[Central or vestibular vertigo? Diagnostic look through Frenzel glasses].

Vertigo is not a uniform symptom. The basis for a differentiated diagnosis is the history, which should record the frequency and duration of attacks. Further diagnostic investigations serve to differentiate between non-vestibular and vestibular (peripheral) forms of vertigo. Of essential importance is the determination of nystagmus with the aid of Frenzel lenses, with distinction being made between voluntary nystagmus and provoked nystagmus. These orientating examinations, which can be carried out by the family doctor, set the points for the further course. On account of the need for special equipment, such studies as the caloric tests, the swivel chair test, optokinetic tests or the tilting stage test, remain the domain of the specialist. They enable a definitive differentiation of an ENT illness from a neurological disorder.