Investigation of the radiological relationship between iliac crests, conus medullaris and vertebral level in children

Preprocedural Ultrasound for Infant Lumbar Puncture: A Randomized Clinical Trial

BACKGROUND

Our purpose was to determine the potential effect of preprocedural ultrasound (US) to increase lumbar puncture (LP) success compared with standard palpation method. Further, we assessed feasibility of and clinician satisfaction with a standardized US protocol.

METHODS

This prospective, two-arm, parallel-group randomized trial was conducted in a single-center pediatric emergency department. We compared preprocedural US versus palpation method on success with infant LPs. Infants less than 3 months of age requiring LP were enrolled. Sixteen pediatric emergency medicine physicians with varied US experience were trained to conduct the USs to mark interspace locations. Primary outcome was successful LP, defined as obtaining a cerebrospinal fluid (CSF) sample on first attempt with < 1,000 red blood cells per high-powered field (clear CSF). Secondary outcomes included clear CSF on any attempt, any CSF on the first attempt, traumatic LP proportion, and LP attempt frequency. Feasibility was assessed by comparing provider number attempting the LP and procedure duration. Clinician satisfaction and sonographer perceptions of US acceptability and impact were assessed.

RESULTS

Eighty-one patients consented and 80 were analyzed (99%): 40 per group. No statistical difference was seen for the primary outcome (p > 0.05) between intervention and control groups (difference 3%; 95% confidence interval = -19% to 24%). There were no statistical differences between intervention and controls groups for secondary outcomes including the rate of traumatic LPs, number of attempts, and the duration of LP procedure. Most sonographers (84%) strongly agreed or agreed that the US protocol was technically easy to perform, well tolerated by the patient (94%), well accepted by the family (100%), and well accepted by the LP procedural clinicians (99%). In the US group, the majority of clinicians who performed the LPs (68.4%) noted that the preprocedural US influenced their behavior, most commonly helping with overall visualization at the selected interspace (28.9%) or prompting a change in interspace (26.3% higher, 5.3% lower). Seventy-seven percent agreed or strongly agreed that they would like to use the technique again for their next LP. The mean US duration was 4.6 minutes.

CONCLUSIONS

Preprocedural US by did not improve the rates of first-attempt success when compared with palpation method. Our results suggest that US is feasible and well accepted, with a perceptible impact on care.

The Sonographic Appearance of Spinal Fluid at Clinically Selected Interspaces in Sitting Versus Lateral Positions

OBJECTIVE

Our objective was to describe the sonographic appearance of fluid at clinically selected interspinous spaces and see if additional interspaces could be identified as suitable and safe targets for needle insertion. We also measured the reproducibility of fluid measurements and assessed for positional differences.

METHODS

A prospective convenience sample of infants younger than 3 months was enrolled in the pediatric emergency department. Excluded were clinically unstable infants or those with spinal dysraphism. Infants were first held in standard lateral lumbar puncture position. Pediatric emergency medicine (PEM) physicians marked infants' backs at the level they would insert a needle using the landmark palpation technique. A PEM sonologist imaged and measured the spinal fluid in 2 orthogonal planes at this marked level in lateral then sitting positions. Fluid measurements were repeated by a second blinded PEM sonologist.

RESULTS

Forty-six infants were enrolled. Ultrasound verified the presence of fluid at the marked level as determined by the landmark palpation technique in 98% of cases. Ultrasound identified additional suitable spaces 1 space higher (82%) and 2 spaces higher (41%). Intraclass correlation coefficient of all measurements was excellent (>0.85), with differences noted for sitting versus lateral position in mean area of fluid 0.34 mm versus 0.31 mm (difference, 0.03; 95% confidence interval [CI], 0.005-0.068), dorsal fluid pocket 0.23 mm versus 0.15 mm (difference, 0.08; 95% CI, 0.031-0.123), and nerve root-to-canal ratio 0.44 versus 0.51 (difference, 0.07; 95% CI, 0.004-0.117).

CONCLUSIONS

Ultrasound can verify the presence of fluid at interspaces determined by the landmark palpation technique and identify additional suitable spaces at higher levels. There were statistically greater fluid measurements in sitting versus lateral positions. These novel fluid measurements were shown to be reliable.

The influence of age on positions of the conus medullaris, Tuffier's line, dural sac, and sacrococcygeal membrane in infants, children, adolescents, and young adults

BACKGROUND

The purpose of this study was to analyze the distances between the conus medullaris and the Tuffier's line, and between the dural sac and the sacrococcygeal membrane (SCM) in the same pediatric population.

METHODS

Spinal magnetic resonance images and simple X-ray images of 350 patients aged from 1 month to 20 years were reviewed. Positions of the conus medullaris, Tuffier's line, the dural sac, and the SCM were identified. Each position was recorded in relation to the corresponding vertebral body segments. The distances between the conus medullaris and Tuffier's line, and between the dural sac and the SCM, were measured and then assessed according to age using an analysis of variance and a linear regression analysis.

RESULTS

The median levels of the conus medullaris and Tuffier's line were in the lower third of L1 [the first lumbar vertebral body] and the middle third of L5, respectively. The levels of the conus medullaris and Tuffier's line were lower in younger populations. The distance between the conus medullaris and Tuffier's line ranged from 1.5 to 4.75 vertebral body height. However, a narrow range of 1.5-2.5 vertebral height was observed only in children younger than 2 years. The level of the dural sac did not differ greatly by age, but the upper limit of the SCM was lower in older populations. The distance between the dural sac and the upper limit of the SCM increased with age.

CONCLUSIONS

In children, there is a distance of 1.5-4.75 vertebral body height between the conus medullaris and the Tuffier's line. However, these distances were narrower among younger populations. The distance between the dural sac and the upper limit of the SCM increased with age.

Neonatal lumbar puncture: are clinical landmarks accurate?

BACKGROUND

The intercristal line (ICL), defined by the superior aspect of the iliac crest, is used to clinically identify the entry point for lumbar puncture (LP) in neonates. Accepted practice is to insert the needle at the L3/4 or L4/5 intervertebral space.

AIM

To investigate the vertebral level crossed by the ICL as determined by manual palpation and the ability of manual palpation to reliably identify a specified intervertebral space.

METHOD

A total of 30 term neonates were recruited. Paediatricians identified and marked the ICL and the intervertebral space above, with babies in left lateral position. The anatomical positions of both points and the end of the conus medullaris were confirmed using ultrasonography.

RESULTS

The ICL was marked from L2/3 to L5/S1. In 25 babies (83%), the ICL was identified at the desired vertebral level between L3/4 and L4/5. The intervertebral space above this line was marked between L1/2 to L4/5. The potential site for LP was identified higher than intended in 11 cases (36%). The end of the conus medullaris ranged from L1 to L3 terminating at L2 or lower in 11 cases (36%).

CONCLUSIONS

There are wide variations in the positions of the ICL and potential LP site. Using the ICL to guide LP does not appear to be accurate, raising the possibility of potential spinal cord damage.

Lumbar Disk Herniation in Children and Adolescents: The Significance of Configurations of the Lumbar Spine

BACKGROUND

Lumbar disk herniation in adults is thought to be caused by repetitive overloading and age-rated degenerative changes. However, these causes are absent in children and adolescent patients. We assume that structural malformations in the lumbar spine could predispose intervertebral disks to early degeneration and hence need to be surgically fused. This issue has never been raised before.

OBJECTIVE

To investigate the assumption that structural malformations in the lumbar spine could predispose intervertebral disks to early degeneration and hence need to be surgically fused.

METHODS

Lumbar spine configurations, including the height of the intercrestal line, the length of L5 transverse processes, and the presence of transitional vertebrae, were recorded from anteroposterior radiographs taken from 63 consecutive pediatric patients with lumbar disk herniation admitted to our hospital over a period of 8 years. Each configuration was compared in relation to the level of disk herniation. Diskectomy alone was performed in 36 cases; arthrodesis was added in the remaining 27 cases. Patients' back and leg pain visual analog scale scores and frequency and their Oswestry Disability Index scores were recorded before surgery and at follow-up. The results were compared for assessment of outcome.

RESULTS

Patients with high intercrestal lines and long L5 transverse processes had a significantly higher incidence of L4/5 disk herniation, whereas low intercrestal line and lumbarization were associated with L5/S1 disk herniation. Patients' visual analog scale scores, pain frequency, and Oswestry Disability Index score all improved significantly after surgery, but there was no significant difference with or without arthrodesis.

CONCLUSION

Pediatric lumbar disk herniation is significantly associated with structural malformations of the lumbar spine, but arthrodesis does not improve the clinical outcome.

ABBREVIATIONS

ICL, intercrestal lineLDH, lumbar disk herniationL5TP, L5 transverse processODI, Oswestry Disability IndexTV, transitional vertebraeVAS, visual analog scale.

Conus Medullaris Level in Vertebral Columns With Lumbosacral Transitional Vertebra

BACKGROUND

The estimated prevalence of lumbar or sacral transitional vertebrae (LSTV) in the population is 4% to 30%. Few small patient series have studied the normal level of the conus medullaris (CM) in individuals with LSTV.

OBJECTIVE

To determine, by using a large cohort of patients, whether individuals of all ages with LSTV have different CM positions in the spinal canal in comparison with the rest of the population with normal vertebral columns.

METHODS

We performed an institutional retrospective analysis of spinal magnetic resonance images on individuals with LSTV of all ages, sexes, and pathologies during a 10-year period. Fifty-seven percent of patients (n = 467) had a lumbarized vertebra and 43% had sacralized vertebra (n = 355). Mean age at the time of the study was 55 ± 19 years (range 1-97 years). Fifty-two percent were male and 48% were female. Sixty percent of subjects with a sacralized vertebra were female, and 54.5% of those with a lumbarized vertebra were male (P = .001).

RESULTS

The CM in individuals with a lumbarized vertebra was seen to be lower at L1-2 to L2s, than un those with a sacralized vertebra where most conuses were at T12-L1 to L1s (P ≤ 0.001). The CM level was similarly distributed among sexes and ages.

CONCLUSION

In our series, the CM level, when lumbarization occurred, was lower, with a mean level at L1-L2, whereas a more superior mean level at T12-L1 was seen when sacralization occurred. CM level was not influenced by sex, age, or pathology other than tethered cords.

Accuracy of manual palpation vs ultrasound for identifying the L3-L4 intervertebral space level in children

BACKGROUND

Insertion of needles into the spinal or epidural space is an important component of modern anesthetic practice. Needles are usually inserted at or below the L3-L4 intervertebral space to minimize the risk of spinal cord injury. Manual palpation is the most common method for identifying intervertebral spaces. However, anesthesiologists are increasingly using ultrasonography to guide the placement of regional, including neuraxial, anesthetic, and analgesic blocks. We undertook an observational study to compare the accuracy of manual palpation and ultrasound for determining the L3-L4 intervertebral space level.

METHODS

Thirty children 0-12 years of age undergoing lumbar puncture were enrolled. For each subject, an anesthesiologist, using the landmark palpation method, determined the point on a radio-opaque ruler that corresponded to the L3-L4 intervertebral space. A different anesthesiologist using the ultrasound method repeated this measurement. Fluoroscopy was then used to confirm the accuracy of each technique. The proportion of inaccurate measurements and the effects of anesthesiologists' experience, patient age, and size on the accuracy of each technique were compared.

RESULTS

Thirty-seven percent of measurements by the landmark palpation method were inaccurate by ≥1 levels cephalad to the L3-L4 intervertebral space. However, less experienced anesthesiologists (residents and fellows) made a disproportionate number of inaccurate measurements compared to consultants. Twenty-three percent of measurements by the ultrasound method were inaccurate by ≥1 cephalad levels. The BMI-for-age percentile/weight-for-length percentile was higher in patients in whom either technique was inaccurate.

CONCLUSION

This observational study found no difference in the accuracy of landmark palpation, when performed by a consultant anesthesiologist, and ultrasound for determining the L3-L4 intervertebral space in children.

The value of Tuffier's line for neonatal neuraxial procedures

The spine of L4 usually lies on a line drawn between the highest points of the iliac crests (Tuffier's line) in adults. Although its accuracy has been questioned, it is still commonly used to identify the spinous process of the 4th lumbar vertebra before performing lumbar neuraxial procedures. In children, this line is said to cross the midline at the level of L5. A literature search revealed that the description this surface anatomical line is vague in neonates. The aims of this study were to determine the vertebral level of Tuffier's line, as well as its distance from the apex of the sacrococcygeal membrane (ASM), in 39 neonatal cadavers in both a prone and flexed position. It was found that when flexed, Tuffier's line shifted from the level of L4/L5 (prone position) to the upper third of L5. The mean distance from the ASM to Tuffier's line was 23.64mm when prone and 25.47 mm when flexed, constituting a statistically significant increase in the distance (P=0.0061). Therefore, in the absence of advanced imaging modalities, Tuffier's line provides practitioners with a simple method of determining a level caudal to the termination of the spinal cord, at approximately the L4/L5 in a prone neonate and the upper margins of L5 when flexed.

Termination of the normal conus medullaris in children: a whole-spine magnetic resonance imaging study

OBJECT

The mean level of the conus medullaris (CM) has been estimated to lie opposite the L1/2 disc space in several previous studies using ultrasound, CT myelography, and magnetic resonance (MR) imaging, but these studies have been limited in examining only the lumbar spine and including patients being evaluated for back pain and sciatica (creating a selection bias). Moreover, significant variability was found in the termination of the CM, with a small subset of subjects having a CM as low as the mid-body of L4. The authors sought to determine the normal level of the CM and its variability.

METHODS

Children with brain or spinal cord tumors who underwent whole-spine surveillance MR imaging were identified retrospectively. The level of the CM was identified in each subject by counting down from C1. Vertebral anomalies, such as lumbarized S1, sacralized L5, or fewer rib-bearing segments, and the presence of fatty filum were noted.

RESULTS

Findings regarding the level of termination of the CM were tightly grouped; the average was at the lower third of L1 and the mode of the distribution was at the L1/2 disc space, with very little variation. No CM ended below the mid-body of L2. The level of the CM was not significantly different among individuals with lumbarized or sacralized vertebrae or 11 rib-bearing segments.

CONCLUSIONS

The CM terminates most commonly at the L1-2 disc space and in the absence of tethering, the CM virtually never ends below the mid-body of L2. A CM that appears more caudal on neuroimages should be considered tethered.

Comparing the anatomical consistency of the posterior superior iliac spine to the iliac crest as reference landmarks for the lumbopelvic spine: A retrospective radiological study

A palpation reference line coursing between the superior-most aspect of the iliac crests has been reported to cross the L4 spinous process or L4/L5 intervertebral space in approximately 80% of the population. Comparable data have not been defined for the line coursing between the posterior superior iliac spines (PSIS). The purpose of this study was to compare the anatomical consistency of the PSIS to the iliac crest as landmarks used for spinal palpation. One hundred computerized tomographic images were reviewed in a three-dimensional setting. Two horizontal lines were constructed on each image: Line 1 representing the superior-most aspect of the iliac crest and Line 2 representing the inferior margin of the PSIS. The vertical distance between each horizontal line and the inferior edge of its respective spinous process were measured. The PSIS corresponded to the S2 spinous process in 81% of subjects and the iliac crest to the L4 spinous process in 59% of subjects. Distance measures suggest that the PSIS was closer to S2 versus the iliac crest to L4 (t = 6.998; P < 0.01). The PSIS crossed S2 more frequently than the iliac crest crossed L4 (chi(2) = 12.719, P < or = 0.01). The study findings support the relationship between the PSIS, and the spinous process of S2 is more consistent when compared to the iliac crest and the spinous process of L4. The PSIS reference line may be used to find S2 as a reference standard in validity and reliability palpation studies in the lower lumbar spine.