P88-T Clinical and neurophysiologic characterization of the diabetic truncal mononeuropathy

Background Thoraco-abdominal or truncal nerves can be selectively affected in diabetic patients. The clinical picture shows predominantly sensory symptoms like pain, paresthesia, and occasional motor involvement. This mononeuropathy can be misdiagnosed with different thoracic-abdominal conditions (herpes zoster, angor pectoris, acute abdomen, intraabdominal tumours,…). It usually occurs between the 5th and 6th decades, with an insidious or subacute onset. We present a series of 4 cases in which electrodiagnostic testing was decisive for the diagnosis. Material and methods All the patients presented a long history of type 2 diabetes, and complained of poorly defined abdominal pain, without finding a cause that justified the symptoms in a prior extensive clinical investigation (including analytics and imaging studies). The neurophysiologic study consisted on motor and sensory conduction studies and quantitative needle electromyography of the rectus abdominis and external abdominal oblique muscles. Results In every case electromyography showed a subacute-chronic neurogenic pattern, characterized by complex and long-duration motor unit potentials, with an increased percentage of polyphasic potentials. In three cases we found spontaneous activity (fibrillation potentials or positive sharp waves). The study was compatible with the diagnosis of truncal neuropathy/radiculopathy. In half of the patients it was associated with a mixed sensory-motor polyneuropathy. Conclusions Truncal mononeuropathy in diabetic patients is most likely underdiagnosed, probably because the unspecific clinical presentation, including very variable sensory symptoms that mimic other conditions. Once the diagnosis of presumption is stablished, it is easily confirmed neurophysiologically, with electromyography being the technique that provides the most information for the diagnosis.