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Orthopaedics & Traumatology: Surgery & Research (2009) 95, 547—550

CLINICAL REPORT

Split cervical spinal cord malformation andvertebral dysgenesis

C. Androa,∗, R. Pecquerya, P. De Vriesa, P. Forlodoub, B. Fenoll a

a Pediatric Orthopaedic Surgical Unit, Morvan Hospital, 5, avenue Foch, 29609 Brest Cedex, Franceb Radiology Department, Morvan Hospital, 5, avenue Foch, 29609 Brest Cedex, France

Accepted: 17 July 2009

KEYWORDSDiplomyelia;Spinal dysgenesis;

Summary We report a case of vertebral malformation associated with diplomyelia believedto be a type II split cord malformation. Cervicothoracic level cases are exceptional. Thisarticle reports the case of an 11-year-old boy with no neurological symptoms who had not

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Neural tube defects;Cervical vertebrae;Congenitalabnormalities

undergone surgery. The diagnosis was made during pregnancy by prenatal screening with ultra-sound and MRI. Several embryological theories have been offered to provide an explanation forthis syndrome. Close follow-up is mandatory. Surgery must only be considered if neurologicaldeterioration occurs.© 2009 Published by Elsevier Masson SAS.

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Introduction

We report an exceptional case of split cord malformation(SCM), associating diplomyelia and cervicothoracic verte-bral malformation. These abnormalities are more frequentlyobserved in the thoracolumbar region [1]. To date, onlyabout 30 cases with cervical segment involvement havebeen described and each presented morphological speci-ficity [2—5]. After the presentation of our patient, theembryological hypotheses and the anatomical and clinical

characteristics of this remarkable case will be discussed.Finally, we will discuss the main therapies and the course tofollow.

∗ Corresponding author.E-mail address: christopheandro@hotmail.com (C. Andro).

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n 11-year-old boy was born at term by vaginal birth. Heas the second child of two children. There was no familyistory and no evidence of consanguinity. At 28 weeks amen-rrhea of pregnancy, the ultrasound examination revealedmalformation associating intrauterine growth delay syn-

rome, type A omphalocele, and a cervicothoracic spinealformation.These abnormalities called for prenatal amniocentesis

aryotyping, which was normal (46XY).The prenatal MRI showed small lateral evaginations of the

pine, but did not provide a precise etiological diagnosis for

his malformation.

At birth, the neurological exam was normal and no otherssociated locomotor system or visceral malformation wasound. The integument, particularly the median cleft, wasormal. The first radiographs taken at birth showed a spinal

served.

548 C. Andro et al.

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igure 1 Thoracic spinal column CT (horizontal slice): bonyefect of the anterior and posterior arch showing hemicordspect.

alformation extending from C3 to T7, with a split spinespect.

The CT exam demonstrated that the cervico-occipitalinge was normal. In the spine, only the first and secondervical vertebrae were normal. The other cervical and

horacic vertebrae, down to T7, were split in two. Theertebral bodies and the posterior arcs were not closedt the maximum gap of the two hemicords, resulting inn anterior and posterior bone defect (Figs. 1 and 2).

igure 2 Cervicothoracic spinal column CT (3D reconstruc-ion): division of the cervicothoracic spinal column and ribalformations with deformation of the rib cage causing restric-

ive pulmonary syndrome.

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igure 3 Spinal cord MRI (AP view): diplomyelia limited to theegion where the gap between the two hemicords is maximum.

his abnormality was associated with rib malformations,esponsible for a deformity in the thoracic cage.

The medullary canal MRI showed a dural sheath that fol-owed the spinal deformity. At the cervicothoracic junction,here was a division of the medulla forming diplomyeliaulling laterally to the right and left, with the nerve roots ofhe upper limbs emerging from this area. An osseocartilagi-ous septum could not be demonstrated between the twoemicords (Fig. 3). There was no encephalic abnormality.

The child was 11 years old at the time this article wasritten. He presented a balanced growth delay of −2 stan-ard deviations, his psychomotor development was normal,s was the neurological exam. He was 129 cm tall. Hettended middle school and took part in recreational sports.rom a morphological point of view, he presented a shorteck, reduced cervical range of motion, and low posteriorair implantation (Fig. 4). He underwent respiratory physi-al therapy for restrictive pulmonary syndrome, which wasesponsible for frequent bronchopulmonary superinfections.ntil now, the child has received simple medical and surgicalonitoring. No surgical treatment has been undertaken.

iscussion

his type of malformation is exceptional. To date, few casesf cervicothoracic vertebral-spinal column malformationsave been described in the literature.

Clinically speaking, this case suggests Klippel-Feil syn-rome. This syndrome associates the classical clinical triadf low posterior hair implantation, a short neck, and lim-ted range of motion in the neck found in this child. Fromn anatomical point of view, this syndrome is character-

zed by congenital fusion of the cervical vertebrae. In theresent case, there was no vertebral fusion, but rather aplit spine aspect, eliminating Klippel-Feil syndrome. How-ver, David et al. [2] reported seven cases of Klippel-Feil

Split cervical spinal cord malformation and vertebral dysgenesis 549

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Figure 4 The patient presents as with Klippel-Feil sy

syndrome associated with a double cord, or SCM, with aclinical presentation very close to our patient’s.

Definition of split cord malformation (according toPang et al. [6])

Notochordal-dysraphic disorders are rare congenitalvertebral-spinal malformations, including SCM. The variedradiological and clinical forms of this syndrome partiallyexplain the controversy on its exact definition. Severalauthors have established definitions. According to Pang etal. [6], there are two types of SCM. Type I, or diastemato-myelia, consists of two hemicords in two individual duraltubes, separated by a rigid osseous or cartilaginous septum.

Type II, or diplomyelia, corresponds to two hemicordshoused within a single dural sac, separated by a fibrousseptum. The case reported herein is similar to type IISCM. These spinal malformations are often associatedwith vertebral abnormalities: hemivertebrae, butterfly

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Figure 5 A, B, C: normal and pathological embryology (accordingplate/tube; 3: somite/sclerotome; 4: notochord; 5: endoderm; 6: neof the accessory endoderm/neurenteric canal.

me: a short neck and low posterior hair implantation.

ertebrae, vertebral fusions, or spina bifida. However,complete division of the spinal cord as in our case is

xceptional.This syndrome’s clinical and radiological presentation is

ighly variable, with, however, a predominant involvementf the thoracolumbar segment and a higher frequency inirls. Diagnosis is most often made during childhood, at aean four years after the appearance of the first symptoms.owever, the diagnosis can also be late because when there

s no clinical manifestation [5]. Currently, prenatal imag-ng techniques (ultrasound and MRI) can detect this type ofbnormality during pregnancy.

ormal and pathological embryology

he etiopathogenesis of SCM syndrome has not been clearlystablished to date (Fig. 5). Several embryological hypothe-es have been developed: abnormalities in the neural tube,oubling of the cord, persistence of an abnormal neurenteric

to Larsen [7], David [2], and Pang [6]). 1: ectoderm; 2: neuralural hemi-tube/diplomyelia; 7 hemi-notochord; 8 invagination

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anal, a hydrodynamic process, and the twin monster theoryimited to one segment [2,3,5—7].

The development of the spinal column and cord beginsn the third week of embryonic development with the dif-erentiation of the germ layers (ectoblast, mesoblast, andndoblast) [8]. The key structure in this development ishe notochord, which emerges from the endoderm. Theotochord constitutes the axis around which all the othertructures later develop. During primary neurulation, theotochord induces the formation of the neural plate at thectoblast level. This will then invaginate to form the neu-al tube, the source of the spinal cord. The formation ofhe vertebral column occurs toward the 17th day of embry-nic life: mesmerization of the para-axial mesoblast formsairs of somites from the action of the signals emitted forhe most part by the notochord and the neural tube. Theells of the medial and ventral walls are deposited aroundhe cord to form sclerotomes, which fuse to give birth touture vertebral bodies. The cells of the somites’ dorsalalls migrate around the neural tube and form the posteriorrches (Fig. 5A, B).

Cervical SCM occurs during primary neurulation (Fig. 5C).ccording to Pang et al. [6], a lesion on the medial line fromdherence between the endoderm and the ectoderm cre-tes an accessory neurenteric canal. This canal induces theivision of both the notochord and the neural plate at oneegment of the embryo. The two resulting hemi-notochordsehave like two autonomous cords, which each induce aeural tube and somites. At the end of development, thepinal cord that is separated into two, frequently associatedith vertebral abnormalities in one segment of the vertebralolumn.

In type I SCM (diastematomyelia), the existence of twondividual dural tubes, separated by a rigid septum, could bexplained by the incorporation between the two hemitubesf primitive cells to the sclerogenic potential. They form aedian dural wall and a osseocartilaginous septum between

he two hemicords [6].At the cervical level, a fibrous septum is described most

requently (type II SCM or diplomyelia), as in the caseeported herein.

In addition, the vertebral column of the child in thiseport presented an aspect of separation into two hemi-ords, which is explained by the simultaneous presencef an anterior and posterior bony defect. In 1996, Davidt al. [2] reported seven cases of cervical SCM associatedith vertebral abnormalities. They classified them into tworoups: those having a defect in the posterior arch andhose presenting an anterior osseous defect. This report pro-ides an embryological theory for each case. The posteriorefect may be related to a neural tube-closing abnormality,hereas the anterior defect may be secondary to invagina-

ion of the endoderm, preventing fusion of the sclerotomes.ur case is even more remarkable in that the two defectsccur simultaneously.

linical considerations

he indications for surgical treatment in cervical SCM remainighly controversial. The appearance of medullary pain con-itions the course to follow.

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C. Andro et al.

The cases of cervical SCM reported in the literature areostly asymptomatic. One explanation would be that in the

ervical region there is less often a rigid septum, and likehe difference in growth speed between the spinal cord andhe vertebral cord, it would be less substantial in this region4,9], spinal shearing and adherence phenomena (tetheredpinal cord) may be less frequent.

Finally, microinjuries related to flexion and extensionovements of the vertebral column may be limited because

f cervical stiffness.Most authors do not recommend prophylactic surgical

reatment. Close clinical monitoring is recommended forhese patients. The appearance of neurological signs shouldpen the discussion of surgical management, particularly ifhey are evolving.

onclusion

CM syndrome is rare and its varied anatomical and clinicalorms make it difficult to study and develop standardizedanagement.The development of prenatal imaging with ultrasound

nd MRI allowed us to make a very early diagnosis for thisase and follow up the patient since birth.

Management should be multidisciplinary and individual-zed since each case is unique.

When present, the neurological deficit is often at theorefront, but it should not overshadow the pulmonaryepercussions and the deformation of the rib cage.

Recourse to surgery should be envisaged only if there islinical deterioration.

onflicts of interest

one.

eferences

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2] David KM, Copp AJ, Stevens JM, Hayward RD, Crockard A. Splitcervical spinal cord with Klippel-Feil syndrome: seven cases.Brain 1996;119:1859—72.

3] Lassale B, Rigault P, Pouliquen JC, Padovani JP, Guyonvarch G.La diastématomyélie ou syndrome de la double chorde : étudede 21 cas. Rev Chir Orthop 1980;66:123—40.

4] Pang D. Split cord malformation: Part II: clinical syndrome. Neu-rosurgery 1992;31:481—500.

5] Verneret C. Diastématomyélie. In: Chirurgie et orthopédie durachis : enfant et adolescent. Montpellier: Sauramps Medical ed;1989, 373—8.

6] Pang D, Dias MS, Ahab-Barmada M. Split cord malformation: PartI: a unified theory of embryologenesis for double spinal cordmalformations. Neurosurgery 1992;31:451—80.

7] Klessinger S, Christ B. Diastematomyelia and spina bifida canbe caused by the intraspinal grafting somites in early avianembryos. Neurosurgery 1996;39:1215—23.

8] Larsen WJ. Embryologie humaine. Bruxelles: Deboek Université;1996.

9] Eller TW, Bernstein LP, Rosenberg RS, Mc Lone DG. Teth-ered cervical spinal cord. Case report. J Neurosurg 1987;67:600—2.