Postural Changes of the Dural Sac in the Lumbar Spines of Asymptomatic Individuals Using Positional Stand-Up Magnetic Resonance Imaging

Hirasawa, Y; Bashir, Waseem; Smith, Francis W.; Magnusson, Marianne; Pope, Malcolm H.; Takahashi, Keisuke

doi:10.1097/01.brs.0000255202.94153.ca

Cited by 78 publications

(53 citation statements)

References 7 publications

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“…Hirasawa et al [33] reported that with a posture change from the supine to standing and sitting flexed positions, lumbar dural sac volume expanded and the dural sac cross-sectional area increases in adults. They cited the reason as an increased pressure of cerebrospinal fluid.…”

Section: Discussionmentioning

confidence: 99%

The effect of flexion on the level of termination of the dural sac in paediatric patients

et al. 2009

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SummaryAlthough the anatomy of the spinal cord and its associated structures have been well defined, the effects of body position relevant to neuraxial blockade have not been elucidated. This study was designed to determine the effect of body position on the end of the dural sac in children. After induction of anaesthesia, ultrasound examination was performed to evaluate the location of the dural sac end in the lateral position with a straight back and knee, and in the lateral position with the knees, legs, and neck flexed. The level of the end of the dural sac was determined in relation to the vertebrae. Our data demonstrate that the dural sac shifts significantly cephalad in the lateral flexed position used for neuraxial blockade (p < 0.001). These results suggest that the safety margin to avoid dural puncture during hiatal or S2-3 approach for caudal block can be increased in younger children. Dural puncture is a serious technical complication during single-shot caudal block, which is the most common regional technique for postoperative analgesia for paediatric subumbilical surgery. The prevalence of dural puncture associated with caudal analgesia is relatively low. It has only been shown in several case reports [1,2] or at a rate of 1.2% in previous large-scale studies [3,4]. In the study of 760 children, Busoni did not find any case of dural puncture and Dalens [5] reported only one dural puncture in his series of 750 paediatric caudals. Sometimes it is difficult to identify the sacral hiatus and the caudal space due to variations of anatomical structures or obesity. In these cases, a trans-sacral approach to caudal block, described by Busoni [6], may be used as an alternative method. Although no dural puncture was reported in several trans-sacral approach studies [6][7][8], the risk of dural puncture is a possibility. It is known that the end of the dural sac is located at the S4 level just after birth, then ascends to the S2 level as the child grows [9].The anatomy of the spinal cord and its associated structures have been well defined [10], largely based on post-mortem or imaging studies in the supine or prone positions. Many factors associated with neuraxial anaesthesia have been studied including the structures at the level of the termination of the spinal cord and dural sac [11], vertebral level and shape of the conus medullaris [12], shape of the epidural space [13][14][15], and distance from the skin to the epidural or subarachnoid spaces [16][17][18][19]. However, the effect of body position relevant to neuraxial blockade has not been well studied [20][21][22][23][24], especially in children.Ultrasonography, which is a well-established method of investigating the spinal canal, spinal cord, and meningeal coverings in infants and children, has the advantage of being real time, non invasive and safe [25][26][27]. It allows detection of congenital malformations such as myelocele, myelomeningocele, spinal lipoma, dorsal dermal sinus, tight filum terminale syndrome, diastematomyelia, hydromyelia and syri...

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Section: Discussionmentioning

confidence: 99%

The effect of flexion on the level of termination of the dural sac in paediatric patients

et al. 2009

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“…The images were part of a dataset that had been acquired for a previous study (13). Approval from a local Research Ethics Committee had been obtained and all subjects had given their informed consent.…”

Section: Subjectsmentioning

confidence: 99%

Characterizing the Shape of the Lumbar Spine Using an Active Shape Model

Meakin¹,

Gregory²,

Smith³

et al. 2008

Spine

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Acknowledgements:We thank Dr Y Hirasawa (MD) and Mrs B MacLennan (research radiographer) for acquiring the MR images.Modelling the lumbar spine shape 2 Structured Abstract Study DesignAnalysis of positional magnetic resonance images of normal volunteers. ObjectivesTo compare the reliability and precision of an active shape model to that of conventional lordosis measurements/ Summary of Background DataCharacterisation of lumbar lordosis commonly relies on measurement of angles; these have been found to have errors of around 10 o . MethodsT2 weighted sagittal images of the lumbar spines of 24 male volunteers in the standing posture were acquired using a positional MR scanner. An active shape model of the vertebral bodies from S1 to L1 was created. Lumbar lordosis was also determined by measuring the angles of the superior end-plates. All measurements were performed twice by one observer and once by a second observer. ResultsThe shape model identified two modes of variation to describe the shape of the lumbar spine (mode 1 described curvature and mode 2 described evenness of curvature). Significant correlations were found between mode 1 and total lordosis (R = 0.97, P < 0.001) and between mode 2 and mean absolute deviation of segmental lordosis (R = 0.80, P < 0.001). Intra-and inter-observer reliability was higher for the shape model (ICCs 0.98 -1.00) than for the Modelling the lumbar spine shape 3 lordosis angle measurements (ICCs 0.68 -0.99). The relative error of the shape model (mode 1 = 4 %; mode 2 = 9 %) was lower than the conventional measurements (total lordosis = 10 %). ConclusionsThe shape of the lumbar spine in the sagittal plane can be comprehensively characterised using a shape model. The results are more reliable and precise than measurements of lordosis calculated from end-plate angles. Key wordsLumbar spine; lordosis; positional MRI; Active Shape Model Mini AbstractAn active shape model was used to characterize the shape of the lumbar spine from positional MRI images of 24 male volunteers in the standing posture. The results of the model were more reliable and precise than the conventional method that uses end-plate angle measurements to characterize the lumbar lordosis.Modelling the lumbar spine shape 4

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“…Lumbar cerebrospinal fluid pressure and dural-sac cross sectional area are smallest in the recumbent versus upright positions. 24,25 The dural bulging that is seen in the sitting position, 26 as compared with the lateral or prone positions, has been observed to decrease the force required to puncture the dura with a 17-gauge Tuohy needle. 27 Hence, the lateral position may decrease the possibility of inadvertent dural puncture.…”

Section: Introductionmentioning

confidence: 96%

Neuraxial techniques for labor analgesia should be placed in the lateral position

Tsen

2008

International Journal of Obstetric Anesthesia

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Postural Changes of the Dural Sac in the Lumbar Spines of Asymptomatic Individuals Using Positional Stand-Up Magnetic Resonance Imaging

Cited by 78 publications

References 7 publications

The effect of flexion on the level of termination of the dural sac in paediatric patients

The effect of flexion on the level of termination of the dural sac in paediatric patients

Characterizing the Shape of the Lumbar Spine Using an Active Shape Model

Neuraxial techniques for labor analgesia should be placed in the lateral position

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