Characteristics and surgery of cervical myelomeningocele
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ORIGINAL PAPERCharacteristics and surgery of cervical myelomeningoceleSheng-Li Huang &Wei Shi &Li-Gen ZhangReceived:2June 2009/Revised:21July 2009/Published online:20August 2009#Springer-Verlag 2009AbstractObjective Cervical myelomeningocele (CMMC)is a rare entity in neurosurgical practice,which presents different clinical characteristics compared with other more common lumbosacral variant.Since not much about this lesion has been reported in the literature,this study,herein,demon-strates by cases the clinical characteristics,methods,and techniques of surgical treatment of CMMC in children.Methods A total of 10children (six boys and four girls)with CMMC were recruited in this study.Their ages ranged from 9days to 8years with a median age of 3months.All patients underwent neurological and radiological examina-tions.One was found to have had a mild unilateral arm weakness,and others were neurologically intact.Of these 10patients,five had other associated neurological or orthopedic anomalies,including mild ventriculomegaly in two,cervical diastematomyelia in one,Chiari II malforma-tion and hydrocephalus in one,and sacral spina bifida occulta in one.Surgical excision of the lesion with intradural exploration of the sac to release any potential adhesion bands was performed for all.Results No complications,such as cerebrospinal fluid leakage and infection,had been found after operation.During the follow-up of 1–7years (mean of 3.9years),all cases did not suffer from aggravation of nervous symptoms.None of the patients deteriorated postoperatively,and the one with left arm weakness improved following surgery.In the two children with mild ventriculomegaly,cerebral ventricle returned to be normal after surgery.Conclusions The management strategies of CMMC are early surgical treatment with standard microneurosurgical techniques to prevent the development of neurological defects.It is safe and effective to adopt surgery excision of the lesions with intradural exploration of the sac to release any potential adhesion bands.Keywords Cervical myelomeningocele .Childhood .Spinal dysraphism .SurgeryIntroductionSpina bifida cystica preferentially affects the lower regions of the spine and is rarely seen in the cervical spine.The posterior midline cutaneous mass lesions of cervical spine have been defined as cervical myelomeningocele (CMMC).CMMC is a rare form of pediatric congenital spinal anomaly forming only up to 3–8%of all cases of spina bifida cystica [1–6].CMMC differs clinically from the more common lumbosacral myelomeningocele.Its specific clinical char-acteristics should be identified;otherwise,patients would be misdiagnosed and subsequently treated incorrectly.As a matter of fact,an inadequate surgical technique can lead to late neurological deterioration [5,7,8].Not much about this lesion has been published in the literature.Most of the original articles are case reports with small numbers of cases [9–12].The authors,herein,report another 10cases of surgically treated CMMC and also discuss its clinical characteristics and management strategies.S.-L.Huang :W.Shi (*)Department of Neurosurgery,The Second Affiliated Hospital,School of Medicine,Xi ’an Jiaotong University,No.157Xiwulu,Xi ’an,Chinae-mail:sweins@L.-G.ZhangDepartment of Surgery,Xi ’an Children ’s Hospital,Xi ’an,ChinaChilds Nerv Syst (2010)26:87–91DOI 10.1007/s00381-009-0975-7Clinical materials and methodsPatientsFrom January2001to June2007,a total of176patients were diagnosed as congenital spine bifida in our hospital,and10of them were recognized to be CMMC.The clinical data of the 10patients were obtained,including age,gender,clinical presentation,associated malformation,pre-and postoperative images,pathological specimens,and surgical procedures,and were analyzed retrospectively.There were six boys and four girls ranging from9days to8years with a median age of 3months.All the patients underwent neurological and radiological examinations,including magnetic resonance imaging(MRI;Figs.1and2).A soft mass at the midline of the back in the cervical region was noted;the mass had a relatively wide dome,covered at the base by a full-thickness layer of skin and at the top by thin purplish skin.No cerebrospinal fluid(CSF)leakage was noted.The diameter of the lesions ranged from2to9cm.One patient had a mild unilateral arm weakness,and others were neurological intact. Of these10patients,five had other associated neurological or orthopedic anomalies,including mild ventriculomegaly in two,cervical diastematomyelia in one,Chiari II malforma-tion and hydrocephalus in one,and sacral spina bifida occulta in one.All patients underwent surgical treatment with standard microneurosurgical techniques and excision of the sac.The outcome and follow-up were evaluated.A summary of the findings is shown in Table1.Surgical proceduresUnder general endotracheal anesthesia,the patient was placed into a prone position with all pressure points padded.At surgery,a longitudinal oval skin incision was made around the base of the mass,and it was dissected circumferentially toward the fascia where the mass narrowed into a stalk,which was seen to merge with the dura.The adjacent laminae were resected.The meningocele sac was sharply dissected.A thick fibrous band was seen to extend through the small opening of the neck up to the dorsal surface of the meningocele sac. The dura was opened around the stalk,which was then seen to enter the enlarged cord in the posterior midline. Using a microsurgical dissection technique,this attach-ment to the meningocele was sharply dissected free,the stalk was amputated at the level of the cord,and a thorough release of the fibroneural bands was thus performed.After this,it was felt that the cord was completely free.Then extirpation of the whole mass was thus performed.And the dura was closed.ResultsSurgeryIn one patient,the sac was removed without any further exploration because there was no fibroneural band in it.In all other patients,a two-level laminectomy or laminotomy was performed,and when identified,the stalks were excised flush to the spinal cord,whenever possible.Postoperative courseAll the patients had an uneventful postoperative course without any noticeable change in their neurological status. No postoperative complications,including cerebrospinal fluid leakage and infection,were encountered.Follow-upAll the patients have a regular follow-up ranging from1to 7years.No patients deteriorated with motor impairment. Postoperative MRI studies were performed in all patients, and the results showed that the spinal cord wasuntethered Fig.1T1-weighted sagittal MRI shows a CMMC at the cervical spineto the dura mater.The patient with left arm weakness improved following surgery,and in the two with mild ventriculomegaly,cerebral ventricle returned to be normal after surgery.All the patients now enjoy good health.HistopathologyThe pathological specimens obtained from 10patients were reviewed.The main histopathological findings were as follows:seven out of 10cases were neuroglial stalks;two out of 10were fibrovascular stalks.DiscussionCongenital spinal anomaly is most common in the lower regions of the spine —the lumbar and sacral regions;the most common form of which is myelomeningocele.CMMC comprises only a small proportion of all myelome-ningoceles.The 10CMMC cases we observed were out of a total of 176cases of congenital spinal anomalies admitted in our hospital during January 2001to June 2007;the incidence of CMMC cases is 5.7%(10/176),similar to that reported in many others studies [1–6].The posterior midline cutaneous mass lesions of the neck area have been described by different terminologies:cervical meningoceles [11,13],cervical myelomeningo-celes [2,5,8,9],and etc.In the most cases,stalks emanated from the dorsal surface of the spinal cord,penetrating into the sac through a defect of the posterior midline structures and adhering to the cystic wall,consist of neuroglial structures;in some cases,the stalk is composed exclusively of fibrovascular elements that also tether the spinal cord to the dura mater and other soft tissues [10].As we all know,the classic definition of meningocele is that of a cystic swelling of the meninges protruding through aspinalFig.2A CMMC with a Chiari II.T1-weighted sagittal MRI showing an associated Chiari malformationTable 1Clinical summary of the patient's information Case no.Age/sexPreoperative deficits LevelAssociated anomalySurgical procedureFollow-up13months/M None C6–7NoneResection,untethering Uneventful 243days/F None C7–T1Mild ventriculomegaly Resection,untethering Uneventful 336days/M None C4–5None Resection,untethering Uneventful 47months/F None C6–7None Resection Uneventful 59days/MNone C3–4NoneResection,untethering Uneventful 61year 6months/F None C5–6Diastematomyelia Resection,untethering Uneventful 72year 7months/M None C6–7NoneResection,untethering Uneventful 83months/M NoneC5–6Mild ventriculomegaly Resection,untethering Uneventful 95years/F Arm weakness C5–6Sacral bifida occultaResection,untethering Uneventful 108years/M NoneC6–7Chiari II malformation,hydrocephalus Resection,untethering UneventfulF female,M male,C cervical,T thoracicdefect,with the spinal cord remaining entirely confined to the vertebral canal[14].True meningocele,in the strictest sense,is rarely found in neck area.Considering the structures inside the cyst,we suggest that these lesions should be called generically CMMC.Clinical presentation of CMMC is usually a soft cervical mass without marked neurological impairment at the time of diagnosis.External features of the cervical lesion are tubular protuberances at the back of neck covered at the base and most of the cylindrical wall by full thickness skin and on the dome by thick squamous epithelium.The initial neurological examination of a newborn with CMMC is usually considered as normal, but progressive neurological deficits may develop in nontreated children and adults[15–18].Interestingly, none of the patients developed sensory symptoms or deficits,and their bowel and bladder functions were normal[1].These manifestations indicate that the dorsal column function would remain intact despite the fact that the congenital lesions arise from the dorsal cervical cord. Compared with caudal myelomeningoceles,CMMC may have a higher propensity to be associated with other spinal anomalies,such as hydrocephalus,hydromyelia,diaste-matomyelia,lipomyelomeningocele,tethered cord,Chiari malformation,Klippel–Feil syndrome,and thoracic hemi-vertebra,which have been documented in literature[4,13, 19].In our cases,five patients had associated anomalies. Chiari II malformation and hydrocephalus were seen in only one patient.The patients of our series had minimal associated congenital anomalies about which we presume that the Chinese people's idea on pregnancy health and aristogenesis might be an unneglectable reason.What's more,after surgery,the patients were not found to develop late neurological deteriorations in the follow-up.MRI is the ideal noninvasive form of investigation and should be done in all patients both pre-and postoperatively.It can depict fine anatomical relationships at the level of the lesion and can also detect any other spinal cord anomalies[20, 21].CMMC is frequently associated with occult spinal anomalies.This is why there is an emphasis on total spine MRI in patients diagnosed with CMMC.MRI of the whole vertebral column should be carried in all patients before surgical intervention,for failure to appreciate the anatomical details of the lesion and associated anomalies may result in treatment failure,with deterioration in follow-up.Sagittal MRI of majority of cases demonstrates that there is a cystic lesion at the back of neck and a communication between the cyst and the spinal subarachnoid space at this level.The spinal cord in this place is led posteriorly and focally angled backwards,and the subcutaneous portion of the cyst becomes funnel-shaped to enter the spina bifida.The hardy nonleaking coverings of the sac in CMMC allow ample time for preoperative MRI.Consequently,MRI is indispensable for determining the level of CMMC,and MRI of the entire spine is recommended[7,13].The histological features of the sac of CMMC are very similar among all specimens.The sac of CMMC is composed of a CSF-filled cyst,which is the nature of the lesions.The base of the sac is covered by full-thickness skin with normal adnexa;the dome of which is covered by a thickened layer of squamous epithelium[4,5,12], and the sac is lined by arachnoid that is continuous with the intraspinal arachnoid through the fistulous tract.In some cases,the tissue bands are neuroglial stalks consist-ing of aberrant nervous tissue,but in other cases,the tissue bands are fibrovascular stalks composed exclusively of fibrovascular elements[1,4,6,17,22].It is clear that CMMC differs from the common variety of lumbosacral myelomeningocele in the following aspects: First,the sac of CMMC is always covered by full thickness skin at the base and by tough squamous epithelium at the dome,which makes the arachnoid membrane hard to be exposed and CSF leakage very unlikely.In contrast,the cyst wall of lumbosacral myelomeningocele is composed of a layer of very thin delicate arachnoid membrane,is fragile, and is usually accompanied by CSF leakage.Second,the neurological function of a patient with CMMC is normal or near normal caudal to the level of the lesion,whereas,a patient with lumbosacral myelomeningocele usually suffers the loss of neurological function at or below the level of the terminal neural placode.Third,the neuronal content of CMMC is a nearly closed neural tube with a midline gap. There is no neural placode and the morphology of the spinal cord is normal or close to normal.But in a lumbosacral myelomeningocele,the neural content is usually a flattened,exposed terminal neural placode not covered by leptomeninges.Fourth,CMMC is often accom-panied by Chiari II malformations,but not the other anomalies commonly found in conjunction with lumbar myelomeningocele,such as fused thalami,dysgenesis of the corpus callosum,and gyral disorganization[5].Since CMMC is a tethering lesion,all of the published papers agree on the early intervention of this entity, definitely before the onset of any neurological deficits[5, 6,13].We have favored surgery for CMMC patients within 3–6months of birth or at the earliest detection in patients referred after this age.In conclusion,whenever a CMMC is detected—at birth or later in life,prompt treatment is essential to avoid neurologic impairment.As for the surgical treatment for CMMC,simple subcutaneous resec-tion of the CMMC sac along with ligation of the dural fistula no longer has merits.An inadequate surgical technique on untreated cervical cord tethering may lead to late neurological deterioration.Surgical management should include a two-level laminectomy,intradural explo-ration to excise the tissue band tethering spinal cord,andresection of the associated protruding sac.A microsurgical technique should be used to detect any spinal cord tethering or any associated spinal dysraphic abnormalities.At surgery,an effective approach involves the exposure of the spinal cord for at least two vertebral levels in order to have the lesion properly explored.Stalks,bands,aberrant roots,or any other abnormal structures,as soon as they are identified,must be excised flush to the spinal cord.As far as untethering the cord is concerned,unlike the myelome-ningocele in lower locations,preservation of aberrant neural tissues is not recommended,for these tissues have been documented to be nonfunctional[5,6].In our cases,a thorough release of the fibroneural bands and aberrant roots was performed to all,and no neurological deterioration was encountered in any patient.So the surgery for CMMC is not only for cosmetic reasons,but more importantly for prophylactic release of all the tethered cord elements and the prevention of functional loss.The typical manifestation of neurological dysfunction in cases undergoing only extraspinal resection of the sac is typically progressive worsening of motor function in the upper extremities primarily on follow-up[1,5,6,16,17].The mean interval between the time of resection of myelomeningocele sac and the neurological deterioration is reported to be3.6years[5]. To sum up,the key points of optimal treatment for CMMC include an adequate laminectomy;intradural exploration; and resection of all tethering bands and septa.The prognosis of CMMC patient is surprisingly favor-able as compared with that of patients with lumbosacral myelomeningocele in neurologic,orthopedic,and urologic respects.But late neurological deterioration has to be considered in growing children due to retethering,and therefore,regular follow-up is of particular importance. ConclusionsCMMC differs clinically and structurally from lumbosacral meningomyelocele,and it has a more favorable outcome. Patients with CMMC usually have intact neurological function below the lesions.It is recommended that MRI of the whole vertebral column should be carried out preoperatively to identify the internal structures and other associated anomalies.The management strategies of CMMC should be early surgery with standard micro-neurosurgical techniques to prevent the development of neurological defects.The optimal surgical treatment consists of an adequate two-level laminotomy,intradural exploration,and excision of all tethering bands and septa in addition to resection of the sac.The outcome after surgery for CMMC is cheering,as majority of the children have no or minimal neurological deficit after surgery.References1.Sun JC,Steinbok P,Cochrane DD(2000)Cervical myelocystocelesand meningoceles:long-term follow-up.Pediatr Neurosurg33:118–1222.Ankola PA,Fernandes Y,Tunnessen WW Jr(1998)Picture of themonth:cervical myelomeningocele.Arch Pediatr Adolesc Med 152:299–3003.Nishino A,Shirane R,So K,Arai H,Suzuki H,Sakurai Y(1998)Cervical myelocystocele with Chiari II malformation:magnetic resonance imaging and surgical treatment.Surg Neurol49:269–273 4.Steinbok P(1995)Dysraphic lesions of the cervical spinal cord.Neurosurg Clin N Am6:367–3765.Pang D,Dias MS(1993)Cervical myelomeningoceles.Neurosur-gery33:363–3736.Steinbok P,Cochrane DD(1991)The nature of congenitalposterior cervical or cervicothoracic midline cutaneous mass lesions:report of eight cases.J Neurosurg75:206–2127.Erşahin Y,Barçin E,Mutluer S(2001)Is meningocele really anisolated lesion.Childs Nerv Syst17:487–4908.Meyer-Heim AD,Klein A,Boltshauser E(2003)Cervicalmyelomeningocele.Follow-up of five patients.Eur J Paediatr Neurol7:407–4129.Kasliwal MK,Dwarakanath S,Mahapatra AK(2007)Cervicalmeningomyelocele—an institutional experience.Childs Nerv Syst 23:1291–129310.Salomão JF,Cavalheiro S,Matushita H,Leibinger RD,BellasAR,Vanazzi E,de Souza LA,Nardi AG(2006)Cystic spinal dysraphism of the cervical and upper thoracic region.Childs Nerv Syst22:234–24211.Feltes CH,Fountas KN,Dimopoulos VG,Escurra AI,Boev A,Kapsalaki EZ,Robinson JS,Troup EC(2004)Cervical meningocele in association with spinal abnormalities.Childs Nerv Syst20:357–36112.Nishio S,Morioka T,Hikino S,Fukui M(2001)Cervical(myelo)meningocoele:report of2cases.J Clin Neurosci8:586–587 13.Delashaw JB,Park TS,Cail WM,V ollmer DG(1987)Cervicalmeningocele and associated spinal anomalies.Childs Nerv Syst 3:165–16914.Cameron AH(1956)The spinal cord lesion in spina bifida cystica.Lancet271:171–17415.Duprez TP,Laterre EC(1995)Unusual form of closed dysraphismof the cervical spine.Acta Neurol Belg95:42–4316.Wu JK,Scott RM(1990)Myelopathy presenting decades aftersurgery for congenital cervical cutaneous lesions.Neurosurgery 27:635–63717.V ogter DM,Culberson JL,Schochet SS,Gabriele OF,KaufmanHH(1987)“High spinal”dysraphism:case report of a complex cervical meningocele.Acta Neurochir(Wien)84:136–13918.Konya D,Dagcinar A,Akakin A,Gercek A,Ozgen S,Pamir MN(2006)Cervical meningocele causing symptoms in adulthood: case report and review of the literature.J Spinal Disord Tech 19:531–53319.Sulla I,Fagula J,Výrostko J,Kundrát I(1980)Case report ofa patient with Klippel-Feil syndrome and occipital-cervicalmeningocele.Rozhl Chir59:760–76220.Andronikou S,Wieselthaler N,Fieggen AG(2006)Cervical spinabifida cystica:MRI differentiation of the subtypes in children.Childs Nerv Syst22:379–38421.Tortori-Donati P,Rossi A,Biancheri R,Cama A(2001)Magneticresonance imaging of spinal dysraphism.Top Magn Reson Imaging12:375–40922.Steinbok P,Cochrane DD(1995)Cervical meningoceles andmyelocystoceles:a unifying hypothesis.Pediatr Neurosurg 23:317–322。
