The mal de debarquement syndrome (MdDS), a continuous feeling of swaying, 
rocking, and/or bobbing, generally follows travel on the sea. The associated 
symptoms cause considerable distress. The underlying neural mechanisms are 
unknown, and to date there have been no effective treatments for this condition. 
Results in monkeys and humans suggested that MdDS was caused by maladaptation of 
the vestibulo-ocular reflex (VOR) to roll of the head during rotation. We 
studied 24 subjects with persistent MdDS (3 males, 21 females; 
19.1 ± 33 months). Physical findings included body oscillation at 0.2 Hz, 
oscillating vertical nystagmus when the head was rolled from side-to-side in 
darkness, and unilateral rotation during the Fukuda stepping test. We posited 
that the maladapted rocking and the physical symptoms could be diminished or 
extinguished by readapting the VOR. Subjects were treated by rolling the head 
from side-to-side while watching a rotating full-field visual stimulus. 
Seventeen of the 24 subjects had a complete or substantial recovery on average 
for approximately 1 year. Six were initially better, but the symptoms recurred. 
One subject did not respond to treatment. Thus, readaptation of the VOR has led 
to a cure or substantial improvement in 70% of the subjects with MdDS. We 
conclude that the adaptive processes associated with roll-while-rotating are 
responsible for producing MdDS, and that the symptoms can be reduced or resolved 
by readapting the VOR.