Atlantoaxial Fixation for Basilar Invagination without Obvious Atlantoaxial Instability (Group B Basilar Invagination): Outcome Analysis of 63 Surgically Treated Cases.

BACKGROUND: We discuss the rationale of surgical treatment of group B basilar invagination by atlantoaxial facet joint stabilization and segmental arthrodesis. METHODS: From January 2010 to April 2016, 63 patients with group B basilar invagination were surgically treated. All patients had varying degree of myelopathy-related functional disability. Fifty-two patients had both Chiari malformation and syringomyelia. All patients were treated by atlantoaxial plate and screw fixation with the techniques described by us in 1994 and 2004. Foramen magnum decompression or syrinx manipulation was not carried out in any patient. Occipital bone and subaxial spinal elements were not included in the fixation construct. RESULTS: Three patients died in the immediate postoperative phase. In the remaining patients, there was clinical improvement and no patient's neurologic function worsened after surgery. In 12 of 38 patients in whom postoperative magnetic resonance imaging was possible, at a follow-up of at least 3 months, there was reduction in the size of the syrinx. CONCLUSIONS: The pathogenesis of basilar invagination in group B is related to atlantoaxial instability. The clinical outcome suggests that the surgical treatment in these cases should be directed toward atlantoaxial stabilization and aimed at segmental arthrodesis. Inclusion of the occipital bone in the fixation construct is not necessary. Foramen magnum decompression and procedures involving manipulation of Chiari malformation and syringomyelia are not necessary.

A Systematic Review of Chiari I Malformation: Techniques and Outcomes.

OBJECTIVE: To elucidate the most efficacious treatments of Chiari I malformation (CIM). METHODS: A literature search was performed using PubMed, CINAHL/Ovid, Cochrane library, and the Elsevier database. The key words "Chiari I malformation," "Chiari malformation type I," "surgery," and "treatment" were used for the search. Articles had to be peer reviewed and provide primary outcomes measured by clinical and radiographic outcomes after surgical treatments. Exclusion criteria included non-English-language articles, case reports, commentaries, information from textbooks and expert opinions, and articles that did not provide outcomes concerning specific surgical methods. Patients included were classified into 4 groups according the procedure: only bony decompression but not duroplasty (group I), bony decompression plus duroplasty (group II), bony decompression plus the resection of tonsils (group III), and shunt (group IV). RESULTS: Eighteen studies were identified. Groups II and III had a significantly higher improvement rate (82.25%, 86.10%, P < 0.05) of outcomes with regard to clinical signs and symptoms than the other groups. Group IV showed a statistically higher rate (30.49%, P < 0.05) of aggregating clinical signs and symptoms. In patients with syringomyelia, group III showed better clinical improvement (96.08%). Group II displayed a significantly higher rate of decrease in the size of cavities (83.33%, P < 0.05). Group IV had a statistically higher rate of increase in the size of cavities (33.87%, P < 0.05). CONCLUSIONS: Only bony decompression cannot achieve satisfactory outcomes. Bony decompression plus duroplasty showed the most favorable outcomes. Resection of tonsils was not recommended because of the high rate of side effects. Shunt may aggregate clinical signs and symptoms and increase the size of cavities.

Surgical treatment of Chiari I malformation--analysis of intraoperative findings, complications, and outcome for 371 foramen magnum decompressions.

BACKGROUND: Foramen magnum decompression is widely accepted as the treatment of choice for Chiari I malformation. However, important surgical details of the procedure are controversial. OBJECTIVE: This study analyzes 371 decompressions focusing on intraoperative findings, analysis of complications, and long-term outcomes. METHODS: Among 644 patients between 1985 and 2010, 359 patients underwent 371 decompressions. Surgery for symptomatic patients consisted of suboccipital craniectomy, C1 laminectomy, arachnoid dissection, and duraplasty. Short-term results were determined after 3 months; long-term outcomes were evaluated with Kaplan-Meier statistics. RESULTS: The mean age was 40 ± 16 years; mean follow-up was 49 ± 56 months; 75.8% demonstrated syringomyelia. The complication rate was 21.8% with permanent surgical morbidity of 3.2% and surgical mortality of 1.3%. Of the patients, 73.6% reported improvement after 3 months; 21% were unchanged. Overall, 14.3% demonstrated a neurological deterioration within 5 years and 15.4% within 10 years. The severity of neurological symptoms correlated with the grade of arachnoid pathology. Outcome data correlated with the number of previous decompressions, severity of arachnoid pathology, handling of the arachnoid, type of duraplasty, and surgical experience. First-time decompressions with arachnoid dissection and an alloplastic duraplasty resulted in surgical morbidity for 2.0%, a 0.9% mortality rate, postoperative improvement after 3 months for 82%, and neurological recurrence rates of 7% after 5 years and 8.7% after 10 years. CONCLUSION: Arachnoid pathology in Chiari I malformation has an impact on clinical symptoms and postoperative results. Decompressions with arachnoid dissection and an alloplastic duraplasty performed by surgeons experienced with this pathology offer a favorable long-term prognosis.

Fetal endoscopic myelomeningocele closure preserves segmental neurological function.

AIM: Our aim was to compare the effect of prenatal endoscopic with postnatal myelomeningocele closure (fetally operated spina bifida aperta [fSBA]) versus neonatally operated spina bifida aperta [nSBA]) on segmental neurological leg condition. METHOD: Between 2003 and 2009, the fetal surgical team (Department of Obstetrics, University of Bonn, Germany) performed 19 fetal endoscopic procedures. Three procedures resulted in fetal death, three procedures were interrupted by iatrogenic hemorrhages and 13 procedures were successful. We matched each successfully treated fSBA infant with another nSBA infant of the same age and level of lesion, resulting in 13 matched pairs (mean age 14 mo; SD 16 mo; f/m=1.6; female-16, male-10). Matched fSBA and nSBA pairs were compared in terms of segmental neurological function and leg muscle ultrasound density (MUD). We also determined intraindividual difference in MUD (dMUD) between myotomes caudal and cranial to the myelomeningocele (reflecting neuromuscular damage by the myelomeningocele) and compared dMUD between fSBA and nSBA infants. Finally, we correlated dMUD with segmental neurological function. RESULTS: We found that, on average, the fSBA group were born at a lower gestational age than the nSBA group (median 32 wks [range 25-34 wks] vs 39 wks [34-41 wks]; p=0.001) and experienced more complications (chorioamnionitis, premature rupture of the amniotic membranes, oligohydramnios, and infant respiratory distress syndrome necessitating intermittent positive-pressure ventilation). Neurological function was better preserved after fSBA than after nSBA (median motor and sensory gain of two segments; better preserved knee-jerk [p=0.006] and anal [p=0.032] reflexes). The dMUD was smaller in fSBA than in nSBA infants (mean difference 24, 95% confidence interval [CI] 15-33; p<0.05), which was associated with better preserved segmental muscle function. INTERPRETATION: Fetal endoscopic surgery is associated with spinal segmental neuroprotection, but it results in more complications. Before considering clinical implementation of fetal endoscopic myelomeningocele closure as standard care, the frequency of complications should be appropriately reduced and results assessed in larger groups over a longer period of time.

Stridor at birth predicts poor outcome in neonates with myelomeningocele.

BACKGROUND: Stridor, associated with vocal cord paralysis, in neonates with myelomeningocele (MMC) is a recognized symptom related to Chiari II malformation (CM). In most children, stridor appears after birth. Control of hydrocephalus, if present, and urgent decompression of the CM are recommended for treatment of these patients. Such management typically improves symptoms. Occasionally, stridor is present at birth and may be secondary, in part, to maldevelopment or prenatal ischemia of the brain stem, rather than treatable compression. There is minimal literature describing the outcome after Chiari decompression in this population. The purpose of this study was to review the outcomes of neonates with MMC and stridor at birth and compare it to MMC patients who develop stridor later. We hypothesized that unlike stridor which develops after birth, stridor at birth predicts a dismal outcome, despite aggressive surgical treatment. METHODS: Retrospective review of newborns with MMC and CM was performed in our institution from 1975 to 2010. Patients with stridor at birth and those who developed stridor later in infancy were identified. Outcomes were analyzed. Autopsy findings were reviewed when available. RESULTS: Six patients with MMC who presented with stridor at birth were identified. Five of these patients had decompression of CM and treatment of hydrocephalus, if present, within the first 2 weeks of life. All patients died: three within 1 month and the oldest at 62 months. In the three patients with autopsies, vernix caseosa meningitis was present. Eight patients presented with stridor later in infancy. CM decompression was performed in seven of them. One patient out of the seven with late onset of stridor died at 13 months after CM surgery. The mortality rate after CM decompression was worse in patients with stridor at birth than those presenting later with stridor (chi-square p = 0.015). CONCLUSIONS: In newborns with MMC, stridor at birth may predict dismal outcome despite CM decompression. Unlike the situation in neonates who develop stridor after birth, the outcome in those presenting with stridor at birth does not seem to be impacted by decompression of the CM. Nonoperative management may be an option to offer in this population. Additionally, vernix caseosa meningitis may contribute to the severe irreversible brain stem dysfunction in these newborns.

Correlation of hindbrain CSF flow and outcome after surgical decompression for Chiari I malformation.

OBJECTIVE: Many patients with symptomatic Chiari I malformation experience symptom recurrence after surgical decompression. Improved radiographic predictors of outcome are needed to better select patients most likely to benefit from surgical intervention. We examined whether ventral or dorsal cerebrospinal fluid (CSF) flow dynamics assessed by cine phase-contrast MRI scans could predict response to posterior fossa decompression for Chiari I malformation. METHODS: Forty-four consecutive pediatric patients undergoing pre-operative cine phase-contrast MRI followed by posterior fossa decompression for Chiari I malformation were retrospectively reviewed. The association of pre-operative ventral or dorsal CSF flow abnormalities at the foramen magnum with symptom-free survival after surgical decompression was assessed via Kaplan-Meier plots and log-rank analysis. RESULTS: Mean +/- SD age at time of surgery was 8 +/- 6 years. Sixteen (36%) patients demonstrated decreased CSF flow dorsal to the cervico-medullary brainstem alone. Fourteen (32%) patients demonstrated abnormal CSF flow both ventral and dorsal to the cervico-medullary brainstem. Fourteen (32%) had normal hindbrain CSF flow. Overall, 13 (30%) patients experienced some degree of symptom recurrence by last follow-up (mean of 27 +/- 16 months post-operatively). Symptom recurrence did not differ as a function of degree of tonsilar ectopia (p = 0.55). Abnormal CSF flow dorsal to the cervico-medullary brainstem was not associated with symptom recurrence after surgical decompression (p = 0.10). However, combined pre-operative ventral and dorsal CSF flow abnormality was associated with a significant reduction (2.6-fold) in the risk of post-operative symptom recurrence (p < 0.05). Only one patient (7%) with pre-operative ventral and dorsal CSF flow pathology experienced symptom recurrence 3.5 years after surgery versus 12 (40%) patients without ventral CSF flow pathology. There were otherwise no differences in baseline clinical, radiological, or operative variables between patients with abnormal versus normal ventral CSF flow. CONCLUSION: The presence of decreased CSF flow both ventral and dorsal to the cervico-medullary brainstem was associated with improved response to hindbrain decompression for Chiari I malformation in children. Cine phase-contrast MRI may be a useful tool for surgical risk stratification and identifying patients that may be optimal surgical candidates. Combined ventral and dorsal hindbrain CSF flow pathology may better predict response to posterior fossa decompression compared to dorsal CSF flow pathology alone.

Chiari-like malformation with syringomyelia in the Cavalier King Charles spaniel: long-term outcome after surgical management.

OBJECTIVE: To evaluate long-term success of cranial cervical decompression for management of canine Chiari-like malformation with syringomyelia (CM/SM). STUDY DESIGN: Retrospective clinical study. ANIMALS: Cavalier King Charles spaniels (n=15). METHODS: After diagnosis by magnetic resonance imaging (MRI) dogs had cranial cervical decompression with durotomy. Seven dogs had the durotomy patched with biocompatible collagen matrix. Clinical outcome was monitored for >12 months. RESULTS: All dogs either improved (80%) or were unchanged (20%) postoperatively. Postoperative MRI in 6 dogs revealed persistence of syringomyelia. Seven dogs (47%) subsequently deteriorated, 0.2-2.3 years after surgery (mean, 1.3 years) and 2 dogs were eventually euthanatized as a consequence. Twelve dogs were still alive, 1-6.5 years after surgery (mean, 2.5 years). CONCLUSION: Cranial cervical decompression surgery is associated with low mortality and morbidity, and results in clinical improvement in most dogs. The procedure seemingly does not result in syrinx collapse and resolution. Clinical improvement may not be sustained and some dogs can be expected to deteriorate. CLINICAL RELEVANCE: Cranial cervical decompression surgery may have a role in management of CM/SM. In dogs with severe pain, it can improve quality of life for several years; however, it does not appear to adequately address the primary cause of syringomyelia. Further prospective study is needed to better understand the pathogenesis and treatment of this disorder. Because this condition causes neuropathic pain but does not necessarily result in euthanasia more information is needed on appropriate pain management for these patients.

[Acute respiratory failure as the sol inaugural sign of Arnold-Chiari malformation. Two cases]. / Insuffisance respiratoire aiguë isolée révélant une malformation d'Arnold-Chiari.

Arnold-Chiari malformation is an occipitocervical malformation where the cerebellar amygdales descend below the occipital foramen. Acute respiratory failure is an exceptional inaugural sign. We report two cases disclosed by alveolar hypoventilation associated with type I Arnold-Chiari malformation. The two patients age 51 and 52 years had an uneventful past history and presented with hypercapnic encephalopathy with acute respiratory failure requiring ventilatory assistance. Respiratory function tests, helicoidal thoracic computed tomographic angiography, electromyogram, cardiac echography, and thyroid and immunological tests were normal. Blood gases and polysomnography were in favor of central hypoventilation without sleep apnea. Magnetic resonance imaging demonstrated type I Arnold-Chiari malformation. The course was complicated by recurrent respiratory failure in both patients. Surgical decompression performed for the first patient provided no improvement. This patient died two months after surgery subsequent to aspiration pneumonia. The second patient was treated with continuous positive pressure noninvasive ventilatory assistance and had a good outcome at 25 months. These two cases illustrate the absence of any neurological sign, acute respiratory failure being the only sign of Arnold-Chiari malformation.

"Conservative" cranio-cervical decompression in the treatment of syringomyelia-Chiari I complex. A prospective study of 20 adult cases.

STUDY DESIGN: This study was designed to investigate prospectively a series of patients with syringomyelia-Chiari I complex operated on by a minimally invasive procedure. OBJECTIVE: The objective was to determine whether a relatively simple and low-risk osteo-dural decompression would obtain as good clinico-radiological results as those observed after the commonly used, more complex posterior fossa surgery. SUMMARY OF BACKGROUND DATA: The majority of hypotheses concerning the pathogenesis of syringomyelia link it to the existence of some derangement of the cerebro-spinal fluid flow at the cranio-spinal level and, consequently, surgical procedures are directed toward decompressing the cranio-cervical junction; however, there is no clear-cut evidence that simple osteo-dural decompression should be associated with manipulation of nervous tissue for the purpose of restoring to normal an altered cerebro-spinal fluid flow dynamic. METHODS: The procedure consisted of a small suboccipital craniectomy and laminectomy of C1 (when necessary C2 as well), followed by dura mater opening. Exploration and plugging of the obex, resection of arachnoid adherences, or amputation of the amygdala(e) were never performed. Every effort was made to keep the arachnoid intact. The series included 20 patients with progressive disease treated according the above-mentioned criteria. RESULTS: Mortality and morbidity were nil and MRI controls showed shrinkage of the syrinx in all cases. At long-term follow-up (average, 2.4 years), 8 patients were considered improved, 11 stabilized, and 1 patient continued to deteriorate despite the collapse of the cord cavity. CONCLUSION: Considering that the results of this "conservative" cranio-cervical decompression are at least comparable to those obtained with other surgical procedures, this procedure, which was not associated with mortality or morbidity, currently should be considered the first option in the treatment of syringomyelia-Chiari I complex.