Keywords
vertigo - electronystagmography - physiological nystagmus
Palavras-chave
vertigem - eletronistagmografia - nistagmo fisiológico
Introduction
The Otoneurology is the science that studies the auditory and vestibular system, its
expansion and relations with the central nervous system. To maintain the balance needed
multiple peripheral and central systems, beyond the end organs and nerves labyrinth[1].
Vertigo is the most common symptom of a vestibular dysfunction, while their most frequent
signs are the spontaneous nystagmus (SN) and voluntary eye movements and abnormal[2].
The otoneurological is accomplished through a set of procedures which includes medical
history, ENT examination, audiologic and vestibular[1].
In assessing vestibular eye movements are recorded through tests such as electronystagmography
(ENG). It is based on the uptake of corneal-retinal potential, environmental influences
likely to suffer physiological and pathological conditions[3].
The vectonystagmography (VENG) is the improvement of ENG in which two channels were
added, allowing for improved characterization of eye movements, especially the nystagmus
and is still able to assess most of the supranuclear ocular motor systems and record
the movements Eye on the various tests that are part of the assessment battery vestibular-ocular[4]
[5].
By means of specific methods associated with computer records of nystagmus was possible
to obtain greater precision and comparing the intensity of the different stimuli received
in the various tests and assessments, better visualization of nystagmus and effective
data archiving[6].
During the frontal fixation of gaze nystagmus can occur both eyes open and eyes closed,
what is called the NE. In normal patients may experience the onset of horizontal nystagmus
with closed eyes VACL less than or equal to 6°/s[7].
The presence of NE, together with complaints related to balance is a sign of pathological
vestibular disorder[8], and for other authors, even without complaints, the presence of this may indicate
problems in the functioning of the vestibular system[9].
The NE can modify the degree of the results of rotational chair testing (PRPD) and
caloric test, directional preponderance causing the same side of nystagmus[10], and cause directional asymmetry than the limit of the normal pattern of post-caloric
nystagmus[11].
In cases with abnormalities of post-caloric nystagmus in caloric tests in air at 42
and 18° C, it was found that stimulation by cold (10° C), the influence of NE may
be withdrawn in most cases, showing that through this we can identify abnormalities
that are not observed and further confirmed unilateral vestibular hyporeflexia[12].
Thus, the study of spontaneous nystagmus with eyes closed (NEOF) becomes relevant
since it can modify the results obtained during some evidence of vestibular[10]
[12], leading to wrong conclusions from it. Studies have shown that the presence of eye
movement, even in the absence of complaints may indicate vestibular problems, besides
being the most frequent sign in vestibular disorders and for the evaluation of this
system. Moreover, the scarcity of specific research on the subject in literature,
especially in our community, motivated us to assess how the NE influences the assessment
of patients with chronic peripheral.
This study aimed to characterize patients and type of influence NEOF in tests of digital
VENG in patients with chronic peripheral vestibular dysfunction.
Method
It was a retrospective study that relied on survey charts of patients who underwent
the test with a digital VENG, in the years 2000 to 2007, with approval of the Ethics
Committee of this institution (protocol number 1562/07).
To select the sample, were analyzed tests of vestibular function with caloric vectonystagmography
digital air (both Neurograff Eletromedicina Ind. e Com - EPT - Brazil).
We included subjects aged from 18 years, regardless of gender, presence of NEOF and
caloric test, complete with hot and cold stimulation, with complaints of chronic dizziness
of peripheral origin.
From this sample, those who showed abnormal vestibular central origin or associated
with abnormal ocular motility were excluded.
Patients should necessarily have been submitted to ENT examination, medical history,
physical examination and audiological assessment consisting of pure tone audiometry,
speech audiometry (SRT and SDT) measures of acoustic immittance and acoustic reflex
testing, but his analysis is not part of this study.
Before evaluation, patients were asked to remain fasting four hours before the exam,
avoid stress, fatigue, smoking, drugs or medicines as painkillers, tranquilizers and
anti-vertigo, chocolate and beverages containing caffeine (like tea, coffee, soft
drinks ) or alcohol three days before the evaluation[3] and not wear contact lenses, makeup or face creams on exam day.
Tests included: research on positioning and positional nystagmus, eye movement calibration,
NE (made in fixing the front look with eyes open and closed), semi-spontaneous saccadic
movements, pendular tracking, optokinetic nystagmus, rotatory test pendular and caloric
test with air at 42° and 18° C and in some cases, at 10° C.
In the caloric test the patient was supine with the head elevated at 30° and was instructed
to perform mental activity for no cortical inhibition during the test. The evaluation
was performed by means of thermal stimulation in the ears separately, with air at
42° and 18° C for 80 seconds, with intervals of three minutes between stimulation
and another.
The presence of NEOF and / or pre-caloric and its influence on test results were investigated,
besides the characterization of his VACL, its direction and symmetry of the evidence.
The criteria for performance and interpretation were based on pre-established values[1] for use of this equipment[1].
From the data collected, comparisons were made between genders, ages, angular velocity
and direction of spontaneous nystagmus, caloric test results and completion of entrance
examination.
After sample collection, the results were analyzed statistically. We used the Test
of Equal Proportions and two p-value <0.005 was considered statistically significant.
Results
We analyzed 373 patients attended the entrance examination for the years 2000 to 2007
with the presence of NEOF. Of the 373 tests analyzed, 300 met the requirements for
inclusion.
The sample comprised 73.7% females and 26.3% were male, and the difference between
the sexes was statistically significant.
Regarding age, subjects were divided into age groups: 4.33% ageless, 1.33% of 18-20
years, 21-40 to 14.67%, 43.33% of 41-60, 34, 67% 61-80% 80-100 1.67. The age of 41-60
years had significant values in comparison to other ages.
Characteristics of NEOF, we found that the direction was more prevalent horizontal
to the right, being significant in relation to others ([Table 1]).
Table 1.
Distribution of the direction of spontaneous nystagmus with eyes closed the whole
sample.
|
|
Direction of spontaneous nystagmus with eyes closed
|
|
|
|
Horizontal to right
|
Oblique to right downward
|
Oblique to right upward
|
Horizontal to left
|
Oblique to left downward
|
Oblique to left
|
Vertical downward
|
Vertical downward upward
|
|
Quantity
|
138
|
26
|
18
|
96
|
13
|
6
|
2
|
1
|
|
%
|
46.0%
|
8.7%
|
6.0%
|
32.0%
|
4.3%
|
2.0%
|
0.7%
|
0.3%
|
|
p-value
|
< 0.001
|
|
|
|
|
|
|
|
It was noted that most individuals presented VACL smaller than the 7°/s (86.6%), which
was statistically significant than the cases with more than VACL 7°/s (12.33%). 1%
showed vertical nystagmus and had no measure of VACL, since it was used in this study
only VACL average values related to the first channel of record VENG. In 86% of individuals
who had some kind of influence NEOF the VACL of NEOF was lower than the 7°/s and 14%
was equal to or greater than the 7°/s.
The other stages of vestibulometry were analyzed, but there were no influences of
NEOF.
Of the total sample, 59% had some kind of influence caused by NEOF in the caloric
and 41% had not had any influence, the difference being statistically significant.
The NEOF influence the answers of caloric tests in the following ways: hyperreflexia,
hyporeflexia, reversal of the nystagmus, abnormal PL, NDP abnormal in conventional
tests (hot and cold) and the calculation of symmetry in the cold caloric test.
Inversions were observed unilateral post-caloric nystagmus in 14% and 86% of patients
were not observed inversions, and the absence of this finding was statistically significant.
Reversals of the post-caloric nystagmus occurred in the opposite direction to that
expected in all cases with this type of influence, ie to beat the same side of the
eye movement. All inversions were unilateral and in some cases, occurred in more than
one stimulation. All presented the findings of the hot caloric test, and 2.3% were
also on caloric cold, ear opposite the hot race that appeared in and 11.9% were also
frozen at the caloric test on the same side that appeared in the test cold. Statistical
analysis showed that the inversion in the warm caloric test had a statistically significant
value compared to the same stimuli found in cold and icy.
There were no significant values when comparing the reversal by the influence of laterality
NEOF and the three temperatures.
In warm caloric test, we observed normoreflexia values (between 2°/s and 19°/s) in
72.3%, 3.3% hyporeflexia, hyperreflexia (values above 19°/ s) 10.3 % and inversion
(right or left ear) in 14%. The normoreflexia obtained a statistically significant
value in relation to other abnormal findings.
In cold proof, 46% presented normoreflexia, 2% hyporeflexia, hyperreflexia 49.7% and
2.3% reversal of post-caloric nystagmus. The most prevalent response was “hyper-reflexia,
but this was not considered statistically different from the percentage of response”
normoreflexia “but in relation to others, hyperreflexia showed statistically significant
values.
Of those who had hyperreflexia in the warm caloric test, 32.3% had bilateral hyperreflexia
and 67.7% unilateral, and 66.7% for the same side in NEOF, and 33.3% for the opposite
NEOF In both cases the values were significant.
Of those who had hyperreflexia in the cold caloric test, 63.8% had bilateral hyperreflexia
and 36.2% unilateral, and 74.1% for the same side in NEOF, and 25.9% for the opposite
NEOF. Both values were statistically significant.
Of the 51 who had SVPD, we observed that 36 had lower values and showed no inversions.
In the analysis of data from the hot caloric test, 58.3% showed reduced values for
the same side of NEOF, while 41.7% showed these values to the opposite side. In the
analysis of data from the cold caloric test, 41.7% showed reduced values for the same
side of NEOF and 58.3% had values for the opposite side. The values were not statistically
significant.
On completion of entrance examination, we obtained 36.0% with EVN, 4.7% with the IPVS
D, 5% with the IPVS And BIPVS with 28.7%, 7.7% with the SVPD D, 6.7% SVPD with the
E, with 2.7% and 8.7% SVPDB as inconclusive. The most frequent finding was the normal
vestibular tests, which was statistically significant compared to other conclusions.
However, when analyzing the statistical test results, we observed that this percentage
cannot be considered statistically significant considering the percentage of completion
of BIPVS, present in 28.7% of cases.
In warm caloric test, among the 36 who presented the final conclusion SVPD, 58.3%
had lower values for the same side of NEOF and 41.7% had lower values for the opposite
side. Already in the cold caloric test, 41.7% had lower values for the same side of
NEOF while 58.3% had lower values for the opposite side. In both tests there were
no statistically significant values.
In analyzing the relative values of the caloric test of the whole sample, comparing
the values of hot and cold stimulation, 28.3% and 29.3% had NDP PL. Of the 116 who
took the cold caloric test, was calculated at 33.7 the NDP (symmetry), and 8.7% of
the total sample could not perform any calculation. There was no significant values
in this analysis.
Of individuals who had the NDP, 82% were normal, while 18% had abnormal results. NDP
60% had changed to the same side of NEOF, and 40% for the opposite side of NEOF.
LP was observed in 78.4% normal and abnormal in 21.6. 42.1% PL was changed to the
same side of NEOF and 57.9% in the PL was changed to the opposite NEOF.
Comparing the abnormal values of the NDP, PL, hyperreflexia and hyporeflexia at 42
and 18°C, we observed that when compared with NDP MP and NDP with hyperreflexia, no
statistically significant figures, but the NDP compared with PL, hyperreflexia and
hyporeflexia at 42° and 18°C value was significant. By comparing PL with hyperreflexia
and hyporeflexia at 42° and 18°C, it was verified that these were statistically significant.
Comparing hyperreflexia and hyporeflexia 18° and 42° C there was no significant value.
Of the total sample, 38.7% of subjects underwent caloric frozen while 61.3% did not
accomplish, and those who did not undergo the cold caloric test, statistically significant
compared to those who carried out this test.
In calculating the NDP of the 116 who took the cold caloric test (10°C), 56.9% had
symmetry of responses (30%), 30.2% showed asymmetry and 12.9% could not perform any
calculation therefore 4.3% had unilateral reversal of post-caloric nystagmus, and
8.6% in this test was done only in one ear (the same one that was influenced by the
cold stimulation). It was concluded that the symmetry in the calculation of PDN was
statistically significant compared to other findings in this test.
In 57.8% of subjects who underwent caloric ice was observed some kind of influence
NEOF, while 42.2% did not. Those who had some kind of influence NEOF were significant
compared to patients without influence.
Of the 67 who had some kind of influence NEOF and held the cold caloric test, 79%
was reached on a final exam, and you can say that in these cases was the influence
of NEOF withdrawal, while 21% were inconclusive as because it was not possible to
remove the influence of NEOF. The tests were inconclusive, and higher prevalence were
statistically significant in relation to inconclusive.
Of the 116 who took the cold caloric test, it was possible to reach a conclusion only
in 80.2% and 19.8% remained inconclusive. Those who could reach a conclusion, the
values were statistically significant in relation to inconclusive.
By comparing the cold caloric test results related to the NDP as symmetrical or asymmetrical,
or reversal test performed only in one ear, it was observed that the comparison of
values between NDP symmetric with asymmetric findings, inversion and test performed
only in one ear, was statistically significant, the values of the comparison between
the NDP and reversal with asymmetric caloric test only in one ear were also statistically
significant, and comparing with reversal test performed in only one ear had no significant
values ([Table 2]).
Table 2.
P-values comparing the caloric test results cold (10 degrees C).
|
Caloric cold (10 degrees C)
|
NDP symmetric
|
NDP asymmetric
|
Inversion
|
|
NDP asymmetric
|
< 0.001
|
|
|
|
Inversion
|
< 0.001
|
< 0.001
|
|
|
Test in one ear
|
< 0.001
|
< 0.001
|
0.182
|
Discussion
The study population consisted of mostly women (73.7%), with a mean age of 55.08 years.
These findings were similar to those found by several authors[12]
[13]
[14]
[15]
[16]
[17].
The direction was more prevalent NEOF the horizontal to the right, with significant
values compared to other directions, a result similar to those found in the literature[8]
[12]
[18]
[19].
We find the values of VACL NEOF smaller than the 7°/ s in 86.7% of the total sample,
and 86% of those who had some kind of influence NEOF VACL also showed less than 7°/
s. In both comparisons, these values were statistically significant. Stands out, so
that the NEOF, even presenting within the normal range, influenced the majority of
examinations, becoming thus the finding of relevant importance, requiring greater
caution when performing the examinations and tests confirm the diagnosis for an individual
who fails to do so in error, since the influence can change significantly the responses
of post-caloric nystagmus.
In surveys analyzed, were found only in NEOF influences caloric test. Some authors
stated that the preponderance NE may lead to the same side of nystagmus[10], and can cause directional asymmetry than the limit of the normal pattern of post-caloric
nystagmus[11].
In warm caloric test, it was observed as a result normoreflexia most common (72.3%)
and 66.7% was found hyperreflexia in the same direction of unilateral NEOF. In cold
test, 49.7% had hyperreflexia, and unilateral in 74.1% in the same direction NEOF.
In all analysis values were statistically significant, similar to the literature[18]
[20].
According to the authors NE could, algebra, it can be added or subtracted on the post-caloric
nystagmus. This was not observed in this study, since even very small values of the
VACL NEOF also caused hyperreflexia, at different rates quoted by the author.
Among patients with PDN (15%) or PL (21.6%) abnormal, we find values similar to those
found by several authors[12]
[20]. The NDP may reflect the effect of NEOF or may be associated with hyporeflexia or
unilateral Bilateral[21]. The NDP occurs when the response of post-caloric nystagmus is greater for one direction
than another. In his clinic, found that the NDP was more prevalent in patients with
strong IR[22].
The conclusions of VENG more prevalent in this sample were: EVN and BIPVS, both being
statistically significant when compared to other conclusions, but there was no difference
between the two, similar to the literature[18]
[23]. Even before the examinations within the normal range, we can not say that this
outcome is the same in the absence of NEOF, which could influence the caloric responses,
decreasing the values opposite him, or override the direction in which it occurs,
masking, so the actual values of this test.
It was observed that the population of those who carried out the cold caloric test
was lower than in individuals who did not perform this test, showing that is not widely
used, as reported in the literature[24]. However, it can be stated that the cold caloric test was efficient in the removal
of the influence of NEOF since after their application has been possible to reach
definitive conclusions in 79% of those who had some influence NEOF and underwent this
stimulation, according to the literature that the findings prove ice provides the
most reliable diagnostic[12]
[13]
[14]
[15]
[16]
[17]
[18]. Moreover in some cases the influence of NE can not be removed even when performed
cold caloric test[21].
Thus, it was possible to verify that the evaluation and detailed minusciosa NEOF is
required since this causes interference relevant during testing of the caloric test,
resulting in erroneous or misleading conclusions, and interesting to conduct more
specific studies in this area.
Conclusion
Given the findings of this study in patients with chronic peripheral vestibular dysfunction
and presence of digital NEOF VENG can conclude: NEOF most common type was horizontal,
with VACL smaller than the 7°/ s, which influenced the majority of examinations and
only the results of the air caloric test with reversal of post-caloric nystagmus,
hyperreflexia and hyporeflexia, NDP and PL altered; the findings were more prevalent
and BIPVS EVN, and the cold caloric test (10 C) removed the influence of NEOF in most
of the individuals who performed, allowing to reach a final conclusion.
