CC BY
27
UDC 616-073.7:616-072.7
M.A.ALIYEV12, A.S. ZHAYLAUBAYEVA2, DB MUSTAFINOV1, V.S.KARAVAYEV1, B.M.AGLAKOV2, G.Y. SULEIMENOV
1 Kazakh Medical University of Continuing Education, Almaty
2 City Clinical Hospital No.7, Almaty, Kazakhstan
INTRAOPERATIVE NEUROMONITORING IN SPINAL NEUROSURGERY AT ALMATY CITY CLINICAL HOSPITAL № 7
SUMMARY
Intraoperative neuromonitoring represents an opportunity to observe the state of the the nervous system structures during surgical intervention and to define, reduce and prevent neurological deficits prior to the surgery. Intraoperative neuromonitoring remains important, as the surgeon has no neuronavigation information during the operation to remove tumors/ Moreover, constantly changing structures can reduce the quality of the manipulations performed. Therefore, the neurophysiologist who also participates during the operations on the spinal cord "co-work" with the neurosurgeon closely in order to establish the physiological limits of resection, to prevent mechanical damage to the spinal cord and its ganglia: overstretch, rupture, trauma, detection of damage to the vessels in proper time and thereby preventing potential iatrogenic lesions.
41 operations were performed using Nim Eclipse intraoperative neuromonitoring by Medtronic at the Almaty City Clinical Hospital No. 7, This article describes neuromonitoring methods and good results confirming an obtained effectiveness. A total intravenous anesthesia without myorelaxants was performed according to the international standards of anesthesiologists. A close interaction of neurophysiologists, neurosurgeons, anesthesiologists is required in order to improve postoperative results and reduce the risks of neurologic lesions:
Key words: intraoperative neuromonitoring, somatosensory evoked potentials, motor evoked potentials, trigger electromyography, spinal neurosurgery.
Reducing the frequency of intraoperative complications is one of the topical issues of modern neurosurgery. Modern neurosurgical technical equipment helps to prevent and detect abnormalities of the nervous system during the operation, to predict potential complications. Intraoperative neuromonitoring (hereinafter referred to as "IONM") allows real-time evaluation of the integrity of structures at different levels of the National Assembly. This is the gold standard for operations in various areas of the spine: with degenerative diseases, with deformities, removal of spinal cord tumors or trauma complication.
In this article, we performed an analysis of modern representations and possibilities of IONM use according to the literature as well as we took our own data taken during spinal surgical interventions at the City Clinical Hospital No. 7 in Almaty.
The purpose of the study: to study results obtained from applying intraoperative neuromonitoring in the last three years during the spinal cord operations at the City Clinical Hospital No. 7 in Almaty.
Material and methods: since October 2014, the use of IONM on the Nim Eclipse device of Medtronic (USA) was introduced at the City Clinical Hospital No. 7. This allowed recording of all necessary neurophysiological parameters for various types of operations.
The choice of exact IONM modalities was made by a neurophysiologist, according to the protocol of preoperative access planning as well as with consideration of the scope of surgical intervention done by the neurosurgeon.
Given the sensitivity of the conduct of the IONM, the anesthetic aid did not use long-acting muscle relaxants, the main stage of anesthesia was maintained on a combination of propofol with fentanyl. According to the international standards of The LAFS (Los Angeles Anesthesia Friendliness Scale) for anesthesiology, patients undergoing IONM undergo total intravenous anesthesia without the use of muscle relaxants.
According to the analysis of the results, 41 surgical interventions with the use of IONM were performed. In particular, installation of stabilizing structures in degen-erative-dystrophic changes of the spinal column was as follows - 13; removal of extra- and intramedullary neoplasms - 28 in total. The age of patients varied from 18 to 77 years. Each patient before the operation performed neurophysiological monitoring, analysis of the patient's neurological status, MRI data, and then on intraoperative monitoring regimes with an individual approach in each case. The choice of the modality of IONM in operations on the spinal cord was caused by potentials and myography. Continuous monitoring of the conductivity of the spinal cord, spinal roots and peripheral nerves was performed.
A peripheral receptors response from SSEP (somatosensory evoked potentials) stimulated by electrical impulse was obtained by excitation of the brain sensory cortex (Figure 1). Reducing the amplitude and increasing the latency of the SSVP by 50% was an alarm signal for damage to the structures of the spinal cord. In our case, there was no significant reduction in the indices. Rhythmic
stimulation of the SSEP was carried out from each point the initial values and then continuously until the necessary alternately to the main stage of the operation to determine manipulations were completed.
Figure 1. Somatosensory evoked potentials with excitation of the sensory cortex of the brain
MEP (motor evoked potentials) in the patients was performed to assess the state of the motor conducting pathways of the spinal cord with the stimulation of the motor cortex by an electrical impulse. To register TkMVP, spinal scalp electrodes were administered subcutaneously at points C3, C4 according to the extended international system "10-20%". The registering needle electrodes were established depending on the level of spinal cord lesion on the target muscles of the upper (m. Deltoideus, M. biceps / triceps brachii, m.tenor, m. abductor hallucis and m. abductor pollicis brevis.) and lower limb (m quadriceps / biceps femoris, m gastrocnemius, m. tibialis anterior), with lumbosacral lesions also on the anal sphincter. Earthing electrodes were injected into intact muscles. After the introduction of electrodes prior to the beginning of the study, in all cases the impedance was checked to verify the correctness of their installation. Reducing the amplitude by 50% and increasing the latency by 10% are the main indicators of the violation in the entire motor chain. Also, it should be noted that factors that significantly affect SSEP: inhalation anesthetics, temperature, blood pressure were also monitored.
Figure 2. Visible appearance of motor evoked potentials.
Figure 3. Stages of a persistent fixation.
Direct stimulation by electric impulse or direct mechanical action.
The advantage of the motor response in peripheral stimulation is that it comes with less latency (faster) than with the registration of profit centers. Registration is performed between two needle electrodes mounted on the target muscles, depending on the level of damage. A neurosurgeon using a bipolar or a monopolar probe can accurately determine the roots of the spinal cord and assess the correct location of the screw in the body of the vertebra according to international visualization standards developed by neurophysiologists (Figure 3). If the implanted screw was completely positioned in the bone, it was further
shielded and the electrical stimulation of the screw does not activate the nerve. But if the medial wall of the vertebral body was damaged, a conductor with low resistance between the screw and surrounding tissues is formed. And when the current was applied to the screw, the nerve root was stimulated, the corresponding muscles contracted, and the MVP was recorded.
In this case, a stimulating bipolar and (or) monopolar electrode was used, the current strength was from 7 to 15 mA (Figure 4). Trigger EMG was also used to assess the correct position of transpedicular screws when installing stabilizing structures. In this case, the stimulus strength was 3-5 mA, the duration was 200 ms.
Figure 4. Using a monopolar electrode.
The parameters of registration and stimulation of intraoperative neurophysiological neuromonitoring were performed according to international standards, reflected in Table 1.
Table 1. Registration and stimulation parameters.
Parameter ДЕР EMG/CMAP TESMEP TES HEP DC МЕР DC МЕР SEP SEP EEG VEP
transcranial O-Wave motoric Speech M. media nus N.tibialis
Filter
Hardware High-pass filter (fu) 16D 3o 30 30 30 30 30 30 0.5 0.5
Software Hiqh-pass fills r (lull 05 05 0.5 05 0.5 0.5 0.5/30..... 0.5/30..... 0.5 0.5
Software Low-pass filter (to} [1 3500 2000 2000 3500 2000 2000 600 600 70 100
Gain (mVpp) 1 100 100 100 100 100 10 10 10 10
Number of Averages 1000 1 1 ..5 100 (50 .. 300) 150 (50 . 300) 100
Stimulation
Duration cont. cont. foot switch 1 cont. cont. тад. 4 sec. max. 3 sec cont.' cont.4 cont.
Stimiiation frequency [Hz] n s, ie.2 3,30 0.5-2, ISI4 ms 1-2 D.M ISI 4 ms 50 4.7 3.7 1.1
Pulse form click, suction rectanqle Irain, 4-6 pulses biphasic Irain, 4 pulses pulse, biph. rectanqle pos. rectanqle pos. LED flash
Intensity 90. 95"dB 0,05.45..5«A 40.. 220 mA, 40..220 mA supra max 4. ,30 mA 4.. 20 mA 3.. 30mA"" Э..45 mA'" 15mA
Pulse width [ml 200 500 1000 500 500 200 - 500 200-500 750,11500—
Max. Vulta«B [VI 100 300 300 80 60 100 160 120
OisplayfAnalyse
Time scale [ms] 20 200 par div 130 20 130 50 100 500
Amplitude scale ||jV1 (B^Aver1 20/0,Э1 500 300 30 300 2t>№5 20/36 100 200/5
Sweep duration [ms] 20 130 30 130 BO 130 500
Latencies (Peaks) III. V. Ill-V 3-15ms N20. P25 P40 P100
Figure 5. Removal of intramedullary tumor.
Figure 6. Removal of intramedullary tumor on the monitor.
Results of the study and their discussion:
During intraoperative neuromonitoring, minor changes in bioelectrical indices were noted, all stages of operative intervention were performed according to preoperative planning. During the operation, correction of the surgeon's manipulation was performed with:
1) a stable decrease in the amplitude of evoked potentials below the baseline by 50%, an increase in latency of 10% (compulsory comparison of data with anesthesia, hypothermia, arterial pressure);
2) a stable M-response with stimulation of a transpedic-ular screw with a current strength of 3-4 mA (oscillations of SSVP and TcMVP up to 30% were considered acceptable). In the case of irritation of motor fibers, M-responses to EMG were obtained, disappearing after the termination of the manipulation. In 5 patients with degenerative-dys-trophic changes of the spine, the amplitude of the SSVP was below 0.9 mV during the entire intraoperative period (while maintaining normal latency). Motor disorders of the conductor type developed in one case after surgery for the removal of intramedullary tumors with complete regression during 10-15 days of conservative therapy.
According to the literature, there are reports of false positive and false negative results of neuromonitoring, on average. These data represented approximately 4%, the
most frequent causes of which are anesthesia, temperature in the operating room and blood pressure indicators. [14].
IONM is an additional effective method of intraoperative diagnostics, which allows to reduce the risks of postoperative complications and improve the results of surgical manipulations.
Conclusions: Intraoperative neuromonitoring:
1. allows to monitor the functional consistency of motor portions of the conducting pathways of the spinal cord, peripheral structures, and helps to reduce the degree of motor and sensory disorders during the operation.
2. helps to find the safest access when removing intramedullary spinal cord tumors and reduces the risk of postoperative neurologic disorders;
3. Ensures control and prevention of intraoperative complications with predicting the course of the postoperative period;
4. Identifies the anatomical structures within the operating field and contributes to an increase in the radical nature of the operative intervention and the safely of the submerged metal-fixed spinal column without the formation of iatrogenic neurological deficits;
5. It is needed for the legal security of the operating surgeon due to the formation of the neurophysiological protocol and its application to the medical documentation.
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ТУЙ1НД1
Интраоперациялык нейромониторинг - бул оперативт1 араласу кезшде бастапк,ы жумыс ¡стеушен K,ayirm ауытк,уларды дер кезшде анык,тау ушш жуйке жуйеа к,урылымдарыныц жагдайына уздказ ба^ылау жасау. Соцгы онжылдык,та к,ол жетмзшген нейронавигациялык, эд!стемелердеп прогреске к,арамастан, интраоперациялык нейромониторинг мацыздыльиын сак,тайды, ейткен1 кебшесе нейронавигациялык аппарат к,аутаз ¡актерд1 жою ушш жеткмнказ болады; сонымен к,атар, операция кезшде нейронавигация дэлдПн азайтатын ми ^урылымдарын ыгыстыруы мумкш.
Жулын операциялары кезшде нейрофизиологтьщ Heri3ri мшдел резекцияныц физиологиялык, шекарасын белплеу, жулын мен оныц Ty6ipmeriHin меха ни калы к, зак,ымдануыныц алдын алу: а рты к, созылуы, жыртылуы, жарак,ат, жулынныц к,оректенуш зак,ымдайтын тамырлардыц зацымдануын уак,ытында табу.
Алматыцаласыныцк,алалык,ауруханасы №7Мес11гоп1сфирмасыныцМ1тЕс11р5еинтраоперациялык1нейромониторинг1н пайдалана отырып, 41 ота жасалды. Ма^алада зерттеу журпзу эд1стер1 жэне, эд1стщ тшмдшП туралы статистикалык, деректерд1 растайтын алынган нэтижелер усынылган. Нейромониторинг сэтп болуы ушш нейрофизиологтардыц нейрохирург жэне анестезиологтармен ундескен езара ¡с-к,имылы болуы.
Кшт сездер: интраоперациялы^ нейромониторинг, соматикалык^-сенсорлыцтан туындаган элеует, моторлы туындаран элеует, триггерл1 электромиография, жулын нейрохирургиясы.
АННОТАЦИЯ
Интраоперационный нейромониторинг - это возможность наблюдать за состоянием структур нервной системы во время оперативного вмешательства, обнаруживать, уменьшать и предотвращать неврологический дефицит от исходных значений до операции. Интраоперационный нейромониторинг сохраняет актуальность, так как хирургу не хватает нейронавигационной информации во время операции по удалению новообразований и постоянно изменяющиеся структуры могут снизить качество проводимых манипуляций.
Задача нейрофизиолога при операциях на спинном мозге - работа с нейрохирургом в тесном контакте, установление физиологических границ резекции, предотвращение механического повреждения спинного мозга и его корешков: перерастяжения, разрыва, травмы, своевременное обнаружение повреждения сосудов, питающих спинной мозг и тем самым снижение ятрогенных повреждений.
В городской клинической больнице №7 г. Алматы проведена 41 операция с использованием интраоперационного нейромониторинга Nim Eclipse фирмы Medtronic. В работе показаны методы проведения нейромониторинга и получены хорошие результаты подтверждающие эффективность. Проводится тотальная внутривенная анестезия без миео-релаксантов согласно международным стандартам анестезиологов. Для улучшения результатов послеоперационного периода и снижения рисков неврологических поражений необходимо постоянное взаимодействие всех специалистов: нейрофизиологов, нейрохирургов, анестезиологов.
Ключевые слова: интраоперационный нейромониторинг, соматосенсорные вызванные потенциалы, моторные вызванные потенциалы, триггерная электромиография, спинальная нейрохирургия.
