Sacral Foramen Research Articles

Sacral Neuromodulation: Device Improvement and Current Applications in Urology.

Sacral neuromodulation (SNM) offers a therapeutic approach to urological patients suffering from idiopathic overactive bladder (OAB) syndrome, with or without incontinence and non-obstructive urinary retention (NOR), who are not responding to or are not compliant with conservative or medical therapies. The exact mechanism of action of SNM is not fully understood but modulation of the spinal cord reflexes and brain networks by peripheral afferents is regarded as the main pathway. Over the years, surgical techniques improved, leading to the development of the modern two-stage implantation technique. The quadripolar lead is positioned percutaneously under fluoroscopy guidance through the third sacral foramen following the trajectory of S3. The procedure can be performed under local or general anesthesia with the patient in prone position. Current applications of sacral neuromodulation in urology are increasing thanks to the recent improvements of the devices that make this a valuable option not only in conditions such as overactive bladder and non-obstructing urinary retention but also neurogenic lower urinary tract dysfunction.

Evaluation of Three Imaging Methods to Quantify Key Events in Pelvic Bone Metastasis.

The purpose of this study is to compare turbo spin echo diffusion-weighted images in radial trajectory (BLADE DWI) with multi-shot echoplanar imaging (RESOLVE DWI) for imaging the metastatic lesion in the pelvic bone to find a correlation between ADC values and standardized uptake values (SUVs) of FDG uptake in PET/CT. The study also seeks to compare the values of metastatic lesions with those of benign bone lesions, specifically red marrow hyperplasia. The retrospective IRB-approved study included patients with bone metastasis and red marrow hyperplasia in the pelvic bone who underwent 3.0 T MRI with BLADE/RESOLVE DWI sequences and F-18 FDG PET/CT within one month. BVC (best value comparator) was used in determining the nature of bone lesions. Apparent diffusion coefficient (ADC) and standardized uptake value (SUV) were measured by a radiologist and a nuclear medicine physician. MRI image quality was graded with a Likert scale regarding the visualization of the sacroiliac joint, sacral neural foramen, hamstring tendon at ischial tuberosity, and tumor border. Signal-to-noise ratio (SNR) and imaging time were compared between the two DWIs. Mean, peak, and maximum SUVs between metastatic and benign red marrow lesions were compared. SUVs and ADC values were compared. AUROC analyses and cut-off values were obtained for each parameter. Mann-Whitney U, Spearman's rho, and Kolmogorov-Smirnov tests were applied using SPSS. The final study group included 58 bone lesions (19 patients (male: female = 6:13, age 52.5 ± 9.6, forty-four (75.9%) bone metastasis, fourteen (24.1%) benign red marrow hyperplasia). ADCs from BLADE and RESOLVE were significantly higher in bone metastasis than red marrow hyperplasia. BLADE showed higher ADC values, higher anatomical scores, and higher SNR than RESOLVE DWI (p < 0.05). Imaging times were longer for BLADE than RESOLVE (6 min 3 s vs. 3 min 47 s, p < 0.05). There was a poor correlation between ADC values and SUVs (correlation coefficient from 0.04 to 0.31). The AUROC values of BLADE and RESOLVE MRI ranged from 0.892~0.995. Those of PET ranged from 0.877~0.895. The cut-off ADC values between the bone metastasis and red marrow hyperplasia were 355.0, 686.5, 531.0 for BLADE min, max, and average, respectively, and 112.5, 737.0, 273.0 for RESOLVE min, max, and average, respectively. The cut-off SUV values were 1.84, 5.01, and 3.81 for mean, peak, and max values, respectively (p < 0.05). Compared with RESOLVE DWI, BLADE DWI showed improved image quality of pelvic bone MRI in the aspect of anatomical depiction and SNR, higher ADC values, albeit longer imaging time. BLADE and RESOLVE could differentiate bone metastasis and red marrow hyperplasia with quantifiable cut-off values. Further study is necessary to evaluate the discrepancy between the quantifiers between PET and MRI.

Efficacy and safety of different nerve block methods for the treatment of pudendal neuralgia

Objective: To identify efficacy and safety of pudendal nerve block in tubing through the third posterior sacral foramen for the treatment of pudendal neuralgia (PN). Methods: A retrospective study with 222 PN patients was conducted in the Department of Pain Management of Beijing Tsinghua Changgung Hospital from January 2020 to April 2023. These patients were divided into two groups based on their treatment methods: pudendal nerve block in tubing through the third posterior sacral foramen (observation group, n=101) and ultrasound-guided pudendal nerve block (control group, n=121). Primary outcome measure was the 90-day postoperative pain relief rate. Secondary outcome measures included visual analog scale (VAS) at 1, 7, 14, 30 and 90 d after surgery, the incidence of tramadol uses after surgery, postoperative self-rating anxiety scale (SAS) scores and the incidence of adverse events. Factors that influenced pain relief within 90 days after surgery were analyzed by using binary logistic regression analysis. Results: Observation group included 34 males and 67 females, aged (49.8±16.0) years old. Control group included 38 males and 83 females, aged (43.7±14.0) years old. The 90-day postoperative pain relief rate of the observation group patients was 38.6% (39/101), which was higher than the 24.0% (29/121) of the control group patients (P=0.018). Both the observation group and the control group showed an interaction effect of time and group after treatment for VAS scores (both P<0.05). In intra-group comparison, the VAS scores at 1, 7, 14, 30 and 90 d after treatment in both groups were lower than those before treatment (all P<0.05). In inter-group comparison, the differences of the VAS scores were not statistically significant in the observation group compared with those in the control group at 1, 7, 14, 30 and 90 d after surgery (all P>0.05). The SAS score of the observation group at 90 d after surgery was 51.5±6.2, which was lower than the 53.4±5.8 of the control group (P=0.022). There was no statistically significant difference in the incidence of postoperative tramadol uses and adverse events between the two groups (both P>0.05). Pudendal nerve block in tubing through the third posterior sacral foramen was a protective factor for pain postoperative relief in PN patients at 90 d after surgery (OR=1.92, 95%CI: 1.05-3.48, P=0.033). Conclusion: Pudendal nerve block in tubing through the third posterior sacral foramen is a safe and effective minimally invasive treatment. It has a higher postoperative pain relief rate within 90 d after surgery, without increasing the uses of postoperative rescue analgesics and the incidence of adverse events.

Comparative Evaluation of Caudal Epidural Method to Ultrasound-Guided S1 Transforamen Block in Patient's Lumbar Discectomy with Failed Back Syndrome Symptoms: A Double-Blind Clinical Trial.

Post-lumbar surgery syndrome (PLSS) refers to persistent or recurrent pain following spinal surgery with an unknown cause. It is commonly associated with epidural fibrosis (EF). Some studies suggest that epidural steroid injection (ESI) can effectively alleviate pain in PLSS, particularly when targeting the S1 nerve root using S1 transforaminal epidural steroid injection (S1-TFESI). A key factor in a successful block is accurately visualizing the first dorsal sacral foramen, and the needle's destination is the dorsal S1 foramen. Although S1-TFESI is often performed under fluoroscopy through the transforaminal route, an alternative to reduce radiation exposure is ultrasound guidance. This study aimed to compare the efficacy of ultrasound-guided caudal epidural steroid injection (CESI) and S1-TFESI in PLSS patients. A randomized double-blinded clinical trial was conducted involving 52 PLSS patients who were randomly assigned to either the CESI group or the S1-TFESI group. The patients were positioned prone. A linear transducer with a curve at a low frequency (2 - 5 MHz) was used to visualize the area. An aseptically prepared puncture site was used to insert a 2- to 5-MHz curved ultrasound probe with an ultrasound gel to identify the articular processes of the lower lumbar vertebrae and the posterior sacral surface. The probe was then positioned longitudinally to the para-sacral area, about 2 cm lateral to the midline. The articular process represented the L5/S1 level at the farthest caudal side, and the S1 posterior sacral foramen was represented by the concavity at the posterior sacral surface that was somewhat caudal. The probe was angled caudally to provide enough room for the needle to enter the S1 foramen. The injection site for the needle tip was the S1 foramen. A combination of triamcinolone (40 mg, 1 mL), normal saline (2 mL), and ropivacaine (0.2%) was administered. For TFS1 ESI, 5 mL of the combination was used. For CESI, the sacral hiatus was palpated in the prone position, and a linear high-frequency transducer was placed transversely to obtain a transverse view of the sacral hiatus. A combination of triamcinolone 40 mg and ropivacaine (0.2%) totaling 10 mL was employed. The Numerical Rating Scale (NRS) and Oswestry Disability Index (ODI) were used to assess patients' preoperative and postoperative conditions, and adverse events were recorded. Follow-up was conducted one week and one month after the procedures. In both groups, NRS and ODI scores decreased at different time points after treatment, compared to baseline (P < 0.001). The CESI group had lower median ODI scores after one week and one month, although this difference did not reach statistical significance (P = 0.334). Despite similar baseline NRS ratings, the CESI group had statistically significantly lower mean NRS scores at one week and one month (P < 0.001). The current study demonstrated that both CESI and TFESI treatments for PLSS following lumbar discectomy are effective and safe. These procedures can alleviate pain and reduce disability. Although the success rates of the two procedures are comparable, CESI appears to be more successful in reducing pain at the one-week and one-month follow-up.

Surgical Management of Unstable U-Shaped Sacral Fractures and Tile C Pelvic Ring Disruptions: Institutional Experience in Light of a Narrative Literature Review.

Unstable U-shaped sacral fractures and vertical shear Tile C pelvic ring disruptions are characterized by rare lesions occurring in patients with severe trauma. Because the initial damage-control resuscitation primarily aims to stop life-threatening bleeding, emergency treatment often includes an anterior external pelvic fixator. Delayed surgery is mandatory to allow early mobilization, reduce mortality, and improve functional outcomes. Regarding U-shaped sacral fractures, although Roy-Camille type 1 U-shaped sacral fractures can be treated with iliosacral screws, types 2 (posteriorly displaced, equivalent to AO Spine C3) and 3 (anteriorly displaced, equivalent to AO Spine C3) fractures require spinopelvic triangular fixation. Besides, proper reduction of type 2 and some type 3 sacral fractures is mandatory to prevent wound complications. In patients with neurological deficits, the need for sacral laminectomy is left at the discretion of the surgeon, given the indirect decompression already obtained with fracture reduction. Tile C pelvic disruptions with posterior ring injury located lateral to the sacral foramen can be treated with either iliosacral screws or triangular spinopelvic fixation, combined with anterior pelvic fixation. Conversely, Tile C pelvic disruptions with posterior ring injury located at, or medial, to the sacral foramen (Denis zone II or III) induce vertical lumbosacral instability and thus require spinopelvic triangular fixation with anterior pelvic osteosynthesis. Although minimally invasive techniques have been developed, open surgeries are still required for inexperienced operators and in case of major displacement. The complication rate reaches approximately 33.33% of the cases, and complications include hardware malposition, wound infection or dehiscence, hardware prominence, and sometimes hardware failure.

Applied anatomy of female pelvic plexus for nerve-sparing radical hysterectomy(NSRH)

BackgroundNerve-sparing radical hysterectomy(NSRH)has the advantage of reducing postoperative complications and improving postoperative quality of life. The separation and protection of the pelvic plexus in NSRH is extremely important and challenging.Methods24 female cadaveric hemipelves were dissected. Morphologic patterns and compositions of pelvic plexus as well as relationship of pelvic plexus to the surrounding structures were observed and documented.ResultsTwo patterns of superior hypogastric plexus were observed, including fenestrated and cord-like shape. The origin of bilateral hypogastric nerves were inferiorly to upper margin of promontory about 1.6 ± 0.1 cm and parallel to the ureter in front of the sacrum. Pelvic splanchnic nerves(PSN)from the second sacral nerve, the third sacral nerve and the forth sacral nerve were observed combing with the hypogastric nerves within the lateral rectal ligament. The sacral sympathetic trunk can be identified anteriorly or medially to the anterior sacral foramen. We identified the boundaries of pelvic plexus as following: the upper margin is formed by the PSNs from the third sacral nerve, posterior margin by inferior rectal artery, and anteriorly by vesical venous plexus. The uterine branches from pelvic plexus were observed accompanying with uterine artery, while other branches were inferiorly to the artery. The PSNs were located beneath the deep uterine veins within the cardinal ligament. The upper margin of pelvic plexus was observed directly approach to urinary bladder within the vesico-vaginal ligament as a single trunk accompanying with ureter, between the middle and inferior vesical veins.ConclusionsOur study clarified the intricate arrangement, distribution and relationship of female pelvic plexus and the related structures to provide reference index for NSRH application. The innervation patterns of bladder and uterine were clarified, and by tracing these visceral branches of pelvic plexus, we suggest several new important land markers for NSRH.

Biomechanical Comparison of Double 2.3-mm Headless Cannulated Self-Compression Screws and Single 3.5-mm Cortical Screw in Lag Fashion in a Canine Sacroiliac Luxation Model: A Small Dog Cadaveric Study.

The aim of this study was to evaluate the feasibility of safe positioning of double 2.3-mm headless cannulated self-compression screws (HCS) in a small dog cadaveric sacroiliac luxation model and to compare the static rotational biomechanical properties of fixation repaired using two different screw systems with a minimally invasive osteosynthesis technique: double 2.3-mm HCS and a single 3.5-mm standard cortical screw placed in a lag fashion. A unilateral small dog sacroiliac luxation model was stabilized using double 2.3-mm HCS (n = 11) or a single 3.5-mm cortical screw (n = 11). Radiographic and computed tomography (CT) imaging analyses and biomechanical testing of rotational force on the sacroiliac joint of both fixations were performed. The maximum load at failure and failure modes of each fixation were recorded and compared. Fluoroscopically guided percutaneous application of double HCS was safe in a unilateral sacroiliac luxation model in small dogs without violation of the vertebral and ventral sacral foramen. Furthermore, resistance to rotational force applied on fixation of the sacroiliac joint repaired with double 2.3-mm HCS estimated by maximum failure load was significantly higher than that of a single 3.5-mm cortical screw (p < 0.001). Although this was an experimental cadaveric study, based on our results, the use of smaller double HCS may be beneficial as an alternative to the conventional single lag screw for stabilization of sacroiliac luxation in small dogs.

High uterosacral ligament suspension in radical hysterectomy: a step-by-step procedure to prevent pelvic organ prolapse.

Given the younger age of cervical cancer patients and improved postoperative survival, postoperative quality of life should be a reason for concern, particularly given the prevalence of pelvic floor dysfunction. High uterosacral ligament suspension (HUS) has been deemed the more consistently successful surgery for the treatment of mid-pelvic abnormalities. HUS intraoperatively prevents pelvic floor dysfunction effectively. We demonstrate the steps of surgery using surgical video and photographs. The uterosacral ligament is fan shaped and connected to the fascial and extraosseous membranes on the surface of the anterior sacral foramen of the 2nd, 3rd, and 4thsacral vertebrae. Given that the uterosacral ligament was fan-shaped, the fan-shaped suture with three stitches was more compatible with the original anatomy. Thirty patients with HUS who underwent thorough hysterectomy had no complications, operation time 230.82 ± 43.61min, and blood loss 62.32 ± 37.25ml. The urinary catheter was successfully removed 1 week after the operation, and no pelvic organ prolapse, including vaginal anterior and posterior wall prolapse, or rectocele, occurred after 3 years of follow-up. The uterosacral ligament fulfills the role of supporting, pulling, and suspending the uterus. We should exploit the advantage of fully exposing the uterosacral ligament in radical hysterectomy. Performing HUS to prevent pelvic organ prolapse following radical hysterectomy is a procedure worthy of investigation and promotion.

Prevalence of Accessory Sacroiliac Joint and Its Clinical Significance

Objective: To determine the prevalence of the accessory sacroiliac joint (ASIJ) on both computed tomography (CT) images and dry bones and ultimately, to contribute to the literature.&#x0D; Materials and Methods: CT images archived in the Radiology department of Gaziantep University Medical Faculty obtained from 145 individuals (104 males and 41 females) as well as 92 sacral bones were examined. &#x0D; Results: The prevalence of ASIJ among 92 sacral bones was 15.2%. The ASIJ was more commonly (52%) located at the posterior portion of the SIJ at the level of the second dorsal sacral foramen. In 48% of the bones, ASIJ was identified just above the first dorsal sacral foramen. Unilateral ASIJ was observed in 10.8% and bilateral ASIJ in 4.4% of the sacral bones. On CT images, ASIJ was found in 7.8% of the males and 7.2% of the females. The total prevalence of sacroiliac joint variations was 28.9%, and 6.8% of them were ASIJs.&#x0D; Conclusion: It should be kept in mind that ASIJ may be a source of arthritis and chronic hip pain. The presence of ASIJ should be sought through imaging studies for early diagnosis of ASIJ.

A Straightforward 3-Step Method for Identifying the Sacroiliac Joint Using Ultrasonography.

Blind injections of the proximal sacroiliac joint have a low success rate. Blind injections of the distal, on the other hand, are risky due to the proximity of the sacral foramen. Therefore, ultrasound guidance is required in sacroiliac joint injections.

Feasibility of percutaneous dural sac puncture via a posterior trans-sacral foraminal conduit approach: a CT morphometric analysis.

We assess the theoretical feasibility of percutaneous posterior sacral foramen (pSF) needle puncture of the sacral dural sac (DS) by studying the three-dimensional imaging anatomy of pSFs relative to the sacral canal (SC). On CT images of 40 healthy subjects, we retrospectively studied sacral alae passageways from SC to pSFs in all three planes to determine if an imaginary spinal needle could theoretically traverse S1 or S2 pSFs in a straight path toward DS. If not straight, we measured multiplane angulations and morphometrics of this route. We found no straight connections between S1 or S2 pSFs and SC. Instead, there were bilateral spatially complex dorsoventral M-shaped "foraminal conduits" (FCs; common, ventral, and dorsal) from SC to anterior SFs and pSFs that would prevent percutaneous straight needle puncture of the DS. This detailed knowledge of the sacral FCs will be useful for accurate imaging interpretation and interventional procedures on the sacrum.

Measurement of S1 foramen depth for ultrasound-guided S1 transforaminal epidural injection

Ultrasound-guided first sacral transforaminal epidural steroid injection (S1 TFESI) is a useful and easily applicable alternative to fluoroscopy or computed tomography (CT) in lumbosacral radiculopathy. When a needle approach is used, poor visualization of the needle tip reduces the accuracy of the procedure, increasing its difficulty. This study aimed to improve ultrasound-guided S1 TFESI by evaluating radiological S1 posterior foramen data obtained using three-dimensional CT (3D-CT). Axial 3D-CT images of the pelvis were retrospectively analyzed. The radiological measurements obtained from the images included 1st posterior sacral foramen depth (S1D, mm), 1st posterior sacral foramen width (S1W, mm), the angle of the 1st posterior sacral foramen (S1A, °), and 1st posterior sacral foramen distance (S1ds, mm). The relationship between the demographic factors and measured values were then analyzed. A total of 632 patients (287 male and 345 female) were examined. The mean S1D values for males and females were 11.9 ± 1.9 mm and 10.6 ± 1.8 mm, respectively (P < 0.001); the mean S1A 28.2 ± 4.8° and 30.1 ± 4.9°, respectively (P < 0.001); and the mean S1ds, 24.1 ± 2.9 mm and 22.9 ± 2.6 mm, respectively (P < 0.001); however, the mean S1W values were not significantly different. Height was the only significant predictor of S1D (β = 0.318, P = 0.004). Ultrasound-guided S1 TFESI performance and safety may be improved with adjustment of needle insertion depth congruent with the patient's height.

Radiological Evaluation of Pelvic Morphology for S2 Alar-Iliac Screw Insertion in the Japanese Samples: A Retrospective Cohort Study.

S2 alar-iliac screw (S2AIS) insertion for lumbosacral fixation is becoming a common procedure for deformity surgeries. However, studies that have reported the anatomy and morphometric features of the pelvis for S2AIS insertion in the Japanese samples are scarce. This study aimed to elucidate the morphometric features of the pelvis regarding S2AIS insertion in the Japanese samples. We used 60 computed tomography scans of the pelvis (30 men and 30 women). The entry point for the S2AIS was determined as 1-mm lateral and 1-mm distal to the S1 dorsal sacral foramen. We resliced the plane in which the pelvis was sectioned obliquely from this entry point to the anterior inferior iliac spine in the sagittal plane. We bilaterally placed the shortest and longest virtual S2AISs in this plane using a 4-mm margin. We analyzed the length, angle, and safety of the determined trajectory and compared these measurements according to sex and age. The median longest and shortest screw lengths were 108.1 and 103.3 mm, respectively. The median longest and shortest distances from the entry point to the sacroiliac joint were 31.2 and 28.2 mm, respectively. The median smallest and largest lateral angulations were 40.7° and 47.3°, respectively. The median angle range was 4.2°. The median caudal angulation was -2.8°. The median shortest and longest distances from the S2AISs to the acetabular roof were 23.5 and 27.4 mm, respectively. The median distance from the S2AISs to the sciatic notch was 23.1 mm. Assuming the insertion of screw with a diameter of 8 mm, S2AIS insertion was difficult in 32 of 120 (27%) screws because the dorsal cortex of the sacrum was damaged. Screw length and lateral angulation were similar to those in previous studies. Insertion difficulty occurred in 27% of screws.

Novel anatomical findings with implications on the etiology of the piriformis syndrome

PurposeThe cause of the piriformis-related pelvic and extra-pelvic pain syndromes is still not well understood. Usually, the piriformis syndrome is seen as extra-pelvic sciatica caused by the entrapment of the sciatic nerve by the piriformis in its crossing through the greater sciatic foramen. However, the piriformis muscle may compress additional nerve structures in other regions and cause idiotypic pelvic pain, pelvic visceral pain, pudendal neuralgia, and pelvic organ dysfunction. There is still a lack of detailed description of the muscle origin, topography, and its possible relationships with the anterior branches of the sacral spinal nerves and with the sacral plexus. In this research, we aimed to characterize the topographic relationship of the piriformis with its surrounding anatomical structures, especially the anterior branches of the sacral spinal nerves and the sacral plexus in the pelvic cavity, as well as to estimate the possible role of anatomical piriformis variants in pelvic pain and extra-pelvic sciatica.MethodsHuman cadaveric material was used accordingly to the Swiss Academy of Medical Science Guidelines adapted in 2021 and the Federal Act on Research involving Human Beings (Human Research ACT, HRA, status as 26, May 2021). All body donors gave written consent for using their bodies for teaching and research. 14 males and 26 females were included in this study. The age range varied from 64 to 97 years (mean 84 ± 10.7 years, median 88).Resultsthree variants of the sacral origin of the piriformis were found when referring to the relationship between the muscle and the anterior sacral foramen. Firstly, the medial muscle origin pattern and its complete covering of the anterior sacral foramen by the piriformis muscle is the most frequent anatomical variation (43% in males, 70% in females), probably with the most relevant clinical impact. This pattern may result in the compression of the anterior branches of the sacral spinal nerves when crossing the muscle.ConclusionsThese new anatomical findings may provide a better understanding of the complex piriformis and pelvic pain syndromes due to compression of the sacral spinal nerves with their somatic or autonomous (parasympathetic) qualities when crossing the piriformis.

Sacral hiatus anatomical variations and clinical relevance in caudal epidural block

Objective: For the management of perioperative pain control during procedures like genitourinary surgery and labor pain instances when the sacral epidural space technique is utilized for the application of analgesia, caudal epidural anesthesia (CEB) is frequently used. CEB is an anesthetic that is injected through the sacral hiatus (SH) into the sacral canal. Anatomical features of sacral hiatus that are in-depth are needed for the best possible access to the sacral epidural area. By employing the sacral bone as a point of reference to failure parameters for evaluating caudal epidural anesthesia and refining the success factors in practice, this study intends to explore the anatomical structures and variations of the Sacral hiatus. Material and methods: 85 sacral bones had their alignment points measured precisely morphometrically. Virtual calipers were used to take the readings were used to evaluate those utilizing photogrammetric techniques. Results: Inverted U was the most frequent sacral hiatus form reported (33.32%), although bifida and 6.8% 3.44% of cases frequently missing sacral hiatus were also seen. The mean Sacral hiatus length was 28.67.0 mm, the mean intracorneal distance was 13.472.68 mm, and the mean gap between the apex of the Sacral hiatus and S2 sacral foramen was 34.677.08 mm.

Distal sacral nerve roots severed by a fragility fracture of the sacrum: a case report

BackgroundOwing to the aging population, fragility fractures of the pelvis are occurring more frequently. Fixation of the fracture and stabilization of the pelvic ring usually provide good clinical results. A case of distal sacral nerve roots severed by a fragility fracture of the sacrum is presented.Case presentationA 62-year-old Japanese woman with schizophrenia with low back pain, gait disorder, dysuria, and fecal incontinence presented to an emergency department, and plain X-rays showed no findings. She also complained of dysuria, and neurogenic bladder and cystitis were diagnosed. One month later, she was admitted to a psychiatric hospital for exacerbation of schizophrenia. In hospital, she had a urethral catheter inserted and spent 3 months in bed. She was referred to our orthopedic department because a gait disorder was discovered after her mental condition improved and she was permitted to walk. On examination, she could not walk and had decreased sensation from the buttocks to both posterior thighs and around the anus and perineum. Manual muscle testing of her lower limbs showed mild weakness of about 4 in bilateral flexor hallucis longus and gastrocnemius, and bilateral Achilles tendon reflexes were lost. Her anal sphincter did not contract, and urinary retention continued after urethral catheter removal. Imaging examinations showed an H-shaped sacral fracture consisting of a transverse fracture with displacement of the third sacral vertebra and vertical fractures of the bilateral sacral wings, with severe stenosis of the spinal canal at the site of the transverse fracture. The patient was diagnosed as having bladder and rectal dysfunction due to a displaced, unstable sacral fracture. First to third sacral laminectomy and alar–iliac fixation using percutaneous pedicle screws and sacral alar–iliac screws were then performed. The bilateral distal sacral nerve roots (S3, S4, S5) were completely severed at the second to third sacral levels, but bilateral second sacral nerve roots were not compressed from the bifurcation to the sacral foramen. Postoperatively, bladder and rectal dysfunction remained, but the low back pain was alleviated. Two weeks postoperatively, she could walk with a walker and was discharged. Three months after the operation, bone fusion of the fracture was observed.ConclusionsIn cases of bladder–rectal dysfunction with low back pain, the possibility of sacral fracture should be considered, and computed tomography, magnetic resonance imaging, and X-ray examinations should be performed. Even sacral fractures without displacement require attention because they can cause serious injury in the event of a nerve root being severed if not diagnosed early and given appropriate treatment.

Penile Erection Induced by Stimulation of Sacral S1/S2 Spinal Root in Cats

ObjectiveThis study aimed at determining whether stimulation of sacral spinal roots can induce penile erection in cats. Materials and MethodsIn anesthetized cats, a 20-gauge catheter was inserted into the corpus cavernosum to measure the penile pressure. Stimulus pulses (5–80 Hz, 0.2 ms) were applied through bipolar hook electrodes to sacral ventral roots alone or to combined ventral and dorsal roots of a single S1–S3 segment to induce penile pressure increases and penile erection. ResultsStimulation of the S1 or S2 ventral root at 30 to 40 Hz induced observable penile erection with rigidity and the largest increase (169 ± 11 cmH2O) in penile pressure. Continuous stimulation (10 minutes) of afferent and efferent axons by simultaneous stimulation of the S1 or S2 dorsal and ventral roots at 30 Hz also produced a large increase (190 ± 8 cmH2O) in penile pressure that was sustainable during the entire stimulation period. After a complete spinal cord transection at the T9–T10 level, simultaneous stimulation of the S1 or S2 dorsal and ventral roots induced large (186 ± 9 cmH2O) and sustainable increases in penile pressure. ConclusionThis study indicates the possibility to develop a novel neuromodulation device to restore penile erection after spinal cord injury using a minimally invasive surgical approach to insert a lead electrode through the sacral foramen to stimulate a sacral spinal root.

Delineating the Subarachnoid Space in the Adult Lumbosacral Spine Using Computed Tomographic Myelography: An Aid for Clinical Target Volume Delineation in Craniospinal Irradiation

PurposeOur aim was to characterize the patterns of cerebrospinal fluid (CSF) extension in the lumbosacral spine using computed tomography (CT) myelograms to provide an evidence base for clinical target volume (CTV) definition in adults receiving craniospinal irradiation. Methods and MaterialsThis was a retrospective analysis of diagnostic CT lumbar myelograms performed in 30 patients between the ages of 22 and 50. Lateral extension of CSF beyond the thecal sac was measured along each lumbar and sacral nerve root to the nearest millimeter, as was the distance of inferior extension of CSF beyond the caudal end of the thecal sac. Each patient's lateral and inferior CSF extensions were mapped onto a standardized CT data set to create a model target volume in the lumbosacral spine that would contain the aggregate observed CSF distributions from the analyzed CT myelograms. The median extension distances, interquartile ranges, and 90th percentile for distance at each level were calculated. ResultsThe median lateral extension of CSF along nerve roots beyond the thecal sac—as measured perpendicular to the longitudinal axis—increased from 0 mm (interquartile range [IQR], 0-4 mm) at L1 to 8 mm (IQR, 6-12 mm) at S1 and 0 mm (IQR, 0-0 mm) at S4. The 90th percentile ranged from 5 to 14 mm laterally, with a pattern partially extending into the S1 and S2 sacral foramen. Median CSF extension inferior to the caudal sac was 5 mm (IQR, 2-8 mm), with 90% of patients within 12 mm. An atlas was generated to guide CTV delineation for highly conformal radiation techniques. ConclusionThese results provide information on patterns of CSF extension in the lumbosacral spine of adults and can serve as a model for CTV guidelines that balance comprehensive coverage of the CSF compartment while minimizing the dose to nontarget tissues.

Radiologically anatomic measurement analysis for the third sacral foramen and an efficient implantation protocol for sacral neuromodulation.

To define radiologically anatomic measurements for the S3 foramen and develop an efficient and straightforward implantation protocol for sacral neuromodulation (SNM) in a southern Chinese population. We retrospectively reviewed 793 adults without sacrococcygeal abnormalities or bony injury. We generated CT-derived three-dimensional volumetric models and collected radiologically anatomic measurements of S3 foramen. A multiple generalized linear regression model was applied to evaluate implantation protocol for SNM. Height, weight, and sacral height were significantly different between enrolled patients based on sex (p < 0.001 for all), while age and sacral width were similar. The measurements L1, L2, A1, and A2 on both sides were similar, while based on sex, those of L1, A1, A2 showed significant differences [7.02 ± 0.90 (M) vs. 6.10 ± 0.99 cm (F) (p < 0.001); 83.05 ± 6.23 (M) vs. 82.08 ± 7.53° (F) (p = 0.005); and 13.31 ± 5.69 (M) vs. 11.97 ± 4.91° (F) (p < 0.001), respectively]. The multiple generalized linear regression model demonstrated that sex was a common independent factor for estimating L1, L2, A1, A2, while the consistency rate between the estimated model and actual measurements was poor. The measurements L1, L2, A1, and A2 were approximately 7.0 cm (M) versus 6.1 cm (F), 1.8 cm (M) versus 1.8 cm (F), 83° (M) versus 82° (F), and 13° (M) versus 12° (F), respectively. This retrospective study indicates that the radiologically anatomic measurements for the S3 foramen have unique characteristics. Our study provides an efficient and straightforward implantation protocol for SNM, improving its use in China.

Postoperative Pain Relief With Ultrasound-Guided Dorsal Sacral Foramen Block for Foot and Ankle Surgeries

This case series describes the use of ultrasound (US)-guided dorsal sacral foraminal block (DSFB) for providing postoperative analgesia in six patients who underwent foot and ankle surgeries under spinal anesthesia. Postoperatively, all of them received a US-guided DSFB at the level of the brim of the second sacral foramina (SF2). Needle placements were confirmed with fluoroscopic (FL) images and injected radiocontrast defined the diffusion with a postoperative CT scan. The images obtained depicted ipsilateral spread in the sacral epidural space, sacral nerve roots, and plexus. The US-guided DSFB could be effectively used as an alternative method for postoperative pain relief after foot and ankle surgery.