Chapter 022. Dizziness and Vertigo (Part 4) doc

Chapter 022. Dizziness and Vertigo (Part 4) a In Ménière's disease, the direction of the fast phase is variableVertigo may be a manifestation of a migraine aura (Chap. 15), but some patients with migraine have episodes of vertigo unassociated with their headaches. Antimigrainous treatment should be considered in such patients with otherwise enigmatic vertiginous episodes. Vestibular epilepsy, vertigo secondary to temporal lobe epileptic activity, is rare and almost always intermixed with other epileptic manifestations.Psychogenic Vertigo This is sometimes called phobic postural vertigo and is usually a concomitant of panic attacks (Chap. 386) or agoraphobia (fear of large open spaces, crowds, or leaving the safety of home). It should be suspected in patients so "incapacitated" by their symptoms that they adopt a prolonged housebound status. Most patients with organic vertigo attempt to function despite their discomfort. Organic vertigo is accompanied by nystagmus; a psychogenic etiology is almost certain when nystagmus is absent during a vertiginous episode. The symptoms often develop after an episode of acute labyrinthine dysfunction. Miscellaneous Head Sensations This designation is used, primarily for purposes of initial classification, to describe dizziness that is neither faintness nor vertigo. Cephalic ischemia or vestibular dysfunction may be of such low intensity that the usual symptomatology is not clearly identified. For example, a small decrease in blood pressure or a slight vestibular imbalance may cause sensations different from distinct faintness or vertigo but that may be identified properly by provocative testing techniques (see below). Other causes of dizziness in this category are hyperventilation syndrome, hypoglycemia, and the somatic symptoms of a clinical depression; these patients should all have normal neurologic examinations and vestibular function tests. Depressed patients often insist that the depression is "secondary" to the dizziness. Approach to the Patient: Dizziness and Vertigo The most important diagnostic tool is a detailed history focused on the meaning of "dizziness" to the patient. Is it faintness (presyncope)? Is there a sensation of spinning? If either of these is affirmed and the neurologic examination is normal, appropriate investigations for the multiple causes of cephalic ischemia, presyncope (Chap. 21), or vestibular dysfunction are undertaken. When the meaning of "dizziness" is uncertain, provocative tests may be helpful. These office procedures simulate either cephalic ischemia or vestibular dysfunction. Cephalic ischemia is obvious if the dizziness is duplicated during maneuvers that produce orthostatic hypotension. Further provocation involves the Valsalva maneuver, which decreases cerebral blood flow and should reproduce ischemic symptoms. Hyperventilation is the cause of dizziness in many anxious individuals; tingling of the hands and face may be absent. Forced hyperventilation for 1 min is indicated for patients with enigmatic dizziness and normal neurologic examinations. The simplest provocative test for vestibular dysfunction is rapid rotation and abrupt cessation of movement in a swivel chair. This always induces vertigo that the patients can compare with their symptomatic dizziness. The intense induced vertigo may be unlike the spontaneous symptoms, but shortly thereafter, when the vertigo has all but subsided, a lightheadedness supervenes that may be identified as "my dizziness." When this occurs, the dizzy patient, originally classified as suffering from "miscellaneous head sensations," is now properly diagnosed as having mild vertigo secondary to a vestibulopathy. Patients with symptoms of positional vertigo should be appropriately tested (Table 22-1). A final provocative and diagnostic vestibular test, requiring the use of Frenzel eyeglasses (self-illuminated goggles with convex lenses that blur out the patient's vision, but allow the examiner to see the eyes greatly magnified), is vigorous head shaking in the horizontal plane for about 10 s. If nystagmus develops after the shaking stops, even in the absence of vertigo, vestibular dysfunction is demonstrated. The maneuver can then be repeated in the vertical plane. If the provocative tests establish the dizziness as a vestibular symptom, an evaluation of vestibular vertigo is undertaken. . Chapter 022. Dizziness and Vertigo (Part 4) a In Ménière's disease, the direction of the fast phase is variableVertigo may be a manifestation of a. examinations and vestibular function tests. Depressed patients often insist that the depression is "secondary" to the dizziness. Approach to the Patient: Dizziness and Vertigo . epileptic activity, is rare and almost always intermixed with other epileptic manifestations.Psychogenic Vertigo This is sometimes called phobic postural vertigo and is usually a concomitant