Objective: To review the current criteria for the interpretation of positional nystagmus (PN).
Design: Videonystagmography data on PN was collected for 90 patients presenting for balance testing with a history of vertigo or imbalance (excluding those diagnosed with benign paroxysmal positional vertigo). These were compared to normative data from 90 asymptomatic subjects. A literature review was carried out regarding threshold criteria for clinically significant PN. These were evaluated using the data collected.
Study sample: Clinic group: 90 patients; 37 male, 53 female. Age range 15-82 years. Normative group: Ninety subjects; 31 male, 59 female. Age range 21-79 years.
Results: PN was seen in 75.6% of the clinic group and in 50% of the normative group. The prevalence of nystagmus of slow phase velocity (SPV) > 3°/s was significantly higher in the clinic group than the normative group. The maximum SPV recorded in each position was greater from the clinic group than the normative group.
Conclusions: This study supports the use of normative thresholds for SPV for both horizontal and vertical PN. A normative threshold of >3°/s for horizontal and >7°/s for vertical nystagmus is proposed.
Keywords: Static; VNG; balance; nystagmus; positional; vestibular.