Congenital structural disorders Flashcards
What is the pathophysiology behind Hirschsprung’s disease?
Absent parasympathetic ganglion cells in myenteric and submucosal plexus of rectum +/- colon.
Ganglion cells are of neural crest origin and they migrate caudally with vagal nerve fibres, arriving at the proximal colon by 8 weeks and rectum by 12 weeks of age.
Arrest in this migration –> aganglionic segment
90% short segmenting in rectosigmoid only
5% entire colon –> agangliosis coli –> need ileostomy
Is there a gender bias in Hirschsprungs and what conditions is it associated with?
Male»_space;> female (4: 1)
A/w:
- Down syndrome (5-15% have HD)
- Ondine’s curse (congenital central hypoventilation syndrome)
- Congenital deafness
- Malrotation / gastric diverticulum / intestinal atresia
- Waardenburg syndrome (deafness / pigmentation / defect in structures arising from neural crest)
What is the gene related to Hirschsprung’s?
RET proto-oncogene
How is diencephalic syndrome related to failure to thrive?
Benign astrocytomas affecting the hypothalamus and thalamus bilaterally can present, typically in the second or third year of life, with failure to thrive in the face of a cheerful, alert demeanor, preserved appetite, and normal or nearly normal development . A distinctive feature of this syndrome, sometimes referred to as the diencephalic syndrome of Russell, is a striking absence of subcutaneous adipose tissue.
What should you think about in a child with painless, PR bleeding?
Merkel’s diverticulum
- ix of choice is the meckel radionuclide scan, which is performed after intravenous infusion of technetium-99m pertechnetate.
The mucus-secreting cells of the ectopic gastric mucosa take up pertechnetate, permitting visualization of the Meckel diverticulum. The uptake can be enhanced with various agents, including cimetidine, glucagon, and gastrin. The sensitivity of the enhanced scan is approximately 85%, with a specificity of approximately 95%.
