Sacral neuromodulation in patients with detrusor underactivity: Is biological sex an indicator?

OBJECTIVES: This study aimed to report sacral neuromodulation (SNM) outcomes in detrusor underactivity (DU). METHODS: A multicentric, multinational, retrospective case series was conducted between March 2017 and June 2021 in three different referral centers. Initial test phase stimulation included either a percutaneous nerve evaluation (PNE) or an advanced lead evaluation test phase (ALTP) before permanent SNM implantation. The test phases were performed under local anesthesia, either in the outpatient (PNE) or operating room (ALTP), in the prone position, which was implanted in the third or fourth sacral foramina under fluoroscopic guidance. Patients with favorable response to the initial test phase during the first 2 weeks underwent the implantable pulse generator (IPG) implantation (Medtronic neurostimulation generator device InterStim™). Favorable response was defined as ≥ 50% improvement in symptoms, frequency of clean intermittent catheterization (CIC) and/or decrease in postvoid residual (PVR), increase in voided volume, or improvement in bladder voiding efficiency (BVE) based on the bladder diary. RESULTS: Fifty-eight patients were recruited with a mean age of 39.95 ± 15.28 years. Among the 58 cases, 36 (62.1%) patients responded to the initial stage. Of these, 12 patients (30.8%) with non-neurogenic etiology and nine patients (52.9%) with neurologic etiology did not respond to the initial test phase; thus, they did not undergo full implantation (p = 0.141). Voided volume, PVR, and the median maximum flow rate (Qmax) improved significantly (p < 0.001) in both sexes; however, there was no statistical difference between both genders. Most female cases (78.3%), and nearly half of the men (51.4%), responded to the test phase and were candidates for the IPG phase. Among the 35 cases who underwent IPG, 27 patients (72.2% of males, and 77.8% of females; p = 0.700) had a favorable response to IPG. 46.6% of patients had a successful outcome at the end of the study. CONCLUSION: This multicentric study showed that SNM effectively and safely provided symptom improvement in refractory DU in males similar to females which is an important finding as previously it has been suggested that SNM works better in nonobstructive urinary retention in women and not in women.

Assessment of sacral spinal excitability using stimulus-response curves of the bulbocavernosus reflex.

OBJECTIVE: To analyze and quantify sacral spinal excitability through bulbocavernosus reflex (BCR) stimulus-response curves. METHODS: Thirty subjects with upper motor neuron lesions (UMN) and nine controls were included in this prospective, monocentric study. Sacral spinal excitability was assessed using stimulus-response curves of the BCR, modeled at different bladder filling volumes relative to the desire to void (as defined by the International Continence Society) during a cystometry. Variations in α (i.e. the slope of the stimulus-response curve) were considered as an indicator of the modulation of sacral spinal excitability. RESULTS: In all subjects, α increased during bladder filling suggesting the modulation of spinal sacral excitability during the filling phase. This increase was over 30% in 96.7% of neurological subjects and 88.9% of controls. The increase was higher before the first sensation to void in the neurological population (163.15%), compared to controls, (29.91%), p < 0.001. CONCLUSIONS: We showed the possibility of using BCR stimulus-response curves to characterize sacral spinal response with an amplification of this response during bladder filling as well as a difference in this response amplification in patients with UMN in comparison with a control group. SIGNIFICANCE: BCR, through stimulus-response curves, might be an indicator of pelvic-perineal exaggerated reflex response and possibly a tool for evaluating treatment effectiveness.

Validity of the EOS-determined pelvic parameters and orientation with pelvic positional variation: a phantom study.

The EOS is a medical imaging system that incorporates simultaneous orthogonal images, producing three-dimensional (3D) reconstructions of the whole skeletal system in various functional positions. Despite growing interest in the pelvic 3D position, the validity of the EOS has not yet been well studied. We investigated the trueness and precision of EOS imaging for pelvic parameters and orientation and assessed whether the measurement using the EOS was affected by the pelvic orientation itself. The orientation of the anterior pelvic plane and pelvic parameters of a custom-made pelvic phantom were measured by three raters using the EOS, and the measurements obtained were compared with the true values. The standard deviations of the measurement errors were 3.23°, 0.26°, 0.23°, 2.98°, 0.88°, and 3.22° for flexion, obliquity, rotation, pelvic incidence, spinopelvic tilt, and sacral slope, respectively. The root-mean square averages of the standard deviation of each measurement were 4.05°, 0.41°, 0.28°, 4.80°, 0.99°, and 5.13°, respectively. The measurement errors for sacral slope correlated significantly with geometric means of flexion, obliquity, and rotation (r = 0.364, p = 2.67 × 10-11). The EOS rendered accurate and reliable measurements regarding pelvic 3D position, even with positional variation, but positional variation could affect measurements of sacral slope.

Calibration and validation of a novel hybrid model of the lumbosacral spine in ArtiSynth-The passive structures.

In computational biomechanics, two separate types of models have been used predominantly to enhance the understanding of the mechanisms of action of the lumbosacral spine (LSS): Finite element (FE) and musculoskeletal multibody (MB) models. To combine advantages of both models, hybrid FE-MB models are an increasingly used alternative. The aim of this paper is to develop, calibrate, and validate a novel passive hybrid FE-MB open-access simulation model of a ligamentous LSS using ArtiSynth. Based on anatomical data from the Male Visible Human Project, the LSS model is constructed from the L1-S1 rigid vertebrae interconnected with hyperelastic fiber-reinforced FE intervertebral discs, ligaments, and facet joints. A mesh convergence study, sensitivity analyses, and systematic calibration were conducted with the hybrid functional spinal unit (FSU) L4/5. The predicted mechanical responses of the FSU L4/5, the lumbar spine (L1-L5), and the LSS were validated against literature data from in vivo and in vitro measurements and in silico models. Spinal mechanical responses considered when loaded with pure moments and combined loading modes were total and intervertebral range of motions, instantaneous axes and centers of rotation, facet joint contact forces, intradiscal pressures, disc bulges, and stiffnesses. Undesirable correlations with the FE mesh were minimized, the number of crisscrossed collagen fiber rings was reduced to five, and the individual influences of specific anatomical structures were adjusted to in vitro range of motions. Including intervertebral motion couplings for axial rotation and nonlinear stiffening under increasing axial compression, the predicted kinematic and structural mechanics responses were consistent with the comparative data. The results demonstrate that the hybrid simulation model is robust and efficient in reproducing valid mechanical responses to provide a starting point for upcoming optimizations and extensions, such as with active skeletal muscles.

Finite element analysis of load transition on sacroiliac joint during bipedal walking.

The sacroiliac joint (SIJ) is burdened with variant loads. However, no methods have allowed to measure objectively how the SIJ deforms during bipedal walking. In this study, in-vivo walking conditions were replicated in a kinematic model combining the finite element method with 3D walking analysis data divided into five phases in order to visualize the load transition on the SIJ and clarify the role of the SIJ. Both models with and without inclusion of the SIJ were investigated. In models with bilateral SIJs, the displacement differed greatly between the sacrum and both hip bones on the SIJ as the boundary. The movements of the sacrum involved a nutation movement in the stance phase and a counter-nutation in the swing phase relative to the ilium. In models without SIJs, the displacement of the pelvis and loads of pelvic ligaments decreased, and the equivalent stress of the SIJs increased compared to the model with SIJs. The walking loads cause distortion of the entire pelvis, and stress concentration at the SIJ are seen due to the morphology of the pelvic ring. However, the SIJs help dissipate the resulting stresses, and the surrounding ligaments are likewise involved in load transmission.

Pelvic floor activation upon stimulation of the sacral spinal nerves in sacral neuromodulation patients.

PURPOSE: To assess the activation of the different parts of the pelvic floor muscles (PFM) upon electrical stimulation of the sacral spinal nerves while comparing the different lead electrode configurations. MATERIAL AND METHODS: PFM electromyography (EMG) was recorded using an intravaginal multiple array probe with 12 electrodes pairs, which allows to make a distinction between the different sides and depths of the pelvic floor. In addition concentric needle EMG of the external anal sphincter was performed to exclude far-field recording. A medtronic InterStim tined lead (model 3889) was used as stimulation source. Standard SNM parameters (monophasic pulsed square wave, 210 microseconds, 14 Hz) were used to stimulate five different bipolar electrode configurations (3+0-/3+2-/3+1-/0+3-/1+3-) up to and around the sensory threshold. Of each EMG signal the stimulation intensity needed to evoke the EMG signals as well as its amplitude and latency were determined. Linear mixed models was used to analyse the data. RESULTS: Twenty female patients and 100 lead electrode configurations were stimulated around the sensory response threshold resulting in 722 stimulations and 12 times as many (8664) EMG recordings. A significant increase in EMG amplitude was seen upon increasing stimulation intensity (P < .0001). Large differences were noted between the EMG amplitude recorded at the different sides (ipsilateral>posterior>anterior>contralateral) and depths (deep>center>superficial) of the pelvic floor. These differences were noted for all lead electrodes configurations stimulated (P < .0001). Larger EMG amplitudes were measured when the active electrode was located near the entry point of the sacral spinal nerves through the sacral foramen (electrode #3). No differences in EMG latency could be withheld, most likely due to the sacral neuroanatomy (P > .05). CONCLUSIONS: A distinct activation pattern of the PFM could be identified for all stimulated lead electrode configurations. Electrical stimulation with the most proximal electrode (electrode #3) as the active one elicited the largest PFM contractions.

Effects of flexible sacrum positions during the second stage of labour on maternal and neonatal outcomes: A systematic review and meta-analysis.

AIMS AND OBJECTIVES: To assess the effects of flexible sacrum positions on mode of delivery, duration of the second stage of labour, perineal trauma, postpartum haemorrhage, maternal pain, abnormal foetal heart rate patterns and Apgar scores based on published literature. BACKGROUND: Maternal positions served as a nonmedical intervention may facilitate optimal maternal and neonatal outcomes during labour. Flexible sacrum positions are conducive to expanding pelvic outlet. Whether flexible sacrum positions have positive effects on maternal and neonatal well-being is a controversial issue under heated discussion. DESIGN: We performed a systematic review and meta-analysis based on PRISMA guidelines. METHODS: Randomised controlled trials (RCTs) comparing any flexible sacrum position with non-flexible sacrum position in the second stage of labour were included. PubMed, EMBASE, Cochrane Library, CINAHL, CNKI (China National Knowledge Infrastructure), SinoMed and Wanfang databases were searched from inception to 11 March 2019 for published RCTs. Risk of bias was assessed by the Cochrane criteria, and random-effects meta-analyses were conducted by RevMan 5.3. RESULTS: Sixteen studies (3,397 women) published in English were included. Flexible sacrum positions in the second stage of labour could reduce the incidence of operative delivery, instrumental vaginal delivery, caesarean section, episiotomy, severe perineal trauma, severe pain and shorten the duration of active pushing phase in the second stage of labour. However, flexible sacrum positions may increase the incidence of mild perineal trauma. There was no significant difference in the duration of the second stage of labour, maternal satisfaction and other outcomes. CONCLUSIONS: Flexible sacrum positions are superior in promoting maternal well-being during childbirth. However, several results require careful interpretation. More rigorous original studies are needed to further explore their effects. RELEVANCE TO CLINICAL PRACTICE: The results support the use of flexible sacrum positions. Flexible sacrum positions are recommended to apply flexibly or tailor to individual woman's labour progress.

Facet joint parameters which may act as risk factors for chronic low back pain.

BACKGROUND: Facet orientation (FO) and facet tropism (FT) are two important structural parameters of lumbar facet joint. The purpose of this study was to evaluate the association between facet joint parameters and chronic low back pain (LBP). METHODS: From June 2017 to January 2019, a total of 542 cases were enrolled in this study. There were 237 males and 305 females with a mean age of 35.8 years (range 18~59 years). All the cases were divided into a LBP group (LBP group) and a non-LBP group (N-LBP group) in this study. We compared their clinical parameters and facet joint parameters between two groups. RESULTS: The LBP group was composed of 190 male and 252 female, whose ages ranged from 17 to 59 years (35.6 ±7.9 y). The N- LBP group was composed of 47 male and 53 female, whose ages ranged from 18 to 59 years (35.9 ± 7.5 y). Of these parameters, BMI (P = 0.008) and FT (P = 0.003) at all three levels were found to be significantly associated with incidence of chronic LBP (P < 0.05), but FO were only found to be significant at L3-L4 level and L5-S1 level (P < 0.05). Logistic regression analysis showed that high BMI and large FT were significant risk factors for chronic LBP (P < 0.05), and FT were found to might be independent risk factors for chronic LBP. CONCLUSION: FT may play a more important role in the pathogenesis of chronic LBP.

High browsing skeletal adaptations in Spinophorosaurus reveal an evolutionary innovation in sauropod dinosaurs.

Sauropods were among the most diverse lineages of dinosaurs, with an ample geographic distribution throughout the Mesozoic. This evolutionary success is largely attributed to neck elongation and its impact on feeding efficiency. However, how neck elongation influenced exactly on feeding strategies is subject of debate. The process of mounting a nearly complete virtual skeleton of Spinophorosaurus nigerensis, from the Middle (?) Jurassic of Niger, has revealed several previously unknown osteological adaptations in this taxon. Wedged sacral and posterior dorsal vertebrae cause the presacral column to deflect antero-dorsally. This, together with elongated scapulae and humeri make the anterior region of the skeleton vertically lengthened. Also, elongated prezygapophyseal facets on the cervical vertebrae and a specialized first dorsal vertebra greatly increase the vertical range of motion of the neck. These characters support this early eusauropod as a more capable high browser than more basally branching sauropods. While limb proportions and zygapophyseal facets vary among Eusauropoda, the sacrum retained more than 10° of wedging in all Eusauropoda. This implied a functional constraint for sauropod species which evolved lower browsing feeding strategies: the antero-dorsal sloping caused by the sacrum had to be counteracted with further skeletal modifications, e.g. a ventrally curved mid to anterior presacral spine to hinder the dorsal slope of the whole presacral series caused by the wedged sacrum. This suggests that at least the last common ancestor of Eusauropoda developed high browsing capabilities, partially due to the modified wedged sacrum, likely a potential synapomorphy of the clade and key in the evolutionary history of the group.

The iliosacral joint in lizards: an osteological and histological analysis.

The development of the iliosacral joint (ISJ) in tetrapods represented a crucial step in the evolution of terrestrial locomotion. This structure is responsible for transferring forces between the vertebral column and appendicular skeleton, thus supporting the bodyweight on land. However, most research dealing with the water-to-land transition and biomechanical studies in general has focused exclusively on the articulation between the pelvic girdle and femur. Our knowledge about the contact between the pelvic girdle and vertebral column (i.e. the ISJ) at a tissue level is restricted so far to human anatomy, with little to no information available on other tetrapods. This lack of data limits our understanding of the development and evolution of such a key structure, and thus on the pattern and processes of the evolution of terrestrial locomotion. Therefore, we investigated the macro- and microanatomy of the ISJ in limb-bearing squamates that, similar to most non-mammalian, non-avian tetrapods, possess only two sacral ribs articulating with the posterior process of the ilium. Using a combination of osteology, micro-computed tomography and histology, we collected data on the ISJ apparatus of numerous specimens, sampling different taxa and different ontogenetic stages. Osteologically, we recorded consistent variability in all three processes of the ilium (preacetabular, supracetabular and posterior) and sacral ribs that correlate with posture and locomotion. The presence of a cavity between the ilium and sacral ribs, abundant articular cartilage and fibrocartilage, and a surrounding membrane of dense fibrous connective tissue allowed us to define this contact as a synovial joint. By comparison, the two sacral ribs are connected to each other mostly by dense fibrous tissue, with some cartilage found more distally along the margins of the two ribs, defining this joint as a combination of a syndesmosis and synchondrosis. Considering the intermediary position of the ISJ between the axial and appendicular skeletons, the shape of the articular surfaces of the sacral ribs and ilium, and the characteristics of the muscles associated with this structure, we argue that the mobility of the ISJ is primarily driven by the movements of the hindlimb during locomotion. We hypothesize that limited torsion of the ilium at the ISJ happens when the hip is abducted, and the joint is likely able to absorb the compressional and extensional forces related to the protraction and retraction of the femur. The mix of fibres and cartilage between the two sacral ribs instead serves primarily as a shock absorber, with the potential for limited vertical translation during locomotion.

Relative position of sacral base in the pelvis and its correlation with spino-pelvic parameters.

PURPOSE: To investigate the relationship between relative location of the sacral base and spinal alignment in standing healthy adult volunteers. METHODS: One hundred seventy-two volunteers (men = 83, mean age = 39.3 years [20-70], women = 89, mean age = 39.6 years [20-62]) with no history of spinal disease were imaged using a low-dose biplanar slot-scanning 3D X-ray imaging system. A circle was drawn around three points: cranial vertex of the iliac crest (A), caudal vertex of the ischium (B), and anterior vertex of the pubis. Pelvic height (PH) was defined as the diameter (A-B). A tangent line perpendicular to PH (C) was drawn by passing through (A). Sacral height (SH) was defined as the distance between (C) and the center of the sacral base parallel to PH. Relative SH (rSH) was calculated as SH/PH × 100. RESULTS: Mean (SD) rSH was 18.3 ± 3.2 (men 20.0 ± 2.9, women 16.7 ± 2.6). rSH significantly positively correlated with thoracic kyphosis (r = 0.20, p < 0.05), lumbar lordosis (r = 0.28, p < 0.05), pelvic incidence (r = 0.28, p < 0.05), and sacral slope (r = 0.32, p < 0.0001), and significantly negatively correlated with pelvic thickness (r = - 0.66, p < 0.0001). rSH did not correlate with pelvic tilt. CONCLUSION: The center of the sacral base is normally located 3.8 ± 0.8 cm caudal to the cranial vertex of the iliac crest. The sacral base was located more caudally in men than in women, regardless of age. The more caudal the sacral base, the angle of the spino-pelvic parameters (TK, LL, PI, SS) progressively increases along with a decrease in the sacro-acetabular distance (Pth). Pelvic tilt did not correlate with the location of the sacrum.

Motion-based prediction of external forces and moments and back loading during manual material handling tasks.

This paper evaluates a method for motion-based prediction of external forces and moments on manual material handling (MMH) tasks. From a set of hypothesized contact points between the subject and the environment (ground and load), external forces were calculated as the minimal forces at each contact point while ensuring the dynamics equilibrium. Ground reaction forces and moments (GRF&M) and load contact forces and moments (LCF&M) were computed from motion data alone. With an inverse dynamics method, the predicted data were then used to compute kinetic variables such as back loading. On a cohort of 65 subjects performing MMH tasks, the mean correlation coefficients between predicted and experimentally measured GRF for the vertical, antero-posterior and medio-lateral components were 0.91 (0.08), 0.95 (0.03) and 0.94 (0.08), respectively. The associated RMSE were 0.51 N/kg, 0.22 N/kg and 0.19 N/kg. The correlation coefficient between L5/S1 joint moments computed from predicted and measured data was 0.95 with a RMSE of 14 Nm for the flexion/extension component. In conclusion, this method allows the assessment of MMH tasks without force platforms, which increases the ecological aspect of the tasks studied and enables performance of dynamic analyses in real settings outside the laboratory.

Serotonergic modulation of sacral dorsal root stimulation-induced locomotor output in newborn rat.

Descending neuromodulators from the brainstem play a major role in the development and regulation of spinal sensorimotor functions. Here, the contribution of serotonergic signaling in the lumbar spinal cord was investigated in the context of the generation of locomotor activity. Experiments were performed on in vitro spinal cord preparations from newborn rats (0-5 days). Rhythmic locomotor episodes (fictive locomotion) triggered by tonic electrical stimulations (2Hz, 30s) of a single sacral dorsal root were recorded from bilateral flexor-dominated (L2) and extensor-dominated (L5) ventral roots. We found that the activity pattern induced by sacral stimulation evolves over the 5 post-natal (P) day period. Although alternating rhythmic flexor-like motor bursts were expressed at all ages, the locomotor pattern of extensor-like bursting was progressively lost from P1 to P5. At later stages, serotonin (5-HT) and quipazine (5-HT2A receptor agonist) at concentrations sub-threshold for direct locomotor network activation promoted sacral stimulation-induced fictive locomotion. The 5-HT2A receptor antagonist ketanserin could reverse the agonist's action but was ineffective when fictive locomotion was already expressed in the absence of 5-HT (mainly before P2). Although inhibiting 5-HT7 receptors with SB266990 did not affect locomotor pattern organization, activating 5-HT1A receptors with 8-OH-DPAT specifically deteriorated extensor phase motor burst activity. We conclude that during the first 5 post-natal days in rat, serotonergic signaling in the lumbar cord becomes increasingly critical for the expression of fictive locomotion. Our findings therefore further underline the importance of both descending serotonergic and sensory afferent pathways in shaping locomotor activity during postnatal development. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

A prospective longitudinal comparison of the sacral inclination angle in women between their early and advanced pregnancy and 6-month postpartum follow-up.

PURPOSE: The impact of pregnancy on the anterior-posterior sacral orientation and its relation to lumbopelvic pain and weight gain has not been fully recognized. This longitudinal study aimed to compare the sacral inclination angle in women between their early and advanced pregnancy and at 6 months postpartum. The authors also searched for a correlation between the sacral inclination and lumbopelvic pain, BMI and change in body mass. METHODS: Thirteen healthy women participated in the study. Data were collected at 8-16 and 35-38 weeks of gestation, and at 27-31.5 postpartum weeks. At each session, the women's sacral inclination angles were measured using the Saunders digital inclinometer. Data were also collected on lumbopelvic pain, BMI and body mass gain/loss. RESULTS: There was no effect of the evaluation period on the sacral inclination (p > 0.05); however, various individual values of the sacral inclination in pregnancy and postpartum were noted. In advanced pregnancy, 61.5% of the women had recurrent pain in the lumbopelvic region. The sacral inclination did not correlate with the lumbopelvic pain, BMI and body mass change (p > 0.05) in the pregnancy and postpartum periods. CONCLUSIONS: Advanced pregnancy did not influence sacral inclination. However, individuals varied in their responses. Therefore, we suggest that an individually-based physical therapy approach concerning proper posture during and after pregnancy should be emphasized. The sacral inclination had no impact on the occurrence of recurrent lumbopelvic pain. BMI and changes in body mass did not influence the sacral inclination in advanced pregnancy and at 6 months postpartum.

Effect of maternal birth positions on duration of second stage of labor: systematic review and meta-analysis.

BACKGROUND: It is believed that giving birth in an upright position is beneficial for both mother and the infant for several physiologic reasons. An upright positioning helps the uterus to contract more strongly and efficiently, the baby gets in a better position and thus can pass through the pelvis faster. Upright and lateral positions enables flexibility in the pelvis and facilitates the extension of the outlet. Before implementing a change in birthing positions in our clinics we need to review evidences available and context valid related to duration of second stage of labor and birthing positions. Therefore this review aimed to examine the effect of maternal flexible sacrum birth position on duration of second stage of labor. METHOD: The research searched articles using bibliographical Databases: Medline/PUBMED, SCOPUS, Google scholar and Google. All study designs were considered while investigating the impact of maternal flexible sacrum birthing positioning in relation duration of second stage of labor. Studies including laboring mothers with normal labor and delivery. A total of 1985 women were included in the reviewed studies. We included both qualitative and quantitative analysis. RESULTS: We identified 1680 potential citations, of which 8 articles assessed the effect of maternal upright birth positioning on the reduction during the duration of second stage of labor. Two studies were excluded because of incomplete reports for meta analysis. The result suggested a reduction in duration of second stage of labor among women in a flexible sacrum birthing position, with a mean duration from 3.2-34.8. The pooled weighted mean difference with random effect model was 21.118(CI: 11.839-30.396) minutes, with the same significant heterogeneity between the studies (I2 = 96.8%, p < 000). CONCLUSION: The second stage duration was reduced in cases of a flexible sacrum birthing position. Even though the reduction in duration varies across studies with considerable heterogeneity, laboring women should be encouraged to choose her comfortable birth position. Researchers who aim to compare different birthing positions should consider study designs which enable women to choose birthing position. PROSPERO REGISTRATION NUMBER: [CRD42019120618].

Assessing the ability of the Sacral Autonomic Standards to document bladder and bowel function based upon the Asia Impairment Scale.

Study design: Retrospective review of data. Objective: To determine if there is a relationship between the Asia Impairment Scale (AIS) and the bladder and bowel components of the International Standards to Document Remaining Autonomic Function after SCI (ISAFSCI). Setting: University-Based Academic Rehabilitation Program. Methods: Retrospective cross-sectional study assessing International Standards for Neurologic Classification After SCI (ISNCSCI) examination along with bladder and bowel components of the ISAFSCI. Results: Subjects with AIS A injuries were statistically less likely to have history of bladder control and bowel control per investigator determination and bladder sensation via self-report versus patients categorized with AIS B injuries. Self-reported history of bowel sensation and control of voiding were more likely in subjects with C, D, or E injuries than with B injuries. Bowel and bladder control as determined by investigator and bladder and bowel sensation and control as self-reported were all statistically less likely in persons with AIS A injuries versus CDE. Conclusions: This retrospective study provides initial data regarding components of the bladder and bowel sections of the sacral ISAFSCI and AIS. Further prospective research is needed to further characterize the relationship between retention of bladder and bowel sensation and function and the AIS. We suggest that incorporation of the sacral components of the ISAFSCI into the ISNCSCI may be beneficial to obtain further information about retention of sacral function with specific patterns of injury.

Coronal and sagittal spinal alignment in lumbar disc herniation with scoliosis and trunk shift.

BACKGROUND: To investigate the incidence of scoliosis and trunk shift in patients with LDH (lumbar disc herniation) and analyze the differences in spinopelvic alignment among patients with or without trunk shift and non-symptom controls. MATERIALS AND METHODS: All included subjects had standard upright antero-posterior and lateral radiographs of the whole spine taken. Evidence of disc herniation was confirmed by computed tomography or magnetic resonance imaging. The parameters measured included trunk shift and Cobb angle, TK (thoracic kyphosis), TLK (thoraco-lumbar junction kyphosis), LL (lumbar lordosis), PI (pelvic incidence), SS (sacral slope), PT (pelvic tilt) and SVA (sagittal vertical axis). RESULTS: Sixty-eight patients with LDH and 61 controls were included. There were significantly more male patients with trunk shift than the patients without trunk shift. Forty-two patients had curve magnitudes ranging from 5 to 38°. The trunk shift ranged from 0.5 to 7.3 cm. A total of 54.76% of patients had a disc herniation on the concave side of the main curve. Fifty percent of patients showed a trunk shift towards the opposite side of disc herniation. There were significant differences in spinopelvic parameters among groups. Significant correlations were also observed between several spinopelvic parameters in the three groups. However, the degrees of correlations among the spinopelvic parameters differed among the three groups. CONCLUSION: Spinal sagittal morphology in LDH patients with trunk shift exhibits a more anterior shift of the C7 plumb line, less LL, and a more horizontal sacrum. Correlation analysis indicated a disharmonious spinopelvic interaction and a change in the compensatory model in patients with LDH.

Physiological variations in the sagittal spine alignment in an asymptomatic elderly population.

BACKGROUND CONTEXT: Sagittal plane alignment is of crucial importance for the treatment of spinal deformities. When planning corrective strategies, spine surgeons need to refer to normative parameters' ranges which characterize the alignment in the asymptomatic population. Changes are known to occur with age. For the Caucasian population, the reference ranges are extensively documented for the young and middle-aged adults. In contrast, only a few studies have evaluated individuals in advanced age (>60 years) and in groups of limited numbers of subjects (less than 50). PURPOSE: To describe the normative parameter ranges of sagittal spine alignment in a large population of asymptomatic elderly subjects. STUDY DESIGN/SETTING: Monocentric, prospective, cross-sectional study. PATIENT SAMPLE: One hundred sixty asymptomatic elderly volunteers (age>60 years, Caucasian heritage), consecutively enrolled. OUTCOME MEASURES: Sagittal parameters of spine and pelvis: thoracic kyphosis (TK); lumbar lordosis (LL); sacral slope (SS); pelvic incidence (PI); pelvic tilt (PT); sagittal vertical axis (SVA); T1 pelvic angle (TPA); mismatch between PI and LL (PI-LL); Roussouly classification of the lumbopelvic profile. METHODS: Each subject underwent one radiographic scan, performed in standing position with EOS low-dose system (EOS Imaging, Paris, France). The radiographic images were processed with sterEOS software allowing identification of the anatomical parameters and the presence of scoliosis. SVA, TPA, and the lumbopelvic profile were manually measured in the lateral images. The results were compared to previous studies describing younger adult populations. The study was supported by the Italian Ministry of Health in the amount of $15,000. The authors declare that there are no conflicts of interests. RESULTS: Overall, the average values of the spinopelvic parameters were the followings: TK, 55±14°; LL, 57±12°; PI, 55±11°; SS, 38±10°; PT, 16±7°. The average PI-LL, SVA, and TPA was -3±11°, 25±32 mm, and 14.6±7.4°, respectively. TK, TPA, and SVA were found increasing with age. As for classification of the lumbopelvic profile, 16% of subjects were excluded because they were considered not to belong to any of the Roussouly types. In the classified subjects, the distribution was similar to that of younger adults. Asymptomatic scoliosis (average Cobb angle, 22±7°) was identified in 27% of individuals. CONCLUSIONS: The ranges of values pointed out differences compared to younger adults and represent an important resource for spine surgeons in planning the surgical correction of spinal deformities. The characteristic changes occurring with age, as well as the observed presence of mild or moderate asymptomatic scoliosis, should be carefully taken into account. The classification of the lumbopelvic profile based on the Roussouly scheme revealed some limitations, although similar frequencies were identified compared to younger adults.

A patient specific computational biomechanical model for the entire lumbosacral spinal unit with imposed spondylolysis.

BACKGROUND: A biomechanical model of the lumbosacral spinal unit between L1-S1 was developed to investigate the behavior of normal and select pathological states. Our aims were to generate predictive structural models for mechanical deformation including critical stresses in the spine components and to investigate the probability of subsequent lumbar spine fractures in the presence of unilateral spondylolysis. METHODS: A non-linear three-dimensional finite element pathology-free model of the L1-S1 lumbosacral unit was generated using patient-specific computerized tomography scans and calibrated by comparing it to experimental data of a range of motion modes consisting of flexion, extension, left and right lateral bending, and left and right axial rotation. Unilateral and bilateral pars defects were created on the isthmus of L5 to simulate spondylolysis. FINDINGS: Results showed that under flexion, left lateral bending and right axial rotation, stresses were higher on the contralateral L5 pars-interarticularis, whereas, no significant changes occurred on the left-right isthmus of the L2-L4 and S1. Significant changes in the range of motion compared to the pathology-free model were observed in bilateral spondylolysis not only adjacent to the pars defect area but also in other lumbar spine levels. INTERPRETATION: The proposed pathology-free lumbosacral unit model showed good correlation with experimental tests for all loading cases. In unilateral spondylolysis, a subsequent pars defect was observed within the same vertebra. The overall modeling approach can be used to study different pathological states.

Needle Placement and Position of Electrical Stimulation Inside Sacral Foramen Determines Pelvic Floor Electromyographic Response-Implications for Sacral Neuromodulation.

BACKGROUND: Lead placement within the sacral foramen in sacral neuromodulation patients is guided by visual assessment of the contraction of the pelvic floor musculature (PFM) and/or verbal assessment of the sensation and location of sensation upon stimulation. Generally, lead placement is proceeded by needle probing. This study evaluates which location inside a single sacral foramen would be most ideal for the release of the permanent electrode lead, by measuring electromyographic (EMG) motor responses of the PFM upon stimulation of a peripheral nerve evaluation (PNE) needle. MATERIALS AND METHODS: In eight patients, four standard PNE needles, and in one patient, two PNE needles, were introduced into the same foramen, parallel to the midline and parallel to each other. Position was verified by X-ray. Needles were stimulated (square pulsed waves, 210 µsec, 14 Hz) at increasing amplitudes (1-2-3-5-7-10 mA). PFM EMG was measured using the Multiple Array Probe (MAPLe) placed intravaginally or intrarectally, with 24 derivations. For this study, the mean (normalized) EMG was taken of all electrodes and different positions within the foramen were compared using the Wilcoxon signed rank test. RESULTS: A total of 202 PFM EMG measurements were recorded upon stimulation. EMG motor responses of the PFM for current stimulation = <2 mA showed statistically significant higher mean (normalized) EMG values for needles positioned cranial, medial, and cranial-medial, in comparison to needles positioned caudal, lateral, and caudal-lateral (p = 0.004; p = 0.021; p = 0.002). CONCLUSIONS: Our data suggest stronger PFM contractions are elicit in cranial- and medial-placed PNE needles upon stimulation with clinically relevant current amplitudes (≤ 2 mA). Placement of the lead should aim for this spot in the foramen.