Evaluation of dysfunction and malformations of the urinary tract in patients with meningomyelocele, by renal dynamic scintigraphy and direct radionuclide cystography. An Indian perspective.

Meningomyelocele (MMC) is the most common form of neural crest closure defect and may be associated with dysfunction and malformations of multiple organs including urinary tract. It affects as many as 2-4 in 1000 live births, however there are no epidemiological studies available from India. Anatomical and neurogenic abnormalities of the urinary tract are known to occur in these patients. Scanty literature is available regarding the utility of radionuclide procedures in the evaluation of urinary tract in patients of MMC. The aim of this study was to evaluate urinary tract dysfunction and malformations in patients operated of MMC by diuretic renal dynamic scintigraphy (RDS) and direct radionuclide cystography (DRCG). In this retrospective analysis, 140 operated patients for MMC, mean age: 4.46, range: 1-18 years; 83 male and 57 female, referred to our department for evaluation of the upper renal tract, were studied. Neurogenic bladder (NB) was associated in 69 patients. The diagnosis of NB was based on clinical features like incontinence, expressibility of urine bladder and on urodynamic studies. RDS was performed after the intravenous administration of 10.36 MBq/kg of technetium-99m diethylene triamine penta-acetate or 99mTc-L, L-ethylenedicysteine. All patients with hydronephrosis (HDN) or hydroureteronephrosis (HDUN) on RDS underwent DRCG using 11.1-18.5 MBq of 99mTc-sulphur colloid. Our results showed that: out of the 140 patients, 78 (56%) including 33 with NB, had normal renal scintigraphy. Six patients (4%) had congenital renal anomalies. Twenty patients (14%) revealed non-obstructive HDN and had no vesico-ureteric reflux (VUR). Thirty-six patients (26%) with bilateral HDUN also had NB of which 19 (53%) had VUR. Fourteen (74%) of these patients with VUR had impaired renal function. In discussion, patients with MMC may present with disordered innervation of the detrussor muscle and external sphincter, which adversely affects the bladder function and potentially threatens the upper urinary tract. Patients of MMC with or without NB can be evaluated with RDS for congenital anomalies and initial assessment of renal function. Patients with NB and particularly those with HDUN can be evaluated with DRCG for the presence of VUR to prevent renal scarring and subsequent impairment of renal function. Long-term surveillance of the urinary tract is important in the management of these patients and this can be accomplished with RDS and DRCG. In conclusion, in our patients with MMC, the tests of RDS, and DRCG could differentiate those with normal or our abnormal renal anatomy and function while the major group of patients had bilateral HDUN and NB, and/or VUR or impaired renal function.