RESUMO
Median arcuate ligament syndrome (MALS) is uncommon and often difficult to diagnose due to the vague presenting symptoms of abdominal pain, weight loss, and early satiety. Here, we report the case of a 63-year-old man who was successfully treated with laparoscopic median arcuate ligament release. Computed tomography (CT) of the abdomen and pelvis performed preoperatively demonstrated compression of the celiac artery with post-stenotic dilatation consistent with MALS. Subsequently, laparoscopic median arcuate ligament release was performed without any complications. Postoperatively, the patient reported resolution of abdominal pain with increased appetite and weight gain. Nonspecific abdominal pain and weight loss may raise concern for malignancy, but MALS should also be considered in the differential diagnoses. Diagnosis can be confirmed with CT and/or angiography. Median arcuate ligament release results in partial if not complete resolution of symptoms due to decompression of the celiac artery as well as division of the overlying celiac plexus.
RESUMO
Modulatory neurons project widely throughout the brain, dynamically altering network processing based on an animal's physiological state. The connectivity of individual modulatory neurons can be complex, as they often receive input from a variety of sources and are diverse in their physiology, structure, and gene expression profiles. To establish basic principles about the connectivity of individual modulatory neurons, we examined a pair of identified neurons, the "contralaterally projecting, serotonin-immunoreactive deutocerebral neurons" (CSDns), within the olfactory system of Drosophila Specifically, we determined the neuronal classes providing synaptic input to the CSDns within the antennal lobe (AL), an olfactory network targeted by the CSDns, and the degree to which CSDn active zones are uniformly distributed across the AL. Using anatomical techniques, we found that the CSDns received glomerulus-specific input from olfactory receptor neurons (ORNs) and projection neurons (PNs), and networkwide input from local interneurons (LNs). Furthermore, we quantified the number of CSDn active zones in each glomerulus and found that CSDn output is not uniform, but rather heterogeneous, across glomeruli and stereotyped from animal to animal. Finally, we demonstrate that the CSDns synapse broadly onto LNs and PNs throughout the AL but do not synapse upon ORNs. Our results demonstrate that modulatory neurons do not necessarily provide purely top-down input but rather receive neuron class-specific input from the networks that they target, and that even a two cell modulatory network has highly heterogeneous, yet stereotyped, pattern of connectivity.SIGNIFICANCE STATEMENT Modulatory neurons often project broadly throughout the brain to alter processing based on physiological state. However, the connectivity of individual modulatory neurons to their target networks is not well understood, as modulatory neuron populations are heterogeneous in their physiology, morphology, and gene expression. In this study, we use a pair of identified serotonergic neurons within the Drosophila olfactory system as a model to establish a framework for modulatory neuron connectivity. We demonstrate that individual modulatory neurons can integrate neuron class-specific input from their target network, which is often nonreciprocal. Additionally, modulatory neuron output can be stereotyped, yet nonuniform, across network regions. Our results provide new insight into the synaptic relationships that underlie network function of modulatory neurons.
