Oral

Background/Aims:
Paediatric intestinal pseudo-obstruction (PIPO) is a severe gastrointestinal motility disorder, characterized by functional obstruction of the small intestine in the absence of luminal occlusion. Organ bath contractility allows direct evaluation of intestinal neuromuscular function. We aimed to evaluate intestinal neuromuscular contractile pattes in PIPO patients.

Methods:
Small intestinal tissue was obtained from PIPO patients who required surgery, and those with presumably normal small intestinal neuromuscular function undergoing bowel surgery for other clinical indications. Longitudinal muscle strips were attached to an optical force transducer and maintained physiologically. Spontaneous contractile activity was recorded, followed by electrical field stimulation +/- atropine, L-NAME or carbachol. Immunohistochemistry was used to examine neuromuscular structure. All values are normalized to tissue weight and compared between groups by Student's t-test (mean±SEM).  

Results:
Eight PIPO patients (aged 5.28±1.48 years) and 10 controls (8.98±1.64 years) were included. The frequency of contractions at baseline was significantly lower in PIPO than controls (5.53±1.27 vs. 8.27±0.53 cycles/min; P=0.047). The ratio of amplitude in response to carbachol was not different between groups (P=0.829).
In PIPO samples, the area under the curve (AUC) upon EFS was 54.96±16.88 g tension.s.g wet weight-1. In the presence of atropine, this reduced to 13.09±3.98. Further addition of L-NAME resulted in a mean AUC of 7.76±2.95. In controls, the AUC upon EFS was 66.69±12.97, changed to 17.83±4.98 and 19.61±5.26 in the presence of atropine and L-NAME, respectively. The ratio of responses to L-NAME, as compared to atropine, were significantly different between PIPO and controls (0.643±0.136 vs. 1.139±0.074; P=0.004).
Immunostaining revealed two muscular layers in all samples (except one myopathic PIPO sample) and no disceible visual differences in the presence of excitatory or inhibitory neurons between the two groups.

Conclusions:
This preliminary study shows promising utility of tissue contractility tests for the diagnosis and characterization of intestinal motility disorders.