Management of hydromyelia

The authors review their experience in the management of 22 patients with hydromyelia over a 26-month period. Ten children had Chiari I malformations and hydromyelia; 4 children had myelomeningoceles (3 with large thoracic spinal cord cavitations and 1 with cervical hydromyelia); 6 children had distal hydromyelia associated with tethered cords and occult dysraphism; and 2 patients had cavitation subsequent to arachnoiditis. All patients were investigated preoperatively with MRI and intraoperatively with ultrasound. These neurodiagnostic examinations dictated the type of surgical intervention. Patients with Chiari I or Chiari II malformations, cervical hydromyelia, or basal arachnoiditis underwent decompression of the hindbrain malformations, myelotomy with drainage of the cyst, and placement of a stent. When the area of hydromyelia extended to the obex, as demonstrated by intraoperative ultrasound, the obex was plugged. Cyst-pleural shunts were placed in the children who had myelomeningoceles and thoracic hydromyelia. Patients with distal hydromyelia underwent modified terminal ventriculostomy. The classical presentation of brachial amyotrophy and dissociated sensory loss was present in only 3 patients. Progressive scoliosis without neurological deficit, pain, and Lhermitte's phenomenon were common presentations. The patients with tethered cords were generally asymptomatic from their cysts. The authors discuss operative technique, utilization of intraoperative ultrasound, and surgical outcome.     

Lumbar canal stenosis: a cause of late neurological deterioration in patients with spina bifida

BACKGROUND: Patients diagnosed with spina bifida may show late deterioration. This worsening in their clinical symptoms has been attributed to a multiplicity of causes such as secondary tethering of the spinal cord, Chiari II anomaly, hydromyelia, diastematomyelia, arachnoid cysts, and dermoid tumors. METHODS: We searched the clinical records of patients diagnosed with spina bifida who were treated at our hospital for a period of 25 years for the purpose of ascertaining the number and etiology of cases of late neurological deterioration. RESULTS: Six of 144 patients with open spina bifida presented with late neurological deterioration. In one of these cases and in another patient with occult spina bifida the most relevant factor noted during surgery was the presence of marked lumbar canal stenosis. CONCLUSION: We suggest that certain cases of late clinical worsening in spina bifida patients are because of lumbar canal stenosis and that this condition should be added to the list of causes that may produce delayed neurological deterioration in patients with spinal dysraphism.     

14 cases of communicating syringomyelia associated with Chiari I malformation in children]

The authors review their experience of 14 children with syringomyelia and associated Chiari I malformation observed during the last 21 years. Initial symptoms were motor weakness (57%), sensory signs (50%), scoliosis (50%) and bladder dysfunction (21.5%), while signs of admission were pyramidal signs (78.5%) with motor deficit (43%), spinal deformities (64.2%), syringomyelic syndrome (36%) and sensory deficit (21.5%). Four children were investigated with myelography, three with myelography and spinal CT Scan and the last seven cases with MRI. Ten children (71.4%) underwent a decompression of the Chiari malformation with or without drainage of the cyst and shunting of an associated hydrocephalus. Syringo-peritoneal shunts were used in 3 children and laminectomy with syringo-subarachnoid shunt in 1 case. The neurological symptoms improved in 57% of the cases, 2 patients deteriorated and 4 patients were lost to follow-up. The authors discuss the clinical symptomatology, the MRI study, the controversies concerning the treatment and concluded with their attitude concerning this pathology in children.     

Corrección intrauterina de mielomeningocele: experiencia del programa de medicina y terapia fetal del Hospital Universitario Virgen del Rocío

The most frequent form of spina bifida is myelomeningocele. There is no optimal postnatal treatment for this defect. In addition to the motor or sensory deficits, which depend on the location of the lesion, the defect is usually associated with Chiari ii malformation in affected children. Myelomeningocele has high mortality and, in up to 80% to 90% of patients, can be accompanied by hydrocephalus, which causes severe neurocognitive impairment and requires the patient to be shunted for survival. Intrauterine repair of fetal malformations employing open access through hysterotomy has become a therapeutic option due to improved anesthetic and surgical techniques and instrumentation, which have allowed this type of intervention to become relatively frequent. Anesthetic treatment should focus on both the mother and fetus and the hemodynamic factors regulating placental flow, uterine dynamics, blood loss and fetal well-being must remain well-controlled. Within our Program for Fetal Medicine and Therapy, 21 open fetal interventions have been performed: 17 EXIT procedures and 4 procedures for the intrauterine correction of fetal myelomeningocele. We describe our experience of the intrauterine repair of fetal myelomeningocele through open fetal surgery.     

Brain stem auditory evoked potentials in Arnold-Chiari malformation: possible prognostic value and changes with surgical decompression

Symptomatic Arnold-Chiari malformation (Chiari II) is a recently described clinical entity, the natural history and surgical management of which remain controversial. The brain stem auditory evoked potentials (BAEPs) have been described as abnormal in 50 to 86% of children with myelomeningocele. We present the case of a full-term infant with myelomeningocele, shunted hydrocephalus, and Chiari II malformation who was surgically treated by decompression when she was 3 weeks old. BAEPs recorded immediately after decompression showed dramatic improvement over BAEPs recorded immediately before decompression, an improvement that could not be attributed to maturation of the central nervous system. It is postulated that in further large series the degree of abnormality in BAEPs may be of value in predicting the clinical course of these patients. The current status of BAEPs as they apply to the evaluation of posterior fossa anomalies is reviewed.     

Brainstem dysfunction in chiari malformation presenting as profound hypoglycemia: presentation of four cases, review of the literature, and conjecture as to mechanism.

OBJECTIVE: We report four patients whose cases resulted in our observation that profound hypoglycemia resulting from intermittent hyperinsulinism plays a significant role in patients with brainstem dysfunction from Chiari I or II malformations who have intermittent autonomic dysfunction ("blue spells"). METHODS: The records of four children with severe brainstem dysfunction associated with hindbrain herniation (Chiari I or II malformation) were reviewed retrospectively. Each patient had severe lower cranial nerve dysfunction that required tracheotomy and feeding tube placement. After we found that profound hypoglycemia had occurred during a spell of autonomic dysfunction in one patient, the charts of the other three patients were reviewed for evidence of hypoglycemia. Now, whenever one of them has evidence of autonomic dysfunction, prospective studies of glucose and insulin levels are performed. Three of the patients had Chiari II malformation in association with myelomeningocele, and one patient had a Chiari I malformation resulting from Pfeiffer's syndrome. RESULTS: Hypoglycemia occurred in these patients episodically, and usually when their shunts were functioning. The hypoglycemia was associated with hyperinsulinemia in each patient. The brainstem structures of these children (presumably the dorsal motor nuclei of the vagus) were extremely sensitive to changes in local or regional intracranial pressure. These changes were triggered by intermittent shunt failure, agitation from pain, abdominal distention from constipation, and retention of CO2. In patients with Chiari malformations, even mild increases in intracranial pressure lead to brainstem dysfunction. One possible explanation is that pressure on the deformed Xth cranial nerve nuclei may lead to insulin release and life-threatening hypoglycemia. Continuous-drip feeds are necessary to prevent this complication. CONCLUSION: Patients with severe intermittent brainstem dysfunction after decompression of Chiari I or Chiari II malformations should have laboratory studies of glucose levels performed at the time of the episodes to rule out hypoglycemia.     

Outcome following hindbrain decompression of symptomatic Chiari malformations in children previously treated with myelomeningocele closure and shunts.

Between 1975 and 1989, 25 children treated with myelomeningocele closure and shunting for hydrocephalus at the Children's Hospital of Pittsburgh developed progressive lower brain-stem dysfunction from their Chiari malformation. Retrospective univariate and multivariate analyses of these cases were undertaken to assess the relationship between preoperative clinical factors and postoperative outcome. Since earlier reports have suggested that neonates with symptomatic Chiari malformations show a less favorable response than older children to craniocervical decompression, particular attention was directed at examining the effect of age on preoperative symptoms and postoperative outcome. Patients were subdivided by age into two groups, namely: 13 patients who became symptomatic before 2 months of age (neonatal group) and 12 older infants and children who developed initial symptoms between 6 months and 10 years of age. Once symptoms developed, patients in both groups deteriorated progressively until brain-stem decompression was performed. The mode of presentation and the rate and extent of neurological deterioration differed substantially in the two groups. Whereas the neonates typically showed rapid neurological deterioration and often manifested profound brain-stem dysfunction within a period of several days, the older patients experienced a more insidious symptom progression and rarely demonstrated the severe degree of impairment seen in the neonates. All patients underwent suboccipital craniectomy, cervical laminectomy, and dural decompression. A shunt from the fourth ventricle and/or syrinx to the subarachnoid space was placed in those with significant syringomyelia. Following surgery, 17 patients had complete or nearly complete resolution of all signs of brain-stem compression, three had mild to moderate residual deficits, and five showed no improvement. Outcome correlated closely with the preoperative neurological status. In particular, the presence of bilateral vocal cord paralysis was associated with a poor response to surgery (p < 0.001 on both univariate and multivariate analyses). Of the six patients (all neonates) who progressed to complete bilateral vocal cord paralysis before surgery, only one improved. In contrast, all patients with less profound but nonetheless severe deficits recovered function postoperatively. Although the neonates as a group had a poorer outcome than did the older patients (p = 0.02 on univariate analysis), this in large part reflected their more severe preoperative impairments; neonates who still had some preservation of vocal cord function before surgery subsequently did as well as the older patients. Accordingly, age did not prove to be an independent prognostic factor on multivariate analysis. Taken together, these results indicate that, in most patients with symptomatic Chiari II malformations (including neonates), neurological deficits are potentially reversible if hindbrain decompression is performed expeditiously.     

Chiari malformation with syringocephaly. Case report

A 69-year-old white woman presented with a left hemiparesis which progressed to quadriparesis and encephalopathy. Computerized tomography and magnetic resonance imaging revealed a Chiari I malformation and a hydromyelic cavity extending from C-2 to T-6. Rostrally, the cavity extended through the ventral medulla, pons, and right cerebral peduncle into the right cerebral hemisphere, where the cavity enlarged and was associated with mass effect. The patient has made a dramatic neurological recovery following suboccipital craniectomy with insertion of a dural graft to decompress the Chiari malformation and upper cervical laminectomy and dorsal root entry zone myelotomy to decompress the hydromyelia.     

Acute presentation of hydromyelia in a child

Summary The authors document a rapid development, within 3 weeks, of hydromyelia in a 12 year-old boy. The boy was admitted to a local hospital because of drowsiness and persistent severe neck pain. Neurological examination disclosed a lethargic boy with no neurological deficit other than Parinaud’s sign. During his transfer to our department, he presented a cardio-respiratory arrest with coma and bilateral mydriasis. External ventricular drain and craniocervical decompression achieved excellent clinical and neuroradiological outcomes. The development of hydromyelia in this case is caused by obstruction to the natural cerebrospinal fluid pathway at the craniocervical junction and the cardio-respiratory arrest is provoked by a brain stem compression against the clivus and odontoid process. This report illustrates that hydromyelia may complicate acute obstructive hydrocephalus due to acquired Chiari malformation.     

Intraspinal anomalies in myelomeningocele

This study reports the results of MRI analysis of the spinal cord in 83 patients with myelomeningocele. 63 patients had a "tethered cord" or a "suspected tethered cord". In 14 cases we found a "hydro-/syringomyelia". In only 2 cases there were no pathological findings. The influence especially of the "tethered cord" and the "hydro-/syringomyelia" on the development of deformities of the locomotor apparatus is discussed. Concerning this problem the experience reported in the literature is not sufficient enough to make final statements. However, in cases of deterioration of the neurological status in patients with myelomeningocele the influence of intraspinal anomalies should be considered giving rise to further diagnostic examinations.     

Long-term outcome of surgical management of adult Chiari I malformation

Chiari I malformation continues to inspire controversy. Debate still exists about surgical options. The aim of this study is to evaluate the long-term outcome of posterior fossa decompression procedure (PFD) in the treatment of adult Chiari I malformation, focusing on some factors or technical aspects which might influence the outcome. Forty-six adult patients with Chiari I malformation operated by PFD are the subject of this study. The group included 21 males and 25 females, with mean age of 37.4?years. Patients were divided into two groups: group I (32 cases) with syringomyelia and group II (14 cases) without syringomyelia. Group I was further subdivided into three subgroups according to the surgical procedure adopted: group Ia (12 cases) operated by PFD only, group Ib (14 cases) operated by PFD with fourth ventricular shunt, and group Ic (six cases) operated by PFD and syringosubarachnoid shunt. All cases included in group II were operated by PFD only. In group I, symptoms improved in 14 cases (43.8?%) and stabilized in 18 cases (56.3?%), whereas in group II, symptoms resolved in ten cases (71.4?%) and improved in four cases (28.6?%). Postoperative magnetic resonance imaging showed that the syrinx was resolved in 21 cases (65.6?%), improved in seven cases (21.9?%), and unchanged in four cases (12.5?%). Among the mean follow-up period (5.8?years), recurrence of symptoms occurred in five cases (10.9?%), all of them are included in group I, and were reoperated again. Posterior fossa decompression is recommended as the treatment of choice in adult Chiari I malformation with or without syringomyelia. The presence of syringomyelia predicts a less favorable response to surgical intervention. Syringosubarachnoid shunting did not improve the long-term outcome either clinically or radiologically. Implanting a fourth ventricular shunt in cases of syringomyelia associated with adhesions at the foramen of Magendie decreases the long-term incidence of recurrence significantly. For recurrent cases, re-exploration of the initial posterior fossa decompression is recommended before any consideration is given for direct management of the syrinx.     

Magnetic resonance imaging of the spinal cord in spinal dysraphisms

Magnetic resonance imaging (MRI) was performed 49 times in 42 patients with spinal dysraphism. Scoliosis and a changing neurological picture were the primary indications. Spinal cord anomalies included hydromyelia, diastematomyelia, lipoma, thickened filum terminali, and spinal cord atrophy. All but one patient exhibited Arnold-Chiari malformation. Twenty-two of the 42 patients had computed tomography (CT) scans, myelograms, or operations that corroborated the 41 MRI findings. Three false-positive MRI findings of hydromyelia and no false-negative studies were observed. MRI is a noninvasive investigative technique that provides more information than myelography or CT in defining spinal cord anatomy in spinal dysraphism.     

Chiari Type I malformation with hydromyelia: findings at computerized metrizamide ventriculomyelography.

Computerized Metrizamide ventriculomyelography consists of CT exploration of the head and neck performed one hour after introduction of Metrizamide into the lateral ventricle via a frontal burr hole. This procedure permits visualisation of all soft-tissue anomalies present in Chiari malformation with hydromyelia as seen in two cases.     

The nature of congenital posterior cervical or cervicothoracic midline cutaneous mass lesions. Report of eight cases

Between 4% and 8% of cases of spina bifida cystica occur in a cervical or cervicothoracic location. Despite a large body of literature concerning spinal dysraphism, there has been little written specifically about patients afflicted with this disorder in a cervical location. Eight children who presented at birth with posterior cervical or cervicothoracic lumps, all of which represented a dysraphic state, are discussed. Two types of abnormalities were noted. Three patients had hydromyelia with an associated myelocystocele herniating posteriorly into a meningocele sac. In these three patients there was an associated Chiari II malformation and hydrocephalus. The other five children had a meningocele in which a band of tissue extended from the posterior aspect of the spinal cord through a defect in the bone and fascia to the posterior part of the meningocele sac itself. No patient had a lesion that could be described as a meningomyelocele. The investigation and surgical management of these conditions are discussed and the need for intradural exploration to untether the spinal cord in the cervical region is stressed.     

Chiari I malformation associated with atlanto-axial dislocation: focussing on the anterior cervico-medullary compression

Summary Background. Chiari I malformation with atlantoaxial dislocation may cause both posterior and anterior cervicomedullary compression. We studied the clinicoradiological features and surgical outcome in patients having Chiari I malformation with atlantoaxial dislocation. Method. Thirty-nine patients with Chiari I malformation with atlanto-axial dislocation underwent preoperative and follow-up neurological status assessment. In Chiari I malformation with reducible atlanto-axial dislocation (n = 11), a direct posterior stabilization was done. In Chiari I malformation with irreducible atlanto-axial dislocation (n = 28), a single stage transoral decompression with posterior stabilization and/or posterior decompression and duraplasty were done in 18 patients. In 10 patients, only posterior decompression and/or posterior stabilization was performed. Seven among the latter patients subsequently deteriorated and required transoral decompression. Comparison of mean neurological status scores of patients with Chiari I malformation with irreducible atlanto-axial dislocation who underwent single stage transoral decompression with posterior stabilization versus the posterior procedure alone was done using T-test and proportional significance also calculated. Findings. Patients with Chiari I malformation with atlanto-axial dislocation have a high incidence of long tract signs and sphincteric disturbances with a decrease in the mean foramen magnum diameter. The mean neurological status scores of patients with Chiari I malformation with irreducible atlanto-axial dislocation who underwent single stage transoral decompression with posterior stabilization were significantly better than those patients who underwent the posterior procedure alone. The latter patients also showed significant clinical improvement following transoral decompression. In the presence of Chiari I malformation with reducible atlanto-axial dislocation, reduction and stabilization of atlanto-axial dislocation resulted in neurological improvement. The follow up neurological status scores of these patients improved after surgical intervention even in the presence of poor preoperative grades. Conclusions. Patients with Chiari I malformation should be investigated for the presence of atlanto-axial dislocation. In case atlantoaxial dislocation coexists, priority must be given to relieving anterior cervicomedullary compression.     

One-stage and posterior approach for correction of moderate to severe scoliosis in adolescents associated with Chiari I malformation: is a prior suboccipital decompression always necessary?

Priority of neurological decompression was regarded as necessary for scoliosis patients associated with Chiari I malformation in order to decrease the risk of spinal cord injury from scoliosis surgery. We report a retrospective series of scoliosis associated with Chiari I malformation in 13 adolescent patients and explore the effectiveness and safety of posterior scoliosis correction without suboccipital decompression. One-stage posterior approach total vertebral column resection was performed in seven patients with scoliosis or kyphosis curve >90° (average 100.1° scoliotic and 97.1° kyphotic curves) or presented with apparent neurological deficits, whereas the other six patients underwent posterior pedicle screw instrumentation for correction of spinal deformity alone (average 77.3° scoliotic and 44.0° kyphotic curves). The apex of the scoliosis curve was located at T7–T12. Mean operating time and intraoperative hemorrhage was 463 min and 5,190 ml in patients undergoing total vertebral column resection, with average correction rate of scoliosis and kyphosis being 63.3 and 71.1%, respectively. Mean operating time and intraoperative hemorrhage in patients undergoing instrumentation alone was 246 min and 1,450 ml, with the average correction rate of scoliosis and kyphosis being 60.8 and 53.4%, respectively. The mean follow-up duration was 32.2 months. No iatrogenic neurological deterioration had been encountered during the operation procedure and follow-up. After vertebral column resection, neurological dysfunctions such as relaxation of anal sphincter or hypermyotonia that occurred in three patients preoperatively improved gradually. In summary, suboccipital decompression prior to correction of spine deformity may not always be necessary for adolescent patients with scoliosis associated with Chiari I malformation. Particularly in patients with a severe and rigid curve or with significant neurological deficits, posterior approach total vertebral column resection is likely a good option, which could not only result in satisfactory correction of deformity, but also decrease the risk of neurological injury secondary to surgical intervention by shortening spine and reducing the tension of spinal cord.     

Syringomyelia, its pathogenesis and surgical treatment based on 4 cases' experience

Four cases of syringomyelia, each were considered to have different pathogenesis of syrinx and presented different clinical and radiological pictures, are reported. Case I was associated with Chiari I malformation and the syrinx communicated with the fourth ventricle through the central canal, case 2 was associated with Chiari II malformation and the syrinx was not communicated with the fourth ventricle, case 3 was thought to be traumatic and case 4 to be arachnoiditis due to unknown etiology. Metrizamide CT myelography was most valuable diagnostic technique to disclose the syringomyelic cavity and its extension. The cases except case 1 showed central opacification without via fourth ventricle, suggesting transneural migration CSF as shown by Aubin et al. Surgical treatment, therefore, was different in each case to obtain normal CSF dynamics. Case 1 was treated by suboccipital craniectomy, muscle plugging to the obex and syringo-subarachnoid shunt. In case 2 syringo-cisternal shunt was done in addition to suboccipital craniectomy. In case 3 syringocisternal shunt was done after laminectomy. In case 4 syringo-peritoneal shunt was performed. All but case 4 were obtained favorable result and case 4 was unfavorable except the disappearance of girdle sensation. For traumatic or inflammatory syringomyelia with tight adhesion between pia and arachnoid membrane in subarachnoid space, syringocisternal shunt was good way to obtain normal CSF dynamics and was expected to relieve the neurological deterioration.     

Neurogenic dysphagia resulting from Chiari malformations.

Between 1980 and 1989, 15 of 46 patients (11 children, 4 adults) who underwent suboccipital craniectomy and cervical laminectomy for symptomatic Chiari malformations presented with manifestations of neurogenic dysphagia. Each of these patients had normal swallowing function before the development of dysphagic symptoms. Dysphagia was progressive in all 15 and, in most cases, preceded the onset of other severe brain stem signs. The rate of symptom progression varied depending on the age of the patient. Whereas the six infants (all Chiari II) deteriorated rapidly after the onset of initial symptoms, the five older children (two Chiari I, three Chiari II) and four adults (all Chiari I) showed a more gradual deterioration. In 11 patients with severe dysphagia, barium video esophagograms, pharyngoesophageal motility studies, continuous esophageal pH monitoring, and appropriate scintigraphic studies were useful in defining the scope of the swallowing impairment and determining whether perioperative nasogastric or gastrostomy feedings, gastric fundoplication, and/or tracheostomy were needed to maintain adequate nutrition and avoid aspiration. These patients all had widespread dysfunction of the swallowing mechanism, with a combination of diffuse pharyngoesophageal dysmotility, cricopharyngeal achalasia, nasal regurgitation, tracheal aspiration, and gastroesophageal reflux. The pathophysiology of these swallowing impairments and their relation to the hindbrain malformation is discussed. Postoperative outcome with regard to swallowing function correlated with the severity of preoperative symptoms. The four patients with mild dysphagia showed rapid improvement in swallowing function after surgery. Seven patients with more severe impairment but without other signs of severe brain stem compromise, such as central apnea or complete bilateral vocal cord paralysis, also improved, albeit more slowly. In contrast, the outcome in the four patients who developed other signs of severe brain stem dysfunction before surgery was poor. Early recognition of neurogenic dysphagia and expeditious intervention are therefore crucial in ensuring a favorable neurological outcome.     

Syringobulbia Caused by Delayed Postoperative Tethering of the Cervical Spinal Cord – Delayed Complication of Foramen Magnum Decompression for Chiari Malformation

Summary  Postoperative tethering of the high cervical spinal cord is a rare cause of neurological deterioration after foramen magnum decompression (FMD) with duraplasty for Chiari type I malformation. A review of the literature revealed that only 5 cases have been reported. This entity is not widely known to occur as a complication of the common surgical procedure for Chiari type I malformation. A 17-year-old boy experienced rapidly progressive neurological deterioration over a 3-month period. FMD and duraplasty with lyophilized cadaver dura had been performed 8 years previously. Follow-up MR images showed that the cerebrospinal fluid (CSF) space dorsal to the cord was gradually disappearing and that syringobulbia had developed. Opening the dura mater of the posterior fossa revealed dense fibrous scarring, arachnoid thickening over the cervicomedullary area, and tethering the cord to the dura from the medulla to C2. The adhesions were dissected free, and the tethering was released. A syringosubarachnoid (SS) shunt was inserted and duraplasty was performed with an expended polytetrafluoroethylene sheet (Gore-Tex). Postoperative MR images demonstrated that the syringobulbia had completely collapsed and that a dorsal CSF space was present. Follow-up MR images provided significant information on the cervical spinal cord tethering after FMD with duraplasty for Chiari malformation. We encourage sharp surgical detethering and duraplasty with Gore-Tex to avoid retethering. Early recognition and treatment of this unusual but important complication are emphasized.     

Effects of birth advancement in Chiari malformation in a surgical myelomeningocele model in rabbits

Background/Purpose

In myelomeningocele (MMC), Chiari II malformation progresses during gestation because of the continuous loss of cerebrospinal fluid at the site of the defect. Our purpose was to assess the impact of birth advancement (BA) and prenatal corticosteroid treatment (PCT) on Chiari malformation in a surgical MMC model in rabbits.

Methods

A surgical MMC-like defect was created in 75 fetal rabbits. Animals were distributed into 4 groups depending on the treatment received: not treated and those undergoing BA + PCT, BA, or PCT. The degree of Chiari malformation in newborn rabbits was defined as the percentage of downward protrusion of the hindbrain between the end of the occipital bone and the beginning of the first vertebral arch.

Results

The degree of hindbrain herniation was 80% (8.15) in the not treated group, 36.8% (10.57) in BA + PCT, 41.8% (8.27) in BA, and 44.4% (8.32) in PCT. The BA + PCT, BA, and PCT groups showed less severe hindbrain herniation than not treated animals (mean decrease, 39.86%; SD, 10.57; P = .000). There were no significant differences between the BA + PCT, BA, and PCT groups (P = .311).

Conclusions

Birth advancement and prenatal administration of corticosteroids decrease the severity of the hindbrain herniation component of Chiari II malformation in surgical MMC in fetal rabbits.