Hypothesis / aims of study
Spinal dysraphism (SD) are congenital malformations resulting from a defect in the closure of the components of the spine and spinal cord. There are two types of SDs: open SDs, or "spina bifida aperta", in which there is no skin coverage (e.g., myelomeningocele); closed SDs, or "spina bifida occulta", in which the malformation is covered (e.g., filum terminale lipoma, dermal sinus, etc.). Lower urinary tract dysfunction is common in people with DS, and lower urinary tract symptoms have a significant impact on quality of life. Nocturia, defined as waking up to pass urine during desired sleep hours, is one of the most common and troublesome urinary symptoms in neurological conditions [1]. While the epidemiology of urinary incontinence is well documented in patients with DS, no study describes the prevalence of nocturia in this population.
The objective of this study is to evaluate, in a cohort of patients with DS, the prevalence of nocturia and its mechanism.
Study design, materials and methods
This is a single-center cross-sectional analysis of consecutive patients with spinal dysraphism who underwent urodynamic evaluation in a rehabilitation medicine department of a university hospital.
Participants were community-dwelling men and women with SD who presented for urodynamic evaluation and who filled a bladder diary. Inclusion criteria were age ≥18 years and diagnosis of DS. Exclusion criteria were factors associated with atypical nocturia: receiving end-of-life care or other end-stage malignancies, end-stage renal disease, bladder cancer, previous pelvic radiation therapy.
Participants were classified as having or not having nocturia, with or without nocturnal polyuria. Nocturia was defined as at least one nightly awakening to void. This variable was collected at the 1st assessment in the department. Nocturnal polyuria was defined as a proportionally increased production of urine during the night relative to the 24-hour urine volume using the nocturnal polyuria index (NPi), nocturnal polyuria rate (NUPr), and nocturia index (Ni). NPi is the ratio of nocturnal to 24-hour urine volume (%). NUPr is the ratio of nocturnal urine volume to the duration of the sleep period (mLs/h). Ni is the ratio of nocturnal urine volume to maximum bladder capacity. Nocturnal polyuria is defined as NPi=33% in adults over 65 years, >20% in young adults, and between 20 and 33% in middle-aged adults; NUPr>90ml/h; Ni>1.5 This variable was collected by bladder diary analysis. Descriptive statistics were performed to determine the prevalence of nocturia in this population and its mechanism.
Results
31 patients were included, totaling 55 visits (median age 29 [21 ;39], 68% female). The majority of patients (n=17) had an open DS and had walking autonomy (n=22). The main urinary complaint was the presence of mixed urinary incontinence (n=10). The most frequent urodynamic diagnosis was the presence of detrusor overactivity (n=13), associated with intrinsic sphincter insufficiency in half of the cases. Only 5 patients had nocturia, with a median episode of 0.5 (0;1). Of the 27 bladder diaries available, 5 found nocturnal polyuria defined by NPi, 1 with Ni and none with NUPr. Of the 5 patients with nocturnal polyuria, only 3 complained of nocturia. The two patients complaining of nocturia and not having nocturnal polyuria had intrinsic sphincter insufficiency or detrusor overactivity.
Interpretation of results
Although the sample size is limited, this is the first study to look specifically at this urinary symptom in this rare disease. The prevalence of nocturia seems small compared to other urinary symptoms, but when compared to the general population in the same age group, it seems higher (14% in 18-29 year olds and 17.5% in 30-39 year olds [2]). Several factors could explain this, including the higher prevalence of obesity in this population, or Chiari malformations causing sleep apnea.