2536 2537 Vertigo, when defined as an illusion of either oneself or 2538 the environment rotating, is a reliable symptom. It indi- 2539 cates involvement of the angular motion sensing system, 2540 i.e. the semicircular canals and their central projections. 2541 However, such involvement can occur from the labyrinth 2542 up to the vestibular cortex so that the site of the lesion will 2543 have to be presumed by additional symptoms (Table 62.1). 2544 Of particular value are hearing loss or tinnitus, usually 2545 indicating labyrinthine or VIII nerve involvement, and 2546 brainstem symptoms such as frank diplopia, facial numb- 2547 ness/weakness and dysarthria. Acute vertigo is terrifying 2548 and disabling and its duration can be a good guide to diag- 2549 nosis. In BPPV it is usually less than a minute; in migraine- 2550 associated vertigo (= vestibular migraine) it can be from 2551 minutes to many hours; in Ménière's disease a few hours; 2552 and in acute vestibular neuritis and consolidated brain- 2553 stem stroke a few days. 2554 2555 Illusions that one is moving linearly, such as falling ver- 2556 tically downwards or linear vertigo, can arise from dis- 2557 orders of the otolith system but it is extremely difficult to 2558 confirm selective otolith lesions and thus the clinical value 2559 of linear vertigo as a symptom is less well established.3, 4 2560 There is no evidence to classify postural symptoms, such 2561 2562 2563 2564 2565 ## TABLE 62.1 Additional symptoms helpful in the topographical diagnosis of balance disorders 2566 2567 2568

Site of lesion	Symptom	Comment
Peripheral (labyrinth or VIII nerve)	Tinnitus
	Hearing loss
Special cases
Labyrinthine	Ear fullness	Ménière's disease
CP angle	V, VI, VII cranial nerves	Extracanalicular growth
VII + VIII neuritis	Ext auditory canal vesicles + VII	Ramsay Hunt syndrome
Brainstem	Diplopia (III, IV, VI or skew deviation)
	Facial numbness (V)
	Difficulty swallowing, choking (IX, X)
	Slurred speech (XII, cerebellum)
	Uni-bilateral numbness, weakness, ataxia (long tracts, cerebellum)
	Unilateral deafness (+ ataxia)	AICA infarct
Cerebral hemisphere	Unilateral weakness, numbness
	Hemianopia (parieto-occipital lobe)	MCA/PCA
	Blindness (both occipital lobes)	Both PCAs
	Loss of consciousness
	Syncope, cardiac arrhythmia	Common
	Epilepsy	Rare (in vertigo)

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