Chicago Chiari Outcome Scale Research Articles

Analysis of Clinical and Radiographic Outcomes of the Angle between Clivus and Supraocciput in Patients with Chiari's Malformation Type I Following Surgical Decompression

Background The objective of this study was to investigate whether different angles between the clivus and supraocciput (C-SO angle) in patients with Chiari's malformation type I (CMI) after posterior fossa decompression lead to different clinical and radiographic outcomes. Methods A total of 73 patients who underwent surgical decompression at our institution between 2010 and 2016 were retrospectively divided into two groups: group A, with an angle less than 96 degrees, and group B, with an angle ≥ 96 degrees. Patient clinical outcomes were determined using the Chicago Chiari Outcome Scale (CCOS), and radiographic outcomes were determined by changes in the syrinx size before and after surgery. Direct comparisons were made between the two groups. Results There were no statistically significant differences between the two groups regarding demographics, preoperative symptoms or radiographic characteristics ( p > 0.05), except for the cerebellar tonsillar descent ( p ≤ 0.001). The mean overall CCOS score was 13.11 ± 1.99. The total CCOS score was significantly different between the two patient groups ( p < 0.05). Moreover, group A demonstrated significantly better postoperative improvements than group B in clinical outcome measures based on the CCOS system ( p = 0.035). For radiographic outcomes, the change in the syrinx between the two groups was also significantly different, with a value p = 0.024. Conclusions A direct comparison between the two groups revealed that a smaller C-OS angle (< 96 degrees) was related to unsatisfactory clinical and radiographic outcomes. Thus, the C-OS angle may emerge as a predictor of clinical or radiographic outcomes following surgical decompression in patients with CMI.

Sequential Enlargement of Posterior Fossa After Duraplasty for Chiari Malformation Type 1

ObjectiveThere are several material options for duraplasty in surgery for foramen magnum decompression (FMD). We retrospectively analyzed surgical results and the impact of sequential alteration of posterior fossa (PF) size in patients with Chiari malformation type 1 after duraplasty using local fascia.MethodsThe patients with Chiari malformation type 1 who underwent FMD with duraplasty using local fascia at our institution between 2004 and 2015 were included in the study. Some pediatric patients who underwent FMD without duraplasty and patients with insufficient follow-up data were excluded. Improvement of clinical signs, regression of syrinx, and temporal alteration of PF size were analyzed with perioperative magnetic resonance imaging. Postoperative clinical outcomes were evaluated at the final follow-up using the Chicago Chiari Outcome Scale. Correlations between the PF size alteration and size of dural patch or Chicago Chiari Outcome Scale were statistically analyzed.ResultsTwelve patients were included in this study. The mean age of the patients was 31.9 (range, 18–48) years. Syrinx was incorporated in 11 patients and regressed postoperatively in all patients. The PF was significantly enlarged sequentially over time (P < 0.05). The degree of enlargement was positively correlated with size of the fascial patch (r = 0.540). Postoperative clinical outcomes at final follow-up were positively correlated with the degree of PF enlargement (r = 0.678).ConclusionsThe PF was enlarged sequentially over time after duraplasty using local fascia. The degree of enlargement was positively correlated with the size of the fascial patch and the likelihood of a favorable postoperative outcome.

Prognostic Value of Craniovertebral Junction Diffusion Tensor Imaging in Patients with Chiari Type 1 Malformation.

To examine the spinal cord status by using diffusion tensor imagıng (DTI) and tractography preoperatively and postoperatively in patients with Chiari malformation type 1 (CM1) and compare the results with the data obtained from healthy people. Overall, 48 patients (33 patients with CM1, and 15 in the control group for DTI and tractography measurements) were included in the study. Mean age was 37.7 ± 11.8 years (minimum and maximum: 12 and 57 years). The DTI and tractography data were obtained from the craniocervical region in patients with CM1 and control group. Patients with CM1 were operated using the suboccipital decompression technique without opening the dura. Surgical results were evaluated using Chicago Chiari Outcome Scale (CCOS) and Asgari scale. Based on the CCOS and Asgari scale results, the surgical technique was determined to be clinically beneficial. The DTI and tractography values from the pontobulbar, cervicomedullary, and spinal cord C3â€"4 levels in patients with CM1 were compared to those of the control group. These values were observed to be near normal after surgery in patients with CM1. Based on the improvement in DTI-tractography data observed in our study, DTI and tractography can serve as a guiding measurement method for assessing the prognosis of patients with CM1.

Bony Decompression for Chiari Malformation Type I: Long-Term Follow-Up.

Several surgical techniques are used for the management of Chiari malformation typeI (CM-I). Bony posterior fossa decompression is considered a good option in children, though with a higher risk of requiring reoperation. However, there is not enough evidence from the series in the literature, which are often limited by inadequate follow-up. The goal of this study was to assess the effectiveness of suboccipital craniectomy alone in children after long-term follow-up. Forty-two children (25 female and 17 male; mean age 6.7years), operated on with bony decompression alone, were retrospectively reviewed. All patients underwent suboccipital craniectomy. Thirty-eight children required C1 laminectomy, and 21 also underwent dural delamination on the basis of intraoperative ultrasound investigations. The outcome was assessed using the traditional measurement and the Chicago Chiari Outcome Scale (CCOS). The mean follow-up period was 11.3years (range 5-15years). Headache was the most frequent preoperative symptom (81%), followed by neck pain (40%), vertigo (40%), ataxia (26%), and upper and lower extremity paraesthesia (26%). Syringomyelia was present in 19 patients (45%). Resolution and significant improvement of preoperative clinical symptoms were observed in 36.5% and 21.5% of cases, respectively. Three children required adjunctive surgery for symptom recurrence (7%). The tonsil position and syringomyelia were normalized or improved in 50% and 79% of cases, respectively. No complications occurred. According to the CCOS scores, 69.5% of children had an excellent outcome, 28.5% had a functional outcome and 2% had an impaired outcome. Bony decompression alone is an effective, safe and long-lasting treatment for children with CM-I. A certain risk of symptom recurrence requiring new surgery exists, but it is widely counterbalanced by the low risk of complications. Careful patient selection is crucial for a good outcome. Prospective and randomized studies are needed for further validation.

Clinical Significance of Variable Clivus Gradients in Patients with Chiari Malformation Type I After Surgical Decompression: A Retrospective Analysis

Previous studies have shown that the clivus angle gradient is significantly decreased in patients with Chiari malformation type I (CMI) with an associated syrinx compared with patients with CMI only and a healthy population. To date, the relationship between the clivus gradient and clinical outcomes has remained unclear. The objective of the present study was to investigate whether different clivus gradients (∠α) in CMI after posterior fossa decompression will lead to different clinical outcomes. A total of 86 patients who had undergone surgical decompression at our institution from 2010 to 2016 were retrospectively divided into 2 groups: group A, with a gradient angle >44°, and group B, with an angle ≤44°. The patients' outcomes were determined using the Chicago Chiari Outcome Scale (CCOS). Direct comparisons were made between the 2 groups. No statistically significant differences were found between the 2 groups in demographic data, preoperative symptoms, postoperative complications, or radiographic characteristics (P > 0.05), except for the length of the postoperative hospital stay (P= 0.006). The mean overall CCOS score was 12.80 ± 2.08. The total CCOS score was significantly different statistically between the 2 groups (P< 0.05). Moreover, group A demonstrated significantly better postoperative improvements compared with groupBin the clinical outcome measures using the CCOS (P= 0.021). A direct comparison between the 2 groups revealed that a decreased clivus gradient was related to unsatisfactory clinical outcomes. Thus, clivus gradients might emerge as a predictor of clinical outcomes after surgical decompression in patients with CMI.

Functional Outcome for Chiari Malformation Using a Novel Scoring System

Abstract Background The authors report functional outcomes comparing various surgical techniques, using a Chiari-specific assessment tool. They also intend to externally validate the performance of the CCOS by comparing with gestalt outcome. Methods Total cohort comprised 73 surgically treated patients, and patients were divided into two groups: patients who were operated upon at the authors’ institute and those who were evaluated at their institute but underwent surgery elsewhere due to various reasons. Functional outcome was evaluated on the basis of the Chicago Chiari outcome scale (CCOS) and gestalt outcome scale. Mean duration of follow-up was 10.23 ± 5.8 months. Results In the authors’ cohort of 73 patients, 76.70% (n = 56) were improved, 23.30% (n = 17) were unchanged, and none of them deteriorated. The median CCOS was 14 ± 1.34 (range: 11–16). There was no statistical difference in outcome between the different operative groups (foramen magnum decompression, duraplasty, tonsillar resection “other”). The CCOS value of 14 has excellent sensitivity (0.95) and good specificity (0.746) for identifying patients with good gestalt outcome. Conclusion The authors found a clear correlation between higher CCOS score and gestalt outcome. There was no statistical difference in outcome between the different operative groups.

Clinical Characteristics, Imaging Findings and Surgical Outcomes of Chiari Malformation Type I in Pediatric and Adult Patients.

A growing number of children and adolescents are being diagnosed as Chiari malformation type I (CM-I) for behavioral disorders, developmental delay, seizures, or abnormal orpharyngeal function. The aim of this study was to compare the clinical characteristics, imaging findings and surgical outcomes of CM-I in pediatric and adult patients. Between January 2014 and June 2017, 84 patients with CM-I underwent surgical treatment in our department. We divided the patients into two groups: pediatric group (n=11, age <18 years) and adult group (n=73, age ≥18 years). Data on clinical characteristics, imaging findings, surgical outcomes, and prognosis were retrospectively reviewed and compared between these two groups. For clinical presentation, scoliosis (36.4%) and developmental delay (36.4%) were more common in pediatric patients, whereas, sensory disturbance (58.9%) and motor weakness (41.1%) were more common in adult patients. Imaging findings showed that the incidence of hydrocephalus and craniovertebral junctional abnormalities was significantly higher in pediatric group than in adult group (P<0.05). Compared to adult group, pediatric group showed a better improvement or resolution of syrinx and tonsillar herniation after surgical treatments (P<0.05). The total Chicago Chiari Outcome Scale (CCOS) score in pediatric patients at the last followup was significantly higher than that in adult patients (P=0.002). In conclusion, the clinical characteristics and imaging findings appeared to be different in pediatric and adult patients with CM-I. The surgical outcomes of pediatric patients were shown to be significantly better than those of adult patients.

A points-based algorithm for prognosticating clinical outcome of Chiari malformation Type I with syringomyelia: results from a predictive model analysis of 82 surgically managed adult patients.

OBJECTIVE Although various predictors of postoperative outcome have been previously identified in patients with Chiari malformation Type I (CMI) with syringomyelia, there is no known algorithm for predicting a multifactorial outcome measure in this widely studied disorder. Using one of the largest preoperative variable arrays used so far in CMI research, the authors attempted to generate a formula for predicting postoperative outcome. METHODS Data from the clinical records of 82 symptomatic adult patients with CMI and altered hindbrain CSF flow who were managed with foramen magnum decompression, C-1 laminectomy, and duraplasty over an 8-year period were collected and analyzed. Various preoperative clinical and radiological variables in the 57 patients who formed the study cohort were assessed in a bivariate analysis to determine their ability to predict clinical outcome (as measured on the Chicago Chiari Outcome Scale [CCOS]) and the resolution of syrinx at the last follow-up. The variables that were significant in the bivariate analysis were further analyzed in a multiple linear regression analysis. Different regression models were tested, and the model with the best prediction of CCOS was identified and internally validated in a subcohort of 25 patients. RESULTS There was no correlation between CCOS score and syrinx resolution (p = 0.24) at a mean ± SD follow-up of 40.29 ± 10.36 months. Multiple linear regression analysis revealed that the presence of gait instability, obex position, and the M-line-fourth ventricle vertex (FVV) distance correlated with CCOS score, while the presence of motor deficits was associated with poor syrinx resolution (p ≤ 0.05). The algorithm generated from the regression model demonstrated good diagnostic accuracy (area under curve 0.81), with a score of more than 128 points demonstrating 100% specificity for clinical improvement (CCOS score of 11 or greater). The model had excellent reliability (κ = 0.85) and was validated with fair accuracy in the validation cohort (area under the curve 0.75). CONCLUSIONS The presence of gait imbalance and motor deficits independently predict worse clinical and radiological outcomes, respectively, after decompressive surgery for CMI with altered hindbrain CSF flow. Caudal displacement of the obex and a shorter M-line-FVV distance correlated with good CCOS scores, indicating that patients with a greater degree of hindbrain pathology respond better to surgery. The proposed points-based algorithm has good predictive value for postoperative multifactorial outcome in these patients.

Comparison of Three Different Cranio-Cervical Decompression Procedures in Children with Chiari Malformation Type I: Does the Surgical Technique Matter?

Background/Aims: A broad spectrum of cranio-cervical decompression techniques (CCD) is employed for the treatment of Chiari malformation type I (CM1). The aim of this study was to compare the clinical and radiological outcome of 3 different CCD performed in a single paediatric centre. Methods: A retrospective analysis of children treated between 2008 and 2014 was performed. Three different surgical techniques were offered to the patients: an extradural osseo-ligamentous bony decompression (BD), or a BD plus opening of the dura either without duroplasty (DOWD) or with watertight expansile duroplasty (DOPD). The primary clinical outcome was measured by utilizing the Chicago Chiari Outcome Scale (CCOS). Results: Forty-six children underwent 51 CCD: 17 BD, 17 DOWD, and 17 DOPD. The median follow-up period was 46 months (16-98 months). Patients who underwent BD had a shorter length of hospital stay than those who underwent DPTC and DOWD. Clinical improvement, defined by the mean CCOS score, was comparable in patients receiving BD (n = 14.6) and DOPD (n = 14.5), but lower in patients with DOWD (n = 12). Post-operative complications were noted in 7 DOWD patients (41%) and 3 DOPD patients (17.6%). Conclusions: BD is a safe and effective procedure with comparable clinical and radiological outcomes to DOPD in children with CM1. The risk of post-operative complications and worse clinical outcome was noted to be higher when performing a DOWD.

Surgical Decompression for Chiari Malformation Type I: An Age-Based Outcomes Study Based on the Chicago Chiari Outcome Scale

There is currently inadequate evidence on the efficacy of surgical decompression for Chiari malformation type I (CM1) in different age groups of patients. In this study, we compared postoperative outcomes across 3 different age groups using the Chicago Chiari Outcome Scale (CCOS). A total of 144 patients who underwent Chiari decompression at our institution between 2008 and 2014 were divided into 3 groups: group A, children age 0-18 years; group B, younger adults age 19-40 years; and group C, older adults, age 41+ years. Patient outcomes were assigned a numerical value based on the CCOS and subjected to statistical analysis. Direct comparisons were made across the 3 age groups. The mean overall score was 14.0 over a meanfollow-up of 27.2 months. All 3 groups demonstrated clinical improvement following Chiari decompression; however, group A demonstrated significantly better postoperative improvements than groups B and C in total CCOS scores (7.8% and 12.2%, respectively; P < 0.001) and all the component scores except complications. Group B was not significantly different from group C in total score or any of the component scores. There was a logarithmic relationship between age and outcome (R2= 0.64), in which the outcome scores experienced an initial decline with increasing age but leveled off by early adulthood. A direct comparison among the age groups revealed a negative age effect on surgical decompression outcomes in CM1 patients. Children performed significantly better than younger and older adults. This finding supports early surgical intervention for symptomatic pediatric patients to achieve long-term surgical benefit.

Technique for Mini-open Decompression of Chiari Type I Malformation in Adults.

The technique for decompression of Chiari type I malformation relies on open exposure of craniocervical junction for suboccipital craniectomy and upper cervical laminectomy with or without duraplasty. There is no detailed technical report of a minimally invasive approach for Chiari decompression in adults. To describe a mini-open technique for decompression of Chiari type I malformation (including duraplasty) in adults. Six consecutive adult patients with symptomatic Chiari type I malformation underwent decompression through a 3 to 4 cm midline incision via a speculum retractor. All patients underwent a limited suboccipital craniectomy and C1 laminectomy with an ultrasonic bone scalpel. All patients underwent duraplasty with a synthetic dural substitute. In the 2 patients with syringomyelia, the arachnoid was opened and intradural dissection was carried out. In the remaining 4 patients, the arachnoid was left intact. All operations were completed successfully through the mini-open exposure. Mean surgery time, blood loss, and length of stay were 114 min, 55 mL, and 1.3 days, respectively. Mean follow-up was 13.2 months (range 9-18). All patients had excellent clinical outcomes as defined by scores of 15 (3 patients) or 16 (3 patients) on Chicago Chiari Outcome Scale. There were no neurological complications or cerebrospinal fluid leaks. Postop computed tomography revealed good boney decompression. In the 2 patients with syringomyelia, MRI at 6 months revealed resolution of the syrinx. Decompression of Chiari type I malformation in adults can be performed safely and effectively through the mini-open exposure described in this report.

Long-term outcome of surgical treatment of Chiari malformation without syringomyelia.

Surgical treatment for CM without syringomyelia is still under debate. The aim of this study was to evaluate the long-term outcome of surgically treated patients for CM-I without syringomyelia. We selected all adult patients who underwent surgery for CM-I without syringomyelia between 1993 and 2010. Only patients with long term follow-up (>5 years) were included. Clinical manifestations, radiologic features, and follow-up data were analyzed. Patient's outcome was assessed using the Chicago Chiari Outcome Scale (CCOS). Patient's outcome was classified also as: "improved," "unchanged," or "worse." Among 38 patients, 27 were females and 11 were males. Age ranged from 18 to 65 years (mean age 41 years). The average follow-up duration was 75 months (range 60-168 months). The most frequent symptoms of presentation were: headache (60%), neck pain (52.6%), postural or gait instability (47.3%), upper limb paresthesias (44.7%). The most frequent signs of presentation were: nystagmus (44.7%), pyramidal signs (31.5%), gait/balance impairment (23.6%). Surgical treatment resulted in a long-term success rate of 84.2% (32 patients improved at last follow-up). Thirty-one patients (81.5%) achieved a CCOS score between 13 and 16. Headache improved in 86.9% of patients, gait impairment in 83.3%, paresthesias in 70% and neck pain in 65.2%. Two patients (5.2%) were unchanged after surgery, four patients (10.5%) showed recurrence of their symptoms. There was no mortality. Surgery is a safe and long-term effective treatment for patients with CM-I without syringomyelia in the majority of patients.

Symptomatic Outcome after Bone-only Suboccipital Decompression in Adult Patients with Chiari Type I Malformations in the Absence of Hydromyelia or Hydrocephalus.

Background Type I Chiari malformation presents without an associated hydromyelia in 30 to 70% of cases, yet there is no agreement regarding the optimal surgical treatment for these patients. We review our experience for treating symptomatic adult type I Chiari malformation without hydromyelia using a suboccipital bone decompression of the hindbrain and no duraplasty in 12 adult patients. Outcome was measured according to the Chicago Chiari Outcome Scale (CCOS). Results Nine of 12 patients were female; average age at surgery was 34.4 years (range: 17-67 years). Average duration of symptoms prior to surgery was 9.6 years (2 months-29 years). The most common symptom was head and/or neck pain (11/12 patients). All patients additionally presented with at least one non-pain symptom. Mean degree of tonsillar herniation on magnetic resonance imaging was 6.8 mm (range: 5-12 mm) below McRae's line. Operative time was on average 68 minutes (range: 47-120 minutes). No surgical complications were noted in any patient. Length of hospital stay was 2 days (1 overnight) for all patients. Mean follow-up was 167 weeks (range: 13-378 weeks). CCOS for all patients on average was 14.50 (range: 12-16). Pain symptoms underwent improvement (7/11 [63.6%]) or complete resolution (4/11 [36.4%]) in all affected patients. A shorter duration of preoperative symptoms significantly correlated with a better CCOS (p = 0.03). Degree of tonsillar herniation had no significant effect on CCOS (p = 0.67). Of non-pain symptoms, paresthesias/dysesthesias and visual symptoms improved or resolved completely in all affected patients. No patient experienced a worsening of either pain or non-pain symptoms. Conclusion In the subset of adult patients with a type I Chiari malformation and no associated hydromyelia, a craniectomy without an additional opening of the dura may achieve good overall results according to the CCOS.

"Stealth cranioplasty:" A novel endeavor for symptomatic adult Chiari I patients with syringomyelia: Technical note, appraisal, and philosophical considerations.

Aim and Objective:In this article, we describe a novel technique of reconstruction of posterior fossa by cranioplasty with use of preshaped titanium mesh following posterior fossa decompression (PFD) for Chiari malformation type I (CMI) with syringomyelia (SM) in symptomatic adults.Materials and Methods:Eleven patients underwent limited PFD and expansive cranioplasty with preshaped titanium mesh, what we term as “Stealth Cranioplasty” (SCP), following arachnoid preserving duraplasty (APD) and hexagonal tenting of the duraplasty with the cranioplasty (HTDC) for the management of symptomatic adult CMI with SM. All these patients had syringes extending from 3 to >10 vertebral levels.Results:Seven male and four female symptomatic CMI adult patients, between age ranges of 22 and 44 years (mean 29.45 years), presented with different neurological symptoms related to CMI and SM for 6–84 months (mean 37.09 months). All the patients underwent PFD, APD followed by SCP and HTDC and were followed up for 7–54 months (mean 35.90 months). Of 11 patients, 8 patients improved according to the Chicago Chiari Outcome Scale (CCOS) with score of 13–15 while 3 patients remained unchanged with CCOS of 12, and there was no worsening. There was no complication related to Chiari surgery in any of the patients. All the patients had good reestablishment of cisterna magna. Two patients had marked reduction of syrinx while eight patients had moderate-to-mild reduction and one patient had no change of syrinx. None of the patients needed redo surgery.Conclusion:SCP is an effective, fruitful, and cost-effective technique for the management of symptomatic adult CMI with SM. This technique has the advantages of preventing complications and recurrences in addition to the improvement of symptoms by addressing the basic pathology.

Surgical Outcome after Posterior Fossa Decompression with and without Duraplasty in Adult Chiari Malformation Type-I

Background Data: Adult Chiari malformation is a heterogeneous group of conditions, with the underlying commonality of disruption of normal CSF flow through the foramen magnum. Some cases are congenital, but others are acquired. The optimal surgical treatment of adult Chiari malformation type-I is unclear. Purpose: To evaluate the operative and postoperative results of extradural and intradural approaches in the treatment of Chiari malformation type-I.Study Design: A descriptive retrospective clinical case study. Patients and Methods: Twenty patients underwent surgery for adult Chiari malformation type-I. They were divided into two groups; posterior fossa decompression group and posterior fossa decompression with duroplasty group. Each group included 10 patients. They were operated between 2008and 2015. Participants were evaluated pre-operatively and post-operatively every three months. Operative time, hospital stay and complications were assessed. The clinical outcomes were compared between the two groups using The Chicago Chiari Outcome Scale. Results: No statistically significant differences were found between the decompression and duroplasty groups with regard to demographics, preoperative symptoms, radiographic characteristics, and clinical outcomes. However, the operative time, hospital stay and aseptic meningitis were higher in the duroplasty group.Conclusion: The clinical outcome of posterior fossa decompression is nearly identical to that of posterior fossa decompression with duroplasty in adult patients with Chiari type-I; however, the operative time, hospital stay and complication rate is higher in duroplasty group. (2016ESJ113)

Magnetic resonance imaging-based measures predictive of short-term surgical outcome in patients with Chiari malformation Type I: a pilot study.

OBJECTIVE This study identifies quantitative imaging-based measures in patients with Chiari malformation Type I (CM-I) that are associated with positive outcomes after suboccipital decompression with duraplasty. METHODS Fifteen patients in whom CM-I was newly diagnosed underwent MRI preoperatively and 3 months postoperatively. More than 20 previously described morphological and physiological parameters were derived to assess quantitatively the impact of surgery. Postsurgical clinical outcomes were assessed in 2 ways, based on resolution of the patient's chief complaint and using a modified Chicago Chiari Outcome Scale (CCOS). Statistical analyses were performed to identify measures that were different between the unfavorable- and favorable-outcome cohorts. Multivariate analysis was used to identify the strongest predictors of outcome. RESULTS The strongest physiological parameter predictive of outcome was the preoperative maximal cord displacement in the upper cervical region during the cardiac cycle, which was significantly larger in the favorable-outcome subcohorts for both outcome types (p < 0.05). Several hydrodynamic measures revealed significantly larger preoperative-to-postoperative changes in the favorable-outcome subcohort. Predictor sets for the chief-complaint classification included the cord displacement, percent venous drainage through the jugular veins, and normalized cerebral blood flow with 93.3% accuracy. Maximal cord displacement combined with intracranial volume change predicted outcome based on the modified CCOS classification with similar accuracy. CONCLUSIONS Tested physiological measures were stronger predictors of outcome than the morphological measures in patients with CM-I. Maximal cord displacement and intracranial volume change during the cardiac cycle together with a measure that reflects the cerebral venous drainage pathway emerged as likely predictors of decompression outcome in patients with CM-I.

Comparison of posterior fossa decompression with or without duraplasty in children with Type I Chiari malformation

Chiari malformation type I (CM1) is a common and often debilitating neurosurgical disease. Whether to treat CM1 patients with a traditional posterior fossa decompression with duraplasty (PFDD) or a less invasive extradural decompression (PFDO) is controversial. The purpose of this study was to compare clinical outcome and syrinx resolution between the two procedures. We retrospectively reviewed the records of 36 patients treated with PFDD and 29 patients with PFDO between 2003 and 2011. We compared baseline demographic, clinical, and radiographic characteristics. The primary clinical outcome was the Chicago Chiari Outcome Scale (CCOS). The primary radiographic outcome was qualitative syrinx improvement or resolution. At baseline, age and sex distributions, radiographic characteristics, and presenting symptoms were similar in patients undergoing PFDD and PFDO. Patients undergoing PFDO had shorter surgical time (1.5 vs. 2.8 h; p < 0.001) and length of hospital stay (2.1 days compared to 3.3 days; p < 0.001). Cerebrospinal fluid-related complications were more common in patients receiving PFDD (7/36) than PFDO (0/29) (p = 0.014). Clinical improvement, defined by the mean CCOS score, was comparable in patients receiving PFDO (14.7) and PFDD (14.6) (p = 0.70). Among patients with postoperative syrinx imaging, 10/13 in the PFDD group improved or resolved, compared to 8/8 in the PFDO group (p = 0.26). Extradural decompression for CM1 produces comparable rates of clinical and radiographic improvement as the more invasive decompression with duraplasty. Given the increased morbidity and resource utilization associated with PFDD, PFDO should be considered an attractive first-line option for most CM1 patients.

External validation of the Chicago Chiari Outcome Scale.

Historically, assessment of clinical outcomes following surgical management of Chiari malformation Type I (CM-I) has been challenging due to the lack of a validated instrument for widespread use. The Chicago Chiari Outcome Scale (CCOS) is a novel system intended to provide a less subjective evaluation of outcomes for patients with CM-I. The goal of this study was to externally validate the performance of the CCOS. Patients undergoing surgery for CM-I between 2001 and 2012 were reviewed (n = 292). Inclusion criteria for this study were as follows: 1) patients receiving primary posterior fossa decompression; 2) at least 5.5 months of postoperative clinical follow-up; and 3) patients ≤ 18 years of age at the time of surgery. Outcomes were evaluated using the CCOS, along with a "gestalt" impression of whether patients experienced significant improvement after surgery. A subgroup of 118 consecutive patients undergoing operations between 2008 and 2010 was selected for analysis of interrater reliability (n = 73 meeting inclusion/exclusion criteria). In this subgroup, gestalt and CCOS scores were independently determined by 2 reviewers, and interrater reliability was assessed using the intraclass correlation coefficient (ICC) and kappa (κ) statistic. The median CCOS score was 14, and 67% of patients had improved gestalt scores after surgery. Overall, the CCOS was effective at identifying patients with improved outcome after surgery (area under curve = 0.951). The interrater reliability of the CCOS (ICC = 0.71) was high, although the reliability of the component scores ranged from poor to good (ICC 0.23-0.89). The functionality subscore demonstrated a low ICC and did not add to the predictive ability of the logistic regression model (likelihood ratio = 1.8, p = 0.18). When analyzing gestalt outcome, there was moderate agreement between raters (κ = 0.56). In this external validation study, the CCOS was effective at identifying patients with improved outcomes and proved more reliable than the authors' gestalt impression of outcome. However, certain component subscores (functionality and nonpain symptoms) were found to be less reliable, and may benefit from further definition in score assignment. In particular, the functionality subscore does not add to the predictive ability of the CCOS, and may be unnecessary. Overall, the authors found the CCOS to be an improvement over the previously used assessment of outcome at their institution.

Positive and negative predictors for good outcome after decompressive surgery for Chiari malformation type 1 as scored on the Chicago Chiari Outcome Scale

Objective: Posterior fossa decompression (PFD) is commonly applied as treatment for Chiari malformation type 1 (CM1), an entity which is associated with a variety of presenting symptoms but little data correlating symptoms to surgical outcome. We applied the Chicago Chiari Outcome Scale (CCOS), a novel 16-point tool for evaluating outcome, to a consecutive series of CM1 patients to identify specific factors or symptoms that predispose to a better or worse surgical outcome.Methods: A series of 167 CM1 patients who underwent initial PFD at our institution (consisting of suboccipital craniectomy, C1 laminectomy, subarachnoid exploration, and expansile autologous pericranial duraplasty) were reviewed. Pre-operative signs, symptoms, and characteristics were recorded, and odds ratios were calculated to identify significant pre-operative factors corresponding to a better or worse outcome on the CCOS.Results: Sensory deficits and peripheral neuropathy correlated with a lower score on the CCOS. Younger age at the time of surgery and, strikingly, presence of syringomyelia both correlated with a higher CCOS score.Discussion: Our results identify specific presenting factors that correlated with a better or worse outcome after CM1 decompression. These data also demonstrate that CCOS scoring allows for a rigorous comparison of outcome in different patient populations and between variable operative techniques. Application of CCOS scoring to a larger patient population undergoing a variety of operative CM1 treatments should allow for better-informed decisions regarding patient selection and treatment options for CM1.

A Novel Scoring System for Assessing Chiari Malformation Type I Treatment Outcomes

Outcome assessment for the management of Chiari malformation type 1 is difficult because of the lack of a reliable and specific surgical outcome assessment scale. Such a scale could reliably correlate postoperative outcomes with preoperative symptoms. We developed a novel scoring system and applied it retrospectively to 146 patients treated at our institution in order to create and verify a simple and quantifiable assessment of Chiari outcomes. The Chicago Chiari Outcome Scale (CCOS) uses 4 postoperative outcome categories (pain, nonpain symptoms, functionality, and complications) graded 1 to 4 for a total possible score of 16. As a comparison with current Chiari outcome methodology, each patient was also placed into a gestalt outcome group of "improved," "unchanged," or "worse" (I/U/W). Patients were stratified by CCOS scores and by I/U/W group. Stratifying patients by total CCOS scores showed that patients who achieved CCOS scores between 13 and 16 were predominantly in the I/U/W improved group (n = 101, 69%); scores between 9 and 12 were predominantly I/U/W unchanged (n = 39, 27%), and scores between 4 and 8 were I/U/W worse (n = 6, 4%). Symptom subscore results provided insight into the specifics of the overall outcome in addition to the more quantitative nature of the 16-point scale. We describe a CCOS that assigns higher scores to patients judged improved by gestalt I/U/W ratings and lower scores to those who were unchanged or worse while defining outcome in 4 specific subcategories. As such, this CCOS should allow for a more unified and quantifiable outcome assessment after Chiari surgery.