Patients with a chronic vestibulopathy show unsteadiness in standing and walking, often without widening their base, and an inability to descend stairs without holding onto the banister. They complain of a particular type of imbalance, usually with movement but at times when standing still—a sensation that may be likened to being on the deck of a rolling ship (mal de barquement). Running and turning quickly are even more impaired, with lurching in all directions. The patient has great difficulty in focusing his vision on a fixed target when he is moving or on a moving target when he is either stationary or moving. When the body is in motion or the head is moved suddenly, objects in the environment may appear momentarily blurred or actually jiggle up and down or from side to side (oscillopsia). Driving a car or reading on a train is difficult or impossible; even when walking, the patient may need to stop in order to read a sign. These abnormalities indicate a loss of stabilization of ocular fixation by the vestibular system during body movements (the vestibular-ocular reflex, or VOR). An elderly person has difficulty compensating for these abnormalities. Proof that the gait of such persons with vestibulopathy is dependent on visual clues comes from their performance blindfolded or in the dark, when their unsteadiness and staggering increase to the point of falling. When standing with eyes closed, they sway more than normal but generally do not fall over (i.e., they do not have a Romberg sign). The diagnosis is confirmed by testing labyrinthine function (caloric and rotational testing, electronystagmography, and posture platform testing).
Chronic disorders of vestibular function in relation to gait disorders are most often the result of prolonged administration of aminoglycoside antibiotics or other toxic medications, which destroy the hair cells of the vestibular labyrinth. Vestibular suppressants, such as meclizine and similar medications, mostly anticholinergic and antihistaminic that are available over the counter, can lead to decreased function of the vestibular system, with a persistent gait disorder if used for more than a few weeks. This also occurs in some patients in the late stages of Ménière disease and, infrequently, for no definable reason. A colorful essay by a physician depicting the effects of the loss of the vestibular apparatus can be found by the author “JC” in the New England Journal of Medicine.
The literature is also replete with references to a “multimodal” gait disorder in the elderly that is the result of an ostensible aging of the vestibular organ, together with impaired proprioceptive function caused by distal neuropathy in the elderly, and impaired vision.
Toppling, meaning tottering and falling, occurs with brainstem and cerebellar lesions, especially in the older person following a stroke. In a related defect caused by a vestibular disorder, the patient may describe a sense of being pushed (pulsion) rather than of imbalance.
With midbrain strokes, toppling  falls tend to be backward (retropulsion). In patients with progressive supranuclear palsy (discussed in Chap. 38), where dystonia of the neck is combined with paralysis of vertical gaze and pseudobulbar features, unexplained unanticipated toppling is an early and prominent feature. The falls of progressive supranuclear palsy may derive from a disorder of the righting mechanism. In midbrain disease, including progressive supranuclear palsy, a remarkable feature is the lack of appreciation of a sense of imbalance. Toppling to one side is a feature of the lateral medullary syndrome, usually from infarction.
In the advanced stages of Parkinson disease, falling of a similar type may be a serious problem, but it is more surprising how relatively infrequently it occurs. The cause of the toppling phenomenon is unclear; it does not have its basis in weakness, ataxia, or loss of deep sensation. It appears to be a disorder of balance that is occasioned by precipitant action or the wrong placement of a foot and by a failure of the righting reflexes. Slowness of motor response is another factor.