Nocturnal polyuria and antidiuretic hormone levels in spinal cord injury

Nocturia and obstructive sleep apnea in spinal cord injured patients - a cohort study

PURPOSE

To describe the prevalence of nocturia and obstructive sleep apnea (OSA) in a cohort of spinal cord injury (SCI) patients and to describe their association. Additionally, to assess clinical and urodynamic data explaining nocturia and to evaluate the effect of OSA management with continuous positive airway pressure (CPAP).

METHOD

Retrospective analysis of data from patients with SCI followed in a tertiary care rehabilitation center with a specialized sleep and neuro-urology units. All adult SCI patients who underwent urodynamic assessment before polysomnography (PSG) between 2015 and 2023 were eligible. Subjective (nocturia) and objective data (urodynamic data, polysomnography, CPAP built-in software) were collated from the Handisom database (database register no. 20200224113128) and the medical records of SCI patients. Statistical testing used Mann-Whitney test for non-parametric variables, Fisher's exact test for contingency analysis and the Spearman correlation test to assess correlations. A p-value < 0.05 was considered significant. Statistical analyses were performed using GraphPad Prism v9.

RESULTS

173 patients (131 males, 42 females) were included. The majority of patients were paraplegic (n = 111 (64,2%)) and had complete lesions (n = 75 (43,4%)). A total of 100 patients had nocturia (57,5%). The prevalence of OSA (Apnea Hypopnea Index (AHI) ≥ 15/h) in the studied population was 61,9%. No correlation was found between nocturia and OSA. A significant difference was observed between patients with and without nocturia in terms of the presence of neurogenic detrusor overactivity (p = 0,049), volume at the first detrusor contraction (p = 0,004) and the bladder functional capacity (p < 0,001).

CONCLUSION

Nocturia and OSA are highly prevalent in patients with SCI, but no statistical association was found between these two disorders. A prospective study focusing on nocturnal polyuria will be needed to assess the impact of OSA on lower urinary tract symptoms in SCI patients.

Impact of activity-based recovery training and desmopressin on spinal cord injury-induced polyuria in Wistar rats

Activity-based recovery training (ABRT) reverses spinal cord injury (SCI) induced polyuria and alterations of biomarkers involved with fluid balance, including expression levels of kidney vasopressin 2 receptors. However, void volumes do not return to pre-injury baseline levels, indicating a combinatorial approach may be necessary.

In the current study, acute effects of a pharmacological intervention versus placebo were examined in male rats that had received 70 daily ABRT sessions. The treatment, desmopressin (DDAVP - synthetic analogue of arginine vasopressin), an antidiuretic therapy used for the management of bedwetting in children and central diabetes insipidus, has previously shown some promise in a few limited cohorts of SCI individuals having nocturnal polyuria.

A total of 70 sessions of ABRT over a 10-week timeframe again reduced the overproduction of urine, but not completely to pre-SCI baseline levels. DDAVP treatment maintained but did not further reduce the level of urine output in the ABRT group without continuous exercise, demonstrating either intervention/treatment alone is effective, despite no additive effect. Although intake did not change from pre-injury levels despite polyuria, DDAVP treatment also reduced drink volume.

Further studies are needed as the mechanisms underlying changes in fluid and solute balance are likely multi-factorial involving a complex interaction between the neural (both central and peripheral) control of systems mediating thirst, urinary output, and cardiovascular regulation.

Maladaptation of Renal Hemodynamics Contributes to Kidney Dysfunction Resulting from Thoracic Spinal Cord Injury in Mice

Renal dysfunction is a hallmark of spinal cord injury (SCI). Several SCI sequalae are implicated, however, the exact pathogenic mechanism of renal dysfunction is unclear. Herein, we found that T3 (T3Tx) or T10 (T10Tx) complete thoracic spinal cord transection induced hypotension, bradycardia, and hypothermia immediately after injury. T3Tx-induced hypotension but not bradycardia or hypothermia slowly recovered to levels in T10Tx SCI and uninjured mice ~16 h after injury as determined by continuous radiotelemetry monitoring. Both types of thoracic SCI led to a marked decrease in albuminuria and proteinuria in all phases of SCI, while the kidney injury marker, NGAL, rapidly increased in the acute phase, remaining elevated in the chronic phase of T3Tx SCI. Renal interstitial and vascular elastin fragmentation after SCI were worsened during chronic T3Tx SCI. In the chronic phase, renal vascular resistance response to a step increase in renal perfusion pressure or a bolus injection of Ang II or NE was almost completely abolished after T3Tx SCI. Bulk RNAseq analysis showed enrichment of genes involved in extracellular matrix (ECM) remodeling and chemokine signaling in the kidney from T3Tx SCI mice. Serum levels of interleukin 6 was elevated in the acute but not chronic phase of T3Tx and T10Tx SCI, while serum amyloid A1 level was elevated in both acute and chronic phases. We conclude that tissue fibrosis and hemodynamic impairment are involved in renal dysfunction resulting from thoracic SCI; these pathological alterations, exacerbated by high thoracic-level injury, is mediated at least partly by renal microvascular ECM remodeling.

Atrial Natriuretic Peptide and the Epithelial Sodium Channel Contribute to Spinal Cord Injury-Induced Polyuria in Mice

Polyuria is found in patients with spinal cord injury (SCI). However, the underlying cellular and molecular mechanism is unknown. Here, we show that mice had elevated urine for 7 days after T10 contusion. Using multi-photon confocal microscopy, we performed intra-vital imaging experiments to evaluate water reabsorption in kidney tubules by examining fluorescent intensity in the lumen of the distal tubule from live mice. The data show that SCI significantly reduced the concentrating function of kidney tubules. The reduced water reabsorption appears to be mediated by atrial natriuretic peptide (ANP) because SCI increased the expression levels of both ANP and natriuretic peptide receptor A (NPR-A) in the kidney cortex. Our patch-clamp single-channel recordings from split-open distal tubules show that SCI decreased the activity of the epithelial sodium channel (ENaC). Western blot combined with confocal microscopy data show that the levels of 70 kD γ-ENaC, which is an active isoform because of proteolytic cleavage, were significantly reduced in distal tubule principal cells. An NPR-A inhibitor (A71915) given intravenously eliminated the effects of SCI on ENaC and polyuria. These data together with previous studies suggest that SCI causes polyuria, probably by reducing ENaC activity through elevating ANP and NPR-A. Further investigation of the signal transduction pathways may provide useful information for discovering an efficient drug to treat SCI-induced polyuria.

Timeline of Changes in Biomarkers Associated with Spinal Cord Injury-Induced Polyuria

Deficits in upper and lower urinary tract function, which include detrusor overactivity, urinary incontinence, detrusor-sphincter dyssynergia, and polyuria, are among the leading issues that arise after spinal cord injury (SCI) affecting quality of life. Given that overproduction of urine (polyuria) has been shown to be associated with an imbalance in key regulators of body fluid homeostasis, the current study examined the timing of changes in levels of various relevant hormones, peptides, receptors, and channels post-contusion injury in adult male Wistar rats. The results show significant up- or downregulation at various time points, beginning at 7 days post-injury, in levels of urinary atrial natriuretic peptide, serum arginine vasopressin (AVP), kidney natriuretic peptide receptor-A, kidney vasopressin-2 receptor, kidney aquaporin-2 channels, and kidney epithelial sodium channels (β- and γ-, but not α-, subunits). The number of AVP-labeled neurons in the hypothalamus (supraoptic and -chiasmatic, but not paraventricular, nuclei) was also significantly altered at one or more time points. These data show significant fluctuations in key biomarkers involved in body fluid homeostasis during the post-SCI secondary injury phase, suggesting that therapeutic interventions (e.g., desmopressin, a synthetic analogue of AVP) should be considered early post-SCI.

Improvements in Bladder Function Following Activity-Based Recovery Training With Epidural Stimulation After Chronic Spinal Cord Injury

Spinal cord injury (SCI) results in profound neurologic impairment with widespread deficits in sensorimotor and autonomic systems. Voluntary and autonomic control of bladder function is disrupted resulting in possible detrusor overactivity, low compliance, and uncoordinated bladder and external urethral sphincter contractions impairing storage and/or voiding. Conservative treatments managing neurogenic bladder post-injury, such as oral pharmacotherapy and catheterization, are important components of urological surveillance and clinical care. However, as urinary complications continue to impact long-term morbidity in this population, additional therapeutic and rehabilitative approaches are needed that aim to improve function by targeting the recovery of underlying impairments. Several human and animal studies, including our previously published reports, have documented gains in bladder function due to activity-based recovery strategies, such as locomotor training. Furthermore, epidural stimulation of the spinal cord (scES) combined with intense activity-based recovery training has been shown to produce volitional lower extremity movement, standing, as well as improve the regulation of cardiovascular function. In our center, several participants anecdotally reported improvements in bladder function as a result of training with epidural stimulation configured for motor systems. Thus, in this study, the effects of activity-based recovery training in combination with scES were tested on bladder function, resulting in improvements in overall bladder storage parameters relative to a control cohort (no intervention). However, elevated blood pressure elicited during bladder distention, characteristic of autonomic dysreflexia, was not attenuated with training. We then examined, in a separate, large cross-sectional cohort, the interaction between detrusor pressure and blood pressure at maximum capacity, and found that the functional relationship between urinary bladder distention and blood pressure regulation is disrupted. Regardless of one's bladder emptying method (indwelling suprapubic catheter vs. intermittent catheterization), autonomic instability can play a critical role in the ability to improve bladder storage, with SCI enhancing the vesico-vascular reflex. These results support the role of intersystem stimulation, integrating scES for both bladder and cardiovascular function to further improve bladder storage.

Effect of bladder distension on arginine vasopressin secretion in rats

Objective

Results

Activity-Based Training Reverses Spinal Cord Injury-Induced Changes in Kidney Receptor Densities and Membrane Proteins

Complications in upper and lower urinary function arise after spinal cord injury (SCI), which creates a significant impact on quality of life for those affected. One upper urinary complication is SCI-induced polyuria, or the overproduction of urine, of which the underlying mechanisms have yet to be elucidated. Activity-based training (ABT) has been utilized in both animal and clinical settings as a rehabilitative therapy to improve many issues that arise after SCI, including more recently urogenital function. The goal of the current study was to identify potential mechanisms contributing to previously identified improvements in polyuria with ABT, using a male rat moderate-severe spinal contusion model. Although ABT had no significant effect on reversing injury-induced alterations of serum arginine vasopressin and urinary atrial natriuretic peptide levels, there was a dramatic effect upon the receptors of these fluid balance hormones (vasopressin receptor 2 and natriuretic peptide A receptor), as well as kidney aquaporin 2 and sodium channels. ABT changes in densities of key receptors and kidney membrane proteins involved in fluid balance after chronic SCI support the likelihood of multiple mechanisms through which exercise can positively influence urinary tract function after SCI. By understanding the mechanisms, amount, and timing regarding how ABT improves different aspects of urinary function, more targeted training strategies can be developed to optimize the functional gains within the SCI population.

Improvements in bladder, bowel and sexual outcomes following task-specific locomotor training in human spinal cord injury

OBJECTIVE

Locomotor training (LT) as a therapeutic intervention following spinal cord injury (SCI) is an effective rehabilitation strategy for improving motor outcomes, but its impact on non-locomotor functions is unknown. Given recent results of our labs' pre-clinical animal SCI LT studies and existing overlap of lumbosacral spinal circuitries controlling pelvic-visceral and locomotor functions, we addressed whether LT can improve bladder, bowel and sexual function in humans at chronic SCI time-points (> two years post-injury).

STUDY DESIGN

Prospective cohort study; pilot trial with small sample size.

METHODS

Eight SCI research participants who were undergoing 80 daily one-hour sessions of LT on a treadmill using body-weight support, or one-hour of LT and stand training on alternate days, as part of another research study conducted at the Kentucky Spinal Cord Injury Research Center, University of Louisville, were enrolled in this pilot trial. Urodynamic assessments were performed and International Data Set questionnaire forms completed for bladder, bowel and sexual functions at pre-and post-training time points. Four usual care (non-trained; regular at-home routine) research participants were also enrolled in this study and had the same assessments collected twice, at least 3 months apart.

RESULTS

Filling cystometry documented significant increases in bladder capacity, voiding efficiency and detrusor contraction time as well as significant decreases in voiding pressure post-training relative to baseline. Questionnaires revealed a decrease in the frequency of nocturia and urinary incontinence for several research participants as well as a significant decrease in time required for defecation and a significant increase in sexual desire post-training. No significant differences were found for usual care research participants.

CONCLUSIONS

These results suggest that an appropriate level of sensory information provided to the spinal cord, generated through task-specific stepping and/or loading, can positively benefit the neural circuitries controlling urogenital and bowel functions.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03036527.

Altered vasopressin and natriuretic peptide levels in a rat model of spinal cord injury: implications for the development of polyuria

Urinary dysfunction is a common complaint following spinal cord injury (SCI) and is a leading issue for individuals with SCI that impacts their quality of life. One urinary complication that has received little attention is SCI-induced polyuria, even though individuals with SCI will significantly restrict their fluid intake to decrease urine production, leading to sequelae of medical complications. Understanding the mechanisms instigating the development of polyuria will allow us to target interventions that may alleviate polyuria symptoms, leading to significant improvements in the quality of life and urinary health of individuals with SCI. In a rat SCI contusion model, an increase in the amount of urine excreted over a 24-h period ( P ≤ 0.001) was found at 2 wk postinjury. The urine excreted was more dilute with decreased urinary creatinine and specific gravity ( P ≤ 0.001). Several factors important in fluid balance regulation, vasopressin (AVP), natriuretic peptides, and corticosterone (CORT), also changed significantly postinjury. AVP levels decreased ( P = 0.042), whereas atrial natriuretic peptide (ANP) and CORT increased ( P = 0.005 and P = 0.031, respectively) at 2 wk postinjury. There was also a positive correlation between the increase in ANP and urine volume postinjury ( P = 0.033). The changes in AVP, ANP, and CORT are conducive to producing polyuria, and the timing of these changes coincides with the development of SCI-induced polyuria. This study identifies several therapeutic targets that could be used to ameliorate polyuria symptoms and improve quality of life in individuals with SCI.

Clinical Aspects of Human Circadian Rhythms

Circadian rhythmicity can be important in the pathophysiology, diagnosis, and treatment of clinical disease. Due to the difficulties in conducting the necessary experimental work, it remains unknown whether ~24-h changes in pathophysiology or symptoms of many diseases are causally linked to endogenous circadian rhythms or to other diurnal factors that change across the day, such as changes in posture, activity, sleep or wake state, or metabolic changes associated with feeding or fasting. Until the physiology is accurately known, appropriate treatment cannot be designed. This review includes an overview of clinical disorders that are caused or affected by circadian or diurnal rhythms. The clinical side effects of disruption of circadian rhythmicity, such as in shiftwork, including the public health implications of the disrupted alertness and performance, are also discussed.

Comparison of Sleep Problems in Individuals with Spinal Cord Injury and Multiple Sclerosis

STUDY OBJECTIVES

Sleep problems are common in spinal cord injury (SCI) and multiple sclerosis (MS). However, the degree to which sleep problems differ between these distinct clinical populations has not been evaluated. In this study, we examined self-reported sleep problems in individuals with SCI and those with MS, and compared these clinical groups on the Medical Outcomes Study Sleep Scale (MOS-SS).

METHODS

Participants were 1,677 individuals (SCI = 581; MS = 1,096) enrolled in longitudinal study of self-reported health outcomes in SCI and MS. Univariate and multivariate analysis of covariance examined group differences on global sleep problems and domain-specific subscales of the MOS-SS.

RESULTS

Individuals with SCI reported an average of 30 fewer min of sleep per night (Sleep Quantity subscale) and significantly greater difficulty initiating and maintaining sleep (Sleep Disturbance subscale) compared to individuals with MS. However, groups did not differ on global sleep problems (Sleep Problems Index 9).

CONCLUSIONS

Although global sleep problems are more common in SCI and MS than in the general population, these groups exhibit differing sleep problem profiles, and thus may require unique treatment approaches to address the specific domains of sleep affected. For individuals with SCI, an additional focus on increasing sleep quantity and reducing sleep disruptions may be warranted.

Effects of lateral funiculus sparing, spinal lesion level, and gender on recovery of bladder voiding reflexes and hematuria in rats

Deficits in bladder function are complications following spinal cord injury (SCI), severely affecting quality of life. Normal voiding function requires coordinated contraction of bladder and urethral sphincter muscles dependent upon intact lumbosacral reflex arcs and integration of descending and ascending spinal pathways. We previously reported, in electrophysiological recordings, that segmental reflex circuit neurons in anesthetized male rats were modulated by a bilateral spino-bulbo-spinal pathway in the mid-thoracic lateral funiculus. In the present study, behavioral measures of bladder voiding reflexes and hematuria (hemorrhagic cystitis) were obtained to assess the correlation of plasticity-dependent recovery to the degree of lateral funiculus sparing and mid-thoracic lesion level. Adult rats received mid-thoracic-level lesions at one of the following severities: complete spinal transection; bilateral dorsal column lesion; unilateral hemisection; bilateral dorsal hemisection; a bilateral lesion of the lateral funiculi and dorsal columns; or a severe contusion. Voiding function and hematuria were evaluated by determining whether the bladder was areflexic (requiring manual expression, i.e., "crede maneuver"), reflexive (voiding initiated by perineal stroking), or "automatic" (spontaneous voiding without caretaker assistance). Rats with one or both lateral funiculi spared (i.e., bilateral dorsal column lesion or unilateral hemisection) recovered significantly faster than animals with bilateral lateral funiculus lesions, severe contusion, or complete transection. Bladder reflex recovery time was significantly slower the closer a transection lesion was to T10, suggesting that proximity to the segmental sensory and sympathetic innervation of the upper urinary tract (kidney, ureter) should be avoided in the choice of lesion level for SCI studies of micturition pathways. In addition, hematuria duration was significantly longer in males, compared to females, despite similar bladder reflex onset times. We conclude that the sparing of the mid-thoracic lateral funiculus on one side is required for early recovery of bladder reflex voiding function and resolution of hematuria.

Bone biomarkers in patients with chronic traumatic spinal cord injury

BACKGROUND CONTEXT

Bone loss after spinal cord injury (SCI) occurs because of pathologic changes in osteoblastic and osteoclastic activities due to mechanical unloading. Some biochemical changes in bone metabolism after SCI are described before that were related to bone mineral loss.

PURPOSE

Our purpose was to determine bone markers' changes and related effective factors in patients with chronic traumatic SCI.

STUDY DESIGN

This investigation was designed as an observational cross-sectional study.

PATIENT SAMPLE

All patients with chronic SCI who were referred to Brain and Spinal Injury Research Center and did not meet our exclusion criteria entered the study.

OUTCOME MEASURES

Self-reporting measures including patient's demographic features and date of accident were obtained using a questionnaire and physiologic measures including spinal magnetic resonance imaging to determine the level of injury accompanied with physical examination along with dual-energy X-ray absorptiometry were performed. Blood samples were analyzed in the laboratory.

METHODS

Dual-energy X-ray was used to determine bone mineral density in femoral and spinal vertebrae bone sites. Serum level of C-telopeptide cross-linked Type 1 collagen (CTX), parathyroid hormone, calcitonin, osteocalcin, and bone alkaline phosphatase (BALP) were measured.

RESULTS

We detected a negative association between CTX level and bone mineral density in femoral and spinal bone sites that confirms that CTX is a bone resorption marker. C-telopeptide cross-linked Type 1 collagen and BALP levels did not show any significant correlation with postduration injury. Patients with spinal injury at lumbar level had the highest calcitonin level (p<.04). C-telopeptide cross-linked Type 1 collagen was positively related with osteocalcin and BALP (p<.0001, r=0.51), and osteocalcin was positively related with BALP (p<.0001, r=0.44). Osteocalcin was related negatively only to femoral intertrochanteric zone bone mineral density.

CONCLUSIONS

Some bone biomarkers undergo noticeable changes after SCI. C-telopeptide cross-linked Type 1 collagen was positively correlated with BALP and osteocalcin that shows the coincidental occurrence of osteoblastic and osteoclastic activities. Our data also support this fact that although bone reduction after 2 years is slower than acute phase after SCI, bone resorption rate is higher than bone formation. These bone markers also revealed different site of action as osteocalcin level only affected femoral intertrochanteric bone mineral density. Generally, it seems that the coincidental consideration of these factors that influence bone mineral density can lead to a better understanding of bone changes after SCI.

Persistent polyuria in a rat spinal contusion model

Polyuria contributes to bladder overdistention, which confounds both lower and upper urinary tract management in individuals having a spinal cord injury (SCI). Bladder overdistention post-SCI is one of the most common triggers for autonomic dysreflexia, a potentially life-threatening condition. Post-SCI polyuria is thought to result from loss of vascular tone in the lower extremities, leading to edema and subsequent excess fluid, resulting in polyuria. Mild SCIs that have near complete recovery would therefore be expected to have little to no polyuria, while severe injuries resulting in flaccid limbs and lower extremity edema would be expected to exhibit severe polyuria. Since interventions that may decrease lower extremity edema are recommended to lessen the severity of polyuria, step training (which promotes vascular circulation) was evaluated as a therapy to reduce post-SCI polyuria. In the present study, polyuria was evaluated in mild, moderate, and severe contusive SCI in adult male rats. The animals were housed in metabolic cages for 24-hour periods pre- and post-SCI (to 6 weeks). Urine, feces, food, water, and body weights were collected. Other assessments included residual expressed urine volumes, locomotor scoring, in-cage activity, and lesion histology. SCI produced an immediate increase in 24-hour urine collection, as early as 3 days post-SCI. Approximately 2.6-fold increases in urine collection occurred from weeks 1-6 post-SCI for all injury severities. Even with substantial gains in locomotor and bladder function following a mild SCI, polyuria remained severe. Step training (30 min/day, 6 days/week) did not alleviate polyuria in the moderate SCI contusion group. These results indicate that (1) mild injuries retaining weight-bearing locomotion that should have mild, if any, edema/loss of vascular tone still exhibit severe polyuria, and (2) step training was unable to reduce post-SCI polyuria. Taken together, these results indicate that the current mechanistic hypothesis of post-SCI polyuria may be incomplete.

Decreased nocturnal urinary antidiuretic hormone excretion in enuresis is increased by imipramine

OBJECTIVE

To assess the role of integrated nocturnal antidiuretic hormone (ADH) secretion in children with enuresis, and possible modifications induced by treatment with imipramine.

PATIENTS AND METHODS

The morning plasma ADH and nocturnal urinary ADH integrated concentrations were measured in 18 consecutive enuretic children (patients) and 21 age- and sex-matched controls admitted for minor treatment. Diurnal and nocturnal urine production, and plasma and urinary osmolality were also determined; lumbosacral radiography and uroflowmetry were undertaken in the patients. The assessments were repeated after 14 days of treatment with imipramine hydrochloride (orally, 20 mg/night).

RESULTS

Half the patients had occult spinal malformations but the uroflowmetry results were all within the normal range. The median (95% confidence interval, CI) urinary ADH integrated concentrations were markedly lower in patients, at 29.7 (22.1-37.3) vs 63.0 (35.1-90.8) pg/mL/h (P = 0.03) than in controls. Plasma ADH levels were significantly increased by imipramine (0.64 to 1.47 pg/mL, 95% CI, 0.40-0.89 vs -0.26-3.2; P < 0.001), as were nocturnal urinary ADH integrated concentrations, at 29.7 (22.1-37.3) vs 59.0 (37.3-80.6) pg/mL/h (P < 0.001), and morning plasma osmolality decreased, from 298.5 (294.5-302.5) to 294.9 (292.4-297.3) mosmol/kg (P = 0.003), as was the 24-h fluid intake, from 983 (721-1245) to 666 (435-897) mL (P = 0.004).

CONCLUSIONS

We conclude that enuretic children have a lower nocturnal ADH excretion; imipramine restores nocturnal ADH excretion, increases morning plasma ADH levels, and causes consistent changes in other biochemical variables.

Adrenal insufficiency masquerading as sepsis in a patient with tetraparesis: a case report

Several endocrine changes have been reported in patients with tetraplegia after spinal cord injury (SCI). These changes should be considered when prescribing medications that influence the endocrine pathways. Megestrol acetate has gained acceptance as a way to promote weight gain in cachectic patients without significant adverse effects. We present a case of a 51-year-old man with C5-C6 tetraparesis who was only 67% of his ideal body weight and was placed on megestrol acetate 5 months before admission for a urologic procedure. Postoperatively, the patient had severe hypotension and tachycardia that was interpreted as a septic or cardiac event. Further workup revealed subnormal levels of 8AM cortisol. An adrenocorticotrophic hormone stimulation test demonstrated results consistent with adrenal suppression. Hydrocortisone supplementation was started, and 6 months later cortisol levels were within normal limits. Cachexia, hypotension, and mild tachycardia are not uncommon in patients with SCI. When severe hypotension and tachycardia are seen in patients with tetraplegia, the diagnosis of adrenal insufficiency should be considered.

Low-dose desmopressin in the treatment of nocturnal urinary incontinence in the exstrophy-epispadias complex

OBJECTIVE

To report our experience of the use of desmopressin to improve nocturnal dryness in patients who have undergone a staged reconstruction of the exstrophy-epispadias complex (EEC), who although continent by day, have nocturnal incontinence because their nocturnal urinary output exceeds their bladder capacity.

PATIENTS AND METHODS

Seven children (aged 8-12 years) who had undergone a staged reconstruction for EEC (six with classical bladder exstrophy, one with incontinent epispadias) were treated with intranasal desmopressin for persistent nocturnal incontinence despite daytime dryness. Previous additional procedures for continence had been self-augmentation in one and periurethral collagen injection in three others. The criteria for inclusion in the study were: normal renal function, no upper tract deterioration, no urinary tract infections, spontaneous voiding during the day with dry intervals between micturitions, a postvoid residual volume of <10% of bladder capacity and night-time incontinence for 7 nights/week. Desmopressin was administered at bedtime at increasing dosages from 10 to 30 microg until effective. Body weight, arterial blood pressure, and serum electrolytes were measured, and all patients assessed using renal ultrasonography, a voiding diary and a nocturnal pad-test.

RESULTS

Desmopressin at doses of 10-30 microg was successful in keeping all the patients dry. The nocturnal urinary output was decreased so that it did not exceed bladder capacity. There was only one minor side-effect (nose bleeding).

CONCLUSIONS

In selected patients with EEC, desmopressin is effective in improving nocturnal dryness, with no significant side-effects.

Bone mineral density and indexes of bone metabolism in spinal cord injury

We evaluated the pattern of osteoporosis after spinal cord injury, determined the time-frame of the changes, and elucidated the relationship among parathyroid hormone levels, biochemical markers of bone formation, and the pattern of bone mass loss. We included 176 subjects with spinal cord injury and 62 subjects without spinal cord injury as controls in the study. Bone mineral density of the spine and the proximal femur was measured. The participants' age, level of injury, and length of time since injury were compared with the nonspinal cord-injured controls and with each other. Serum levels of calcium, calcitonin, biochemical markers of bone formation, and parathyroid hormone were determined. Our results revealed that bone mineral density of the proximal femur declined and reached fracture threshold at one to five years after injury. The decline was detected at 12 months after injury in all age groups. Spinal bone mineral density neither declined significantly nor reached fracture threshold. Parathyroid hormone levels declined before the end of the first year postinjury and increased at one to nine years postinjury in the 20- to 39-year age group. The increase correlated with the initial decline of bone mineral density of the proximal femur. Our studies in spinal cord-injured subjects revealed a pattern of osteoporosis similar to age and parathyroid dysfunction-related osteoporosis. No other correlation was detected between indexes of bone metabolism and bone mineral density measurements.