How to induce nystagmus (involuntary eye movement) on physical examination?

From the Guidelines

To trigger nystagmus on exam, the Dix-Hallpike maneuver is the most effective method, which involves quickly moving the patient from a sitting position to a supine position with their head turned 45 degrees to one side and neck extended 20 degrees, holding this position for 30 seconds while observing the eyes for nystagmus 1. This technique is used to test for positional nystagmus associated with benign paroxysmal positional vertigo (BPPV). The Dix-Hallpike maneuver should be repeated with the opposite ear down if the initial maneuver is negative. Some key points to consider when performing the Dix-Hallpike maneuver include:

• Starting with the patient sitting upright on the examination table
• Quickly moving them into a supine position with their head hanging off the edge of the table and turned 45 degrees to one side
• Holding this position for 30 seconds while observing the eyes for nystagmus
• Repeating the maneuver with the opposite ear down if the initial maneuver is negative Other methods to trigger nystagmus include the roll test, caloric testing, optokinetic nystagmus, and gaze-evoked nystagmus. However, the Dix-Hallpike maneuver is the most effective method, as supported by the clinical practice guideline: benign paroxysmal positional vertigo (update) 1. It is essential to note that these techniques work by stimulating the vestibular system or challenging the brain's ability to maintain stable vision, which can reveal underlying vestibular or neurological disorders when nystagmus appears. The Semont Liberatory Maneuver, as described in the study by 1, can also be used to trigger nystagmus, but the Dix-Hallpike maneuver is the most recommended method. In real-life clinical practice, it is crucial to prioritize the patient's safety and comfort during the examination, and to be aware of any potential complications or contraindications to the maneuver.

From the Research

Triggering Nystagmus on Exam

To trigger nystagmus on exam, the Dix-Hallpike test is commonly used. This test involves:

• Rapidly moving the patient from a sitting position to a "head hanging" position, where the patient's head is at least 10 degrees below horizontal 2
• Testing the posterior semicircular canals initially, and if no vertigo or nystagmus is elicited, testing the horizontal semicircular canals by laying the patient on each side 2
• Repeating the tests of the posterior semicircular canals if no vertigo or nystagmus is elicited, as failure to do so may result in a falsely negative test 2

Characteristics of Dix-Hallpike Test Induced Nystagmus

The characteristics of nystagmus induced by the Dix-Hallpike test can vary, including:

• Vertical downward component, which is common in patients with benign paroxysmal positional vertigo (BPPV) 3
• Horizontal beating nystagmus, which can be observed in patients with horizontal canal BPPV 4
• Direction-changing positional nystagmus, which can be observed in patients with geotropic or apogeotropic HC-BPPV 4

Clinical Implications

The clinical implications of triggering nystagmus on exam include:

• Diagnosis of BPPV, which can be objective (with nystagmus) or subjective (without nystagmus) 5
• Determining the subtype and affected side of HC-BPPV, which can be done by analyzing the direction of horizontal beating nystagmus 4
• Interpreting the results of the Dix-Hallpike test and the supine head-roll test concomitantly to reach a correct and comprehensive diagnosis and apply appropriate treatment in BPPV 6