Landmarks of the sacral hiatus for caudal epidural block: an anatomical study

Evaluation of sacral hiatus changes in children using ultrasound

Background and objectives

The intercornual distance in the sacral hiatus has yet to be studied precisely in children. This age-stratified, observational study aimed to clarify the changes in sacral hiatus dimensions and to quantify the correlations between the intercornual distance of the sacral hiatus and age, height, weight, and head circumference by using real-time ultrasonography.

Methods

The patients were stratified into three groups: neonates and infants, toddlers, and schoolchildren. In the operating room, the ultrasonic probe was placed at the sacral cornua to obtain a transverse view of the sacral hiatus, and the intercornual distance was measured three times in millimetres.

Results

The study included a total of 156 patients. The mean ± SD (95%CI) of intercornual distance in neonates and infants (<12 months) was 11.58 ± 1.79 (11.11-12.04) mm, 13.29 ± 1.97 (12.71-13.86) mm in toddlers (13-36 months), and 13.36 ± 2.49 (12.64-14.08) mm in schoolchildren (>36 months).The mean values of neonates and infants were different from those of toddlers and schoolchildren (p < 0.001), but it was similar between toddlers and schoolchildren (p > 0.05, 95 % CI mean difference -1.10 to 0.95).Intercornual distance was correlated with age, height, weight, and head circumference before one year of age (Spearman's R values > 0.7), but there was no correlation thereafter (Spearman's p value > 0.05).

Conclusion

In the first year after birth, the intercornual distance increases rapidly with body growth; after one year of age, the sacral hiatus dimension changes significantly. Ultrasound is superior for assessing the gradually ossified cartilage components in older children.

Combined Ultrasound and Fluoroscopy versus Ultrasound versus Fluoroscopy-Guided Caudal Epidural Steroid Injection for the Treatment of Unilateral Lower Lumbar Radicular Pain: A Retrospective Comparative Study

Background and Objectives: This study aimed to evaluate the mid-term effectiveness and safety of a combined ultrasound (US) and fluoroscopy (FL)-guided approach in comparison to US-guided and FL-guided caudal epidural steroid injections (CESI) for treating unilateral lower lumbar radicular pain. Materials and Methods: A total of 154 patients who underwent CESI between 2018 and 2022 were included. Patients were categorized into three groups based on the guidance method: combined US and FL (n = 51), US-guided (n = 51), and FL-guided (n = 52). The study design was retrospective case-controlled, utilizing patient charts and standardized forms to assess clinical outcomes, adverse events, complications during the procedures. Results: In all groups, Oswestry Disability Index and Verbal Numeric Scale scores improved at 1, 3, and 6 months after the last injection, with no significant differences between groups (p < 0.05). The treatment success rate at all time points was also similar among the groups. Logistic regression analysis showed that injection method, cause, sex, age, number of injections, and pain duration did not independently predict treatment success. Blood was aspirated before injection in 2% (n = 1), 13.5% (n = 7), and 4% (n = 2) of patients in the combined US and FL groups, FL-guided groups, and US-guided groups, respectively. Intravascular contrast spread was detected in one patient in the combined method groups and seven in the FL-guided groups. Conclusions: When comparing pain reduction and functional improvement, there was no significant difference between the three methods. The combined method took less time compared to using FL alone. The combined approach also showed a lower occurrence of intravascular injection compared to using FL alone. Moreover, blood vessels at the injection site can be identified with an ultrasound using the combined method. Given these advantages, it might be advisable to prioritize the combined US- and FL-guided therapy when administering CESI for patients with unilateral lumbar radicular pain.

Study on MEV90 of 0.5% ropivacaine for US-guided caudal epidural block in anorectal surgery

Background

Choosing the appropriate concentration and volume of anesthetics is critical for a successful nerve block. The current study aimed to determine the minimum effective volume (MEV) of 0.5% ropivacaine for US-guided CEB in 90% of patients (MEV90) undergoing anorectal surgery. The aims were to reduce the occurrence of complications associated with a sacral blockade in anorectal surgery, broaden the indications for surgical procedures and treatment, and improve patient satisfaction. This study presents the groundwork for the development of individualized anesthetic programs. We believe that the study would serve as a reference for the use of caudal epidural block (CEB) in lower abdominal surgery for intraoperative and postoperative analgesia.

Methods

This study used a biased coin design (BCD) up-and-down method (UDM). We divided the participants into two groups based on gender, and each group independently performed the biased coin design up-and-down method. We used 0.5% ropivacaine for the first patient in each group; however, the volume was 10 ml for men and 8 ml for women. Therefore, the dose of anesthetics given to each patient was determined by the response of the previous patient. If the block of the previous patient failed, the volume was increased by 2 ml in the following patient. Otherwise, the next subject had an 11% chance of receiving a volume of 2 ml less or an 89% chance of receiving no volume change. We defined a successful block as painless surgery with anal sphincter relaxation 15 min after the drug injection. Enrollment was completed after 45 successful caudal blocks for each group.

Results

Caudal epidural block was successfully performed on 50 men and 49 women. The MEV90 of ropivacaine for CEB was calculated to be 12.88 ml (95% CI: 10.8-14 ml) for men and 10.73 ml (95% CI: 9.67-12 ml) for women. Men had a MEV99 of 13.88 ml (95% CI: 12.97-14 ml), and women had a MEV99 of 11.87 ml (95% CI: 11.72-12 ml).

Conclusion

With operability and general applicability, it is possible to increase the success rate of CEB for anorectal surgery to 99% as well as decrease the incidence of anesthesia-related complications. CEB can meet the needs of patients for rapid postoperative rehabilitation, improve patient satisfaction, and lay a solid foundation for postoperative analgesia.

Evaluation of the Level of Dural Sac Tip in Saudi Population: A Magnetic Resonance Imaging Study

Background For the success of procedures such as caudal block, craniospinal irradiation (CSI), and management of lower back pain and to minimize the risk of dural puncture the exact level of dural sac (DS) termination should be known. Objective The evaluation of DS tip location in the Saudi population and exploring possible significant factors that could be used as predictors in clinical prognosis. Methods A total of 200 patients' lumbar sagittal Weighted T2 Magnetic Resonance Imaging (MRI) study were randomly selected from a single-center hospital in-between 2020 and 2021. The DS tip location was determined by generating a perpendicular line from the longitudinal axis of its termination to the corresponding level. Then naming it after an intervertebral disk or a corresponding vertebrate that is divided into three thirds (upper, middle, and lower). Results In most cases, the level of DS termination is at the middle part of S2 (26.5%), followed by the upper part of S2 (25.1%), and the lower part of S2 (20%). In Saudi nationals, the DS tip was in the middle S2 level at 21.5%, upper S2 level at 19.1%, and lower S2 level at 17%. Factors such as age, sex, cause of referral, and nationality had no statistical significance in relation to DS tip location. Conclusion The DS termination level in the Saudi population ranges from disk between L5-S1 to the lower third of S3. Moreover, nationality, age, and cause of referral were not significant in determining the DS termination level. Therefore, it is still important to individualize patients' treatment by using MRI for each case that requires it.

Is "Trigonum sacrale" a real equilateral triangle? Anatomic consideration of sacral hiatus in adult: A three-dimensional CT study for reliable caudal access

This study is the first attempt to examine anatomical characteristics using three-dimensional computed tomography (3DCT) bone images with some parameters, in order to achieve correct and uncomplicated accesses. In addition, the study addresses a long-standing problem in the field and evaluates whether the trigonum sacrale forms an equilateral triangle or not. A detailed anatomic study of the sacral region was carried out on 91 patient 3DCT images. The CT data, in DICOM format, was read into VINCENT software from Fuji Film, with a slice thickness of 0.5 mm. The average length of sacral hiatus was 28.6 ± 8.4 (range 13.8-45.2 mm). The average width of sacral hiatus at the level of sacral cornua was 10.9 ± 2.7 (range 3.8-16.5 mm). The ratio between the length of the oblique and base line formed by the sacral triangle was 0.81 ± 0.12 (range 0.54-1.00). Using 3DCT images translated by the volume rendering technique, we can remove soft tissue from bones virtually. A slice thickness of 0.5 mm makes it a fine image, and permits meticulous measurement, which is different from previous cadaveric studies. Interestingly, our data showed that the ratio between oblique and base line on sacral triangle was <1.0, average 0.81. Findings demonstrated that the trigonum sacrale is not an equilateral triangle. This is useful information for the identification of the sacral hiatus when the landmark-based technique is employed.

Morphometric Study of Sacral Hiatus in Dry Adult Human Sacra: Its Clinical Relevance in Caudal Epidural Block

Introduction: Correct localization of the sacral hiatus is essential for administering a successful caudal epidural block. The present study was undertaken to find out the anatomical variations of sacral hiatus by a metrical method so that it could help anaesthesiologists in the clinical field.

Materials and methods: The study was performed on 140 (83 male and 57 female) adult human sacra. Various parameters of the sacrum studied were as follows: the shape of the hiatus, length of the sacral hiatus, transverse width at the base and anteroposterior diameter at the level of the apex. For each parameter, the mean value (calculated in mm), standard deviation, range and percentage of bones identified correctly were calculated.

Results: Various shapes of sacral hiatus were observed, including inverted “U” in 73 (52.14%), inverted “V” in 33 (23.57%), irregular in 10 (7.14%), elongated in 10 (7.14%) and dumbbell-shaped in 12 (8.57%). Absent sacral hiatus was observed in two (1.43%) specimens. The mean value for the length of sacral hiatus from the apex to the midpoint of the base was found to be 23.26 mm in males and 22.38 mm in females. However, the parameter was found to be statistically not significant. The mean value for transverse width at the base of hiatus was found to be 14.19 mm in males and 13.54 mm in females. The mean value for the anteroposterior diameter of the sacral canal at the apex was found to be 4.57 mm in males and 4.32 mm in females. Both the above parameters were found to be statistically not significant.

Summary and conclusion: The anatomical knowledge of sacral hiatus and its variations are important in caudal epidural anaesthesia, and it may improve the success rate of caudal epidural anaesthesia.

The Effect of Caudal Anesthesia Block on Perioperative Pain Control and Reduction of the Anesthetic Agent in Pediatric Infraumbilical Surgery: A Prospective Randomized Trial Study

Background

Caudal epidural block (CEB) is a commonly performed neuraxial block to provide effective pain relief and analgesia in pediatric patients undergoing infraumbilical surgery.

Aims

This study aimed to compare the effectiveness of adding CEB to general anesthesia (GA) in terms of intra- and postoperative pain management.

Design

Prospective, randomized case-controlled trial study.

Setting

Operation theater, and postoperative recovery rooms at Salmaniya Medical Complex, Bahrain.

Materials and Methods

A total of 74 patients aged 2 months to 6 years with American Society of Anesthesiologists physical status classification I were recruited over a 6-month period between December 2019 and May 2020. Patients were allocated into two groups (Group A, with CEB) or (Group B, without CEB). Both groups were compared based on hemodynamic stability, pain scores, level of sedation, analgesia need, and parental satisfaction.

Statistical Analysis

Data were analyzed using SPSS program. Categorical and numerical variables of both the groups were compared.

Results

Patients with CEB had better hemodynamic stability during the surgical procedure based on heart rate (P = 0.039). Pain intensity scores were less in patients with CEB than those without (P < 0.001). Fentanyl consumption was lower in Group A compared to Group B at the end of surgery (P = 0.002). They were also ambulated earlier and discharged sooner than those without CEB. Parental satisfaction was 92.1% in Group A compared to 63.9% in Group B (P = 0.012).

Conclusions

Adding CEB to GA for intraoperative and perioperative pain control in pediatric patients undergoing infraumbilical surgery makes it more effective, safe, and with better parental satisfaction.

Caudal epidural steroid injection for chronic low back pain: A prospective analysis of 107 patients

BACKGROUND

Low back pain affects 80% of people worldwide at least once in a lifetime and reduces the quality of life and causes absence from work.

OBJECTIVE

To evaluate the pain and functional status of patients with lumbar disc disease who received blind caudal epidural injections (CEI) for pain relief.

METHODS

The records of 107 patients who had been given CEI between September 2017 and January 2018 were retrospectively analyzed. The inclusion criteria were age > 18 years, > 3-month history of low back pain, and diagnosis of lumbar disc disease by magnetic resonance imaging. The epidural injection solution consisted of 2 mL of betamethasone sodium and 8 mL saline. Follow-up examinations were conducted 3 and 6 months post-injection and the patients were evaluated using a visual analog scale (VAS) and the Oswestry Disability Index (ODI).

RESULTS

The most common disc pathology was at the L4-L5 level. The VAS and ODI scores indicated significantly reduced pain at 3 and 6 months compared with the pre-injection baseline. Two patients experienced total anesthesia and paresis of the lower limbs, but recovered fully after 2 weeks. Blood was aspirated during the injection in two patients, but second-attempt injections were successful in both cases. No other complications were observed.

CONCLUSION

Our results suggest that the blind method is safe for administering CEI to patients with chronic low back pain in the absence of radiological screening and results in significant pain relief with improved functional capacity.

The minimum effective concentration (MEC90) of ropivacaine for ultrasound-guided caudal block in anorectal surgery. A dose finding study

Background

Caudal epidural block (CEB) provides reliable anesthesia for adults undergoing anorectal surgery. Despite the widely utilization, the minimum effective concentration for 90% patients (MEC₉₀) of ropivacaine for CEB remains unknown.

Objective

To estimate MEC of ropivacaine for CEB in anorectal surgery.

Design

A prospective dose-finding study using biased coin design up-and-down sequential method.

Setting

Operating room and postoperative recovery area of Chengdu Shangjin Nanfu Hospital, from October 2019 to January 2020.

Patients

50 males and 51 females scheduled for anorectal surgery.

Interventions

We conducted two independent biased coin design up-and down trials by genders. The concentration of ropivacaine administered to the first patient of male and female were 0.25% with fixed volume of 14ml for male and 12ml for female patients based on our previous study. In case of failure, the concentration was increased by 0.05% in the next subject. Otherwise, the next subject was randomized to a concentration 0.05% less with a probability of 0.11, or the same concentration with a probability of 0.89. Success was defined as complete sensory blockade of perineal area 15 min after the block evidenced by the presence of a lax anal sphincter and pain-free surgery.

Main outcome measures

The MEC of ropivacaine to achieve a successful CEB in 90%(MEC₉₀) of the patients.

Results

The MEC₉₀ of ropivacaine for CEB were estimated to be 0.35% (95% CI 0.29 to 0.4%) for male and 0.353% (95%CI 0.22 to 0.4%) for female. By extrapolation to MEC in 99% of subjects (MEC99) and pooled adjacent violators algorithm (PAVA) adjusted responses, it would be optimal to choose 0.4% ropivacaine with a volume of 14ml for male and 12ml for female.

Conclusions

A concentration of 0.35% ropivacaine with a volume of 14ml provided a successful CEB in 90% of the male patients, while 0.353% ropivacaine with a volume of 12ml provided a successful CEB in 90% of the female patients. A concentration of 0.4% and a volume of 14ml for male and 12 ml for female would be successful in 99% of the patients.

Trial registration

Chictr.org.cn identifier: No. ChiCTR 1900024315.

Neonatal and infantile spinal sonography: A useful investigation often underutilized

Sonography is an ideal, effective, noninvasive tool for evaluation of the spinal cord in neonatal and early infantile age groups owing to lack of ossification of the posterior elements of spine. Understanding normal anatomical appearances is a prerequisite for the interpretation of various pathologies of the spinal canal and its contents. This review elucidates normal appearances of the spinal cord in this age group, in both axial and sagittal planes. Usefulness of Doppler sonography is briefly discussed, and special emphasis is placed on normal anatomical variants that may mimic spinal abnormalities. Sonographic appearances of common intraspinal pathologies, both congenital and acquired, are exhaustively described. Key points regarding sonographic diagnosis of important spinal anomalies are emphasized and explained in detail. To conclude, spinal ultrasound is a reliable and widely available screening tool, albeit the usefulness of which is often underestimated.

Estimation of the relationship between the sacral hiatus and other dorsal sacral parameters using principle component analysis

PURPOSE

Correct localization of the sacral hiatus is essential for administering a successful caudal epidural block. The purpose of this study is to create a statistical model of sacral hiatus from dorsal sacral parameters to improve the location of the hiatus and thus, reduce the failure rate. The aim of this investigation was to examine the relationship of sacral hiatus morphology and dimension with sacral curvature. This study further examines the dorsal sacral parameters that could affect the sacral hiatus dimension.

METHODS

Adult, human, dry sacra and three-dimensionally reconstructed sacra from computed tomography imaging of normal subjects were included in the study and measured using digital Vernier calipers of 0.01 mm accuracy and Geomagic freeform plus software, respectively.

RESULT

The most frequent shape of the sacral hiatus was an inverted V (48%) followed by inverted U shape (32%), an irregular shape (12.3%), an M shape (4.7) and an A shape (2.8%). The data were represented by mean and standard deviation. Sacra with M-shaped hiatus had the lowest hiatal length (14.21 ± 5.44 mm), whereas sacra with an inverted V-shaped hiatus had the highest length (25.41 ± 11.3 mm). The anteroposterior diameter of the sacral hiatus at the base in males and females was found to be 3.46 ± 1.48 mm and 2.79 ± 0.83 mm, respectively (P < 0.001). The distance between the caudal end of the median sacral crest and the apex of the sacral hiatus (7.90 ± 6.74 mm, 4.4 ± 5.86 mm) also revealed sexual dimorphism (P < 0.001).

CONCLUSION

The correlations between most of the dorsal sacral parameters and length of the sacral hiatus are significant. The intercornual distance is also moderately correlated with the distance between right and left lateral sacral crest S1 level. Dorsal sacral parameters predicts variance of the sacral hiatus dimension from 40 to 73% and this could be utilized for statistical model of the sacral hiatus.

Correlation of correct needle placement in caudal epidural space and anatomical structures of sacral canal in paediatric patients: An observational study

Background and Aims:

Caudal epidural block (CEB) is commonly performed using surface landmark-based technique in the paediatric patients, with a good success rate. Failure to perform CEB is usually attributable to anatomic variations. The aim of this study was to perform measurements of the anatomical landmarks that are generally used to perform CEB and find a relation between these measurements and successful needle placement.

Methods:

This was an observational study that included 114 patients, aged up to 15 years. Ultrasonography (USG) scan of the sacrococcygeal region with measurement of cornu height, skin to cornu distance, inter-cornu distance (ICD), vertical and oblique size of hiatus were done. Needle placement for CEB was done using the usual palpatory hiatal approach. Needle position was checked by using ultrasound. Spearman correlation coefficient and multi-variate logistic regression were used for measuring the correlation and predictors of correct needle placement, respectively.

Results:

Correct placement of needle was found in 84% patients. Statistically significant correlation was found between all the anatomical parameters. Regression analysis revealed that only ICD had a statistically significant contribution (OR1.67, 95% CI 1.024–2.7; P = 0.04) in predicting an incorrect needle placement. If ICD was less than 12.5 mm, it predicted a difficult needle placement; all the children were less than 1.5 years in age; AUC was 77%, P = 0.001, sensitivity 83% and specificity 76.5%.

Conclusion:

ICD can be used as predictor of difficult needle placement for CEB. USG guidance may be of help while performing CEB in children less than 1.5 years.

Physiological defects of lumbosacral vertebral arches on computed tomography images in children

OBJECTIVE

Physiological midline defects of the lumbosacral vertebral arches on radiographs must be distinguished from pathological spina bifida. To date, however, this has not been examined, except for some reports based on plain radiography. The aim of this study is to accurately define the rate and distribution of physiological defects by computed tomography (CT) imaging.

METHODS

A total of 115 patients aged 0 months to 16 years (median age, 4 years) who underwent CT scans for abdominopelvic disorder not involving the lumbosacral spine were retrospectively analyzed. The lumbosacral spines were collaterally identified on these images.

RESULTS

In the lumbosacral spine excluding the sacral hiatus, the rate of physiological defects was 66.1% (95% confidence interval [CI]: 56.7-74.7%), and the mean number of defective vertebral arches was 1.6 per patient (95% CI: 1.3-1.9). The rate and mean number of defects were significantly higher in the group of patients less than 6 years old (84.3%, 2.2/patient) than that of patients 6 years old or older (37.8%, 0.5/patient) (p < 0.001 and p < 0.001, respectively). The defect rates by spinal level were S3 (57.4%), S1 (47.8%), S2 (34.8%), L5 (13.0%), L4 (2.6%), and L3 (0.9%) in descending order.

CONCLUSIONS

Physiological defects were found more commonly at an earlier age and predominantly existed adjacent to the sacral hiatus (S3) and around S1. Understanding the detection rate and distribution features of defects more precisely on CT images will contribute clinically supportive information to distinguish between physiological defects and pathological spina bifida.

Assessment of Morphological and Morphometrical Variations of Sacral Hiatus in Dry Human Sacrum in Ethiopia

Background

The sacral hiatus is an opening present at the lower end of the sacral canal. The anatomy of the sacral hiatus and its variations are clinically important during administration of caudal epidural block (CEB) in obstetrics and gynecology, orthopedic, urology and general surgical practices. The success and reliability of CEB depends upon the sound knowledge of anatomical variations of the sacral hiatus.

Objective

The aim of this study was to assess the morphological and morphometric variation of the sacral hiatus in dry human sacrum.

Methods

An institution-based observational cross-sectional study design was conducted to assess morphological and morphometric variations of the sacral hiatus in 61 dry human sacrum specimens at the anatomy departments of Gondar, Addis Ababa, Hawassa and Jimma universities and Hayat and Korea Medical Colleges in Addis Ababa. Descriptive analysis was applied to analyze the data.

Results

The most commonly recorded shape of the sacral hiatus is inverted-V (41%) followed by inverted-U (37.7%). The least common was complete bifida (1.6%). The apex of the sacral hiatus is mostly seen at the level of the 4th sacral vertebra (60.7%), while the base is commonly located at the level of the 5th sacral vertebra (78.7%). The mean length of the sacral hiatus is 22.67 ± 11.84 mm. The mean transverse width and mean anteroposterior diameter of the sacral hiatus at the apex are 13.14 mm ± 2.85 mm and 5.57 mm ± 1.53 mm, respectively.

Conclusion

The sacral hiatus has anatomical variations. These variations should be kept in mind during administration of caudal epidural anesthesia and analgesia.

A Morphometric and Radiological Study of Sacral Hiatus in Human Adult Sacra and Its Clinical Relevance in Caudal Epidural Anaesthesia

Background: The knowledge of sacral hiatus anatomy is crucial in clinical situations requiring caudal epidural block for various diagnostic and therapeutic procedures of the lumbosacral spine to avoid complications and failure rate. This study was undertaken to compare morphometric characteristics of sacral hiatus in human dry sacra and pelvic radiographs for placing the needle more accurately in the sacral hiatus landmarks to permit correct, painless, and uncomplicated caudal epidural accesses. Materials and methods: The present study was done on 138 human adult dry sacra and 110 anteroposterior lumbosacral spine radiographs of the North Karnataka region of India. Sacral hiatus was evaluated in each sacrum based on its shape, level of its apex, and base according to sacral and coccygeal vertebrae, length, anteroposterior diameter at its apex, and transverse width at its base. Results:The mean length of sacral hiatus in men and women was 27.81+1.17 mm and 24.73+2.21 mm, respectively. The mean anteroposterior diameter of the sacral hiatus at the apex was 6.24+2.73 mm in males and 6.63+2.81 mm in females. The transverse width of the sacral hiatus at the base was 17.56+1.81 mm in males and 17.92+2.59 mm in females. The location of the apex of sacral hiatus was the highest in number at the level of the fourth sacral vertebra (23.63%). The location of apex in radiographs of all lumbosacral spine S3 showed 49.09% maximum. The location of the base of the sacral hiatus was observed in the dry sacra at the level of the fifth sacral vertebra (64.54%). In the present study, different shapes of the sacral hiatus were recorded. The most common shape in males and females was inverted U shape (42.02%), followed by inverted V shape (26.08%) and dumbbell shape (12.31%). The least common shape was observed in the bifid sacra (5.07%). In 2.17% of cases, sacral hiatus was absent. Percentage of absence, agenesis, irregular, and bifid shapes were found rather in female than male sacra. An anteroposterior view of spine radiograph showed sacral hiatus agenesis in both females (7.81%) and males (4.34%). The anatomical knowledge of sacral hiatus and its variations are important in caudal epidural anesthesia, and it may improve the success rate of caudal epidural anesthesia.

Anatomical study of the human sacral hiatus and implications for successful caudal epidural injection

BACKGROUND

Caudal epidural injection (CEI) is a commonly used procedure to treat back and leg pain secondary to nerve root irritation, predominantly in the context of spinal canal stenosis. Key to a successful outcome is correct needle placement. Although fluoroscopic guidance confirms accurate needle placement, it does not help in determining the starting point, which can lead to multiple needle insertions.

OBJECTIVE

This study aimed to determine the variability in size and position of the sacral hiatus and to identify reproducible surface landmarks to locate its position.

METHODS AND STUDY DESIGN

250 human sacral bones were examined, measuring morphology and structure. Vernier callipers accurate to 0.1 mm were used for measurements. Results were analysed using SPSS statistical software.

RESULTS

Two specimens were excluded due to agenesis of the hiatus (0.8%). Of the remaining 248 specimens, it was found that the mean internal diameter of the sacral hiatus was 5.12 mm (SD 1.61). The position of the hiatus was variable but was most commonly found at the level of the fourth sacral vertebrae (62.9%, n = 156). Mean distance between the two superolateral sacral prominences was 64.15 mm (SD 6.5) and between superolateral sacral prominences (left and right) and apex of the hiatus were 63.21 mm (SD 10.9) and 63.34 mm (SD 10.87) respectively.

CONCLUSION

Although there is a clear anatomical variance in the position and size of the sacral hiatus, this study suggests that surface anatomy landmarks can be used to form an equilateral triangle of which the inferior apex should correspond to the sacral hiatus. Knowledge of this surface anatomy may assist the correct location of the sacral hiatus and hence subsequently improve the efficacy of CEI.

Risk of rectal puncture due to needle entry into the presacral space: Importance of measuring the distance between the rectum and sacrococcyx, and the thickness of the sacrococcyx

During ganglion impar block, the needle may approach the presacral space and the sacrum may be penetrated during caudal anesthesia. Because the rectum is in front of the sacrococcyx and is thus at risk for puncture, it is important to determine the distance between the sacrococcyx and rectum, as well as the thickness of the sacrococcyx.Computed tomography was used to measure the distance between the rectum and sacrococcyx, as well as the thickness of the sacrococcyx. The distances between the coccyx and rectum, sacrococcygeal joint and rectum, sacral level 5 ('sacrum 5') and rectum, and 'sacrum 4 to 5 junction' and rectum were measured. The results were compared based on the presence or absence of stools in the rectum. The thickness of the sacrococcyx was measured at the sacrum 4 to 5 junction and sacrococcygeal joint.In total, 1264 patients were included in this study. All distances were less than 1 mm in both males and females, with the exception of the distance between the coccyx and rectum in males. In both males and females, there was no significant difference in distance between the sacrococcyx and rectum according to the presence or absence of feces in the rectum, but there was a difference in the distance between sacrum 5 and the rectum in males (P = .048). Several male and female patients showed thicknesses of less than 5 mm at the sacrococcygeal joint.Some patients have a distance of less than 1 mm between the sacrum and rectum. Practitioners should exercise caution when applying a needle to the presacral space. If the sacrum is accidentally penetrated during caudal block, rectum puncture cannot be ruled out. Excretion of feces does not influence the distance between the sacrococcyx and rectum in females.

Imaging anatomy of the vertebral canal for trans-sacral hiatus puncture of the lumbar cistern

A standard lumbar puncture may be impossible for many anatomic or technical reasons. Previous accounts of caudal epidural anesthesia and other procedures via the sacral hiatus prompted us to test if image-guided percutaneous trans-sacral hiatus access to the lumbosacral subarachnoid cistern would be anatomically feasible. To study vertebral canal morphometry and curvature, we analyzed midsagittal computed tomography-myelogram images of 40 normal subjects and digitally measured sacral curvatures between S1 to S5 and S2 to S4 using two methods whereby a lower angle signifies a straighter sacrum. We measured midsagittal vertebral canal area, hiatus width, dural sac termination levels, and distance from sacral hiatus to the dural sac tip (needle distance). Subjects were F:M = 25:15, with a mean age of 44.9 years. The two S1-S5 full sacral curvature mean angles were 57.3° and 60.4°. Almost all sacral hiatuses were at S4, and dural sac terminations were at S1-S2. The mean S2-S4 sacral curvature was 25.1°, and the mean needle distance was 57.7 mm. Using two-way analysis of variance, there were significant sex differences for needle distances (p = .001), and full and limited sacral curvatures (p = .02, and p = .046, respectively). There were no significant linear regression correlations between age and sacral curvature, needle distance, canal area, or hiatus width. Therefore, despite a frequently prominent full sacral curvature, the combination of S1-S2 dural sac termination plus a relatively straight trajectory of the lower vertebral canal between S2 and S4 support the theoretical feasibility of percutaneous trans-sacral hiatus and vertebral canal access to the lumbosacral cistern using a standard spinal needle.

Sacral anatomical interspace landmark for lumbar puncture in pregnancy: A randomized trial

OBJECTIVE

To determine whether the sacral anatomical interspace landmark (SAIL) technique is more accurate than the classic intercristal line (ICL) technique in pregnant patients and to assess the percentage of clinical determinations above the third lumbar vertebra.

METHODS

In this prospective, randomized, open-label trial, there were 110 singleton pregnant patients with gestational age greater than 37 weeks included. Selection procedure was a convenience sample of pregnant patients who presented for office visits or vaginal or cesarean delivery between March 15 and July 31, 2018, at a single-center obstetric tertiary care university hospital. Both techniques were evaluated by 2 physicians independently assessing each method. Before data collection, we hypothesized that the SAIL technique would be more accurate than the ICL technique in determining the L4-L5 interspace, and that the SAIL technique would produce more estimations below the third lumbar vertebra than the ICL technique. Therefore, the primary outcome was accuracy in identifying the L4-L5 lumbar interspace with SAIL vs ICL. The secondary outcome was difference in clinical assessments above the third lumbar vertebra. Both outcomes were measured via ultrasonography.

RESULTS

Patients were 31 ± 5 years of age (mean ± SD) and had body mass index of 31.8 ± 5.7 kg/m² and gestational age of 38.8 ± 1.1 weeks. A total of 110 patients were analyzed. SAIL correctly identified the L4-L5 interspace 49% of the time vs 8% using ICL (p < 0.0001). Estimations above L3 were 1% for SAIL vs 31% for ICL (p < 0.0001).

CONCLUSIONS

Our study shows improved accuracy in identifying intervertebral space using the SAIL technique; this may prevent direct mechanical trauma to the conus medullaris when lumbar punctures are performed in pregnancy.

CLINICALTRIALSGOV IDENTIFIER

NCT03433612.

Surgically assisted caudal anesthesia in a case of Ankylosing Spondylitis-An innovative approach

Anticipated difficult endotracheal intubation and impossibility of conventional methods of neuraxial blocks in Ankylosing Spondylitis (AS) led to our search for an alternative technique of regional anesthesia for total hip replacement surgery in such a patient. The approach undertaken was, after infiltration of the area with a local anesthetic drug, an orthopedic surgeon drilled the posterior wall of sacral hiatus and surgically created a small opening on it. A nerve stimulator needle was then introduced through this opening to get muscle twitches of the great toe, which helped in identification of the sacral epidural space. 30 ml of 0.5% injection ropivacaine was then deposited in this extradural space. Motor and sensory blocks developed within 10 minutes. The novel approach of surgically assisted drilling of the posterior wall of sacral hiatus may be established as an alternative approach to the classical caudal anesthesia when other alternatives fail.

Anatomical Evaluation of the Sacral Hiatus Using Ultrasound Imaging: Factors That Inhibit Needle Insertion During Caudal Epidural Block Procedures

OBJECTIVE

Caudal epidural blocks often fail due to the difficulty of appropriate needle insertion. This study aimed to evaluate the anatomy of the sacral hiatus using ultrasound imaging.

METHODS

This was a retrospective study involving 76 patients with spinal disorders. The following factors were analyzed to see if they affected the palpability of the sacral hiatus: sex, body mass index (BMI), and the morphology of the sacral hiatus on ultrasound imaging. The difficulty of needle insertion and the factors that influenced it were investigated in 28 of the 76 patients, who underwent landmark-based caudal epidural block procedures performed by the same doctor.

RESULTS

Among the 76 patients, the mean length of the sacral hiatus was 21.3 ± 5.6 mm, the mean distance from the skin to the sacral cornua was 5.2 ± 3.4 mm, and the mean angle of the sacral hiatus was 16.4 ± 5.5 degrees. Sacral base protrusion was present and absent in 35 and 41 cases, respectively. The sacral hiatus exhibited good and poor palpability in 53 and 23 cases, respectively. The mean distance from the skin to the sacral cornua and BMI were found to significantly influence the palpability of the sacral hiatus. Only sacral base protrusion significantly influenced the difficulty of needle insertion.

CONCLUSION

The mean distance from the skin to the sacral cornua and BMI were found to be associated with the palpability of the sacral hiatus, and sacral base protrusion was demonstrated to be associated with the difficulty of needle insertion into the sacral hiatus.

Alternative way to find sacral hiatus for blind caudal block - Based on 3D pelvis CT anthropometry: A retrospective study

The aim of this study is to develop an alternative way to locate the sacral hiatus for blind caudal block from the anthropometrical data measured on 3D pelvic CT. The intersection of the line connecting two sacral cornua and the midline is considered the ideal point (IP) for caudal block. The mean length from the coccyx tip to the IP was measured using 3D pelvic CT images in 30 men and 30 women and was 6.5 cm and 6.0 cm, respectively. For the conventional method group, we used the conventional equilateral triangle method to find the sacral hiatus, which was named conventional method group needling point (CNP). For the experimental method group, the point 6.5 cm or 6.0 cm (mean length from the coccyx tip to the IP) away from the coccyx tip was called the experimental method group needling point (ENP). Drawing the three points of the IP, CNP, and ENP on the same patient's 3D pelvic CT, we compared the distance from the IP to the CNP with the distance from the IP to the ENP. We propose that the experimental method is comparable to the conventional method in locating the sacral hiatus, which is crucial for a successful caudal block procedure. Anthropometric measurements and virtual comparative test between two methods were done on the 3D pelvis CT. In men, the distance from the CNP to the IP was 0.8 ± 0.5 cm in the conventional method group, while the distance from the ENP to the IP was 0.5 ± 0.4 cm in the experimental method group (p < 0.05). In women, the same distances were 1.5 ± 0.8 cm and 0.7 ± 0.3 cm, respectively (p < 0.05). In conclusion, finding a point of 6.5 cm from the coccyx tip in men and 6.0 cm in women could be an alternative way to find the sacral hiatus for blind caudal block.

Anatomy of the sacral hiatus and its clinical relevance in caudal epidural block

PURPOSE

Caudal epidural anesthesia (CEB) is widely used for the prevention of chronic lower back pain, the control of intraoperative analgesia such as genitourinary surgery and labor pain cases in sacral epidural space approach for the implementation of analgesia. CEB is an anesthetic solution used into the sacral canal via sacral hiatus (SH). For optimal access into the sacral epidural space, detailed anatomical landmarks of SH are required. This study aims at exploring the anatomical structures and differences of the SH by using the sacral bone as a guide point to failure criteria for reviewing the caudal epidural anesthesia and improving the criteria for success in practice.

MATERIALS AND METHODS

Detailed morphometric measurements of orientation points of the SH were taken in 87 sacral bones. The measurements were taken using digital calipers and calculated with photogrammetric methods using Image J program.

RESULTS

Most commonly encountered shape of the SH was inverted U (33.33%), while 6.9% 3.45% often lack SH and bifida shape were found. The average length of the SH was 28.7 ± 7.1 mm, the average distance of the intercornual distance was 13.48 ± 2.69 mm, the average of the apex of SH and S2 sacral foramen was 34.68 ± 7.09 mm. There was no statistically significant difference determined in bilateral measurements (p > 0.05). Apex and base of SH were most commonly observed against S4 and S5 vertebrae, respectively. The level of maximum curvature of sacrum was S3 in 62.07% and S4 in 28.78%. Findings of spina bifida level were found 16.13% often in L5-S1 segment. Sacral cornua were marked by their bilateral presence in 55.26% and impalpable in 21.05% cases. Minimum distance between the S2 and the apex of the SH was 7.25 mm which suggested that it would not be safe to push the needle beyond 7 mm into the sacral canal so as to avoid dural puncture. In 8.77% cases, the depth of hiatus was less than 3 mm.

CONCLUSIONS

Single bony landmark may not help in locating the SH because of the anatomical variations. Important anatomical landmarks of the CEB are the sacral cornu, lateral sacral crests, the apex of the SH, the base of the SH, the top portion of the median sacral crest, anteroposterior distance of the sacral canal, intercornual distance, distance of the apex of the SH to the S2 foramina. Depth of hiatus less than 3 mm may be one of the causes for the failure of needle insertion. Surrounding bony irregularities, different shapes of hiatus and defects in dorsal wall of sacral canal should be taken into consideration before undertaking CEB so as to avoid its failure. This guide can be done by considering the points and securing a successful venture.

Caudal Epidural Block: An Updated Review of Anatomy and Techniques

Caudal epidural block is a commonly used technique for surgical anesthesia in children and chronic pain management in adults. It is performed by inserting a needle through the sacral hiatus to gain entrance into the sacral epidural space. Using conventional blind technique, the failure rate of caudal epidural block in adults is high even in experienced hands. This high failure rate could be attributed to anatomic variations that make locating sacral hiatus difficult. With the advent of fluoroscopy and ultrasound in guiding needle placement, the success rate of caudal epidural block has been markedly improved. Although fluoroscopy is still considered the gold standard when performing caudal epidural injection, ultrasonography has been demonstrated to be highly effective in accurately guiding the needle entering the caudal epidural space and produce comparative treatment outcome as fluoroscopy. Except intravascular and intrathecal injection, ultrasonography could be as effective as fluoroscopy in preventing complications during caudal epidural injection. The relevant anatomy and techniques in performing the caudal epidural block will be briefly reviewed in this article.

Fluoroscopically Guided Epidural Injections of the Cervical and Lumbar Spine

Advances in imaging and the development of injection techniques have enabled spinal intervention to become an important tool in managing chronic spinal pain. Epidural steroid injection (ESI) is one of the most widely used spinal interventions; it directly delivers drugs into the epidural space to relieve pain originating from degenerative spine disorders-central canal stenoses and neural foraminal stenoses-or disk herniations. Knowledge of the normal anatomy of the epidural space is essential to perform an effective and safe ESI and to recognize possible complications. Although computed tomographic (CT) or combined CT-fluoroscopic guidance has been increasingly used in ESI, conventional fluoroscopic guidance is generally performed. In ESI, drugs are delivered into the epidural space by interlaminar or transforaminal routes in the cervical spine or by interlaminar, transforaminal, or caudal routes in the lumbar spine. Epidurography is usually performed before drug delivery to verify the proper position of the needle in the epidural space. A small amount of contrast agent is injected with fluoroscopic guidance. Familiarity with the findings on a typical "true" epidurogram (demonstrating correct needle placement in the epidural space) permits proper performance of ESI. Findings on "false" epidurograms (demonstrating incorrect needle placement) include muscular staining and evidence of intravascular injection, inadvertent facet joint injection, dural puncture, subdural injection, and intraneural or intradiscal injection. ^©RSNA, 2016 An earlier incorrect version of this article appeared online. This article was corrected on December 22, 2016.

Comparative effectiveness of percutaneous epidural adhesiolysis for different sacrum types in patients with chronic pain due to lumbar disc herniation: A propensity score matching analysis

For percutaneous epidural adhesiolysis (PEA) in patients with chronic low back and/or leg pain, comparative efficacy of lumbar PEA between the sacral types has not yet been investigated. This study aimed to determine the comparative efficacy of lumbar PEA between the sacral types in chronic pain with lumbosacral herniated intervertebral disc (L-HIVD).A total of 1158 chronic low back and/or leg pain patients who diagnosed with L-HIVD and underwent PEA between February 2011 and March 2015 were retrospectively examined. All enrolled patients were divided into 2 types: dome-sacral type and flat type. To avoid confounding bias, propensity score analysis was used. Numeric rating scales (NRS) and Patients' Global Impression of Change (PGIC) were compared between the 2 types at baseline and at 3 months post-PEA.After conducting a propensity score matching analysis, 114 patients were included in each type. The mean sacral angle significantly differed between the flat-sacral and dome-sacral types (P < 0.001). A linear mixed effect model analysis showed that the adjusted NRS score at baseline was 7.58 [95% confidence interval (CI): 7.40-7.76] for the flat-sacral type and 7.47 (95% CI: 7.29-7.64) for the dome-sacral type. The adjusted NRS score after 3 months post-PEA was 4.27 (95% CI: 3.77-4.77) for the flat-sacral type and 3.71 (95% CI: 3.21-4.21) for the dome-sacral type. We detected no significant differences in NRS at baseline (P = 0.371) and after 3 months (P = 0.121) between the 2 groups. No significant differences were observed in terms of the NRS score between the 2 groups during the 3 months follow-up (omnibus P = 0.223). There were no significant differences in PGIC between flat-sacral and dome-sacral types at 3 months after the follow-up period (4.40 ± 2.17 and 4.67 ± 1.88, respectively, P = 0.431).PEA provides sufficient pain relief for chronic pain due to L-HIVD at 3 months postprocedure. The sacral type might not affect the outcome of lumbar PEA in chronic pain associated lumbar HIVD.

Ultrasonographic Evaluation of Anatomic Variations in the Sacral Hiatus: Implications for Caudal Epidural Injections

STUDY DESIGN

Prospective study OBJECTIVE.: The aim of this study was to evaluate variations in the sacral hiatus based on ultrasonographic images.

SUMMARY OF BACKGROUND DATA

Caudal epidural injection is commonly used for the treatment of lower back pain, but blind injections commonly lead to mistakes made at the injection site due to anatomic variations in the sacral hiatus.

METHODS

A total of 339 patients with low back pain or sciatica were studied using a linear-array ultrasound transducer. The transducer was placed at the sacral cornua and the distance between the bilateral cornua and the width of the sacrococcygeal ligament between the bilateral cornua were measured in the transverse view. The transducer was also placed between the two cornua and the distance between the skin and posterior sacral bony surface was measured, including the depth of the subcutaneous fat, in the longitudinal view. The surface distance was then measured from the natal cleft to the apex of the sacral hiatus.

RESULTS

The mean distance between the bilateral cornua was 18.1 ± 3.2 mm and mean width of the sacrococcygeal ligament was 10.5 ± 2.6 mm. The mean diameter of the sacral canal was 6.8 ± 2.5 mm but 6 of 339 patients (1.8%) found less than 2 mm. The mean surface distance from the natal cleft to the apex of the sacral hiatus was 29.3 ± 12.3 mm. The distance between the sacral hiatus and the natal cleft ranged from -2.0 to 75.0 mm.

CONCLUSION

We believe that the variations found in the surface distance from the natal cleft to the sacral hiatus are significant for caudal epidural injection. However, the other measurements may also have clinical importance in this area.

LEVEL OF EVIDENCE

3.

Ultrasound-Guided Versus Fluoroscopy-Guided Caudal Epidural Steroid Injection for the Treatment of Unilateral Lower Lumbar Radicular Pain: Case-Controlled, Retrospective, Comparative Study

The aim of the article is to investigate the efficacy of ultrasound (US)-guided Caudal Epidural Steroid Injection (CESI) compared with fluoroscopy (FL)-guided CESI in patients with unilateral lower lumbar radicular pain. This case-controlled, retrospective, comparative study was done at the university hospital. A total of 110 patients treated with US- or FL-guided CESI were administered a mixture of 20 cc (0.5% lidocaine 18.0  mL + dexamethason 10  mg 2  mL). Outcome measurement was assessed by Oswestry Disability Index (ODI), verbal numeric pain scale (VNS) before injections and at 3, 6, and 12 months after the last injections. Successful outcome was defined as measured by >50% improvement in the VNS score and >40% improvement in the ODI. ODI and VNS showed improvement at 3, 6, and 12 months after the last injection in both groups. No statistical differences in ODI, VNS were observed between groups (P < 0.05). No significant differences in the proportion of patients with successful treatment were observed between the groups from the 3-month to 6-month to 12-month outcomes. US-guided CESI is deserving of consideration in conservative management of unilateral lower lumbar radicular pain.

Anatomic Differences in the Sacral Hiatus During Caudal Epidural Injection Using Ultrasound Guidance

OBJECTIVES

The aim of this study was to clarify differences in the anatomic structure of the sacral hiatus and angle of needle insertion during caudal epidural steroid injection using ultrasound guidance in patients according to sex and age.

METHODS

A total of 237 patients with low back pain with or without sciatica were included. Sonograms of the sacral hiatus were obtained, and caudal epidural steroid injection using ultrasound guidance was performed in all patients. The intercornual distance, diameter of the sacral canal, thickness of the sacrococcygeal ligament, optimal angle for needle insertion, and actual angle of needle insertion were measured.

RESULTS

Between men and women, significant differences were observed for the intercornual distance (17.7 versus 16.5 mm; P< .01) and thickness of the sacrococcygeal ligament (4.3 versus 3.9 mm; P = .02). In all patients, the thickness of the sacrococcygeal ligament (r= 0.28) and diameter of the sacral canal (r= 0.40) were positively correlated with the optimal angle for needle insertion (P < .01). In women, the thickness of the sacrococcygeal ligament (r = -0.24), diameter of the sacral canal (r = -0.27), optimal angle for needle insertion (r = -0.29), and actual angle of needle insertion (r = -0.18) were negatively correlated with age. In men, only the diameter of the sacral canal was negatively correlated with age (r = -0.30).

CONCLUSIONS

We found that the sacral hiatus has anatomic differences between patients of different sexes and ages. Understanding these differences, especially in women, may improve the safety and reliability of caudal epidural steroid injection.

Ultrasound versus anatomical landmarks for caudal epidural anesthesia in pediatric patients

Background

Caudal block is easily performed because the landmarks are superficial. However, the sacral hiatus is small and shallow in pediatric patients. In the present study, we evaluated under general anesthesia whether the distance between the bilateral superolateral sacral crests increased with growth, whether an equilateral triangle was formed between the apex of the sacral hiatus and the bilateral superolateral sacral crests, and whether expansion of the epidural space could be confirmed by ultrasound.

Methods

This prospective observational study included 282 children who were ASA I–II. Under general anesthesia, each patient was placed in the lateral bent knees position, and the attending anesthesiologist drew an equilateral triangle and measured the distance between the bilateral superolateral sacral crests along a line forming the base of the triangle. Then the sacral hiatus was identified by ultrasound. Differences of the distance between the anatomical landmarks measured by the anesthetist and by ultrasound were evaluated.

Results

Two patients were excluded because the superolateral sacral crests and sacral hiatus could not be palpated. The base of the triangle increased in proportion to age up to 10 years old, with a significant correlation between age and the length of the base (Spearman’s r value = 0.97). The triangle was not an equilateral triangle under 7 years old. The sacral hiatus could be identified by ultrasound and we could confirm expansion of the epidural space in all patients.

Conclusion

We observed a correlation between age and the length of the triangle base in children under 10 years old. Although detection of the anatomical landmarks by palpation differed from identification by ultrasound in pediatric patients, performing ultrasound is important. Epinephrine should be added to the anesthetic to avoid complications.

Trial registration

Current Controlled Trials UMIN000017898. Registered 14 June 2015. Date of protocol fixation was 1^st December, 2008 and Anticipated trial start date was 5^th January, 2009.

The influence of injecting an epidural contrast agent into the sacral canal on the fluoroscopic visibility of bony landmarks for sacroiliac screw fixation: a feasibility study

OBJECT

In sacroiliac screw fixation of unstable pelvic injuries in geriatric patients, poor bone quality often obscures important bony landmarks in fluoroscopic images. The authors analyzed the feasibility of injecting a transhiatal contrast agent (CA) into the sacral canal to improve fluoroscopic visualization in the sacral epidural space.

METHODS

Eight fresh cadaveric whole-body specimens from human donors whose mean age at the time of death was 78 years (range 69-87 years) were used. First, to identify bony landmarks without CA enhancement, the authors acquired fluoroscopy images of the native sacral canal, using lateral, inlet, and outlet projections. Through puncture of the sacral hiatus, 8-10 ml of CA was injected into the epidural space. Fluoroscopy images were then acquired in the standard pelvic views to identify the bony landmarks. To assess the effect of the CA enhancement, visibility of the landmarks was assessed before and after CA injection. Each identified landmark was scored as 1, and summative landmark scores of up to 10 were determined for each specimen.

RESULTS

The cadaveric specimens were representative of bone structures in the geriatric population. In all specimens, epidural CA injection enhanced the fluoroscopic visualization of the sacral canal and of the S-1 foramina. The enhancement increased the total bony landmark score from 5.9 (range 4-8) without CA injection to 8.1 (range 6-10) after CA injection. Considering only intrasacral landmarks, the score was increased from 1.5 to 3.

CONCLUSIONS

Injection of a transhiatal epidural CA improves fluoroscopic imaging of the sacral canal and of the neural foramina. Hence, this technique could be applied to help the surgeon identify anatomical landmarks during sacroiliac screw fixation in geriatric patients.

Caudal blockade for children undergoing infra-abdominal surgery

The assessment and management of pain in children can be complicated by their inability to communicate effectively; therefore, it is important that every attempt be made to circumvent the undertreatment of pain. Caudal blockade is associated with excellent pain relief and minimal side effects, and it is an established technique used in conjunction with general anesthesia for children undergoing infra-abdominal surgery. Available local anesthetic agents have a relatively short analgesic duration period, so anesthesia professionals often combine their use with adjuvant medications (eg, epinephrine, clonidine, fentanyl, morphine, preservative-free ketamine, neostigmine). Additional consideration should be given to intraoperative care, postoperative observation (eg, measuring sedation, motor blockade, postoperative nausea and vomiting, pain), and discharge instructions for the patient's caregiver.

A review of the surface and internal anatomy of the caudal canal in children

The anatomy of the sacral hiatus and caudal canal is prone to significant variation, yet studies assessing this in the pediatric population remain limited. Awareness of the possible anatomical variations is critical to the safety and success of caudal epidural blocks, particularly when image guidance is not employed. This systematic review analyzes the available evidence on the clinical anatomy of the caudal canal in pediatric patients, emphasizing surface anatomy and internal anatomical variations. A literature search using three electronic databases and standard pediatric and anatomy reference texts was conducted yielding 24 primary and seven secondary English-language sources. Appreciating that our current landmark-guided approaches to the caudal canal are not well studied in the pediatric population is important for both clinicians and researchers.

Morphologic diversities of sacral canal in children; three-dimensional computed tomographic study

BACKGROUND

Caudal block is a common technique in children for reducing postoperative pain, and there have been several reports on the variations of the sacral canal in children. However, previous studies have mainly focused on the needle trajectory for caudal block, and there is limited information on the structural variations of the sacrum in children. The purpose of this study was to analyze the anatomic variations of sacral canals in children.

METHODS

Three-dimensional computed tomographic images were analyzed. The data from the images included ① fusion of the sacral vertebral laminae and the sacral intervertebral space ② existence of the sacral cornua and ③ the types of sacral hiatus. The types of sacral hiatus were classified into 3 groups: group I (fusion of S3 or S4 vertebral laminae), group II (unfused vertebral arch with the distance of the S3 and S4 vertebral laminae < 50% of the distance between the cornua), and group III (unfused vertebral arch with the distance of the S3 or S4 vertebral laminae ≥ 50% of the distance between the cornua).

RESULTS

A total of 143 children were included in this study. All of the sacral vertebral arches were not fused in 22 children (15.4%). Cornua were not identified bilaterally in 5 (3.5%) and unilaterally in 6 (4.2%) children. In the sacral hiatus, group II and group III were identified in 22 (15.4%) and 31 (21.7%) children, respectively.

CONCLUSIONS

The sacral canal has various anatomical variations in children. Careful attention must be paid to identify the correct anatomic landmark.

Where is the apex of the sacral hiatus for caudal epidural block in the pediatric population? A radio-anatomic study

PURPOSE

Caudal epidural block (CEB), administered through the sacral hiatus, is a regional anesthetic technique commonly used in children. To facilitate and optimize pediatric CEB, morphometric data that may be important for the sacral hiatus have been obtained using multidetector computed tomography (MDCT).

METHODS

This study is the first radio-anatomic study designed to address this topic in children. Images of 79 children (39 girls and 40 boys between 1 and 9 years old) were divided into three groups according to age [group I (ages 1-3), group II (ages 4-6), and group III (ages 7-9)] and were retrospectively examined. Data were gathered via 3D volume-rendered images. Measurements included the height and width of the sacral hiatus, S2-S4 (sacral vertebra) distance, the distances between the poles of the unfused spinous process of each sacral vertebra, and the dimensions of an imaginary triangle formed between the right and left posterior superior iliac spines (PSIS) and the apex of the sacral hiatus.

RESULTS

The most frequently fused spinous process was at S2 level. The mean S2-S4 distance was 1.36 cm for group I, 1.78 cm for group II, and 2.17 cm for group III. There was not the imaginary equilateral triangle used in the method of finding the sacral hiatus for CEB, and the apex of this triangle did not occur at the standard level (S4) in most of the children. It was observed that the apex deriving from the most distal fused spinous process was at the level of S2 in one of two children.

CONCLUSION

Dural puncture is inevitable for CEB applied at the S2 level. Consequently, CEB should be applied below this level (range, 1.36-2.17 cm) from the midpoint of the interspinous distance between the PSIS (at the same level with S2) in children aged 1-9 years.

The anatomy of the sacrococcygeal cornual region and its clinical relevance

There has been no systematic study of the anatomy of the region between the sacral and coccygeal cornua. Reference texts describe an intercornual ligament connecting these structures. The aim of this study was to investigate the anatomy of this region, which may be relevant to unexplained cases of coccygeal pain (coccydynia) and local nerve blocks. The bony anatomy of the sacrococcygeal (SC) cornual region was analyzed in 33 CT scans obtained from supine adults of mostly European origin with no known SC pathology, 7 μCT scans of cadaver SC specimens, and 105 Asian Indian adult skeletons. A further five cadaver SC specimens were examined histologically. SC cornual fusion was seen in 45% of CT/μCT scans (mean age 67 years, 20 males) and in 20% of adult skeletons (78 males); there was no association with age or sex. In the absence of SC fusion, the mean intersacrococcygeal cornual gap was 7.1 ± 2.4 mm; this was bridged by an intercornual ligament composed of parallel vertical collagen fibers reinforced by elastin fibers on its anterior surface. Small nerve branches were observed adjacent to the ventral aspect of the intercornual ligament and, in one case, traversing the ligament. Ipsilateral sacral and coccygeal cornua are therefore normally bridged by an intercornual ligament that is probably innervated. The cornua are fused on one or both sides in 20-45% of adults. These findings may have implications for some cases of coccydynia and for anesthetists performing local nerve blocks.

The volume of the caudal space and sacral canal in human sacrum

INTRODUCTION

Caudal block is now- a -days a commonly used procedure for pain management and regional anaesthesia. The optimum volume of drugs required to reach the appropriate level is needed.

MATERIAL AND METHODS

For this, we studied seventy-two human sacra and measured morphometrics like height of canal and transverse diameter. We utilized these measurements for volume estimation of sacral canal and caudal space by forming a simple mathematical formula for volume half-cone.

RESULTS

We observed that mean volumes of sacral canal and caudal space were 38.26 cm(3) (23.76-62.78 cm(3)) and 14.25cm(3) (6.67-24 cm(3)) respectively.Volumes of sacral canal and caudal space had higher values in males than in females.

CONCLUSION

So, finally, it was concluded that volume of caudal space could be easily calculated this way and it was as reliable as MRI.

Approach for epiduroscopic laser neural decompression in case of the sacral canal stenosis

Epiduroscopy is very useful in the treatment of not only low back pain caused by failed back surgery syndrome, epidural scar or herniated disc but also by chronic refractory low back pain which does not respond to interventional conservative treatment including fluoroscopically-directed epidural steroid injections and percutaneous adhesiolysis. Because cauterization using a laser fiber has become recently available, a wider opening is required to enter into the sacral canal in the case of epiduroscopic laser neural decompression (ELND). However, in a few patients, it is difficult to insert a device into the epidural space due to stenosis around the opening, and there is no alternative method. Herein, we report a case where a hiatus rasp specially designed for such patients was used to perform the operation.

Caudal epidural blockade in adolescents

BACKGROUND

Various options are available for the provision of analgesia following major surgical procedures including systemic opioids and regional anesthetic techniques. Regional anesthetic techniques offer the advantage of providing analgesia while avoiding the deleterious adverse effects associated with opioids including nausea, vomiting, sedation and respiratory depression. Although used commonly in infants and children, there is a paucity of experience with the use of caudal epidural blockade in adolescents.

METHODS

We retrospectively reviewed the perioperative care of adolescents undergoing major urologic or orthopedic surgical procedures for whom a caudal epidural block was placed for postoperative analgesia.

RESULTS

The cohort for the study included 5 adolescents, ranging in age from 13 to 18 years and in weight from 42 to 71 kilograms. Caudal epidural analgesia was accomplished after the induction of anesthesia and prior to the start of the surgical procedure using 20-25 mL of either 0.25% bupivacaine or 0.2% ropivacaine with clonidine (1 μg/kg). The patients denied pain the recovery room. The time to first request for analgesia varied from 12 to 18 hours with the patients requiring 1-3 doses of analgesic agents during the initial 24 postoperative hours.

CONCLUSIONS

Our preliminary experience demonstrates the efficacy of caudal epidural block in providing analgesia following major urologic and orthopedic surgical procedures. The applications of this technique as a means of providing postoperative analgesia are discussed.

Morphometric study of sacral hiatus in adult human Egyptian sacra: Their significance in caudal epidural anesthesia

Background:

The reliability and success of caudal epidural anesthesia depends on anatomic variations of sacral hiatus (SH) as observed by various authors. SH is an important landmark during caudal epidural block (CEB).The purpose of the present study was to clarify the morphometric characteristics of the SH in human Egyptian dry sacra and pelvic radiographs and identification of nearest ony landmarks to permit correct and uncomplicated caudal epidural accesses.

Methods:

The present study was done on 46 human adult Egyptian dry sacra. The maximum height, midventral curved length, and maximum breadth of each sacrum were measured and sacral and curvature indices were calculated. According to sacral indices, sacra were divided into 2 groups (22 male and 24 female sacra). SH was evaluated in each sacrum according to its shape, level of its apex, and base according to sacral and coccygeal vertebrae, length, anteroposterior (AP) diameter at its apex, and transverse width at its base. Linear distances were measured between the apex of SH and second sacral foramina, right and left superolateral sacral crests. The distance between the 2 superolateral sacral crests also was measured.

Results:

The most common types of SH were the inverted U and inverted V (in male) and inverted V and dumbbell shaped (in female). Absent SH was observed in male group only. The most common location of SH apex was at the level of S4 in all groups of dry sacra and S3 in all groups of lumbosacral spine radiographs, whereas S5 was the common level of its base. The mean SH length, transverse width of its base, and AP diameter of its apex were 2.1±0.80, 1.7±0.26, and 0.48±0.19 cm. Female sacra showed narrower SH apex than male. The distance between the S2 foramen and the apex of the SH was 4.1±1.14, 3.67±1.21, and 4.48±1.01 cm in total, female and male sacra, respectively.

Conclusion:

Sacrum and SH showed morphometric variations in adult Egyptians. The equilateral triangle is an important guide to detect SH easily and increases the success rate of CEB. Insertion of a needle into the SH for caudal block is suggested to be done at its base to avoid the anatomic variations of its apex.

Lumbosacral transitional vertebra associated with sacral spina bifida occulta: a case report

Congenital malformations such as lumbosacral transitional vertebrae and spina bifida occulta constitute unrare anomalies and could affect the symptomatology of low back pain. A transitional vertebra is characterized by elongation of one or both transverse processes, leading to the appearance ofa sacralized fifth lumbar vertebra or a lumbarized first sacral vertebra. Furthermore, sacral spina bifida occulta is a developmental anomaly that corresponds to the incomplete closure of the vertebral column. In the present case report, we describe a case of a dried sacrum presenting a partially sacralized fifth lumbar vertebra and total spina bifida, extended from first to fifth sacral vertebra. A pseudoarthrosis is formed on the left side and the specimen could be incorporated in Castellvi's type IIa. Moreover, the incidence, morphology, clinical and surgical significance of these spinal malformations are discussed.

The caudal space in fetuses: an anatomical study

PURPOSE

The caudal epidural space is a popular site for analgesia in pediatrics. High variation in blind needle placement is common during caudal epidurals, increasing the risk of intravascular and intrathecal spread. Knowledge of safe distances and angles for accessing the caudal epidural space in premature infants can improve the safety of caudal epidural blocks.

METHODS

Thirty-nine fetuses with crown-heel length between 33 and 50 cm, corresponding to gestational age of 7-9 months, were included. The dorsal surface of the sacrum from the fourth lumbar vertebra to the tip of the coccyx was dissected, following which measurements were taken on dorsal surface and midsagittal sections. The angle of depression of the needle was measured using a goniometer following the two-step method of needle insertion.

RESULTS

Right and left sacral cornua were palpable in 23 of 39 fetuses (58.97%). Termination of dural sac was at S2 in most of the fetuses (53.84%), whereas the apex of the sacral hiatus was at S3 in most (58.97%). The distance from the apex of the hiatus to the termination of dura ranged from 3 to 13 mm; the anteroposterior distance of the canal at the apex of the hiatus ranged from 1.72 to 4.38 mm. All sacral parameters correlated with crown-heel length except inter-cornual distance, depth of canal at hiatus, and height of sacral hiatus.

CONCLUSION

Distances and angles for accessing the caudal epidural space in fetuses do not provide all parameters for safe performance of caudal epidural blocks in premature and low birth weight infants because the apex of the sacral hiatus and the termination of the dura show wide variation in location.

The evaluation of upper leg traction in lateral position for pediatric caudal block

PURPOSE

A well-functioning caudal block is an excellent adjunct to general anesthesia, but misplaced injection results in poor analgesia as well as possibility of serious morbidity. Therefore, the purpose of this study was to evaluate the effectiveness of leg traction on success rate of caudal block in lateral position in children.

METHODS

Two hundred children, age 2 months to 6 years, ASA I and II, who underwent lower abdominal surgeries were randomized in prospective controlled clinical trial study in two groups. After induction of General anesthesia, the caudal block was performed in the lateral position with upper leg traction (L-T-) or with the standard position (S-P) (leg flexed 90°). Hemodynamicchanges, movement of lower extremity in response to surgical stimulus were evaluated.

RESULTS

There was no significant difference in caudal block's success rate between two groups at first attempt (P=0.25). In group (S-P) the procedure was successful in 60% of cases at first attempt, 25% at second,10% at third attempt and 5% failure of caudal block, whereas in the first group it was 75%, 20%, 1% and 4% of cases respectively. There were no significant differences in heart rate and blood pressure changes between two groups (P>0.05).

CONCLUSION

The success rate of pediatric caudal block in upper leg traction did not differ from that of the standard position.