Pseudo-Spontaneous and Head-Shaking Nystagmus in Horizontal Canal Benign Paroxysmal Positional Vertigo

Abstract

HSN is more common and mostly contralesional in apogeotropic HC-BPPV. HSN may be a lateralizing sign in apogeotropic HC-BPPV. Different prevalence and patterns of HSN in apogeotropic and geotropic HC-BPPV suggest dissimilar cupular dynamics in those disorders.

Benign paroxysmal positional vertigo: Diagnostic criteria

“…Besides positional nystagmus, pseudospontaneous nystagmus may also be observed in the upright head position beating typically to the affected ear [1,12,52]. Pseudospontaneous nystagmus is a form of positional nystagmus that happens to occur with the head in the upright position, making it appear superficially similar to spontaneous nystagmus.…”

“…Besides positional nystagmus, pseudospontaneous nystagmus (see also comment to 2.3) may also be observed in the upright head position beating either ipsilesional or contralesional [1,52].…”

Lateral canal BPPV with Pseudo-Spontaneous Nystagmus masquerading as vestibular neuritis in acute vertigo: A series of 273 cases

“…The ED medical approach is usually centred on a basic neurological exam that includes spontaneous nystagmus observation and the pharmacological antiemetic treatment of the associated symptoms such as vomiting and nausea. Many patients also receive a CT scan, which is often still the only imaging exam available at most ED where MRI remains expensive and unfortunately not rou- [1][2][3]5,6,[9][10][11][12][13][23][24][25][26]28,29,32,33]. Such a nystagmus could be mistaken for a 'spontaneous' one, but it is a direction changing nystagmus because it is strongly modulated by head position, therefore it has been most properly defined as a 'Pseudo-Spontaneous Nystagmus' -PSN.…”

“…Scientific literature, while bringing many clinical reports of PSN [1,2,4,5,[9][10][11][12][13][23][24][25][26]28,29,33], does not report a complete explanation of the pathophysiology of its long-term yet. Nevertheless, we could hypothesize that the very long duration of the nystagmus observed in the upright position can be explained by assuming a balance of forces more or less equal in size and acting in opposite directions on the otolithic mass.…”

Benign Paroxysmal Positional Vertigo: What We Do and Do Not Know

“…Furthermore, patients with canalolithiasis may have pseudospontaneous nystagmus that beats toward the affected side. 42 On the other hand, with cupulolithiasis, pseudospontaneous nystagmus, with its modulation by the orientation of the head in the sagittal plane, has been related to the alignment of the cupula relative to the gravity vector. With the cupulolithiasis theory, however, the orientation of the plane of the cupula in the canal is critical.…”