Albert Lam

Effects of Therapy in X-Linked Hypophosphatemic Rickets

BACKGROUNDnPatients with X-linked hypophosphatemic rickets, which is clinically manifested by growth failure and bowing of the legs, are usually treated with phosphate and a vitamin D preparation. However, the efficacy of this treatment has been disputed, and nephrocalcinosis is a recognized complication of therapy.nnnMETHODSnWe studied 24 patients with X-linked hypophosphatemic rickets (9 boys and 15 girls) ranging in age from 1 to 16 years (median, 5.3). The duration of combination therapy ranged from 0.3 to 11.8 years (median, 3.0). We measured height as a standard-deviation (SD) score (the number of SDs from the mean height for chronologic age). Measurements made before the age of two years or after the onset of puberty were excluded. We compared the results with those reported in 1971 for 16 untreated prepubertal Australian patients. We also determined the severity of nephrocalcinosis (on a scale of 0 to 4, with 0 indicating no abnormalities and 4 stone formation) with renal ultrasonography and whether it could be related to the dosage of phosphate or vitamin D or to other factors.nnnRESULTSnPatients treated for at least two years before the onset of puberty (n = 19) had a mean height SD score of -1.08, as compared with -2.05 in the untreated historical controls. The 13 patients who had been treated with calcitriol and phosphate for at least two years had an increase in the mean height SD score of 0.33, from -1.58 to -1.25 (95 percent confidence interval, 0 to 0.67; P = 0.05). Nineteen of the 24 patients (79 percent) had nephrocalcinosis detected on renal ultrasonography. The grade of nephrocalcinosis was significantly correlated with the mean phosphate dose (r = 0.60, P = 0.002), but not with the dose of vitamin D or the duration of therapy. All patients had normal serum creatinine concentrations.nnnCONCLUSIONSnTherapy with calcitriol and phosphate may increase the growth of children with X-linked hypophosphatemic rickets. Nephrocalcinosis in these children represents a complication of therapy and is associated with the dose of phosphate received.

Measurement of midfemoral shaft geometry: Repeatability and accuracy using magnetic resonance imaging and dual-energy X-ray absorptiometry

Although macroscopic geometric architecture is an important determinant of bone strength, there is limited published information relating to the validation of the techniques used in its measurement. This study describes new techniques for assessing geometry at the midfemur using magnetic resonance imaging (MRI) and dual‐energy X‐ray absorptiometry (DXA) and examines both the repeatability and the accuracy of these and previously described DXA methods. Contiguous transverse MRI (Philips 1.5T) scans of the middle one‐third femur were made in 13 subjects, 3 subjects with osteoporosis. Midpoint values for total width (TW), cortical width (CW), total cross‐sectional area (TCSA), cortical cross‐sectional area (CCSA), and volumes from reconstructed three‐dimensional (3D) images (total volume [TV] and cortical volume [CVol]) were derived. Midpoint TW and CW also were determined using DXA (Lunar V3.6, lumbar software) by visual and automated edge detection analysis. Repeatability was assessed on scans made on two occasions and then analyzed twice by two independent observers (blinded), with intra‐ and interobserver repeatability expressed as the CV (CV ± SD). Accuracy was examined by comparing MRI and DXA measurements of venison bone (and Perspex phantom for MRI), against “gold standard” measures made by vernier caliper (width), photographic image digitization (area) and water displacement (volume). Agreement between methods was analyzed using mean differences (MD ± SD%). MRI CVs ranged from 0.5 ± 0.5% (TV) to 3.1 ± 3.1% (CW) for intraobserver and 0.55 ± 0.5% (TV) to 3.6 ± 3.6% (CW) for interobserver repeatability. DXA results ranged from 1.6 ± 1.5% (TW) to 4.4 ± 4.5% (CW) for intraobserver and 3.8 ± 3.8% (TW) to 8.3 ± 8.1% (CW) for interobserver variation. MRI accuracy was excellent for TV (3.3 ± 6.4%), CVol (3.5 ± 4.0%), TCSA (1.8 ± 2.6%), and CCSA (1.6 ± 4.2%) but not TW (4.1 ± 1.4%) or CW (16.4 ± 14.9%). DXA results were TW (6.8 ± 2.7%) and CW (16.4 ± 17.0%). MRI measures of geometric parameters of the midfemur are highly accurate and repeatable, even in osteoporosis. Both MRI and DXA techniques have limited value in determining cortical width. MRI may prove valuable in the assessment of surface‐specific bone accrual and resorption responses to disease, therapy, and variations in mechanical loading.

Outcomes in persistent hyperplastic primary vitreous.

Aims: To report outcomes in cases of persistent hyperplastic primary vitreous (PHPV) and examine factors predictive of visual acuity in patients selected for surgery. Methods: Retrospective case series of 55 eyes in 50 patients presenting between 1990 and 2001 at the Children’s Hospital, Westmead. 33 eyes underwent surgery aimed at visual rehabilitation. Results: In surgical patients, median age at surgery was 77 days, and median age at final follow up was 28 months. Six (18%) achieved a visual acuity at final follow up of 6/60 or better and eight (24%) achieved acuity of less than 6/60 to counting finger vision inclusive. Those undergoing surgery before 77 days were approximately 13 times more likely to obtain a visual acuity of counting fingers or better than those operated later (pu200a=u200a0.01). Neither posterior segment PHPV nor post-surgical glaucoma was a significant predictor of outcome in this selected group. Conclusion: Early surgery aimed at rehabilitation markedly improves the likelihood of useful visual outcome in selected eyes with PHPV.

Pre-eclampsia: a predisposing factor for neonatal venous sinus thrombosis?

Neonatal venous sinus thrombosis is a well-recognized, but infrequently diagnosed, cause of neonatal encephalopathy. Previous reports have tended to omit reference to the importance of maternal factors in predisposing the infant to this condition. This report, in which eight patients with neonatal venous sinus thrombosis are presented, will reveal a strong association between pre-eclampsia, prothrombotic disorders, and neonatal venous sinus thrombosis. Contrary to previously published reports, there is a high likelihood of neurodevelopmental residua after this condition.

Spontaneous occlusion of post-traumatic splenic pseudoaneurysm: report of two cases in children

Conservative therapy for splenic injuries is widely advocated. The advantages of conservative therapy for splenic injuries include the preservation of splenic immune function, prevention of overwhelming post-splenectomy sepsis, and avoidance of laparotomy and its associated early and late complications. Pseudoaneurysms of the splenic artery branch are encountered because of the prevalence of conservative management and widespread use of imaging techniques in the follow-up of these cases. We report two cases of post-traumatic splenic pseudoaneurysm in children which thrombosed spontaneously, one during the diagnostic angiogram examination and another on follow-up studies.

Intrahepatic bile duct dilatation and cholestasis in autosomal recessive polycystic kidney disease : demonstration with hepatobiliary scintigraphy

Fifteen patients with the clinical and radiologic features of autosomal recessive polycystic kidney disease were investigated with radionuclide hepatobiliary scintigraphy. In nine patients (60%), cholestasis and intrahepatic bile duct dilatation were demonstrated. A 10th child had scintigraphic evidence of cholestasis, but the bile ducts were not dilated. The other five children had normal hepatobiliary scans. The authors conclude that intrahepatic bile duct dilatation with cholestasis (Carolls disease) Is part of the clinical spectrum of autosomal recessive polycystic kidney disease and that hepatobiliary scintigraphy can be of value in determining the extent of hepatobiliary disease in this group of patients.

Symptomatic third ventricular choroid plexus cysts.

We describe the imaging findings in 3 children with choroid plexus cysts (CPC) at the foramen of Monro. All CPC measured less than 2 cm and produced symptoms of raised intracranial pressure when located at the foramen of Monro where there was obstruction to the cerebrospinal fluid (CSF) flow. Among the imaging studies done on our patients, CPC were depicted best by cranial sonography and CT-ventriculography and missed by standard CT and MRI. Misdiagnosis can lead to inappropriate shunting with adverse effects. Two of our patients had relief of symptoms after resection of the cyst. One patient with inoperable cardiac defects died and had no surgery performed. Serial CT and sonographic studies in this patient showed progression in the size of the cyst and ventriculomegaly. Cranial sonography and CT-ventriculography are the modalities of choice in evaluating ventriculomegaly when the diagnosis of occult obstructive CPC is entertained in children. Cranial sonography is indicated in infants with an open fontanelle and CT-ventriculography is reserved for older children with hydrocephalus which is not responding to shunting.

Antenatal prediction of hypertrophic pyloric stenosis

Abstract. This is the first reported case where the diagnosis of hypertrophic pyloric stenosis (HPS) was entertained in the antenatal period and the neonate was followed up in the postnatal period on a prospective basis until the HPS became manifest.

Familial megacalyces with autosomal recessive inheritance (report of 3 affected siblings

Three children with bilateral congenital megacalyces from a consanguinous marriage are reported. No renal abnormality was detected in the parents. Our observation supports the genetic nature of the disease. The ultrasonographic features of congenital megacalyces are described.

Association between p.Leu54Met Polymorphism at the Paraoxonase-1 Gene and Plantar Fascia Thickness in Young Subjects with Type 1 Diabetes

OBJECTIVE— In type 1 diabetes, plantar fascia, a collagen-rich tissue, is susceptible to glycation and oxidation. Paraoxonase-1 (PON1) is an HDL-bound antioxidant enzyme. PON1 polymorphisms have been associated with susceptibility to macro- and microvascular complications. We investigated the relationship between plantar fascia thickness (PFT) and PON1 gene variants, p.Leu54Met, p.Gln192Arg, and c.-107C>T, in type 1 diabetes. RESEARCH DESIGN AND METHODS—This was a cross-sectional study of 331 adolescents with type 1 diabetes (162 male and 169 female). PFT was assessed by ultrasound, PON1 was assessed by genotyping with PCR and restriction fragment–length polymorphism, and serum PON1 activity was assessed by rates of hydrolysis of paraoxon and phenylacetate. RESULTS—Median (interquartile range) age was 15.4 (13.5–17.3) years, and diabetes duration was 7.6 (4.9–10.6) years. The distribution of p.Leu54Met genotypes was LL 135 (40.8%), ML 149 (45%), and MM 47 (14.2%). PFT was abnormal (>1.7 mm) in 159 adolescents (48%). In multivariate analysis, predictors of abnormal PFT were ML/LL versus MM p.Leu54Met polymorphism (odds ratio 3.84 [95% CI 1.49–9.82], P = 0.005); BMI (percentile) (1.02 [1.01–1.03], P = 0.007); systolic blood pressure (percentile) (1.01 [1.00–1.02], P = 0.03); and male sex (3.29 [1.98–5.46], P < 0.001). CONCLUSIONS—Thickening of the plantar aponeurosis occurs predominantly in overweight and male adolescents with type 1 diabetes. The MM genotype at PON1 p.Leu54Met is associated with a reduced risk of abnormal PFT.