Faculty Bibliography

OBJECTIVE Administrative billing data may facilitate large-scale assessments of treatment outcomes for pediatric Chiari malformation Type I (CM-I). Validated International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code algorithms for identifying CM-I surgery are critical prerequisites for such studies but are currently only available for adults. The objective of this study was to validate two ICD-9-CM code algorithms using hospital billing data to identify pediatric patients undergoing CM-I decompression surgery. METHODS The authors retrospectively analyzed the validity of two ICD-9-CM code algorithms for identifying pediatric CM-I decompression surgery performed at 3 academic medical centers between 2001 and 2013. Algorithm 1 included any discharge diagnosis code of 348.4 (CM-I), as well as a procedure code of 01.24 (cranial decompression) or 03.09 (spinal decompression or laminectomy). Algorithm 2 restricted this group to the subset of patients with a primary discharge diagnosis of 348.4. The positive predictive value (PPV) and sensitivity of each algorithm were calculated. RESULTS Among 625 first-time admissions identified by Algorithm 1, the overall PPV for CM-I decompression was 92%. Among the 581 admissions identified by Algorithm 2, the PPV was 97%. The PPV for Algorithm 1 was lower in one center (84%) compared with the other centers (93%-94%), whereas the PPV of Algorithm 2 remained high (96%-98%) across all subgroups. The sensitivity of Algorithms 1 (91%) and 2 (89%) was very good and remained so across subgroups (82%-97%). CONCLUSIONS An ICD-9-CM algorithm requiring a primary diagnosis of CM-I has excellent PPV and very good sensitivity for identifying CM-I decompression surgery in pediatric patients. These results establish a basis for utilizing administrative billing data to assess pediatric CM-I treatment outcomes.

Endoscopic third ventriculostomy with choroid plexus cauterization (ETV/CPC) as a primary treatment for hydrocephalus is gaining popularity in North America, particularly among the infant population. Unfortunately, despite considerable experience with ETV/CPC at several centers, treatment failures still exist. Early reports have suggested that greater than 90 % cauterization of the choroid plexus is associated with improved clinical outcomes. However, individual patient anatomy and smaller overall ventricular size can limit the amount of choroid plexus cauterization that is technically possible through a single frontal burr hole. Furthermore, the degree of cauterization achieved by surgeons using this technique is difficult to quantify objectively. In this report, we describe the case of an infant who failed initial ETV/CPC but then had successful resolution of hydrocephalus after additional choroid plexus cauterization performed through bilateral occipital burr holes. The child remains shunt-free over a year after treatment, suggesting that this three-pronged CPC approach (the "bowling ball" technique) may be successful in some young children with persistent hydrocephalus after ETV/CPC from a single frontal burr hole.

INTRODUCTION/BACKGROUND:Syrinx has been reported in 25-85 % of children with Chiari malformation type I (CMI), and it is most commonly cervical in location. As a result, cervical MRI is routinely included in an evaluation for CMI. Isolated thoracic syrinx without involvement of the cervical cord in this population is uncommon but clinically important because its presence may influence the decision to operate, surgical techniques employed, or interpretation of follow-up imaging. The purpose of this study was to determine the incidence of isolated thoracic syrinx in a large group of children evaluated for CMI. METHODS:We retrospectively reviewed all patients under 21 years of age who were evaluated for CMI at Columbia University/Morgan Stanley Children's Hospital of New York from 1998 to 2013. All patients underwent MRI of the entire spine as part of the CMI evaluation, regardless of whether surgery was planned. The proportion of patients exhibiting isolated thoracic syrinx was determined. Presenting signs, symptoms, and imaging findings were then studied in an attempt to identify any clinical features associated with isolated thoracic syrinx. RESULTS:We identified 266 patients evaluated over the study period. One-hundred thirty-two patients (50 %) presented with a syrinx, and 12 patients (4.5 % of all patients evaluated and 9.1 % of all patients with a syrinx) had an isolated thoracic syrinx. Demographic variables, clinical presentation, and extent of tonsillar ectopia showed great heterogeneity in this group, and no factor was consistently associated with isolated thoracic syrinx. CONCLUSIONS:Isolated thoracic syrinx is an uncommon but clinically significant finding in children with CMI. Our data demonstrate that the presence of a CMI-related thoracic syrinx cannot be reliably predicted clinically and is therefore likely to be missed in patients who do not undergo complete spinal cord imaging. MRI of the entire spinal cord should be considered for all children undergoing initial evaluation for CMI.

OBJECT The long-term consequences of atlantoaxial (AA) and occipitocervical (OC) fusion and instrumentation in young children are unknown. Anecdotal reports have raised concerns regarding altered growth and alignment of the cervical spine after surgical intervention. The purpose of this study was to determine the long-term effects of these surgeries on the growth and alignment of the maturing spine. METHODS A multiinstitutional retrospective chart review was conducted for patients less than or equal to 6 years of age who underwent OC or AA fusion with rigid instrumentation at 9 participating centers. All patients had at least 3 years of clinical and radiographic follow-up data and radiographically confirmed fusion. Preoperative, immediate postoperative, and most recent follow-up radiographs and/or CT scans were evaluated to assess changes in spinal growth and alignment. RESULTS Forty children (9 who underwent AA fusion and 31 who underwent OC fusion) were included in the study (mean follow-up duration 56 months). The mean vertical growth over the fused levels in the AA fusion patients represented 30% of the growth of the cervical spine (range 10%-50%). Three different vertical growth patterns of the fusion construct developed among the 31 OC fusion patients during the follow-up period: 1) 16 patients had substantial growth (13%-46% of the total growth of the cervical spine); 2) 9 patients had no meaningful growth; and 3) 6 patients, most of whom presented with a distracted atlantooccipital dislocation, had a decrease in the height of the fused levels (range 7-23 mm). Regarding spinal alignment, 85% (34/40) of the patients had good alignment at follow-up, with straight or mildly lordotic cervical curvatures. In 1 AA fusion patient (11%) and 5 OC fusion patients (16%), we observed new hyperlordosis (range 43°-62°). There were no cases of new kyphosis or swan-neck deformity, evidence of subaxial instability, or unintended subaxial fusion. No preoperative predictors of these growth patterns or alignment were evident. CONCLUSIONS These results demonstrate that most young children undergoing AA and OC fusion with rigid internal fixation continue to have good cervical alignment and continued growth within the fused levels during a prolonged follow-up period. However, some variability in vertical growth and alignment exists, highlighting the need to continue close long-term follow-up.

OBJECT Chiari malformation Type I (CM-I) is associated with a syrinx in 25%-85% of patients. Although posterior fossa decompression (PFD) without dural opening is an accepted treatment option for children with symptomatic CM-I, many surgeons prefer to open the dura if a syrinx exists. The purpose of this study was to investigate the frequency and timing of syrinx resolution in children undergoing PFD without dural opening for CM-I. METHODS A retrospective review of 68 consecutive pediatric patients with CM-I and syringomyelia who underwent PFD without dural opening was conducted. Patient demographics, presenting symptoms and signs, radiographic findings, and intraoperative ultrasound and neuromonitoring findings were studied as well as the patients' clinical and radiographic follow-up. RESULTS During the mean radiographic follow-up period of 32 months, 70% of the syringes improved. Syrinx improvement occurred at a mean of 31 months postoperatively. All patients experienced symptom improvement within the 1st year, despite only 26% of patients showing radiographic improvement during that period. Patients presenting with sensory symptoms or motor weakness had a higher likelihood of having radiographic syrinx improvement postoperatively. CONCLUSIONS In children with CM-I and a syrinx undergoing PFD without dural opening, syrinx resolution occurs in approximately 70% of patients. Radiographic improvement of the syrinx is delayed, but this does not correlate temporally with symptom improvement. Sensory symptoms or motor weakness on presentation are associated with syrinx resolution after surgery.