A.G. Remnev
NEW POSSIBILITIES OF USING MAGNETIC STIMULATION IN THE EVALUATION OF
FUNCTIONAL CONDITION OF ARC OF BLINK REFLEX
Altai diagnostic centre, Barnaul, Russia
E-mail: rag@ctmed.altai.ru
Introduction
At present many physicians: neurologists, neurosurgeons, stomatologists, oculists and other show
a big interest in studying an blink reflex. This interest is caused by known difficulties of
diagnostics of striking the nervious conductors on the face, difficulties of therapy different
pathological conditions, accordanced with striking of facial or trigeminal nerves. That is why
exact instrumental diagnostic of striking the different arcs areas of blink reflex is important.
The blink reflex is hold at the reflex arc, afferent by the section which is a first branch of
trigeminal nerve, and efferent - a facial nerve (Kugelberg, 1952). Diagnostics and treatment of
diseases of facial and trigeminal nerves is one of the most important problems of modern medical
science. This is explained first of all that, when striking a facial nerve not less than in 25%
recovery turns out to be incomplete or does not approach at all. Asymmetry of face, impossibility
to close an eyelid on the smitten side, lacrimation from the eye, nerve-racking pains in the smitten
half of face - incomplete suffering list sick with pathology trigeminal-facial complex. All these
factors obstruct a social adaptation of sick this pathology and bring often to inconvertible change
on the face.
At present blink reflex study has get a broad spreading in the clinic for the diagnostics of
striking trigeminal and facial nerves (Lindquist and Martenson, 1970; Elek et al., 1988). Defeat as
trigeminal, so and facial nerves is characterize by increase latency registerred components of
blink reflex or their absence (Kimura et al., 1969). Modern need of clinic require more exact
determination of striking level, since differential diagnostics of breaking trigeminal nerve and
facial nerve clinical can be labored.
Proposed decision. Method transcranial magnetic stimulation (TMS) can be perspective in
deciding this problem. This method is used in the diagnostics of diseases of nervous system from
1985, when scientists of The Sheffield University for the first time was created magnetic
facilitator, capabled to cause excitement a motor cortex of cerebrum of face (Barker et al., 1985).
Method TMS has found a broad using in the clinical practice at the study of undertaking
excitement on pyramidal ways under different forms of striking a central nervous system (Barker
et al., 1985; Wassermann et al., 1991). Using a method TMS opens inaccessible previously
possibility of testing a function of some cranial nerves (Maccabee et al., 1988ab; Berardelli et al.,
1991ab; Rimpilainen et al., 1991; Rimpilainen et al., 1992). However, at present complex study
of functional condition of arc of blink reflex with the help of TMS and electrical stimulation was
not conduct.
Methods and materials
In our laboratory was designed original way of differential diagnostics of functional condition of
trigeminal nerve, facial nerve and cerebronuclear ways of facial nerve. Realization of this way
consists of several steps.
Step 1: Originally blink reflex researched under the electrical stimulation (ES) superciliary
nerve on side of abduction of caused answer. Registerring (conduct) electrodes we located so:
active electrode was install on the circular muscle of eye, referent - on the skin of face, in
projections an zygomatic bone from two sides of face on the right and on the left. Except
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registerring electrodes we installed a shallow electrode of earth on the wrist of patient. During the
study gave square-wave pulses of electrical current, following on the right rhythm with the
repetition rate 2-3 Hz, duration 0,1 ms, amperage - 15-35 mA at sensitivity 100 mkV. Under ES
registerred a curved blink reflex, consist of two components - early respons (R1) and late respons
(R2). We valued latency these components, which measured from the artifact of irritating to the
peak of negative phase of answer.
Step 2: We realized TMS in projections a motor cortex of cerebrum. The magnetic field
depends on the type of coil connected. At the study used 90 mm coil (coil surface 2,0 T max.,
pulse characteristics - 100 ms approximate rise time, 1 ms duration). For registrations blink reflex
was sufficiently magnetic pulse 30 - 50% from the maximum output power of magnetic
facilitator. For each sides was registerred 3-4 answers for determination the shortest latency. We
located registerring (conduct) electrodes in spots, as at blink reflex study under ES. Under TMS
we registerred a curved blink reflex, consist of two components - early (R1) and late (R2). We
valued latency these components, which we measured from the artifact of irritating to the peak of
negative phase of answer. TMS we realized with the help of the magnetic stimulator Мagstim200 (Magstim Company Limited, UK). Caused answers we registerred with the help of
electromyograph Sapphire Premiere (Medelec Limited, UK).
Step 3: We realized a test of results, received under ES and TMS. On the Fig. 1 is present
general scheme of blink reflex study under two types stimulations. From the Fig. 1 is seen that
under TMS and ES on side of abduction of caused answer an undertaking excitation is realized on
the nucleus and filaments of facial nerve. Consequently, nucleus and filament of facial nerve are
general area for undertaking excitation (on the Fig. 1 is marked by the length ВС). However,
undertaking excitation to the nucleus of facial nerve under ES and TMS is realized by different
ways. Under ES excitation of nucleus of facial nerve occurs by means of the transmission of
excitation on the first branch and nucleuses of trigeminal nerve, under TMS - by means of
cerebronuclear ways of facial nerve (on the Fig. 1 is marked by the length АВ).
Fig.1. Scheme evaluation of functional condition of arc of blink reflex under ES and TMS.
Note. 1 - superciliary area; 2 - trigeminal nerve; 3 (B) - nucleus nervi facialis; 4 - facial nerve; 5
(C) - musculis orbicularis oculi; 6 (A) - motor cortex of cerebrum; 7 - cerebronuclear ways of
facial nerve.
Breach of undertaking excitation on the nucleus and filaments of facial nerve will be
characterized by change latency components of blink reflex under TMS and ES. Breach of
undertaking excitation on cerebronuclear ways of facial nerve will be characterized by increase
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latency components of blink reflex only under TMS on the background satisfactory latency these
components under ES. Breach of undertaking excitation on trigeminal nerve system will be
characterized by increase latency components of blink reflex under only ES on the background
satisfactory latency components of blink reflex under TMS.
Results
We examined 128 sick with striking the different arc divisions of blink reflex: 46 sick with
striking an trigeminal nerve (neuropathy) different origin at an age from 24 to 49 years (first
group), 52 sick with striking (neuropathy) facial nerve different origin at an age from 18 to 57
years (second group), 30 sick multiple sclerosis (cerebrospinal form) at an age from 22 to 38
years (third group). Group of checking consisted of 37 healthy people faces at an age from 18 to
33 years.
Sick first group study. Sicks with the denominated classical picture neuropathy of
trigeminal nerve were realized ES and TMS by described way. Typical blink reflex are submit for
the Fig. 2.
Fig. 2. Blink reflex under ES (1,2) and TMS (3,4) on the right (1,3) and on the left (2,4) beside
patient with striking trigeminal nerve.
Note. Axis of abscissas - a time, price of doing – 5ms (1,2), 10 ms (3,4); axis of ordinates - an
amplitude, price of doing – 1mV.
From the Fig. 2 is seen that under ES was registered caused answer, consist of two
components – R1 and R2. Latency R1 on the right was 13,3 ms, on the left was 15,8 ms, latency
R2 on the right was 32,0 ms, on the left was 28,7 ms. Latency R1 was increased on 19,0% on the
left in contrast with similar to factors, received beside healthy people (Table 1).
Table 1. Latency of components of blink reflex beside healthy people and sick people under ES
Patients
R1, ms (М±m)
R2, ms (М±m)
Side
Side
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Healthy people
12,9±0,2
12,9±02
34,3±0,6
35,1±0,7
on the right
on the left
on the right
on the left
Sick with defeat
13,1±0,2
15,8±0,5*
35,3±1,0
37,4±1,1
TN
healthy side
sick side
healthy side
sick side
Sick with defeat
13,0±0,1
17,7±0,4*
24,5±0,6
37,8±1,0
FN
healthy side
sick side
healthy side
sick side
Sick with defeat
13,1±0,2
13,2±0,2
36,5±1,0
36,9±1,1
CWFN
on the right
on the left
on the right
on the left
Note. M - Arithmetic mean; m - standard mistake; TN - trigeminal nerve (5th cranial nerve); FN facial nerve (7th cranial nerve); CWFN - cerebronuclear ways of facial nerve; asterisk differences between healthy people and smitten sides reliable (P<0,01).
This indicative of that, this had a two-way breach of undertaking excitation on the arc of
blink reflex. However, define more exactly, where is localized damage in this instance, is not
possible. Because of that, striking, as trigeminal nerve, and as facial nerve brings increase latency
R1 (Lindquist and Martenson, 1970).
Under TMS was registered caused answer, consist of two components – R1 and R2 (Fig.
2) in this patient. R1 had latency on the right 14,8 ms, on the left – 15,4 ms and R2 had latency on
the right 36,1 ms, on the left – 34,7 ms. Under recurrent TMS in same area, latency, form and
caused answer amplitude were sufficiently firm. Factors latency components of caused answer
complied with similar to factors, received beside healthy people (Table 2). Consequently,
undertaking excitation on cerebronuclear ways of facial nerve, filaments and nucleus of facial
nerve beside this patient was satisfactory.
Table 2. Latency of components of blink reflex beside healthy people and sick people under TMS
Patients
R1, ms(М±m)
R2, ms (М±m)
Side
Side
Healthy people
14,7±0,2
14,8±0,2
34,8±0,8
34,5±0,8
on the right
on the left
on the right
on the left
Sick with defeat
15,1±0,7
15,0±0,7
36,2±0,8
36,4±1,0
TN
on the right
on the left
on the right
on the left
Sick with defeat
14,7±0,2
23,1±0,8*
36,7±0,8
44,9±1,8*
FN
healthy side
sick side
healthy side
sick side
Sick with defeat
15,3±0,6
28,3±1,7*
35,6±1,1
45,9±2,3*
CWFN
healthy side
sick side
healthy side
sick side
Note. M - Arithmetic mean; m - standard mistake; TN - trigeminal nerve (5th cranial nerve); FN facial nerve (7th cranial nerve); CWFN - cerebronuclear ways of facial nerve; asterisk differences between healthy people and smitten sides reliable (P<0,01).
Comparing results, received under ES and TMS possible note that beside the under
investigation patient on the background of satisfactory undertaking excitation on cerebronuclear
ways of facial nerve, filaments and nucleus of facial nerve (on results TMS) had been a breach of
undertaking excitation on filaments of trigeminal nerve, its node and nucleus, and on the nucleus
in the same way and filaments of facial nerve on the left and on the right (on results ES). Thereby,
we have get signs of breaking an undertaking of excitement on the system of trigeminal nerve on
the left beside this patient.
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We researched a group by the sicks with neuralgia of trigeminal nerve. Responses to ES
and TMS were presented in all subjects. Results of studies are presented in Tables 1 and 2. From
results, present in this Tables is seen that change latency components of blink reflex was
registered only under ES (increase latency R1). Thereby, complex blink reflex study under ES
and TMS allows differently value a functional condition of trigeminal nerve system, reveal and
quantitatively value a degree of striking an trigeminal nerve.
Sick second group study. Sicks with striking a facial nerve different origin realized a
complex blink reflex study under ES and TMS by described way. Typical components of blink
reflex received beside the patient under two types an stimulation are submit for the Fig. 3.
Fig. 3. Blink reflex under ES (1,2) and TMS (3,4) on the right (1,3) and on the left (2,4) beside
patient with striking facial nerve.
Note. Axis of abscissas - a time, price of doing – 5ms (1,2), 10 ms (3,4); axis of ordinates - an
amplitude, price of doing – 800mkV.
From the Fig. 3 is seen that under ES was registered caused answer, consist of two
components – R1 and R2. Latency R1 on the right was 17,0 ms, on the left was 13,5 ms, latency
R2 on the right was 35,5 ms, on the left was 31,8 ms. By comparing these factors with similar,
received beside the healthy people, was rendered that latency R1 was on the right increased on
30,8%. This indicatived of that, beside patient a breach of undertaking excitation on the arc of
blink reflex was on the right. However, after undertaking ES was not possible to define more
exactly, where the damage, was localised, since defeat, as trigeminal nerve, and as facial nerves
brings for increase latency R1 on the side of defeat.
Under TMS was registered caused answer, consist of two components – R1 and R2 in this
patient (Fig. 3). R1 had latency on the right 29,7 ms, on the left - 15,1 ms, R2 had latency on the
right 36,6 ms, on the left - 38,3 ms. Latency R2 complied with similar, received beside healthy
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people (Table 2). Latency R1 was increased on 96,7% on the right in contrast with the left side.
This was indicative of that, a breach of undertaking excitation on cerebronuclear ways of facial
nerve, filaments and nucleus of facial nerve was beside this patient on the right. However, to
install more exactly striking localization at results solely TMS was not presented possible.
Comparing results, received under ES and TMS it is possible note that beside the under
investigation patient on the background of breaking an undertaking of excitation on
cerebronuclear ways of facial nerve, filaments and nucleus of facial nerve (on results TMS) was a
breach of undertaking excitation on filaments of trigeminal nerve to its node and nucleus, but on
the nucleus in the same way and filaments of facial nerve on the right (on results ES).
Consequently, available breach was caused by striking right facial nerve.
At the study of group of patients with striking a facial nerve different origin results were
similar. Beside patients with striking a facial nerve on the side of striking we registered increase
latency R1 under ES and increase latency R1 under TMS. Beside 19 sicks of second group
(36,5%) under ES and TMS components of blink reflex were not registered.
Thereby, increase latency R1 blink reflex under ES and in the same way increase latency
R1 under TMS is characteristic of breaking an undertaking of excitation on the facial nerve.
Sick third group study. For the reason determinations of involvement in the pathological
process under multiple sclerosis of conduct ways of arc of blink reflex for, sicks with
cerebrospinal by the form of multiple sclerosis we realized ES and TMS by described way.
Typical curved caused answers are on the Fig. 4.
Fig. 4. Blink reflex under ES (1,2) and TMS (3,4) on the right (1,3) and on the left (2,4) beside
patient with multiple sclerosis.
Note. Axis of abscissas - a time, price of doing – 5ms (1,2), 10 ms (3,4); axis of ordinates - an
amplitude, price of doing – 1mV.
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From the Fig. 4 is seen that ES was characterized by presence R1 and R2. Latency R1 On
the right was 12,8 ms, on the left - 13,1 ms, latency R2 on the right was 40,4 ms, on the left - 39,4
ms. Beside this patient under TMS is received caused answer consist of components R1 and R2.
R1 had latency on the right 32,9 ms, on the left - 29,3 ms, R2 had latency on the right 50,1 ms,
on the left - 53,7 ms. Under recurrent TMS in same area, latency, form and caused answer
amplitude were sufficiently firm. Latency R2 complied with similar factors, received beside
healthy people. Latency R1 Was increased on 125,3% on the right and on 96,6% on the left.
Comparing results, received under ES and TMS it is possible note that beside the under
investigation patient, on the background of breaking an undertaking of excitation on
cerebronuclear ways of facial nerve and filaments and nucleus of facial nerve on the right and on
the left (on results TMS), undertaking excitation on filaments of trigeminal nerve, its node and
nucleus, and on the nucleus in the same way and filaments of facial nerve was satisfactory (on
results ES). Consequently, this breach was caused by striking cerebronuclear ways of facial nerve
on the right and on the left.
We researched a group of sicks with multiple sclerosis. Responses to ES and TMS were
present in all subjects. All sicks this group did not present complaints on the breach the functions
of muscles of face. So smitten side considered that side, at the study which latency components of
blink reflex exceeded similar factors, received beside the clinical healthy people. Render that
beside 22 sicks third group (73,3%) was registered increase latency R1 under TMS (Table 2),
from them beside 12 sick (40,0%) – two-way. Herewith latency components of blink reflex under
ES was not changed.
Thereby, increase latency components of blink reflex under TMS, registered beside sick
multiple sclerosis indicates of breaking an undertaking of excitation on cerebronuclear ways of
facial nerve.
Conclusion
We recorded the conduct test of complex diagnostics of blink reflex study under ES and TMS
beside sicks with striking the different arc areas of blink reflex (Fig. 5).
TN
FN
TMS
ES
CWFN
0
50
100
150
200
Fig. 5. Procentage correlation an latency R1 under ES and TMS beside sick with striking an arc of
blink reflex on the different level.
Note. On axis of abscissas - a procentage correlation an latency R1 with respect to similar to
factors beside the healthy people; for 100% are accepted factors an latency in the rate; TN trigeminal nerve (5th cranial nerve); FN - facial nerve (7th cranial nerve); CWFN -
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cerebronuclear ways of facial nerve; TMS - transcranial magnetic stimulation; ES - electric
stimulation.
From the Fig. 5 is seen that beside sick with striking a trigeminal nerve registerred an
increase an latency R1 only under ES. Under striking a facial nerve registerred an increase a
latency components of blink reflex under both types a stimulation. When striking cerebronuclear
ways of facial nerve registerred an increase an latency components of blink reflex only under
TMS.
Thereby, complex using ES and TMS beside sick allows objectively differentiate a
striking an trigeminal nerve, facial nerve and cerebronuclear ways of facial nerve.
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