Perinatal development of lumbar motoneurons and their inputs in the rat.

The rat is quite immature at birth and a rapid maturation of motor behavior takes place during the first 2 postnatal weeks. Lumbar motoneurons undergo a rapid development during this period. The last week before birth represents the initial stages of motoneuron differentiation, including regulation of the number of cells and the arrival of segmental and first supraspinal afferents. At birth, motoneurons are electrically coupled and receive both appropriate and inappropriate connections from the periphery; the control from supraspinal structures is weak and exerted mainly through polysynaptic connections. During the 1st postnatal week, inappropriate sensori-motor contacts and electrical coupling disappear, the supraspinal control increases gradually and myelin formation is responsible for an increased conduction velocity in both descending and motor axons. Both N-methyl-D-aspartate (NMDA) and non-NMDA receptors are transiently overexpressed in the neonatal spinal cord. The contribution of non-NMDA receptors to excitatory amino acid transmission increases with age. Activation of gamma-aminobutyric acid(A) and glycine receptors leads to membrane depolarization in embryonic motoneurons but to hyperpolarization in older motoneurons. The firing properties of motoneurons change with development: they are capable of more repetitive firing at the end of the 1st postnatal week than before birth. However, maturation does not proceed simultaneously in the motor pools innervating antagonistic muscles; for instance, the development of repetitive firing of ankle extensor motoneurons lags behind that of flexor motoneurons. The spontaneous embryonic and neonatal network-driven activity, detected at the levels of motoneurons and primary afferent terminals, may play a role in neuronal maturation and in the formation and refinement of sensorimotor connections.

Use of polydimethylsiloxane for endoscopic treatment of neurogenic urinary incontinence in children.

PURPOSE: We report on the injection of polydimethylsiloxane for endoscopic treatment of urinary incontinence in children with neurogenic bladder and determine the optimal criteria for patient selection. MATERIALS AND METHODS: We have treated 17 boys and 16 girls since 1995. The etiology of incontinence was spina bifida in 24 cases. Previous surgery was performed in 18 patients, including bladder neck reconstruction in 15 and bladder augmentation in 9. Mean patient age at injection was 13 years (range 7 to 17). We administered 1, 2 and 3 injections in 21, 11 and 1 patients, respectively. Mean volume at each injection was 3.2 cc. Mean interval between injections was 6 months (range 3 to 15). In all cases injection was done transurethrally. RESULTS: Followup ranged from 6 to 41 months (median 16). A total of 11 patients (33.3%) are dry (continence for greater than 4 hours and no urinary pad use during the day) and 8 (24.2%) are improved (continence for 2 to 3 hours and minimal pad use). Results are poor in 14 cases. Overall previous bladder neck surgery or preoperative detrusor hyperactivity did not influence results. Good results were mainly associated with female gender (47.4% of girls versus 10.5% of boys achieved cure). CONCLUSIONS: Injection of polydimethylsiloxane at the bladder neck resulted in continence in 33% of neurogenic bladder cases. Better results occurred in girls and injection did not compromise other surgical procedures. Polydimethylsiloxane seems more suitable than bovine collagen due to potential problems with biological product use.

[Abdominal cystic lymphangiomas in children. Clinical, diagnostic and therapeutic aspects: apropos of 21 cases]. / Les lymphangiomes kystiques abdominaux de l'enfant. Aspects cliniques, diagnostiques et thérapeutiques: à propos de 21 observations.

Twenty-one abdominal cystic lymphangiomas were observed in paediatric patients during a 15-year period, in 11 boys and 10 girls. Diagnosis was prenatal in 2 cases; the mean age of the other 19 children was 4.7 years (range: 3 months-8 years). Tumours were intraperitoneal in 16 cases and retroperitoneal in 5 cases. Symptoms were variable: abdominal pain in 15 cases, palpable tumour in 6 cases (excluding the two cases of prenatal diagnosis). Complications included obstruction in 7 cases (including 3 by volvulus), infection in 6 cases, and intracystic haemorrhage in 3 cases. Abdominal ultrasonography correctly established the diagnosis in all children. Surgical treatment included 20 complete resections and one incomplete resection, including 6 with bowel resections. With a follow-up ranging from 6 months to 10 years, one recurrence occurred and was successfully reoperated. Intraabdominal cystic lymphangioma in childhood is a rare tumour with a variable presentation. An accurate diagnosis can be established by abdominal ultrasound. Complete resection should be performed whenever possible.

[Persistent urination disorders after treatment of posterior urethral valve: incidence and semiology]. / Les troubles mictionnels persistant après traitement d'une valve de l'urètre postérieur: incidence et sémiologie.

Micturition disorders were studied retrospectively in a series of 165 children over a period of 15 years. Among patients without lesions of the upper tract at the time of diagnosis (group A, n = 131), 18 (14%) had persistent nocturnal and diurnal enuresis: one urethral stenosis and six vesicoureteric reflux required surgery; three experienced persistent pollakiuria and enuresis. Among patients with upper urinary tract damage at the time of diagnosis (group B, n = 34), seven presented with recurrent urinary tract infection, five with nocturnal and diurnal enuresis and three with urolithiasis. In the long term, only 52% of them had normal renal function and two were successfully transplanted. Micturition disorders following treatment of posterior urethral valves are frequent and usually related to the so-called valve bladder syndrome. Iatrogenic complications and mortality rate have dramatically decreased during the recent years but long-term renal function impairment remains the most critical problem.