Clinical scenario: lumbosacral swelling | UTI | proteinuria | hydronephrosis
A 12-year-old girl is evaluated for progressive abdominal distension over the past month. She has a history of surgery for a lumbosacral swelling during infancy and has required intermittent catheterization since early childhood because of urinary incontinence. Examination reveals gross ascites, bilateral pedal edema, and a healed lumbosacral surgical scar. Blood pressure is 145/95 mmHg. Urinalysis shows 4+ protein with numerous leukocytes. Serum albumin is 1.8 g/dL and serum creatinine is elevated. Renal ultrasound demonstrates bilateral hydronephrosis with cortical scarring.
Which of the following congenital anomalies is most likely associated with her underlying neurological disorder?
A. Arnold–Chiari II malformation
B. Dandy–Walker malformation
C. Holoprosencephaly
D. Joubert syndrome
E. Vein of Galen malformation
Correct answer & Explanation:
Correct answer: A. Arnold–Chiari II malformation
Explanation
This child most likely had myelomeningocele, suggested by the repaired lumbosacral lesion and lifelong neurogenic bladder requiring clean intermittent catheterization. Chronic neurogenic bladder predisposes to recurrent urinary tract infections, vesicoureteric reflux, reflux nephropathy, chronic kidney disease, and heavy proteinuria, resulting in hypoalbuminemia and ascites.
Arnold–Chiari II malformation is present in the vast majority of patients with myelomeningocele and is characterized by downward herniation of the cerebellar vermis, cerebellar tonsils, medulla, and fourth ventricle through the foramen magnum. Hydrocephalus is also common due to aqueductal obstruction.
Why the other options are incorrect
- B. Dandy–Walker malformation – Characterized by cystic dilatation of the fourth ventricle, hypoplasia of the cerebellar vermis, and enlarged posterior fossa. It is not associated with myelomeningocele or neurogenic bladder.
- C. Holoprosencephaly – Results from failed forebrain division and presents with severe craniofacial abnormalities rather than spinal dysraphism.
- D. Joubert syndrome – Presents with hypotonia, developmental delay, abnormal breathing, and the “molar tooth sign” on MRI; it is not linked to myelomeningocele.
- E. Vein of Galen malformation – Causes high-output cardiac failure or hydrocephalus in infancy and is unrelated to neural tube defects.
High-yield pearl
Neurogenic bladder is the leading cause of long-term renal morbidity in children with myelomeningocele. When a patient with repaired myelomeningocele presents with edema or ascites, always consider chronic kidney disease with heavy proteinuria secondary to reflux nephropathy. The congenital CNS anomaly classically associated with myelomeningocele is Arnold–Chiari II malformation.
