A study of motor nerve conduction in correlation with lower limb deformities
and locomotor performance in children with meningomyelocele
Ocena przewodnictwa nerwowego we włóknach ruchowych w korelacji z deformacjami
kończyn dolnych i lokomocją u dzieci z przepukliną oponowo-rdzeniową
Krzysztof Sendrowski, Leszek Boćkowski, Wojciech Sobaniec, Bożena Okurowska-Zawada, Piotr Sobaniec
Department of Pediatric Neurology and Rehabilitation, Medical University of Białystok, Poland
STRESZCZENIE
Przepuklina oponowo-rdzeniowa (POR) jest często występują-cym zaburzeniem rozwojowym zamknięcia kanału kręgowego, powstałym we wczesnym okresie tworzenia się u płodu struktur rdzenia kręgowego i kręgosłupa. Wadzie towarzyszy zniesienie lub osłabienie przewodzenia bodźców nerwowych od struktur centralnych układu nerwowego do mięśni, skóry i narządów wewnętrznych, co manifestuje się m.in. niedowładami wiotkimi kończyn, zwłaszcza dolnych. Następstwem POR są deformacje stawów kończyn oraz współistniejące zaburzenia lokomocji. Ocena charakteru i stopnia nasilenia tych zaburzeń opiera się na klasycznym badaniu neurologicznym. Jako dodatkowy element diagnostyczny wykorzystuje się badania elektrofizjologiczne.
Celem pracy była analiza wyników badania
elektroneurogra-ficznego (ENG) w korelacji z deformacjami kończyn dolnych oraz osiągniętą lokomocją u dzieci z POR. Materiał i metoda. Badania przeprowadzono u 61 pacjentów (31 chłopców i 30 dziewcząt) z POR w wieku 1-17 lat (średnia 7+4,4 lat) przy użyciu 4-kanałowego aparatu MEDELEC Sapphire Premiere. Oceniano amplitudę odpowiedzi M oraz maksymalną prędkość przewodzenia przy obustronnej stymulacji nerwu strzałkowego wspólnego i nerwu piszczelowego. Wyniki. U 90% badanych dzieci stwierdzono uszkodzenie badanych nerwów obwodo-wych o charakterze aksonalnym, z czego aż u 40% pacjentów nie uzyskano odpowiedzi elektrofizjologicznej. Wykazano, że u dzieci z prawidłowymi wartościami przewodzenia nerwowego deformacje kostno-stawowe kończyn dolnych (szczególnie stawu biodrowego i kolana) są 3-4 krotnie rzadsze w porów-naniu z tymi bez odpowiedzi elektrofizjologicznej. Tylko 20% pacjentów z POR, u których nie uzyskano odpowiedzi elektro-fizjologicznej, chodzi samodzielnie, podczas gdy u pacjentów z widoczną odpowiedzią, nawet przy jej nieprawidłowych war-tościach – aż 80% z nich.
Słowa kluczowe: przepuklina oponowo-rdzeniowa,
elektro-neurografia, dzieci
ABSTRACT
Meningomyelocele (MMC) is a common developmental abnor-mality in which the vertebral canal formed during fetal develop-ment of the spine and the spinal cord fails to close. The defect is accompanied by abolition or attenuation of conduction of nerve stimuli from central structures of the nervous system to muscles, skin and internal organs, which is manifested, among others, in flaccid paresis of the limbs, especially in the lower limbs. MMC leads to joint deformities and locomotor dysfunc-tion. Assessment of the nature and severity of these disorders is based on the classical neurological examination. Addition-ally, electrophysiological investigation is also performed as a diagnostic component. The aim of paper. The study objective was to assess the results of electroneurographic examination (ENG) in correlation with lower limb deformities and ultimate locomotor performance in children with MMC. Material and
methods. The study involved 61 patients (31 boys and 30 girls)
with MMC, aged 1-17 years (mean 7+ 4.4 years), using a four-channel MEDELEC Sapphire Premiere machine. We evaluated the M response amplitude and the maximum conduction veloc-ity, with bilateral stimulation of the common peroneal nerve and tibial nerve. Results. Peripheral nerve damage (axonal injury) was found in 90% of the study children and 40% of these chil-dren showed no electrophysiological response. Chilchil-dren having normal nerve conduction values were found to be at a three- to four-fold lower risk of osteoarticular deformities (especially of the hip and knee) in comparison with patients showing no electrophysiological response. Only 20% of the MMC patients without electrophysiological response were be able to walk effi-ciently, as compared to 80% of those with a distinct response, even when abnormal.
Key words: meningomyelocele, electroneurography, children
Me���gomyelocele �MMC� �s a co�ge���al defec� �� wh�ch �he pr�mary �eural �ube fa�ls �o close �� �he early embryo��c per�od [1,2]. Malforma��o�s mos� freque��ly affec� �he sp��al segme�� of �he �eural �ube, more seldom ��s cerebral par�
[3,4]. D�sorders of �he �ervous sys�em coex�s� w��h defec�s of �he cra��um, �he sp��e a�d �he�r �egume��s. The v�s�ble dysraph�c les�o�s are freque��ly accompa��ed by sp��al a�d cerebral defec�s �� d�s�a�� s��es, wh�ch may cause
add���o-�al compl�ca��o�s a�d u�favorable prog�os�s [5]. Tak��g ���o accou�� ��s ��c�de�ce �1:1000 l�ve b�r�hs�, MMC �s �he seco�d mos� commo� co�ge���al d�sorder [6], affec���g �he sp��al cord a�d sp��al �erves wh�ch ar�se a� �h�s level, cere-brosp��al me���ges, ver�ebrae, muscles, subcu�a�eous ��ssue a�d sk��. The d�sorder �s accompa��ed by abol���o� or a��e-�ua��o� of �erve s��mulus co�duc��o� from ce��ral s�ruc�ures o��o �he body per�phery �o muscles, sk�� a�d ���er�al orga�s. MMC �s a �o�-s�ab�l��ed defec�. �rogress�o� of locomo�or dysfu�c��o� �s due �o body grow�h. New pareses or paralyses a�d se�sory def�c��s are caused by ex�e�s�o� of �he sp��al cord a�d �erve roo�s as a resul� of adhes�o� of �erve ele-me��s �o �he surrou�d��gs. O�her fac�ors affec���g �he �eu-rolog�cal co�d���o� may ��clude sp��al �schem�a, ��fec��o� or MMC closure surgery. The bo�y clef� d�me�s�o� hardly ever correspo�ds �o �he ex�e�s�o� of �eurosegme�� damage. The ex�e�s�o� of paralys�s �s �he resul� of pr�mary dysplas�a of �he sp��al cord a�d ��s roo�s, seco�dary ab�ormal���es a�d coex�s���g developme��al defec�s. The cl���cal p�c�ure of locomo�or d�s�urba�ces a�d of �he or�g��a���g deform���es of �he lower ex�rem���es depe�ds o� �he level of �eurosegme�� ��jury a�d �ype of paralys�s. The mos� commo� os�eoar��-cular deform���es �� ch�ldre� w��h MMC ��clude dysplas��c h�ps, co��rac�ures of k�ee jo��� a�d foo� deform���es �usually equ��e foo� a�d equ��ovarus foo� �� h�gh MMC loca��o�; cal-ca�eus foo� a�d hollow foo� �� low MMC loca��o��. These �umerous deform���es have a �ega��ve effec� o� �he b�ome-cha��cs of �he foo�, �he k�ee or �he h�p, reduc��g, some��mes comple�ely, �he locomo�or po�e���al of �he ch�ld [7, 8].
Early a�d �horough d�ag�os��c assessme�� of �he �euro-log�cal co�d���o� �� ch�ld w��h MMC �spo��a�eous mob�-l��y of �he ex�rem���es, muscle �o�e, phys�olog�cal reflexes, sph��c�er fu�c��o�� �s �ecessary for es�abl�sh��g �he me�hods of early locomo�or rehab�l��a��o�. The assessme�� of �he respec��ve groups of muscles �ha� are fu�c��o�ally �mpor-�a�� �s esse���al dur��g �he f�rs� exam��mpor-�a��o� of a ch�ld w��h MMC [9]. The exam��a��o� should co��a�� eleme��s of roo� ���erva��o� assessme�� �� order �o def��e �he level of sp��al damage, des�g� a� accura�e rehab�l��a��o� schedule a�d �o predict the child’s ultimate locomotor performance.
Curre��ly, �he class�cal �eurolog�cal exam��a��o� �s freque��ly suppleme��ed w��h some accessory d�ag�os��c �ools �ha� could �mprove mak��g prog�os�s of �he fu�ure cl���cal co�d���o� of pa��e��s w��h MMC a�d, above all, def��e �he cha�ces for locomo�or au�o�omy of �he affec-�ed ch�ld. Apar� from a w�de ra�ge of �euro�mag��g ��ve-s��ga��o�s �U�G, CT, MRI�, elec�rophys�olog�cal �es�s are freque��ly performed �� ch�ldre� w��h
MMC
. Somatosen-sory evoked po�e���als a�d elec�romyography have bee� mos� commo�ly used ��ves��ga��o�s [10-13], elec�ro�eu-rograph�c exam��a��o�s be��g �he leas� commo�. Howe-ver, co��rary �o soma�ose�sory evoked po�e���als wh�ch �s ��me-co�sum��g a�d �ech��cally d�ff�cul� �� small ch�l-dre� a�d u�l�ke elec�romyography wh�ch �s ��vas�ve a�d pa��ful, elec�ro�eurography �s qu�ck, �o���vas�ve a�d does �o� requ�re pa��e��’s coopera��o�. The elec�ro�eurograph�c ��ves��ga��o� allows de�erm��a��o� of co�duc��o� veloc��y �� �he per�pheral �erves a�d prov�des da�a co�cer���g �he �a�ure �axo�al or demyel��a���g� a�d ex�e�s�o� ofpo�e�-��al damage �o �he per�pheral �erves. The co�duc��o� velo-c��y reflec�s �he ac��v��y of �erve f�bers show��g �he h�ghes� co�duc��v��y. The ampl��ude of �he �erve ac��o� po�e���al ��d�ca�es �he �umber of co�duc���g axo�s [14].Desp��e �he adva��ages of �he elec�ro�eurograph�c exam��a��o�, �h�s �ool has bee� ex�remely rarely used for �he d�ag�o-sis of children with
MMC
, as show� by l��era�ure survey. Hav��g �h�s �� m��d, we dec�ded �o u�der�ake �he curre�� s�udy.OBJECTIVE
The a�m of �he curre�� s�udy was �o prac��cally assess �he useful�ess of elec�ro�eurograph�c exam��a��o� �� es�abl�s-h��g prog�os�s of lower l�mb deform���es a�d locomo�or potential in children with
MMC
. Elec�ro�eurograph�c exa-m��a��o� was performed �o objec��vely de�erm��e �he degree of lower l�mb �erve damage. The correla��o�s of �he resul�s of elec�rophys�olog�cal exam��a��o�s w��h ch�ld’s lower l�mb deform���es a�d �he ach�eved locomo�or performa�ce were evalua�ed.pATIENTS AND METHODS
The s�udy a�alys�s ��volved 61 ch�ldre� w��h
MMC
, �rea�ed �� �he Depar�me�� of �ed�a�r�c Neurology a�d Rehab�l��a��o� a�d ��s Ou�pa��e�� Depar�me��, U��vers��y Ch�ldre�’s Hosp�-�al �� �Hosp�-�alys�ok �� �he years 1990-2005. There were 31 boys a�d 30 g�rls, aged 1-17 years �mea� 7+ 4.4 years�. �ased o� �he med�cal h�s�ory, fu�c��o�al assessme�� a�d evalua-��o� of �he muscle s�re�g�h, �he ch�ldre� were d�v�ded ���o groups depe�d��g o� �he level of �he preserved �euroseg-me��s accord��g �o �he �harrad’s co�cep� [15]: �he �horac�c level, �he lumbar level a�d �he sacral level. The�, �he cl���cal p�c�ure was a�aly�ed �� correla��o� w��h �he elec�ro�euro-graph�c exam��a��o�. The mos� �umerous group �38; 62%� co�s�s�ed of ch�ldre� w��h lumbar MMC, �hose w��h �horac�c loca��o� were less �umerous �17; 28%�. �acral loca��o� was fou�d �� 6 pa��e��s �10%�. I� 58 �95%�, ope� MMC was observed.Elec�ro�eurograph�c �es� was performed us��g a four-cha��el MEDELEC �apph�re �rem�ere mach��e �� agre-eme�� w��h �he ge�erally accep�ed �ech��que w��h body surface �empera�ure measureme�� [16]. The follow��g co�-duction parameters in motor fibers of the common pero-�eal �erve a�d ��b�al �erve were assessed: max�mum mo�or �erve co�duc��o� veloc��y a�d �he M-respo�se ampl��ude. Each pa��e�� u�derwe�� mo�or �erve co�duc��o� �es���g in the standard manner with the use of surface electrodes. Recep��o� elec�rodes were placed above m. extensor digi-torum communis and m. abductor hallucis longus, to assess �he commo� pero�eal �erve a�d ��b�al �erve, respec��vely. The ��b�al �erve was s��mula�ed beh��d �he med�al malleous a�d �� �he popl��eal fossa; �he pero�eal �erve was s��mula-�ed o� �he a��er�or surface of �he lower leg jus� a� �he a�kle a�d beh��d �he head of �he pero�eal bo�e. The f��d��gs were compared �o age appropr�a�e �orma��ve values ��he labora�ory’s ow� s�a�dards�.
The E�h�cs Comm���ee of Med�cal U��vers��y of ��ały-s�ok approved all procedures �� �h�s s�udy. The s�a��s��cal
a�alys�s was performed by mea�s of �he follow��g �es�s: ch�-square ��depe�de�ce �es�, var�a�ce a�alys�s �es�, �-��u-de�� �es� for ��depe��-��u-de�� samples, � �es� for a s��gle sample, ch�-square co�s�s�e�cy �es�. The p<0.05 was co�s�dered s�a��s��cally s�g��f�ca��.
RESULTS
Conduction velocity. I� �he s�udy group, s��mula��o� of �he pero�eal �erves d�sclosed slowed co�duc��o� veloc��y �� 16-20% of cases. Normal co�duc��o� veloc��y values were recorded �� 38-43%, a�d approx�ma�ely 40% of �he �erves were u�respo�s�ve. W��h s��mula��o� of �he ��b�al �erves, co�duc��o� veloc��y was slowed �� 25-28% of cases, �ormal �� 30%, a�d �o respo�se was recorded �� approx�ma�ely 40%. Resul�s are prese��ed �� Table I.
The M-response amplitude. �ero�eal �erve s��mula-��o� resul�ed �� lowered ampl��ude �� 49-54% of cases. The
M-respo�se ampl��udes were �ormal �� o�ly 2-8% a�d 39-44% of �he �erves were u�respo�s�ve. W��h ��b�al �erve s��mula��o�, lowered ampl��udes were recorded �� approx�-ma�ely 50% of cases, be��g �ormal o�ly �� 8-13%. Appro-x�ma�ely 40% of �he �erves were u�respo�s�ve. Resul�s are prese��ed �� Table II.
ELECTRONEUROGRApHY pARAMETERS IN CORRELATION WITH THE CLINICAL pICTURE Of LOWER-LIMB JOINT DEfORMITIES
Conduction velocity and lower-limb joint defor-mities. Tables III a a�d III b prese�� �he freque�cy of �he observed cl���cal ab�ormal���es �� correla��o� w��h co�-duc��o� veloc��y �� �he per�pheral �erves exam��ed �e.g. �o�a��o� 21/26 mea�s �ha� amo�g 26 pa��e��s w��hou� elec-�rophys�olog�cal respo�se �� �he lef� l�mb as ma�y as 21 ch�ldre� had a dysplas��c h�p�.
Table I. The number of nerves with conduction velocity values as compared to the norms. MNCV – maximum nerve conduction velocity; LPN – left peroneal nerve; RPN – right peroneal nerve; LTN – left tibial nerve; RTN – right tibial nerve
MNCV N LPN % N RPN % N LTN % N RTN %
Slowed 12 20 10 16 17 28 15 25
Normal 23 38 26 43 20 33 21 34
Lack of conduction 26 42 25 41 24 39 25 41
Total 61 100 61 100 61 100 61 100
Table II. The number of nerves with the M-response amplitudes as compared to the norms. AMP – M-response amplitude; LPN – left peroneal nerve; RPN – right peroneal nerve; LTN –left tibial nerve; RTN – right tibial nerve
AMP N LPN % N RPN % N LTN % N RTn %
Lowered 33 54 32 49 30 53 31 51
Normal 1 2 5 8 8 13 5 8
No response 27 44 24 39 23 38 25 41
Total 61 100 61 100 61 100 61 100
Table IIIa. Motor nerve conduction velocity (MNCV) in the peroneal nerves in correlation with lower limb joint deformities. Lack of response – no conduction velocity value was obtained, no voluntary or reflex muscular activity was observed in the lower limbs
CLINICAL PICTURE OF LOWER LIMB JOINTS
MNCV FOR PERONEAL NERVE
Left limb Right limb
lack of
response slowed down normal responseLack of slowed down normal
Dysplastic hip 21/26 81% 6/12 50% 5/23 22% 15/25 60% 3/10 30% 4/26 15%
Knee contracture 25/26 96% 7/12 58% 8/23 35% 19/25 76% 19/10 20% 9/26 35%
Equinovarus foot 26/26 100% 12/12 100% 14/23 61% 24/25 96% 7/10 70% 15/26 58% Table IIIb. Motor nerve conduction velocity (MNCV) in the tibial nerves in correlation with lower limb joint deformities
CLINICAL PICTURE OF LOWER LIMB JOINTS
MNCV FOR TIBIAL NERVE
Left limb Right limb
Lack of
response Slowed down Normal responseLack of Slowed down Normal
Dysplastic hip 19/24 79% 9/17 53% 4/20 20% 15/25 60% 3/15 20% 4/21 19%
Knee contracture 23/24 96% 1/17 65% 6/20 30% 20/25 80% 3/15 20% 7/21 33%
The amplitude of M potential in correlation with lower limb joint deformities. Tables IV a a�d IV b pre-se�� �he freque�cy of cl���cal ab�ormal���es depe�d��g o� the amplitude of M potential.
Table V prese��s �he overall l�s� of �es� resul�s for all comparisons.
The overall l�s� of ch�-square �es� resul�s for compar�so�s �for each l�mb� def����ely shows a s�a��s��cally s�g��f�ca�� correla��o� of �he cl���cal p�c�ure w��h mo�or �erve co�-duc��o� veloc��y a�d �he ampl��ude of M po�e���al. Lower l�mb jo��� dysfu�c��o�s are fou�d amo�g �he pa��e��s w��h �o elec�rophys�olog�cal respo�se evoked or w��h ab�ormal values of co�duc��o� veloc��y a�d M po�e���al ampl��ude from �he per�pheral �erves, a�d are much more commo�
�ha� �� pa��e��s show��g �ormal elec�rophys�olog�cal para-me�ers. Th�s ��d�ca�es �ha� elec�ro�eurograph�c exam��a-��o� ca� be used �o de�erm��e �he degree of damage �o �he �ervous sys�em, assess �he curre�� s�a�e of �he mo�or orga� a�d �o make prog�os�s of
MMC
complications.ELECTRONEUROGRApHY pARAMETERS IN CORRELATION WITH ULTIMATE LOCOMOTOR pERfORMANCE
The correla��o� be�wee� �he ul��ma�e locomo��o� a�d elec-�ro�eurography parame�ers �s prese��ed �� Table VI.
As �he da�a are almos� �de���cal for all �he �erves s�u-d�ed, here �hey are show� o�ly for �he lef� pero�eal �erve. O�ly pa��e��s over �he age of 7 years were co�s�dered Table IVa. The amplitude of M potential for the peroneal nerve in correlation with lower-limb joint deformities
CLINICAL PICTURE OF LOWER LIMB JOINTS
AMPLITUdE FOR PERONEAL NERVE
Left limb Right limb
Lack of response Lowered Normal responseLack of Lowered Normal
Dysplastic hip 22/27 81% 10/33 30% 0/1 0% 15/24 63% 6/32 9% 1/5 20%
Knee contracture 26/27 96% 14/33 42% 0/1 0% 19/24 79% 11/32 4% 0/5 0%
Equinovarus foot 27/27 100% 25/33 6% 0/1 0% 23/24 96% 20/32 3% 3/5 60%
Table IVb. The amplitude of M potential for the tibial nerve in correlation with lower-limb joint deformities
CLINICAL PICTURE OF LOWER LIMB JOINTS
AMPLITUdE FOR TIBIAL NERVE
Left limb Right limb
Lack of
response Lowered Normal responseLack of Lowered Normal
Dysplastic hip 19/23 83% 12/30 40% 1/8 13% 15/25 60% 6/31 19% 1/5 20%
Knee contracture 22/23 96% 14/30 47% 4/8 50% 20/25 80% 9/31 29% 1/5 20%
Calcaneus foot 23/23 100% 23/30 77% 6/8 75% 24/25 96% 18/31 18% 4/5 80%
Table V. The overall list of test results for all comparisons
THE COMPAREd FEATURES Left limbCHI-SQUARE TEST OF Independence RESULTS (P)Right limb
CV (pn) | Dysplastic hip 0.0002 0.0037
CV (pn) | Knee contracture 0.0000 0.0017
CV (pn) | Foot deformity 0.0002 0.0059
CV (pn) | The overall 0.0007 0.0020
AMP (pn) | Dysplastic hip 0.0002 0.0025
AMP (pn) | Knee contracture 0.0000 0.0003
AMP (pn) | Foot deformity 0.0017 0.0116
AMP (pn) | The overall 0.0059 0.0012
CV (tn) | Dysplastic hip 0.0005 0.0052
CV (tn) | Knee contracture 0.0000 0.0002
CV (tn) | Foot deformity 0.0187 0.0028
CV (tn) | The overall 0.0022 0.0004
AMP (tn) | Dysplastic hip 0.0005 0.0052
AMP (tn) | Knee contracture 0.0006 0.0003
AMP (tn) | Foot deformity 0.0407 0.0045
AMP (tn) | The overall 0.0023 0.0019
�assum��g �ha� �he ga�� process �s �erm��a�ed arou�d �he age of 7�.
Ultimate locomotion in correlation with conduction velocity. As ma�y as 12 �71%� ch�ldre� w��h �ormal co�-duc��o� veloc��y a�d o�ly 2 pa��e��s w��h �o respo�se acqu�red ga�� eff�c�e�cy. O�ly o�e ch�ld w��h �ormal co�-duc��o� veloc��y a�d as ma�y as 20 �80%� pa��e��s who d�d �o� respo�d �o �erve s��mula��o� use a wheelcha�r as �he ma�� mea�s of locomo��o�. O�e ch�ld w��h �o respo�se, 4 pa��e��s w��h co�duc��o� veloc��y slow��g a�d as ma�y as 9 w��h �ormal values acqu�red l�m��ed ga�� �o�ly w��h�� �he apar�me���. Ver��cal��a��o� by mea�s of a ver��cal�-���g equ�pme�� was ob�a��ed o�ly �� 2 pa��e��s w��h �o response.
Ultimate locomotion in correlation with M-potential amplitude. Twe��y of �he pa��e��s with no M response use o�ly a wheelcha�r a�d o�ly 3 ca� walk eff�c�e��ly. Of �he ch�ldre� w��h lowered ampl��ude of M-po�e���al, 14 acqu�-red ga�� eff�c�e�cy a�d 12 could walk o�ly w��h�� �he apar�-me��. The correla��o� be�wee� �he locomo�or performa�ce acqu�red a�d elec�ro�eurography resul�s �s s�a��s��cally s�g-nificant.
DISCUSSION
Children with MMC constitute a difficult therapeutic prob-lem due �o co��rac�ures a�d ��s�ab�l���es of �he jo���s, as well as because of �mpa�red developme�� a�d grow�h of �he l�mbs. These usually adva�ce w��h �he ch�ld’s grow�h a�d affec� �he locomo�or po�e���al. I� �he s�udy group, we obser-ved fu�c��o�al a�d �he� s�ruc�ural co��rac�ures of �he h�ps, bo�h symme�r�cal a�d asymme�r�cal. D�sloca��o� of o�e h�p jo��� usually occurred whe� �he abduc�or muscles were para-ly�ed a�d �he adduc�or muscles ac��ve. L�kew�se, flex�o� co��rac�ures of �he k�ees var�ed �� sever��y a�d �� evolu��o� of f�xa��o� def�c��. The progress�o� of �he k�ee co��rac�u-res was assoc�a�ed w��h �he degree of paco��rac�u-res�s of �he quadr�-ceps muscle of �he �h�gh accompa��ed by �he ac��ve flexor muscles of �he k�ee. The �eurolog�cal symp�oms depe�ded o� �he level of damage �o �he sp��e a�d sp��al cord. I� should be remembered �ha� mos� caudal, s��ll fully eff�c�e�� segme�� of �he sp��al cord de�erm��es �he level of paralys�s [15].
I� �he s�udy pa��e��s w��h h�gh-level sp��al cord damage, hip joints had to be treated with ortosis or distractor in 82%, whereas �� �hose w��h low-level damage �� 64%. H�p dysplas�a �� h�gh-level damage occurred �� 64-50% of
�he ch�ldre�. Flex�o� co��rac�ure �� �he k�ee predom��a-�ed �� �he h�gh
MMC
loca��o� �ype a�d was observed �� 66-77%, as compared �o �he low-level �ype �� 45-58% of cases. The resul�s are comparable w��h �hose ob�a��ed by Ma�ur e� al [8].As revealed by our curre�� f��d��gs a�d da�a repor�ed by o�her au�hors, foo� deform���es are a very �mpor�a�� a�d common clinical issue in children with
MMC [8,17].
As show� by �ar�o�ek e� al. [18], lower l�mb jo��� deform���es a�d ga�� dysfu�c��o� depe�d o� spas��c��y a�d �mbala�ce of �he muscular sys�em of �he a�kle, �he k�ee a�d �he h�p. Therefore, �� was �ecessary �o perform �� each ch�ld a co�-���uous dy�am�c exam��a��o� w��h accura�e observa��o� of moveme��s.Elec�ro�eurograph�c ��ves��ga��o� of �he per�pheral �erves �s compleme��ary �o �he �eurolog�cal exam��a��o�. �oćkowsk� e� al. [19] have emphas��ed �ha� �he level of damage fou�d dur��g �he de�erm��a��o� of muscle s�re�g�h a�d �eurolog�cal exam��a��o� ca� be ver�f�ed by �he elec-�ro�eurograph�c ��ves��ga��o�. O�her au�hors [12,20,21] sugges� �ha� �he elec�rophys�olog�cal exam��a��o�s per-formed �� ��fa��s before a�d af�er surg�cal procedure ca� fac�l��a�e prog�os�s of �he degree of mo�or �mpa�rme��, whereas �� older ch�ldre� �he elec�romyograph�c ac��v��y of chose� muscle groups dur��g walk��g ca� be used �� �he assessment of orthopedic equipment.
I� our s�udy, �he s��mula��o� of �he pero�eal a�d ��b�al �erves resul�ed �� �o elec�rophys�olog�cal respo�se �� approx�ma�ely 40% of pa��e��s. Mos� of �hese ch�ldre� had a dysplas��c h�p a�d flex�o� co��rac�ures of �he k�ees �76-96%�, a�d all of �hem had equ��ovarus foo� a�d calca�eus foo�. Amo�g �he ch�ldre� w��h �ormal co�duc��o� veloc��y �approx�ma�ely 30-40%�, �he perce��age of �hose w��h equ��ovarus foo� a�d calca�eus foo� was markedly lower �52-70%�. Deform���es �� pa��e��s w��h �ormal co�duc��o� veloc��y �� bo�h �erves ca� be assoc�a�ed w��h prolo�ged u�co��rolled ly��g or s�����g pos���o�. Our curre�� resul�s are co�s�s�e�� w��h �he f��d��gs ob�a��ed prev�ously �� our ce��er [19] as well as w��h da�a repor�ed by ��ulc a�d Gło-wack� [22]. The elec�ro�eurograph�c exam��a��o� showed s�g��f�ca�� d�ffere�ces �� mo�or co�duc��o� veloc��y a�d a s�g��f�ca�� reduc��o� �� �he M-respo�se ampl��ude �� �he pero�eal a�d ��b�al �erves as compared �o age appropr�a�e norms. We also confirmed our earlier results of studies co�duc�ed o� a smaller group of pa��e��s [19], wh�ch ��d�-Table VI. ENG parameters in correlation with ultimate locomotor performance (independent mobility)
ULTIMATE EFFECT
OF INdEPENdENT MOBILITY
Motor conduction velocity M-potential Amplitude Lack of
response Slowed down Normal responseLack of Lowered Normal
N % N % N % N % N % N %
Efficient gait 2 12 3 18 12 71 3 18 14 82 0 0
Limited walk
/only within the apartment/ 1 7 4 29 9 64 1 7 12 86 1 7
Verticalization
/only verticalizing equipment/ 2 100 0 0 0 0 2 100 0 0 0 0
Only wheelchair 20 80 4 16 1 4 20 80 5 20 0 0
ca�ed a correla��o� be�wee� �he degree of dysfu�c��o�s �� elec�rophys�olog�cal exam��a��o�s a�d �he sever��y of such complications as contractures and deformities of lower l�mb jo���s. The defec�s were more pro�ou�ced �� �he group of ch�ldre� w��h a �horac�c loca��o� of MMC, less �� ch�l-dre� w��h �he sacral �ype. Thus, we should emphas��e �he useful�ess of �he elec�ro�eurograph�c exam��a��o�s for �he prog�os��ca��o� of deform���es w��h�� �he lower l�mbs �� �he course of MMC, eve� whe� �hey are s��ll �� a la�e�� form. �are��s mos� freque��ly ask abou� �he cha�ce for �he�r ch�ld �o walk ��depe�de��ly. The locomo�or po�e���al �� MMC ch�ldre� depe�ds, above all, o� �he level of �eurosegme�� damage, be��g �he h�ghes� whe� �he damage �s “low”. The a�alys�s of correla��o�s be�wee� ul��ma�e locomo��o� a�d elec�ro�eurograph�c exam��a��o�s showed �ha� as ma�y as 80% of pa��e��s w��hou� elec�rophys�olog�cal respo�se o� �he s��mula��o� of �he pero�eal a�d ��b�al �erves have �o use a wheelcha�r as compared �o over 70% of pa��e��s w��h �ormal co�duc��o� who ach�eved ga�� eff�c�e�cy. The elec�ro�eurograph�c exam��a��o�s revealed �� mos� cases ex�e�s�ve axo�al dege�era��o� w��h�� �he per�pheral �erve �ru�ks of �he lower l�mbs, wh�ch correla�ed w��h MMC loca��o�. ���ce �he exam��a��o� �s l���le ��vas�ve a�d does �o� requ�re pa��e��’s co-opera��o�, us��g �he appropr�a�e surface electrode technique we can predict remote sequels
of �he defec� from �he earl�es� mo��hs of l�fe. Th�s allows ��s���u��o� of eleme��s of preve���o� espec�ally �� ch�ldre� w��h �he �horac�c a�d �horacolumbar damage. The resul�s of �he �europhys�olog�cal exam��a��o�s ca� be used by a phys�o�herap�s� �o des�g� a rehab�l��a��o� schedule.
CONCLUSIONS
1. I� �he s�udy group of ch�ldre� w��h MMC subjec�ed �o s��mula��o� of �he per�pheral mo�or �erve f�bers of �he lower l�mbs, approx�ma�ely 40% showed �o elec�rophys�o-log�cal respo�se. I� over 50% of ch�ldre�, �he M-respo�se ampl��ude was markedly lowered. O�ly fewer �ha� 10% of �he s�udy ch�ldre� had �ormal elec�ro�eurography parame-�ers. These da�a co�f�rm damage �o mo�or �erve f�bers �� �he lower l�mbs �ma��ly axo�al�, �� over 90% of �he s�udy children.
2. I� ch�ldre� w��h �ormal values of �erve co�duc��o� os�eoar��cular deform���es of �he lower l�mbs �espec�ally �� �he h�p a�d k�ee jo���s� are 3-4 fold lower, as compared �o �he ch�ldre� w��h �o elec�rophys�olog�cal respo�se.
3. O�ly every f�f�h ch�ld show��g �o elec�rophys�olo-g�cal respo�se w�ll be able �o walk ��depe�de��ly, whe-reas as ma�y as 80% of pa��e��s w��h elec�rophys�olog�cal respo�se, eve� whe� ab�ormal, have such a cha�ce.
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Correspondence:
Krzysztof Sendrowski, Department of Pediatric Neurology and Rehabilitation, Medical University of Białystok 17 Waszyngtona Street, 15-274 Białystok