Predicting the presence of 4th ventricular outlet obstruction in Chiari I Malformation.

INTRODUCTION: A subset of children with Chiari 1 malformation (CM-1) have a 4th ventricle arachnoid veil-a thin membrane covering the outlet of the 4th ventricle. Studies suggest that failure to disrupt this veil during posterior fossa decompression can reduce the likelihood of syringomyelia resolution. However, there is no reliable method for predicting the presence of the veil without direct surgical exploration. This study aims to evaluate the association between pre-operative symptoms, radiographic measurements, and the arachnoid veil. METHODS: A retrospective review of an institutional database of children evaluated for CM-I was conducted. For patients treated with surgery, operative notes were reviewed to determine if an arachnoid veil was present. Logistic regression was used to test for relationship of clinical variables and radiographic measurements with the presence of an arachnoid veil. RESULTS: Out of 997 children with CM-1, 226 surgical patients were included in the analysis after excluding those with inadequate documentation. An arachnoid veil was found in 23 patients (10.2%). Larger syrinx, spinal canal, and thecal sac diameters were significantly associated with the presence of a veil, with odds ratios of 1.23 (95% CI 1.2-1.48; p = 0.03), 1.27 (95% CI 1.02-1.59; p = 0.03), and 1.35 (95% CI 1.03-1.77; p = 0.03), respectively. No significant associations were found with any signs or symptoms. CONCLUSIONS: Arachnoid veil was present in 10% of cases. Radiographic measurements indicating larger syrinx size were the only variables found to be significantly associated with an arachnoid veil. Exploration of the 4th ventricular outlet is recommended for CM-I decompression in the setting of expansile syringomyelia.

Intraoperative neuromonitoring for pediatric Chiari decompression: when is it useful?

OBJECTIVE: Surgical treatment for symptomatic Chiari I malformation involves surgical decompression of the craniovertebral junction. Given the proximity of critical brainstem structures, intraoperative neuromonitoring (IONM) is employed for safe decompression in some institutions. However, IONM adds time and cost to the operation, and the benefit to the patient has not been defined. Given the diversity in surgical practices, there is no evidence-based standard of care regarding when to use IONM and which modalities are most helpful. The purpose of this study was to review a single-surgeon experience with IONM in order to determine the sensitivity, specificity, and predictive values of various IONM modalities routinely used in pediatric Chiari I decompression; to examine the associations between patient, clinical, and radiographic characteristics and IONM alerts; and to obtain data regarding the usefulness of these modalities during the surgical process to improve patient outcomes. METHODS: A retrospective review was performed for 300 consecutive pediatric patients who underwent suboccipital craniectomy and C1 laminectomy for Chiari decompression performed by a single surgeon over a 15-year period. Clinical, radiographic, and IONM data were collected. Radiographic measurements of the skull base morphological abnormalities, including clival angle, Chamberlain's line, and Grabb-Oakes line, were compared between patients with and without true IONM signal changes. RESULTS: A total of 291 cases were included, with an age range of 6 months to 19 years. Among 291 cases, somatosensory evoked potentials (SSEPs) were monitored in 291, motor evoked potentials (MEPs) in 209, cranial nerve spontaneous electromyography (sEMG) in 290, and brainstem auditory evoked potentials (BAEPs) in 110. Sensitivity, specificity, positive predictive value, and negative predictive value, respectively, were as follows: 1.00, 1.00, 1.00, and 1.00 for SSEPs; 1.00, 0.99, 0.67, and 1.00 for MEPs; 0.00, 0.88, 0.00, and 1.00 for sEMG; and not appliable, 1.00, not applicable, and 1.00 for BAEPs. Six patients had true IONM signal changes. These patients had radiographic evidence of more severe concomitant craniocervical instability and basilar invagination, with steeper clival angles (124° vs 146°, p = 0.02) and larger Grabb-Oakes lines (10.1 mm vs 6.7 mm, p = 0.02), when compared with the patients without any true IONM changes. CONCLUSIONS: Intraoperative neuromonitoring may be best utilized for patients who show radiographic features of abnormal skull base morphology, defined as a clival angle < 135° or Grabb-Oakes line > 9 mm. When IONM is employed, SSEP and MEP monitoring are the most useful modalities.

Incidence and management of postoperative pseudomeningocele and cerebrospinal fluid leak after Chiari malformation type I decompression.

OBJECTIVE: The optimal surgical management of Chiari malformation type I (CM-I) remains controversial and heterogeneous. The authors sought to investigate patient-specific, technical, and perioperative features that may affect the incidence of CSF-related complications including pseudomeningocele and CSF leak at their institution. METHODS: The authors performed a single-center, retrospective review of all adult patients with CM-I who underwent posterior fossa decompression. Patient demographics, operative details, and perioperative factors were collected via electronic medical record review. The authors performed Fisher's exact test and independent Student t-tests for categorical and continuous variables, respectively. Univariate regression analysis was performed to determine odds ratios. A multivariable regression analysis was performed for those factors with p < 0.10 or large effect sizes (OR ≥ 2.0 or ≤ 0.50) by univariate analysis. The STROBE guidelines for observational studies were followed. RESULTS: A total of 59 adult patients were included. Most patients were female (78.0%), and the mean body mass index was 32.2 (± 9.0). Almost one-third (30.5%) of patients had a syrinx on preoperative imaging. All patients underwent expansile duraplasty, of which 47 (79.7%) were from autologous pericranium. Arachnoid opening for fourth ventricular inspection was performed in 26 (44.1%) cases. CSF-related complications were identified in 18 (30.5%) of cases. Thirteen (22.0%) patients required readmission and 11 (18.6%) required intervention such as wound revision (n = 5), wound revision with CSF diversion (n = 4), CSF diversion alone (n = 1), or blood patch (n = 1). Three (5.1%) patients required permanent CSF diversion. Male sex (OR 3.495), diabetes mellitus (OR 0.249), tobacco use (OR 2.53), body mass index more than 30 (OR 2.45), preoperative syrinx (OR 1.733), autologous duraplasty (OR 0.331), and postoperative steroids (OR 2.825) were included in the multivariable analysis. No factors achieved significance by univariate or multivariable analysis (all p > 0.05). CONCLUSIONS: The authors report a single-center, retrospective experience of posterior fossa decompression for 59 adults with CM-I. No perioperative or technical features were found to affect the CSF-related complication rate. More standardized practices within centers are necessary to better delineate the true risk factors and potential protective factors against CSF-related complications.

Chiari I malformation in patients with RASopathies.

PURPOSE: Chiari I malformation (CIM) is a common pediatric neurologic anomaly which could be associated with a variety of genetic disorders. However, it is not always clear whether the observed associations between CIM and RASopathies are real or random. The knowledge of the real association could provide useful guidance to clinicians. Furthermore, it could help to better understand the still unknown genetic etiology of CIM. METHOD AND RESULTS: We reviewed the current knowledge of CIM and RASopathies in the paper. Here, we describe one patient with CIM and Noonan syndrome and three patients with CIM and neurofibromatosis type 1. Three of the four patients underwent standard surgical therapy of Chiari decompression and had a straightforward recovery without further complications from surgery. CONCLUSION: In RASopathy, imaging of the nervous system may be necessary. With the increase in availability of magnetic resonance imaging, we believe that there will be a growing body of evidence to suggest that CIM is more commonly seen in RASopathy. Future studies should attempt to elucidate the pathogenic mechanism responsible for CIM mediated by the RAS/MAPK signaling pathway.

Preoperative Acetazolamide Challenge in Pediatric Chiari I Malformation.

PURPOSE: In patients who present with headaches and Chiari 1 malformation without cranial nerve or brainstem dysfunction or syrinx formation, the decision to decompress can be difficult to make. We present a case series examining the use of acetazolamide as a diagnostic aid to determine candidacy for decompression. METHODS: A single pediatric neurosurgeon's (M.M.H.) experience from 2003 to 2018 was retrospectively reviewed. All cases evaluated in the clinic for CPT code of Chiari 1 malformation were analyzed. Inclusion criteria were patients with diagnosis of Chiari 1 malformation and headache-predominant symptoms who underwent an acetazolamide challenge test. Exclusion criteria included age over 18, syrinx, or significant clinical evidence of brainstem compression or cranial nerve dysfunction. Data were recorded with respect to response to acetazolamide. Surgical outcomes were assessed using the Chicago Chiari Outcome Scale (CCOS) pain category and the improve/same/worse (IWS) scale. Overall satisfaction from surgery was also recorded. RESULTS: Forty-five patients met inclusion criteria and underwent acetazolamide challenge. Thirty-three (73.3%) patients showed improvement of their symptoms with acetazolamide challenge (responders). Of the 33 responders, 25 (75.8%) underwent Chiari decompression. The remaining 8 (24.2%) responders experienced persistent improvement of their symptoms after the acetazolamide trial and did not require intervention. Twelve (26.7%) patients did not improve with acetazolamide (nonresponders) of which 11 (91.7% of nonreponders) never required intervention. One nonresponder eventually underwent Chiari decompression due to progressively worsening and debilitating headaches. All twenty-five (100%) responders improved after surgery and 24 (96%) were satisfied with the outcome of surgery. The average responder CCOS pain score was 3.52 out of 4. The nonresponder who did not improve with acetazolamide had persistent severe headaches after decompression. The CCOS pain score for this nonresponder was 2 out of 4. CONCLUSION: Pediatric headache-predominant Chiari 1 malformation presents a difficult diagnostic dilemma. The authors describe a trial of acetazolamide as a preoperative diagnostic tool to aid the decision to decompress. Further studies will need to be performed to determine the effectiveness of preoperative acetazolamide in identifying which patients may benefit from surgical decompression.

Management of failed Chiari decompression and intrasyringeal hemorrhage in Noonan syndrome: illustrative cases.

BACKGROUND: Noonan syndrome (NS) is a rare genetic RASopathy with multisystem implications. The disorder is typically characterized by short stature, distinctive facial features, intellectual disability, developmental delay, chest deformity, and congenital heart disease. NS may be inherited or arise secondary to spontaneous mutations of genes in the Ras/mitogen activated protein kinase signaling pathways. OBSERVATIONS: Numerous case reports exist detailing the association between NS and Chiari I malformation (CM-I), although this relationship has not been fully established. Patients with NS who present with CM-I requiring operation have shown high rates reoperation for failed decompression. The authors reported two patients with NS, CM-I, and syringomyelia who had prior posterior fossa decompressions without syrinx improvement. Both patients received reoperation with successful outcomes. LESSONS: The authors highlighted the association between NS and CM-I and raised awareness that patients with these disorders may be at higher risk for failed posterior fossa decompression, necessitating reoperation.

Chiari decompression for syringomyelia in the setting of IgG4-related hypertrophic pachymeningitis: A case-based update.

Hypertrophic pachymeningitis can lead to clinical brainstem and cervical spinal cord compression leading to neurologic deficits. IgG4-related hypertrophic pachymeningitis (IgG4-RHP) is one recently recognized etiology of previously idiopathic cases. A 34-year-old right-handed female presented with slowly progressive neurologic symptoms and worsening radiographic syringomyelia. She successfully underwent Chiari decompression and excision of her pachymeningitis with improvement in her radiographic findings. Extensive clinical workup has led to a diagnosis of IgG4-RHP and treatment with steroids. IgG4-RHP is a rare cause of spinal cord compression and on our review of the literature this is the first description of significant syringomyelia associated with this condition. This remains a challenging entity to treat and neurology and rheumatology referrals should be placed early to investigate IgG4-RHP as an etiology for idiopathic cases. Treatment of this disease is likely to evolve with further research.

Chiari 1 and Hydrocephalus - A Review.

Chari 1 malformation, a radiologic finding of caudal cerebellar tonsillar displacement, has a clinical course that can range from benign to complications involving life-threatening hydrocephalus. While the pathophysiologic processes underlying this variation in outcome remain a matter of scientific debate, the clinical realities and decision-making conundrums that these patients pose require a coherent approach to this entity. In this review, we seek to highlight the various processes underlying the development of hydrocephalus in patients with Chiari 1 malformations. Hydrocephalus may occur as a cause, consequence, or in parallel with the development of Chiari 1 malformation, and understanding the etiology of such hydrocephalus is critical to the treatment of Chiari 1 malformations with associated hydrocephalus. We further discuss the literature pertaining to the management of these patients and unify the current scientific thinking on Chiari 1 malformations with the extant data on operative management of Chiari 1 to develop a structured and pragmatic approach to the diagnosis and management of patients with Chiari 1-associated hydrocephalus.

Tactile Skill-Based Neurosurgical Simulators Are Effective and Inexpensive.

BACKGROUND: Regulations limit residency work hours and operating time, limiting the amount of hands-on surgical training. To develop alternative hands-on training, many programs teach surgical skills in laboratories and workshops with the use of simulators. The expense of computer simulators and lack of replication of the manual skills and tactile feedback of surgery limit their usefulness. We have developed 2 replicable simulators constructed from low-cost materials, which allow residents to practice the manual skills required in key portions of minimally invasive lumbar decompression and Chiari decompression surgeries. The objective was to review the efficacy of our lumbar and Chiari decompression simulators in improving resident and medical student surgical skills. METHODS: Resident and medical student participants completed one or both simulators 10 times. The lumbar decompression simulations were evaluated by the length of time participants blocked the field of view and by the number of times they lost control of the drill. Chiari decompression simulations were evaluated by the length of time to complete the simulation and by the regularity of their sutures. RESULTS: After 10 attempts, participants of the lumbar decompression simulator decreased the amount of time blocking the field of view by 52% and decreased the number of times they lost control of the drill by 69%. Participants of the Chiari decompression simulator decreased their suturing time by 56% and improved the regularity of their sutures. CONCLUSIONS: The simple and inexpensive simulators evaluated in this study were shown to improve the speed, quality of work, and comfort level of the participants.

PedsQL for prediction of postoperative patient-reported outcomes following Chiari decompression surgery.

OBJECTIVE: The purpose of this study is to determine if the preoperative Pediatric Quality of Life Inventory (PedsQL) score is predictive of short- and intermediate-term PedsQL outcomes following Chiari decompression surgery. The utility of preoperative patient-reported outcomes (PROs) in predicting pain, opioid consumption, and long-term PROs has been demonstrated in adult spine surgery. To the best of the authors' knowledge, however, there is currently no widely accepted tool to predict short-, intermediate-, or long-term outcomes after pediatric Chiari decompression surgery. METHODS: A prospectively maintained database was retrospectively reviewed. Patients who had undergone first-time decompression for symptomatic Chiari malformation were identified and grouped according to their preoperative PedsQL scores: mild disability (score 80-100), moderate disability (score 60-79), and severe disability (score < 60). PedsQL scores at the 6-week, 3-month, and/or 6-month follow-ups were collected. Preoperative PedsQL subgroups were tested for an association with demographic and perioperative characteristics using one-way ANOVA or chi-square analysis. Preoperative PedsQL subgroups were tested for an association with improvements in short- and intermediate-term PedsQL scores using one-way ANOVA and a paired Wilcoxon signed-rank test controlling for statistically different demographic characteristics when appropriate. RESULTS: A total of 87 patients were included in this analysis. According to their preoperative PedsQL scores, 28% of patients had mild disability, 40% had moderate disability, and 32% had severe disability. There was a significant difference in the prevalence of comorbidities (p = 0.009) and the presenting symptoms of headaches (p = 0.032) and myelopathy (p = 0.047) among the subgroups; however, in terms of other demographic or operative factors, there was no significant difference. Patients with greater preoperative disability demonstrated statistically significantly lower PedsQL scores at all postoperative time points, except in terms of the parent-reported PedsQL at 6 months after surgery (p = 0.195). Patients with severe disability demonstrated statistically significantly greater improvements (compared to preoperative scores) in PedsQL scores at all time points after surgery, except in terms of the 6-week and 6-month PROs and the 6-month parent-reported outcomes (p = 0.068, 0.483, and 0.076, respectively). CONCLUSIONS: Patients with severe disability, as assessed by the PedsQL, had lower absolute PedsQL scores at all time points after surgery but greater improvement in short- and intermediate-term PROs. The authors conclude that the PedsQL is an efficient and accurate tool that can quickly assess patient disability in the preoperative period and predict both short- and intermediate-term surgical outcomes.

Duraplasty Type as a Predictor of Meningitis and Shunting After Chiari I Decompression.

BACKGROUND: Expansile duraplasty is frequently performed during Chiari I decompression. Aseptic and bacterial meningitis are possible complications of this procedure. We sought to compare the rates of meningitis and subsequent need for cerebrospinal fluid (CSF) diversion with duraplasty using bovine pericardial (BPC) xenograft and allograft. METHODS: We conducted a retrospective review of 112 patients who underwent Chiari I decompression. All patients underwent duraplasty with either allograft or BPC. Occurrence of postoperative lumbar punctures and associated data were recorded to determine rates of meningitis. Rates of subsequent shunting were also recorded. RESULTS: Overall, 112 patients were included in the study: 30 underwent duraplasty with allograft (27%) and 82 received BPC (73%). A total of 26 patients developed postoperative meningitis (23 cases of chemical meningitis and 3 of bacterial meningitis). Rates of meningitis were higher in patients who received BPC than patients who received allograft (28% vs. 10%, respectively; P = 0.047). The rate of shunting was greater in patients with meningitis compared with patients without meningitis (56.5% vs. 5.75%, respectively; P < 0.0001). Moreover, 13 of the 15 patients (87%) in the BPC cohort who were shunted were found to have meningitis compared with 0 of the 3 shunted patients (0%) in the allograft cohort (P = 0.044). CONCLUSIONS: We found that rates of total meningitis were greater in patients who underwent Chiari I decompression and duraplasty with BPC compared with an allograft. The rate of shunting was significantly higher for patients who developed meningitis after decompression compared with patients without meningitis.

Resolution of Tachyarrhythmia Following Posterior Fossa Decompression Surgery for Chiari Malformation Type I.

INTRODUCTION: Chiari malformation (CM) type I commonly presents with symptoms such as tussive headaches, paresthesias, and, in severe cases, corticobulbar dysfunction. However, patients may present with atypical symptoms lending to the complexity in this patient population. We present a case of a CM patient presenting with atypical cardiac symptoms and arrhythmias, all of which resolved after surgical decompression. CASE DESCRIPTION: A 31-year-old female presented with atypical chest pain, palpitations, tachycardia, headaches, and dizziness for 2 years. Multiple antiarrhythmics and ultimately cardiac ablation procedure proved to be ineffective. Magnetic resonance imaging revealed CM, and the patient ultimately underwent surgical decompression with subsequent resolution of her symptoms. CONCLUSION: The surgical management of CM patients presenting with atypical symptoms can be challenging and often lead to delays in intervention. To our knowledge this is the only reported case of a patient presenting with tachyarrhythmia and atypical chest pain with resolution after Chiari decompression. We believe the dramatic improvement documented in the present case should serve to advance Chiari decompression in CM patients presenting with refractory tachyarrhythmia in whom no other discernable cause has been elucidated. Further studies are needed to better correlate the findings and to hopefully establish a criteria for patients that will likely benefit from surgical decompression.

Adult Tethered Cord Syndrome Following Chiari Decompression.

BACKGROUND: Adult tethered cord syndrome is a rare neurologic disorder that classically presents with back or leg pain, weakness, and urinary dysfunction. Spinal cord tethering has been associated with acquired Chiari malformations. Whereas the effects of tethered cord release on Chiari malformation symptoms have been described previously, we report an unusual case of acquired tethered cord syndrome following Chiari decompression. CASE DESCRIPTION: We report a 68-year-old man with a history of distant T12-level spinal cord injury and 2 weeks of progressive bilateral lower extremity weakness. The patient underwent a T12-L1 laminectomy in 1977, complicated by arachnoiditis and syringomyelia, with eventual placement of a syringopleural shunt. He remained neurologically stable until 2012, when he underwent a suboccipital craniectomy for Chiari decompression for new-onset headache and dysphagia. Ten days later, the patient noted progressive leg weakness and radiographic evidence of spinal cord tethering at the T11-T12 level. A T10-L1 laminectomy and medical facetectomy was undertaken for detethering with postoperative recovery of ambulatory function with assistance. CONCLUSIONS: Our patient exhibited an unusual acquisition of tethered cord syndrome. The tethering of the spinal cord may have been triggered by arachnoid adhesions from initial lumbar surgery 35 years before presentation and subsequently exacerbated by alterations of cerebrospinal fluid dynamics after Chiari decompression. Given the potentially devastating sequelae of tethered cord syndrome, investigation of cerebrospinal fluid flow dynamics may be beneficial before operative intervention in patients with risk factors for a tethered cord who exhibit adult-onset Chiari malformation.

Intracranial hypertension after Chiari decompression resolving after removal of a levonorgestrel-releasing intrauterine device: case report.

Levonorgestrel-releasing intrauterine devices (LIUDs) are thought to release this progestin locally in the uterus to limit side effects. Authors here present a case of treatment-refractory hydrocephalus and pseudomeningocele (PMC), both of which fully resolved after LIUD removal.A 35-year-old woman with an implanted LIUD developed symptomatic PMC and hydrocephalus after suboccipital craniectomy for Chiari malformation type I. Over the next 8 months, she underwent ventriculoperitoneal shunt placement and two attempts at needle decompression of the fluid collection, which did not relieve her symptoms or the PMC, except for a few days at a time. Subsequently, she had her LIUD removed. Three weeks after removal of the LIUD, her symptoms as well as the fluid collection resolved completely without any further intervention. Thus, the increased intracranial pressure and associated persistence of the PMC may be partially attributed to the LIUD.This case indicates that a persistent problem (PMC and intracranial hypertension) that may be associated with the LIUD rapidly resolves after its removal. Implication of LIUDs as the cause of intracranial hypertension is still a matter of controversy. Further studies are needed to evaluate any potential causal relationship between LIUDs and intracranial hypertension, and physicians are advised to consider this scenario in their differential diagnosis.

Chiari-related scoliosis: a single-center experience with long-term radiographic follow-up and relationship to deformity correction.

OBJECTIVE Previous reports have addressed the short-term response of patients with Chiari-related scoliosis (CRS) to suboccipital decompression and duraplasty (SODD); however, the long-term behavior of the curve has not been well defined. The authors undertook a longitudinal study of a cohort of patients who underwent SODD for CRS to determine whether there are factors related to Chiari malformation (CM) that predict long-term scoliotic curve behavior and need for deformity correction. METHODS The authors retrospectively reviewed cases in which patients underwent SODD for CRS during a 14-year period at a single center. Clinical (age, sex, and associated disorders/syndromes) and radiographic (CM type, tonsillar descent, pBC2 line, clival-axial angle [CXA], syrinx length and level, and initial Cobb angle) information was evaluated to identify associations with the primary outcome: delayed thoracolumbar fusion for progressive scoliosis. RESULTS Twenty-eight patients were identified, but 4 were lost to follow-up and 1 underwent fusion within a year. Among the remaining 23 patients, 11 required fusion surgery at an average of 88.3 ± 15.4 months after SODD, including 7 (30%) who needed fusion more than 5 years after SODD. On univariate analysis, a lower CXA (131.5° ± 4.8° vs 146.5° ± 4.6°, p = 0.034), pBC2 > 9 mm (64% vs 25%, p = 0.06), and higher initial Cobb angle (35.1° ± 3.6° vs 22.8° ± 4.0°, p = 0.035) were associated with the need for thoracolumbar fusion. Multivariable modeling revealed that lower CXA was independently associated with a need for delayed thoracolumbar fusion (OR 1.12, p = 0.0128). CONCLUSIONS This investigation demonstrates the long-term outcome and natural history of CRS after SODD. The durability of the effect of SODD on CRS and curve behavior is poor, with late curve progression occurring in 30% of patients. Factors associated with CRS progression include an initial pBC2 > 9 mm, lower CXA, and higher Cobb angle. Lower CXA was an independent predictor of delayed thoracolumbar fusion. Further study is necessary on a larger cohort of patients to fully elucidate this relationship.

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

BACKGROUND: 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). METHODS: 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. RESULTS: The mean overall score was 14.0 over a mean follow-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. CONCLUSIONS: 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.

Postoperative Pain Control with the Fentanyl Patch and Continuous Paravertebral Anesthetic Infusion after Posterior Occipitocervical Junction Surgery.

Postoperative pain is a significant concern for patients who undergo surgery via a midline posterior approach to the occipitocervical junction and spinal axis. The development of the disposable, ambulatory pain pump presents a novel alternative for treatment of postoperative pain. The authors describe a multimodal treatment algorithm for postoperative pain after posterior occipitocervical junction surgery that uses the On-Q pain catheter system (I-Flow Corp., Lake Forest, CA) and a fentanyl patch. The On-Q PainBuster catheter system is a disposable, ambulatory device that allows for continuous anesthetic delivery directly into or adjacent to the wound. On-Q catheters are placed in the nuchal musculature for continuous infusion of 0.5% bupivacaine. The On-Q catheter infusion is continued for three days, and the catheters are then withdrawn. Patients are also provided with a transdermal fentanyl patch at the start of surgery. In regards to complications at our facility, there have been no cases of respiratory depression or arrest postoperatively and no wound infections, but one case of inadvertent subdural placement. The technique described for the use of the fentanyl patch and a continuous anesthetic delivery device in surgery of the occipitocervical junction presents a novel alternative to the current standard of care in pain control after suboccipital decompression.

Preservation of the Myofascial Cuff During Posterior Fossa Surgery to Reduce the Rate of Pseudomeningocele Formation and Cerebrospinal Fluid Leak: A Technical Note.

INTRODUCTION:  Suboccipital craniotomy is a workhorse neurosurgical operation for approaching the posterior fossa but carries a high risk of pseudomeningocele and cerebrospinal fluid (CSF) leak. We describe our experience with a simple T-shaped fascial opening that preserves the occipital myofascial cuff as compared to traditional methods to reduce this risk. METHODS:  A single institution, retrospective review of prospectively collected database was performed of patients that underwent a suboccipital craniectomy or craniotomy. Patient data was reviewed for craniotomy or craniectomy, dural graft, and/or sealant use as well as CSF complications. A pseudomeningocele was defined as a subcutaneous collection of cerebrospinal fluid palpable clinically and confirmed on imaging. A CSF leak was defined as a CSF-cutaneous fistula manifested by CSF leaking through the wound. All patients underwent regular postoperative visits of two weeks, one month, and three months. RESULTS:  Our retrospective review identified 33 patients matching the inclusion criteria. Overall, our cohort had a 21% (7/33) rate of clinical and radiographic pseudomeningocele formation with 9% (3/33) requiring surgical revision or a separate procedure. The rate of clinical and radiographic pseudomeningocele formation in the myofascial cuff preservation technique was less than standard techniques (12% and 31%, respectively). Revision or further surgical procedures were also reduced in the myofascial cuff preservation technique vs. the standard technique (6% vs 13%). CONCLUSIONS:  Preservation of the myofascial cuff during posterior fossa surgery is a simple and adoptable technique that reduces the rate of pseudomeningocele formation and CSF leak as compared with standard techniques.

High long-term symptomatic recurrence rates after Chiari-1 decompression without dural opening: a single center experience.

OBJECTIVE: We evaluated long-term outcomes of posterior fossa decompression (PFD) without duroplasty in consecutive patients with newly diagnosed Chiari-1 malformation. METHODS: We searched the institutional database for all adult patients who underwent Chiari decompression between 1995 and 2007. PFD was offered to all consecutive patients with Chairi-1 malformation during this time period. We excluded patients who underwent re-exploration after initial Chiari-1 decompression elsewhere. Besides the demographic variables, presenting symptoms, neurological and radiographic findings the clinical records were studied for long-term outcomes specifically symptomatic improvement. We defined symptomatic improvement as resolution of all presenting symptoms including pain and/or neurological deficits at the last follow-up. The factors associated with symptom recurrence were also analyzed. RESULTS: We identified 47 patients who underwent PFD for Chiari-1 malformation. Syringomyelia was noted in 36.2% of patients and the mean tonsilar herniation was 12.6mm. At a mean follow-up of 9.3 years, the symptomatic improvement rate was 60.6%. There were no operative complications. Repeat posterior fossa decompression was required for 31.9% patients with symptomatic recurrence at an average of 2.6 years after initial decompression. Fibrotic thickening overlying the dura mater was observed in one-third of these patients. CONCLUSIONS: This case series reports low complication but high long-term symptomatic recurrence rates adults with symptomatic Chiari-1 malformation undergoing PFD.

Persistent/Recurrent syringomyelia after Chiari decompression-natural history and management strategies: a systematic review.

Study Design Systematic review. Study Rationale One of the most consistent indications for a Chiari decompression is tonsillar descent meeting the radiographic criteria and an associated syrinx in a symptomatic patient. In counseling patients about surgery, it would be advantageous to have information regarding the expected outcome with regard to the syrinx and other possible treatments available if the result is suboptimal. Clinical Questions The clinical questions include: (1) What is the average rate of recurrent or residual syringomyelia following posterior fossa decompression as a result of Chiari malformation with associated syringomyelia? (2) What treatment methods have been reported in the literature for managing recurrent or residual syringomyelia after initial posterior fossa decompression? Materials and Methods Available search engines were utilized to identify publications dealing with recurrent or residual syrinx after Chiari decompression and/or management of the syrinx. Rates of residual or recurrent syrinx were extracted and management strategies were recorded. Overall strength of evidence was quantified. Results Of the 72 citations, 11 citations met inclusion criteria. Rates of recurrent/residual syringomyelia after decompression in adults range from 0 to 22% with an average of 6.7%. There were no studies that discussed specifically management of the remaining syrinx. Conclusion Rates of recurrent/residual syringomyelia after Chiari decompression in adults range from 0 to 22% (average 6.7%). Although no studies describing the optimal management of residual syrinx were found, there is general agreement that the aim of the initial surgery is to restore relatively unimpeded flow of cerebrospinal across the craniocervical junction. Large holocord syrinx may induce a component of spinal cord injury even with adequate decompression and reduction in the caliber of the syrinx, resulting in permanent symptoms of injury.