studied carefully. The patients were then subjected to a surgical intervention using a microscope. A ventriculoperitoneal shunt was applied in patients who had hydrocephalus. In addition, the postoperative status of the patients was recorded.
| Results|| |
The details of the encephaloceles, their surgical procedures, and the final condition of the patients are presented in [Table 1]. The encephalocele sac was situated in the occipital region in 15 (88.2%) of 17 patients, but in the occipitocervical region in two (11.8%) patients. The sizes of 17 sacs varied from 1×1 to 20×20 cm. The bony defect did not match with the sac size, that is, a defect can be small in a larger encephalocele. The protocol of our research included computed tomography or MRI for all patients to verify the diagnoses, determine the sac content, and to enable surgical decision making. Neural tissue was present in nine of the patients; however, it was absent in eight patients ([Figure 1]a–[Figure 1]f). All of the patients underwent microsurgical management. During surgery, the patients with occipital encephaloceles were placed in the prone position. Then, we dissected the sac from the surrounding normal skin. We then used a microscope to magnify the visualization to aid decision making in terms of whether to reposition or perform excision of neural tissue if present in the sac. This technique helps in preserving important structures associated with vital dural veins and vessels entangled in the mass. The dura mater was closed in a watertight manner. The final step was closure of the subcutaneous tissue and the skin. In patients without neural tissue in the sac, only the dura mater was sealed in a watertight manner. Subcutaneous layer and the skin was closed by surgical stitches ([Figure 1]d and [Figure 1]e). Hydrocephalus (diagnosed by progressive head enlargement, ventriculomegaly, mickymouse appearance of the frontal horn of the lateral ventricle and the third one, ballooned third ventricle, enlargement of the temporal horn of the lateral ventricle) was present in 10 patients and we applied a ventriculoperitoneal shunt for seven cases ([Figure 2]a–[Figure 2]g).
|Figure 2 (a–g) A case of occipital encephaloceles brain axial computed tomography; axial and sagittal MRI shows preoperative images, intraoperative pictures, and postoperative images. Brain computed tomography axial cuts showed hydrocephalous treated by a ventriculoperitoneal shunt.|
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We did not apply third ventriculostomy in any patients in our study. A ventriculoperitoneal shunt was not applied in three patients for the purpose of hydrocephalus arrest (one of them had a rounded central large ventricle) ([Figure 3]a–[Figure 3]e and [Figure 4]a–[Figure 4]j [Figure 3] and [Figure 4]). One patient underwent redo microsurgery because of the recurrence of the encephalocele sac. In the outpatient clinic, three patients died during the early postoperative follow-up period; two patients subsequently died within the first 3 months from the discharge date.
|Figure 3 (a–c) Axial computed tomography and MRI T2WI sagittal cuts show an encephalocele; (d, e) axial computed tomography, postoperative of the same case of an encephalocele without hydrocephalous 3 years after surgery.|
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|Figure 4 (a–g) Axial computed tomography, axial, coronal, and sagittal MRI shows a large encephalocele; (i and j) axial computed tomography, postoperative image of the same case of an encephalocele with arrested hydrocephalous.|
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Neural tissue was present in four of five patients who died. Two of them had another congenital anomaly (agenesis of the corpus callosum, lumbar meningomyelocele with associated Chiari malformation More Details). Under these circumstances, the extent of neural tissue was indicative of a poor prognosis. The size of the sacs measurements varied between 8×10 and 20×20 cm. Hydrocephalus was present in one of the five mortality cases. The mortality rate in our study was 29.4%.
The rest of the patients were receiving regular follow-up care. No correlations were found between sex, type of localization, presence of neural tissues, surgical procedure, and results in relation to age and mean diameters using the Mann–Whitney U-test. The difference between age and the size of encephalocele, sex, site, presence of neural tissues, operation, and outcomes was found to be statistically significant in relation to age and type of operation (P˂0.05). However, age and size showed no considerable difference.
In the evaluation of the surgical procedure in relation to age, we found a median age of 13.1 days in patients who underwent an encephalocele operation, whereas the median age was 6.7 days in patients group who underwent for hydrocephalus and encephalocele operation Chart 1
The patients who underwent a microsurgical procedure for encephalocele were therefore older.
The X2 test for research statistics to determine the relationship between sex and localization, sex and outcome, sex and operation, and sex and neural tissue.
The X2 test was also used to show whether there is a relationship between the site, presence of neural tissue, results, and the microsurgical procedure. Therefore, a relationship was present only between localization and operation type; that is, localization in the occipital region was observed in all patients who underwent a hydrocephalus surgery (ventriculoperitoneal shunt) and encephalocele operation (seven cases) 41.2%, otherwise (10 cases) 58.8% of patients underwent microsurgery for an encephalocele only.
Moreover, the X2 test was used to confirm whether there is any link between the neural tissue, operation type, and outcome variations. Our results indicated a statistically significant link between the previous features, that is, the outcomes of the patients depended on the presence of neural tissue, with a high likelihood of survival of patients who did not have neural tissue within the sacs.
| Discussion|| |
Encephaloceles are congenital anomalies of the central nervous system ,. They are protrusions of brain tissue. The meninges and CSF throughout a cranial defect lead to the development of a sac with variable contents. The occipital encephalocele is defined as a herniation of the meninges, one or both occipital lobes, the cerebellum, the brainstem, and/or the ventricles. The herniated neural tissue usually contains gliotic and dysplastic tissues. Some cases may have microcephaly, which makes the relocation of herniated neural tissue and sinus more difficult, with a subsequent increase in intracranial pressure because of hydrocephalus or neural tissue relocation after surgery . The underlying basis for the extrusion of brain tissue, the meninges, and CSF in encephaloceles is a primary mesodermal embryological defect . Hydrocephalus may also be present in addition to the encephaloceles. Other anomalies related to other organs and extremities can be observed in these cases ,. The severity of mental retardation is higher and the prognosis is worse in cases with more neural aberrations. In a study supported by French et al. , 17% of patients with encephaloceles had normal development, whereas severe mental retardation and physical delay were present in 83% of the patients. In our study, hydrocephalus was present in ten patients and neural tissue was found in the sac in nine patients, which may have an influence on the mentality and physical built development of these cases.
The brain tissue volume within the sac, the presence of hydrocephalus, microcephaly, and other congenital abnormalities are important factors in the prognosis of a patient with encephalocele ,. Patients with a large encephalocele are considered complicated cases because of CSF leakage or difficulty in repositioning the viable extruded brain tissue inside the cranium without increasing intracranial pressure . Surgery in such patients is usually elective, but can be performed on an emergency basis when CSF leak or sac rupture occurs ,. The surgical intervention involves excision of the hernia in general surgery by dissection of the sac through a skin incision between normal and abnormal scalp tissue with isolation of the neck, followed by setting up a microscope and then opening the sac with a careful examination of the contents. If gliotic brain tissue (nonfunctional neural tissues) is present, resection of the encephalocele sac with its content will be safe , but if viable brain tissue is present with large vessels (arteries or veins or sinuses), dissecting it from any arachnoid adhesions, then an attempt at repositioning without increasing the intracranial pressure is the best potion. Take into account tapping a ventricle to aspirate up to 25 ml. CSF (which reduce intracranial volume) if it is difficulty in reduction of the posterior fossa structures or ventriculoperitoneal shunt application may achieve the same result. Finally, excision of the protruded neural tissue part can be performed without affecting the vessels, especially veins and sinuses; otherwise, massive brain infarcture may occur. This is in agreement with Mahapatra et al. , who recommends preservation of neural tissue and vascular elements if possible, and Walia et al. , who suggested that although gliosed and ischemic herniated neural tissue can be excised (in a high percentage of cases), besides preservation of venous sinuses, above all microscopic surgery can accomplish these goals more efficient.
Frequently, the bone and dura defect was small, average 1.4 cm in diameter. When repositioning of the viable brain tissue or veins was difficult through this small defect, we enlarged the defect under a microscope for proper demarcation of important structures and avoid injury to the adjacent sagittal sinus, which can lead to hemorrhage or air embolism, occlude it by stitches with consequence of raising intracranial pressure and infarcture. This is followed by suturing of the dura in a watertight manner; as the dura is osteogenic, it will enable growth of the bone, leading to a reduction in the size of the bone defect in subsequent follow-ups. The subcutaneous and skin could then be repaired. Most of the cases did not require a cranioplasty because the defect was small and the protruded content of viable brain tissue was minor with veins that enabled successful repositioning, whereas gliotic brain tissue must be excised to facilitate repair.
In patients without neural tissue in the sac, only the dura mater was sealed and the subcutaneous and skin was repaired and closed. Hydrocephalus develops in 60% of the patients with encephalocele  perhaps because of torsion of the aqueduct of the sylvius, sinus, or aqueduct stenosis. Hydrocephalus may also occur after elimination of the encephalocele because of changes in the CSF circulation dynamics or obstruction of the sagittal sinus. This may occur during closure of the encephalocele. For the same reason, intracranial vessels may pass into the sac and loop in to supply normal brain parenchyma; excision of extruded brain tissue in such cases can produce infarctions ,. An aventriculoperitoneal shunt is applied in encephalocele patients with hydrocephalus or a third ventriculostomy is an alternative option ,. Among our series of patients, hydrocephalus was confirmed in 10 (58.8%) of 17 patients and a ventriculoperitoneal shunt was performed in seven patients. A shunt was not performed for three patients because of hydrocephalus became compensated and defined as arrested hydrocephalus. According to the literature, the mortality rate is nearly 33.3% in patients with encephaloceles in some papers , which is slightly lower than that in our series of cases (mortality rate 29.4%); this is in agreement with the results of Kiymaz et al. , but they reported appropriate antibiotic administration but and we assumed our good results due to microscopic technique application (corner stone in our study), presence of other congenital anomalies limited number and small group of patients beside a good antibiotic management administration. Hydrocephalus and infection represent the most common complications that occur in the postoperative period . Infections may result in more complications and could increase the rates of morbidity and mortality. However, signs of infection were found in three patients during the postoperative period and they were treated with an appropriate broad-spectrum antibiotic, that is for 2–3 weeks, which is the major reason why our mortality rate [in two cases (11.8%)] is in agreement with the rates reported in the literature.
During the course of follow-up of the cases in the outpatient clinic, five patients died postoperatively, three patients died during the early postoperative period, and two patients died within the first 3 months after discharge. Neural tissue was present in four (80%) of the five patients who died. The size of the sac was not measured in one of the five patients, but in the remaining five, it was large to very large. Hydrocephalus was present in one (20%) of the five patients who died because of this reason. Hydrocephalus was not associated with a poor prognosis. The large size of the sac and neural tissues are factors that lead to an increase in the mortality rate.
Our studies showed that the sac size, the neural tissue content, infection, and other malformations that may be associated with an encephalocele are factors that may alter the prognosis. Nevertheless, an occipital encephalocele is a congenital neurosurgical pathology with high morbidity and mortality rates, even though appropriate treatments are applied during the preoperative and postoperative period.We assume that the use of a microscope in dealing with these cases may improve the outcome. With better visualization of the nervous structures and better assessment of normality of these tissues (excision or repositioning), vessels, especially those that return from the extruded brain toward the cranium and sinuses present on the edges of the dural defect, must be handled with care in dural closure (avoid venous infarcture). Most studies (that is not common) did not report the microsurgical technique, but we cannot perform a comparison because of the small number of our patients and the presence of other factors that affect survival such as other congenital anomalies, etc.
The pathogenesis is believed to be a combination of diminished skull base growth and normal growth of posterior fossa structures . It is possible that a similar dysembryogenic process in other parts of the neural tube leads to the presence of coexisting anomalies. The most widely accepted theory of the formation of encephalocele posits that neuroschisis occurs after neural tube closure , and it occurs as a postneurulation phenomenon ,,,. It is important to consider encephalocele as more than just a skull defect with herniating brain tissue.
| Conclusion|| |
The evidence in our series indicated the importance of some factors that can alter the survival of patients with occipital encephalocele such as the sac size, the presence of neural tissue in the content, hydrocephalus, infections, and other associated malformations. In this study, we report an improvement in the surgical results by introducing a microsurgical technique as an alternative to traditional management despite the high morbidity and mortality linked to this congenital anomaly.
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Conflicts of interest
There are no conflicts of interest.
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