One record was excluded because of poor scan quality. Of the 1,091 remaining visits for dizziness over the study period, 887 (81.3%) had a nystagmus exam documented. The median age of the cohort was 54.4 years (IQR 41.1-68.8), and 565 (63.7%) were female. A peripheral vestibular diagnosis was given in 140 (15.8%) of the 887 visits (4.1% BPPV, 11.7% vestibular neuritis). No cases were documented to have horizontal or anterior canal BPPV.
Nystagmus was present in 185 (20.9%) of the 887 visits, and one or more descriptive details were also recorded in 137 (74.0%) (). Information about the direction of nystagmus was the most commonly recorded detail, found in almost two-thirds. However, only about half of the direction descriptors indicated a specific direction (e.g., “left,” “right,” “up,” “down”); the remainder were non-specific descriptors (e.g., “horizontal,” “lateral”). Comments about the temporal profile (e.g., “brief,” “fatigable,” or “persistent”) or the amplitude/intensity (e.g., “mild,” “slight,” “rapid”) of the nystagmus were noted in less than one-third of records. None mentioned the effects of fixation removal.
Characteristics of nystagmus in 887 ED visits for dizziness which had a nystagmus assessment recorded (i.e., documentation of nystagmus as present or absent).
Comments indicating the nystagmus was present on gaze testing were more common (35.7%) than comments about whether the nystagmus was spontaneously present in the primary position (i.e., looking straight ahead) (3.2%). A Dix-Hallpike test was mentioned in 46 (5.2%) of the 887 visits. However, nystagmus was directly linked to the Dix-Hallpike test (e.g., “nystagmus triggered by the Dix-Hallpike test”) in only seven (0.8%) of the 887 visits. For the remainder of the Dix-Hallpike tests recorded, the test result did not mention nystagmus. Instead, the test result was either not recorded (n = 2), recorded only as “positive,” (n = 24) or “negative” (n = 13).
Only one visit included a higher-order label (i.e., “central,” “peripheral,” or “physiological”) to describe the overall nystagmus pattern. The documented description of the nystagmus enabled neuro-otology raters to draw any inference (i.e., categorized as “strongly agree” or “somewhat agree” that an inference could be made) about the localization or etiology in only 10 (5.4%) of the 185 visits with nystagmus present (). Of the visits with nystagmus present and a description that did not enable a meaningful inference (n = 175), most (128, 73.1%) had no other clinical localizing features recorded (e.g., auditory abnormalities, or other focal neurologic symptoms or signs) to inform the differential diagnosis.
Figure 2 Results of the assessment about agreement with the statement: “The recorded nystagmus description enabled a meaningful inference about the localization or the cause of the nystagmus.” Population = visits with documentation of presence (more ...)
For visits receiving a peripheral vestibular diagnosis (i.e., BPPV or vestibular neuritis), most of the nystagmus descriptions (113 of 140, 80.7%) were against the rendered diagnosis (i.e., either “strongly” or “somewhat” against) (). The most common reason that reported nystagmus findings were against the diagnosis was documentation of nystagmus being absent, even though BPPV and vestibular neuritis are diagnosed by confirming the presence of a characteristic nystagmus. However, even when nystagmus was documented to be present, 54.2% (32 of 59) of the descriptions were against the diagnosis rendered.
Table 2 The extent to which nystagmus documentation was “for” or “against” the diagnosis in visits receiving a peripheral vestibular diagnosis (i.e., benign paroxysmal positional vertigo or vestibular neuritis/labyrinthitis) from (more ...)