Evaluation of bone mineral density after ileocystoplasty in children with and without myelomeningocele

Effect of gastrocystoplasty on height and bone density in children

Introduction:

Gastrointestinal tissue in the urinary tract results in numerous metabolic changes. This study investigates the effects of augmentation gastrocystoplasty on the height and bone mineralization in bladder exstrophy patients.

Aim and Objective:

To analyze the long-term outcome following gastrocystoplasty in terms of height, bone mineral density, acid base changes, and complications.

Materials and Methods:

Cross-sectional study was done after obtaining institutional ethics committee clearance. Inclusion criteria included retrospective analysis of all cases who had undergone gastrocystoplasty since 1992 and prospective analysis of all cases who are undergoing gastrocystoplasty during the study period from June 2008 to December 2010. Exclusion criteria included follow up period of less than 2 years and cases lost to follow up. Indian standard charts were used for anthropometric measurement, and bone density scan of lumbar vertebrae and upper end of femur were done for bone matrix and mineral density.

Results:

A total of 23 patients were included in the study. Out of 23 patients, 16 were males and 7 were females. Mean age at gastrocystoplasty was 8.28 years, and mean follow up period was 60 months. The median pre-augmentation and post-augmentation percentile height and weight were 56, 59 and 59, 61 respectively. Mean bone density value was 0.654.

Conclusion:

Augmentation gastrocystoplasty is a safe and viable option without any adverse effect on height or bone mineral density without altering metabolic or acid base homeostasis.

Update on bone fragility in spina bifida

BACKGROUND CONTEXT

Patients with spina bifida (SB) are at risk for pathological fractures and low bone mineral density (BMD).

PURPOSE AND METHODS

This article reviews the literature and provides a comprehensive overview of how the characteristics of SB and its associated comorbidities intersect with bone fragility to identify possible pathophysiological mechanisms of fractures and low BMD.

RESULTS

Bone fragility occurs early in the life of patients with SB as a result of a disturbance that determines changes in bone shape, quantity, and quality, as poor mineralization reduces bone stiffness. Bone fragility in SB occurs due to local and systemic factors and may be considered a state of impaired bone quality of multifactorial aetiology, with complex interacting influences of neurological, metabolic, and endocrinological origins and the presence of smaller bones. Bone fragility should be evaluated globally according to skeletal age and Tanner staging. The phases of the evolution of Charcot joints seem to intercept the evolution of epiphyseal fractures. Charcot arthropathy in SB may be initiated by the occurrence of repetitive trauma and fractures in epiphyseal and subepiphyseal regions, where there is a deficit of bone mineralization and greater bone mass deficits.

CONCLUSION

Bone fragility in MMC potentially has a multifactorial neuro-endocrinological-metabolic-renal dimension, with smaller bones, lower bone mass, and mineralization deficits affecting bone strength.

Enterocystoplasty: The long-term effects on bone mineral density

BACKGROUND

Studies show that enterocystoplasty has a negative effect on bone mineral density (BMD). The aim of this study was to investigate the long-term impact of enterocystoplasty on BMD. We used dual energy x-ray absorptiometry (DEXA) scans to determine BMD and identify patients with osteopenia and osteoporosis who are at potential long-term risk for fracture.

MATERIALS AND METHODS

We reviewed our database of >200 individuals, who had undergone enterocystoplasty or continent diversion for both neurogenic and non-neurogenic reasons during childhood. We chose to study the non-neurogenic group first for a number of technical reasons, and identified 24 individuals who had undergone the procedure for non-neurogenic reasons, and had more than 15 years of follow-up. In addition we had a control group of 10 individuals born with bladder exstrophy, who had undergone primary closure before the year 2000, without enterocystoplasty. We used DEXA scan T- and Z-scores to identify patients with osteopenia and osteoporosis.

RESULTS

Eleven of 24 patients had normal DEXA scans with normal T- and Z-scores; seven had identifiable osteopenia and increased long-term risk for fracture. Six had osteoporosis; three of whom had reduced glomerular filtration rate (GFR). Eight of the 10 individuals in the control group had a normal DEXA scan.

CONCLUSIONS

Enterocystoplasty during childhood can lead to loss of BMD. This does not seem to be related to the enterocystoplasty alone. It is more pronounced in individuals who have other risk factors, such as reduced GFR. The identification of BMD loss makes it possible to intervene before osteoporosis occurs and leads to pathologic fracture.

Metabolic consequences after urinary diversion

Metabolic disturbances are well-known, but sometimes neglected immediate consequences or late sequelae following urinary diversion (UD) using bowel segments. Whereas subclinical disturbances appear to be quite common, clinically relevant metabolic complications, however, are rare. Exclusion of bowel segments for UD results in loss of absorptive surface for its physiological function. Previous studies demonstrated that at least some of the absorptive and secreting properties of the bowel are preserved when exposed to urine. For each bowel segment typical consequences and complications have been reported. The use of ileal and/or colonic segments may result in hyperchloremic metabolic acidosis, which can be prevented if prophylactic treatment with alkali supplementation is started early. The resection of ileal segments may be responsible for malabsorption of vitamin B12 and bile acids with subsequent neurological and hematological late sequelae as well as potential worsening of the patient's bowel habits. Hence, careful patient and procedure selection, meticulous long-term follow-up, and prophylactic treatment of subclinical acidosis is of paramount importance in the prevention of true metabolic complications.

[Metabolic long-term complications after urinary diversion]

Metabolic long-term complications and consequences after urinary diversion are somewhat neglected. Subclinical metabolic disturbances are quite common; however, complications are rare. The absorptive surface of the bowel segment is lost for the physiological function of the gastrointestinal tract. Some studies demonstrated that at least some of the absorbent and secreting properties of the bowel are preserved if exposed to urine. For each bowel segment typical complications are reported. Using ileal and/or colon segments, hyperchloremic metabolic acidosis may occur. Studies demonstrated that metabolic effects are not as severe as suspected and could be prevented if a prophylactic treatment is started early.The resection of ileal segments is responsible for malabsorption of vitamin B(12) and bile acid; when using colonic segments, electrolyte disturbances are more common. Careful patient selection, meticulous follow-up and prophylactic treatment are crucial to prevent metabolic complications.

Bladder augmentation and urinary diversion in patients with neurogenic bladder: non-surgical considerations

Segments from almost all parts of the bowel have been used for urinary diversion. As a result, the available absorptive surface area of the bowel is reduced, and the incorporation of bowel segments into the urinary tract may have metabolic consequences. This is an area somewhat neglected in the literature. Metabolic complications are rare, but sub-clinical metabolic disturbances are quite common. Several studies have demonstrated that some of the absorbent and secreting properties of the bowel tissue are preserved after incorporation into the urinary tract. Hyperchloraemic metabolic acidosis can occur if ileal and/or colon segments are used, as well as malabsorption of vitamin B(12) and bile acid after the use of ileal segments. These metabolic effects are not as severe as may be suspected and can be prevented by prophylactic substitution. Secondary malignancies can develop as a long-term consequence of bladder augmentation. Using colonic segments, tumours are most likely to occur at the ureteral implantation site. To prevent metabolic complications, careful patient selection and meticulous and lifelong follow up, as well as prophylactic treatment, are mandatory. Endoscopy for early detection has been recommended, starting 10 years postoperatively for patients who underwent surgery for a benign condition.

Osteoporosis in paediatric patients with spina bifida

The prevalence and morbidity associated with osteoporosis and fractures in patients with spina bifida (SB) highlight the importance of osteoporosis prevention and treatment in early childhood; however, the issue has received little attention. The method for the selection of appropriate patients for drug treatment has not been clarified.

OBJECTIVE

To review the literature concerning fracture risks and low bone density in paediatric patients with SB. We looked for studies describing state-of-the-art treatments and for prevention of secondary osteoporosis.

METHODS

Articles were identified through a search in the electronic database (PUBMED) supplemented with reviews of the reference lists of selected papers. The main outcome measures were incidence of fractures and risk factors for fracture, an association between bone mineral density (BMD) and occurrence of fracture, risk factors of low BMD, and effects of pharmacological and non-pharmacological treatments on BMD and on the incidence of fractures. We considered as a secondary outcome the occurrence of fractures in relation to the mechanism of injury.

RESULTS

Results indicated that patients with SB are at increased risk for fractures and low BMD. Risk factors that may predispose patients to fractures include higher levels of neurological involvement, non-ambulatory status, physical inactivity, hypercalciuria, higher body fat levels, contractures, and a previous spontaneous fracture. Limitations were observed in the number and quality of studies concerning osteoporosis prevention and treatment in paediatric patients with SB. The safety and efficiency of drugs to treat osteoporosis in adults have not been evaluated satisfactorily in children with SB.

Exstrophy bladder: Effect of sigmoid colocystoplasty on physical growth and bone mineral density

Background and Aims:

Introduction of intestinal tissue in the urinary tract results in numerous metabolic changes. This study investigates the effects of augmentation sigmoid colocystoplasty on the physical growth and bone mineralization in bladder exstrophy patients.

Materials and Methods:

Physical growth, serum biochemistry and bone mineral density were assessed pre and post augmentation in 34 of 54 patients who were treated by staged sigmoid colocystoplasty for classical bladder exstrophy during the period 1985–2007. Physical growth was determined by comparing the height and weight for age with standard growth charts. Serum biochemistry included calcium, phosphate and alkaline phosphatase levels. Bone mineral density (BMD) was determined at the femoral head using the dual energy X-ray absorptiometry (DEXA) scan at 15 ± 4.5 months after the augmentation. The DEXA scan findings were compared with 22 normal Indian children who served as controls and 18 unaugmented patients with bladder exstrophy. In 13 augmented patients, the DEXA scan could be repeated after an interval of six months.

Results:

The mean percentile height and weight were comparable in the pre and post-augmentation period with no statistically significant difference (P=0.135 for height and P=0.232 for weight). Biochemical parameters of bone metabolism also did not show any statistically significant changes after colocystoplasty. The BMD was 0.665 ± 0.062 g/cm² in the controls and 0.612 ± 0.10 g/cm² in the unaugmented bladder exstrophy patients. In the augmented patients, the BMD was 0.645 ± 0.175 g/cm² and six months later it was 0.657 ± 0.158 g/cm². These differences were not statistically significant.

Conclusions:

In our study, no significant effects on the physical growth and bone mineral metabolism were observed in exstrophy bladder patients following sigmoid colocystoplasty.

Bone mineral density as a marker for the timing of pectus bar removal after Nuss procedure

Bone mineral density (BMD) was measured to establish the optimal timing for pectus bar (PB) removal after the Nuss procedure (NP). Twenty-three patients who had PB removal after NP were assessed according to: age at PB insertion/removal, duration of insertion, clinical outcome and BMD. BMD was measured just prior to insertion (in-BMD) and just prior to removal (out-BMD) and %BMD was determined by dividing subject BMD by BMD for age-matched controls. Age at insertion ranged from 4.3-2.7 years and age at removal ranged from 6.3-14.1 years. Duration of insertion ranged from 1.4-3.9 years. There were two cases of recurrence after NP. In these cases, PB insertion occurred at 5 and 4 years, and removal was at 6 and 8 years respectively and both BMD and %BMD were below normal. In the nine cases with no recurrence, PB removal occurred between 6-8 years old; BMD was normal, and %BMD was higher than in the two cases with recurrence. BMD and %BMD would appear to be valuable markers for the timing of PB removal.

Skeletal health after intestinal bladder augmentation: findings in 54 patients

OBJECTIVE

To evaluate the risk of osteopenia in patients after intestinal bladder augmentation.

PATIENTS AND METHODS

In all, 54 patients with bladder augmentation were evaluated during the regular follow-up programme. Augmentation was performed because of paediatric neurogenic or non-neurogenic reasons. Areal bone mineral densities (aBMD) for the lumbar spine (L1-L4), femoral neck and whole body were measured with dual-energy X-ray absorptiometry. In addition, acid-base balance and plasma 25-hydroxyvitamin D (vitamin D), kidney and gonadal functions as well as body mass index (BMI) were measured. Findings were correlated with clinical characteristics.

RESULTS

BMD was reduced in 34 (63%) of the 54 patients. There was a significant difference in the prevalence of decreased aBMDs between neurogenic and non-neurogenic groups 31 of 42 patients (74%) and three of 12 patients, respectively (P < 0.01). There were spinal compression fractures in 23% of patients. Risk factors for osteoporosis were inability to walk, renal insufficiency, hypogonadism, vitamin D deficiency, acidosis, and a low BMI. There was moderate or severe vitamin D deficiency in 42% of patients but the vitamin D status did not correlate with BMD. The glomerular filtration rate correlated to the whole-body aBMD (P = 0.04). In 26% of patients (predominantly males with myelomeningocele) plasma follicle-stimulating hormone levels were elevated, indicating variable degrees of hypogonadism. Hypogonadism was associated with reduced lumbar spine aBMD (P = 0.03).

CONCLUSION

Patients with paediatric reasons for bladder augmentation are at risk of osteopenia and compression fractures. The risk factors are mostly related to the patient's underlying illness and not to the augmentation per se.