Introduction
Vertical nystagmus in primary gaze is a sign of central nervous system dysfunction.Reference Baloh and Spooner1 However, positional vertical nystagmus can be due to either central or peripheral pathology. A peripheral problem is indicated by normal radiology, together with the presence of latency, adaptation and habilitation of transient nystagmus associated with a brief and intense sense of vertigo and reversal of nystagmus when the patient changes to a sitting position from a head-hanging position. In addition, spontaneous resolution is less likely in central type positional nystagmus.
Although the basic points that help to differentiate peripheral from central positional nystagmus are quite obvious, vertical positional nystagmus of peripheral origin is not well known; there have only been occasional reports because of the rarity of this condition. A study by Honrubia et al. was one of the first to indicate the possibility of anterior canal involvement in patients with down-beating vertical nystagmus during the straight head-hanging manoeuvre.Reference Honrubia, Baloh, Harris and Jacobson2 Bertholon et al. reported 50 patients with positional down-beating nystagmus. Of those, 12 patients had no pathology on radiological examination and were grouped as idiopathic type. The features of positional nystagmus were different and were assumed to be due to anterior canal canalolithiasis.Reference Bertholon, Bronstein, Davies, Rudge and Thilo3 However, the existence of anterior canal benign paroxysmal positional vertigo (BPPV) has been challenged by other authors.Reference Schratzenstaller, Wagner-Manslay, Strasser and Arnold4 Later studies indicated that provoked vertical nystagmus during the head-hanging manoeuvre may be due to bilateral, simultaneous stimulation of the posterior canals.Reference Imai, Takeda, Sato, Sekine, Ito and Nakamea5, Reference Balatsouras, Koukoutsis, Ganelis, Korres and Kaberos6
Stimulation of lateral, anterior and posterior canals is likely to occur while lying back. Patients with lateral canal BPPV frequently experience a sudden sense of spinning when they turn their head to either side while lying down, or when they bend their head forward or backward intentionally or unintentionally, such as when falling asleep, reading a newspaper or lying down from a sitting position. Those patients may have brief episodes of nystagmus associated with these day-to-day activities.
From these observations, Nuti et al. and Asprella-Libonati proposed a test to confirm the diagnosis of lateral canal BPPV in the affected canal.Reference Nuti, Vannucchi and Pagnini7, Reference Asprella-Libonati8 During the seated–supine positional test, affected patients have horizontal nystagmus beating to the healthy side in canalolithiasis and to the affected side in cupulolithiasis. However, vertical nystagmus can present in exceptional conditions when the patients are lying down.
We present up-beating vertical nystagmus during the seated–supine positional test in 12 patients with BPPV. The pattern of nystagmus in each case and the pathophysiological mechanism are reviewed.
Materials and methods
A total of 190 patients with BPPV symptoms confirmed by video-nystagmography (Micromedical Technologies, Chatham, Illinois, USA), who presented between 2009 and 2012, were enrolled in the study. Those with hearing loss, tinnitus, spontaneous nystagmus, abnormal ear drum, or other vestibular or neurological problems, and those who had used medication prior to the test which could affect the vestibular system, were excluded. There were 77 men and 113 women, aged from 14 to 84 years (mean, 44.13 ± 13.61 years). Patients were tested with infrared video-nystagmography and audiogram at the time of initial admission, and with video-nystagmography alone after resolution of the symptoms following the therapeutic manoeuvres. All patients had normal otoscopic examination findings, normal hearing thresholds and no problems other than BPPV. Informed consent was obtained from all patients.
Patients were first tested with video-nystagmography for spontaneous nystagmus in the seated position, with and without an optical target. Diagnosis of posterior canal BPPV was based on medical history and the presence of clockwise or counter-clockwise rotatory nystagmus (torsional, up-beating) during the head-hanging manoeuvre. Diagnosis of superior canal BPPV was based on medical history and the presence of clockwise or counter-clockwise rotatory nystagmus (torsional, down-beating) during the head-hanging manoeuvre. Diagnosis of lateral canal BPPV with canalolithiasis or cupulolithiasis was based on medical history and the presence of geotropic or ageotropic nystagmus (horizontal) during the roll-on manoeuvre.
The type, duration and direction of nystagmus were recorded with an infrared wireless video camera. The side affected by the lateral canal BPPV was determined according to the severity of nystagmus (which was worse on the affected side if it was canalolithiasis and worse on the healthy side if it was cupulolithiasis) as seen on: the video-nystagmography recording, the supine–seated positional test, the head-pitch test, or the patient's report if the others were not helpful (Figure 1).
A 35-second recording of the seated–supine positional (straight head-hanging) test for patient number one, showing up-beating nystagmus. Note the vertical nystagmus on vertical recordings (lower line; LV) without a torsional component as the horizontal recording (upper line; LH) is silent.
Patients with posterior canal BPPV were treated with the Epley manoeuvre, and patients with lateral canal BPPV were treated with either the Barbeque or Semont manoeuvre. Patients who had recurrent symptoms after manoeuvres were monitored by video-nystagmography, performed within one week of the manoeuvre, and subjected to further therapeutic manoeuvres as dictated by video-nystagmography until resolution of the symptoms. Magnetic resonance imaging (MRI) was ordered for all patients with atypical BPPV.
Patients were grouped according to whether they had posterior canal BPPV, lateral canal BPPV (differentiating cupulolithiasis and canalolithiasis), superior canal BPPV or multiple canal BPPV. Symptom duration, aetiology and recurrence (patients who had been cured after one single manoeuvre vs those who needed to be treated with several manoeuvres) were analysed for each group. A one-way analysis of variance was used for comparative analysis of the groups. Statistical significance was set at p < 0.05.
Results
Of the 190 patients, 173 had single-canal BPPV, of which 70 had posterior canal BPPV, 14 had anterior canal BPPV and 89 had lateral canal BPPV (50 canalolithiasis and 39 cupulolithiasis cases). Seventeen of the 190 patients had multiple canal involvement. Twelve of the 190 patients demonstrated up-beating vertical nystagmus during the seated–supine positional test. All patients with vertical nystagmus during the test had normal MRI scans.
Demographic data for the 12 patients with up-beating vertical nystagmus are presented in Table I. Of these 12 patients, 7 had true multiple canal involvement (7 out of 190, 3.7 per cent). Five patients had pseudo-bilateral posterior canal BPPV as shown by the asymmetric severity of the nystagmus during the seated–supine positional test and the absence of reversed nystagmus on the healthy side when the patient rose to a sitting position from lying; four of these patients responded to a single repositioning manoeuvre. Two patients had true bilateral posterior canal BPPV and had to be treated by an Epley manoeuvre on both sides. Two patients had left-sided lateral canal canalolithiasis and posterior canal BPPV, whereas three patients had lateral canal cupulolithiasis and posterior canal BPPV; all five needed several treatment manoeuvre attempts for the relief of symptoms. Trauma was one of the leading aetiologies of BPPV.
Demographic data for up-beating vertical nystagmus patients*
* As revealed during the seated–supine positional test. Pt = patient; no = number; BPPV = benign paroxysmal positional vertigo; PC = posterior canal; F = female; LC = lateral canal; M = male
The findings of the comparative analysis of the BPPV patient groups with different types of canal involvement are presented in Table II. The incidence of multiple canal BPPV was significantly lower than that of other BPPV types (p = 0.029). The duration of symptoms was significantly lower in patients with multiple canal BPPV than in those with other types of canal involvement (p = 0.048). Trauma was the leading aetiological factor in multiple canal BPPV patients (p = 0.012). The average number of therapeutic manoeuvres required for the relief of symptoms was statistically significantly higher in patients with multiple canal involvement compared with the other groups (p = 0.041).
Comparative analysis of BPPV patient groups*
* Patients with different types of canal involvement. †The incidence of multiple canal benign paroxysmal positional vertigo (BPPV) was significantly lower than that of other BPPV types in terms of frequency. ‡Statistically significant result. **The duration of symptoms was significantly lower for patients with multiple canal BPPV than for those with other canal involvement; trauma was the leading aetiological factor in those patients. §The average number of therapeutic manoeuvres required for the relief of symptoms was significantly higher for patients with multiple canal involvement compared with the other groups. PC = posterior canal; LC = lateral canal; SC = superior canal
Discussion
Vertical nystagmus during the seated–supine positional test is a rare and interesting condition, and could be a sign of multiple canal involvement. This type of nystagmus, which occurs while the patient is lying down, is most probably the result of stimulation of the semicircular canals on both sides. However, as seen in our five cases with pseudo-bilateral posterior canal BPPV, it is not necessarily due to the presence of otoconia in the posterior canals on both sides.
Care should be taken not to misdiagnose unilateral pseudo cases as true bilateral posterior canal BPPV. Steddin and Brandt were the first to introduce such a possibility.Reference Steddin and Brandt9 They have proposed an inhibitory nystagmus on the non-otoconial side caused by movement of otoconia towards the cupula on the otoconial side, simulating cupulolithiasis of the affected ear. Interestingly, in our five cases of pseudo-bilateral posterior canal BPPV, there was asymmetry in the severity of nystagmus in the straight head-hanging position and a reversal of nystagmus on the affected side when the patient rose to the sitting position. Nystagmus was so mild in the contralateral ear that it was difficult to justify the reversal pattern during sitting. Another interesting point was the complete relief of symptoms in almost all pseudo-bilateral posterior canal BPPV patients after one single Epley manoeuvre on the affected side. Balatsouras et al. have also proposed considering the type of up-beating vertical nystagmus in the straight head-hanging position, to differentiate between the pseudo and true posterior canal BPPV. This nystagmus is purely vertical because of the cancellation of the torsional component associated with the bilaterality of the otoconial movement, and it is slightly torsional in unilateral cases.Reference Balatsouras, Koukoutsis, Ganelis, Korres and Kaberos6 On the other hand, what we observed in our two true bilateral posterior canal BPPV cases was that the severity of nystagmus was very similar on both sides. This made the treatment more difficult as several attempts at repositioning manoeuvres failed to provide complete relief.
• In lateral canal benign paroxysmal positional vertigo (BPPV), horizontal nystagmus observed when patient is lying down aids understanding of affected side
• Horizontal nystagmus beats towards healthy side in canalolithiasis and towards affected side in cupulolithiasis
• The presence of positional vertical up-beating nystagmus in patients with BPPV while lying down is rarely seen and is a unique peripheral sign
• This sign may be indicative of multiple canal involvement or bilateral stimulation of posterior canals in the case of unilateral (pseudo-bilateral) posterior canal BPPV
• The seated–supine positional test, combined with roll-on and head-hanging tests, help provide a true diagnosis
• In this study, the average number of therapeutic manoeuvres required for relief of symptoms was significantly higher in patients with multiple canal involvement
Bilateral or multi-canal involvement in patients with BPPV is rare.Reference Katsarkas10 Tomaz et al. reported 1.5 per cent multiple canal involvement and stated that trauma was the main risk factor.Reference Tomaz, Gananca, Gananca, Gananca, Caovilla and Harker11 In our series, multiple canal involvement affected about 3.7 per cent of the patients and the majority of those had trauma aetiology. Pollak et al. reviewed 28 patients with bilaterally positive Dix–Hallpike test findings. Of those patients, 12 were diagnosed with pseudo-bilateral BPPV and they did not differ from patients with unilateral posterior canal BPPV in terms of clinical characteristics. However, trauma was a more common trigger than other known causes of BPPV.Reference Pollak, Stryjer, Kushnir and Flechter12 Tomaz et al. reported that more than 90 per cent of patients with multiple canal involvement had simultaneous involvement of the lateral and posterior canals on the same or on opposite sides, and all were canalolithiasis cases.Reference Tomaz, Gananca, Gananca, Gananca, Caovilla and Harker11 Lateral and posterior canal BPPV, either on the same or on the contralateral side, is the most common type of mixed canal BPPV.Reference Imai, Takeda, Ito, Nakamae, Sakae and Fujioka13, Reference Bertholon, Chelikh, Tringali, Timoshenko and Martin14 We also observed the simultaneous occurrence of lateral and posterior canal BPPV. However, three of the patients with lateral canal involvement were cupulolithiasis cases.
Administration of the straight head-hanging positional test on patients with BPPV at the very beginning of the test battery is important and can alert one to the presence of multiple canal involvement; although the condition is rare, clear diagnosis of affected patients is akin to mathematical problem solving. Patients should also be informed that treatment is challenging; multiple involvement of the semicircular canals is one of the most important variables affecting treatment outcome.Reference Macias, Lambert, Massingale, Ellensohn and Fritz15 The number of therapeutic manoeuvres applied in this series was much higher in patients with multiple canal involvement than in patients with unilateral posterior or lateral canal BPPV, whether canalolithiasis or cupulolithiasis.
In conclusion, in patients with BPPV, the presence of vertical up-beating nystagmus while lying down is a unique peripheral sign and may help with the true diagnosis in several ways. Therefore, the seated–supine positional test should always be included in the test battery. In particular, patients with a poor response to repositioning procedures should be reviewed with this test.
