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92
Neuroimaging techniques have failed to report visible structural damage after
whiplash injuries [cf Chap. 6 ]. This has been taken as evidence that whiplash trauma
does not produce signifi cant cerebral lesions. The same may be said for mild brain
injuries [ 22 ]. The cervical trauma resulting from a whiplash injury often coincides
with a signifi cant acceleration-deceleration of or even direct impact to the head,
which can be suspected to produce mild traumatic brain injuries. Furthermore, some
of the symptoms of WAD are similar or identical to those of mild traumatic brain
injuries and post-concussional syndromes. For example, attention defi cits, concentration disturbances, fatigue, and sleep disturbances as well as depression, anxiety,
and pain are common fi ndings [ 23 ]. Diffuse axonal injury produced by shear forces
generated during acceleration-deceleration of the nervous tissue is considered to
constitute the primary pathophysiologic cause of traumatic brain injuries especially
to the parasagittal white matter [ 24 , 25 ].
Decreased attention is a major result of mild traumatic brain injuries and is
also considered to cause concomitant cognitive defi cits [ 26 ]. The decreased
attentiveness may remain for a longer period depending upon the age of the
patient and may not be completely restored even after years. Especially demanding work situations, fatigue, or other disorders may unveil the imperfect recovery. An alternative pathophysiologic mechanism causing central nervous lesions
in whiplash injuries has been suggested by Portnoy [ 27 ] in the monkey and
Svensson in the pig [ 28 ]. During the intense deceleration of the head, there is a
fast and short rise of the intracranial and also intraspinal cerebrospinal fl uid pressure, approaching values as high as 150 mmHg. The authors argue that such a
pressure peak may cause damage to the neural tissue and be responsible for the
concomitant symptoms. Again, the validity of the hypothesis remains to be tested
further.
9.2.3 Vestibular Lesions
Several investigators report a high frequency of abnormal central vestibular signs in
patients with whiplash injuries [ 29 ].
Complaints of dizziness and disorders of balance occur in as many as 23 % of
patients after acceleration injuries to the cervical spine. As clinical examination is
usually normal, the pathological basis for these symptoms is unclear and has variously been attributed to vertebral artery or inner ear or disturbance of the neck righting refl ex induced by paraspinal muscle spasm. Objective evidence of vestibular
involvement has been demonstrated by the correlation of symptoms with electronystagmograms: some patients with dizziness after neck injury show latent nystagmus, abnormal caloric tests, and abnormal rotatory tests.
The acceleration forces could cause signifi cant damage to the delicate middle
and inner ear structures, and faulty inner ear function leads to ineffective muscular
control of balance and erect posture. Perilymph fi stulae requiring surgery were
found in few patients.
M. Magnusson et al.
93
Conclusions
There is no consensus about the pathophysiological mechanisms of whiplash or
WAD. There is no consensus about the pathophysiological mechanism of whip-
lash or WAD. It seems possible that the combination of CNS lesions and soft
tissue or peripheral neural lesions might enhance each other or coincide to pro-
duce the diverse set of symptoms that one might encounter in these patients.
Furthermore, a disturbed attention span may result in different sets of cognitive
impairments, concentration defi cits, and fatigue. Long standing pain may also
trigger psychiatric conditions. WAD per se seems to evoke psychiatric conditions
such as anxiety and depression. Although it is unclear to what extent this is due
to the lesion itself or secondary to other symptoms, these psychiatric impair-
ments may themselves contribute to the distress of the patient.
The possibilities of malingering ones’ symptoms to receive medicolegal ben-
efi ts have not been discussed here.
Improvements in medical imaging techniques may allow better defi nition of
these specifi c injuries and the development of more appropriate treatment.
At the present we have to conclude that we do not have a specifi c unifying
explanation of WAD.
References
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2. Alexander MP (1995) Mild traumatic brain injury: pathophysiology, natural history, and
clinical management. Neurology 45:1253–1260
3. Crowe H (1928) Injuries to the cervical spine. Presentation to the annual meeting of the
Western Orthopedic Association, San Francisco
4. Yadla S, Ratliff JK, Harrop JS (2008) Whiplash: diagnosis, treatment, an associated injuries.
Curr Rev Musculoskelet Med 1(1):65–68
5. Sterling M, McLean SA, Sullivan MJ, Elliott JM (2011) Potential processes involved in the
initiation and maintenance of whiplash-associated disorders. Spine 36:S322–S329
6. Spitzer WO, Skovron ML, Salmi LR, Cassidy ID, Duranceau J, Suissa S, Zeiss E (1995)
Scientifi c monograph of the Quebec Task Force on whiplash-associated disorders. Spine 20
(8 Suppl):1S–73S
7. Johansson H, Bring G, Rauschning W, Sahlstedt B (1991) Hidden cervical spine injuries in
traffi c accident victims with skull fractures. J Spinal Disord 4:251–263
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associated disorders. J Orthop Sports Phys Ther 39(5):312–323
9. Jull GA, Sterling M, Curatolo M, Carroll L, Hodges P (2011) Toward lessening the rate of
transition of acute whiplash to a chronic disorder. Spine 36(25 Suppl):S173–S174
10. Johansson H, Sojka P (1991) Pathophysiological mechanisms involved in genesis and spread
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syndromes: a hypothesis. Med Hypotheses 35:196–203
11. Tencer AF, Huber P, Mirza SK (2003) A comparison of biomechanical mechanisms of
whiplash injury from rear impacts. Annu Proc Assoc Adv Automot Med 47:383–98
12. Johnson G (1996) Hyperextension soft tissue injuries of the cervical spine-review. Emerg Med
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13. Hai-bin C, Yang H, Zheng-guo W (2009) Biomechanics of whiplash injury. Chin J Traumatol
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prognosis. Muscle Nerve 29:768–781
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causalgia. Lancet 2:712–716
17. Jankovic J, Van der Linden C (1988) Dystonia and tremor induced by peripheral trauma: pre-
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273:255–258
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pain patterns. Spine 26:1252–1258
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syndrome. J Clin Exp Neuropsychol 8:32
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M. Magnusson et al.
95
D.C. Alpini et al. (eds.), Whiplash Injuries,
DOI 10.1007/978-88-470-5486-8_10, © Springer-Verlag Italia 2014
Posturology studies disorders of the central nervous system (CNS), thanks to
the categories of space and time. Indeed, at the end of the nineteenth century,
Jean- Marie Charcot and the Salpetriêre’s French school suggested to isolate the
disorders of the CNS that were caused by a lesion—i.e., belonged to a spatial,
anatomic category. That fertile suggestion led to the foundation of neurology.
Jean-Bernard Baron [
1 ] was the fi rst doctor, as far as we know, to observe the
“butterfl y effect” during his experiences (1955) on the regulation of the postural
tonic activity. Butterfl y effect has been described by Lorentz [ 2 ]: “A butterfl y beats
his wings in Brazil and a tornado is released to Texas” to say that the logic of the
postural control systems make a minor modifi cation of one of their parameters that
could bring consequences without proportionality between causes and effects.
Following and continuing those works, many doctors in southern Europe started to
study disorders of the central nervous system whose logical structure is based not
on an anatomical lesion but on the chaotic logic of chained temporal series. Such
studies—particularly vigorous in the fi eld of postural control—constitute
posturology.
The fundamental concept of posturology is the “Fine Postural Control System”
to say that postural control adapts itself to the various behaviors of man: if he is
walking or quiet standing, mechanisms implied in his postural control are not the
same [
3 , 4 ].
P. M. Gagey (*)
Institut de Posturologie , Av. de Corbera 4 , Paris , France
e-mail: pmgagey@club-internet.fr
D. C. Alpini
ENT-Otoneurology Service , IRCCS “Don Carlo Gnocchi” Foundation ,
Milan , Italy
e-mail: dalpini@dongnocchi.it
E. Brunetta
Private Dentist , Conegliano (TV) , Italy
e-mail: elvio.brunetta@fastwebnet.it
1 0
The Contribution of Posturology in Whiplash Injuries
P. M. Gagey , D. C. Alpini , and E. Brunetta
96
Human being, indeed, controls his position in his environment according to a
fundamental operational scheme, common to all behaviors:
• He anticipates his posture according to what he decides to do.
• He controls it by the different inputs of his postural control system.
• He corrects it by muscle activity, either phasic or tonic.
This global scheme may be modulated. Adaptation of postural control to quiet
standing, specifi ed by this behavior, is characterized by:
• A predominance of tonic muscle activity
• A discontinuity of the functioning of some system inputs
• A predominance of feedback loops
Whiplash injuries impact strongly on the “Fine Postural Control System” both
on tonic muscle activity and on sensorial feedbacks. Whiplash leads, in the great
majority of patients, to the so-called disharmonious postural syndrome typically
characterized by the absence of proportionality between the mechanical forces of
the impact and the consequent effects on static and dynamic postural control.
10.1 Disharmonious Postural Syndrome
Clinical theory suggests that altered alignment of the shoulder girdle has the potential to create or sustain symptomatic mechanical dysfunction in the cervical and
thoracic spine. The alignment of the shoulder girdle is described by two clavicle
rotations, i.e., elevation and retraction, and by three scapular rotations, i.e., upward
rotation, internal rotation, and anterior tilt. The search for an abnormal postural
tonic asymmetry forms the basis of the clinical postural examination. This asymmetry at the level of the axial musculature obeys to the laws of spinal movement as
stated by Lowett (1907) (cited by Fryette [ 5 ]):
lateral inclination of the spine of the subject standing up is accompanied by a contralateral
rotation of the lumbar and dorsal vertebrae. This fi nding is easily perceived by gently plac-
ing one’s hands on the patient’s iliac wings and scapulae, while he leans sidewards.
Distal musculature can be explored by means of Fukuda’s stepping test [ 6 ]
followed by measurement of neck refl ex gains [ 7 ].
When the muscle tone is abnormally asymmetrical, we can speak of a “postural
syndrome”: it is said to be “harmonious” when the hypertonicity is crossed between
the axial and distal musculatures; in the opposite case, the postural syndrome is said
to be “disharmonious.” Barré’s “vertical” provides a visual summary of these
postural syndrome analyses (Fig.
10.1 ).
The overwhelming majority of whiplash victims present a disharmonious
postural syndrome; this surprisingly high incidence of disharmonious postural
syndrome following whiplash is statistically signifi cant.
Uemura and Cohen [
8 ] showed that by localized destruction of the vestibular
nuclei in the monkey, it was possible to induce harmonious or disharmonious
postural syndromes depending upon the level of the lesion. However, it is diffi cult
P.M. Gagey et al.
97
to imagine that whiplash systematically produces a lesion of the vestibular nuclei
and even more diffi cult to think that such a lesion would always occur at the same
site. Thus, the meaning of a disharmonious postural syndrome must be sought elsewhere. A clear-cut asymmetry of the electric activity of the neck muscles almost
always exists following whiplash [ 9 ], and this does not seem strange when we
remember the incidence of cervical articulation lesions caused by this type of
trauma. The muscles contract to mitigate the consequences of rupturing ligaments.
The postural importance of these cervical muscles could be showed by stabilometric recordings of these patients: signifi cant asymmetry of the areas of the statokinesigrams appears between the recordings made with the head turned to the right and
then to the left (Fig. 10.2 ).
Helgadottir et al. [ 10 ] confi rmed the postural asymmetry in neck pain and WAD.
Elevation and retraction have been assessed through a three-dimensional device
measured clavicle and scapular orientation, and cervical and thoracic alignment in
patients with insidious onset neck pain (IONP)and whiplash-associated disorder
(WAD). An asymptomatic control group was selected for baseline measurements.
The symptomatic groups revealed a signifi cantly reduced clavicle retraction and
L
R
L
R
Fig. 10.1 Harmonious and
disharmonious postural
syndromes. On the left, in
harmonious syndrome, the
hypertonicity of the axial and
distal muscles is crossed. On
the right, in disharmonious
postural syndrome, the
hypertonicity of the axial and
distal muscles is homolateral
(From Ref. [
7 ] )
10 The Contribution of Posturology in Whiplash Injuries
98
scapular upward rotation as well as decreased cranial angle. A difference was found
between the symptomatic groups on the left side, whereas the WAD group revealed
an increased scapular anterior tilt and the IONP group a decreased clavicle elevation. These changes may be an important mechanism for maintenance and
recurrence or exacerbation of symptoms in patients with neck pain.
Furthermore, whiplash-associated posture modifi cation in the sagittal plane has
been studied by Johansson et al. [ 11 ] that investigated whether a kyphotic deformity
of the cervical spine, as opposed to a straight or a lordotic spine, was associated with
the symptoms at baseline and with the prognosis 1 year following a whiplash injury.
MRI was performed in 171 subjects about 10 days after the accident, and 104 participated in the pain recording at 1-year follow-up. It was demonstrated that postures as seen on MRI can be reliably categorized and that a straight spine is the most
frequent appearance of the cervical spine in supine MRI. In relation to symptoms, it
was seen that a kyphotic deformity was associated with reporting the highest intensities of headache at baseline, but not with an increased risk of long-lasting neck
pain or headache. According to the authors, a kyphotic deformity was not signifi cantly associated with chronic whiplash-associated pain and that pain should not be
ascribed to a straight spine on MRI.
10.2 The Fundamental Oscillation at 0.2 Hz
The ability to maintain balance is diminished in patients suffering from a whiplash
injury. Stabilometry is a widely accepted method to document the impact of
whiplash on static postural control.
Recently Madeleine et al. [ 12 ] investigated the variability of postural control in
patients with chronic whiplash injury analyzing stabilometric recordings from 11
1 cm
1 cm
Left rotation
YY
x
oo
X
Statokinesigram Statokinesigram
Right rotation
Fig. 10.2 Stabilometric recordings with the head turned to the left and the right. On the left, the
subject’s head was turned to the left during the recording session: the area of the statokinesigram
is 2.092 mm
2
. On the right, the subject’s head was rotated to the right during the recording session:
the area of the statokinesigram is 867 mm
2
. The ration of the areas or the cervical quotient is sta-
tistically signifi cant: 2.41 ( p < 0.05)
P.M. Gagey et al.
99
whiplash patients and sex- and age-matched asymptomatic healthy volunteers.
Spatial-temporal changes of the center of pressure displacement were analyzed to
assess the amplitude and structure of postural variability by computing, respectively, the standard deviation/coeffi cient of variation and sample entropy/fractal
dimension of the time series. The amplitude of variability of the center of pressure
was larger among whiplash patients compared with controls ( P < 0.001), while frac-
tal dimension was lower ( P < 0.001). They showed that sample entropy increased
with both eyes closed and a simple dual task compared with eyes open ( P < 0.05).
The analysis of postural control dynamics revealed increased amplitude of postural
variability and decreased signal dimensionality related to the defi cit in postural stability found in whiplash patients.
A specifi c contribution to comprehension of the complex phenomena that subserve postural control is the frequency analysis of the stabilometric signals. Using
the Fourier transform in WAD patients, a fundamental oscillation around 0.2 Hz
(Fig.
10.3 ) is frequently observed. This fundamental oscillation at 0.2 Hz appears
equally on recordings made with the eyes open or closed.
This 0.2 Hz fundamental oscillation must not be confused with the fundamental
oscillation at 0.3 Hz described by Taguchi [ 13 ]. The 0.3 Hz frequency corresponds
to the resonance frequency of the inverted human pendulum that appears during
dysregulations of the fi ne postural control system of which it is sometimes the only
stabilometric witness. This fundamental oscillation simply demonstrates that the
postural system is no longer able to damp out this resonance frequency of the human
pendulum.
The 0.2 Hz fundamental oscillation has a completely different signifi cance.
Patients suffering from rachis pain is characterized by a peak at the frequency of
0
10
20
30
40
60
70
0.15 0.25 0.5 1 1 1.5 2 2.5
50
Attenuation (dB)
Frequencies (Hz)
Fig. 10.3 Fourier’s transform of the stabilometric signals of a whiplash victim. The fundamental
oscillation GI is evident, clearly separated, at a frequency band of about 0.2 Hz (From Ref. [
7 ] )
10 The Contribution of Posturology in Whiplash Injuries
100
0.2 Hz, when the mean power spectrum is compared to a population of normal
subjects [ 7 ]. However, this fundamental oscillation is not pathognomonic of a spine
disorder; it has another origin.
The respiration rhythm is situated in this frequency band of 0.2 Hz; it does not
appear or appears only slightly on the stabilograms of normal standing subjects [ 4 ,
14 ]. Gurfi nkel and Elner [ 15 ] suggest the possibility of a postural adjustment in
preparation of the act of breathing that corrects in advance the postural perturbations resulting from movements of the thoracic cage.
It seems important to emphasize the incidence of the appearance of this respiratory rhythm on the stabilograms of subjects with a spine dysfunction, because Tardy
[ 16 ] showed very close relationships between the static spinal musculature and the
muscles involved in respiration.
Postural control in WAD is disturbed even if subjects are seated as shown by
Cote et al. [ 17 ] that investigated kinematic and electromyographic postural stabili-
zation patterns in individuals with chronic WAD. Ten individuals with WAD and an
age- and gender-matched group of healthy individuals were exposed to sudden
forward and backward support surface translations while they were seated. Neck
and trunk muscle activity and angular displacements as well as centers of mass
(COMs) linear displacements at four levels of the head and trunk were computed.
The displacement onset of the combined head, arms, and trunk COM was signifi cantly delayed in persons with WAD. However, their peak trunk angles were
smaller and were reached sooner. In the WAD group, the activation onset of the
lumbar erector spinae was less affected by perturbation direction, and the sternocleidomastoid muscle, a neck fl exor, showed a trend towards being activated later,
compared to the healthy group. These results suggest that individuals with WAD
may alter stretch refl ex threshold and/or elicit a learned response for pain avoidance
that may be direction specifi c. Such fi ndings highlight the importance of assessing
both spatial and temporal characteristics across different levels of the spinal
musculoskeletal system to evaluate multidirectional postural responses in WAD
individuals.
10.3 Asymmetry of the Activity of the Neck Muscles
Neck muscles are responsible for directing the head and for maintaining its posture.
These functions are accomplished statically and dynamically, using various levels
of contraction, by 22 muscle pairs that connect the head with the cervical spine and
shoulder girdle. Optimal integration of this muscular complex is essential for normal functioning of the head-neck complex, whereas compromising it may result in
associated pain and/or disability. Although assessing neck musculature may be conducted using imaging (ultrasound, computed tomography, magnetic resonance
imaging) and electromyographic studies, from the functional point of view, the relevant parameter(s) refers to the mechanical expression of muscle function which is
invariably refl ected by the ability of neck muscles to develop force (strength) and to
sustain it (endurance).
P.M. Gagey et al.
101
Manual muscle testing (MMT) [ 18 ] could be used for assessing sagittal and
transverse plane strength. Testing is conducted with the patient at the prone (for
extension) and supine (for fl exion and rotation). Strength could be rated according to the MMT scale with grade 3 being equivalent to resisting gravity. Given the
specifi c role of cervical muscles, preserving grade 3 would, in most cases, be
suffi cient for most functional activities since in these test positions the moment
developed by the muscles is already in excess of the strength level required for
normal activities. On the other hand, MMT is of a low validity when strength is
to be rated as grade 4 or 5. Moreover, unlike the frontal plane, where the directional forces—lateral fl exion to the right and to the left—are supposed to be symmetric and, hence, can serve reciprocally for comparison, such is not the case
with fl exion and extension as each depends largely on distinct muscle groups.
Thus, MMT is not a recommended means for assessing cervical strength above
grade 3.
Boquet and Boismare [ 19 ] studied comparatively the electromyograph (EMG) of
the superior heads of the trapezius muscles, left and right. In whiplash victims, they
almost always fi nd marked asymmetry of these EMGs, with the patient’s head in
either the normal position (Fig. 10.4 ) or between positions with the head turned to
the left and to the right (Fig. 10.5 ).
What is most remarkable on the EMG tracings of these patients is not only the
asymmetry but also the amplitude of electrical activity.
Boquet noted signs of increased levels of vigilance, emotionalism, and basic
anxiety in these patients. All whiplash victims do not necessarily have postural
disorders. A supplementary factor is required which Boquet and Boismare link to
this hypervigilance, that is, anxious individuals very often have neck pains and
they blame it on early arthritis, but wrongly so, because one sees people with
arthritis suffi ciently severe to generate cracking sounds without any complain and
contractures, but are calm individuals. This clinical contrast underlines the
Fig. 10.4 Electromyograph ( EMG ) of neck muscles. EMG of the superior heads of the right and
left trapezius muscles of a whiplash victim with his head in the normal position. The asymmetry
of the tracings is obvious (From Ref. [
7 ] )
10 The Contribution of Posturology in Whiplash Injuries