Symptoms and incidence of neuroborreliosis (NB) were studied in ambulatory patients visiting the ENT clinic in Helsinki. Especially we tried to search for possible markers indicating the connection between vestibular neuronitis and NB. A total of 350 patients were screened with the enzyme-linked immunosorbent assay (ELISA) technique for possible antibodies against Borrelia burgdorferi (BB). Twelve patients had positive serological reactions for BB with sera titer levels ranging from 640-14700 (normal < 500). In 2 additional cases, NB was clinically confirmed. In 7 cases a history of tick bite and in 4 cases erythema chronicum migrans was confirmed. In 9 cases, vertigo was the predominant symptom, and in 3 cases the symptoms were linked to facial nerve paresis. Six patients suffered from hearing loss. In 7 cases, the diagnosis was initially settled as vestibular neuronitis. NB seems to be present in about 4% of cases with apparent otologic diseases in Finland. In the majority of the cases, the
disease resembles vestibular neuronitis in the acute stage. Since NB is tractable, all patients visiting the ENT clinic, especially those with vertigo, should be screened.