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: Encephalocoeles are relatively rare congenital abnormalities. There have been a few classifications of encepahlocoeles but these are predominantly anatomical. A more clinical classification system would assist in planning treatment, surgical procedures and assessing outcomes.
Materials and Methods
: All encephalocoeles presenting at the Craniofacial Unit at Inkosi Albert Luthuli Central Hospital were reviewed. There were 207 patients with 224 encepahlocoeles. The clinical presentation and CT findings were analysed and used to group these encephalocoeles.
: There were 5 distinct groups with some having subgroups. 1. Cranial (n = 43). These were located on the calvarium and was subdivided into subgroups according to the anatomical location. These were occipital, parietal, frontal, temporal and acrania. 2. Nasal (n = 122). These presented in the nasal region and had 2 large subgroups (supranasal and infranasal) depending if the pathway and defect was above or below the nasal bones. 3. Orbital (n = 21). These presented with displacement of the globe and had 2 subgroups termed anterior and posterior. Basal (n = 11). The pathway of these encephalocoeles were via the floor of the anterior cranial fossa often with no visible deformity of the face. 5. Cleft related (n = 27). The pathway of these encephalocoeles were via an existing craniofacial cleft.
: This classification system demonstrated good clinicopathological correlation. This allowed one to better appreciate the pathway and assess concomitant deformities. It also directed one to plan the procedure and to detail the surgical corrections required to produce satisfactory outcomes.
An encephalocoele is a relatively rare congenital abnormality with herniation of the brain and meninges outside of the cranial cavity. The incidence varies greatly and seems to have racial and geographical predeliction. It is more common in the Asian and African race and relatively rare in the Caucasian group. The reported incidence is between 0.8-3.0 per 10 000 live births.
It may be an isolated finding but more often than not there are other associated abnormalities. These anomalies may be in the central nervous system, face, limbs, cardiac, abdominal or genitourinary systems.
Encephalocoeles can have a range of clinical presentations and can very form a small lump to grotesque craniofacial deformities. In order to understand encephalocoeles and help in communication, classification systems have been proposed. The most popular classification is that of Suwanela and Suwanela which was reported in 1972.
This was based on 12 cases of encephalocoeles which were all post mortem cases. These were all sincipital encephalocoeles. They classified it into 5 broad groups with 17 possible subgroups. The 5 groups were occipital, cranial vault, frontoethmoidal, basal and cranioschisis. At that time period the ability to image encephalocoeles were rudimentary compared to CT and MRI scans that are available now. Isotope cisternography, ventriculography and air studies were some of the methods used to delineate encephalocoeles.
These were obviously not very accurate in detailing the pathway and defining the soft tissue and bone abnormalities. The shortcomings of this classification are multiple. Firstly and probably the most significant is there is little or no clinicopathological correlation to categorize the appearance according to the type of encephalocoele. Secondly there are some anatomical inaccuracies. One of the frontoethmoidal subgroups are referred to as ‘naso-orbital’. In such cases the nasal bones are not involved and the nose may be completely normal. Since they had 12 cases and enumerated 17 possible types of encephalocoeles, some of the ones described were regarded as ‘theoretical’ encephalocoeles. These have now been repeatedly described in the literature. The final limitation of the classification is that it does not take into account newer types of encephalocoeles that have since been described.
The Australian Craniofacial Unit has proposed a classification based on their experience.
The second paper is based on 23 patients with frontoethmoidal encephalomeningoceles and they termed it the FEEM classification. The acronyms represented the facial deformity, external bone defect, exit pathway and malformation of the brain.
Because of its rarity, most reports on encephalocoeles consist of a small number of patients. A large series of 400 cases has been reported by Arifin (Indonesia), 133 by Mahapatra (India) and 108 by Mahatumarat (Thailand) which were all mainly frontoethmoidal ones.
Most of these studies focused on the the surgical outcomes rather than analysis of the subtype of the encephalocoele. The large series of Arifin found that 87% of the cases were of the nasoethmoidal type with or without a nasoorbital component.
Mahatumarat proposed a modification of the Suwanela classification and had 5 groups which were nasofrontal, nasoethmoidal, naso-orbital, combined and abortive.
We would like to report on our experience of 207 patients with 224 encephalocoeles seen in our craniofacial unit. We would like to propose a new classification of encephalocoeles which has clinicopathological correlation, takes into account newer described encephalocoeles, has simple and less confusing terminology and will allow better communication amongst craniofacial surgeons.
Materials and Methods
The charts of the Craniofacial Unit at Inkosi Albert Luthuli Central Hospital were reviewed and these included patients first seen at other hospitals (Grey's and Wentworth) where the unit was previously based. All patients seen at the craniofacial clinic with a diagnosis of encephalocoeles had their charts reviewed. All patients with CT scan evidence of herniation of brain and meninges outside the cranial cavity were included. Exclusion criteria were those patients who did not have CT imaging performed or those with no evidence of an encephalocoele on review of the CT scan. It must be noted that some patients with especially occipital encephalocoeles did not present to the craniofacial clinic but were treated in the neurosurgery clinic. There were 207 patients with 224 encephalocoeles. There were 98 males and 109 females. The predominant race group was the Black population. The ages ranged from 1 day to 6 months. All patients had a CT scan. A nomenclature system was devised whereby the clinical presentation, features and CT scan findings allowed us to categorise these patients into groups. Some of these patients had leaking encephalocoeles and these were operated on urgently. Those patients who had tenous skin cover and imminent CSF leak were also operated on an urgent basis. The other patients were operated on an elective basis at around 3 months of age. Depending on the findings, different surgical approaches and strategies were used to excise the encephalocoele and reconstruct the craniofacial skeleton. The aims of the surgery was to excise the encephalocoele, achieve watertight dural closure, bone grafting the defect, correction of craniofacial abnormalities, obviating or minimizing any visible scars and correction of soft tissue deformities such as canthoplasty.
There were 224 encephalocoeles in 207 patients. These encephalocoeles were categorized into groups and subgroups (Table 1). Based on this the proposed classification has 5 broad groups – cranial, nasal, orbital, basal and cleft related.
Table 1Groups, subgroups and number of encephalocoeles.
This group were encephalocoeles which presented on the cranium and these were named according to the anatomical site. There were 43 patients in this group. The most common ones were the occipital (15) and frontal (15).
These presented as a single lump or one with multiple lobes. They were usually in the midline. The size varied from small to ones that almost mirrored the size of the cranium and sometimes larger.
These were commonly on one side rather than midline.
These presented between the frontal bones or on one side.
These were usually unilateral presenting as a mass.
There were a few cases where there was near total absence of the cranial vault bones. These patients usually had severe brain deformities.
Fig 1 demonstrates preoperative views of an encephalocoele in the parieto-occipital region.
These were all encephalocoeles which presented in the nasal region. This was the most common group and comprised 122 patients. There were 3 groups that we identified that had distinct clinical features that correlated with the tract and pathway of the encephalocoele.
After exiting from the base of the anterior cranial fossa, this encephalocoele exited from the face above the nasal bones. The presentation was usually that of a symmetrical midline mass whose maximal diameter was above the medial canthus. There was no assosciated telecanthus. The nasal bones were displaced in an inferior and posterior direction. There were 68 patients in this group. b. Infranasal:
This encephalocoele exited from the face below the nasal bones. This usually presented as a bilateral asymmetrical lump whose maximal diameter was below the medial canthus. Telecanthus was common and there was medial canthus displacement. The nasal bones were displaced in a superior and anterior direction. There were 53 patients in this group.
Fig 2a, b shows the typical clinical presentation of a supranasal and infranasal encephalocoele. Fig 3 a, b demonstrates the difference in nasal bone displacement with the supranasal and infranasal groups. c. Intranasal:
This is the least common nasal group (n=1) and the encephalocoele presents as a mass behind the nasal bones causing it to balloon out.
After exiting the anterior cranial fossa these encephalocoeles exit into the orbit. There are 2 distinct groups that are seen.
These encephalocoeles usually exit between the lacrimal and nasal bones. They present as a mass in the medial canthal region and usually displace the globe laterally and superiorly. There may be displacement of the medial canthus. There were 15 patients in this group.4 of these patients had bilateral encephlocoeles giving a total of 19 encephalocoeles. Fig 4 demonstrates the presentation of an anterior orbital encephlocoele and the CT images.
These encephalocoeles come through one of the orbital foramina, roof of the orbit or the medial orbital wall. They tend to displace the globe anteriorly and present with a unilateral exophthalmos. The foramina that can be the pathway are the anterior ethmoidal, posterior ethmoidal, superior orbital fissure, inferior orbital fissure and optic foramen. There were 2 patients in this group.
These encephalocoeles herniate through the floor of the anterior, middle or posterior cranial fossae. In the anterior cranial fossa these are ones that do not present in the nasal or orbital region. The herniation occurs through the ethmoidal, sphenoidal or temporal bones.
The occult ones may present as a mass once they are big enough. These may appear in the auditory canal, nasal cavity, sinuses or posterior pharynx. The occult ones may leak CSF and present with a meningitis.
One needs to have a high index of suspicion and order a CT or MRI scan to make the diagnosis. Sometimes a basal encephalocoele may present as a mass in cleft palate patients. One must resist the temptation to perform a biopsy prior to scanning the patient. There were 11 patients in this group. The majority of these were ethmoidal
with 2 trans-sphenoidal and 1 sphenomaxillary. Fig 5 demonstrates the MRI scan of an ethmoidal encephalocoele.
One may get encephalocoeles assosciated with the northbound Tessier clefts which are the 8-14 clefts (26, 27). The commoner ones are the ones that are paramedian and represent the 11-14 facial clefts which are often associated with hypertelorism. These encephalocoeles may be unilateral or bilateral. The encephalocoele assosciated with a facial cleft 10 presents as a mass in the middle of the eyebrow. There were 25 patients in this group with 27 encephalocoeles. The most common one was those associated with a 1,13 facial cleft (n=15). There were 4 associated with a 0,14 cleft and 5 with a 10 cleft. Fig 6 demonstrates a facial cleft 10 with an accompanying encephalocoele.
One may get a combination of encephalocoeles. These are most commonly seen in the nasal and orbital groups.5 patients had the combination of infranasal and anterior orbital encephalocoeles whilst 4 had supranasal and anterior orbital ones.
These patients were usually operated on at the age of 3 months. If there was a leaking encephalocoele or an imminent leak, this was treated as an emergency and surgery was performed as soon as possible. The rationale was that a CSF leak runs the risk of an infection and the onset of a ventriculitis usually has a fatal outcome.
Fig. 7–9 show pre and postoperative views of patients.
Encephalocoeles are relatively rare deformities and even busy craniofacial units may only see a handful of these cases. In addition there is a vast array of presentations of encephalocoeles. Therefore it makes it difficult to propose management strategies that is based on good clinical trials and scientific evidence. In such rare deformities it may be useful to have a classification system that has clinicopathological relevance. It is akin to the classification of rare facial clefts proposed by Tessier. This would enable better evaluation of procedures and outcomes and have a language and communication that is understood by those in that particular field. Whilst the Suwanela classification is the most comprehensive thus far, there is was no obvious clinicopathological correlation. In addition as these were all post mortem specimens, there was no outcomes based on surgery.
We have proposed a classification based on these cases which has clinicopathological relevance. Present day imaging allows us to more accurately appreciate anatomical changes and pathways of the encephalocoele. This has made it possible for us to plan surgery more accurately and to help us achieve a better outcome. It is a more complete and comprehensive classification that includes patients that have encephalocoeles that were once regarded as ‘theoretical’. This classification has the potential to accommodate newer types of encephalocoeles that are periodically described as case reports.
The occipital and cranial vault groups of Suwanela is grouped as one ‘cranial’ in our proposal. We divide the Suwanela frontoethmoidal group into ‘nasal’ and ‘orbital’. Their cranioschisis group is termed ‘facial cleft’ by us.
The surgical correction of encephalocoeles is a paper on its own. However there are certain principles we employ. Firstly we try and minimize the visible scarring. Therefore a coronal approach is usually used. We try and avoid any incisions on the dorsum of the nose as these are usually apparent. In the nasal group if there is mild to moderate excess skin over the nasal dorsum it has the ability to contract with time. If there is major excess, we use a paranasal incision as these scars are camouflaged in a natural hidden area. If the surgical approach can be performed without a frontal craniotomy, this extracranial method is preferred. Good dural closure and tissue glue is used to obtain a watertight closure. The bony defect is closed with a cranial bone graft. A dorsal nasal bone graft and a medial canthoplasty are performed if required.
This classification system will allow better communication amongst craniofacial teams. It will also afford us the chance to analyse outcomes and procedures on similar groups of patients. Modifications in strategies, staging, timing and technical surgical details will ensue to produce superior clinical outcomes.
A classification of encephalocoeles is proposed that is based on the second largest series to date. This is an updated version of previous classifications that is easy to understand, has clinicopathological relevance, incorporates newer described encephalocoeles and should allow better communication amongst those involved in the care of these patients.
Conflict of Interest
University of Kwazulu Natal. BREC/00001834/2020. Patient consent obtained for photographs.
Air study in infants and children with frontoethmoidal encephalomeningocele.