VII Paroxysmal Positional Nystagmus

Characteristics and Possible Mechanisms of Direction-Reversing Nystagmus During Positional Testing in Patients With Benign Paroxysmal Positional Vertigo

OBJECTIVES

The occurrence of direction-reversing nystagmus during positional testing in patients with benign paroxysmal positional vertigo (BPPV) is not uncommon. Further in-depth analysis of the characteristics and possible mechanisms of direction-reversing nystagmus will help us to diagnose and treat BPPV more precisely. The study aimed to analyze the incidence and characteristics of direction-reversing nystagmus during positional testing in BPPV patients, evaluate the outcomes of canalith repositioning procedure for these patients, and further explore the possible mechanism of reversal nystagmus in BPPV patients.

STUDY DESIGN

Retrospective study.

SETTING

Single-center study.

PATIENTS

A total of 575 patients with BPPV who visited the Vertigo Clinic of our hospital between April 2017 and June 2021 were enrolled.

MAIN OUTCOME MEASURES

Dix-Hallpike and supine roll tests were performed. The nystagmus was recorded using videonystagmography. The characteristics of direction-reversing nystagmus and the possible underlying mechanism were analyzed.

RESULTS

Patients with BPPV who showed reversal nystagmus accounted for 9.39% (54 of 575) of all BPPV patients visiting our hospital during the same period, of which 5.57% (32 of 575) had horizontal semicircular canal BPPV (HC-BPPV), and 3.83% (22 of 575) had posterior semicircular canal BPPV (PC-BPPV). The maximum slow-phase velocities (mSPVs) of the first-phase nystagmus were greater in HC-BPPV and PC-BPPV patients with reversal nystagmus than those without (p = 0.04 and p = 0.01, respectively). In all HC-BPPV and PC-BPPV patients with reversal nystagmus, the mSPV of the first-phase nystagmus was greater than that of the second-phase nystagmus (p < 0.01). The duration of the second-phase nystagmus was longer than 60 seconds in 93.75% (30 of 32) of the HC-BPPV patients and 77.27% (17 of 22) of the PC-BPPV patients (p = 0.107, Fisher exact test). HC-BPPV and PC-BPPV patients with reversal nystagmus both required more than one canalith repositioning procedure compared with those without (HC-BPPV: 75 versus 28.13%, p < 0.001; PC-BPPV: 59.09 versus 13.64%, p = 0.002).

CONCLUSIONS

The cause of second-phase nystagmus in BPPV patients with direction-reversing nystagmus may be related to the involvement of central adaptation mechanisms secondary to the overpowering mSPV of the first-phase nystagmus.

Spontaneous Direction-Changing or Reversing Positional Nystagmus without Changing Head Position during Head-Roll/Head-Hanging Maneuvers: Biphasic Positional Nystagmus

BACKGROUND AND OBJECTIVES

Conflicting mechanisms have been reported about spontaneous reversal of positional nystagmus during head-roll maneuver in patients with benign paroxysmal positional vertigo (BPPV). The objective of this study is to review the reports about the characteristics and possible mechanisms of reversing positional nystagmus and to present seven new cases.

SUBJECTS AND METHODS

Seven cases (5 males, 2 females; 4 left-sided, 3 right-sided) were recruited among 732 patients with BPPV seen outpatient clinic between 2009 and 2019. Diagnosis of lateral canal canalolithiasis was confirmed when transient geotropic nystagmus was documented during head-roll test. Reversing positional nystagmus was analyzed in each case and clinical characteristics of the patients were documented.

RESULTS

The age of patients was ranging between 30 to 64 years (46.44±10.91). Duration of symptoms was short (21.34±19.74). Six of them had a story of head trauma. Initial latency was short. First, intense geotropic nystagmus was observed following provocative head-roll position on the affected side. There was short "silent phase". Then, a longer second-phase of reversed nystagmus was noted. Total duration of nystagmus was 78.40±6.82 seconds. Maximal slow phase velocity was 24.05±6.34 deg/sec. All patients were cured with barbeque maneuver.

CONCLUSIONS

Ipsilateral reversing positional nystagmus during head-roll maneuver is due to lateral canal canalolithiasis. Mechanism is likely to be due to endolymphatic double flow. Bilateral cases may be due to simultaneous co-existence of canalolithiasis and cupulolithiasis. Longer recording of nystagmus is recommended not to miss the cases with spontaneous direction-changing positional nystagmus.

Experimental model of benign paroxysmal positional vertigo with biphasic nystagmus using isolated semicircular canals

CONCLUSIONS

The co-existence of cupulolithiasis and canalolithiasis might be a possible mechanism for the spontaneous inversion of positional nystagmus.

OBJECTIVE

To investigate the mechanism of spontaneous inversion of nystagmus direction without a positional change in experimental models of co-existing cupulolithiasis and canalolithiasis.

METHODS

Co-existing canalolithiasis and cupulolithiasis models were prepared using the bullfrog posterior semicircular canal (PSC). Ten bullfrogs were used. The ampullary nerve discharges were recorded as compound action potentials (CAPs). First, an otoconial mass was placed on the cupula to produce cupulolithiasis. Subsequently, another otoconial mass was introduced into the canal lumen to produce canalolithiasis. Decremental time constants for cupulolithiasis and incremental time constants for canalolithiasis were determined.

RESULTS

At first the CAPs increased and continued for a long time when the cupulolithiasis was generated. Subsequently the CAPs were suppressed by creating canalolithiasis. Finally, the CAPs increased again after the motion of otoconia inside the canal lumen stopped. The decremental time constant for cupulolithiasis was significantly longer than the incremental time constant for canalolithiasis.

Lying-down nystagmus and head-bending nystagmus in horizontal semicircular canal benign paroxysmal positional vertigo: are they useful for lateralization?

BACKGROUND

Lateralization of horizontal semicircular canal benign paroxysmal positional vertigo (HSC-BPPV) is very important for successful repositioning. The directions of lying-down nystagmus (LDN) and head-bending nystagmus (HBN) have been used as ancillary findings to identify the affected sites. This retrospective study was performed to evaluate the lateralizing values of LDN and HBN using clinical and laboratory findings for lateralizing probabilities in patients with HSC-BPPV.

METHODS

For 50 HSC-BPPV patients with asymmetric direction-changing horizontal nystagmus (DCHN) during the head-rolling test (HRT) using Frenzel goggles, the directions of LDN and HBN were evaluated and compared to those determined by video-oculography. Directional LDN was defined as the contralesional direction of nystagmus in geotropic types and the ipsilesional direction in apogeotropic types. Directional HBN was defined as the opposite direction relative to directional LDN. We also analyzed LDN and HBN in 14 patients with a history of ipsilesional peripheral vestibulopathy, caloric abnormality or conversion from other types of BPPV (such as probable localized HSC-BPPV, pro-BPPV).

RESULTS

LDN and HBN were seen in 68% (34/50) and 76% (38/50) of patients, respectively. Of these, 19 (55.9%), and 28 (73.7%) patients showed directional LDN and HBN, respectively. The proportion of patients with directional LDN and HBN was much smaller among the pro-BPPV patients (4/12 for LDN, 3/10 for HBN).

CONCLUSIONS

LDN and HBN did not seem to predict lateralization in patients with HSC-BPPV. To improve the prediction of lateralization of HSC-BPPV, it is necessary to modify the maneuvers used to elicit LDN or HBN, especially in cases of symmetric DCHN during HRT.

The assessment and management of the dizzy patient

A significant number of individuals are affected by symptoms of dizziness. It is the most common complaint among patients over 75 years of age. A large number of these patients seek counsel from their physicians. It is imperative for the evaluating physician to obtain a thorough history and perform a complete physical exam. The proper diagnostic studies must also be obtained to confirm or rule out particular diagnoses. The physician should never assume that the dizziness is the result of normal aging prior to ruling out pathologic conditions.

Paroxysmal positional vertigo

Paroxysmal positional vertigo (PPV) is the peripheral vertiginous syndrome that is most frequently encountered in clinical practice. It is characterised by paroxysmal vertiginous attacks that are triggered by head movements and last no more than a few seconds, and is often accompanied by nausea and vomiting. The aim of this review is to provide a complete and updated description of the two principal manifestations of the syndrome: posterior semicircular canal (PSC-PPV) and horizontal semicircular canal PPV (HSC-PPV).

Positional vertigo and ageotropic bidirectional nystagmus

A strong paroxysmal positional horizontal nystagmus accompanied by symptoms similar to those of paroxysmal positional vertigo (PPV) can be observed in a small fraction of patients who have positional vertigo. This nystagmus may be a lateral canal variant of PPV. We evaluated nine patients who had episodes of prolonged, intense positional vertigo provoked by lateral movements of the head while in the supine position. The nystagmus appeared as horizontal and was directed toward the uppermost ear (ageotropic) when the head was rotated to either side (bidirectional). The duration of nystagmus lasted more than 1 minute in all the cases, although it presented a progressive decrease in the velocity of the slow component. The clinical and electronystagmographic features of this syndrome lead us to propose a different form of horizontal canal PPV associated with a paroxysmal positional ageotropic and bidirectional nystagmus, probably caused by a "heavy cupula" as a result of deposits of extraneous bodies (otolithic?) or by a cupula denser than the endolymph.

Benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo (BPPV) has received renewed clinical interest. At the Johns Hopkins Otological Vestibular Laboratory, 781 patients were tested on more than one occasion between September 1976 and November 1992. Of these patients, 187 (24%) were found to have positional nystagmus consistent with a diagnosis of BPPV. A retrospective analysis of these patients' records, including vestibular test and eye movement reports, audiograms, questionnaires, and hospital charts was performed. After this review, the nystagmus, initially diagnosed as due to BPPV, was believed to be a manifestation of another disease process in 36 cases. Of the remaining 151 cases, 52 (34%) presented with no significant preceding disorder and have been termed primary BPPV. In the remaining 99 patients we found coexisting or associated disorders which included Meniere's disease, head trauma, prior ear surgery, vestibular neuronitis, migraine, and others. Forty-five of these 151 patients (31%) had an associated diagnosis of Meniere's disease. To our knowledge a significant association between Meniere's disease and BPPV has not been reported. A review of the literature with discussion of BPPV and the associated disorders is offered.

Benign paroxysmal positional vertigo of posterior semicircular canal: results in 160 cases treated with Semont's maneuver

One hundred sixty patients affected by benign paroxysmal positional vertigo of the posterior semicircular canal were treated with Semont's maneuver. Complete recovery after only one session was achieved in more than 50% of cases. After a maximum of five sessions, almost all patients had recovered; only 8 needed another kind of rehabilitation. No drug therapy was required for any patient.

Particle repositioning maneuver for benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo is a common, most often self-limited, vestibular end organ disorder that in some cases may be quite disabling. Recent evidence suggests that some, if not most, cases result from free-floating posterior semicircular canal endolymph particles. We postulate that the particle repositioning maneuver displaces these particles from the posterior canal through the common crus into the utricle, where they no longer induce pathologic responses. Our report focuses on 38 consecutive patients treated with this simple bedside technique during a 10-month period. On follow-up, 26 patients (68.4%) were free of disease, 4 (10.5%) were significantly improved, 4(10.5%) remained unchanged, and 4(10.5%) were lost to follow-up. Of the 4 patients who remained unchanged, 2 underwent successful posterior semicircular canal occlusions. The direction of the nystagmus during the second stage of the maneuver appears important in predicting the efficacy, with reversal of nystagmus denoting a poor response. These findings provide additional insight into the pathophysiology of this disorder.

Positional nystagmus

Positional nystagmus (PN) appears in certain positions of the head. The peripheral type of PN is a paroxysmal nystagmus which appears after a latent period and which has both adaptation and fatigability. Positional vertigo of the peripheral type can sometimes be related to middle ear affections or head trauma, causing detachment of otoconia in the vestibular apparatus. The condition can also be correlated to disturbed blood circulation, ageing, vascular loops and Borreliosis. PN of the central type is direction changing and does not have a latent period or adaptation and fatigability. Etiological factors are drugs, posterior fossa tumours, vascular disturbance and multiple sclerosis.

Nystagmus of paroxysmal positional vertigo: some new insights

In most of our patients with paroxysmal positional vertigo, the paroxysm was usually short (less than 25 or 30 seconds). With the eyes deviated toward the lowermost ear, the observed nystagmus was rotatory-linear and the fast phases beat toward this ear. When the eyes were deviated to the opposite side, the fast phase of nystagmus was mainly upward linear-oblique. In a small number of patients, however, some unusual findings were observed: the nystagmus was the usual rotatory-linear, but the duration was much longer; or the nystagmus was purely horizontal; or the nystagmus was rotatory-linear, but the fast phases were in opposite direction to that usually observed. These data suggest that: the observed paroxysmal nystagmus seems compatible with excitation of the posterior or horizontal semicircular canal of the lowermost ear, or the superior canal of the uppermost ear; and singular nerve section is an appropriate treatment only if the observed paroxysmal nystagmus is compatible with excitation of a posterior semicircular canal.

Positional nystagmus

Positional nystagmus may be persistent or transitory. Of the persistent forms, type I refers to nystagmus changing direction in different head positions and type II to nystagmus beating in a single direction. Both types may denote either peripheral or central abnormality. Transitory, or paroxysmal, positional nystagmus is classified as type III, and the history and physical and electronystagmographic features of its accompanying vertigo and nystagmus permit subdivision into typical and atypical forms. Guidelines are given for the differentiation of typical and atypical forms. In the great majority of cases type III positional nystagmus denotes a harmless inner ear disturbance, but the occasional serious intracranial lesion is also causative. Most instances of the latter, but not all, will fit in the atypical group. A case is reported of vermis metastasis with presenting features of postural vertigo and paroxysmal downbeat positional nystagmus.

Auditory brain stem responses in patients with vertigo

Sixty-two patients with vertigo were examined with ABR. Eight of the 30 patients with vestibular neuronitis had abnormal ABR indicating brain stem dysfunction. Most of the patients with abnormal ABR showed continued ABR abnormality after recovery from the disease. Only one patient with epidemic vertigo had abnormal ABR, the remaining 15 patients had no signs of brain stem involvement. All 16 patients with benign positional vertigo had normal ABR.

Nystagmus of paroxysmal positional vertigo

During attacks of paroxysmal positional vertigo in 12 patients, nystagmus in different gaze positions was observed visually and recorded by electronystagraphy (eyes open, fixating). Visually observed eye movement was similar in all cases, with oblique (upward and horizontal) and rotatory (clockwise during leftward movement) components in fast phase; rotation dominated on ipsilateral gaze (toward the lower ear) and oblique movement dominated on contralateral gaze. However, ENG recordings showed greater variability and were often inconsistent with visual observation; the horizontal component often reversed with change in gaze position, and dissociated eye movements, as well as down-beating nystagmus, were sometimes seen. More sophisticated measurement and strict attention to gaze position is required to resolve these discrepancies.

Some observations on the localizing significance of ear-dependent positional nystagmus

Seventy-one patients who demonstrated unilateral ear-dependent positional nystagmus and unilateral labyrinthine weakness were studied to test the hypothesis that ear-dependent positional nystagmus almost always occurs on the side of unilateral labyrinthine impairment. Little, if any, correlation was found between these two parameters. The results of this study with regard to the critical question of selecting the correct ear for surgery in patients with incapacitating benign paroxysmal postural vertigo are discussed.

Vestibular compensation and nystagmus

In healthy young subjects barbiturate induced vestibular nystagmus was sequentially studied with repeated electronystagmographic recordings. The analysed data together with our earlier studies indicated that, except for vertical nystagmus, spontaneous and different types of positional nystagmus by themselves are not diagnostic of site of lesion. The transition from spontaneous to positional to paroxysmal nystagmus observed in follow up studies of several of these cases indicates that these various types of vestibular nystagmus are likely a measure and reflection of different degrees of vestibular decompensation.

New dimensions of benign paroxysmal positional vertigo

Twenty-nine patients who demonstrated the classic nystagmus of benign paroxysmal positional vertigo in the provocative, ear-down position had a high incidence of concurrent symptoms. These included vertigo provoked by arising, bending over, head rotation, linear acceleration, and vertical oscillation. Some have not been reported previously in relation to this syndrome. Elimination of both concurrent and classic symptoms via singular neurectomy in nine patients indicates a common pathophysiologic mechanism, probably involving cuplolithiasis in the posterior semicircular canal. These concurrent symptoms should be considered part of the syndrome.