With translational purposes, since January 2004 we have developed a novel foetal procedure in a sheep model that avoids foetal tissue manipulation. The technique consists in a gentle coverage of the defect using an inert patch sheet secured by a surgical sealant. results in the animal model showed adequate protection of the spinal cord and prevention of the Chiari malformation. Later on, this technique has been used in two human foetuses.
Foetal repair was done in August 2008 by means of closure of the dural sac and coverage with a patch of collagen-elastin matrix) secured with surgical sealant. Birth delivery happened at 31 weeks due to uterine rupture in the scar from a previous c-section. At birth, the newborn weighted 1.5Kg, and showed a complete closure of the defect without leakage of cerebrospinal fluid, and normal legs mobility. Cranial MRI showed small cerebelar herniation and small ventricular dilatation. One year after birth the baby is able to walk, but the ventricular dilatation has progressed and a shunt was placed on at 11 months of life.
Foetal repair was made in January 2009 by means of closure of the dural sac and coverage with a patch secured with surgical sealant. Birth delivery was done at 30 weeks due to oligoamnios. At birth the newborn weighted 1Kg, and showed closure of the defect without leakage of cerebrospinal fluid, and normal legs mobility. Cranial MRI showed correction of the Chiari malformation and no ventricular dilatation. Eight months after birth the baby is fine and stable.
Amniotic band syndrome (ABS) is a congenital disorder characterized by limb constrictions. The disorder lacks precise definition, and its exact pathogenesis is unknown. Though theories have been advanced to explain the condition’s origin, none have been scientifically validated. The “exogenous” theory, popularized by Torpin, is the most widely accepted. It suggests that early amniotic rupture leads to formation of amniotic strands, which by means of progressive compression induce formation of extremity bands. In this disorder, histological examination of the excised bands demonstrates them to be composed of fibrous tissue. Multiple clinical and experimental data reveal this theory has only low plausibility. Our purpose is to assess whether annular external compression of a fetal rabbit limb will produce a band of subcutaneous fibrous tissue characteristic of amniotic band syndrome. We operated on one limb of 10 different rabbit fetuses, each at 21 days of gestation. The extremity was ligated with a nylon suture at the infracondylar level. At 30 days gestation, each fetus was delivered by caesarean section. Limbs were analyzed histologically using different techniques. Histological analysis did not show subcutaneous fibrous tissue in the mechanically constricted zone. The distal segment showed dilatation of lymphatic vessels and edema of soft tissue. Annular external compression of a fetal rabbit limb does not induce development of new fibrous tissue; therefore this experimental study does not support the theory of a mechanical exogenous pathogenesis in amniotic band syndrome.
The continuous leakage of cerebrospinal fluid in the mielomeningocele (MMC) area produces the Chiari II malformation. The aim of our study was to assess the effect of preterm delivery and prenatal corticosteroids administration in the degree of Chiari malformation. Seventy-five out of 148 foetuses from 17 pregnant New Zealand White rabbits underwent lumbar three-level laminectomy and wide opening of dura-mater (surgical MMC). Animals were distributed in five groups: group T, foetuses with MMC, delivery at term and no other treatment; group TC, foetuses with MMC, delivery at term and prenatal administration of corticosteroids; group P, foetuses with MMC, delivery preterm and no other treatment; group PC, foetuses with MMC, delivery preterm and prenatal administration of corticosteroids; group C, controls. The degree of herniation was measured in percentage of decrease of the cerebellum between the inferior limit of the skull and the superior limit of the first vertebra, and compared among groups. We obtained 7T, 5TC, 10P, 6PC, and 28C alive newborns. All groups with prenatal delivery or prenatal corticosteroids showed statistically significant minor degree of herniation than T-group: group TC IC 95% between 25.7 and 47.2% minor (p=0.000), group P IC 95% between 30.4 and 47.7% minor (p=0.000), group PC IC 95% between 32.6 and 55.4 minor (p=0.000). There were no statistically significant differences among groups TC and P (p=0,577), TC and PC (p=0,227) or P and PC (p=0,311). Preterm delivery and prenatal administration of corticosteroids, together or separately, result in lower degree of Chiari malformation in a model of surgical MMC in rabbit fetuses.
Open fetal surgery for reparation in myelomeningocele reverses Chiari II malformation and protects exposed neural elements from secondary lesion, but the technique is associated with a high rate of complications. The aim of our study was to assess whether a simple and fast technique of coverage produces the same results as a complete and longer technique of reparation in terms of neural protection. Twelve sheep’s foetuses underwent lumbar three-level laminectomy and opening of the dura-mater on the 75th day of the gestation. Four of them were not-repaired (NR group). Eight of them underwent coverage with inert material sheet and synthetic surgical sealant on the 95th day (R group). At birth, clinical and histological examination and comparison between groups was performed. None NR animal were able to stand or to walk nor had sphincter continence; all of them showed a wide defect of closure in the lumbar area, continuous leakage of cerebrospinal fluid (CSF), and histological neural damage; the mean vermis herniation was 75%. All R animals were able to stand and to walk and all of them showed sphincter continence; none of them showed leakage of CSF and showed coverage of the 93% of the defect; all of them showed regeneration of dura-mater, muscle and skin; the mean vermis herniation was 10%. A simplified technique of coverage produces the same clinical results than a more complex reconstruction in a model of surgical MMC in sheep and the histological study reveals the regeneration of several layers of soft tissues.
* Posterior portal: anterior branch of the axillary nerve and posterior circumflex artery 3.4 cm (range: 1.4 – 5); cutaneous branch of the axillary nerve 6.3 cm (range: 3.8 – 8.3), suprascapular nerve 2.8 cm (range: 2.1–3.3). * Anterosuperior portal: main branch of the musculocutaneous nerve 6.5 cm (range: 3.8 – 11). * Lateral subacromial portal: axillary nerve and posterior circumflex artery 3.7 cm (range: 2– 5.5). * Anteroinferior subaxillary portal 4 cm (range: 3.1 –6). * Supraspinatus portal: suprascapular nerve 3.2 cm (range: 2.4 – 4).