INTRODUCTION
Disorders of neural tube closure are generally either myelomeningocoele or the less common and less severe meningocoele. Although antenatal screening and the widespread use of peri-conceptual folic acid have reduced the incidence of this debilitating condi- tion it remains a significant part of the pediatric surgeon’s workload. While both types are associated with vertebral body defects the severity of vertebral anomaly is much greater in patients with myelome- ningocoele. Similarly, the extent of associated neuro- logical, bladder, bowel and lower limb abnormalities are significantly greater in this group.
In myelomeningocoele the vertebral arches and overlying vertebral fascia is absent over a variable number of vertebral segments. The spinal cord lies superficially at skin level and cerebrospinal fluid usually leaks from the exposed neural plaque.
Neurological development to the lower limbs, the bladder and the bowel is incomplete and virtually all children with myelomeningocoele have some degree of paralysis of the lower limbs, with sensory loss in addition. Muscle power is imbalanced and results in flexion deformity of the hips and hyperextension of the knees. Bilateral hip dislocation and club foot deformity are common associated problems.
Innervation to the bladder and bowel is abnormal resulting in problems with continence and more typ- ically a neuropathic bladder. The resultant morbidity is significant and affects normal ambulation, preser- vation of renal function, and social continence. The majority of patients have the associated Arnold- Chiari malformation resulting in significant hydro- cephalus requiring a ventriculo-peritoneal shunt in
In meningocoele patients the spinal cord is well covered by an epithelial lined sac. This sac communi- cates with the arachnoid space and contains cerebro- spinal fluid (CSF). Leakage from this sac is rare, as are serious associated abnormalities. Limb innerva- tion is normal and these patients look forward to normal activities. Screening for bladder function is required, however, as a small percentage are at risk of developing a neuropathic bladder.
While the aetiology is not fully known there is a clear genetic link in those of Celtic ancestry. There is an established link between dietary folic acid and neural tube defects and high doses taken peri-con- ceptually confer significant protection.
There are serious ethical factors to consider before any child with a myelomeningocoele under- goes surgical closure. These relate to the quality of life, the anticipated life expectancy of the child and other factors beyond the scope of this chapter. While the majority of children with myelomeningocoele should undergo surgical closure within the first 2 days of life there are a minority with such severe deformity that primary closure may not be indicat- ed. These patients are usually managed by suppor- tive nursing care and closure performed later if the child survives. Before closure, informed consent is obtained from both parents. The lesion is kept clean with chlorhexidene soaks and cleaned of meconium frequently. A pre-operative muscle charting is obtained and a cranial and renal ultrasound per- formed. Consultations are obtained from physiother- apy, orthopedic and social workers where necessary.
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Figure 38.1
Following general anaesthesia and insertion of an endotracheal tube the patient is turned prone and cotton (Gamgee) supports placed under the pelvis and chest. It is important to place additional sup- ports beneath each foot. It is not necessary to have blood available for this procedure but most sugeons
would have a group and hold order with the labora- tory. A neonatal diathermy pad is usually applied to the abdomen or chest. A warming bear-hugger is routinely used. Bipolar diathermy should be used throughout. A swab for culture may be obtained at this point.
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Figure 38.2
The skin is prepped with a povidone iodine solution and the lesion with chlorhexidene and draped with generous margins to facilitate additional skin dissec- tion if required. An incision is made at the lowermost portion of the sac using a sharp scissors or scalpel.
This incision is carried cranially staying away from the neural plaque, which should not be handled where possible, and close to the sac-skin junction.
Incision into the sac results in a release of CSF and some bleeding, which is easily dealt with using bipo- lar diathermy. Nerve roots and blood vessels are now seen traversing the sac and disappearing anteriorly through the dural layer, and they should be pre- served. The dural layer is clearly visible as a whitish fibrous layer. The sac is elevated taking care not to traumatize the neural plaque and the skin excised completely from the plaque. Bleeding from the neu- ral edge is dealt with using biloar diathermy and with minimal handling of the plaque itself. At inter- vals, chlorhexidene soaks may be applied to the area.
Tubal reconstruction of the plaque is rarely indi- cated.
Figure 38.3
The plaque will now be seen to lie on an easily recog- nizable dural layer. This fibrous layer is incised as far laterally as possible and the layer carefully dissected from the underlying fascia. This dissection is carried medially until the nerve roots come into view.
Epidural veins may prove difficult at this point but these can be controlled by bipolar diathermy.
Figure 38.2 Figure 38.3
Martin T. Corbally 416
Figure 38.4
The mobilized dural layer is now tubularized over the exposed neural plaque using a running suture of 6/0 absorbable suture on an 11-mm round-bodied needle. A watertight closure is the expected aim of closure. Occasionally it is not possible to complete the dural tube completely, and a small portion of ver- tebral fascia is used to achieve closure. This is prefer- able to compromising the plaque. A small suction drain is placed to lie lateral to the dural tube and
exited far laterally. This deals with any leakage of CSF, which is usually short lived. Troublesome leak- age usually responds to the insertion of a ventriculo- peritoneal shunt.
Where possible the dural tube is reinforced using an additional fascial covering obtained by mobiliz- ing the fascia from the underlying muscle. It is usu- ally impossible to cover the dural tube completely with fascia especially at the lower end.
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Figure 38.5
The subcutaneous layer is approximated using a 3/0 absorbable suture. It is nearly always possible to close the skin layer using interrupted (4/0) sutures, but occasionally this requires considerable skin
undermining and rarely the use of lateral releasing skin incisions or complex flap repairs. The skin clo- sure is supported with wound strips and a dressing applied.
Figure 38.5
Martin T. Corbally 418
CONCLUSION
The baby is nursed prone or in a lateral position.
Careful attention is paid to keeping the area clean.
Feeds are not restricted. Weekly estimates of head circumference are performed and this is supple- mented with cranial ultrasound to monitor progress of the associated hydrocephalus. A ventriculo-peri- toneal shunt is inserted when the head circumfer- ence rises precipitously or when the ventricular diameter increases beyond 50–60% of the diameter of the skull.
Other surgical considerations include:
쐽 Associated vertebral kyphosis may occasionally require an osteotomy to facilitate closure in the primary setting. This is more likely with lesions treated conservatively initially and back closure performed as a secondary event.
쐽 Meningocoele is closed as an elective procedure.
Since there is no exposure of neural elements, clo- sure is straightforward with sac excision and clo- sure over a drain.
Patients with spina bifida pose serious problems to the family and the medical profession. They there- fore need a multidisciplinary approach for their management with special emphasis on monitoring of renal and bladder function, provision of physio- therapy services both in the community and hospi- tal, proper evaluation of hearing and visual acuity, orthopedic review and assistance with mobility either using callipers or modified wheelchair. In addition, the mobilization of local pediatric and medical services with input from social services is vital to optimize their ultimate quality of life. Quality of life in these patients can be actively enhanced using clean intermittent catheterization and bowel washout programmes.
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Muraszko KM (1995) Myelomeningocoele. In: Spitz L, Coran AG (eds) Pediatric surgery. Chapman & Hall, London, pp 787–795
Puri P, Surana R (2003) Spina bifida and encephalocele. In:
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