From an otological standpoint, Lyme disease can manifest itself as Ménière's 
disease both clinically and electrophysiologically. The aim of this study was to 
describe the findings of routine clinical, auditory and vestibular tests in 
patients with Ménière's and Lyme disease and to use electrocochleography (ECoG) 
to assess the presence of endolymphatic hydrops (EH) in both diseases. 
Transtympanic ECoG was performed in 91 patients with Ménière's disease and in 11 
patients with confirmed Lyme disease. In both diseases the majority of patients 
had more than one complaint. There was one case with isolated hearing loss in 
the Lyme disease group. Typical clinical manifestations of Ménière's disease 
(vertigo, sensorineural hearing loss and tinnitus) were found in 6/11 patients 
(54.5%) in the Lyme disease group. The ECoG results indicated that there were 
65/91 patients (71.4%) with Ménière's disease and 5 patients (45.5%) with Lyme 
disease who presented with EH. No statistically significant difference was found 
between the incidence of different symptoms of Ménière's and Lyme disease. On 
the basis of these results, patients with Lyme disease should undergo careful 
examination and investigation, especially in endemic regions. The presence of EH 
does not exclude the presence of infection with borreliosis as a cause of 
Ménière's disease-like symptoms.