What is a drop attack? 

A drop attack is a sudden fall without loss of consciousness. 

Drop attacks stem from diverse mechanisms, including orthopedic causes (for example, leg weakness and knee instability), hemodynamic causes (for example, transient vertebrobasilar insufficiency, a type of interruption of blood flow to the brain), and neurologic causes (such as epileptic seizures or unstable vestibular function), among other reasons.

Drop attacks and Meniere's? 

Drop attacks that have a vestibular origin within the inner ear may be experienced by some people in the later stages of Ménière's disease (these may be referred to as Tumarkin [drop] attacks, or as Tumarkin's otolithic crisis).

A Meniere’s drop attack occurs suddenly and without warning and there is loss of muscle tone in the legs so that the person can fall. There is no loss of consciousness. The person may feel some vertigo but this is milder than the Meniere’s attacks. In the elderly, there can be broken bones. 

It is not safe to drive a car or operate machinery until it is certain that the drop attacks have ceased.

Meniere’s drop attacks only occur in the end stage of Meniere’s disease when there is a constant and severe hearing loss when the classic attacks of rotational vertigo have ceased. The drops attacks can continue for up to 3 years. 

It may be necessary to reduce the vestibular function in the affected ear by gentamicin injections or even a surgical destructive procedure (such as labyrinthectomy or vestibular nerve section). Older people may have to endure the episodes until they fizzle out as loss of any balance function can cause instability.

(Source: Professor William Gibson)