How I do it - The "drum skin" duraplasty technique after foramen magnum decompression for Chiari malformations.

BACKGROUND: Chiari malformations are a spectrum of posterior cranial fossa anomalies characterized by herniation of the cerebellar tonsils through the foramen magnum. Surgery is the treatment of choice for selected patients with good postoperative outcomes. METHODS: We describe foramen magnum decompression (FMD) with dural opening and a "drum skin" duraplasty technique. CONCLUSIONS: In our experience, FMD with "drum skin" duraplasty is a safe and effective procedure, reducing the risk of CSF leakage and arachnoidal adhesions and yielding better long-term clinical and radiological outcomes than other traditional techniques.

Inferiorly Directed Posterior Cranial Vault Distraction for Treatment of Chiari Malformations.

OBJECTIVE: The authors present a case series of patients with Chiari I malformations treated with distraction osteogenesis of the posterior cranial vault, utilizing a vertical distraction vector for appropriate cranial vault expansion while mitigating the risks of scaphocephaly and cerebellar ptosis. PATIENTS AND METHODS: Patients with syndromic and nonsyndromic Chiari I malformations treated with vertical-vector distraction osteogenesis of the posterior cranial vault were identified from 2008 to 2014. Demographics, preoperative and postoperative clinical symptoms, and perioperative details were assessed. Long-term esthetic outcomes, complications, and symptomatic improvement were evaluated in conjunction with neurosurgery. RESULTS: Nine patients were identified. Five had known syndromes, 2 likely had unidentified syndromes, and 2 were nonsyndromic. Seven had prior Chiari-related surgeries. Most presented with hydrocephalus, motor symptoms, and developmental delay. Operatively, 2 to 3 internal distraction fixators were applied such that the vector of distraction was along a cephalad-caudad axis. Devices were activated on postoperative day 5 and distracted 1 mm per day. Three postoperative complications were found within the first 3 months which included a dislodged distraction arm, a device extrusion, and a local cellulitis. No complications affected the clinical outcome. Radiographic follow-up showed good bone formation, decompression of the posterior fossa, improved cerebrospinal fluid flow, and no cerebellar ptosis. Neurological surveillance showed improvement in intracranial pressure, hydrocephalus, motor symptoms, and behavioral problems. CONCLUSION: The authors have presented 9 patients with Chiari I malformations treated with distraction osteogenesis, along with a novel technique to safely and effectively expand the posterior fossa while minimizing the risk of cerebellar ptosis. LEVEL OF EVIDENCE: Level II (prognostic/risk studies).

Chiari type 1-a malformation or a syndrome? A critical review.

OBJECTIVE: As the understanding of pathophysiology behind Chiari malformation still is limited, the treatment of Chiari malformation type 1 remains rather empirical. This may result in suboptimal treatment strategy and outcome in many cases. In this review, we critically address whether the condition known today as Chiari malformation type I should rather be denoted Chiari syndrome. METHODS: The current knowledge of Chiari malformation type 1 is summarized from the historical, etymological, genetic, clinical, and in particular pathophysiological perspectives. RESULTS: There are several lines of evidence that Chiari malformation type 1 represents a condition significantly different from types 2 to 4. Unlike the other types, the type 1 should rather be considered a syndrome, thus supporting the reasons to reappraise the traditional classification of Chiari malformations. CONCLUSION: We propose that Chiari malformation type 1 should rather be denoted Chiari syndrome, while the notation malformation is maintained for types 2-4.

Chiari malformation type I and basilar invagination originating from atlantoaxial instability: a literature review and critical analysis.

INTRODUCTION: Recently, a novel hypothesis has been proposed concerning the origin of craniovertebral junction (CVJ) abnormalities. Commonly found in patients with these entities, atlantoaxial instability has been suspected to cause both Chiari malformation type I and basilar invagination, which renders the tried and tested surgical decompression strategy ineffective. In turn, C1-2 fusion is proposed as a single solution for all CVJ abnormalities, and a revised definition of atlantoaxial instability sees patients both with and without radiographic evidence of instability undergo fusion, instead relying on the intraoperative assessment of the atlantoaxial joints to confirm instability. METHODS: The authors conducted a comprehensive narrative review of literature and evidence covering this recently emerged hypothesis. The proposed pathomechanisms are discussed and contextualized with published literature. CONCLUSION: The existing evidence is evaluated for supporting or opposing sole posterior C1-2 fusion in patients with CVJ abnormalities and compared with reported outcomes for conventional surgical strategies such as posterior fossa decompression, occipitocervical fusion, and anterior decompression. At present, there is insufficient evidence supporting the hypothesis of atlantoaxial instability being the common progenitor for CVJ abnormalities. Abolishing tried and tested surgical procedures in favor of a single universal approach would thus be unwarranted.

Shunt dependency syndrome and acquired Chiari malformation secondary to cerebrospinal fluid diversion procedures: a 9-year longitudinal observation.

BACKGROUND: Shunt dependency syndrome is a rare long-term complication of cystoperitoneal (CP) shunting for intracranial arachnoid cysts, which is characterized by acute intracranial hypertension with normal-sized or small ventricles. Additionally, acquired Chiari type I malformations (ACIM) could be infrequently secondary to extrathecal shunt drainage of cerebrospinal fluid. CASE REPORT: We described a 12-year-old boy who developed shunt dependency syndrome following a CP shunting for treating a temporal arachnoid cyst. To manage this rare complication, we placed a lumboperitoneal (LP) shunt. During the follow-up period, shunt-induced ACIM and concomitant syringomyelia were noted. CONCLUSION: Shunt dependency syndrome is a rare complication secondary to CP shunting in the treatment of temporal arachnoid cysts, and LP shunting is an effective option to relieve the intracranial hypertension. However, the clinicians should be alert to the ACIM as a rare late complication of cerebrospinal fluid diversion procedures, and the potential protecting effect of the programmable valve should be emphasized.

Trends in incidence and long-term outcomes of myelomeningocele in British Columbia.

PURPOSE: Myelomeningocele is typically a disabling condition that results in neurologic, orthopedic, and urologic morbidity. The aim of this study was to examine the trends over time in both incidence and outcomes of myelomeningocele (MMC) in British Columbia (BC). METHODS: A retrospective chart review was performed of all children with MMC followed in the British Columbia Children's Hospital (BCCH) Spinal Cord Clinic between 1971 and 2016. The incidence of new MMC cases and the long-term outcomes of MMC were compared between two 10-year cohorts. The first cohort comprised children born with MMC between 1971 and 1981, and the second cohort comprised children born with MMC between 1996 and 2006. RESULTS: A total of 309 children with MMC were followed in the BCCH Spinal Cord Clinic between 1971 and 2016. There were 101 and 46 children with MMC in the two-time cohorts, respectively. Between the earlier and later cohorts, there was a significant difference in the following: MMC incidence [2.5/10,000 births vs 1.1/10,000 births, respectively (p = 0.0002)], mortality [18 vs 0% (p = 0.0009)], and the proportion of cases repaired in under 48 h [56 vs 98% (p < 0.0001)]. For surviving children, the proportion of children attending special classes was significantly different between the earlier and later cohorts [16 vs 46%, respectively (p = 0.0002)], whereas all other outcome measures, including the proportion with hydrocephalus, kyphoscoliosis, Chiari II surgery, bowel and bladder continence, recreation participation, obesity, and ambulation, were not significantly different. CONCLUSIONS: In BC, the incidence of new cases of MMC has decreased between 1971 and 2016, while the probability of survival for these patients has increased. Despite earlier and more universal post-natal repair, long-term outcomes have not improved significantly over time. Future research should focus on developing ways of reducing disability and improving quality of life for MMC patients and their families.

Development of profound Chiari I malformation and cerebellar tissue loss and resolution following shunting of posterior fossa extra-axial cyst. Case report.

INTRODUCTION: Chiari I malformation can be due to a multitude of etiologies such as craniosynostosis or hydrocephalus. A posterior fossa extra-axial cyst (PFEAC) appears to be an extremely rare cause of this form of hindbrain herniation. CASE REPORT: Herein, we report a case of PFEAC that presented with no Chiari I malformation and then presented months later with a significant Chiari I malformation. Following shunt placement of a PFEAC, striking reversal of the Chiari malformation as well as reconstitution of the cerebellum was noted. CONCLUSIONS: Patients with PFEAC might develop a Chiari I malformation and this might be treated with shunting of the PFEAC alone.

Delayed Presentation of Isolated Sagittal Synostosis With Raised Intracranial Pressure and Secondary Chiari Malformation With Cervical Syringomyelia.

Sagittal craniosynostosis (SC) is the most common type of premature suture fusion presenting in approximately 1 in every 5000 births with a 3:1 male:female ratio. The most common indication for surgery is the improvement of the cosmetic appearance of the skull, since a cranial deformation may have a significant psychosocial impact on affected patients. Relief from raised intracranial pressure is a further indication for surgery, although an increased intracranial pressure (ICP) can be demonstrated only in a minority of affected children at diagnosis. It is even more rare to have Chiari malformations (CMs) secondary to ICP in an isolated SC, as shown in a study by Strahle et al (Neurosurg Focus 2011;31:E2), demonstrating only 5 (3%) of the 183 with isolated sagittal synostosis having a CM. The authors present the rare case of a 4-year-old boy presenting late with raised intracranial pressure (40 mm Hg) and his management with 1 stage vault expansion and decompression of CM.

Fetal Myelomeningocele Repair through a Mini-Hysterotomy.

OBJECTIVE: To present the feasibility of fetal myelomeningocele (MMC) repair through a mini-hysterotomy and to describe the perinatal results from our initial experience. METHODS: A descriptive study of cases of fetal MMC correction via mini-hysterotomy performed between 2014 and 2016. RESULTS: Forty-five women underwent fetal surgery and 87% (39/45) delivered. A complete multilayer correction of the MMC was possible in all cases. There were no maternal, fetal or neonatal deaths. No maternal or fetal complications occurred from fetal MMC correction until maternal hospital discharge. The average gestational age (GA) at surgery was 24.5 weeks (standard deviation, SD: 1.7; range: 20.7-26.9). The median hysterotomy length was 3.05 cm (SD: 0.39; range: 2.50-3.50). One patient (1/39; 2.6%) experienced chorioamniotic separation. Nine patients (9/39; 23.1%) had premature preterm rupture of membranes at a median GA of 34.1 weeks (range: 31.1-36.0). The average GA at delivery was 35.3 weeks (SD: 2.2; range: 27.9-39.1). Ninety-five percent (37/39) of our patients had an intact hysterotomy site at delivery. Ventriculoperitoneal shunt placement was necessary for 7.7% (3/39) of the neonates. CONCLUSION: Fetal MMC repair is feasible through a mini-hysterotomy. This approach appears to be associated with reduced risks of very preterm delivery and maternal, fetal and neonatal complications.

Cerebrospinal fluid leakage and Chiari I malformation with Gorham's disease of the skull base: A case report.

BACKGROUND: Gorham's syndrome is a rare bone disorder characterized by massive osteolysis of unknown etiology. There are no reports of comorbidity involving cerebrospinal fluid (CSF) leakage and Chiari I malformation with Gorham's syndrome. Here, we report an unusual case of an acute presyrinx state complicated by bacterial meningitis due to CSF leakage and Chiari I malformation associated with Gorham's disease of the skull base. CASE PRESENTATION: A 25-year-old woman with Chiari I malformation associated with Gorham's syndrome presented with aggressive paresthesia following bacterial meningitis. Axial magnetic resonance imaging (MRI) and computed tomography (CT) cisternography revealed CSF leakage in the right petrous apex. A presyrinx state was diagnosed based on the clinical symptoms and MRI findings. With resolution of the bacterial meningitis, the spinal edema and tonsillar ectopia also improved. Surgical repair of the CSF leakage was performed by an endoscopic endonasal transsphenoidal approach to prevent recurrence of meningitis. The postoperative course was uneventful. CONCLUSION: Skull base osteolysis in Gorham's syndrome may induce Chiari I malformation and CSF leakage. We should pay attention to acute progression of clinical symptoms because Gorham's syndrome may predispose to development of Chiari I malformation and may be complicated by CSF leakage.

Cryopreserved human umbilical cord patch for in-utero spina bifida repair.

OBJECTIVE: To identify a patch system to repair surgically created spina bifida in a sheep model for its efficacy in healing the skin defect, protecting the underlying spinal cord and reducing the Chiari II malformation. METHODS: Spina bifida was created surgically in 16 fetuses from eight timed-pregnant sheep at gestational age of 75 days. Two fetuses did not survive the procedure. Repeat hysterotomy was performed at 95 days' gestation to cover the defect with either biocellulose film with underwater adhesive (BCF-adhesive) (n = 7) or human umbilical cord with suture (HUC-suture) (n = 7). Three fetuses without formation of the defect served as reference controls. The skin healing was examined by direct visualization after a planned Cesarean section at term, followed by histological analysis using hematoxylin and eosin and Masson's trichrome stains. Mid-sagittal sections of the fetal cranium and upper cervical spine were analyzed by a pediatric neuroradiologist who was blinded to the type of patch received. RESULTS: Three fetuses that received the BCF-adhesive and six fetuses that received the HUC-suture survived to term for final analysis. As a result of dislodgment of the BCF-adhesive, all spina bifida defects repaired using BCF-adhesive were not healed and showed exposed spinal cord with leakage of cerebrospinal fluid. In contrast, all spinal defects repaired by HUC-suture were healed with complete regrowth of epidermal, dermal and subdermal tissue components, with no exposed spinal cord. The maximal skin wound width was 21 ± 3.6 mm in the BCF-adhesive group but 3 ± 0.8 mm in the HUC-suture group (P < 0.001). The spinal cord area (P = 0.001) and the number of anterior horn cells (P = 0.03) was preserved to a greater degree in the HUC-suture group than in the BCF-adhesive group, whilst psammoma bodies, signifying neuronal degeneration, were only observed in the BCF-adhesive group. Anatomic changes, indicative of Chiari II malformation, were seen in all three fetuses of the BCF-adhesive group but in none of the HUC-suture group (P < 0.01). CONCLUSION: Cryopreserved umbilical cord graft is a promising regenerative patch for intrauterine repair of spina bifida.

A novel technique to treat acquired Chiari I malformation after supratentorial shunting.

PURPOSE: The acquired Chiari I malformation with abnormal cranial vault thickening is a rare late complication of supratentorial shunting. It poses a difficult clinical problem, and there is debate about the optimal surgical strategy. Some authors advocate supratentorial skull enlarging procedures while others prefer a normal Chiari decompression consisting of a suboccipital craniectomy, with or without C1 laminectomy and dural patch grafting. METHODS: We illustrate three cases of symptomatic acquired Chiari I malformation due to inward cranial vault thickening. RESULTS: We describe a new surgical approach that appears to be effective in these patients. This approach includes the standard Chiari decompression combined with posterior fossa augmentation by thinning the occipital planum. CONCLUSION: Internal volume re-expansion of the posterior fossa by thinning the occipital planum appears to be an effective novel surgical strategy in conjunction with the standard surgical therapy of Chiari decompression.

Sequential morphological change of Chiari malformation type II following surgical repair of myelomeningocele.

PURPOSE: To document long-term morphological changes of Chiari type II malformation (CM-II) following closure of spina bifida manifesta (SBM). METHODS: We retrospectively evaluated postnatal magnetic resonance images of the CM-II and posterior fossa (PF) in 28 consecutive cases. We measured changes in vertebral level and length of the cerebellar peg (CP), cerebrospinal fluid (CSF) spaces anterior and posterior to the cerebrospinal junction, PF area, and the anteroposterior diameters of the foramen magnum (FM) and C1 vertebra. We examined the morphological differences between the cases with and without ventriculoperitoneal (VP) shunting and derived predicted means by nonlinear mixed-effect modeling. RESULTS: At birth, there were significant differences in CP length, PF area, and FM and C1 diameters between those who underwent VP shunting and those who did not. In cases with a CP below C1, VP shunting was required in every case but one. In those with visible CSF space at birth, VP shunts were not required. In 17 of 18 cases with a CP below C1, the vertebral level ascended by mean two vertebral levels (range 0-5 levels) within 4-6 months of delivery. In the remaining case, slowly progressive hydrocephalus and delayed CP descent required VP shunting at 8 months. Predicted mean CP length and FM and C1 diameters were greater in those who underwent VP shunting, but there was no difference in predicted mean PF area. CONCLUSION: The morphology of CM-II and the presence of hydrocephalus influence each other in children who have undergone postnatal SBM repair.

Sudden onset of Chiari malformation type 1 in a young child after trauma.

INTRODUCTION: Chiari 1 malformation is a rare craniovertebral junction malformation accounting up to 1 case in every 1000 newborns per year. It is characterized by herniation of cerebellar tonsils below the foramen magnum sometimes with syringomyelia. Usually, patients have a long history of slowly progressive neurological symptoms. Uncommonly, Chiari 1 malformation could present with a sudden onset, also after trauma. Few cases are reported about young children. METHODS: The authors report a case of a 6-month child with symptoms at onset after a mild trauma. The pertinent literature is reviewed. CONCLUSIONS: Symptoms of Chiari 1 malformation are usually slowly progressive. Few cases have been reported of the sudden onset of symptoms, some of these after trauma. In young children, the clinical setting could be insidious and potentially lethal. A sudden onset of Chiari 1 malformation must be considered as a consequence of trauma, usually after performing a brain MRI. Management of these cases is still controversial, and surgery may be indicated in managing symptoms; however, it seems to not affect clinical outcome.

Chiari III malformation: a comprehensive review of this enigmatic anomaly.

INTRODUCTION: Chiari III is one of the rarest of the Chiari malformations and is characterized by a high cervical or low occipital encephalocele and osseous defect with or without spinal cord involvement and may include many of the anatomical characteristics seen in the Chiari II malformation. Herein, we provide a comprehensive review of this rare anomaly as well as a translation of Chiari's original description. METHODS: We review all reported cases of Chiari III malformation found in the extant literature. CONCLUSIONS: Out of 57 reported cases of Chiari III malformation, encephaloceles were in a high cervical/low occipital position in 23, 8 were in a high cervical position, 17 were in low occipital position, and the position in 9 cases was not reported. The pathogenesis of Chiari III malformation remains unclear. The majority of patients have concomitant hydrocephalus. Brain parts occurring in the sac from the most to least common include the following: cerebellum, occipital lobe, and parietal lobe. The severity of symptoms is correlated with the amount of brain structures within the encephalocele. Neurologic functional outcomes have been varied and depend on the neurological status of the patient before surgery.

The Chiari malformations: a review with emphasis on anatomical traits.

Hindbrain herniations come in many forms and have been further subdivided as their original descriptions. For cerebellar tonsillar ectopia, they can be divided into two categories, acquired and congenital. Acquired hindbrain herniations are due to increased intracranial pressure caused by certain conditions such as trauma or brain tumor. Although the mechanism for their formation is not clear, congenital hindbrain herniation makes up the majority of these congenital malformations. Furthermore, these malformations are often found to harbor additional anatomical derailments in addition to the hindbrain herniation whether it be the cerebellar tonsils (Chiari I malformation) or the cerebellar vermis (Chiari II malformation). This article reviews these forms of cerebellar ectopia and describes the details of their anomalous anatomy. Moreover, this article compares and contrasts the differing embryological theories found in this literature.

Relationship between pharyngitis and peri-odontoid pannus: A new etiology for some Chiari I malformations?

The pathophysiology underlying Chiari I malformations (CIMs) provides room for debate with several theories attempting to address this issue. We retrospectively reviewed many of our past patients with pediatric CIMs (specifically, those with peri-odontoid pannus), and present a hypothesis for the development of the malformation in some of said patients. Our experience with the pediatric CIM has shown that almost 1 in 20 patients who present with symptoms is found to have a peri-odontoid pannus. These masses ranged in size from 4 to 11 mm in diameter. Forty percent had a history of clinically significant pharyngitis or pharyngeal abscess. Pannus formation around the dens (odontoid) resulted in ventral compression of the craniocervical junction in each of these patients. Highlighting the hypermobility that causes such lesions, following fusion, the pannus and symptoms in several patients were diminished. Impairment of normal cerebrospinal fluid circulation out of the fourth ventricle and across the craniocervical junction appears to be a plausible endpoint in this discussion and a suitable explanation for some patients with CIM. Still, the mechanisms by which cerebrospinal fluid circulation is compromised may be variable and are not well understood. This is the first study dedicated to the evaluation of pannus formation in the CIM population. We hypothesize that pharyngeal inflammatory conditions contribute to the formation and progression of hindbrain herniation in a small subset of patients with CIMs.

Limits of the surgically induced model of myelomeningocele in the fetal sheep.

PURPOSE: The prevention of Chiari type II malformation (CM) is commonly used as a primary outcome for the evaluation of techniques of fetal myelomeningocele (MMC) surgery in the fetal lamb. The aim of our study was to investigate the frequency of the associated CM in the MMC fetal sheep model and to investigate the contribution of prenatal ultrasound evaluation of CM at the time of prenatal repair. METHODS: A MMC-like lesion was surgically created at 75 days of gestation in 21 fetuses performing a L1-L5 laminectomy followed by an excision of the exposed dura and a midline myelotomy. At a 90-day gestation, among the 19 alived fetuses, a conventional repair of the MMC-like lesion was performed in seven, four of whom underwent cerebral ultrasound (US) examination before the repair. Twelve fetuses remained untreated (control group). All fetuses underwent post-mortem examination (PM) at 138 days. RESULTS: At a 90-day gestation, CM was demonstrated by US examination in all four evaluated fetuses. At birth, CM was found in 3/6 control whether CM was absent in all alived fetuses in the prenatal repair group (n = 4). CONCLUSIONS: Creation of a MMC-like lesion with an additional myelotomy does not always lead to hindbrain herniation. Our study suggests that CM should be assessed by ultrasound examination at the time of the prenatal repair to demonstrate the effectiveness of new techniques for the prenatal repair of MMC.