Spina bifida literally means “spine in two parts” or “open spine”.
Spinal dysraphism is a term used for a group of disorders
characterized by incomplete fusion or lack of fusion of midline structures during the fourth week of embryogenesis.
Spinal dysraphism can be broadly categorized into open and closed types. In open spinal dysraphism, there is a defect in the overlying skin, and the neural tissue is exposed to the environment. In closed spinal dysraphism, the neural tissue is covered by skin. Closed spinal dysraphisms can be further subcategorized on the basis of the presence or absence of a subcutaneous mass .
Open spinal dysraphism includes- Meningocele
Closed spinal dysraphism includes- Dorsal dermal sinus
Thickened filum terminale
VATER association is typically defined by the presence of a cluster of at least three of the following congenital malformations:
V: vertebral anomalies,
C: cardiac anomalies,
TE: Tracheoesophageal fistula +/- esophageal atresia,
R: renal anomalies,
L: Limb anomalies.
Although diagnostic criteria vary, the incidence is estimated at approximately 1 in 10,000 to 1 in 40,000 live-born .
Ultrasonography(USG) has been used to evaluate the spinal
canal since the 1980s . It is a well-established method of investigating the spinal canal and cord as well as the meningeal coverings in the newborns. In this age group, the incompletely ossified and predominately cartilaginous spinal arches create an acoustic window that permits the transmission of ultrasound beam. Therefore, ultrasound should be considered as the initial imaging modality of choice for investigating the spinal canal in newborns
Spinal development can be summarized in three basic embryologic stages i.e gastrulation , primary neurulation and secondary neurulation.
1. Gastrulation (week 2-3 of embryological development ): There is a conversion of bilaminar embryonic disk to trilaminar disk which consists of ectoderm, mesoderm, and endoderm.
2. Primary neurulation (weeks 3–4 of embryological development) : The notochord and overlying ectoderm interact to form the neural plate. The neural plate bends and folds to form the neural tube, which then closes bidirectionally in a zipperlike manner (Fig. 1). A, Neurulation (closure of neural tube) is process of progression from neural plate to neural groove to neural tube. (Reprinted with permission from Sadler T. Langman’s medical embryology, 5th ed. Baltimore, MD: Lippincott Williams ; Wilkins, 1985:335 )
3.Secondary neurulation (weeks 5–6 of embryological development) : During this stage, a secondary neural tube is formed by the caudal cell mass. The secondary neural tube is initially solid. It subsequently undergoes cavitation to form the tip of the conus medullaris and filum terminale, by a process called as retrogressive differentiation.
Abnormalities in any of these steps can lead to spine or spinal cord malformations .
NEONATAL SPINE SONOGRAPHY:
In neonates with suspected spinal and paraspinal anomalies, magnetic resonance imaging (MRI) remains the imaging gold standard. However, with the advent of new generation of high frequency ultrasound scanners, ultrasonography has recently witnessed a tremendous improvement in the image quality, that has brought its diagnostic value on par with that of MRI in certain conditions. Sonography is easily available, portable, cheap and does not require sedation or general anesthesia. Moreover there are no artefacts seen due to patient movement, cerebrospinal fluid (CSF) pulsation or vascular flow which are factors adversely affecting MR image quality .
In newborns , the spinal arches are predominantly cartilaginous and therefore provide an acoustic window allowing passage of the ultrasound beam. However, in older children, ultrasound suffers from diminished utility due to progressive ossification of the spinal arches. Sonography is a well?established method for investigating the spinal canal, cord, and meningeal coverings and for characterizing nearly all spinal anomalies with high geometric resolution in the neonatal and infantile age groups
INDICATIONS OF SPINAL SONOGRAPHY:
The American Institute of Ultrasound in Medicine (AIUM) guideline lists the following indications for the ultrasound examination of the neonatal spine :
•Lumbosacral stigmata known to be associated with spinal dysraphism
•Evaluation of suspected defects such as cord tethering, diastematomyelia, hydromyelia, and syringomyelia
•Spectrum of caudal regression syndrome (e.g., anal atresia or stenosis; sacral agenesis)
•Visualization of hemorrhagic fluid within the spinal canal in neonates and infants with intracranial hemorrhage.
•Guidance for lumbar puncture.
•Postoperative assessment for cord re?tethering.
Ultrasound is usually not preferred in the assessment of open spinal dysraphism because of risk of infection .
TECHNIQUE OF SPINAL SONOGRAPHY:
Sonography of the spine is performed with a high frequency (7–12 MHz), high resolution linear transducer. It is mandatory to scan in both axial and sagittal planes . The axial scanning can either be performed in a cranial to caudal direction or caudocranial direction. Localization of the conus medullaris is crucial for the detection of low-lying cord or high termination of cord. Location of the conus should be interpreted in relation to the lumbar vertebral bodies. Sagittal scanning should be performed both in the median and paramedian planes.
NORMAL APPEARANCES ON SPINAL SONOGRAPHY:
The spinal cord is seen axially as a round or oval hypoechoic structure with central echogenicity within the anechoic subarachnoid space. Paired dorsal and ventral nerve roots are seen to arise from the cord. The vertebral bodies and arches are seen ventral to the spinal cord as echogenic structures with distal acoustic shadowing. The paravertebral muscles are seen below the level of L2 vertebra.
The cord diameter is variable and is the largest at the cervical and lumbar levels, which are known as cervical and lumbar “enlargements” . These give rise to nerve roots of the respective nerve plexuses. In terms of dorsal/ventral orientation, the cord normally lies a third to half way between the anterior and posterior walls of the spinal canal .
The cervical cord and cranio-cervical junction can be difficult to evaluate on ultrasonography. On sequential scanning from the cervical to lumbar level, the cervical and lumbar enlargements are well visualized. A systematic scanning in both the parasagittal and mid?sagittal planes is required. While the parasagittal image is ideal for the evaluation of the paraspinal structures, the mid?sagittal image is ideal for the evaluation of the cord.
The caudal end of the spinal cord is represented by the conus medullaris and filum terminale. The conus is identified as the tapered distal spinal cord, and its level is assigned according to the adjacent intervertebral disk space or mid?vertebral body .
Vertebral landmarks can be identified by either of the following techniques:
1)Identifying the tip of the lowest rib and the iliac crest which correspond to the levels of the L2 and L5 vertebrae, respectively.
2)Identifying the lumbosacral junction by looking for the first clear angulation in the caudal spine with the L5 vertebral body lying immediately cranial to this level. This method can be fallacious in cases of transitional vertebra.
3)Identifying the coccyx and count cranial to it.
In a healthy newborn, the tip of the conus medullaris is located between L1 and L2 vertebral levels.
The normal cord and nerve roots show pulsatile movements which must be specifically looked for to rule out cord tethering .
Normal sacrum in mid?sagittal scanning:
Sacrum should be evaluated in the sagittal plane for the presence of the spinal dysraphism. Since, te posterior elements of the sacrum are unossified at this age, they appear hypoechoic.
The craniocervical junction can be imaged using the foramen magnum as a sonographic window. It is rarely performed, however it can be used to image the inferior cerebellum and proximal cervical cord .
It is due to incomplete regression of the embryonic terminal ventricle in the conus medullaris. It maybe seen on sonography in children younger than 5 years of age and should not be mistaken for a syrinx .
The so-called filar cyst is an interesting incidental finding that has only recently been studied, probably because of being detected more often with improved sonographic equipment. There is no autopsy description of a filar cyst. This questions its origin and its validity
as an entity Possible explanations for the origin of the
filar cyst include normal arachnoid reflections forming a pseudo-cyst like structure or a true ependyma-lined cystic embryonic remnant disrupted by the act of opening the dura during autopsy.
Regardless of its origin, it is a normal variant that alone has
no known clinical significance and does not require additional imaging . On MRI the filar cyst is less reliably visible than on sonography .Strict imaging criteria for filar cysts should be applied i.e. a location midline, within filum, just below conus; fusiform shape, well-defined, hypoechoic appearance of a simple cyst) to avoid underdiagnosing a true disorder xiii.
3)PROMINENT FILUM TERMINALE
The thickness of normal filum terminale measures 1.5 mm or less . A prominent filum terminale may cause concern when it stands out as particularly echogenic in comparison with other nerve roots. It is distinguished as normal by its thickness and typical midline course .
4)PSEUDOMASS DUE TO POSITIONAL NERVE ROOT CLUMPING
Positional clumping of the nerve roots occurs when an infant is scanned in the decubitus position. Rescanning the child prone will cause the “mass” to disappear as the nerve roots return to their normal position xiv.
On sonography it appears a residual cord like region composed of fibrous tissue extending from a skin dimple to the coccyx. True dermal sinus tracts rarely occur at the tip of the coccyx and are typically found in a more cranial location .
The tip of the coccyx can vary widely in shape, and in some cases may mimic a mass when palpated on physical examinationxv.
Spinal pathologies can be broadly categorized as congenital malformations and acquired diseases. Congenital anomalies are attributed to missteps in embryological development of the spinal cord, which result in a diverse range of pathologies that present as myriad sonographic appearances. On the other hand, acquired intraspinal diseases following birth trauma or intraspinal extension of neurogenic tumors can also be detected with ultrasound x.
On the basis of presence or absence of overlying skin covering, spinal dysraphism is divided into open and closed types. In open spinal dysraphism (OSD) overlying skin covering is absent and the neural elements are exposed to the external environment whereas, in closed type the neural elements have a skin covering. Closed spinal dysraphism (CSD) can be further divided based on the presence or absence of associated subcutaneous mass . OPEN SPINAL DYSRAPHISM
These lesions are not skin covered. Myelomeningoceles constitute ;98% of open spinal dysraphism. In myelomeningocele, there is expansion of the ventral subarachnoid space that displaces the neural placode dorsally resulting in portions of the spinal cord, nerve roots, and leptomeninges lying within the sac; whereas in myelocele, the neural placode remains flush with the skin surface and there is no expansion of ventral CSF space rxvi.
Some authors caution against preoperative imaging for these anomalies owing to risk of infection or injury. However, by observing strict aseptic precautions, including covering the probe with a sterile cover and using sterile gel, proper sonographic examination can be performed using the intact normal skin surrounding the parchment membrane of the lesion as the acoustic window. In addition to local examination, sonography is also useful in recognition of associated malformations such as Chiari II syndrome, tethered cord, hydromyelia/syringomyelia, and arachnoid cyst .
CLOSED SPINAL DYSRAPHISM
The major use of neonatal spinal sonography lies in the subgroup of closed spinal dysraphism. These entities can present with or without a back mass. Those with a back mass include meningocele, lipomyelocele, and lipomyelomeningocele. Closed spinal dysraphism without a back mass includes dorsal dermal sinus, low lying tethered spinal cord, diastematomyelia, filar lipoma, fatty filum terminale. The cutaneous stigma include sacral dimple, hyperpigmentation, sinus, or tuft of hair x.
Meningocele is the herniation of CSF filled meninges through a vertebral defect, which usually does not contain any part of the spinal cord. On sonography, theses appear as anechoic cystic mass, containing no neural tissue. Posterior meningoceles are more common and are mostly found in the lumbar location. Anterior meningoceles are more common in the sacral region and can present as a presacral mass. Lateral thoracic meningoceles may have a syndromic association with neurofibromatosis?1xviii.
These are skin covered closed spinal dysraphisms with a back mass. In both these entities, there is presence of a fatty mass in the subcutaneous tissue. The distinction between the two is established by the location of the lipoma–placode interface. In lipomyelocele, the lipoma–placode interface lies within the spinal canal, whereas in lipomyelomeningocele, there is expansion of the CSF space and the interface lies outside the spinal canal. The lipoma can be echogenic or isoechoic to subcutaneous fat on sonographyxviii.
Myelocystoceles are considered to be a subtype of myelomeningocele characterized by herniation of a dilated central canal through a posterior midline spina bifida defect. They can be subclassified into terminal and nonterminal types. In terminal myelocystocele, there is a skin covered back mass with herniation of meninges through a posterior spinal defect. In addition, there is a terminal syrinx communicating with the spinal central canal. In nonterminal myelocystocele, only the dilated central canal herniates through a posterior defect xii.
CLOSED SPINAL DYSRAPHISM WITHOUT A BACK MASS
In this subcategory of closed spinal dysraphism, the neural tissue is covered by the skin without any associated subcutaneous massvii.
SPINA BIFIDA OCCULTA
This entity is characterized by the variable absence of several neural arches and various cutaneous abnormalities such as lipoma, hemangioma, cutis aplasia, dermal sinus, and hairy patch; it is often associated with low?lying conus and other spinal cord anomalies xii.
FATTY FILUM AND FILAR FIBROLIPOMA
Fatty filum and filar lipomas occur due to persistent or de?differentiated fatty tissue secondary to spinal cord canalization anomalies xvi. Minimal fat in filum (fatty filum) is of no clinical significance as long as it is an isolated finding in a normal?sized filum (;2 mm)viii.
When sonography depicts an echogenic fatty mass causing filum terminal thickening of ;2 mm, it is referred to as filum terminale lipoma. This is a clinically significant disorder as it may be associated with myelomeningocele, tethered cord, and syringohydromelia, all of which can be easily diagnosed on sonography xi.
TIGHT FILUM TERMINALE SYNDROME:
Incomplete involution of the distal spinal cord during embryogenesis leads to abnormal thickening of the filum terminale. Tight filum terminale syndrome is always associated with tethering of the spinal cord and an abnormally positioned conus medullaris below the L2?3 vertebral level .
DORSAL DERMAL SINUS
Dorsal dermal sinus refers to an epithelium?lined tract that extends from the spinal cord, cauda equina, or arachnoid to the skin x. It usually manifests with cutaneous stigmata and is mostly found in the lumbosacral region in the midline . The entire tract can be visualized on spinal ultrasound. In the subcutaneous tissues, it is seen as a minimally hypoechoic tract within the subcutaneous fat; on the other hand, in the CSF filled subarachnoid space, it is easily visualized as a linear echogenic structurex.
Incomplete regressive differentiation and failed involution of the terminal cord results in abnormal dorsal fixation of the spinal cord adjacent to the vertebral arches.
In neonates, tethered cord is diagnosed on ultrasonography by an abnormally dorsi?fixed spinal cord in the prone position, presence of a low?lying conus medullaris (below the L2–L3 disk space), absence of normal pulsatile motion of the cord and nerve roots, and associated filum terminale thickeningx.
This disorders can result from abnormal midline notochordal integration resulting in split cord malformation or neuroenteric cyst vii.
Split cord malformation:
Split cord malformation/diastematomyelia usually presents as a sagittal cleft in the thoracolumbar spinal cord, resulting in two hemicords (usually asymmetric), which generally reunite caudal to the cleft. Each hemicord has its own central canal and separate dorsal and ventral nerve roots. Diastematomyelia is of two types; either having a separate dural sheath for each cord or having a single sheath. These may be separated by a bony bar, cartilaginous, or fibrous band.
Axial plane USG demonstrates both hemicords and echogenic spur in cross?section, each with a central canal and ipsilateral nerve roots. In addition, commonly associated malformations such as tethered cord and syringohydromelia (which must be specifically looked for) are also easily demonstrated on spinal ultrasonography xii.
This is a complex dysraphism where there is a mucin secreting epithelium?lined cyst located in the posterior mediastinum with an associated vertebral segmentation anomaly. They often have a communicating tract with an intraspinal component of the cyst. The cyst shows a thick wall with alternate echogenic and hypoechoic layers which is known as a gut signature. The intraspinal component may be small and difficult to visualize on ultrasound alonexii.
CAUDAL REGRESSION SYNDROME:
Caudal regression syndrome is attributed to abnormal mesodermal formation of the caudal cell mass x. The grade of deformity can vary from minimal to severe regression of the coccyx, sacrum, and lumbar spine, which consequently alters clinical presentation and sonographic appearances. On spinal USG, imaging appearance may comprise either a blunt, deformed conus medullaris that terminates above the normal level or an elongated conus which is tethered by a thickened filum terminale or intraspinal lipoma and ends below L1xii.
Two types are described:
Type 1 features a foreshortened terminal vertebral column, high?lying wedge?shaped conus termination.
Type 2 is a low?lying tethered spinal cord.
Radiological assessment should be done at the earliest depending on the clinical condition. Plain X-rays reveal the skull defects, spine deformities and bony anomalies. MRI is the investigation of choice to study the neural tissue abnormalities and also to assess the severity of hydrocephalus and Chiari malformation. However, ultrasonography can be used to obtain quick information regarding hydrocephalus.
Management of these children needs a multidisciplinary approach. Complete clinical evaluation and appropriate investigations are necessary. Parents need to be counseled and informed regarding the immediate as well as long-term management strategy.
The aim of surgery is to free the placode from the surrounding abnormal skin and reposition it into the spinal canal with reconstruction of the dura and coverings to prevent CSF leak and infection. The surgical technique depends on the size and the level of the lesion. The help of pediatric, orthopedic and plastic surgeons may be necessary. The role of fetal surgery for myelomeningocele is yet to be provenxxii.
REVIEW OF LITERATURE:
Spinal dysraphism refers to abnormalities with imperfect fusion of the midline neural and bony structures. It is the most common congenital central nervous system abnormality, with myelomeningoceles occurring in up to 2 per 1000 live births in some studies.
In 1940 , the diagnosis of spinal dysraphism was done with the help of radiographs and myelographic study in suspected case of dysraphism . Over the years , it has proven to cause difficulty in multiple ways. Computed tomography on the other hand exposes the young childrens for hazardous radiation exposure and inability for the child to lie still throughout the scan , which further requires general anaesthesia . Although the MRI is a gold standard modality for suspected case of spinal dysraphism. Ultrasonography has proven to be the initial screening modality for spine due to it wide availability , non-invasive and cost effective.
In 1982 , J H Miller et al in their study used automated water path ultrasound scanning technique to examine the spine .Studied also included those with minimal cutaneous stigmata. The spinal abnormalities demonstrated were meningocele, myelomeningocele, and spinal lipoma. Screening of kidneys and brain was also done to assess associated anomalies. Total of 15 children were studied in the age group 1 day to 8 years old. In which 10 children’s were diagnosed meningoceles (sac were unilocular in 8 and multilocular with septa in 2 ). Two of these childrens with meningoceles had mild dilatation of ventricles, however the intracranial anatomy was normal. Another two children had myelomeningocele (In which one of the child was detected with cerebral dysgenesis associated with Arnold-Chiari malformation). A severe gibbous deformity was seen in one children with severe myelomeningocele. Renal abnormalities (such as hydronephrosis) were seen in 5 children’s with myelomeningocele. Rest two had spinal lipoma. One child with minimal cutaneous stigmata on lower back was detected as occult meningocele with associated defect in posterior element at lumbar level. In their study , by using the automated water bath ultrasound helped for diagnosis in the dysraphism , limiting the radiation (than radiography of lumbar series) and the cost. Also it was their believe to use this technique in initial diagnostic modality in evaluation of minimal cutaneous stigmata and associated renal or intracranial pathology. It also concluded that ultrasound examination of the neural axis should play an important role in evaluation of children with spinal dysraphism
William Scheible et al , in March 1983 used high resolution real-time sonography (I0-MHz transducer) for occult spinal dysraphism. Over a period of 4 years 34 infants with some cutaneous lesion over a lumbosacral region and but no neurological deficit were studied. In the first case , one day old male infant presented with cutaneous stigmata (aplasia cutis in midline in lumbosacral region). After real time ultrasound , tethered filum was diagnosed and post operatively small dorsal lipoma was removed from the tethered filum .
In second case , 12 week old female infant (congenitally cataract and microcephalic – mother had vaginal herpes) had a hemangioma over the lower back . On ultrasound distal cord did not pulsate and seen ending near the hemangioma. On surgery , it was confirmed that the fibrous stalk was seen extending from the filum to the hemangioma which lead to the tethering of the cord. The last case was about a full term male infant presented with rigid, paralytic left club foot and muscular atrophy of the left lower leg. On ultrasound intramedullary lipoma was diagnosed. Remaining of the 31 cases were not mentioned in the case description or in conclusion.However, this study has shown that lack of typical pulsatile cord motion which is an important feature in patients with a tethered cord .
Fred J. Epstein et al, in 1983 using the real time ultrasound (7.5 MHz) studied 16 patients in which 10 were control (suspected renal problems) and 6 were suspected as spinal dysraphism .
In their study 13 patients revealed the tip of the conus medullaris was identified in the mid lumbar canal and was considered to be within normal limits. In the three infants with a soft-tissue mass overlying the lumbosacral spine, the sonogram showed the cord in the lumbosacral canal, and the normally tapered conus medullaris was not identified. The cord was dorsally placed in the canal and a soft-tissue mass intervened between it and the subcutaneous tissue. In one patient, a subcutaneous fluid collection was also seen adjacent to a fatty mass, which proved to be a lipomeningocele. Surgery, performed in three infants, revealed lipoma to be the major tethering lesion. Their studied suggested two criteria to diagnosis the tethered cord, first is the inability to visualize the normal tapered conus medullaris and visualization of the spinal cord in the lumbosacral spinal canal. In addition , presence of soft tissue mass in the lower end of the cord and widened dural sac also aids to diagnosis of tethered cord. They concluded the high resolution , real time sonography is safe and rapid technique for screening the infants for dysraphism .
Vesna Martich Kriss et al, in period of three years (in December 1998) assessed high-risk cutaneous stigmata on sonography in 207 neonates with 216 cutaneous stigmata (9 infants were having multiple cutaneous stigmata). 16 of 207 infants had spinal dysraphism. In addition 180 dimples and 36 other cutaneous stigmata such as hemangioma , hairy patches were seen. 14 out of the other 36 were positive for spinal dysraphism. 6 of the 9 infants with multiple cutaneous stigmata were positive. Their study concluded that the simple midline dimples were the most commonly encountered dorsal cutaneous stigmata in neonates and indicate low risk for spinal dysraphism. Atypical dimples are associated with a high risk for spinal dysraphism. In addition , ultrasound is safe and non-invasive technique for infants upto 3 months old (further due to ossified posterior elements the cord is not visualized in 3 months and above) .
Charles M. Glasier et al, for a period of two years in 1990 performed ultrasound on 26 newborns with spina bifida (especially diastematomyelia) , prior to initial surgical repair of the neural tube defects , also to measure the cord thickness and to determine the contents of the closed defects. Out of 26 myelomeningocele (7 babies concomitant anomalies were found ), 2 were found to have diastematomyelia, 3 had dural fat deposits and 2 had hydromelia. The cord thickness was measured in anteroposterior diameter at C5-C7 , in mid thoracic level where the cord was easily visualized and at L1-L2 level. The cord thickness were taken in order to see the association with lower limb extremity function. Their study concluded the sonographic finding correlated with the neurological function i.e a very thin (less than 2 mm) hyperechoic distal cord were seen in infants with extreme lower limb function. In addition , the ultrasound is invasive modality for screening such cases .
In 1992, Korsvik HE et al , studied 15 children’s with suspected case of occult dysraphic lesions (ODL )in which 7 were positive (5 neonates and 2 infants). Sonographic findings suggestive of an ODL include low position of the conus, non-tapered bulbous appearance of the conus, dorsal location of the cord within the bony canal, solid or cystic masses in the distal canal or soft tissue of the back extending toward the canal, patulous distal thecal sac, and thick filum . Physical findings suggestive of ODLs were lumbosacral skin dimples, lumbosacral masses, lower extremity weakness, and an extra appendage arising from the back. These were examined with ultrasound and correlated with those on magnetic resonance (MR) images. Their studied concluded that high resolution sonography can help in diagnosis in suspected case of ODL in neonates and infants before the ossification of the posterior elements. However , they also mentioned that MR imaging is most useful when sonographic findings are abnormal or equivocal or when normal skeletal maturation limits sonographic visualization of the intracanalicular contentsvi.
In year 2001; Dick EA et al assessed the diagnostic value of spinal ultrasound in cloacal exstrophy, a caudal malformation which is associated with spinal dysraphism, and to assess the prevalence of spinal dysraphism in cloacal exstrophy by spinal ultrasound. Ten infants (under 1 year old) with cloacal exstrophy. Three patients also had a magnetic resonance imaging (MRI) examination. Ultrasound and MRI images were reviewed and correlated. Nine of 10 patients had no external signs of spinal dysraphism. One patient had a clinically apparent myelomeningocele. Five of 10 patients (50%) had spinal dysraphism on ultrasound: there were two patients with a low cord, two with tethered cords and a lipoma, and one patient with tethering and a myelomeningocele. Thus, in four of these five patients spinal dysraphism was occult. In a small number of patients (n = 3) MRI was also performed-in these cases the MRI and ultrasound appearances correlated, however MRI was not performed in those patients in whom spinal ultrasound was normal. Their study also concluded that the spinal ultrasound should be the first investigation in all babies with cloacal exstrophy to diagnose occult and non-occult spinal dysraphism. Advantages of spinal ultrasound include ease of examination, production of high quality multi-planar images and the facility for portable imaging at the bedsidexviii.
Kuang-Lin lin et al in 2002 investigated the correlation between cutaneous lesions, patent dermal sinus tracts, and spinal dysraphism and their complications by sonography. Five patients (3 female and 2 male) with spinal patent dermal sinus tracts were studied. They used a 7-MHz linear transducer with a two-dimensional real-time sonographic system to insonate and obtain transverse and longitudinal views of the spinal cord and subcutaneous area, extending from the cervical cord to the sacral areas. Subsequently, we performed spinal magnetic resonance imaging in every patient to confirm the diagnosis and to evaluate the intraspinal conditions. The associated central nervous system anomalies and complications were tethered cords (n = 5), dermoid cysts (n = 3), lipoma (n = 2), central nervous system infections (n = 2), and syringomyelia (n = 1). The outcomes were better in those who received surgical intervention before they were infected. Early detection of spinal patent dermal sinus tracts and related anomalies was accomplished with spinal sonography and allowed for prophylactic treatment (e.g., early surgical intervention) before the onset of neurologic deficits .
J. A. Hughes et al in 2002 (period of 31 months) conducted study for evaluation of spinal dysraphism in 85 patients ( neonates and infants) and to determine agreement with MRI findings. 85 patients had lumbosacral mass or cutaneous stigmata or known dysraphism or abnormal radiographs or previously repaired open spinal dysraphism. Out of 85 patients , 74 were reported normal and 11 were positive for dysraphism on ultrasound. All these 11 patient with 4 patient (from the 74 were normal) were followed up on MRI (due to presence of neurological deficits , cutaneous stigmata and spinal dysraphism). In which 3 (out of the 15)were normal and 12 (out of 15 )were abnormal on MRI. When these were compared with the ultrasound findings , 6 out of 15 had full agreement , 7 had partial agreement and 2 had no agreement. This is because the ultrasound failed to visualize four of four dorsal dermal sinuses, three of four fatty filum terminales, one of one terminal lipoma, two of four partial sacral agenesis, three of four hydromyelia and one of 10 low-lying cords. Agreement between ultrasound and MRI was good, particularly for the detection of low-lying cord (90%). An ultrasound study with normal findings is believed to exclude an OSD, and no further examination is warranted. Therefore their study recommends ultrasound as a first-line screening test for OSD .
David Guggisberg et al, in year 2004 (over a period of 9 years) retrospectively studied 54 children (37 girls and 17 boys) with midline cutaneous lesion. Ultrasound examination were performed in all the patients. Occult spinal dysraphism was detected in 3 of 36 (out of 54) patients were presented with isolated lumbosacral lesion and 18 (out of 54) were presented with 2 or more lesions. 14 out of )51 patients underwent MRI.
Robinson AJ et al in 2005 studied the value of ultrasonic examination of the lumbar spine in infants with specific reference to cutaneous markers of occult spinal dysraphism. Over a 10-year period a total of 223 infant lumbar spines were scanned, for various clinical indications. Forty of these patients had already had abnormalities detected antenatally by foetal ultrasonography. One hundred and eight-three patients had abnormalities detected on postnatal clinical examination; most of these had various cutaneous markers, some had other congenital abnormalities. There were a total of 29 patients with dysraphism; 24 were detected antenatally and five postnatally. Of the five, two had two or more cutaneous markers and three had anorectal anomalies. All 86 of the patients with simple sacral dimples, pits or sinuses were normal. As an isolated abnormality, simple dimples or pits are not useful markers of spinal dysraphism.
Chih-Kang Chang et al in 2008, did an retrospective study in their private multidisciplinary based clinic which included 190 patients (91 patients had myelomeningocele and 99 patients had lipomeningomyelocele ). 78 patients out of 190 were undertaken for this study and the remaining were lost of medical records. Subjects with myelomeningoceles had more severe neurologic involvement, poorer ambulation outcome and bladder dysfunction (i.e 1 Arnold-Chairi malformation , 22 Scoliosis , and 57 with bladder dysfunction). Their study correlation test revealed that the level of ambulation was negatively influenced by a higher neurologic level and various orthopedic deformities. Their study had several limitation such as lack of information conveyed on the telephone and that many subjects in their original samples were not included in their study sample. They believed that their study can be used for further study designs especially the prospective studies with or without focusing on specific issues .
In year 2009, over a period of 4 years Sardana K et al investigated 180 patients with dorsal midline stigmata (evaluated clinically ,radiographs and ultrasound imaging modality). They assessed the frequency and type of cutaneous stigmata ( in different forms of spinal dysraphism) .In addition , find the role of ultrasonography and/or magnetic resonance imaging in diagnosing spinal dysraphism at two pediatric dermatology tertiary care centers. Subsequently surgical interventions were planned in conjunction with neurosurgery and orthopedic specialists. On examination, 245 (4.2%) had 285 cutaneous stigmata. Of the 180 patients evaluated with radiography, ultrasonographic examination and magnetic resonance imaging, 50 patients (28%) had spinal dysraphism (with 64 cutaneous stigmata). The most common stigmata associated with occult spinal dysraphism were lipoma (10) and dimples (12) and in open spinal dysraphism lipomeningomyelocoele (10) and meningomyelocoele(10).Statistically,lipomeningomyelocoele/myelomeningocoele, atypical dimples and port-wine stains were most associated with spinal dysraphism (p < 0.001). In 80 children less than 6 months of age, radiography with ultrasonographic examination revealed an SD in 16, while magnetic resonance imaging was diagnostic in four cases. Ultrasonographic examination performed fairly well in children less than 6 months and in cases of flat cutaneous stigmata it missed only 5% of cases, but in cases with bulky overlying masses (lipoma, hemangioma) it missed 15% of cases . Their study was also compared with Vesna xxxii .
Chern JJ et al in 2012 correlated lumbar ultrasound (LUS) and MRI findings in patients suspected of having occult spinal dysraphism (OSD). Over a 5-year period, 1273 consecutive infants underwent an LUS study at a major pediatric tertiary referral center. Of these, 106 patients had abnormal LUS findings suggestive of an OSD, and 103 underwent subsequent MRI studies. The anatomical descriptions of the 2 studies were compared for agreement. The average age of the infants was 34 days at the time of the LUS study; OSD was suspected in these patients because of the presence of cutaneous stigmata and congenital defects. The most common anatomical descriptions from the LUS study included a thickened or fatty filum (32 cases), filum cyst (11 cases), and presence of a terminal ventricle or syrinx (9 cases). Using MRI findings as the standard reference, the sensitivity of LUS in detecting a thickened or fatty filum was 20%. The sensitivity of detecting an abnormal conus level at or below L-3 was 76.9%. In the patient population chosen to undergo LUS studies, abnormal findings had poor sensitivity at detecting anatomical findings consistent with OSD . Their study was also compared with Vesnaxxxii , sardanaxxxix and Davidxxxvii.
Beverly G. Coleman Jill E et al, helped in diagnostic features of spina bifida in Role of Ultrasound in 2014 show SB and MMC themselves pose a diagnostic and therapeutic challenge, they can be components of more complex syndromes, associations or complexes. For this reason, a key aspect of evaluation of the fetus with an MMC is to perform a thorough and detailed examination of the entire fetus. Knowledge of what to expect can help increase the detection of associated abnormalities. Though this review has concentrated on the imaging aspects of evaluation, the obstetrical, surgical and genetic aspects are also important and help shape the manner inwhich imaging is performed.
Jennifer N. Kucera et al. conducted the study on simple sacral dimple: diagnostic yield of ultrasound in neonates in June 2014. The high-resolution ultrasound affordable today with state-of-the-art equipment allows us to make a very accurate diagnosis of MMC, including details related to the entire fetal central nervous system. Ultrasound can accurately localize the site of the osseous and soft tissue defects. Additional findings of kyphosis, scoliosis and anomalous vertebrate and associated conditions such as cervical syrinx can be identified. The state of the intracranial structures, including the presence or absence of ventriculomegaly and hindbrain herniation, as well as unexpected complications such as intracranial haemorrhage can be diagnosed. The information provided by ultrasound plays a crucial role, now more than ever, in patient counseling and pregnancy management.
Narges Afzali et al in 2016 investigated spinal cord abnormalities in newborns with sacral pit via ultrasound examinations. In the descriptive study, 3071 infants born at 34-42 weeks of gestation were studied in hospitals affiliated to Islamic Azad University of Mashhad, Iran during 2014-2015. Information including age, sex, and birth weight was recorded in a questionnaire. Infants with a sacral pit underwent ultrasonography; spinal shape and mobility in these infants were compared with their healthy counterparts. Based on the findings, 1.6% of the studied infants were born with a sacral pit. The weight and age were not significantly different between healthy neonates and those with a sacral pit. The prevalence of sacral pit was higher in female cases (54.2%), although there was no significant difference between the genders. Ultrasound examination of the spinal cord revealed its normal position and motility in all newborns with a sacral dimple. The present results showed the normal shape and motility of the spinal cord in newborns with a sacral pit.
Dhaval Durlabhbhai Dhingani et al in 2016 evaluated Spinal dysraphisms using USG and MRI and correlated imaging findings with operative findings in patients undergoing surgery. 38 cases of both sexes and below 12 years of age with spinal dysraphism were studied. USG was performed in 29 cases where acoustic window was available for proper evaluation. MRI was performed in all cases. USG findings were compared with MRI findings and operative follow up was taken in 23 cases who underwent operative management. 39.47 % cases were male and 60.53 % cases were female. Neonatal period was the most common presenting age group. Closed spinal dysraphism (63.16%) was more common than open (36.84%). 79.31% cases showed full agreement between spinal USG and MRI examinations and 6 out of 20.69% showed partial agreement. On operative correlation, USG findings were confirmatory in 91.30% cases and MRI findings were confirmatory in 100% cases. USG can be used as the initial modality for evaluation of spinal dysraphism as well as for screening of suspected cases. MRI is indicated to confirm abnormal USG findings, which shows all concurrent abnormalities and also provides additional anatomical details relevant to surgical planning.
(shift this to end — )Now , the estimated incidence of spinal dysraphism is about 1–3/1000 live births. The prevalence of spinal dysraphism has declined in the last few decades due to better maternal nutrition , folic acid supplementation, improved antenatal care, high-resolution ultrasound for prenatal screening and biochemical markers
The present cross sectional observational study was conducted to evaluate presence of spinal anomalies in neonates by USG.
The study was conducted during September 2016 to August 2018 on patients under 28 days of age of either sex, presenting with congenital spinal abnormalities in the Department of Radio diagnosis and Imaging Bharati Vidyapeeth Deemed to be University Medical College Hospital and Research center, Pune. A total sample size of 70 patients , age under 28 days of age and both sexes, with signs and symptoms of congenital spinal anomalies (overt and occult spinal dysraphism) and neonates with VATER association were included in the study. The study was undertaken after ethical committee approval and a written informed consent from the parents.
In the present study, the maximum numbers of patients were in the age group of 0-5 days (62.86%), followed by in 21-30 days (15.71%). The mean age among the distribution of cases was 8.76 ±7.72 days.
Out of 70 patients, (12 )44 males (62.86%) were the most affected when compared to females (37.14%) and male to female ratio was 1.69:1. There was male predominance observed in our study.
The spinal dyspharism among patients showed that majority of patients had followed by meningomyelocoele (20%), tethered cord (16%), diastematomyelia (8%), lipomyelomeningocele (8%) and Syrnix (4%). CRS was observed in one (4%) patient.
The commonest anomalies was seen in male were tethered cord, diastematomyelia and lipomyelomeningocele. Cutaneous swelling at the back was the most frequent presentation. Ultrasound helps in characterization of the contents within and hence helpful in screening of the neonate. The lumbar region was the commonest site of spinal dyraphism. The multiple associations seen with each anomaly could be characterized.
The dysraphic features in patients with abnormalities could be detected on ultrasonography. It was helpful for screening for the cases with the help of ultrasonography screening.
It was observed that among 70 patients majority of them had abnormal USG findings in spine (35.71%) as compared to brain (10%) and KUB (24.29%) The majority of patients had abnormal USG findings in spine in 0-5 days (72%). There was no statistical significance with respect to age for USG findings among patients. (P>0.05)
It was observed that majority of patients had positive USG findings in spine among males (52%) as compared to females (48%). There was no statistical significance with respect to sex for USG findings among patients. (P>0.05)
As compared to study conducted by Vesna Martich Kriss et al, 16 cases were positive for spine pathology in 207 patients. Similar study was conducted by Jennifer N kucera in 2014 had 133 cases over a period of 6 years showed positive in 330 cases.
In present study of 70 patients , 23 cases were positive for spinal pathology out which had 6 patients presented with skin markers.
It was estimated that upward of 86% of spinal dysraphisms were associated with overlying cutaneous stigmata. In a large study of nearly 4000 infants, Kucera et al, estimated that cutaneous findings potentially associated with occult spinal dysraphism (OSD) are present in upto 7.2% of healthy children; of these cutaneous findings,74% were sacral dimples.
This was similar to other studies that reported an estimated incidence of sacral dimples in 4% of newborns. Early identification of OSD is paramount in order to obtain appropriate neurosurgical evaluation and management to prevent neurological sequelae. However, even in the presence of a sacral dimple true spinal anomalies are rare, ranging from 0.13% to 1% in existing studies. Our study demonstrates similar findings; among 70 neonates, who were screened, only 5 neonates required surgical intervention.
The guidelines had been developed to help clinicians to determine which examination findings warrant further workup; concerning findings include dimples located superior to the natal cleft or more than 2.5 cm from the anal verge, dimples larger than 5 mm in diameter, multiple dimples, or dimples associated with other cutaneous stigmata, including hypertrichosis, hemangiomas skin tags, or duplicated gluteal clefts.
Several studies had indicated that simple, solitary dimples located within the gluteal cleft without evidence of drainage (to indicate a dermal sinus) do not require further evaluation, as they are not typically associated with underlying spinal dysraphism.
Harada et al, on the other hand, identified 14 of 103 children (16.7%) with intragluteal dimples as having fibrolipomas of the filum terminale. These lesions were associated with deep dimples or the presence of additional congenital anomalies. The study did not discuss which lesions required intervention or further management.
In present study, 72% who underwent a screening spinal US related to the presence of a sacral dimple met criteria for screening based on current guidelines. One of these neonate had a tethered cord requiring surgical intervention.
In a study by Chern et al, which involved a retrospective study of 1116 neonates undergoing lumbar ultrasonography for OSD screening, there was a significantly higher positive predictive value for detecting OSD among neonates images due to the presence of congenital anomalies compared with those imaged for suspicious cutaneous findings alone (28% vs 5.9%). The positive predictive value for those neonates with congenital anomalies versus cutaneous stigmata going on to require neurosurgical intervention was similarly higher for those with congenital anomalies (6.7% vs 0.85%). This suggests that neonates with congenital anomalies are at higher risk for spinal dysraphism compared with the general population and may require separate screening guidelines.
Similarly, Harada et al, described many neonates in their study who had deep sacral dimples or “other congenital anomalies” who were diagnosed with spinal fibrolipomas. Larger studies are needed to further assess the possible correlation between certain anomalies and spinal dysraphism. Additionally, the best initial imaging modality may differ for neonates with certain anomalies. For example, Scottoni et al, found that neonates with imperforate anus tended to have increased risk of false-negative ultrasonography at their institution.
Several neonates in this study had a sacral dimple with associated cutaneous findings. Among the 19 neonates with a dimple , 4 were found to have filar cysts and none required neurosurgical intervention. Similarly, all neonates with a dimple had a normal screening. (** add )Therefore, the overall incidence of spinal dysraphism in our study was low for all types of cutaneous findings.
The present study indicates the key findings that the relative rarity of clinically significant findings on ultrasonography. Among 70 infants in our study who underwent evaluation with spinal ultrasonography in accordance with guidelines, only 5 neonates required neurosurgical intervention.
The limitations of present study were, first, it does not include neonates who were initially evaluated with MRI, but rather only includes those neonates initially imaged with spinal ultrasonography and a small sample size which may cause bias in the study.
Ultrasound of the spinal cord and spinal canal is a reliable method of examining newborns .
Early performed ultrasound allows an exact examination of the spinal canal and its contents and enables one to rule out significant pathologic conditions.
In addition, in complex spinal malformations, the role of US is to allow detection of associated anomalies.