Neonatal -Infant Spine Ultrasound

AIUM Practice Parameter for the Performance of an

Ultrasound Examination of the Neonatal Spine

© 2011 by the American Institute of Ultrasound in Medicine

Parameter developed in collaboration with the American College of Radiology,

the Society for Pediatric Radiology, and the Society of Radiologists in Ultrasound.

neonatalSpine.qxp_1115 12/1/15 3:20 PM Page 1

The American Institute of Ultrasound in Medicine (AIUM) is a multidis-

ciplinary association dedicated to advancing the safe and effective use

of ultrasound in medicine through professional and public education,

research, development of parameters, and accreditation. To promote

this mission, the AIUM is pleased to publish, in conjunction with the

American College of Radiology (ACR), the Society for Pediatric

Radiology (SPR), and the Society of Radiologists in Ultrasound (SRU),

this AIUM Practice Parameter for the Performance of an Ultrasound

Examination of the Neonatal Spine. We are indebted to the many

volunteers who contributed their time, knowledge, and energy to

bringing this document to completion.

The AIUM represents the entire range of clinical and basic science

interests in medical diagnostic ultrasound, and, with hundreds of

volunteers, the AIUM has promoted the safe and effective use of ultra-

sound in clinical medicine for more than 50 years. This document and

others like it will continue to advance this mission.

Practice parameters of the AIUM are intended to provide the medical

ultrasound community with parameters for the performance and

recording of high-quality ultrasound examinations. The parameters

reflect what the AIUM considers the minimum criteria for a complete

examination in each area but are not intended to establish a legal stan-

dard of care. AIUM-accredited practices are expected to generally fol-

low the parameters with recognition that deviations from these param-

eters will be needed in some cases, depending on patient needs and

available equipment. Practices are encouraged to go beyond the

parameters to provide additional service and information as needed.

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www.aium.org

©2011 American Institute of Ultrasound in Medicine


I. Introduction

The clinical aspects contained in specific sections of this parameter (Introduction,Indications/Contraindications, Specifications of the Examination, and EquipmentSpecifications) were developed collaboratively by the American Institute of Ultrasound inMedicine (AIUM), the American College of Radiology (ACR), the Society for PediatricRadiology (SPR), and the Society of Radiologists in Ultrasound (SRU). Recommendationsfor physician requirements, written request for the examination, procedure documentation,and quality control vary between the 4 organizations and are addressed by each separately.

This parameter has been developed to assist practitioners performing a sonographic examina-tion of the neonatal and infant spine. In some cases, an additional or specialized examinationmay be necessary. While it is not possible to detect every abnormality, following this parame-ter will maximize the detection of abnormalities of the infant spine. Sonographic examinationof the pediatric spinal canal is accomplished by scanning through the normally incompletelyossified posterior elements. Therefore, it is most successful in the newborn period and in earlyinfancy. In infants older than 6 months, the examination can be very limited, although the levelof termination of the cord may be identified.

In experienced hands, ultrasound imaging of the infant spine has been shown to be an accurateand cost-effective examination that is comparable to magnetic resonance imaging for evaluat-ing congenital or acquired abnormalities in the neonate and young infant.

II. Qualifications and Responsibilities of Personnel

See www.aium.org for AIUM Official Statements including Standards and Guidelines for theAccreditation of Ultrasound Practices and relevant Physician Training Guidelines.

III. Indications/Contraindications

A. IndicationsThe indications for sonography of the neonatal spinal canal and its contents include but are not limited to1–8:

1. Lumbosacral stigmata known to be associated with spinal dysraphism, including but not limited to:a. Midline or paramedian masses;b. Skin discolorations;c. Skin tags;d. Hair tufts;e. Hemangiomas;f. Pinpoint midline dimples; andg. Paramedian deep dimples;

2011—AIUM PRACTICE PARAMETER—Neonatal Spine

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2. The spectrum of caudal regression syndrome, including patients with sacral agenesis and patients with anal atresia or stenosis;

3. Evaluation of suspected defects such as cord tethering, diastematomyelia, hydromyelia,and syringomyelia;

4. Detection of sequelae of injury, such as:a. Hematoma after spinal tap or birth injury;b. Sequelae of prior instrumentation, infection, or hemorrhage; andc. Posttraumatic leakage of cerebrospinal fluid (CSF);

5. Visualization of fluid with characteristics of blood products within the spinal canal inpatients with intracranial hemorrhage;

6. Guidance for lumbar puncture9; and7. Postoperative assessment for cord retethering.10

Infants with simple, low-lying sacrococcygeal dimples typically have normal spinal contents;for them, the examination has a low diagnostic yield.3,7 On the other hand, atypical dimples,such as those larger than 5 mm, located greater than 2.5 cm above the anus, or seen in combi-nation with other lesions, are at higher risk of occult spinal dysraphism.3 A sacral dimple or con-genital sinus that is leaking CSF will need further assessment with magnetic resonance imag-ing, and sonography is therefore not a mandatory first examination in this circumstance.

B. Contraindications1. Preoperative examination in patients with open spinal dysraphism; and2. Examination of the contents of a closed neural tube defect if the skin overlying the

defect is thin or no longer intact.

IV. Written Request for the Examination

The written or electronic request for an ultrasound examination should provide sufficientinformation to allow for the appropriate performance and interpretation of the examination.

The request for the examination must be originated by a physician or other appropriatelylicensed health care provider or under the provider’s direction. The accompanying clinicalinformation should be provided by a physician or other appropriate health care provider famil-iar with the patient’s clinical situation and should be consistent with relevant legal and localhealth care facility requirements.


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V. Specifications of the Examination

The examination should be performed with the infant lying in the prone position, although thestudy can also be done with the patient lying on his or her side when necessary. A small bolster,such as a rolled blanket, may be placed under the lower abdomen/pelvis to help position thepatient. The knees may be flexed to the abdomen to allow adequate spacing of the spinousprocesses and visualization of the spinal canal contents. An infant who has recently been fedwill generally lie quietly during the examination. If feeding is not possible, a pacifier dipped inglucose solution will often be helpful in keeping an infant still for an optimal examination. It isimportant to note that infants, particularly if not full term, have difficulty maintaining normalbody temperature. Therefore, the examination should be performed in a warm room, and thecoupling agent should be warmed.

The cord should be assessed in the longitudinal and transverse planes, with right and leftlabeled on transverse images. The examination may be limited to the lumbosacral region inspecific cases, such as in patients being evaluated for a sacrococcygeal dimple or in thosepatients being scanned to look for the presence of hematoma after an unsuccessful or traumat-ic spinal tap. The entire spinal canal, from the craniocervical junction to the coccyx, may beincluded in appropriately selected cases.

The normal cord morphologic characteristics and the level of termination of the conus shouldbe assessed and documented. To do this, the vertebral body levels need to be accurately iden-tified and numbered. Once the vertebral bodies are clearly numbered, the level of terminationof the conus can be determined. In normal patients, the conus should lie at or above the L2 toL3 disk space.8,11–14 In fetuses and extremely preterm neonates, the normal conus medullarismay be caudal to the superior endplate of L3.14 In a preterm neonate with a conus that termi-nates at the L3 midvertebral body, a follow-up sonogram after age correction of 40 weeks’ gestation but before age correction of 6 months is warranted.8 The level of termination of theconus and its configuration should be documented, as well as any deviations from normal.

The vertebral level can be determined in a number of ways.15,16 These include:

1. After assessment of the normal lumbosacral curvature to locate the last lumbar vertebraor L5, the vertebral level of the conus is determined by counting the cephalad. Thismethod tends to be more reproducible than the other methods described below, whichrely on counting the number of rib-bearing vertebrae or the number of ossified sacraland coccygeal segments and can lead to less reliable results.

2. The first coccygeal segment has variable ossification at birth but, if ossified, can be distin-guished by its more rounded shape compared with the square or rectangular shape of thesacral bodies. Counting cephalad from S1 again can help determine the vertebral level ofthe conus.


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3. The last rib-bearing vertebra can be presumed to be T12, and the sequential lumbar levelcan be thus determined.

4. When the level of the conus cannot be definitively assessed as normal or abnormal, cor-relation with previous plain radiographs, if available, is helpful. A radiopaque marker canbe placed on the skin at the level of the conus under sonographic guidance, followed byand correlated with a spine radiograph.

The level of termination of the cord is important in assessment of tethering. The cord positionwithin the spinal canal and motion of cord and nerve roots are also helpful guidelines in assess-ment for cord tethering. The normal position of the cord within the spinal canal, and deviationfrom normal, such as apposition to the dorsal aspect of the spinal canal as seen in tethering,should be documented. Cine evaluation can be helpful both in depicting anatomy and in show-ing movement of the distal cord and nerve roots in conjunction with cardiac-related pulsationsof the spinal CSF. M-mode imaging can also be very helpful in documenting motion of thecord and nerve roots. The normal nerve roots pulsate freely with cardiac and respiratorymotion, layer dependently with variable patient positioning, and are not adherent to eachother. Cine evaluation can also document changes that occur with head flexion and extension.A standoff pad or a thick layer of coupling gel may be used, if needed, to follow a tract from theskin surface.

The integrity of the cord should be documented. Areas of abnormal fluid accumulation, suchas hydromyelia or syringomyelia, anterior, lateral, or posterior meningoceles or pseudo-meningoceles, or arachnoid cysts, should be documented and their level identified. Transverseimages are essential to identify and document diastematomyelia, with off-center scanning toavoid the potential pitfall of a reverberation artifact creating a lateral duplication or ghostimage.17,18

The subarachnoid space should be evaluated for a normal anechoic appearance, interrupted bynormal hyperechoic linear nerve roots and dentate ligaments. The subarachnoid space, dura,and epidural space should be evaluated, and abnormalities such as hematoma, lipoma, andother masses should be documented.

In addition to the termination of the conus, the termination of the thecal sac, typically locatedat S2, should be documented. The normal filum measures less than 2 mm in thickness. If thefilum is abnormally hyperechoic or appears thickened, it should be measured and document-ed. The nerve roots of the cauda equina should be delineated within the thecal sac. In cases offailed lumbar puncture, additional imaging with the child supported in a seated position, bend-ing forward, may be useful to allow gravity to distend the lower thecal sac with CSF.

Upright positioning can be used for image guidance of lumbar puncture or to depict meningo-celes or pseudomeningoceles in some patients. Anterior meningoceles or presacral massesshould also be scanned from an anterior position.

The vertebral bodies and posterior elements should be evaluated for deformities. Dysraphicdefects with open posterior elements should be documented on transverse views.


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VI. Documentation

Adequate documentation is essential for high-quality patient care. There should be a perma-nent record of the ultrasound examination and its interpretation. Images of all appropriateareas, both normal and abnormal, should be recorded. Variations from normal size should beaccompanied by measurements. Images should be labeled with the patient identification, facility identification, examination date, and side (right or left) of the anatomic site imaged. An official interpretation (final report) of the ultrasound findings should be included in thepatient’s medical record. Retention of the ultrasound examination should be consistent bothwith clinical needs and with relevant legal and local health care facility requirements.

Reporting should be in accordance with the AIUM Practice Parameter for Documentation of an Ultrasound Examination.

VII. Equipment Specifications

Sonography of the infant spine should be performed with real-time scanners using high-frequency linear array transducers, typically 7 to 10 MHz or higher in neonates.19 When possi-ble, panoramic views of the entire spinal canal are very helpful in providing an overview of theanatomy and termination of the cord and thecal sac. Images of the craniocervical junction mayneed to be obtained with a small vector or tightly curved array transducer.

VIII. Quality Control and Improvement, Safety, InfectionControl, and Patient Education

Policies and procedures related to quality control, patient education, infection control, and safety should be developed and implemented in accordance with the AIUM Standards andGuidelines for the Accreditation of Ultrasound Practices.

Equipment performance monitoring should be in accordance with the AIUM Standards and Guidelines for the Accreditation of Ultrasound Practices.

IX. ALARA Principle

The potential benefits and risks of each examination should be considered. The ALARA (as low as reasonably achievable) principle should be observed when adjusting controls thataffect the acoustic output and by considering transducer dwell times. Further details onALARA may be found in the AIUM publication Medical Ultrasound Safety, Third Edition.


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Acknowledgments

This parameter was revised by the American Institute of Ultrasound in Medicine (AIUM) incollaboration with the American College of Radiology (ACR), the Society for PediatricRadiology (SPR), and the Society of Radiologists in Ultrasound (SRU) according to theprocess described in the AIUM Clinical Standards Committee Manual.

Collaborative CommitteeMembers represent their societies in the initial draft and final revision of this parameter.

Original copyright 2007; Revised 2011Renamed 2015


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AIUMHarris L. Cohen, MD Judy A. Estroff, MDCharlotte Henningsen, MS, RDMS, RVT

ACRMarta Hernanz-Schulman, MD, ChairLori L. Barr, MDLeann E. Linam, MD

SPRDavid A. Bloom, MD

Caroline T. Carrico, MD

Lynn A. Fordham, MD

Martha M. Munden, MD

SRUDorothy I. Bulas, MDBrian D. Coley, MD Harriet J. Paltiel, MD

AIUM Clinical Standards Committee David Paushter, MD, ChairLeslie Scoutt, MD, Vice ChairLisa Allen, BS, RDMS, RDCS, RVTMert Bahtiyar, MDHarris Cohen, MDLin Diacon, MD, RDMS, RPVIJudy Estroff, MDJ. Christian Fox, MD, RDMSCharlotte Henningsen, MS, RT, RDMS,RVTAdam Hiett, MD, RDMSLars Jensen, MDChristopher Moore, MD, RDMS, RDCSSteven Perlmutter, MDOlga Rasmussen, RDMSCarl Reading, MDShia Salem, MDDaniel Skupski, MDJay Smith, MDLami Yeo, MD


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Neonatal -Infant Spine Ultrasound