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60 Spina Bifida and craniocervical junction anomaly. A case report Zahia VERNEX-BOUKERMA, Pierre CORRE, Jean-Philippe PERRIN, Roman Hossein KHONSARI, Jacques MERCIER, Jean-Michel SALAGNAC Address for correspondence: Z. VERNEX-BOUKERMA Clinique de chirurgie maxillo- faciale et stomatologique, CHU, 1, place Alexis Ricordeau 44093 Nantes Cedex 1. ABSTRACT Introduction Spina bifida is a rare congenital disorder due to a closure anomaly of the neural tube. Clinical case A 9 years-old girl presents with lumbar spina bifida aperta and cervical spina bifida occulta. Her case illustrates the importance of orthodontic xrays in the diagnosis of cervical spine malformations. Discussion There are two categories of spina bifida. When refered to as aperta, the disorder associates a dorsal vertebral bony gap and an involvement of the spinal cord. A skin pouch can form and include meninges alone (meningocele) or meninges with spinal cord (myelomeningocele). Spina bifida is generally located in the lumbar or sacral regions, and extends over 2-3 vertebrae. On the other hand, the involvement of the cervical spine is often of the occulta type, where the defect is covered by skin and is limited to the bone. This rare condition cannot be ignored by the clinician as the craniocervical junction anomalies induced by this malformation can be associated with C1-C2 instability, as in our case report. KEYWORDS Spina bifida aperta Spina bifida occulta Arnold-Chiari malformation Craniocervical junction anomaly Meningocele Myelomeningocele C1-C2 instability. DOI: 10.1051/odfen/20084210077 J Dentofacial Anom Orthod 2008;11:60-67 © RODF / EDP Sciences Article available at http://www.jdao-journal.org or http://dx.doi.org/10.1051/odfen/20084210077

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Spina Bifida and craniocervicaljunction anomaly. A case report

Zahia VERNEX-BOUKERMA, Pierre CORRE, Jean-Philippe PERRIN, Roman Hossein KHONSARI, Jacques MERCIER, Jean-Michel SALAGNAC

Address for correspondence:

Z. VERNEX-BOUKERMA

Clinique de chirurgie maxillo-faciale et stomatologique, CHU, 1, placeAlexis Ricordeau 44093Nantes Cedex 1.

ABSTRACT

IntroductionSpina bifida is a rare congenital disorder due to a closure anomaly of the neural tube.

Clinical caseA 9 years-old girl presents with lumbar spina bifida aperta and cervical spina bifida

occulta. Her case illustrates the importance of orthodontic xrays in the diagnosis of cervical spine malformations.

DiscussionThere are two categories of spina bifida.

When refered to as aperta, the disorder associates a dorsal vertebral bony gap and an involvement of the spinal cord. A skin pouch can form and include meninges alone (meningocele) or meninges with spinal cord (myelomeningocele). Spina bifida isgenerally located in the lumbar or sacral regions, and extends over 2-3 vertebrae.

On the other hand, the involvement of the cervical spine is often of the occulta type,where the defect is covered by skin and is limited to the bone.

This rare condition cannot be ignored by the clinician as the craniocervical junctionanomalies induced by this malformation can be associated with C1-C2 instability, as in ourcase report.

KEYWORDS

Spina bifida apertaSpina bifida occultaArnold-Chiari malformationCraniocervical junction anomaly MeningoceleMyelomeningocele C1-C2 instability.

DOI: 10.1051/odfen/20084210077 J Dentofacial Anom Orthod 2008;11:60-67© RODF / EDP Sciences

Article available at http://www.jdao-journal.org or http://dx.doi.org/10.1051/odfen/20084210077

Vernex-Boukerma Z. et al. Spina bifida and craniocervical junction anomaly. A case report61

ZAHIA VERNEX-BOUKERMA ET AL.

Spina bifida is a disorder in the clo-sure of the neural tube. The apertaform associates a dorsal vertebralbony gap with an involvement of the spinal cord. A skin pouch can form and include meninges alone(meningocoele) or meninges withspinal cord (myelomeningococele).Spina bifida predominates in the lum-bar or sacral regions, and extendsover 2-3 vertebrae. The clinical severi-ty of the lesion depends on theinvolvement of the spinal cord.

Spina bifida in the cervical spine isgenerally of the occulta form. The gapis then limited to the bone. The diag-nosis of the malformation is oftenmade by chance, when the C1-C2instability resulting from the cranio-cervical junction anomaly induces theapparition of neurological signs.

Our case report is the occasion toinsist on the fact that this malforma-tion can be also diagnosed with stan-dard orthodontic X-rays.

1 - INTRODUCTION

2 - CASE REPORT

A 9-years old girl (fig. 1 a, b, c) wasreferred to our department for theextrac tion of teeth 14, 24, 34 and 44in the course of her orthognatic treat-ment. She suffered from a major den-tal crowding interfering with normalcanine growth (fig. 1 c, fig. 2).

Facial and lateral cephalometric X-rays (fig. 3) and a orthopantomo-

gram (fig. 2) were realized and stud-ied by the orthodontist; the patientwas sent to the maxillofacial surgeonto realize the extraction. Surgicaldecision of the extraction was doneafter examination of the case.

This young patient is also followedup by a child orthopedist. At 24 hoursof age, she was operated for a lumbar

Figures 1 a to cYoung patient, 9 years-old.

a: full facial view; b: profile view: good facial balance; c: front view of occlusion: dentalcrowding.

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SPINA BIFIDA AND CRANIOCERVICAL JUNCTION ANOMALY. A CASE REPORT

spina bifida aperta and still carried aventriculo-atrial shunt for hydrocephaly.The patient depends on a wheelchairfor her movements and cannot stayseated with the neck extended for along period. In her first years of life, shealso benefited from talipes surgery,numerous varisation osteotomies ofher knees and dorsal relaxation for sco-liosis. She furthermore suffers from anallergy to latex.

The extractions proposed by theorthodontist where part of a treatmentplan designed to be as light as possible,to avoid any excessive medical care.

The observation of the orthodonticcephalometric X-rays and of theorthopantomogram performed by theorthodontist led us to fear a craniocer-vical junction anomaly. In fact, the pro-cessus spinosus of C2 was doubled;furthermore, the hypoplastic odon-toid (fig. 3, fig. 5 a), was fused withthe occipital bone and a C1-C2spondylolysthesis suggesting a C1-C2instability or C1-occipital instability.Thus, and before any chirurgical actwe have requested a neurosurgeonsstaff to screen any neurologic lesion.

They proceed to dynamic cervicalspine xrays in flexion and extension(fig. 4) to screen C1-C2 instability.They found a rise of C1-C2 spondy-

lolysthesis but the junction was nev-ertheless stable.

CT-scan in osseous window withreconstructions in all plans was per-formed (fig. 5 a to c) to appreciate theimpact on bone structure. It confir-med doubled processus spinosus,hypoplastic odontoid fused with theoccipital bone, and showed an osodontoidum (sesamoid bone of axis)and posterior and anterior arch age-nesy of atlas which having for conse-quence a space of the lateral mass.

MRI, which is the best examina-tion to study medullar anomalies (fig.6 a and b), diagnosed a cervical spinabifida occulta and a hydrocephaly dueto an Arnold-Chiari mal formation typeII. The patient didn’t exhibit any neuro-logical focal signs of syringomyeliaand the hydrocephaly was well con-trolled by the shunt.

No cervical surgery was perfor-med regarding the stability of thejunction. The extractions could thus

Figure 3Lateral cephalograph showing ventrio-atrial shunt and C1-C2 spondylolysthesis.

Figure 2Orthopantomogramm showing 4 cuspidsblocked by the first bicuspids.

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ZAHIA VERNEX-BOUKERMA ET AL.

be performed without compressiverisks on the cervical spinal cord duringthe forced neck extension.

On orthopantomogramm (fig. 2),teeth 13 and 23 were blocked by 14and 24. Teeth 55 and 65 were present,

Figures 5 a to c CT-scan imaging.

a: frontal CT reconstruction: os odontoïdum and double processus spinosum in C2;b: facial view of the 3D reconstruction: agenesis of C2 anterior and posterior arches;c: lateral view of the 3D reconstruction: processus spinosum pf C1 and C2 are apart with spondylolysis in neutralposition.

Figures 4 a and ba: dynamic cervical lat eral X-rays in forced flexion: rise of C1-C2 spondylolysthesis;b: dynamic cervical spine X-rays in forced extension.

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as well as the germs of 15 and 25.Germs of teeth 34, 35, 44, 45 werepresent over temporary dentition and33 and 34 couldn’t grow properlybecause of the major dental crowd-ing. Because of the absence of

mandibular premolar growth, wedecided to extract teeth 14, 24, 84and 74 under local anaesthesia.

The patient is currently followingher orthodontic treatment.

3 - DISCUSSION

Spina bifida is a latin term whichrefers to a posterior opening in thever- tebrae associated to a spinal cordinvolvement. Spina bifida results froma neural tube closure anomaly (incom -plete closure of posterieur vertebralarch) associated with lesion of spinalcord4,12,13,15. It is due to embryologicalanomaly occurred in the 4th week. Itis generally located in the lumbar or

sacral regions and extends over 2-4vertebrae. In France, 0.5/1000 chil-dren present this malformation10,more fre quent in AngloSaxon coun-tries with 8/1000 and 2/1000 inU.S.A13. More precisely, spina bifidawould be the result of a disorder inthe metabolism of folates. Severalgenes are thought to be responsibleof the malformation, such as the

Figures 6 a and bMagnetic resonance imaging.

a: coronal view: major residual hydrocephaly despite the shunt;b: lateral view: widening of the magnum foramen with protrusion of the medullar bulb intothe spinal canal: Arnold Chiari type II malformation.

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ZAHIA VERNEX-BOUKERMA ET AL.

Two main anatomical presenta-tions of Spina Bifida Aperta aredescribed with several severity:

– Meningocoele is the less fre-quent but also the less severe form.The skin pouch adjacent to the spinalbony defect only contains meninges.The spinal cord stays in its normallocation and the spinal nerves are notdamaged.

– Myelomeningococele (fig. 8) ismore severe and unfortunatelyincludes 75% of spina bifida cases.The spinal cord and the spinal rootsare exposed through the spinal bonygap, generally without any skin coverbecause of agenesy of the posteriorarches. When the protruding spinalcord is covered by a thin layer of lep-tomeninges, the anomaly is referredto as spina bifida cystica.

Spina Bifida Aperta is often associ-ated, as in our case, with an Arnold-Chiari type II anomaly, characterizedby a misposition of the bulbar regionof the brainstem and of the cerebel-lum. In fact, these structures can be

MTHR (methylen tetrahydrofolatereductase) gene located in 1p36.313,17

or PAX3 structure gene14. Zincmetabolism has also been incriminated.The syndromic cases, especiallythose resulting from chromosomalanomalies (trisomia 18 for instance,triploidy)10 are generally lethal. Folicacid treatment during pregnancyseems to lower the rate of neuraltube closure anomalies6,13-15.

This malformation can be exterior-ized: aperta form (fig. 7); or closed:occulta form (fig. 7) where thespinosus processus is doubled butcovered with skin.

Figure 7Figures showing different types of spina bifida4.

Figure 8Dorsal view of a new-born child withlombo-sacral myelomeningococele.

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situated as low as C3 when theyshould be enclosed in the skull2,6,9,12-14. Arnold-Chiari type II anomaly is amajor cause of hydrocephaly due tobad circulation of cerebrospinal fluidor defect of absorption.

The prenatal ultrasound diagnosisof spina bifida can be done as soon asthe 11th week of life. The typical echo -graphic signs of spina bifida are:hydrocephaly, feet anomalies (such astalipes) and lack of normal mobility inthe lower limbs. Such signs lead toperform an amniocentesis and lookfor biological stigmata of spinal canalopening such as the rising of alpha-foetoprotein rate in the cerebrospinalfluid.

The treatment of spina bifida is anemergency and has to be performedin the 24-48 hours following delivery.The technique involves the explo-ration of the skin pouch and the closeof the meningeal opening. The patientcan be shunted simultaneously, ormore frequently secondarily if thehydrocephaly is not severe. Foetalsurgery may be the future treatmentstandard13.

Clinical signs reflect the severity ofthe spinal cord involvement: paraple-gia, urinary and/or anal incontinence,dorsolumbar scoliosis, genito-sexualdisor ders, talipes, an allergy to latexprobably due to the great number ofsurgeries2,13,14.

In the particular case of spina bifidaocculta, the anomaly is often discov-ered by chance. Hair on the back mid-line is a classical sign of spinabifida4,15. Less frequently, the patientscan report back pain or develop focalneurological signs1,7,16. The most fre-quent localizations of the occulta formare C1 and C69.

Our patient had a lumbarmyelomeningocoele, a C1 spina bifidaocculta with anterior and posteriorarch agenesis, a doubled C2 proces-sus spinosus, a dens hypoplasy andan odon toïdum bone (sesamoidbone).

Such malformations can mimic thesymptoms of a narrow cervical canal(see the case of a children 8 old ofConnor et al.5, present as a C1-C2instability or lack any clinical manifes-tation). Cervical myelopathy due toSpina Bifida Occulta is very rare1. Itresults from a compression of spinalcord by invagination of doubledspinosis processus and C1-C2 insta-bil ity7.

In the cases without clinical mani-festations, minor trauma or excessivecervical extension can induce theapparition of acute focal neurologicalsigns.

Standard cervical spine X-rays area good source of information for thiskind of anomalies3. Interestingly, iso-lated cervical spondydolisthesis is notfrequent in children and generally pre-dominates on C68. Surgery such asarthrodesis is gener ally not requiredfor this localization but only in case ofpain or focal neurological signs.

Down’s syndrome (trisomy 21) canbe associated with C1 spina bifidaocculta without systematic C1-C2instability7.

In all cases where a spinal cordcompression is suspected, CT-scan(for the visualization of the bonelesions) and actually whith the tech-nology of multislice X-ray computedtomography (provided excellent 3Dreconstruction), and MRI (for the cordand diagnosis of narrow cervicalcanal) are mandatory3,11.

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Spina bifida is not familiar toorthodontists and maxillofacial sur-geons. Nevertheless, as the uppercervical spine is visible on standardorthodontic X-rays, we should sys-tematically look for such malforma-

tions, even when no neurologicalsigns are reported. Early screening isessential because a lot of cephalo-metric X-rays are processed by theorthodontist on very young patients.

4 - CONCLUSION

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