CASE REPORT: A case description of suppression of post-caloric nystagmus is presented that was not related to vestibular disorders. Methodology: The application of caloric testing under different environmental conditions was performed. In the first vestibular examination, the patient kept their eyes closed during the caloric test. In the second step, the same patient kept their eyes open in the dark during the caloric test using Video-Frenzel (Digital Frenzel, Contronic, Pelotas, Brazil). Results: Bilateral suppression of post-caloric nystagmus in the first test and a normal result was noted, with nystagmus recorded in the second exam. CONCLUSION: Patients undergoing a caloric test may show an absence of post-caloric nystagmus associated with labyrinth disease or the inherent conditions of the test itself, without any relation to vestibular involvement. In the absence of bilateral response after caloric stimulation, it has been recommended that the test be repeated with the patient's eyes open in the dark to ensure there is a real commitment of vestibular function or to determine if the response was suppressed by Bell Phenomenon, which is defined as deviation and adduction of the eyeball that can occur in some normal individuals during eye closure, inhibiting the onset of post-caloric nystagmus, and having no relation to labyrinth disease. Ignoring this measure may lead to diagnostic errors.
