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|SPECIAL NI FEATURE
|Year : 2020 | Volume
| Issue : 1 | Page : 5-8
Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi-16, India
|Date of Web Publication||28-Feb-2020|
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Tandon P N. Meningo-Encephalocoele. Neurol India 2020;68:5-8
Between the extremely rare occurrence of cranium bifidum occultum and congenital absence of skull and scalp, and the relatively common incidence of anencephaly, are a variety of developmental anomalies involving the scalp, the skull, the meninges and the brain to varying extent. During a short period of three-and-a-half years in a general neurosurgical unit a relatively unusual number of these cases was seen. On discussing this problem with several visitors from abroad and also with senior colleagues in this country it became apparent that this high incidence might be due to geographical predisposition, in view of the paucity of detailed reports in the literature, it was decided to record this experience. The different types of anomaly are shown in Table I.
| » Occipital Encephalocoele|| |
Encephalocoeles are commonest in the occipital region. [Figure 1] shows some of the anatomical variations noted by us in this series. The bony defect and the protrusion may be above the external occipital protuberance or below it [Figure 2] and [Figure 3]. However, in three of our patients the defect was both above and below this point. In one of these, the herniation of the meninges was through the entire defect and it contained the occipital lobe above and the cerebellum below [Figure 1]. In the other two, the external protrusion was below the region of the external occipital protuberance, but the much bigger and broader bony defect above this was occupied by a soft diffuse cystic bulge. This, on exploration, proved to be due to an associated intracranial extension of the meningocoele through the tentorium [Figure 1]. This intracranial extension is liable to produce internal hydrocephalus by compressing and obliterating the foramina of Magendie and Luschka. Failure to recognise this intracranial component of an obvious pedunculated meningocoele will certainly lead to a bad Post-operative result.
|Figure 1: Diagram showing some of the anatomical variations in cases of occipital encephalocoeles|
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|Figure 2: Photograph of a child with an occipital encephalocoela situated above the external occipital protuberance|
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|Figure 3: Photograph of a child with an occipital encephalocoele protruding below the external occipital protuberance|
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Another factor to consider in planning the treatment of these malformation is their size and content. If the bulk of the contents is fluid, with only a knuckle of brain tissue protuding into the sac, operation may be worthwhile even in the presence of a huge swelling. [Figure 4] and [Figure 5] are photographs of a child with a huge occipital encephalocoele before and after operation. At operation there was only very little neural tissue protruding into the sac. On the other hand, if herniated brain constitutes the main mass, it is doubtful whether surgery is worth undertaking. Besides, sudden loss of fluid during operation upon these huge cystic meningocoeles may prove shocking for the child. Pre-operative gradual decompression by repeated aspiration or slow continuous drainage considerably reduces this risk.
|Figure 4: Photograph of a child with an huge encephalocoele, which contained very little neural tissue|
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The state of intracranial CSF pathways plays a decisive role in the ultimate outcome of these cases. Ventriculography is therefore advisable. Patterns varying from the nearly normal to the grossly hydrocephalic are seen. In the presence of the latter surgery would be futile.
Occasionally there may be other congenital anomalies of the central nervous system associated with the encephalocoele. Thus one of our patients had a congenital dermal sinus 3 to 4 cm. above an occipital encephalocoele. The sinus could be traced through the sagittal sutures to the dura. In another patient an occipital encephalocoele was associated with a lumbar meningomyelocoele neurological deficit.
| » Nasal Meningo-Encephalocoele|| |
There was a surprisingly high incidence of these lesions in this series [Table 1]. Whether or not there was a generally higher incidence of encephalocoeles in the population serviced by this centre is debatable, but the relatively high incidence of “nasal” Jesion cannot be ignored. Thailand is the only other region from where such a high incidence is reported.
The different types of nasal encephalocoeles are illustrated in [Figure 6].
|Figure 6: Diagram illustrating the different varienties of nasal encephalocoeles|
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Fronto-nsal The hernia takes place through the defect at the junciton of the frontal and the nasal bone. The swelling is usually globular and presents at the bregma [Figure 6]I.
Fronto-ethmoidal The defect is region of the foramen caecum just anterior to the crista galli. The herniating mass lies deep to the nasal bone, making its appearance at the junction of the nasal bone and the nasal cartilage. The swelling is usually lobulated, overriding the bridge of the nose [Figure 6] and [Figure 7].
Nasopharyngeal These present as a nasal polyp, the bony defect being in the region of the cribriform plate [Figure 6], III].
In the nasal region, unlike the occipital, it is important to know before operation the exact site of the bony defect. The fronto-nasal variety can be satisfactorily dealt with through an extracranial approach. The neck of the sac is excised at the fronto-nasal junction, and the defect is repaired by a periosteal flap. In case of a big defect tantalum or stainless steel wire-mesh may be required. On the other hand, in the fronto-ethmoidal and nasopharyngeal encephalocoeles, the neck of the sac cannot be reached through an exracranial approach. To repair the defect, in these cases, a bifrontal craniotomy is essential. Both frontal lobes are elevated and the defect is outlined. As a rule both frontal poles are seen herniating through the defect. It may not be possible to deliver these intracranially, necessitating amputation of the herniating poles. These are then dealt with extracranialy, either at the same, or usually at a second operation. To cover the bony defect it has been recommended to turn a flap of dura overlying the orbital plate. In our experience this was found to be unsatisfactory; we have therefore, used autogenous fascia lata graft. Even then, one patient had a recurrence and it was felt that in the future wire-mesh reinforcement should be routinely used. So far, there has been no recurrence of an occipital encephalocoele, even though at times simple dural closure was performed after excision of the sac. No explanation can be offered for this special predilection for recurrence of fronto-ethmoidal encephalocoeles. Results are also cosmetically discouraging [Figure 7] and [Figure 8]. The nose is elongated, there is an unsightly depression at the junction of the bony and cartilagcnous part, and the redundant skin flaps with inspiration. All require secondary plastic reconstruction of the nose.
The general principles regarding the assessment of the contents of the encephalocoele, the state of intracranial CSF pathways and the presence or absence of associated anomalies apply as much to this group of lesions as to the occipital ones.
In spite of superficial similarities, each case should be assessed carefully in all its details before surgery is planned. Even after this, some unpredictable elements remain. Some children, though apparently well after surgery, fail to thrive normally, others remain mentally retarded and a few develop hydrocephalus.
I am grateful to the Principal and Superintendent, K. G. Medical College, Lucknow for permission to use the case records of patients included in this paper. All patients were under the author's care in the above-mentioned institution.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| » References|| |
Ingraham, F. D. and Matson, D.D., Neurosurgery of infancy and Childhood,
Charles C. Thomas, Springlfield, Illinosis 1954, p.49.
Sunwanwela, C. and Hongsprabhas, C., Fronto-Ethmoidal Encephalomeningocoele, Excerpta Med., (International Congress Series), 93, 165, 1965.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]