What is the 'leading edge' of a transition zone in Hirschsprung's disease, and why is it important?

Time to dip into the old stash for an interesting paper. This one was out of St Louis, MO and looked at the properties of the transition zone of ganglion cells in HD by taking sequential cross sections of surgical specimens and quantifying the ganglion cells in the submucosal and myenteric plexus.

The authors noted that the transition zone was not uniform, but instead had a leading edge (analogous to dripping paint). This leading edge of the transition zone was measured to be up to 2.1 cm (average 1.1 cm) and 2.4 cm (average 1.4 cm) long in the submucosal and myenteric plexuses, respectively. Additionally, the number of ganglion cells at the tip of the leading edge was normal.

The significance of this finding is that a frozen section biopsy performed at the transition zone may result in a pull-through that includes abnormal bowel and potentially poor functional results. The authors thus recommended that a pull-through be performed using bowel that is at least 2 cm proximal to the area of 'normal' ganglionated bowel identified intraoperatively by frozen section

Reference:
White et al. Circumferential distribution of ganglion cells in the transition zone of children with Hirschsprung's disease. Pediatric and Developemental Pathology (2000) 3, 216

What to do with a child in the ED after a household electrocution?

So a kid gets bounced around hospitals before being sent to our ED for admission. Shortly after, we send the kiddo home with some local wound care to a blister.

Low voltage electrocution (<1000 volts) is a common household injury that is usually a result of contact with electric cords and wall outlets. One of the main concerns with electrocution is related to cardiac consequences, specifically ventricular fibrillation and direct myocardial injury.

Chen et al reviewed the literature pertaining to the management and outcome of children exposed to a low voltage current (usually household appliances with a maximal voltage of 240V). They summarized the results of 7 retrospective studies that evaluated the relationship between the type of voltage, patients symptomatology at the scene (cardiac arrest, ventricular fibrillation), EKG findings (when an EKG was performed), and patient outcome.

The upshot of the review article was that healthy children who are exposed to household currents, when asymptomatic at the field and in the ED, had a very low risk of developing cardiac arrhythmias. When the children did have 'benign' arrhythmias (mainly sinus tacchycardia, vernticular premature complexes, and premature junctional complexes), those resolved spontaneously. Children who did not have abnormal EKG findings never developed any late arrhythmias.

The authors concluded that it is safe to discharge asymptomatic children exposed to household currents without and EKG or telemetry.

Reference:
Chen EH, Amit S. Do children require ECG evaluation and inpatient telemetry after household electrical exposure. Annals of Emergency Medicine 2007;49:64-67