Chester K. Yarbrough, Alexander K. Powers, Tae Sung Park, Jeffrey R. Leonard, David D. Limbrick and Matthew D. Smyth
A subset of patients with Chiari malformation Type I (CM-I) presented with acute onset of a neurological deficit. In this study the authors summarize their experience with these patients' clinical presentation, imaging results, timing of surgery, and outcome following decompression.
The authors reviewed clinical records, imaging studies, and operative notes from all patients undergoing posterior fossa decompression for CM-I at St. Louis Children's Hospital from 1990 to 2008. Of the 189 patients who underwent surgery, 6 were identified with the acute onset of a neurological deficit at presentation.
All 6 children (age range 3–14 years, 3 boys and 3 girls) had either syringomyelia (5 patients) or T2 signal changes in the spinal cord (1 patient) and CM-I on initial MR imaging. Three patients presented after minor trauma (1 with paraparesis, 2 with sensory deficits). Three patients presented without a clear history of trauma (1 with abrupt onset of spontaneous dysphagia and ataxia, 2 with sensory deficits). Decompression was performed at a mean 7.7 ± 4.9 days after symptom onset (7.0 ± 1.6 days after neurosurgical evaluation). In 1 patient, symptoms had resolved by the time of surgery; in the remainder of the patients, clear improvements were noted within 2 weeks of surgery, with complete resolution of symptoms by 12 months postoperatively. Follow-up MR images were obtained in 4 patients, demonstrating improvement in the extent of the syrinx in each patient.
Children with CM-I and syringomyelia can develop acute spinal cord or bulbar deficits with relatively minor head or neck injuries. The prognosis for symptomatic improvement in the observed deficit is good, with each patient in our series showing resolution of deficits over time. However, based on this relatively limited experience, the authors suggest that patients who present with an acute neurological deficit and are found to have CM-I be managed with early posterior fossa decompression. Patients with CM-I and syringomyelia may be at higher risk of acute neurological deficit than those without a syrinx.
David D. Limbrick Jr., Prithvi Narayan, Alexander K. Powers, Jeffrey G. Ojemann, Tae Sung Park, Mary Bertrand and Matthew D. Smyth
Hemispherotomy generally is performed in hemiparetic patients with severe, intractable epilepsy arising from one cerebral hemisphere. In this study, the authors evaluate the efficacy of hemispherotomy and present an analysis of the factors influencing seizure recurrence following the operation.
The authors performed a retrospective review of 49 patients (ages 0.2–20.5 years) who underwent functional hemispherotomy at their institution. The first 14 cases were traditional functional hemispherotomies, and included temporal lobectomy, while the latter 35 were performed using a modified periinsular technique that the authors adopted in 2003.
Thirty-eight of the 49 patients (77.6%) were seizure free at the termination of the study (mean follow-up 28.6 months). Of the 11 patients who were not seizure free, all had significant improvement in seizure frequency, with 6 patients (12.2%) achieving Engel Class II outcome and 5 patients (10.2%) achieving Engel Class III. There were no cases of Engel Class IV outcome. The effect of hemispherotomy was durable over time with no significant change in Engel class over the postoperative follow-up period. There was no statistical difference in outcome between surgery types. Analysis of factors contributing to seizure recurrence after hemispherotomy revealed no statistically significant predictors of treatment failure, although bilateral electrographic abnormalities on the preoperative electroencephalogram demonstrated a trend toward a worse outcome.
In the present study, hemispherotomy resulted in freedom from seizures in nearly 78% of patients; worthwhile improvement was demonstrated in all patients. The seizure reduction observed after hemispherotomy was durable over time, with only rare late failure. Bilateral electrographic abnormalities may be predictive of posthemispherotomy recurrent seizures.
Chester K. Yarbrough, Jacob K. Greenberg, Matthew D. Smyth, Jeffrey R. Leonard, Tae Sung Park and David D. Limbrick Jr.
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.
James M. Johnston Jr., Francesco T. Mangano, Jeffrey G. Ojemann, Tae Sung Park, Edwin Trevathan and Matthew D. Smyth
The purpose of this study was to better define the incidence of complications associated with placement of subdural electrodes for localization of seizure foci and functional mapping in children.
The authors retrospectively reviewed the records of 112 consecutive patients (53 boys, 59 girls; mean age 10.9 years, range 10 months–21.7 years) with medically intractable epilepsy who underwent invasive monitoring at the Pediatric Epilepsy Center at St. Louis Children’s Hospital between January 1994 and July 2005. There were 122 implantation procedures (85 grids and strips, 32 strips only, five grids only, four with additional depth electrodes), with a mean monitoring period of 7.1 days (range 2–21 days). Operative complications included the need for repeated surgery for additional electrode placement (5.7%); wound infection (2.4%); cerebrospinal fluid leak (1.6%); and subdural hematoma, symptomatic pneumocephalus, bone flap osteomyelitis, and strip electrode fracture requiring operative retrieval (one patient [0.8%] each). There were four cases of transient neurological deficit (3.3%) and no permanent deficit or death associated with invasive monitoring.
Placement of subdural grid and strip electrodes for invasive video electroencephalographic monitoring is generally well tolerated in the pediatric population. The authors found that aggressive initial electrode coverage was not associated with higher rates of blood transfusion or perioperative complications, and reduced the frequency of repeated operations for placement of supplemental electrodes.
Francesco T. Mangano, Jose A. Menendez, Matthew D. Smyth, Jeffrey R. Leonard, Prithvi Narayan and Tae Sung Park
All-terrain vehicles (ATVs) have been characterized as inherently unstable and are associated with significant pediatric injuries in the US. The authors performed a study to analyze data obtained in pediatric patients who had sustained neurological injuries in ATV-related accidents, identify potential risk factors, and propose preventive measures. The study is based on a 10-year experience at the St. Louis Children’s Hospital.
The authors retrospectively analyzed data obtained in all patients admitted to the St. Louis Children’s Hospital between 1993 and 2003, limiting their focus to pediatric cases involving ATV-related accidents. A total of 185 patients were admitted with these criteria. Sixty-two patients (33.5%) suffered neurological injuries; there were 42 male and 20 female patients whose age ranged from 2 to 17 years. The most common injuries included skull fracture (37 cases) and closed head injury (30 cases). There were 39 cases of intracranial hemorrhage and 11 of spinal fracture. A total of 15 types of neurosurgical procedure were performed: six craniotomies for hematoma drainage, five craniotomies for elevation of depressed fractures, two procedures to allow placement of an intracranial pressure monitor, one to allow placement of an external ventricular drain, and one to allow the insertion of a ventriculoperitoneal shunt. Two patients had sustained spinal cord injury, and three procedures were performed for spinal decompression or stabilization. The duration of hospital stay ranged from 1 to 143 days (mean 6.6 days). Fifty-seven patients (30.8%) were eventually discharged from the hospital, three (1.6%) were transferred to another hospital, two (1.1%) died, and 123 (66.4%) required in-patient rehabilitation.
Children suffered significant injuries due to ATV accidents. In passengers there was a statistically significant increased risk of neurological injury. The relative risk of neurological injury in patients not wearing helmets was higher than that in those who wore helmets, but the difference did not reach statistical significance. Further efforts must be made to improve the proper operation and safety of ATVs, both through the education of parents and children and through the creation of legislation requiring stricter laws concerning ATV use.
Francesco T. Mangano, Jose A. Menendez, Tracy Habrock, Prithvi Narayan, Jeffrey R. Leonard, Tae Sung Park and Matthew D. Smyth
The use of adjustable differential pressure valves has been recommended to improve ventriculoperitoneal (VP) shunt performance in selected patients; however, published data are scarce regarding their clinical reliability. Recently, the identification of a number of malfunctioning programmable valves during shunt revision surgery in children prompted a retrospective review of valve performance in this patient cohort.
The authors performed a retrospective chart analysis of 100 patients with programmable valve shunts and 89 patients with nonprogrammable valve shunts implanted at the St. Louis Children's Hospital between April 2002 and June 2004. They noted the cause of hydrocephalus, the type of shunt malfunction, and cerebrospinal fluid (CSF) protein levels. Regular clinical follow up ranged from 1 to 26 months, with a mean follow-up time of 9.75 months for patients with programmable valves and 10.4 months for patients with nonprogrammable valves.
Patient ages ranged from 2 weeks to 18 years. One hundred patients had 117 programmable valves implanted, and 35 of these patients (35%) underwent shunt revision because of malfunction. The programmable valve itself malfunctioned in nine patients who had undergone shunt revision (11.1%/year of follow up). The nonprogrammable valve group had no valve malfunctions. The overall VP shunt revision rate in the nonprogrammable valve group was 20.2%. No significant differences were identified when CSF protein levels and specific malfunction types were compared within the programmable valve and nonprogrammable valve groups.
In this study the authors demonstrated an annualized intrinsic programmable valve malfunction rate of 11.1%, whereas during the same period no intrinsic valve malfunctions were noted with nonprogrammable valve systems for similar causes of hydrocephalus. The CSF protein levels did not correlate with observed valve malfunction rates. Further evaluation in a prospective, randomized fashion will elucidate specific indications for programmable valve systems and better determine the reliability of these valves in the pediatric population.
William W. Ashley Jr., Robert C. McKinstry, Jeffrey R. Leonard, Matthew D. Smyth, Benjamin C. Lee and Tae Sung Park
The authors examine the use of rapid-sequence magnetic resonance (rsMR) imaging to make the diagnosis of malfunctioning and/or infected shunts in patients with hydrocephalus. Computerized tomography (CT) scanning is usually used in this context because it rapidly acquires high-quality images, yet it exposes pediatric patients to particularly high levels of radiation. Standard MR imaging requires longer image acquisition time, is associated with movement artifact, and, in children, usually requires sedation. Standard MR imaging provides greater structural resolution, yet visualization of ventricular catheters is relatively poor.
The authors analyzed a series of 67 rsMR imaging examinations performed without sedation in pediatric patients with hydrocephalus whose mean age was 4 years at the time of the examination. The mean study duration was 22 minutes. Catheter visualization was good or excellent in more than 75% of studies reviewed, and image quality was good or excellent in more than 60% of studies reviewed. The authors analyzed cancer risk with a model used for atomic bomb survivors. Fifty percent of their patients with hydrocephalus had undergone more than four brain imaging studies (CT or MR imaging) in their lifetimes. For the many patients who had undergone more than 15 studies, the total estimated lifetime attributable cancer mortality risk was calculated to be at least 0.35%.
Rapid-sequence MR imaging yields reliable visualization of the ventricular catheter and offers superior anatomical detail while limiting radiation exposure. The authors' protocol is rapid and each image is acquired separately; therefore, motion artifact is reduced and the need for sedation is eliminated. They recommend the use of rsMR imaging for nonemergent evaluation of pediatric hydrocephalus.
Posthemorrhagic ventricular dilation
Joseph H. Piatt
Jacob K. Greenberg, Eric Milner, Chester K. Yarbrough, Kim Lipsey, Jay F. Piccirillo, Matthew D. Smyth, Tae Sung Park and David D. Limbrick Jr.
Chiari malformation Type I (CM-I) is a common and often debilitating neurological disease. Efforts to improve treatment of CM-I are impeded by inconsistent and limited methods of evaluating clinical outcomes. To understand current approaches and lay a foundation for future research, the authors conducted a systematic review of the methods used in original published research articles to evaluate clinical outcomes in patients treated for CM-I.
The authors searched PubMed, Embase, the Cumulative Index to Nursing and Allied Health Literature, ClinicalTrials.gov, and Cochrane databases to identify publications between January 2003 and August 2013 that met the following criteria: 1) reported clinical outcomes in patients treated for CM-I; 2) were original research articles; 3) included at least 10 patients or, if a comparative study, at least 5 patients per group; and 4) were restricted to patients with CM-I.
Among the 74 papers meeting inclusion criteria, there was wide variation in the outcome methods used. However, all approaches were broadly grouped into 3 categories: 1) “gestalt” impression of overall symptomatic improvement (n = 45 papers); 2) postoperative change in specific signs or symptoms (n = 20); or 3) results of various standardized assessment scales (n = 22). Among standardized scales, 11 general function measures were used, compared with 6 disease-specific tools. Only 3 papers used scales validated in patients with CM-I. To facilitate a uniform comparison of these heterogeneous approaches, the authors appraised articles in multiple domains defined a priori as integral to reporting clinical outcomes in CM-I. Notably, only 7 articles incorporated patient-response instruments when reporting outcome, and only 22 articles explicitly assessed quality of life.
The methods used to evaluate clinical outcomes in CM-I are inconsistent and frequently not comparable, complicating efforts to analyze results across studies. Development, validation, and incorporation of a small number of disease-specific patient-based instruments will improve the quality of research and care of CM-I patients.