The amplitude of nystagmus multiplied by its frequency gives a value commensurate to the velocity of slow phase. If the amplitude and the frequency during the visual observation are expressed in relative units (e.g., in points ranging from 1 to 3) the results of multiplication are used for a relative evaluation of nystagmus intensity. The relative evaluation of nystagmus intensity is used to compare the responses and, in particular, to calculate the coefficients of labyrinth asymmetry and of directional preponderance. A suggestion is made to analyze the formal results of caloric tests using a simple graphic model reflecting the left-right interactions by which the obtained coefficients are conditioned

Levashov, M. M.

English

NASA Technical Reports Server

  
 
 
N O T I C E 
 
THIS DOCUMENT HAS BEEN REPRODUCED FROM 
MICROFICHE. ALTHOUGH IT IS RECOGNIZED THAT 
CERTAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RELEASED 
IN THE INTEREST OF MAKING AVAILABLE AS MUCH 
INFORMATION AS POSSIBLE 
https://ntrs.nasa.gov/search.jsp?R=19810014153 2020-03-21T14:20:38+00:00Z
(USA-TA-76409) VISUAL EOALUkTIO* ©P 	 1331-22686
5YSTkGd9S INTENSITY 131 F0I§TS TO D,IAG*USB
VESTIBULAR DISIONCTION (National Aeronautics
and Space Adainistration) 11 p 	 vnclas
5C k02/AF 191	 CSCL 06P G6/52 21900
NASA TECHNICAL 14EMORANDUM
	
NASA TM-76409
VISUAL EVALUATION OF NYSTAGMUS INTENSITY
IN POINTS TO DIAGNOSE VESTTB'jLAR DYSFUNCTION
M. M. Levashov
Translation of "Vizual'naya otsenka intensiv-
nosti nistagma v ballakh dlya diagnostiki
vestibulyarnoy disfunktsii". Zhurnal ushnykh,
nosovykh i gorlovykh bolezney, No. 5,
Sep-Oct. 1979, pp. 29-33
`r"
fo
1
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON D.C. 20546
	 OCTOBER 1980
L Room"	 Afts"Ift NO,
4L TOk OW 6"l
	
•	 Kfit	 TiTILt ►a4E
	 -
i
F
z i
VISUAL EVALUATION OF NYSTA4NUS INTENSITY
INOEINTS TO UxAQNQS g VESTIBULAR DYSFUNC
M.N. Levai7ho•	 y
It. ►OI4401  0*HW1 tN+M *me aW Ad**"	 11"	 a 01we Nw
,SCITRAS
	
YASW-319$
Box 5456	 ii. TWO of	 arw re"Od i+O..M1
\	
Santa Barbara, Cal 93145
	
•	 Trataalation
National Aeronautics and Spica Administration
	
Washington, D.Ci 24544
	
W som"""e M^1r Cod'
ii. i^e^ NMSr
	
.
Translation o#' "Vizual'nsya , otsenka intensivnoati niatagma v
ballakh dlya'diagnostiki vestibulyarnoy disfunktsii".
Zhurnal ushnylch, nosovykh i gorlovykh bolesney, No, x,1979,
PP• 29-33
16. Abrh«t1
The amplitude of nystagmus multiplied by its frequency
is supposed to give a value commensurate to the velocity of
slow phase, one of the most important characteristics. If
the amplitude and the frequency during the visual observation
are expressed in relative-units (e.g. in points range _from
l to 3) the results of multiplication may be used for a relati ve
evaluation of nystaous intensity. 	 •
The relative evaluation of nystaRtnus intensity can be
used to compare the responses and, ir. •particular, .tq calculate
the coefficients o-f labyrinth asymmetry .and of directional
preponderance. It is suggested to analyst the •formal results
of caloric - tests using a simple graphic model reflecting the
left-right interactions by which *she obtained coefficients
may be conditirned.
U. K.r W*Ws eta yr Iwfter(ao
	 M. 01sMMn1M M^NMM
THIS CQP'YRIGHI'ED SOVIET WORK IS REPRO-
•	 • •	 1xaGru ANU SULll BY NTIg
 UNDER LICFNSE
• '	 FRQIt VAAP, Ti p
 WILT COPYRMR' AGENCY
NO FURTHER COPYING IS PE15~lITIFD WITH-
an
1!i i.swlhr t1.s.► !i i-1 MME
NASA-110
^.	 srNIT GNa1, trt Mi a r.^.1 0.
r-3U
nclassified U;lassified	 2
,t
UDC 616.281-61
VISUAL EVAUWMN G' NYSTAl2US INrM=Y IN POINTS
TO DIAGNOSE VESTIBULAR DYSINCTICN
By M. M. Levashav*
The number of special publications that cover an ever more extensive study /29**
of vestibular reactions is rising. A considerable number of than cim be class-
ified with experimental nystagmosetric studies whose realization requires special
equipment. The expediency of such research is quite evident, but in addition
it is necessary to continue development of diagnostic procedures that are sample
and easily realizable in daily practice.
Two indices that have firmly entered nystagmcmetry diagnostics, the coeffic-
ient of labyrinthine synmetry and the coefficient of dire ►;tional dominance of
nystagmus can be considered the necessary mi.ninum without which the caloric tests
have no logical campletion. In order to cag3ute the coefficients it is neces-
sary to evaluate the intensity of each reaction. The rate of the slow component
(RSC) provides the most accurate idea about the intensity, but in a visual
observation it cannot be evaluated, therefore often we are restr%Lad only to
determination of the reaction duration. Such a replacement is quite unequiva-
lent, since there is no correlation between the duration of nystag us and RSC
*ExpWUFE_nta1:Fji1blogica1 Laboratory of the Len•:ngrad Scientific Research
Institute for Diseases of the Lar, Throat, Nose and Such of the RSFSR
Ministry of Public Health
**Numbers in margin indicate pagination in original foreign text
1
(M. M. I,evashav, V. D. Rodionov, A. M. Starosten1to f 1974) .
The task of this report consists of showing a simple method that makes it
possible to visually evaluate the intensity of nystagmus to compute the ooeffic-
ients of labyrinthine asymmetry and directional cdaminuce, as well as pproaches
that facilitate interpretation of the formal results from the positions of
possible pathophysiological concepts.
Nystagnus that is induced by caloric simulation is usually described by the
otorhinolaryngologist &_cording to frequency as "rare," "average" and "frequent,"
and for amplitude--as "small"-, "average"- and "large-scale." The frequency has
dimensions of s-1 , amplitude--degrees, and their product--degrees/s -1 . This
product is close in meaning to the R.9C; therefore it can be used for approximate
evaluation of intensi*y. But for this in the process of visual observation it
is necessary to introduce the element of quantitative assessment. If a word
description is replaced by assessment in points (from 1 to 3), then a real
possibility develops for comparing the reactions with the help of relative eval-
uations of intensity: for example, intensity of nystagmus that is large-scale
(3 points) and average in frequency (2 points) will be evaluated as 3 x 2=6
points.
It remains to stipulate precisely what frequency and amplitude should be
evaluated as 2 points, i.e., what one should consider characteristic for nystag-
rus of average intensity. However, first of all one should solve the question
of the interval in whose limit it is necessary to make the visual evaluation
of nystagmus, since it is known that the reaction can be fairly lengthy, and
each of the characteristics is changed during the reaction, steeply rising to
small values and then gradually dropping. It is desirable to make the evaluation
2
precisely at the section of	 . The dangers of a too great disper-
sion of data on these sections seem groundless. Statistical study of the Em /30
sampling recorded during caloric tests in individuals that do not suffer vesti-
bular dysfunction made it possible to construct samplings of different nystagnus
characteristics on sections of the greatest reaction activity. nie variation
coefficient in the sampling consisting of the average arithmetical frequencies
on the culmination sections equalled 248 (in the sailing of average values of
the frequency for the entire	 _ . LDn it equalled 208) ; the corresponding coeff-
icients for amplitude were 508 and 468. Such a slight difference makes it pos-
siule to restrict the thorough visual observation to the culmination period.
What should one do in order not to miss the culmination during direct obser-
vation of nystapms? Here we again have to return to the norm. LNdmination
an "nxvel" ENG was observed in the interval for 30 to 80 s, counting from the
beginning of irrigation and directly after it. Isere one can limit oneself to
2-3 ten-seoond periods of observation, and then select the greatest from the
results of evaluating intensity.
The specific evaluation in points of frequency and amplitu• is the most
important. In the study mentioned above the arithmetical average frequency on
the culmination section proved to be equal to 2.25 10.07 s-1 . one should prac-
tically evaluate the frequency as bivo points with 19-25 beats in 10 s, and if
the frequency is lower or greater, than respectively 1 and 3 points. It is
easy to compute the frequency with such values, and if it proves to be higher
precise calculation is simply not required, since the evaluation (3 points)
is no longer altered. The arithmetical average for the culmination amplitude
that "narmilly" equals 9.3810.64 (degrees) corresponds to the oscillation of
any very rvAiceable point on the surface of the eyeball or boundary of the
3
iris and sclera roughly by 2 mm. In this case one can evaluate the amplitude
as 2 points. It is convenient to orient oneself on the thickness of a match:
the scopes that surpass this size can be evaluated as 3 points, and those that
are explicitly lower--1 point.
It is necessary to recall that the reliability of the results depends on
how standard the test technique is, and that the numbers presented as the
"normal" were obtained with the use of 250 ml of liquid whose temperature dif-
fered fran the body temperature by 7°C, and irrigation was continued for 40 s.
The use of significantly different techniques of caloric tests can require a
reexamination of the am ants of characteristics subject to the 2-point evalu-
ation, although nothing basically will be changed. The =gmtation that needs
to be made to obtain the coefficient of labyrinthine asymmetry (LA) and direc-
tional dominance (DD) is shown by the formulas where a, b, c and d are the
intensity of the corresponding nystagmuses.
Right Ear Left Ear
Heat test	 a	 b(a+c)-(b+d) X 100 ($)
'(a+b+c4d)^
Cold test	 c	 d	 MD= (a+d) - (b+c) X 100 ( 8 )
a+ ^'
Instead of a certain symbol in evaluating in points one should substitute
the product of the points that evaluates the amplitude and frequency.
The difference in intensity of nystagnuses induced during the tests on the
right ear (a+c) and on the left ear (b+d) that is expressed in peroentages of
the sum of all intensities, i.e., the coefficient of labyrinthine asymmetry
(IA) indicates how great the difference a activity of the right and left
labyrinth is. Asymmetry can be found also in the norm, therefore it is J31
4
reoamnended that those cases where the absolute amount of the coefficient is
more than 208 (Kosoy, 1977) be considered pathological in evaluating the nystag-
mograms. Taking into consideration the lower accuracy of a visual evaluation,
this boundary should be raised to 258. The result with a plus sign is obtained
when activity of the right labyrinth doni ...es (most often as a cansequenoe of
suppression of the activity of the left), and the results with the minas sign--
with the opposite ratios. 7M coefficient of directional dominance that is
cmWted by a similar method evaluates the difference between the intensities
of the right-and left-directed nystagmuses. The dominance of right-directed
reactions yields a result with a plus sign, and left-dinEction-minus. In
contrast to the labyrinthine asymmetry that unequivocally indicates the path-
ology of the labyrinth or the nerve, directional dominance can be found both
during peripheral and during central injuries. A combination of symptoms is
not a rarity. In particular, weakening in the activity of one labyrinth often
is combined with DD of nystagmus directed towards the healthy side.
Below is the result of using the technique in example of one observation,
where the labyrinthine dysfunction was not accompanied by spontaneous nystagmus,
and it was only found in an analysis of the set of caloric tests. During heat
tests the following was obtained: from the right--large-scale nystagmus with
number of beats 20 in a 10-second interval, from the left--small-scale, 19
beats. In the cold test: fron the right--average-scale, 22 beats, from the
left--small-scale, 26 beats. The results of a point evaluation of intensity:
a=3 x 2=6, b=1 x 2=2, c=2 x 2-4, d=1 x 3=3. The coefficients:
IA [(6+4)-(2+3)]:(6+2+4+3) x 1009+338
DD=((6+3)- (2+4)]:(6+2+4+3)x 100=+208
5
One can make a less app ocima ►te evaluation: by introd<icing, for a OMPle,
fractional points for frequency: with mmber of beats in a 10 s000nd segment
up to 17 in lusively--1 point, 18-20 beats--1.5 points, 21-23 beats--2 points,
24-26 beats--2.5 points, and 27 beats area more--3 points.
in the given example with such a refined approach the results are the
following:
Right Ear
	 Left Ear
Heat Test	 3x1.5=4.5	 lxl.5-1.5
Cold Test	 2K2.0=4.0	 1x2.5=2.5
LA= ( (4.5+4.0) - (1.5+2.5) ] : (4.5+1.5+4.0+2.5) x 100+36$
DD-[(4.5+2.5)-(1.5+4.0)]:(4.5+1.5+4.0+2.5) x 100=+12%
The refined evaluation stressed the importance of LA and reduced the M.
Under what conditions could precisely such a correlation of intensities
be formed? We will present the interrelationships between the right and left
vestibular nuclear complexes (NC) in the fora of a relatively simple plan
(Figure) , and will examine them in calcaric tests where changes occur in the
afferent streams entering the vestibular nerves from the labyrinths. The plan
naturally is only a simplified model but it is based on assumptions that do
not contradict the facts that are kncewm in experimental and clinical labyrin-
thology. We will list these assumptions.
1. The intensicy of nystag us (its R.9C) in the caloric test depends only
on what the absolute amount is for the difference in Levels of activity of
the right and left vestibular NC at the given moment, and the direction-ern
its sign.
6
m..	 z
K	 L
Figure. Plan for Interrelationships of Right (R) and Left (L) Vestibular Camp-
lexes During Pathology of Left Labyrinth
Key: on x axis--utriculopetal (+) and utriculofugal (-) cupulo-endolymphAatic
shifts (relative units)
on y axis---level of activity of nuclear complex formed of natural activity
(hatched) and afferent streams entering on VIII nerve (relative units).
Differerve in levels R-L during tests roughly correspotr3s to intensity of
nystagmus in points (positive--during nyst&gftMS to the right, negative--
to the left) .
2. the level of activity of each NC is the sum of the natural activity
and the afferent strewn entering on the vestibular nerve. The first is altered
only on large tine segments, and therefore during the test can be considered
constant. The afferent stream fran the labyrinth outside the test corresponds
to a certain stable level of spontaneous impulses, while during the test it
is altered only under the influence of cupulo-endolyn#mUc shifts.
3.the dependence of the change in impulse frequency in the afferent stream 	 /32
on the size of the shift can be represented by a certain S-shaped curve; at the
same time during standard caloric tests changes normally occur in the limits
of its linear section.
7
4 . during pathology the afferent stream of nerve impulses on the gainful
side in response to a stimulus is altered differently than ors the healthy side.
In the given =m ple (Figure) the change in the reactivity of the left labyrinth
is expressed in a reduction in the curvature of the characteristic curve, as a
aonsequenee of which there was a decrease in the frequency of spontaneous im-
Pulses•
S. the decrease in the level of spontaneous impulses is aaaoipanied by a
disorder in equilibrium between the MUMMY levels of activity from the right
and from the left. In the given example the level of activity from the left
Proved to be lower than from the right. Without cagpensation such a difference
in the level would result in the appearance of	 nystagcus to the
right. However, after changes on the periphery compensation for the disrupted
equilibrium occurs, 1weling of the activity levels by reinforcing the nuclei
in the painful side due to the natural activity of the intact NC. The absence
of spontaneous nystagmis is a sign of complete or almost complete compensation.
We will assume that the cupola-endolymphatic shifts that are induced by
warmth or oold corrkspend to two divisions on the x-axis. From the right with
such shifts the warmth will induoe an increase in impulses over the spontaneous
level in the afferent stream roughly by four units on the y-scale, while cold--
a decrease by the same amount. From the left the corresponding increase and
decrease will =prise roughly bK) units. With complete oaapen ation, i.e.,
with the same levels of summary activity in the right and left NC, the warm
and cold nystagauses from the right would be the same in intensity. however,
r
	 in our example they differ by 0.5 Points. This occurs for the following
reason. The intensity of nystag= depends on the difference in levels, while /33
8
the level of smeary activity of the right NC outside the test is somewhat lower
than the right, due to insufficiently crnplete	 Asa cm _ _uc►nce
of this conditions are created for the foamatian of warm nystagaus during the
test on the right ear that are somewhat more favorable than for the cold, and
its intensity is greater than the intensity governed only by the increase in
the afferent stream. The intensity of cold nystagnis from the right was corres-
pondingly reduced by the same amount. Analogous reasons govern the difference
in intensities of warn and cold nystagai m from the left; at the same time, on
the contrary, the warn nystagxus is less intensive here.
Ttura, calculation of nystagtus intensity during a set of caloric tests is
a source of valuable diagnostic information; at the same time in order to eval-
uate intensity one can use a visual observation, while a simple model helps to
present the possible mechanisms that governed a certain formal result of nystag-
monetric examination of the patient.
Levashov, M. M.; Aodionov, V. D.; and Starostenlw, A. M. in ; ornn ►e may,
Vestibulvarnaya funkts&a. Ob'vedin. Nauchn. ov "Fiziolm4a cheloveka i
zhivotnykh- ["Sensory Systems. Vestibular F<uyctioan. United Scientific —Counsel
"Physiology of Man and Animals"], USSR Academy of Sciences, Leningrad, 1974,
p 15-72.
Kosoy, J. Acta OtalaryMol., 1977, Suppl. 343, p 57.
9
k ; _.	 ----	 -_ -	 -


Visual evaluation of nystagmus intensity in points to diagnose vestibular dysfunction

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server