1 Assistant Professor, State University of Rio de Janeiro (UERJ)
2 Joint Professor, Federal University Fluminense (UFF)
3 Joint Professor Federal University of Rio de Janeiro (UFRJ)

Federal University of Rio de Janeiro(UFRJ)

Address correspondence to: Aída Regina Monteiro de Assunção - Rua Mem de Sá 186, Icaraí, Niterói, RJ - 24220-261 - Tel/fax (55 21) 7104278 - e-mail: aidaregina@openlink.com.br

Master dissertation submitted to Federal University of Rio de Janeiro, Master in Otorhinolaryngology, December 2000.

Awarded paper - area of otology, presented on 26/08/01 at II Congresso Triológico de Otorrinolaringologia, Goiânia - GO.

Article submitted on December 18, 2001. Article accepted on October 15, 2001.

INTRODUCTION

Active cephalic auto-rotation, also called vestibular auto-rotation or active cephalic balance, is a quick non-invasive, easy to perform test that causes no discomfort to patients, can be easily performed in children and assesses vestibulo-ocular reflex (VOR) in the physiological frequencies of head rotation used in daily life (1 to 4kHz)9, 5, 13.

Traditional tests to assess VOR, such as caloric test and rotation chair, used together with electronystagmography (ENG), vectoelectronystagmography (VENG) or computed electronystagmography, employ low frequencies of stimulation (between 0.003 and 3kHz)17, 9, which are quite different from physiological frequencies and they use stimuli that are obtained through non-natural conditions (irrigation of the external auditory canal with water or air, or body rotation), generating a great percentage of normal results in patients with vestibular dysfunction2, 16.

High prevalence of complaints of body balance disorders associated to normal results in the vestibular tests applied in the otoneurological routine justifies that investigation of more precise complementary tests in order to clearly define the severity of the impairment and the participation of the labyrinth in the genesis of dizziness.

The objective of VOR is to stabilize the retina image and to keep clear vision and body balance during walking and habitual head movements. Thus, ocular movements should be similar and opposed to head movements. Abnormal responses of VOR generate body balance disorders that are the second most frequent complaint in ENT, general practitioner and neurologist practices in patients below 65 years and the most frequent one in patients over 65 years of age. About 65% of the elderly patients up to 70 years and 75% over that age present symptoms of balance disorders21.

Body balance is maintained as a result of interaction of the different systems (vestibular, visual, proprioceptive), under the coordination of the cerebellum. Information provided by these systems should be coherent. When there is conflicting information, the result is body balance disorder6.

The most frequent complaints related to body balance are dizziness and vertigo. Dizziness is the sensation of body balance change with non-rotation characteristic. Vertigo is rotation dizziness, when the patient feels as if his body or the objects around it are spinning round10.

The objective of the present paper was to assess patients with dizziness and vertigo using the horizontal active cephalic auto-rotation test with fixed target, comparing the symptoms with the alterations found.

Material and method

We assessed the medical charts of all patients submitted to horizontal active cephalic auto-rotation test with fixed target in the period between January 1998 and December 1999 at Clínica Otorrinos Reunidos Ltda., amounting to 1,902 patients. We collected age, gender, main complaint, result of audiometric test, frequency range of cephalic movement, abnormalities detected at the horizontal active cephalic auto-rotation test and symptoms during the test. We included in the study patients who had complaints of dizziness (non-rotation complaints) or vertigo (rotation complaints), amounting to 1,281 tests. We excluded 621 patients who presented other complaints of tinnitus and hypoacusis.

It was a retrospective study, guaranteeing data confidentiality and non-identification of patients. It was approved by the Ethics Committee on Research of Hospital Clementino Fraga Filho, Federal University of Rio de Janeiro on June 10, 1999, under protocol number 53/99-CEP.

We used the devices VORTEQ (Vestibular Ocular Reflex Test Equipment) manufactured by MICRO MEDICAL TECHNOLOGIES, an integral part of the Computed Nystagmography System META 4 CHANNEL ULTRA COMPUTERIZED ENG Version 4.5, installed in the computer COMPAQ DESKPRO PENTIUM II, coupled to a printer HP (HEWLETT PACKARD) LASER JET 6L.

The horizontal active cephalic auto-rotation test with fixed target was performed with the patient comfortably seated in a semi-dark environment. The skin was previously cleaned with gauze soaked in alcohol to remove impurities and place the electrodes (two active electrodes, one on the right external peri-orbital point and another on the left, plus a neutral electrode placed on the frontal midline). The sensor of angular speed, on the vertical position, was firmly adjusted to the head of the patient, who was asked to maintain the eyes opened, observing a fixed light point 100cm across from him, and to move the head to the right and left, with an amplitude of angular rotation of approximately 10o, following the acoustic signal of varied frequency generated by an electronic metronome coupled to the equipment.

The first stimulation was performed in frequency of 1Hz, then it started from 1Hz to 3Hz and the last stimulation was from 1Hz to 5Hz, each sequence lasting 15 seconds, and cephalic movement of patients could reach up to 7.5Hz. The computer selected the head rotation cycles during the test that were grouped according to frequency. All cycles close to 1Hz (from 0.5 to 1.5Hz) were placed in a group, those close to 2Hz were placed in another, and so on8, 2, 4, 13. The patient was trained before we started recording of the test. Frequency ranges of the test were determined by head movement of the patient and the computed program enabled analysis of frequencies in the range of 0.5 to 7.5Hz.

The normal range used as reference was provided by the equipment, and results were easily visualized by means of graphs plotted on the monitor screen, where the area between the two continuous lines on the graph represented the normal limits. The upper line represented the mean plus two standard deviations and the lower line represented the mean minus two standard deviations8, 2, 13.

The VOR parameters assessed in the active cephalic auto-rotation test were: gain, defined as the relation between eye and head speed (relation between stimulus intensity and response); phase, analyzed as the relation between delay and advance in ocular response in relation to head movement (angular relation between the stimulus and the response curve), and symmetry, comparison between gains of cephalic movement of opposite directions13, 14.

The test is painless and poses no risks. The patient may experience dizziness, nausea and headache, and that is why they were instructed to fast for 4 hours before the test, interrupt medication use (anxiolytic, tranquilizer, hypnotic, analgesic, and labyrinth depressor) for 72 hours before the test and food intake (coffee, tea, chocolate, alcoholic drinks, soft drinks) and smoking 24 hours before the test, so that they would not interfere in the labyrinth responses. If patients were using anticonvulsive drugs, they were instructed to ask the neurologist about the possibility of interrupting them. Tests were performed in off-seizure periods.

In order to measure the correlation between variables of the sample, we used the non-parametric contingency coefficient (C) and applied the significance test X2 (chi-square), adopting the significance level of 0.05 (p<0.005), being 95% of certainty of positive or negative results derived from the study.

Age ranges were distributed in intervals, presenting data in a continuous form, without overlapping, so that each value observed could be allocated to one and only one interval, according to Sturges formula, which enabled a more uniform distribution of the number of subjects in each interval.

RESULTS

Characteristics of the sample

We analyzed 1,281 medical charts of patients who had complaints of dizziness and vertigo who were submitted to horizontal active cephalic auto-rotation test with fixed target between January 1998 and December 1999.

Age of patients ranged from 3 to 93 years, mean of 49.6 years, standard deviation (SD) 16.8, distributed according to Table 1.

Characteristics of symptoms reported by patients in the anamnesis

Vertigo was the most frequent complaint (60.9%) (896), whereas dizziness was reported by 30.1% (385) (Table 3).

Results of horizontal active cephalic auto-rotation test with fixed target

The frequency range of responses to horizontal active cephalic auto-rotation test ranged from 1.5 to 7.5Hz, mean of 3.5Hz, SD 1.2 (Table 4).

Correlation between abnormalities in the horizontal active cephalic auto-rotation test with fixed target and complaint of dizziness/vertigo

Upon crossing the data concerning abnormalities in the active cephalic auto-rotation test in patients with dizziness and vertigo complaints (Table 9), we noticed that the percentage of patients with complaint of vertigo and normal active cephalic auto-rotation (659 patients - 73.55%) was similar to that of patients with complaint of dizziness and normal active cephalic auto-rotation test (278 patients - 72.20%). The same proportion was observed for the comparison of complaint and abnormal result in the active cephalic auto-rotation - 26.45% for patients with vertigo and 27.80% for patients with dizziness and abnormal results.

Significance test did not allow rejection of nullity, indicating that any differences could be considered as expected casual variations from a random sample of population, which did not represent relation among the variables of the population from where the sample was selected. It was observed that the contingency coefficient was very low, indicating correlation close to zero (C=0.01).













Correlation between abnormal result in horizontal active cephalic auto-rotation with fixed target and gender.

The proportion of normal and abnormal tests was similar for both male and female subjects (Table 10).

The significance test did not allow rejection of nullity, observed values were very close to the expected values, indicating that differences may be considered as expected casual variations of a random sample of the population, which did not represent relation among the variables of the population from where the sample was selected (C=0.04).

DISCUSSION

Relation between genders

Among 1,281 patients, 946 were females (73.8%) and 335 were males (26.2%) (Table 2), showing that complaints of dizziness and vertigo are more common among female subjects. The data are in accordance with those found in the studied literature.

Caovilla et al.7 and Ganança et al.12 referred that dizziness is more frequent in female subjects at a proportion of 2:1.

Maudonnet et al.22, assessed 4,825 patients and found 3,124 (64.75%) female and 1,702 (35.25) male subjects.

Caovilla(3), in a study with 1,000 patients, found 625 cases of female subjects and 375 of male subjects.

Ganança(15), in a survey of 7,850 consecutive cases of vertigo and other types of dizziness, assessed in the period between January 1985 and June 2000, found 4,812 (61.3%) female and 3,038 (38.7%) male cases.

Relation between age ranges

In our sample, the age range varied from 3 to 93 years, and the highest incidence was between 38 and 46 years (19%) (Table 1), data similar to those collected by other authors.

Caovilla et al.7, in patients aged between 5 months and 81 years reported that dizziness were not very frequent from 5 to 20 years of age (6.2%), affecting preferably patients in the age range of 21 to 80 years (32.3% between 21 and 40 years; 34.7% between 41 and 60 years; 24.6% between 61 and 80 years). The prevalence in patients older than 81 years (2.2%) was minimized because of the reduced number of patients in the age range.

Maudonnet et al.22, assessed 4,825 patients with cochleo- vestibular diseases and found that the highest percentage of affections was in the age range 40 to 50 years, 1,252 patients (25.9%) were in the age range from 30 to 40 years and the percentage was 22.16%, decreasing to 18.07% in the age range of 50 to 60 years.

Caovilla3 found the age range varying from 17 to 84 years in a study with 1,000 patients.

Ganança15 in his survey of 7,850 cases found patients from zero to 95 years. The highest frequency was between ages 31 and 75 years (72.25%), with the highest percentage in the range of 70 to 75 years (9.48%).

DIZZINESS AND VERTIGO

The complaint of vertigo was reported by 896 patients (69.9%) and dizziness by 385 (30.1%) patients (Table 3). Similar results were found by Caovilla et al.7 in a study in which vertigo was more frequent than dizziness (63.7%). Non-rotation dizziness was less frequent in her study (22.1%) and association of both types of dizziness in the same patient amounted to 14.2%.

Bento et al.1, in a study with 230 patients, found instability in 58 patients and rotation dizziness (vertigo) in 60 patients.

FREQUENCY RANGE

The frequency range of responses of the active cephalic auto-rotation test varied from 1.5 to 7.5Hz, mean of 3.5Hz and standard deviation of 1.2 (Table 4).

Fineberg et al.9 assessed 15 patients ranging in age from 19 to 71 years and compared the results of day light testing and dark room testing and did not find significant differences between frequencies of 2 and 6Hz.

O'Leary et al.24 tested elderly subjects without cochlear or vestibular pathologies and young health subjects using active cephalic auto-rotation (VAT) in order to compare the results and to define normal values in patients older than 65 years. Comparing to young subjects, the elderly generally had cephalic movements slower than 4kHz, whereas young people responded at about 6Hz.

Meulenbroeks et al.23, conversely, found a great number of subjects who were not capable of performing cephalic movements above 4Hz.

Active cephalic auto-rotation (VAT)

In the horizontal active cephalic auto-rotation test with fixed target, performed in 1,281 patients, we found 344 abnormal tests (26.9%).

The most frequent alterations were related to gain. Isolated gain increase occurred in 7.2% and other gain-associated alterations were seen in 11.8%, amounting to 241 patients (19%) (Table 6).

Tomlinson et al.28 assessed six healthy young adults under different conditions of target observation, and they did not find any significant gain alteration in high frequencies head rotation in the dark.

Kitsigianis et al.20 assessed 9 patients before and after the use of cisplatin and concluded that VAT on the horizontal plan is effective to monitor vestibulotoxicity. The reduction of performance of VOR observed in such patients was probably due to chemotherapy.

O'Leary and Davis25 assessed 10 patients with acute condition of Meniere disease and found significant gain increase data in the study of vertical VOR with VAT. The study of horizontal VOR was normal. They noticed that the test was easy to perform even in patients who had acute manifestations.

O'Leary et al.24 assessed two groups of subjects (young and elderly) using VAT in order to compare the results and establish normal values in patients over 65 years. The results of gain in horizontal and vertical VOR was similar in both groups. For the purpose of statistical analysis, there were no statistically significant differences.

O'Leary et al.26, in a study of nine patients with vestibular Schwannoma determined that VAT asymmetry above 3% may be a useful piece of data for the diagnosis of side and size of this unilateral lesion.

Murphy21 compared the results of electronystagmography (ENG) and VAT in 102 patients with vestibular dysfunction in order to determine which test would be more effective in the initial assessment. ENG seemed to be better for initial assessment of the patients after history, physical assessment and audiogram. VAT limitations included inability to localize the side of the lesion and to differentiate peripheral from central lesions, but it may also benefit patients with undetermined vertigo, trauma and in those whose vertigo may not be diagnosed through ENG.

Saadat et al.27 compared the results of cephalic auto-rotation and two-temperature caloric tests in 39 patients with peripheral vestibular alterations and 10 vestibular Schwannoma cases. The result of the study suggested that active cephalic auto-rotation was more sensitive than the caloric test. In cases of vestibular Schwannoma, they all presented abnormal active cephalic auto-rotation test, even those whose origin were from the inferior vestibular nerve and presented normal caloric test results. Conventional caloric test assesses VOR pathway through low frequencies and the horizontal channel only, whereas active cephalic auto-rotation, when used to investigate horizontal and vertical VOR, assesses all three channels in the physiological frequencies of head movement.

Meulenbroeks et al.23 performed VAT in 33 patients to investigate reproducibility and clinical applicability of the method and quantify gain and the VOR phase in normal patients. They concluded that the test is precise and reproducible in the study of VOR for high frequencies.

Caovilla2 assessed 438 patients with vertigo and diagnostic hypothesis of chronic vestibular disease using vectoelectronystagmography (VENG) and horizontal active cephalic auto-rotation with fixed target. In the group, 258 cases (58.9%) presented alterations of VENG and in 180 cases no abnormalities were found. Horizontal active cephalic auto-rotation with fixed target was performed in the group of patients with normal vectoelectronystagmography and it showed normal results for 95 cases (52.8%) and abnormal findings in 85 cases (47.2%).

Hirvonen et al.19 tested 125 patients with horizontal active cephalic auto-rotation with fixed target using HART (Head auto-rotation test) and showed that it is a quick and comfortable test that can be used to study VOR.

Hirvonen et al.18, upon testing the elderly, found alterations in 86% of the cases. More than half of the patients could not perform quick head movements to reach high frequencies. These findings may explain the high prevalence of dizziness and falls in the elderly.

According to Caovilla et al.7, active cephalic auto-rotation alteration as single finding represents 16% of the sample. If associated to vertigo and/or position nystagmus, there were 48.2% of alterations of active cephalic auto-rotation as the only finding at vestibulometry. In vestibulometries, 33.6% did not present any abnormality. The figure goes down to 17% when we perform vestibular tests associated with active cephalic auto-rotation. Active cephalic auto-rotation complements vectoelectronystagmography and computed nystagmography and it may detect abnormalities in vertigo patients who have no positive findings in the other tests.

To Ganança et al.14, gain is a direct measure of sensitivity of VOR. Low gain indicates undercompensated ocular movements, whereas high gain represents overcompensated ocular movements. The phase reflects latency between eye speed peaks in relation to the head. Abnormal gain and phase cause sensation of movement of visual field, oscilloscopy and vertigo. Gain alterations (increase and decrease) were found in horizontal VOR. Agreement between direction of asymmetry and side of vestibular lesion was noticed in 62.9% of the patients and 20.8% presented abnormalities only in the active cephalic auto-rotation test. The cephalic auto-rotation test provides additional information about the functional status of VOR, although it does not differentiate the stages of acute and chronic vestibular diseases, does not differentiate peripheral from central dysfunctions, does not distinguish side of lesion and does not present specific abnormalities for any vestibular disease.

Cephalic auto-rotation is a useful toll to evaluate the results of programs to monitor treatment of patients with vertigo3.

Our sample, in which gain-related alterations were the most frequent ones, is in agreement with other authors.

SYMPTOMS DURING THE TEST

In our sample, 53.5% of the patients presented symptoms during the active cephalic auto-rotation test, and the most frequent one was isolated dizziness in 658 patients (51.4%) (Table 7). The complaint of nausea was present in two patients (0.2%) and nausea associated with dizziness in 14 cases (1.1%) (Table 8). In no case symptoms were more severe than when presented during the crisis, there was no need to interrupt the test and improvement was quick.

O'Leary e Davis25 referred that no patients reported, after the test, nausea or discomfort that lasted for more than a couple of minutes, although these symptoms are common and remain after a long time when caloric tests are performed.

According to Ganança et al.14 the presence of dizziness and nausea during the test is characteristic of patients with vestibular disorders.

CONCLUSION

There was no statistically significant correlation among findings of the horizontal active cephalic auto-rotation test with fixed target in patients with complaints of dizziness and vertigo.

Regardless of patients' age, we did not find difficulties to perform the horizontal active cephalic auto-rotation test.

The most frequently found alterations were those related to gain, either isolated or associated.

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