The direction of nystagmus is important for the diagnosis of central paroxysmal positioning nystagmus (cPPV)

Abstract

Head-positioning maneuvers can lead to paroxysmal nystagmus and vertigo, which are usually due to a peripheral vestibular disorder like, for example, benign paroxysmal positioning vertigo (BPPV). They are less commonly caused by a central lesion (central paroxysmal positioning nystagmus, cPPV). While many typical features do not permit differentiation between BPPV and cPPV, for example, latency, course, and duration of nystagmus and vertigo during an attack, the direction of nystagmus often does. The nystagmus in BPPV always beats in the direction aligned to the affected semicircular canal plane, i.e., horizontal for the horizontal canal and vertical-torsional for the vertical canals. Any other direction (paroxysmal torsional, upbeat, or downbeat nystagmus) indicates a central origin. Three cases of cPPV exhibiting nystagmus in the latter directions are presented. In one of the cases with paroxysmal downbeat nystagmus and vertigo, all other parts of the neurological examination and brain imaging initially showed no lesion in the posterior fossa. The direction of nystagmus was the only sign that indicated a central origin.

Central Positional Nystagmus: A Systematic Literature Review

“…A repeat of the positional test (to observe a fatigue effect) was reported in 28 (34.1%) subjects (6,12,13,15,17,19,22,31,34).…”

“…CPN was triggered only upon lying supine with either ear down in 26 (31.7%) cases (6, 7, 13, 15, 20-24, 26, 28, 32-35) and only upon SHH in 3 (3.7%) (6,31,33). In one case, CPN was triggered by SHH and horizontal head rotation with either ear down (26).…”

“…PN was quantified in 51 (62.1%) participants, 35 (42.7%) with VNG (4,15,(20)(21)(22)(23)(24)(25)(26)35), 15 (18.3%) with electronystagmography (11,14,18,33), and 1 (1.2%) using three-dimensional scleral induction coil (6). It is uncertain how the nystagmus was recorded in the remaining 31 participants (37.8%), presumably from direct observation during clinical examination (6,7,12,13,16,17,19,(30)(31)(32)(33)(34).…”

“…The study set included 11 case series (6,7,11,26,(30)(31)(32)(33)(34)(35)(36) and 17 case reports (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(27)(28)(29). This review did not identify any controlled studies relevant to the diagnosis of central positional vertigo/nystagmus.…”

“…Positional nystagmus upon horizontal plane (roll) head movements while supine was reported in 41 (50%) cases (6,7,13,15,18,20,22,24,28,29,32,33), at least 18 (43.9%) of which were atypical in terms of direction (6,7,13,15,18,32,33).…”