Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6044_Библиотеки_им_академика_М_И_Перельмана.pdf
168
Although measurements of quiet stance may contribute to separation of groups
of subjects with different lesions, the normal variations are so wide that classifi cation of individual responses and, hence, clinical usefulness becomes ambiguous. To
master such shortcomings, different techniques to increase the demands on the
postural control are applied. The idea is that if there is a defi cit in the postural control system that is not evident because of the redundancy and adaptability of the
systems, the defi cit will become evident if further sensory information is lost or
distorted. The classical Romberg test uses evasion of visual clues to load the postural system. Likewise, posturography can be performed and results compared with
open and closed eyes. This is a standard procedure used in most test set-ups [ 10 ]. If
the increase of sway compared to normals is greater with open eyes than with closed
eyes, this might be taken as suggesting less effective use of visual clues and may be,
but not unequivocally, interpreted as a sign of decreased CNS function. A foam rubber pad can be positioned between the feet of the subject and the forceplate to
reduce mechanoreceptor sensation from the soles of the feet and increase the
diffi culties in stabilizing the body. The patient can be asked to place his head in
different positions to increase diffi culties with vestibular cervical interaction.
The role of static posturography in body sway assessment still has a limited
clinical use because of its intrinsic high variability which does not permit a reliable
diagnosis. There are no reports concerning the intersubject coeffi cients of variation
(CV) of static posturography parameters in healthy subjects. In order to make static
posturography a reliable clinical tool, it is necessary to use parameters with a CV
lower than 15 %. It is possible using ‘sensory ratio’ formulas, like sensory integration tests of the EquiTest equipment, which is probably the most widespread
commercially available equipment that utilizes six sets of disturbed sensory information to estimate a sensory integration set.
It is possible to calculate similar ‘sensory ratio’ with standard static posturographic equipments including values from the unstable condition on foam pads.
According to Di Berardino et al. [ 11 ], the most reliable parameters in static
posturography were given by the use of bilayer rubber foam pads. The CV of the
visual and vestibular percentages were about 10 %. Therefore, the lowest variability
suggests that these percentages derived from the ‘sensory ratios’ using bilayer foam
pads, together with somatosensory one that was about 14.4 %, are the most acceptable parameters for clinical use. Furthermore, the role of ‘sway-related’ tests with
foam pads, proposed by Allum et al. [ 12 ], is fundamental in order to make static
posturography more useful.
16.2 Posturography with Induced Perturbations
Balancing is often investigated in response to three external mechanical stimuli,
which are body-support surface tilt, surface translation, and contact force (e.g. a
push or pull having impact on the body).
M. Magnusson and A. Hahn
169
To further load human postural control with the purpose of revealing defi cits, the
standing subject may be exposed to different perturbations, and the responses to
recover quiet stance are evaluated.
In the T-Post system from Toennies, the subjects stand, leaning somewhat
backwards, and the platform then tilts and induces a further backward movement of
the body. The subjects have to move forward to avoid falling; latencies and
amplitudes of this movement can be combined with EMG recordings to estimate
response latencies. The method can detect movement and probe synergistic muscle
activity if combined with EMG. In the motor coordination test of the EquiTest, the
platform is either tilted or translated with different velocities, and the postural
reactions of the subject are measured.
Vibration toward the antigravity muscles induces a sensation of movement and
involuntary body movements [ 12 ]. This has been used to perturb the standing
human for diagnostic purposes, calculating vibration-induced body sway (VBS).
Patients with posterior fossa lesions are reported to have larger responses when
vibrated toward the neck muscles than the calf muscles, compared to subjects with
vestibular lesions. Vibration toward the calf muscles according to a pseudorandom
binary stimulus (PRBS) induces an on- and off-going perturbation which can be
used to estimate an input–output relation and model postural control, which allows
estimation of the so-called characteristic parameters of postural control. Comparing
these parameters, one can get an estimation of the postural control of the subject.
The use of these parameters can distinguish, for example, between an acoustic neuroma and an acute vestibular lesion and also distinguish subjects with cervical disorders. Patients who recover from hemispheric stroke demonstrate remaining
differences in postural control when evaluated with those parameters [ 13 ].
A vestibular spinal perturbation may evoke both lateral and anteroposterior body
sway by galvanic stimulation of the vestibular nerves. Evaluation of these responses
may give further information in posterior fossa lesions, but so far clinical studies are
lacking. Visual stimulation inducing a sensation of small amplitude translatory
movements of the surroundings may induce perturbations in the anteroposterior
plane, which, not surprisingly, differs in subjects with cerebellar lesions [ 14 ]. The
effect of visual stimulation, however, may be dependent on attention and state of
mind, and different patterns of response may be assumed in normal subjects. So far
visually induced perturbations, with the exception of the so-called stabilized visual
frame in EquiTest measurements, have not been used in clinical routine to the
knowledge of the author [ 15 ] .
References
1. Baloh RW, Honrubia V (2001) Clinical neurophysiology of the vestibular system, 3rd ed.
Oxford University Press, New York; Trauma, pp 322–332
2. Brandt T, Krapczyk S, Malbenden L (1981) Postural imbalance with head extension.
Improvement by training as a model for ataxia therapy. Ann N Y Acad Sci 374:636–649
16 Whiplash Effects on Postural Control
170
3. Forth KE, Metter JE, Paloski WH (2007) Age associated differences in postural equilibrium
control: a comparison between EQscore and minimum time to contact (TTCmin). Gait Posture
25:56–62
4. Clark S, Riley MA (2007) Multisensory information for postural control: sway-referencing
gain shapes center of pressure variability and temporal dynamics. Exp Brain Res 310:
176–299
5. Nashner LM, Black FO, Wall C 3rd (1982) Adaptation to altered support and visual conditions
during stance: patients with vestibular defi cits. J Neurosci 2:536–544
6. Riley MA, Baker AA, Schmit JM, Weaver EE (2005) Effects of visual and auditory short term
memory tasks on the spatio-temporal dynamics and variability of postural sway. J Mot Behav
37:311–324
7. Baloh RW, Jacobson KM, Beykirch K (1998) Static and dynamic posturography in patients
with vestibular and cerebellar lesions. Arch Neurol 55:649–654
8. Contarino D, Bertora GO, Bergmann JM (2003) Balance platform: mathematical modeling for
clinical evaluation. Int Tinnitus J 9:23–25
9. Di Fabio RP (1996) Meta-analysis of the sensitivity and specifi city of platform posturography.
Arch Otolaryngol Head Neck Surg 122:150–156
10. Shumway-Cook A, Horak FB (1986) Assessing the infl uence of sensory interaction of balance:
suggestion from the fi eld. Phys Ther 66:1548–1550
11. Di Berardino F, Filipponi E, Barozzi S, Giordano G, Alpini D, Cesarani A (2009) The use
of rubber foam pads and “sensory ratios” to reduce variability in static posturography
assessment. Gait Posture 29(1):158–160
12. Allum JHJ, Zamani F, Adkin AL (2002) Differences between trunk sway characteristics on a
foam support surface and on the Equitest1 ankle-sway-referenced support surface. Gait Posture
16:264–270
13. Horak FB, Henry SM, Shumway-Cook A (1997) Postural perturbations: new insights for
treatment of balance disorders. Phys Ther 77:517–533
14. Dehail P, Petit H, Joseph PA (2007) Assessment of postural instability in patients with
traumatic brain injury upon enrolment in a vocational adjustment programme. J Rehabil Med
39:531–536
15. Magnusson T (1994) Extracervical symptoms after whiplash trauma. Cephalalgia 14:
223–227
M. Magnusson and A. Hahn
171
D.C. Alpini et al. (eds.), Whiplash Injuries,
DOI 10.1007/978-88-470-5486-8_17, © Springer-Verlag Italia 2014
17.1 Static Posturography
The quiet upright position (Stance) is controlled by three distinct sensorial cues
organs: visual, somatosensorial (from skin and pressure sensors in the feet) and
vestibular (mainly from otolithic maculae).
Posture is more stable when all the sensory systems operate. However, the weightening of each cue is adjusted in the vestibular nuclei and cerebellum [xxx] according
to the surface, the environment and the task. SOT test (see part I) is designed to
investigate the specifi c weightening of different cues in stance control. The sequence
of posturographic test adopted is aimed to investigate postural interactions between
sensorial cues, ranging from complete sensorial control (eyes open standing on a
solid surface) to quite exclusively pure vestibular control (eyes closed standing on
foam). Inputs from the vestibular canals and somatosensory system stabilize posture
more effectively at higher frequencies of body sway, while visual and otolith-organ
signals are more effective at lower frequencies. The amplitude threshold for detection of body sway differs between senses: the somatesthesic senses have the lowest
threshold, vision the next and the vestibular system has the highest threshold.
Whiplash can affect the balance system through an involvement of one or more
of these structures:
1. The neck proprioceptors
2. The peripheral vestibular system
3. The central vestibular system
P. L. Ghilardi • A. Casani • B. Fattori
Institute of Otorhinolaryngology, University of Pisa, 56100 Pisa, Italy
R. Kohen-Raz
The School of Education, The Hebrew University of Jerusalem, Har ha-Tsofi m ,
Jerusalem, Israel
D. C. Alpini (
*)
ENT-Otoneurology Service , IRCCS “Don Carlo Gnocchi” Foundation , Milan , Italy
e-mail: dalpini@dongnocchi.it
1 7
Static Posturography and Whiplash
P. L. Ghilardi, A. Casani, B. Fattori, R. Kohen-Raz,
and D. C. Alpini
172
After whiplash, an abrupt increase in discharge from the neck proprioceptors,
usually asymmetric, might be generated by an overexcitation of the sympathetic
fi bres related to the B receptors of the deep cervical erector muscles [ 1 , 2 ].
Several studies have reported altered postural control in people with neck pain
and disturbances in static balance have been demonstrated [ 3 ].
Non-specifi c neck pain or whiplash-associated disorder (WAD) exhibit greater
postural instability than healthy controls, signifi ed by greater COP excursions irrespective of the COP parameter chosen. In particular, COP excursions are particularly increased in WAD compared to healthy individuals.
Further, the decreased postural stability in people with neck pain appears to be
associated with the presence of pain and correlates with the extent of proprioceptive
impairment, but appears unrelated to pain duration [ 4 – 6 ].
Post-traumatic vertigo is not a clinical entity, but this term refers only to the common aetiology of a heterogeneous collection of vestibular disorders. Even if there
are many convincing signs indicating the existence of anatomical and functional
connections between the neck and the vestibular system, the assessment of vertigo
after whiplash is extremely complex. No reliable clinical, electronystagmographic
or posturographic test exists to confi rm the linkage between the neck trauma and the
vertiginous symptoms.
Keeping these observations in mind, static posturography could provide useful
information about the postural conditions of patients suffering from vertigo after
whiplash.
Before the introduction of computerized posturography (PG), the VSR was
studied using various tests (Romberg, Fukuda, Unterberger, Babinski-Weil, Ataxia
test battery, etc.) which nevertheless do not permit a quantitative and objective
study of postural function. Falls and diffi culties in dynamic task, such as single-leg
stance with eyes closed, the step test, tandem walk on a fi rm and soft surface, stair
walking and the timed 10 m walk with and without head movement, have also been
reported [ 7 ].
Routinely, posturography (PG) recording is performed under two basic
conditions:
1. Patient standing on the platform with eyes open (EO)
2. Patient standing on the platform with eyes closed (EC)
Besides these basic tests to verify the presence of a latent postural disorder, other
destabilizing tests are usually employed. We use two types of examinations to
verify this:
1. Patient standing on the platform with EC and with the head in extreme retrofl ex-
ion (EC-HER)
2. Patient standing on the platform with EC immediately after head shaking
(EC-HST)
The parameters we can achieve from the computer elaboration are shown in
Table 17.1 . An important difference between the PG and the older techniques for the
study of posture is that the former provides us with precise objective data which can
be compared throughout time for each patient and each with different pathologies of
balance.
P.L. Ghilardi et al.
173
In this context, PG, performed with particular types of stimuli or provocation
tests, may identify a cervical origin of the dizzy symptoms. Through tests performed
with rotation (“cervical dynamic activation”) [ 8 , 9 ], “head turned” [ 10 ] (Fig. 17.1 )
and retrofl exion of the head [ 11 ] (Fig. 17.2 ), it will be possible to obtain some infor-
mation on how cervical inputs can generate instability syndromes. However, positive results obtained with the above-mentioned tests must be evaluated within the
entire clinical context because they cannot be considered as pathognomonic.
Table 17.1 The main parameters and the graphic elaborations obtained by computer, the role of
the proprioceptive inputs in patients suffering from postural disorders
Parameters Graphic elaborations
X min, max, mean Displacement of pressure centre on X axis
X min, max, mean Displacement of pressure centre on Y axis
Velocity of the sway Its standard deviation is an index of the “homogeneity” of the postural
oscillations
Length L (mm) Total sway path of centre of pressure
Surface S (mm
2
) Is indicative of the precision of the system
L.F.S. Correlation function between L and S
Statokinesigram Area covered by the sway
Stabilogram Displacement on time of the sway for X and Y
Fast Fourier transform
Romberg’s index Ratio between the same value with EC and EO
This allows a quantifi cation of the importance of the pressoreceptor system for balance and provides us with useful information for the management of rehabilitation treatment
–1.0 cm–2.0 cm
Ref.: centre of gravity positionRef.: platform
a
Statokinesigram
Fig. 17.1 ( a–c ) Patient suffering from vertigo from WI. ( a ) Normal result in EO. ( b ) The SKG is
abnormal when the head of the patient is rotated towards the right. ( c ) A similar pattern can be
observed with the head rotated to left
17 Static Posturography and Whiplash
174
Armato and Ferri [ 12 ] published a study on 569 patients with whiplash, with or
without associated head injuries. Of these, 21 % had either normal vestibular functioning or only static stabilometric alterations that were compatible with a modifi ed
proprioception of the cervical spine.
Cobo et al. [ 13 ] investigated 99 women. Fifty-four women had suffered whip-
lash within 2 weeks and 45 were included in a healthy control group. Static
Fig. 17.1 (continued)
–3.3 cm
–2.0 cm
Ref.: centre of gravity position
Ref.: platform
c
–2.2 cm
–2.0 cm
Ref.: centre of gravity positionRef.: platform
b
P.L. Ghilardi et al.
175
Fig. 17.2 Patient suffering from WI. Above , the pathological SKG in EO-HER; below , the SBG
shows a prevalence of the oscillation on the anterior-posterior axis
–2.6 cm
Statokinesigram
–2.0 cm
Ref.: centre of gravity positionRef.: platform
Stabilogram
X mean
–0.3 mm
X mean
–50.0 mm
22.4
D
S
A
I
13.5
4.5
–4.5
–13.5
–22.4
(mm)
22.4
13.5
4.5
–4.5
–13.5
–22.4
–2 s
–2 s
17 Static Posturography and Whiplash
176
posturography on a force platform was carried out in all study participants, by
means of the Romberg test in four sequential phases, using the postural sway area
as a dependent variable. The visual analogue scale (VAS) and Northwick Park
Neck Pain Questionnaire (NPH) were used to evaluate pain and function. Postural
sway area increased signifi cantly in each of the consecutive phases in both groups.
The differences of the means of the postural sway area were statistically signifi cant in all Romberg phases ( p = .009 to p = .000). No correlation was found between
postural sway area and VAS or NPH scores. There was a positive correlation
between the postural sway area standing on a thick foam cushion placed over the
plate with closed eyes and the number of days of transitory incapacity ( r = 0.414;
p = .009).
Two groups of subjects have been studied by Nacci et al. [ 14 ]: Group A
included 90 subjects (age range, 17–73 years; mean age, 40.8 ± 12.6; 59 females
and 31 males) suffering from whiplash injury (Grades 1 and 2 of the whiplashassociated disorders classifi cation – WAD) and Group B comprised 20 subjects
(age range, 23–79 years; mean age, 42.8 ± 17.1; 10 females and 10 males) with
whiplash injury (Grades 1 and 2 of the WAD) associated with minor head injury
(14–15 in the Glasgow Coma Scale – GCS) [41]. All the subjects ( n = 110) in the
study complained of a balance disorder (postural instability, uncertain gait,
vertigo, etc.) that had arisen after trauma. The vestibular-spinal refl ex (VSR) in all
patients was investigated by means of static stabilometry using the S.Ve.P.
Amplifon System © . The stabilometric test (performed within 15 days of trauma,
like the vestibular test) was carried out with eyes open (EO), eyes closed (EC) and
closed eyes with head retrofl exed (CER). To evaluate the role of cervical proprioceptive afferences, the cervical interference index corresponding to the surface
(SCI) and to the length of the oscillations (LCI) was calculated from the percentage ratio between the S and L values when the eyes were closed and the head
retrofl exed and the same parameter when the eyes were closed but the head was
erect, considering a value less than 120 as normal 43.
To eliminate any cases of simulation, stabilometry was performed twice within
the same session in EO, EC and CER (retest) 25. Moreover, to exclude exaggerated
or simulated postural behaviour, subjects who had intercorrelation stabilometric
recordings that appeared frankly sinusoidal and/or those who had over 2,000 mm
surface values in OE were excluded from the study (12 subjects) 25 44. None of the
subjects in Group A ( n = 90) or Group B ( n = 20) showed stabilometric recordings of
sinusoidal intercorrelation in all three tests (OE, CE, CER). As far as the altered
posturographic recordings are concerned, while there was no specifi c pattern in the
two groups, they were clearly pathologic, especially during CER. Both in OE and in
CE, there was an increase in the surface values and in those pertaining to shifting of
the gravity centre on the sagittal plane, which was even more evident during CER.
As far as the indices of cervical interference are concerned in Group A, there was
pathological SCI (n.v. < 120) in 59 cases (59/90; 65.6 %) and pathological LCI
(n.v. < 120) in 44 (44/90; 48.8 %). In Group B, 11 cases with pathological SCI
(11/20; 55 %) and 12 with pathological LCI (12/20; 60 %) were found.
Since vestibular compensation develops after whiplash, the postural performance
improves progressively, even if in certain patients a persistent backward displacement of the pressure centre could be noticed [
15 ]. Often it is only through
P.L. Ghilardi et al.
177
sensitization tests (EC–HST, EC-HER) that it is possible to detect latent static
postural defi ciencies not evident in basic conditions (EO and EC) (Fig.
17.3 ) [ 16 ].
Moreover, the PG allows assessing when some patients have reached a normal
postural performance even retrofl exion. Under these conditions a remarkable
increase in the oscillations on the Y axis and a displacement of the pressure centre
towards the critical side are detected (Fig. 17.4 ) [ 17 ].
–3.0 cm–2.0 cm
–4.3 cm–2.0 cm
–4.3 cm–2.0 cm
Ref.: centre of gravity positionRef.: platform
a
b
c
Statokinesigram
Fig. 17.3 ( a–c ) Patient
suffering from UVL after a
WI with EO ( a ) stabilometry
is normal. Only with
EO-HST ( b ) can an
abnormality of SKG be
detected. With EO-HER ( c )
postural stability shows a
marked worsening
17 Static Posturography and Whiplash