Evolution of vertigo episodes and clinical models
In the UMD group of patients, the mean incidence of annual episodes
reached a maximum value of 7.56 in the first year (SD ±13.68), 4.36
(±7.44) in the second year, and 2.94 (± 5.47) in the third and fourth
years of follow-up. Subsequently, the number of episodes stabilized to a
value of less than 2 episodes per year until the tenth year, and they
reduced until there was a cessation in the episodes in subsequent years
(figures 1 and 2).
In the subgroup of patients followed from the onset of the disease,
after analysing each case individually, specific criteria were defined
by which all these patients can be grouped into 3 behavioural or
evolutionary models based on the number of vertigo episodes/year
experienced during the first 10 years of the disease (Figure 3).
Model 1: Sudden onset with no further episodes from the fourth year
after disease onset. These patients experience episodes of vertigo in
consecutive years during the first four years of the disease (N=39,
44.8%).
Model 2: Sudden onset followed by a period of relapse. Episodes of
vertigo are experienced in the first four years of the disease
followed by a period with no episodes that lasted for at least
one-year, with a subsequent relapse or occurrence of episodes of
vertigo in one or more consecutive years (N=30, 34.5%).
Model 3: Multiple relapses throughout the course of the disease or
with a worst evolution. During the first 10 years of disease, episodes
of vertigo are recorded in at least 7 years, whether consecutively or
followed by intercritical periods of one or two years with no episodes
(N=18, 20.7%).