There are cases when patients are clearly ill and the potential explanations are quite unsatisfactory. Most patients with intractable nausea and vomiting have a specific etiology for this. A disorder, rarely seen by gastroenterologists, has been identified that provides a detailed reason for a few patients with an “idiopathic vomiting” diagnosis (Clin Gastroenterol Hepatol 2013; 11: 240-5).
The authors examined a database of patients who presented with vomiting for autoantibodies to aquaporin-4 (AQP4).
Background: These autoantibodies are sensitive and specific for neuromyelitis optica (NMO). In fact, finding these autoantibodies in serum or spinal fluid allows distinction of NMO spectrum disorders (NMOSDs) from multiple sclerosis.
In patients with NMOSDs, there are typical brain MRI findings in AQP4-enriched areas, including the fourth ventricle floor which contains the chemosenisitve nausea and vomiting center (area postrema). AQP4 is the principal water channel in the central nervous system.
Design: The authors reviewed their database of 70 NMOSD patients to determine how many presented with vomiting. In addition, they tested serum samples from patients who presented with idiopathic nausea and vomiting for AQP4-IgG from the gastroparesis research registry. This included 318 patients with gastroparesis and 117 patients without gastroparesis.
Results: Ten patients (14% of NMOSD database) presented with intractable vomiting. The youngest patient in this group was 26 years old. All of these patients had a noncyclic pattern of vomiting. Four had associated hiccups. No control patients from the gastroparesis database was identified as having AQP4-IgG.
Why this is important: Early diagnosis allows initiation of immunosuppressant therapy which may modify the disease course. AQP4-IgG positivity predicts a high likelihood of relapsing attacks of optic neuritis and transverse myelitis.