Comparative Study of Complex Spina Bifida and Split Cord Malformation Raj Kumar, S.N. Singh, K.K. Bansal and Vinita Singh 1

Department of Neurosurgery & INeuroanestheliology, 5anjay Gandhi Post Graduate Institute of Medical Sciences & King George's Medical University, Lucknow, India.

Abstract. Obiectiva: To see the difference in clinical profiles, radiological findings and surgical outcome of the group 1 split cord malformation and meningomyelocele (SCM with MMC) from group 2 (SCM without MMC). Methods: 46 patients of SCM were selected from a total of 138 cases of spinal dysraphism. They were divided into two groups, based on presence or absence of MMC. Group I (SCM with MMC) n =19 patients and Group II (SCM without MMC) n=27 patients. A detail clinical evaluation and MR screening of whole spine of all cases was performed. All patients underwent surgical detethering of cord. After an average follow-up of 1.7 years, the operative results were clinically assessed and statistical significance was calculated. Results: Male to female ratio was1:09. Mean age of presentation was 3.6 years. Cutaneous markers like tuft of hair, cutaneous haemangioma, etc, had a higher incidence in group II in comparison to group I (50% vs 10.5%). The incidence of motor deficits was significantin group I in comparison to group II (63% vs 40%). The incidences of sensory loss, trophic ulcers, sphincteric dysfunction and muscle atrophy were relatively more common in group I patients, while neuro-orthopedic deformities such as congenital telepes equinovarus (CTEV), scoliosis and limb shortening were more frequent (67%) in group II children as compared to group I (53%). Type I SCM has higher incidence in group I children. Low lying conus were found in 47% patient of group I, while in group II it was noticed in 69%. The associated cranial anomalies like hydrocephalus, ACM and syrinx, were slightly higher in group I patients. At surgery, dysgenetic nerve roots, neural placode, arachnoid bands and atrophic cord were seen mainly in group I. Postoperative complications like, CSF leak, pseudomeningocele and meningitis were more commonly encountered in group I patients. The patients of group II showed better operative outcome compared to group I cases. Conclusion : Incidence of SCM with MMC amount to 41% of total SCM cases. Progressive neurological deficit was higher in this group (SCM with MMC) in comparison to the group harboring SCM without MMC. In view of a significant association of SCM in MMC cases, associated with other craniospinal anomalies, a thorough screening of neuraxis (by MRI) is recommended to treat all treatable anomalies simultaneously for desired outcome. [Indian J Pediatr 2005; 72 (2) : 109-115] E-mail : rajkumar@sgpgi.ac.in

Key words : Split cord malformation; Complex spina bifida; Spinal dysraphism.

Split Cord Malformat ion (SCM) is the most common under ly ing anatomical abnormal i ty of occult spinal dys raph i sm. 1.2 U n d e r s t a n d i n g of the spl i t cord malformation has become better after the paper of Pang in 1992. 3.4 SCM may present with MMC (complex spina bifida) s or without MMC as an occult anomaly? ,6 SCM commonly presents with various cutaneous markers like hairy patch, subcutaneous lipoma, cutaneous capillary hemangioma and uncommonly with meningomyelocele sacY Children with SCM may not have any neurological deficit at the time of birth but deficits may appear with growth of the chi ld, a t t r i bu ted to spinal cord te ther ing . 3 Once neurological deficits have occurred, often they do not improve completely even after detethering. -~ MMC is a cr ippl ing condi t ion manifest ing with mild to severe neurological deficit and usually with less number of

Correspondence and Reprint requests : Dr. Raj Kumar, Associate Professor, Department of Neurosurgery, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow-2260]4, U.E, India. Fax: 91(522) 268129, 2668017

cutaneous markers other than overt MMC sac. Hence, the clinical spectrum of SCM and MMC is relatively different. With the advent of MRI, the diagnosis of SCM has become relatively frequent. MRI not only deciphers the precise anatomy but also helps in detecting the associated lesions. Though, SCM has been var iab ly descr ibed in recent l i terature, present ly very scarce material is available regarding the problem of SCM, when it is associated with meningomyelocele.

Present study was carried out to compare the clinical profiles, radiological findings and surgical outcome of pat ients having SCM with MMC (Group I) and SCM without MMC (Group II).

MATERIALS AND METHODS

Forty six patients of SCM were selected and analyzed from a total of 138 cases of spinal dysraphism, studied p r o s p e c t i v e l y and r e t ro spec t i ve ly (126/12) , in the N e u r o s u r g e r y d e p a r t m e n t of Sanjay Gandh i Post Graduate Institute of Medical Sciences, Lucknow, India

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between June 1989 and June 2001. The s tudy was carried out to compare the clinical profiles, radiological findings and surgical outcome of the patients having SCM with MMC and occult SCM alone. Forty six cases were divided into two groups, based on presence or absence of MMC; Group I (SCM with MMC) n=19 patients and Group II pure occult SCM (SCM without MMC) n=27 patients. Male to female ratio was 1" 09. Mean age of presentation was 3.6 years for all cases (range 2 days to 14 years). A detailed clinical examination of each case was recorded. Eight patients were referred with plain X-ray spine (6 of group I and 2 of group II). One patient of group I came with plain CT of spine. Spinal MRI was performed in all 46 cases, where entire spine was screened. However , cranio-spinal MRI could be possible in 27 pat ients on account of financial reasons. SCM was classified into type I and Type II depending on the presence of bony spur or fibrous sep tum respectively. This typing was based on radiological and operative findings (Fig. 1 and 2). All the pat ients u n d e r w e n t surgical excision of bony s p u r / fibrous septum, and repair of MMC depending on the type of anoma ly . Pos tope ra t ive ly the pa t i en t s were examined on 7 ~ day and then followed up periodically at 1~ months, 3 and 6 months interval. After an average fol low-up of 1.7 years (range 6 weeks to 6 years), the operative results were clinically assessed.

CLINICAL FINDINGS

Bar diagram I to 5 and Table 1, 2 show comparison of the incidence of c u t a n e o u s marke r s , n e u r o - o r t h o p e d i c syndromes, associated anomalies, clinical profiles and outcome in both group I and II.

GROUP I (SCM WITH MMC)

Group I compr i s ed of 19 chi ldren hav ing congeni ta l meningomyelocele, or lipomeningomyelocele along with SCM. Fifteen children of this group presented with overt meningomyelocele, where MRI showed underlying split cord malformation. Progressive sensory and motor deficit was found in 9 and 12 cases respect ive ly . Out of 12

Fig. 1.'/~R'i-axial cut'showing two asymmetricai hemicords separated by fibrocollagenous septum (SCM type I). Relatively distal myelomeningocele sac is also evident at the same level.

Fig. 2. Intra-operative photograph showing two asymmetrical cords following excision of intervening bony spur (cords separated by forcep). Distal myelomeningocele is excised, not visible in the print.

TABLE 1. Showing Statistical Significance of Clinical Presenta- tions in Group I and Group II

S1. Clinical Group I Group II Fisher's No. presentation n = 19 n = 27 exact test

(5%) p value

1. Motor Weakness 12 11 0.016 2. Sensory loss 09 10 0.013 3. Trophic Ulcer 03 01 0.561 4. Autoamputation 02 00 0.165 5. Sphincteric involvement 06 07 0.746 6. Hydrocephalus 05 03 0.246 7. Neuro-orthpedic syndrome 15 26 0.292

TABLE 2. Represents Statistical Significance of Operative Results in Group I and Group II

Sl. Surgical outcome Group I Group II Fishers Exact No. n = 19 n = 27 test (5%)

p value

1. Motor Weakness (Improved) 04 06 0.716

2. Sensory loss (Improved) 05 07 1.000

3. Sphincteric dysfunction (Improved) 04 05 1.000

children with lower limb weakness, 3 had paraplegia with complete anesthesia. Autoamputa t ion of little toe was seen in two children and sphincter disturbance was noted in 6. Three children showed non-healing trophic ulcers on the i r feet. N e u r o - o r t h o p e d i c s y n d r o m e (NOS) was observed in the form of sco l ios i s /hemiver tebrae and congenital talipes equino varus in five each, congenital dislocation of hip in two, rib cage anomaly in one and leg length discrepancy in two cases. Two children with MMC also had a patch of hair near the sac. Children having MMC and SCM s i m u l t a n e o u s l y were l abe led as harboring the "complex spina bifida".5

110 Indian Journal of Pediatrics, Volume 72--February, 2005

Comparative Study of Complex Spina Bifida and Split Cord Malformation

Multiple neurofibroma

Cutaneous i:__4 I l scm without J mmc.n=27

0 5 10 15

No. of Patients

Fig 3. Occurrence Of Cutaneous Markers in Group I & II

6

5

~4 JR ~a b O ~2

1

Ilscm with mm.n=19 mscm without mmc.n--27

2, 2 2 2

Hydrocephalus Chlarl Corpus Aqueductal malformation callosum stenosis

dysgenesls

Fig 7. Associated Cranial Lesions In Group I & II

Rib cage deformity

Foot valgus deformity

High arctl foot

Congenital hip distocatio0,

Leg length discrepancy

Congenital tallpes equinovarus

Soollosis/H emivertebr~

m l

m l

m 2

mmmcm wt the~ ~ 7 ml Icm with mine.n=19 I

i i i

0 2 4 6 8 No. of PIHIml

Fig 4. Neuro-orthopedic Syndromes in Group I & II

14

12

10

8

"6 6 d z 4

2

0 Motor wedmelll Itrlle4ry Iole Sphlncterlc Autolcnpullmtlon Trophlr ulc*r

dysfunetian of t o ~

Fig 5. Clinical presentations in Group I & II

20 18 16

_ .14 ! 1 2 " 10 o 8 d z 6

4

1 8

9

201i 0 -

Fig 6. Associated spinal anomalies in Group I & II

1 0

Four of 19 children were operated for MMC at peripheral hospital at birth by general surgeon without adequate investigation, where incomplete surgery was performed. These children had progressive deterioration in neurological function within 6 years of their primary repair, the oldest child being 6�89 with non- healing trophic ulcer over the right great toe and 50% hypoaesthesia on dorsum of foot. Another 4 years old boy, whose meningomyelocele was operated, following the shunt insertion for hydrocephalus at one month of life, presented with rapid onset of paraplegia with sphincteric dysfunction and anesthesia below L-1 dermatome. One patient had progressive bilateral congenital talipes equino varus and another had history of frequent falls and weakness of both lower limbs, after two years of surgery. MR scan of these children revealed underlying split cord malformation.

GROUP II (SCM WITHOUT MMC)

Group II, consisting of 27 children, presented with cutaneous stigmata, progressive neurological deterioration or both, leading to clinical suspicion of tethered cord syndrome. Of cutaneous markers, hypertrichosis was present in thirteen children, cutaneous capillary hemangioma in four and dermal sinus with skin dimple in three. A 14-year-old boy had multiple neurofibromas all over the body with cervical cord splitting and anamolous vertebral bodies. Two patients in this group presented with low backache paraesthesia and progressive weakness of lower limbs. Eleven of the twenty seven children manifested mainly with progressive and asymmetric motor deficit, one child had left leg weakness only. Ten patients had graded or patchy hypoaesthesia below the level of lesion. One child presented with non-healing trophic ulcer on the foot at the pressure points. Seven patients had sphincteric involvement in the form of urinary incontinence and constipation of varying severity.

Amongst the neuro-orthopedic syndrome (NOS), congenital talipes equino varus (one bilateral) was seen in five children and nine had progressive scoliosis. Rib cage anomaly in 1, limb length discrepancy in three, high arch foot in 1 and valgus deformity of foot in 1 were other

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types of NOS seen in this group of patients.

Radiological Findings

Plain X-ray spine of two patients of group I had bony spur visible at the l umba r and dorsa l spine, two had h e m i v e r t e b r a e in dorsal sp ine and 4 pa t ien ts had deficient posterior arch.

Out of total 46 cases of SCM, 38 patients had type I and 8 had type II SCM. Fifteen children of group I had type I SCM, while four had type II SCM. In group II patients SCM type I was present in 23 of 27 and SCM type II in four cases.

Bar d iagrams (Fig 6 and 7) show the incidence of various associated spinal and cranial lesions in both group I and II cases of SCM. Only nine patients of group II, who had split cord in dorsal region, had normal position of the conus. The other eighteen cases had their conus ending between L2 and $2. Of 19 patients of group I, nine had low-lying cord ending below L2, whereas in ten patients conus was lying at the level of L2. Hydrosyr inx was observed in seven patients of group I and in 4 of group II children. H y d r o s y r i n x in both the g roups remained rostral to the defects and extent was 2-4 vertebral level except in one of group I patient, who had hotocord syrinx. None of these patients warranted surgery for the syrinx in isolation. Neural placode was seen in all patients of group I, whereas in t r a sp ina l l ipoma in 4, d e r m o i d in 1, arachnoid cyst in 2 and thick/fatty ilium seen in 5 cases. In g roup II o ther associated te ther ing lesions were intraspinal lipoma in 7, intraspinal dermoid in 3 patients and neurenteric cyst in only 1 patient. Neural placode was not found in any of the children of group II.

Five patients of group I had hydrocephalus, of which two were symptomatic to have enlargement of head and bu lg ing fontanel le . These two r equ i r ed shun t CSF diversion before definitive surgery. Two children became symptomatic on long-term follow-up with progressive enlargement of head, proved on serial scans and required vent r icu loper i toneal shunt ing while one other child remained asymtomatic. Three children of group II had h y d r o c e p h a l u s , two of them had s y m p t o m a t i c hydrocepha lus and required shunt before definit ive surgery. One patient, whose preoperative scan showed minimal ventricular dilatation, required shunt in follow- up, as he developed clinically significant increase in head size.

In g roup I, two children had dysgensis of corpus- ca l losum and a n o t h e r two s h o w e d Arno ld Chiar i malformat ion. Aqueducta l stenosis was noticed in 2 patients. In group II, none of the patients had Arnold Chiari Malformation (ACM), but aqueductal stenosis was noted in two children.

SURGICAL PROCEDURE AND FINDINGS

Surgical Procedure Bony spur in type I SCM was extradural, to lie between

two dural tube. After laminectomy, bony spurs were identif ied following separat ion of two dural sleeves. Complete excision was done with small rongeur or micro drill. Both dural tubes were opened in their midline; usually there are fibrous adhesions with hemicords and dura on medial side. After opening dura, a thorough adhesiolysis was done and dural closure pe r fo rmed posteriorly in such a manner to form a common tube for bo th the cords. In type II SCM, the two cords were exposed and identified till the two become single rostraUy and caudally. Fibrous septum between two was excised, arachnoids adhesions and anomalous nerve roots were also divided to allow free mobility of both the cords. A tight filum terminale, if diagnosed was also divided and a watertight dural closure done. Excision and repair of MMC sac were performed simultaneously in cases having meningomyelocele. At times, fascial graft or synthetic dura was used for lax dural closure. Associated tethering les ions like de rmoid , l ipoma were also r e m o v e d simultaneously.

Surgical Findings

In group I, SCM was found one to two vertebral levels ros t ra t in 14 cases, whi le it was ~t the level of meningomyelocele in five cases. In none of the case, SCM was caudal to MMC. While in group II, SCM was found e i the r benea th the c u t a n e o u s marke r or in close proximi ty , coinciding with bony anomalies of spina bifida.

Var ious Image f ind ings (as descr ibed u n d e r radiological findings) were confirmed during surgical procedure. However, four of group I and one of group II patients macroscopically showed that some of the nerve roots were seen very thin and atrophic as compared to others. In five of group I and three of group II children, few nerve roots were seen significantly adherent to dura with arachnoid bands. Considering these as additional tethering lesions, these were also divided. One case of group I had intramedullary abscess without the prior evidence of infection, dermal sinus or previous surgery.

Surgical Outcome

Table 2 compares surgical outcome and their statistical s ignif icance in g roup I & II. Backache was re l ieved dramatically in both the patients of group II. Trophic ulcers healed well in all three patients of group I and in one child of group It, at about 3 months of follow-up. Of the ninteen (Group I = 9, Group II =10) patients who had variable degree of g raded /pa t chy hypoesthesia below hip, twelve patients (Group I = 5, Group II = 7) showed significant improvement in follow-up at one and half to 6 months with minimal residual hypoaesthesia. Nine of twen ty - th ree pat ients (Group I = 12, Group II = 11) presenting with variable amount of leg weakness, showed gradual recovery in power, (group I = 4, group II = 5) at follow-up of six months to one year. Only two patients of group II had nearly complete recovery in power.

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Pre-operative sphincter dysfunction was present in 13 patients (group I = 6, group II = 7) Five patients belonging to g roup II s h o w e d sa t i s fac tory i m p r o v e m e n t subjectively, whereas only four children of group I had improvement in the bladder function with increase in their dry periods. Neuro-orthopedic syndrome (NOS) became stabilized in all patients of group I and group II, no further improvement or deterioration was noticed in follow-up. However, we feel that the physiotherapy and management of neuroorthopedic deformities were not adequate in most of these children.

POST OPERATIVE COMPLICATIONS

Post-operative CSF leak occurred in eight patients of group I and three of group II. Five of group I and one of group II required re-exploration and repair of dural defect with facia lata patch or synthetic graft (Gore tex), whereas 3 of group I and 2 of group II were treated conservatively with pressure dressing and acetazolamide therapy and they responded well. Pseudomeningocele was noticed in five of group Iand three of group II patients. One patient of group I required thecoperitoneal shunt. Two patients r equ i red r eexp lo ra t i on and repair , whereas in two pat ients only aspirat ion and pressure dressing were needed. In group II, one child required reexploration and repair , whereas in two pat ients only aspira t ion and pressure dressing were done. Four patients in group I and two of g roup II d e v e l o p e d meningi t is . All of them responded to antibiotic except one patient of group I who died due to fulminant meningitis. One child of cervical complex spina bifida expired while recovering in post- opera t ive per iod due to sudden r e sp i r a to ry arrest. Ins tabi l i ty of cervica l sp ine was b l amed for such catastrophe.

DISCUSSION

SCM is not an uncommon finding in spinal dysraphism2 ~ n On review of our total 138 patients of spinal dysraphism SCM constituted 46 of all, reflecting an incidence of SCM to be 33 % (46/138), slightly more than reported by others, which may be on account of referral bias. 3 Nineteen children of MMC had SCM, which represent 14% of total spinal dysraphism cases. Previous pathological studies of children with MMC revealed a significant incidence of associated SCM. Campbell et al s found 36 cases of SCM in 100 infants of open spinal dysraphism and Emery & Lendon 9 reported 78 cases amongst 100 spinal dysraphic patients. In the present study nineteen children of MMC with unsuspected SCM could not have been diagnosed without an awareness of such coexistence. Hence, it is apparent from the above observations that the association of SCM in MMC is not an infrequent finding, which needs a special attention while screening and planning to treat these children for favourable results.

SCM is more common in females according to western

Indian Journal of Pediatrics, Volume 72--February, 2005

literature 2. 3. n but male predominance is seen in Indian subcontinent, including the present study?.6.12

The skin mani fes ta t ions in occul t d y s r a p h i s m represent minor aberrations in the development of the surface ec tode rm, b r o u g h t abou t by the adve r se influences of a dorsal endomesenchymal tract, but these changes are overshad6wed by changes in the surface ectoderm in case of an associated meningomyelocele. 4.5,'3- is The skin markers are quite frequent in occult spinal d y s r a p h i s m i.e. in SCM. In the p re sen t series, the incidence of cutaneous marker is 90% in group II cases as compared to only 10.4% in group I , 3'4' 10.16 signifying a low incidence of cutaneus markers in SCM presenting with meningomyelocele. It is an important observation because these cases of SCM have a h igher chance of missed diagnosis without awareness. Amongst these markers the hypertrichosis was the commonest, being present in 50% of the cases of group II. The other markers like capillary hamangiomas and dermal sinus were seen in group II only and not in group I. This agrees to the consensus of incidence of cutaneous markers in occult dysraphism varying between 20 to 75%. 4,7,17-21

Neuro log ica l defici ts , as such are c o m m o n in m en in g o m y e lo ce l e , these become fu r the r dense in presence of other tethering lesions like SCM in same patients.13. 22 Cons ide r ing the h igh poss ib i l i ty of p rog res s ive and of ten i r revers ib le neuro log ica l deterioration, it is logical to advocate the screening of entire spine with MRI in every spina bifida child. If SCM is found in association with MMC, it should be treated simultaneously to circumvent its deleterious effect on the developing cord. 4 While comparing both the groups, it w a s observed that the incidence of neurological deficit w a s more significant in group I as compared to group II: motor weakness (63.1% vs 40.7%), sensory loss (47.3% v s

37%) and sphincter involvement (31.5% v s 25.9%) (Table 1). Following surgery the improvement in neurological functions were more marked in group II cases compared to group I : motor weakness (54.4% v s 33.3%), sensory functions (70% vs 66.6%) and bladder control (71.4 v s

66.6%) (Table 2). While the incidence of neuro-orthopedic syndrome was 66.6% in group I and 96% in group II patients, this is in accordance with other reported series. ~.4

Children with MMC or previously operated for open defect tend to have more wound complication and CSF leakage, because of the thin skin covering the lesion. 4 Similar observations were made in the present s tudy (42.7%).

A m o n g s t associa ted c ran iosp ina l anomal ies , hydrosyrinx was seen in 7 of 19 (36.8 %) cases of group I and 4 of 27 (14.8 %) of group II, which is within the reported range of 25 to 40%. n.~5~~ but relative incidence is higher in group I cases in this series. Amongst the other anomalies Chiari malformation (ACM) was present in 13% of cases of group I and none in group II suggesting an association, more with MMC and least with SCM. Moreover the incidence of clinically significant ACM in

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cases of s p i n a l d y s r a p h i s m r a n g e s f rom 30 to 50% in exist ing l i terature, 14 bu t no compara t ive da ta is avai lable for t w o g r o u p s of SCM r e p o r t e d b y us. The o v e r a l l i n c i d e n c e of h y d r o c e p h a l u s in m e n i n g o m y e l o c e l e is r e p o r t e d as 86% in wes t e rn l i te ra ture ; 15 in the p r e se n t s t u d y , i t w a s e n c o u n t e r e d in 5 / 1 9 (26.3%) of g r o u p I pat ients and 3 / 2 7 (11.11%) of g roup II pat ients , which is 17.39% of total n u m b e r of cases. O u r p r e v i o u s s tud ies 5.6 and o the r s t ud i e s 12 f rom Ind i an s u b c o n t i n e n t r evea l ed a lmost s imilar low incidence of hyd rocepha lus in cases of SCM. Though the incidence of hydrocepha lus is relat ively more in cases of SCM with MMC, a larger s tudy wou ld be requi red to es tabl ish it.

I n c i d e n c e of l o w l y i n g c o r d in SCM w i t h M M C is r e p o r t e d 30% b y I s k a n d e r whe rea s in p u r e SCM it was found in 40.5% of cases as r epor ted b y Ersahin et al. 1~ In our series, it was not iced in 47.3%, and 66.6% of g roup I a n d g r o u p II p a t i e n t s r e s p e c t i v e l y . W e e n c o u n t e r e d r e l a t i ve ly h i g h e r i nc idence of low l y i n g c o r d s in b o t h g r o u p s of cases. In t r a sp ina l l i poma was the s igni f icant f inding in the present s tudy, both in g roup I, 4 /19 (21.0%), and g roup II 7 /27 (25.9%). Barring two pa t ien ts in g roup I, in w h o m l i p o m a w a s ros t ra l to the sp l i t cord , all the p a t i e n t s h a d d i s t a l l i p o m a s in b o t h t he g r o u p s . This coincides wi th the repor ted incidence of terminal l ipomas by Pang 4 w h o encoun te red 6 l ipomas in total 37 cases of SCM. Othe r a s soc i a t ed les ions wi th SCM are d e r m o i d , e p i d e r m o i d , a r a c h n o i d cys t a n d n e u r e n t e r i c cyst , as repor ted in l i terature. 6. lz 23

Type I SCM was encounte red in 38 of 46 (82%) of our cases, wh i l e type II was seen in rest of 8 chi ldren. As an addi t iona l observa t ion , 15 of 19 (79%) ch i ldren of g roup I (SCM wi th MMC) h a d t ype I SCM s i g n i f y i n g a h ighe r inc idence of b o n y s p u r in cases of SCM assoc ia ted wi th meningomyelocele . It was interest ing to note that 14 of 19 s p l i t c o r d m a l f o r m a t i o n s w e r e l o c a t e d o n e o r t w o v e r t e b r a l l e v e l s r o s t r a l to m y e l o m e n i n g o c e l e s a n d r e m a i n i n g 5 w e r e f o u n d a t t h e l e v e l of men ingomye loce le s itself. It is obvious that no SCM was f o u n d b e l o w t h e l e v e l of M M C . T h e t y p e I SCM is repor ted to have h igher incidence of 75% in compar i son 25 of type I I in l i terature. '~ 12 A h igher incidence of type I SCM is r epor t ed in cases associated wi th MMC by Pang et aP ~ and Ersahin et a12 ~

O c c a s i o n a l l y , the s h o r t e n e d n e r v e roo ts , con jo ined nerve roots, angu la t ed nerve roots and a rachno id bands are seen at the level of dys raph ic state, caus ing te ther ing of cord. 24, ~ L a s s m a n and James have d e v i s e d the te rm 'meningoce le m a n q u e ' for the cases in w h o m adhes ion of the conus, filurn, cauda equina roots to the inner aspect of t he p o s t e r i o r d u r a o c c u r . 26 The p r e s e n t s e r i e s a l s o wi tnessed the thin and aberrant nerve roots in 4 of goup I and1 of g r o u p II pa t i en t s , w h e r e a s n e r v e roo t s we re adherent to dura wi th arachnoid bands in 5 of g roup I and 3 of g roup II cases. The presence of such s t ructures , most p robab ly s ignify the add i t iona l te ther ing elements , need to be ca tered d u r i n g surgery.

CONCLUSION

The incidence of SCM wi th meningomyeloce le be ing 41% of t o t a l SCM c a s e s is o b v i o u s l y s i g n i f i c a n c e . T h e p rognos i s of SCM wi th M M C is no t as good as no ted in pu re SCM cases. Progressive sensor imotor deficit also has h igher incidence in cases of SCM wi th MMC, whereas the incidence of NOS is re la t ively more in pure SCM cases. A screening of entire neural axis is seemingly indispensable , in o rde r to cater to the occult associat ions s imul t aneous ly (in cases of overt spina bifida) for bet ter outcome. Because of s ignif icant occurrence of M M C in SCM and concurrent hyd rocepha lus , it seems a p p r o p r i a t e to inves t iga te these c h i l d r e n t h o r o u g h l y b y c r a n i o - s p i n a l MRI. In case of equivocal radiological f indings, SCM should be searched one to two level h igher than MMC, if not p resen t at s ame level in v iew of i t s 'h igher inc idence of rostral location.

A c k n o w l e d g e m e n t

The authors are extremely grateful to Mr. A.P. Dhar Dwivedi for preparation of this manuscript.

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Book Available

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Indian Journal of Pediatrics, Volume 72--February, 2005 115