Die Ableitung olfaktorisch evozierter Potenziale in Patienten mit limbischer Enzephalitis

Objective Limbic encephalitis (LE) refers to an inflammatory process localized to structures of the limbic system that causes different neurologic and psychiatric disorders. To our knowledge, this is the first study investigating the olfactory function with olfactory evoked potentials (OEP) of patients with paraneoplastic or autoimmune encephalitis. Methods 19 LE patients (9 female, 10 male, mean age 47 years) and 19 age- and sex-matched healthy controls (HC) were tested. The Threshold Discrimination Identification test (TDI) was used to test orthonasal olfactory function. OEPs were recorded for objective olfactometry. Results 10 LE patients (53%) were hyposmic, 2 patients anosmic (11%) and 7 patients normosmic (36%). Their mean TDI value±standard deviation was 27.3±6.7. All LE patients with olfactory dysfunction also showed pathological OEPs. All 19 HCs were normosmic with a mean TDI value of 34.7±2.2. There was a significant reduction of the LE patients' TDI score compared to the HC (p<0.0001). Conclusions Olfactory dysfunction seems to be a frequent symptom in LE patients. This might be due to structural changes of the limbic system. OEPs were a suitable method to detect olfactory dysfunction in these patients.