Positional Testing in Acute Vestibular Syndrome: a Transversal and Longitudinal Study

Area of Science:

• Neurology
• Ophthalmology
• Otorhinolaryngology

Background:

• Acute vestibular syndrome (AVS) presents diagnostic challenges, necessitating accurate differentiation between peripheral and central causes.
• Positional testing is a key component in evaluating vestibular dysfunction.

Purpose of the Study:

• To assess the diagnostic utility of positional testing in distinguishing peripheral AVS (pAVS) from central AVS (cAVS).
• To characterize nystagmus patterns in pAVS and cAVS using video-oculography.

Main Methods:

• Prospective observational study at a tertiary referral center.
• Video-oculography performed in upright, supine, and head-hanging positions for consecutive AVS patients.
• Evaluated positional modulation of spontaneous nystagmus and central paroxysmal positional nystagmus (CPPN).

Main Results:

• In supine position, 93% of pAVS patients showed direction-fixed nystagmus, compared to 33% of cAVS patients.
• cAVS patients exhibited diverse positional nystagmus patterns, including direction-fixed (stronger with fast phase) and direction-changing geotropic/apogeotropic.
• Head-hanging position revealed vertical CPPN in 33% of cAVS patients, with positional downbeat nystagmus and saccadic intrusions becoming chronic.

Conclusions:

• Acute direction-changing positional geotropic nystagmus, direction-fixed nystagmus stronger with fast phase, and head-hanging CPPN suggest central AVS.
• Chronic geotropic and apogeotropic nystagmus in AVS patients represent an underrecognized aspect of vestibular compensation.