A CBC, thyroid function tests, and glucose and vitamin B 12 levels should be obtained for all elderly persons presenting with chronic dizziness. Indications for ECG, Holter monitoring, carotid sinus massage, and tilt table testing are discussed in Ch. 18. However, abnormal findings are common among elderly patients with or without dizziness, and abnormal results may or may not correspond to the complaint of dizziness in this age group. Cerebral CT or MRI should be performed only if the history and physical examination suggest a cerebral lesion. Vestibular testing, including caloric testing, electronystagmography, rotational testing, and computerized posturography, can be considered in patients with history or physical examination findings suggestive of vestibular disease.
Caloric testing assesses the symmetry of vestibular function.
The ear that shows a shorter duration or lower frequency of nystagmus is presumed to be the diseased ear. Rotational testing uses a series of well-controlled rotational stimuli to provoke nystagmus. Electronystagmography, in which eye movements are recorded on an ECG-like tracing from electrodes placed around the eyes, is used to observe vestibular nystagmus during provocative testing. In computerized posturography, the patient stands on a platform that is imbedded with four sensors to monitor sway. Testing with the eyes closed or with a moving screen while the platform is synchronized to patient movement eliminates visual and proprioceptive information.