Secondary spread of caudal block as assessed by ultrasonography.

By London Spine
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Secondary spread of caudal block as assessed by ultrasonography.

Br J Anaesth. 2012 Apr;108(4):675-81

Authors: Lundblad M, Eksborg S, Lönnqvist PA

Abstract
BACKGROUND: Redistribution and secondary spread after the initial injection of local anaesthetics (LAs) are important factors that contribute to the final spread of caudal block in children. However, to date, these phenomena have yet not been studied in detail. Thus, the aim of this observational study was to define patterns of secondary spread and redistribution of a caudal block by means of real-time ultrasonography scanning and cutaneous testing.
METHODS: Ultrasound assessment of LA spread within the caudal-epidural space and epidural pressure was followed during 15 min after initial injection (1.5 ml kg(-1), ropivacaine 0.2%) in 16 infants. At 15 min post-injection, cutaneous testing was also performed to assess the cranial dermatomal level of the block (at end-tidal sevoflurane 2.5%).
RESULTS: The median ultrasound-assessed cranial spread was Th10 and Th8 at 0 and 15 min, respectively, and the sensory level at 15 min was Th4. The caudal injection was initially found to compress the terminal part of the dural sac, later followed by a partial re-expansion as epidural pressure was returning towards pre-injection values. An intrasegmental redistribution from the dorsal to the ventral compartment of the epidural space was also observed.
CONCLUSIONS: Two separate patterns of secondary spread of caudal block could be observed, being horizontal intrasegmental redistribution and longitudinal cranial spread. The observed bi-directional movement of cerebrospinal fluid (coined ‘the CSF rebound mechanism’) does explain a major part of the difference between the initial ultrasound-assessed cranial level and the final level determined by cutaneous testing.

PMID: 22315327 [PubMed – indexed for MEDLINE]

Ultrasound assessment of cranial spread during caudal blockade in children: the effect of different volumes of local anaesthetics.

By London Spine
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Ultrasound assessment of cranial spread during caudal blockade in children: the effect of different volumes of local anaesthetics.

Br J Anaesth. 2011 Aug;107(2):229-35

Authors: Brenner L, Marhofer P, Kettner SC, Willschke H, Machata AM, Al-Zoraigi U, Lundblad M, Lönnqvist PA

Abstract
BACKGROUND: Despite the large amount of literature on caudal anaesthesia in children, the issue of volume of local anaesthetics and cranial spread is still not settled. Thus, the aim of the present prospective randomized study was to evaluate the cranial spread of caudally administered local anaesthetics in children by means of real-time ultrasound, with a special focus on the effects of using different volumes of local anaesthetics.
METHODS: Seventy-five children, 1 month to 6 yr, undergoing inguinal hernia repair or more distal surgery were randomized to receive a caudal block with 0.7, 1.0, or 1.3 ml kg(-1) ropivacaine. The cranial spread of the local anaesthetic within the spinal canal was assessed by real-time ultrasound scanning; the absolute cranial segmental level and the cranial level relative to the conus medullaris were determined.
RESULTS: All the blocks were judged to be clinically successful. A significant correlation was found between the injected volume and the cranial level reached by the local anaesthetic both with regards to the absolute cranial segmental level and the cranial level relative to the conus medullaris.
CONCLUSIONS: The main finding of the present study was positive, but numerically small correlation between injected volumes of local anaesthetic and the cranial spread of caudally administered local anaesthetics. Therefore, the prediction of the cranial spread of local anaesthetic, depending on the injected volume of the local anaesthetic, was not possible. EudraCT Number: 2008-007627-40.

PMID: 21642642 [PubMed – indexed for MEDLINE]

An evaluation of contrast medium spread on caudal epidurography with the needle positioned toward the affected side in patients with unilateral lumbosacral radiculopathy.

By London Spine
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An evaluation of contrast medium spread on caudal epidurography with the needle positioned toward the affected side in patients with unilateral lumbosacral radiculopathy.

Skeletal Radiol. 2012 Dec;41(12):1613-8

Authors: Lee JH, Yoon DM, Kwon TD, Yoon KB

Abstract
OBJECTIVE: We used caudal epidurography to compare the spread of contrast medium when the needle was inserted toward the affected side in patients with unilateral radiculopathy undergoing caudal steroid injection.
MATERIALS AND METHODS: We enrolled 24 patients with unilateral radiculopathy. A block needle was positioned toward the affected side in the sacral epidural space. After 5 mL of iodinated contrast medium was injected, a standardized anteroposterior view was imaged. Using Adobe Photoshop software, contrast medium spread was assessed by counting pixels within the areas spread on the affected side and on the opposite side, and the pixel counts of the two sides were compared. Spinal nerve root filling was also assessed.
RESULTS: The pixel count within the area of contrast medium spread on the side with the needle was significantly greater than that of the opposite side (mean [SD] 41,368.6 [13,143.1] vs 15,165.3 (10,698.1), P < 0.001]. However, 13.6% of the study patients had greater spread on the opposite side. The rates of L5 and S1 nerve root filling in the affected side were 18.2% and 36.4% respectively.
CONCLUSIONS: When a needle was intentionally inserted toward the side with radiculopathy, the spread of contrast medium and number of delineated roots tended to be greater on the side with the needle, compared with those on the opposite side. However, the pattern of contrast medium spread in the sacral epidural space varied and some patients even had greater spread on the opposite side.

PMID: 22270453 [PubMed – in process]

Subdural spread of injected local anesthetic in a selective transforaminal cervical nerve root block: a case report.

By London Spine
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Subdural spread of injected local anesthetic in a selective transforaminal cervical nerve root block: a case report.

J Med Case Rep. 2012;6(1):142

Authors: Tofuku K, Koga H, Komiya S

Abstract
INTRODUCTION: Although uncommon, selective cervical nerve root blocks can have serious complications. The most serious complications that have been reported include cerebral infarction, spinal cord infarction, transient quadriplegia and death.
CASE PRESENTATION: A 40-year-old Japanese woman with a history of severe right-sided cervical radicular pain was scheduled to undergo a right-sided C6 selective cervical nerve root block using a transforaminal approach under fluoroscopic guidance. An anterior oblique view of the C5-C6 intervertebral foramen was obtained, and a 23-gauge spinal needle, connected to the normal extension tube with a syringe filled with contrast medium, was introduced into the posterior-caudal aspect of the C5-C6 intervertebral foramen on the right side. In the anteroposterior view, the placement of the needle was considered satisfactory when it was placed no more medial than halfway across the width of the articular pillar. Although the spread of the contrast medium along the C6 nerve root was observed with right-sided C6 radiculography, the subdural flow of the contrast medium was not observed with real-time fluoroscopy. The extension tube used for the radiculography was removed from the spinal needle and a normal extension tube with a syringe filled with lidocaine connected in its place. We performed a negative aspiration test and then injected 1.5 mL of 1.0% lidocaine slowly around the C6 nerve root. Immediately after the injection of the local anesthetic, our patient developed acute flaccid paralysis, complained of breathing difficulties and became unresponsive; her respiratory pattern was uncoordinated. After 20 minutes, she regained consciousness and became alert, and her muscle strength in all four limbs returned to normal without any sensory deficits after receiving emergent cardiorespiratory support.
CONCLUSIONS: We believe that confirming maintenance of the appropriate needle position in the anteroposterior view by injecting local anesthetic is important for preventing central needle movement. Because the potential risk of serious complications cannot be completely eliminated during the use of any established selective cervical nerve root block procedure, preparation for an emergency airway, ventilation and cardiovascular support is indispensable in cases of high spinal cord anesthesia.

PMID: 22657834 [PubMed]