A prospective one-year natural history study of mucopolysaccharidosis types IIIA and IIIB: Implications for clinical trial design.

Mucopolysaccharidosis type III is a group of four autosomal recessive enzyme deficiencies leading to tissue accumulation of heparan sulfate. Central nervous system disease is prominent, with initial normal development followed by neurocognitive decline leading to death. In order to define outcome measures suitable for gene transfer trials, we prospectively assessed disease progression in MPS IIIA and IIIB subjects >2years old at three time points over one year (baseline, 6 and 12months). Fifteen IIIA (9 male, 6 female; age 5.0±1.9years) and ten IIIB subjects (8 male, 2 female; age 8.6±3years) were enrolled, and twenty subjects completed assessments at all time points. Cognitive function as assessed by Mullen Scales maximized at the 2.5 to 3year old developmental level, and showed a significant age-related decline over a 6month interval in three of five subdomains. Leiter nonverbal IQ (NVIQ) standard scores declined toward the test floor in the cohort by 6 to 8years of age, but showed significant mean declines over a 6month interval in those <7years old (p=0.0029) and in those with NVIQ score≥45 (p=0.0313). Parental report of adaptive behavior as assessed by the Vineland-II composite score inversely correlated with age and showed a significant mean decline over 6month intervals (p=0.0004). Abdominal MRI demonstrated increased volumes in liver (mean 2.2 times normal) and spleen (mean 1.9 times normal) without significant change over one year; brain MRI showed ventriculomegaly and loss of cortical volume in all subjects. Biochemical measures included urine glycosaminoglycan (GAG) levels, which although elevated showed a decline correlating with age (p<0.0001) and approached normal values in older subjects. CSF protein levels were elevated in 32% at enrollment, and elevations of AST and ALT were frequent. CSF enzyme activity levels for either SGSH (in MPS IIIA subjects) or NAGLU (in MPS IIIB) significantly differed from normal controls. Several other behavioral or functional measures were found to be uninformative in this population, including timed functional motor tests. Our results suggest that cognitive development as assessed by the Mullen and Leiter-R and adaptive behavior assessment by the Vineland parent interview are suitable functional outcomes for interventional trials in MPS IIIA or IIIB, and that CSF enzyme assay may be a useful biomarker to assess central nervous system transgene expression in gene transfer trials.

Focused abdominal sonography for trauma (FAST) in children with blunt abdominal trauma.

BACKGROUND: Focused abdominal sonography for trauma (FAST) has been well reported in adults, but its applicability in children is less well established. We decided to test the hypothesis that FAST and computed tomography (CT) are equivalent imaging studies in the setting of pediatric blunt abdominal trauma. METHODS: One hundred seven hemodynamically stable children undergoing CT for blunt abdominal trauma were prospectively investigated using FAST. The ability of FAST to predict injury by detecting free intraperitoneal fluid was compared with CT as the imaging standard. RESULTS: Thirty-two patients had CT documented injuries. There were no late injuries missed by CT. FAST detected free fluid in 12 patients. Ten patients had solid organ injury but no free fluid and, thus, were not detected by FAST. The sensitivity of FAST relative to CT was only 0.55 and the negative predictive value was only 0.50. CONCLUSION: FAST has insufficient sensitivity and negative predictive value to be used as a screening imaging test in hemodynamically stable children with blunt abdominal trauma.

Preliminary experience with focused abdominal sonography for trauma (FAST) in children: is it useful?

BACKGROUND/PURPOSE: Most pediatric surgeons and pediatric radiologists consider computed tomography (CT) the best radiological test for the evaluation of children with suspected intraabdominal injury. The majority of injured children evaluated with CT will be found to have a normal scan. Focused abdominal sonography for trauma (FAST) has been shown to be a useful screening test in the evaluation of adult patients with suspected intraabdominal injury. Limited data exist regarding the use of FAST in children. Our aim was to evaluate the usefulness of FAST as a screening test in the evaluation of children with suspected intraabdominal injury in an attempt to minimize the number of normal CT scans performed. METHODS: Hemodynamically stable children evaluated for suspected intraabdominal injury were prospectively screened with FAST. FAST, real-time sonography at four sites, was performed by staff pediatric radiologists. The average duration of the examination was 2 minutes. Positive and negative FAST scan findings were defined prospectively. The result of each FAST was recorded (positive or negative) and then all patients underwent CT as a control. All management decisions were based on CT results. RESULTS: Forty-six patients were included in the study. FAST identified four children with positive findings (free intraperitoneal fluid), whereas CT showed 13 children with injuries (nine with associated free intraperitoneal fluid and four with only solid organ injury and no associated intraperitoneal fluid). There were nine false-negative and no false-positive FAST scans. The sensitivity of FAST was 0.3 and the specificity was 1.0. Injuries missed by FAST included liver laceration, adrenal hematoma, renal laceration, small bowel injury and splenic laceration. CONCLUSION: Preliminary results suggest that FAST alone is not a useful screening test in the evaluation of children with suspected intraabdominal injury.