Herpesviruses, polyomaviruses, parvoviruses, papillomaviruses, and anelloviruses in vestibular schwannoma.

Etiology of vestibular schwannoma (VS) is unknown. Viruses can infect and reside in neural tissues for decades, and new viruses with unknown tumorigenic potential have been discovered. The presence of herpesvirus, polyomavirus, parvovirus, and anellovirus DNA was analyzed by quantitative PCR in 46 formalin-fixed paraffin-embedded VS samples. Five samples were analyzed by targeted next-generation sequencing. Viral DNA was detected altogether in 24/46 (52%) tumor samples, mostly representing anelloviruses (46%). Our findings show frequent persistence of anelloviruses, considered normal virome, in VS. None of the other viruses showed an extensive presence, thereby suggesting insignificant role in VS.

Inner ear barotrauma and inner ear decompression sickness: a systematic review on differential diagnostics.

INTRODUCTION: Inner ear barotrauma (IEBt) and inner ear decompression sickness (IEDCS) are the two dysbaric inner ear injuries associated with diving. Both conditions manifest as cochleovestibular symptoms, causing difficulties in differential diagnosis and possibly delaying (or leading to inappropriate) treatment. METHODS: This was a systematic review of IEBt and IEDCS cases aiming to define diving and clinical variables that help differentiate these conditions. The search strategy consisted of a preliminary search, followed by a systematic search covering three databases (PubMed, Medline, Scopus). Studies were included when published in English and adequately reporting one or more IEBt or IEDCS patients in diving. Concerns regarding missing and duplicate data were minimised by contacting original authors when necessary. RESULTS: In total, 25 studies with IEBt patients (n = 183) and 18 studies with IEDCS patients (n = 397) were included. Variables most useful in differentiating between IEBt and IEDCS were dive type (free diving versus scuba diving), dive gas (compressed air versus mixed gas), dive profile (mean depth 13 versus 43 metres of seawater), symptom onset (when descending versus when ascending or surfacing), distribution of cochleovestibular symptoms (vestibular versus cochlear) and absence or presence of other DCS symptoms. Symptoms of difficult middle ear equalisation or findings consistent with middle ear barotrauma could not be reliably assessed in this context, being insufficiently reported in the IEDCS literature. CONCLUSIONS: There are multiple useful variables to help distinguish IEBt from IEDCS. Symptoms of difficult middle ear equalisation or findings consistent with middle ear barotrauma require further study as means of distinguishing IEBt and IEDCS.

Inner ear decompression sickness in Finland: a retrospective 20-year multicenter study.

Introduction: Inner ear decompression sickness (IEDCS) is a condition from which only a minority of patients recover completely, the majority ending up with mild to moderate residual symptoms. IEDCS has been reported after deep technical dives using mixed breathing gases, and moderate recreational dives with compressed air as the breathing gas. Considering this and the high proportion of technical diving in Finland, a comparison between IEDCS cases resulting from technical and recreational dives is warranted. Methods: This is a retrospective examination of IEDCS patients treated at Hyperbaric Center Medioxygen or National Hyperbaric Centre of Turku University Hospital from 1999 to 2018. Patients were included if presenting with hearing loss, tinnitus, or vertigo and excluded if presenting only with symptoms of middle ear or cerebellar involvement. Patients were divided into technical and recreational divers, based on incident dive. Results: A total of 89 (15.6%) of all DCS patients presented with IEDCS, two-thirds treated during the latter decade. The most common predisposing factors were consecutive days of diving (47.2%), multiple dives per day (53.9%), and factors related to an increase in intrathoracic pressure (27.0%). The symptoms were cochlear in 19.1% and vestibular in 93.3% of cases, symptoms being more common and severe in technical divers. Complete recovery was achieved in 64.5% of technical and 71.4% of recreational divers. Conclusion: The incidence of IEDCS in Finland is increasing, most likely due to changing diving practices. A comprehensive examination should be carried out after an incident of IEDCS in all cases, irrespective of clinical recovery.

Simultaneous bilateral stapes surgery after follow-up of 13 years.

BACKGROUND: Eighteen patients underwent simultaneous bilateral stapes surgery in 2003-2006. OBJECTIVES: We evaluated the long-term outcomes in this patient group, and assessed their hearing in noise and binaural hearing. MATERIAL AND METHODS: Fifteen patients returned questionnaires concerning their hearing, taste function, and balance. Thirteen patients underwent pure-tone and speech audiogram, Finnish matrix sentence test, video head impulse test, and clinical examination on average 13 years after surgery. RESULTS: We found no significant difference in air- and bone conduction pure-tone average, speech audiometry, and the air-bone gap between the 1-year and the late postoperative visits. One patient had bilaterally a partial loss of the vestibulo-ocular reflex of unknown cause. CONCLUSIONS AND SIGNIFICANCE: The hearing results 13 years after simultaneous bilateral stapes surgery remained good without any significant delayed complications. Simultaneous bilateral stapes surgery is a viable treatment option in selected patients with otosclerosis.

Bilateral Vestibular Hypofunction in Quantitative Head Impulse Test: Clinical Characteristics in 23 Patients.

OBJECTIVE: To explore clinical features of patients with bilateral vestibular hypofunction (BVH) verified in motorized head impulse test (MHIT). MATERIALS AND METHODS: We examined clinical records of 23 adult patients (10 males and 13 females), whose gain of the vestibulo-ocular reflex in the MHIT was bilaterally lowered. Fifteen of 62 unilateral cochlear implant (CI) recipients routinely tested both pre- and postoperatively with the MHIT had BVH. Eight of 198 vestibular outpatients selected to the MHIT due to clinical causes had BVH. Clinical characteristics and a questionnaire regarding current sensations were analyzed. RESULTS: The mean gain±SD in the MHIT was 0.26±0.17 on the right and 0.26±0.14 on the left side. The mean gain in the CI recipients did not differ from that of vestibular outpatients (p>0.05). All outpatients with BVH suffered from oscillopsia, whereas only 46% of CI recipients experienced oscillopsia (p=0.048). Instability was more prominent (p=0.004) and quality of life further decreased (p=0.012) among vestibular outpatients compared with CI patients. Most common etiology for the BVH was meningitis. Other causes were either sudden or progressive loss of labyrinthine function, bilateral Meniére's disease, and ototoxicity. CONCLUSION: BVH is rare even in a specialized clinic. Vestibular outpatients were more disabled than CI recipients with the BVH.

Two-dimensional signal analysis reduced from three-dimensional nystagmus eye movements.

Earlier we developed signal analysis for nystagmus measured from otoneurological patients suffering from vertigo and dizziness. It was based on three rotation directions of the eye: horizontal, vertical and torsional. However, nystagmus frequently appears only in two of the former directions. In order to enable two-dimensional analysis approach on the basis of various pairs from the original three, we designed and implemented an advanced method from our earlier one. These signals can be used to investigate and model the dysfunction of semicircular canals in the inner ear. Nystagmus has to be stimulated for healthy subjects, but in patients it can also be spontaneous. The method developed was tested with the signals of 30 otoneurological patients.

Head tilt is pronounced after an ipsilateral head roll in patients with vestibular schwannoma.

The study aimed to measure utricular function by directly quantifying head tilt in vestibular schwannoma (VS) patients using regular video-oculography (VOG) equipment with integrated head-position sensor, and to correlate the results with patients' symptoms and signs. We recorded head tilting after exclusion of visual cues (static head tilt), and after returning to the centre following lateral head rolls towards each side [subjective head vertical (SHV)]. Head tilt in 43 patients was measured preoperatively and approximately 4 months postoperatively, and compared to that of 20 healthy subjects. Symptoms were assessed with a structured questionnaire. Static head tilt in patients was significantly greater than in controls (1.0° ± 0.9°) preoperatively (1.6° ± 1.5°, p = 0.04) and postoperatively (1.7° ± 1.5°, p = 0.01). Mean SHV in patients was significantly greater than in controls (1.2° ± 1.0°) preoperatively (2.0° ± 1.9°, p = 0.03) and postoperatively (2.5° ± 1.8°, p = 0.001), increasing non-significantly after surgery (p = 0.3). Side-specific SHV after ipsilateral head rolls was significantly greater than after contralateral head rolls preoperatively (2.8° ± 3.3° vs. -0.5° ± 3.0°, p = 0.001) and postoperatively (3.3° ± 3.0° vs. 0.6° ± 3.2°, p < 0.001). The intensity of dizziness increased postoperatively (p = 0.04), but its effect on quality of life remained unchanged. In conclusion, commercial VOG equipment including a head-position sensor allows direct evaluation of head tilt in VS patients. The slight head tilt towards the ipsilateral side becomes most evident after returning from an ipsilateral head roll.

[Nystagmus]. / Nystagmus.

Physiological nystagmus stabilizes gaze during head movements and pathological nystagmus reflects a disorder of the vestibulo-ocular reflex (VOR). Pathological nystagmus appears or strengthens usually during change in head position. Therefore, dizziness or nystagmus associated with head movements is not specific to benign paroxysmal positional vertigo unless it is verified in specific positional test. Peripheral nystagmus decelerates during visual fixation, accelerates when gaze is turned towards the fast phase, does not change direction, and is usually composed of several directional components unlike central nystagmus. The velocity and frequency of the slow phase of nystagmus can be measured with electronystagmography or video-oculography.

Immediate postoperative nystagmus and vestibular symptoms after stapes surgery.

CONCLUSION: Vestibular disturbance is frequent, but mild even immediately after stapes surgery. Vestibular symptoms improved or disappeared quickly, and they did not correlate with nystagmus. Outpatient stapes surgery performed under local anaesthesia is a feasible approach. OBJECTIVE: Vestibular symptoms are common and may prevent outpatient surgery. The time course of vestibular disturbance is unclear, and we aimed to evaluate it immediately after the operation in the recovery room. METHODS: Twenty patients with otosclerosis undergoing stapedotomy were prospectively included in the study. Postoperative symptoms were collected and nystagmus was recorded with video-oculography (VOG) on average 29 min after the surgery. RESULTS: None of the patients had spontaneous nystagmus with gaze fixation. Nine patients (45%) had slow spontaneous horizontal nystagmus (mean slow phase velocity of 1.1°/s) in the primary position without gaze fixation. In seven of these, the nystagmus obeyed Alexander's law. Nine patients (45%) had vestibular symptoms at the end of the surgery, and four patients at the time of VOG recording. Vertigo was experienced immediately after the operation in five, floating sensation in two, and unspecific dizziness in two patients. Vestibular symptoms were mild or moderate in most patients. The occurrence of nystagmus did not correlate with vestibular symptoms (p > 0.05).

Cochlear implantation rarely alters horizontal vestibulo-ocular reflex in motorized head impulse test.

OBJECTIVE: Determine the change in vestibular function in patients receiving a unilateral cochlear implant, and to compare these results with other signs and symptoms. STUDY DESIGN: Prospective cohort study. SETTING: Academic tertiary referral center. PATIENTS: Forty-four adults (mean age, 55 yr; range, 30-76 yr) receiving their first cochlear implant. INTERVENTION: Cochlear implantation. MAIN OUTCOME MEASURES: Horizontal high-frequency vestibulo-ocular reflex (VOR) was measured using the motorized head impulse rotator preoperatively and twice (on average two and 19 months) postoperatively. VOR gain and asymmetry were calculated (mean ± standard deviation). Symptoms were assessed with a structured questionnaire. RESULTS: Gain on the operated side was 0.77 ± 0.26 preoperatively, 0.75 ± 0.30 in the early and 0.73 ± 0.33 in the late postoperative control, and did not change significantly. Mean asymmetry remained within 9% to 10% in all test occasions. Dizziness symptom score or dizziness-related quality of life score did not change significantly. General quality-of-life score improved significantly from that of preoperative 3.5 ± 1.2 to that of 2.6 ± 1.1 postoperatively (p = 0.01). Subjective hearing scores improved significantly from 4.9 ± 0.3 to 2.4 ± 1.0, respectively (p = 0.0000). Gain was decreased significantly in 4 patients (10%) in the early and in 2 patients (7%) in the late postoperative control. CONCLUSION: Late high-frequency loss of vestibular function or vestibular symptoms is rare but possible after cochlear implantation surgery. This should be taken into account in patient counseling especially when considering bilateral cochlear implant surgery.

Recovery of the horizontal vestibulo-ocular reflex in motorized head impulse test is common after vestibular loss.

CONCLUSION: Decreased horizontal vestibulo-ocular reflex (VOR) gain measured with the motorized head impulse rotator usually recovers at least partially within a few months after sudden unilateral vestibular loss. In addition to traditional evaluation of nystagmus, head impulse test responses provide valuable information on the severity and recovery of vestibular loss. OBJECTIVES: To quantify recovery of vestibular function with the motorized head impulse test in patients with acute unilateral peripheral vestibular loss, and to compare these results with other signs and symptoms. METHODS: We recorded prospectively the horizontal VOR with the motorized head impulse rotator in 30 patients with sudden unilateral vestibular deficit on average 3 days after the onset (early). Twenty patients were measured sequentially on average 3 months later (late). We calculated VOR gain and asymmetry (mean ± standard deviation). RESULTS: The early ipsilesional gain of 0.49 ± 0.21 improved highly significantly to the late gain of 0.79 ± 0.23 (p = 0.0000). The respective asymmetry improved highly significantly from 32 ± 18% to 12 ± 14% (p = 0.0002). Gain or asymmetry recovered at least partially in 80% of the patients. The late high symptom score correlated with low gain (p = 0.043) and high asymmetry (p = 0.018).

Suppression of spontaneous nystagmus during different visual fixation conditions.

Analysis of spontaneous nystagmus is important in the evaluation of dizzy patients. The aim was to measure how different visual conditions affect the properties of nystagmus using three-dimensional video-oculography (VOG). We compared prevalence, frequency and slow phase velocity (SPV) of the spontaneous nystagmus with gaze fixation allowed, with Frenzel's glasses, and in total darkness. Twenty-five patients (35 measurements) with the peripheral vestibular pathologies were included. The prevalence of nystagmus with the gaze fixation was 40%, and it increased significantly to 66% with Frenzel's glasses and regular room lights on (p < 0.01). The prevalence increased significantly to 83% when the regular room lights were switched off (p = 0.014), and further to 100% in total darkness (p = 0.025). The mean SPV of nystagmus with visual fixation allowed was 1.0°/s. It increased to 2.4°/s with Frenzel's glasses and room lights on, and additionally to 3.1°/s, when the regular room lights were switched off. The mean SPV in total darkness was 6.9°/s. The difference was highly significant between all test conditions (p < 0.01). The frequency of nystagmus was 0.7 beats/s with gaze fixation, 0.8 beats/s in both the test conditions with Frenzel's glasses on, and 1.2 beats/s in total darkness. The frequency in total darkness was significantly higher (p < 0.05) than with Frenzel's glasses, and more so than with visual fixation (p = 0.003). The VOG in total darkness is superior in detecting nystagmus, since Frenzel's glasses allow visual suppression to happen, and this effect is reinforced with gaze fixation allowed. Strict control of visual surroundings is essential in interpreting peripheral nystagmus.

Subjective head vertical test reveals subtle head tilt in unilateral peripheral vestibular loss.

Utricular dysfunction has been indirectly measured with subjective visual horizontal or vertical testing. Video-oculography equipment with integrated head position sensor allows direct evaluation of head tilt. The aim was to assess head tilt after peripheral vestibular lesion by recording tilting of the head after excluding visual cues (static test condition), and after three lateral head tilts to both sides [subjective head vertical (SHV)]. Thirty patients with unilateral, peripheral vestibular loss were measured in the acute state, and 3 months later. Twenty healthy, age- and sex-matched subjects served as controls. Mean static tilt of 2.6 ± 1.1° in patients with acute vestibular loss differed significantly from that of 1.0 ± 0.4° in healthy subjects (p = 0.004), and from that of 1.1 ± 0.5° during the follow-up visit (p = 0.008). The mean SHV of 3.4 ± 0.7° in patients with acute vestibular loss was significantly more than that of 1.2 ± 0.5° in controls (p < 0.001). The SHV towards the lesion was 4.9 ± 1.0° while returning from the lesion side and 2.0 ± 1.0° while returning from the healthy side. The SHV was definitely abnormal in 60%, moderately abnormal in 20% and normal in 20% of the patients in acute state. Abnormal SHV persisted in only 20% of the patients indicating that recovery of the peripheral utricular function is occurring within months. In summary, head tilts slightly towards acute peripheral lesion, and this tilting is reinforced, when the head is actively moved on the lesion side.

Signal analysis of three-dimensional nystagmus for otoneurological investigations.

Three-dimensional signal analysis can be applied to eye movements called nystagmus in order to study otoneurological patients suffering from vertigo and other balance problems. We developed an analysis and modeling algorithm for three-dimensional nystagmus measured by a video-oculography system. We were also interested in verifying an otoneurological hands-on convention called Ewald's first law in a strict physiological sense in vestibular patients. We recorded nystagmus from 42 patients all suffering from vertigo or dizziness. The underlying pathology was unilateral in 39 patients, bilateral in one patient, and central in two patients. Video-oculography was used to record three-dimensional nystagmus to separately produce horizontal, vertical, and torsional signals for each eye. On the basis of signal analysis techniques and straightforward vector calculus, we were able to recognize slow phases of nystagmus to compute their angular velocities to estimate from which part of the inner ear the disorder originated. We found that for all 42 patients the plane of one of the two horizontal semicircular canals was the closest. We were able to quantitatively estimate the influence of different semicircular canals, and, despite the pathology, horizontal canals seemed to be predominant in driving the nystagmus. The signal analysis and modeling algorithm developed is effective in studying otoneurological problems registered with nystagmus and opens new insights in three-dimensional nystagmography. Our results strongly support Ewald's first law.

Disruption of the head direction cell signal after occlusion of the semicircular canals in the freely moving chinchilla.

Head direction (HD) cells in the rat anterodorsal thalamic nucleus (ADN) fire relative to the animal's directional heading. Lesions of the entire vestibular labyrinth have been shown to severely alter VIIIth nerve input and disrupt these HD signals. To assess the specific contributions of the semicircular canals without altering tonic VIIIth nerve input, ADN cells were recorded from chinchillas after bilateral semicircular canal occlusion. Although ADN HD cells (and also hippocampal place cells and theta cells) were identified in intact chinchillas, no direction-specific activity was seen after canal occlusions. Instead, "bursty" cells were observed that exhibited burst-firing patterns similar to normal HD cells but with firing unrelated to the animal's actual head direction. Importantly, when pairs of bursty cells were recorded, the temporal order of their firing was dependent on the animal's turning direction, as is the case for pairs of normal HD cells. These results suggest that bursty cells are actually disrupted HD cells. The present findings further suggest that the HD cell network is still able to generate spiking activity after canal occlusions, but the semicircular canal input is critical for updating the network activity in register with changes in the animal's HD.

Simultaneous bilateral stapes surgery.

CONCLUSIONS: The patients recovered from the surgery as after unilateral surgery. The success rate for hearing improvement was good both subjectively and objectively, and this was also displayed in the quality of life. According to our study, simultaneous bilateral stapes surgery can be performed safely in selected patients with bilateral conductive hearing loss. OBJECTIVES: Otosclerosis is bilateral in the majority of patients. In this study we evaluated the outcome of simultaneous bilateral stapes surgery. SUBJECTS AND METHODS: Eighteen patients suffering from bilateral otosclerosis or osteogenesis imperfecta were prospectively included. After operation, hearing and vestibular function were followed by audiometry and visual feedback posturography (VFP). Patients estimated their hearing gain, the intensity of vestibular symptoms and quality of life score with a questionnaire during the follow-up period of 1 year. RESULTS: The mean improvement in pure-tone average (PTA) air conduction (PTA-AC) was 18 dB (range 1-41 dB). The mean air-bone gap (AB-GAP) diminished from 22 dB (range 10-41 dB) to 7 dB on both sides (range 0-18 dB). The mean preoperative score of 2.3 for hearing improved significantly to 4.1 (p<0.001). Vestibular symptoms were mild and temporary. The VFP was not permanently impaired in any of the patients. The quality of life score improved significantly from 3.4 to 1.3 postoperatively (p<0.001).

Postural control after vestibular schwannoma resection measured with visual feedback posturography.

BACKGROUND: Vestibular symptoms after surgery diminish rapidly, but the simultaneous progress in active postural control has not been fully addressed. OBJECTIVES: The aim was to evaluate the progress in postural control in operated vestibular schwannoma (VS) patients with visual feedback posturography (VFP). METHODS: 36 consecutive patients with unilateral VS were studied with the VFP pre-operatively, 1 month and 3 months after the surgery. The accuracy and velocity of active postural control movements to distant targets in VFP was measured and compared to that of healthy controls. RESULTS: The hold percentage within the targets was significantly reduced in the VS patients compared to the controls (pre-operatively p = 0.005; postoperatively at 1 month p = 0.002 and at 3 months p = 0.017). The sway velocity (SV) within the targets among patients with VS was significantly increased pre-operatively (p = 0.009), at the 1-month (p = 0.004) and at the 3-month follow-up visits (p = 0.016). All the postural control parameters except SV tended to improve slightly postoperatively. The consecutive VFP measurements in individual VS patients correlated statistically significantly (p < 0.001 for all parameters). The abnormality in the pre-operative VFP results correlated statistically significantly with that of postoperative VFP (p = 0.001). CONCLUSIONS: The VFP is an objective and repeatable method, which can be used to assess and follow up the active postural control in individual patients with VS. Persisting abnormality in the VFP seems to be an indication for more aggressive vestibular rehabilitation to normalize the disturbed postural control.

Video-oculography findings in patients with otosclerosis.

OBJECTIVE: To evaluate the existence of vestibular irritation with video-oculography before and after stapes surgery and to examine whether there would be signs of specific end-organ irritation. STUDY DESIGN: A prospective study of preoperative and postoperative nystagmus, vertigo, and hearing thresholds. SETTING: University hospital, tertiary referral center. PATIENTS: Thirty-three patients (mean age, 47 yr) with otosclerosis. INTERVENTION: Stapedotomy/stapedectomy with laser or microdrill. MAIN OUTCOME MEASURES: Spontaneous, gaze-evoked, and head-shaking nystagmus was measured preoperatively and approximately 1 week, 1 month, and 3 months after the operation. Three dimensions of nystagmus were identified and their slow-phase velocities were calculated. RESULTS: Spontaneous horizontal nystagmus was found preoperatively in 18% (slow-phase velocities, 1.3-3.3 deg/s) and postoperatively in 11 to 19% of the patients (slow-phase velocities, 1.3-3.8 deg/s). Head-shaking nystagmus was not detected preoperatively. After the operation, 11 to 15% of the patients had head-shaking nystagmus (slow-phase velocities, 6.6-17.8 deg/s), but this prevalence did not differ statistically significantly from the preoperative level (p = 0.18). Vertical nystagmus was found equally pre- and postoperatively. Torsional nystagmus was not found. One week after the operation, nine patients (27%) had some sensation of vertigo, but it lasted over 1 month in only one patient. We found no significant correlation with vertigo and the types of nystagmus. CONCLUSION: Nystagmus with a low slow-phase velocity can occur in patients with otosclerosis. However, according to the video-oculographic findings and subjective symptoms, significant vestibular dysfunction seems to be rare and temporary after stapes surgery.