Posterior Fossa Decompression For Chiari Research Articles

Long-term outcomes following posterior fossa decompression in pediatric patients with Chiari malformation type 1, a population-based cohort study

Abstract Objective Posterior fossa decompression for Chiari malformation type I (Chiari 1) is effective and associated with a low risk of complication. However, up to 20% of patients may experience continued deficits or recurring symptoms after surgical intervention. For pediatric patients, there are no established tools to predict outcomes, and the risk factors for unfavorable postoperative outcomes are poorly understood. Hence, our aim was to investigate baseline data and early postoperative predictors of poor outcomes as determined by the Chicago Chiari outcome scale (CCOS). Methods All pediatric patients (< 18 years) receiving a posterior fossa decompression for Chiari 1 between the years of 2005 and 2020 at the study center were eligible for inclusion. Patients with congenital anomalies were excluded. Results Seventy-one pediatric patients with a median age of 9 years were included. Most patients (58%) were females. Chiari 1 was associated with syringomyelia (51%), scoliosis (37%), and hydrocephalus (7%). Perioperative complications occurred in 13 patients (18%) of which two required additional procedures under general anesthesia. On multivariable proportional odds logistic regression, motor deficits (OR: 0.09; CI95%: [0.01–0.62]; p = 0.015), and surgical complications (OR: 0.16; CI95%: [0.41–0.66]; p = 0.011) were significant predictors of worse outcomes. The presence of syringomyelia was identified as a predictor of better outcomes (OR: 4.42 CI95% [1.02–19.35]; p = 0.048). A persistent hydrocephalus during the early postoperative period after posterior fossa decompression was a strong predictor of worse long-term CCOS (OR: 0.026; CI95%: [0.002–0.328]; p = 0.005). Conclusion Results from this study indicate that the existence of motor deficits and syringomyelia prior to surgery, and surgical complications and persistent hydrocephalus despite posterior fossa decompression, were useful predictors of long-term outcome.

Patient and operative factors associated with unanticipated intensive care admission and outcomes following posterior fossa decompressions in children: A retrospective study.

IntroductionPosterior fossa decompression for Chiari I Malformation is a common pediatric neurosurgical procedure. We sought to identify the impact of anesthesia‐related intraoperative complications on unanticipated admission to the intensive care unit and outcomes following posterior fossa decompression.MethodsMedical records of all patients <18 years who underwent surgery for Chiari I malformation between 1/1/09 and 1/31/21 at the Ann & Robert H. Lurie Children's Hospital of Chicago were included. Records were reviewed for patient characteristics, anesthesia‐related intraoperative complications, postoperative complications, and surgical outcomes. The primary outcome was the incidence of unanticipated admission to the intensive care unit, and the primary variable of interest was an anesthesia‐related intraoperative complication. Patient, surgical characteristics, and year of surgery were also compared between patients with and without an unanticipated admission to the intensive care unit, and a multi‐variable adjusted estimate of odds of unanticipated admission to the intensive care unit admission following an anesthesia‐related intraoperative complication was performed. Secondary outcomes included anesthesia factors associated with an anesthesia‐related intraoperative event, and postoperative complications and surgical outcomes between patients admitted to the intensive care unit and those who were not.ResultsTwo hundred ninety‐six patients with Chiari I Malformation were identified. Clinical characteristics associated with an unanticipated admission to the intensive care unit were younger age, American Society of Anesthesiologist (ASA) physical status >2 and an anesthesia‐related intraoperative complication. 29 anesthesia‐related intraoperative complications were observed in 25 patients (8.4%). Two of 25 patients (8%) with an anesthesia‐related intraoperative complication compared with 3 of 271 (1%) patients without anesthesia‐related intraoperative complication had an unanticipated admission to the intensive care unit, odds ratio 7.8 (95% CI 1.2–48.8, p = .010). When adjusted for age, sex, ASA physical status, presenting symptoms, concomitant syringomyelia, previous decompression surgery and year of surgery, the odds ratio for an unanticipated admission to the intensive care unit following an anesthesia‐related intraoperative complication was 5.9 (95% CI 0.51–59.6, p = .149). There were no differences in surgical outcomes between patients with or without an unanticipated admission to the intensive care unit.ConclusionOur study demonstrates that although anesthesia‐related intraoperative complications during posterior fossa decompression are infrequent, they are associated with an increased risk of an unanticipated admission to the intensive care unit.

Changes in cerebrospinal fluid flow assessed using intraoperative MRI during posterior fossa decompression for Chiari malformation.

OBJECT The authors completed a prospective, institutional review board-approved study using intraoperative MRI (iMRI) in patients undergoing posterior fossa decompression (PFD) for Chiari I malformation. The purpose of the study was to examine the utility of iMRI in determining when an adequate decompression had been performed. METHODS Patients with symptomatic Chiari I malformations with imaging findings of obstruction of the CSF space at the foramen magnum, with or without syringomyelia, were considered candidates for surgery. All patients underwent complete T1, T2, and cine MRI studies in the supine position preoperatively as a baseline. After the patient was placed prone with the neck flexed in position for surgery, iMRI was performed. The patient then underwent a bone decompression of the foramen magnum and arch of C-1, and the MRI was repeated. If obstruction was still present, then in a stepwise fashion the patient underwent dural splitting, duraplasty, and coagulation of the tonsils, with an iMRI study performed after each step guiding the decision to proceed further. RESULTS Eighteen patients underwent PFD for Chiari I malformations between November 2011 and February 2013; 15 prone preincision iMRIs were performed. Fourteen of these patients (93%) demonstrated significant improvement of CSF flow through the foramen magnum dorsal to the tonsils with positioning only. This improvement was so notable that changes in CSF flow as a result of the bone decompression were difficult to discern. CONCLUSIONS The authors observed significant CSF flow changes when simply positioning the patient for surgery. These results put into question intraoperative flow assessments that suggest adequate decompression by PFD, whether by iMRI or intraoperative ultrasound. The use of intraoperative imaging during PFD for Chiari I malformation, whether by ultrasound or iMRI, is limited by CSF flow dynamics across the foramen magnum that change significantly when the patient is positioned for surgery.

Surgical results of arachnoid-preserving posterior fossa decompression for Chiari I malformation with associated syringomyelia

We analyzed the outcome of posterior fossa decompression accompanied by widening of the cisterna magna, without disturbing the arachnoid, in patients with Chiari I malformation (CMI) associated with syringomyelia. Twenty-five adult patients with CMI and syringomyelia, who underwent surgery between October 2000 and December 2008, were enrolled in this study. All patients underwent foramen magnum decompression with C1 decompression, with or without C2 decompression. Three surgeons performed a dura opening with duraplasty in 20 patients, and another surgeon excised the outer layer of the dura without duraplasty in five patients. Clinical and radiological assessments were performed preoperatively and during the follow-up period. After surgery, 20 (80%) patients achieved a significant improvement in their clinical symptoms. However, four patients (16%) achieved only a stable state, and one patient’s symptoms worsened. Radiological analysis showed that 17 patients (68%) had a favorable result; that is, a total collapse, or a marked reduction, of the syrinx. Seven patients (28%) were stable in terms of syrinx size. However, the syrinx enlarged in one patient who had undergone excision of the outer dura. Twenty-four patients achieved a widened cisterna magna with ascent of the cerebellar tonsils into the posterior fossa and acquisition of a more rounded shape. Postoperative complications included a transient headache and vomiting in three patients and transient motor weakness in one patient. Two patients developed a superficial wound infection. This study shows that arachnoid-preserving posterior fossa decompression is a safe and effective treatment for patients with CMI with associated syringomyelia.

Comment to the paper “Posterior fossa decompression and the cerebellum in Chiari type II malformation: A preliminary MRI study”

Set of Chiari malformations, per se, comprise an ensemble of interesting clinical forms, which are sometimes totally different from each other in regard to the clinical symptoms and accompanying pathological conditions of the central nervous system. Embryological background and development stages still require further explanations. There is still no single treatment mode that is widely accepted. Although most of the neurosurgeons accept early surgical correction for the symptomatic cases, treatment modality for nonsymptomatic cases is still under debate. Chiari type I and type I.5 cases are totally different story [1, 2]. The authors propose posterior fossa decompression in early infancy to prevent atrophy of cerebellum and other related posterior fossa structures in Chiari type II malformations. They calculated volumes of various structures in posterior fossa and came to a conclusion that cerebellar atrophy takes place in utero, and decompressive attempts do not help preventing cerebellar atrophy. However, they found that posterior fossa cerebrospinal fluid (CSF) volume improves and reaches to almost normal values after posterior fossa decompression as compared to normal individuals. In a recent investigation [3], total cerebellar volume was found to be significantly reduced in spina bifida myelomeningocele group as compared to the normal individuals. The results of this investigation coincide with the observations of the group, who proposes posterior fossa decompression in early infancy. The main question that suddenly rises in the mind is, while this posterior fossa decompression relieves the structures in the posterior fossa and causes an increase in CSF volume in Chiari type II cases, could this approach has any help to hydrocephalus in these patients, which is commonly attributed to the jam at foramen magnum level. The authors have found no improvement in cerebellar atrophy after decompressive surgery. On the other hand, this investigation showed that CSF volume (space as well) is augmented by posterior fossa decompression. The aim of all decompressive surgical attempts at posterior fossa is to relieve the level of foramen magnum and provide appropriate circulation of CSF for improvement of syringomyelia and brain stem compression. Although this kind of surgical approaches need more accumulated data related to the similar cases, in order to prevent forthcoming syringomyelia, to establish appropriate CSF circulation at level of foramen magnum, and to prevent brain stem compression, which can lead to lethal complications, this procedure may be helpful for the future prognosis of the patients. After the myelomeningocele operation, the timing of the posterior fossa decompression for Chiari II patients is another question to be answered as well.

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

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. 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. 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. 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.

Relationship of Cine Phase-Contrastmri to Outcome After Decompressionfor Chiari I Malformation

Many patients with symptomatic Chiari I malformations experience symptom recurrence after surgical decompression. Identification of predictors of outcome is needed to better select patients most likely to benefit from surgical intervention. We examined whether or not cerebrospinal fluid (CSF) flow dynamics assessed by cine phase contrast magnetic resonance imaging could independently predict response to posterior fossa decompression for Chiari I malformations. Pre- and postoperative CSF flow dynamics were assessed by cine phase-contrast magnetic resonance imaging in 130 consecutive patients receiving posterior fossa decompression for a Chiari I malformation between 1997 and 2003. CSF flow was classified as "abnormal" if biphasic flow was either absent or decreased through the aqueduct, fourth ventricle and its outlets, the foramen magnum, or ventral or dorsal to the cervical spinal cord. If no evidence of decreased flow was noted, CSF flow was classified as "normal." The association between preoperative CSF flow dynamics, all recorded variables, and long-term outcome was assessed using multivariate proportional hazards regression analysis. All patients had tonsil herniation more than 5 mm below the foramen magnum (average, 11 +/- 5 mm). Abnormal hindbrain CSF flow was observed in 81% of patients (43% complete obstruction, 38% reduced flow). Normal CSF flow was observed in 19% of patients. In multivariate analysis, patients with normal preoperative hindbrain CSF flow were 4.8-fold more likely to experience symptom recurrence after surgery (relative risk, 4.85; 95% confidence interval, 1.88-12.5; P < 0.001) regardless of degree of tonsillar ectopia or presence of syringomyelia. Isolated frontal headache (relative risk, 4.16; 95% confidence interval, 1.7-9.8; P < 0.05) and scoliosis (relative risk, 9.2; 95% confidence interval, 1.7-10.5; P < 0.001) also were independent risk factors for symptom recurrence. Normal preoperative hindbrain CSF flow was an independent risk factor for treatment failure after decompression for Chiari I malformation regardless of the degree of tonsillar ectopia. Cine phase-contrast magnetic resonance imaging may be a valuable tool in identifying patients who are less likely to respond to surgical decompression for Chiari I malformation.

Relationship of Cine Phase-Contrast MRI to Outcome after Decompression for Chiari I Malformation.

BACKGROUND Many patients with symptomatic Chiari I malformation experience symptom recurrence after surgical decompression. Identification of predictors of outcome is needed to better select patients most likely to benefit from surgical intervention. We examined whether CSF flow dynamics assessed by cine phase-contrast MRI could independently predict response to posterior fossa decompression for Chiari I malformation. METHODS Pre and postoperative CSF flow dynamics were assessed by cine phase contrast magnetic resonance imaging in 130 consecutive patients receiving posterior fossa decompression for Chiari I malformation between 1997 and 2003. CSF flow was classified as “abnormal CSF flow” if biphasic flow was either absent or decreased through the aqueduct, fourth ventricle and its outlets, the foramen magnum, or ventral or dorsal to the cervical spinal cord. If no evidence of decreased flow was noted CSF flow was classified as “normal.” The association between pre-operative CSF flow dynamics, all recorded variables, and long-term outcome was assessed utilizing multivariate proportional hazards regression analysis. RESULTS All patients had tonsil herniation > 5mm below the foramen magnum (average 11 ± 5mm). Abnormal hindbrain CSF flow was observed in 81% of patients (43% complete obstruction, 38% reduced flow). Normal CSF flow was observed in 19% of patients. In multivariate analysis, patients with normal preoperative hindbrain CSF flow were 4.8-fold more likely to experience symptom recurrence following surgery (RR, 4.85; 95%CI, 1.88–12.5, P < 0.001) regardless of degree of tonsillar ectopia or presence of syringomyelia. Isolated frontal headache (RR, 4.16; 95%CI, 1.7–9.8, P < 0.05) and scoliosis (RR, 9.2; 95% CI, 1.7–10.5, P < 0.001) were also independent risk factors for symptom recurrence. CONCLUSIONS Normal preoperative hindbrain CSF flow was an independent risk factor for treatment failure after decompression for Chiari I malformation regardless of the degree of tonsilar ectopia. Cine phase-contrast MRI may be a valuable tool in identifying patients less likely to respond to surgical decompression for Chiari I malformation.

Unilateral occipital hyperhidrosis following Chiari I decompression: case report and a review of the literature

Paroxysmal unilateral cephalic hyperhidrosis is a rare disorder of the autonomic nervous system. We report an adult male who developed this disorder almost 20 years after posterior fossa decompression for Chiari I malformation with syringomyelia as a child. Further, the patient presented with spastic diplegia. To date, this patient has refused further operative intervention. The medical literature is reviewed regarding this unusual phenomenon. To our knowledge, hyperhidrosis of the occiput has not been previously reported in a patient with Chiari I malformation with an associated syringomyelia.

Surgical experience in 130 pediatric patients with Chiari I malformations.

The aim of this study was to present the long-term findings of a surgical series of pediatric patients with Chiari I malformations. One hundred thirty symptomatic pediatric patients with Chiari I malformations underwent posterior fossa decompression. The age in this group of patients ranged from 2 months to 20 years (mean 11 years). The length of the hospital stay extended from 2 to 7 days (mean 2.7 days), and follow up was from 3 months to 15 years (mean 4.2 years). Patients most often presented with headache/neck pain (38%) and scoliosis (18%). Examples of associated diagnoses included neurofibromatosis Type 1 (5.5%), hydrocephalus (11%), idiopathic growth hormone deficiency (5.5%), and Klippel-Feil anomaly (5%). Syringes were present in 58% of patients. Seventeen percent of patients had caudal displacement of the brainstem and fourth ventricle. Postoperative relief of preoperative pathologies was experienced in 83% of patients. Of the most common presenting symptoms--headache/neck pain and scoliosis--12 and 17%, respectively, were not alleviated postoperatively. Complications occurred in 2.3% of this group and included the development of acute hydrocephalus postoperatively and severe life-threatening signs of brainstem compression that necessitated a transoral odontoidectomy. Nine patients have had to undergo repeated operations for continued symptoms or persistent large syringes. During surgery 10 patients (7.7%) were found to have arachnoid veils occluding the fourth ventricular outlet, and nine of these had syringomyelia. In our experience almost all syringes will stabilize or improve with posterior fossa decompression and duraplasty. The authors believe this to be the largest reported series of pediatric patients who have undergone posterior fossa decompression for Chiari I malformations.

Posterior fossa decompression for Chiari I deformity, including resection of the cerebellar tonsils.

This is an analysis of 19 consecutive cases of symptomatic patients with Chiari I deformities, undertaken to evaluate the long-term effect of posterior fossa decompression and duraplasty, assessed by postoperative imaging. Sixteen of the patients had syringomyelia and three had foramen magnum syndromes without a syrinx. Eighteen patients underwent posterior fossa craniectomy, subpial resection of the cerebellar tonsils, and duraplasty. Four patients were 16 years of age or younger. One of the children with syringomyelia had a posterior fossa decompression without resection of the tonsils. In the 15 patients with syringomyelia whose surgery included resection of the tonsils, the syrinx was reduced or resolved in 14. The patient whose syrinx did not change was a child with a lumbosacral lipoma. Three patients had syndromes of the foramen magnum without a syrinx, and of these only a patient with prior chemical and bacterial meningitis caused by a lumboureteral shunt failed to improve dramatically. When our patients are combined with 40 in the literature treated by decompression and duraplasty, 51 of 55 patients had reduction or resolution of the syrinx. Although it does not clearly affect the result, resection of the tonsils can be done safely.