Lumbosacral Cerebrospinal Fluid Volume in Humans Using Three-Dimensional Magnetic Resonance Imaging

Preoperative echocardiography as a predictor of spinal anesthesia-induced hypotension in older patients with mild left ventricular diastolic dysfunction: a retrospective observational study

BACKGROUND

Spinal anesthesia-induced hypotension (SAH) frequently occurs in older patients, many of whom have mild left ventricular (LV) diastolic dysfunction, often asymptomatic at rest. This study investigated the association between preoperative echocardiographic measurements and SAH in older patients with mild LV diastolic dysfunction.

METHODS

We conducted a retrospective observational study using data from electronic medical records. The patients ≥ 65 years old who underwent spinal anesthesia for urologic surgery between January 2016 and December 2017 and whose preoperative echocardiography within 6 months before surgery revealed grade I LV diastolic dysfunction were recruited. SAH was investigated using the anesthesia records. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed.

RESULTS

A total of 163 patients were analyzed. SAH and significant SAH developed in 55 (33.7%) patients. The mitral inflow E velocity was an independent risk factor for SAH (odds ratio [OR], 0.886; 95% confidence interval [CI], 0.845-0.929; P < 0.001). The area under the ROC curve for mitral inflow E velocity to predict SAH was 0.819 (95% CI, 0.752-0.875; P < 0.001). If mitral inflow E velocity was ≤ 60 cm/s, SAH was predicted with a sensitivity of 83.6% and specificity of 70.4%.

CONCLUSIONS

The preoperative mitral inflow E velocity demonstrated the greatest predictability of SAH in older patients with mild LV diastolic dysfunction. This may assist in identifying patients at high risk of SAH and guiding preventive strategies in the future.

Effective Dose Range of Intrathecal Isobaric Bupivacaine to Achieve T5–T10 Sensory Block Heights for Elderly and Overweight Patients: An Observational Study

Background and Objectives: The dose selection for isobaric bupivacaine determines the success of spinal anesthesia (SA). A dose higher than the optimal dose causes high SA, whereas an underdose leads to inadequate spread of cephalad. As it involves anatomical and physiological alterations, the dosing should be reduced with advancing age and body mass index values. Therefore, this study aimed to demonstrate the association between the isobaric bupivacaine dose and block height, and to determine the dose intervals of bupivacaine to achieve the T5–T10 sensory block with a low probability of high SA in elderly and overweight patients. Material and Methods: This retrospective observational study recruited 1079 adult patients who underwent SA with 0.5% isobaric bupivacaine from 2018 to 2021. The patients were divided into four categories: category 1 (age < 60, BMI < 25), category 2 (age < 60, BMI ≥ 25), category 3 (age ≥ 60, BMI < 25), and category 4 (age ≥ 60, BMI ≥ 25). The bupivacaine dose and sensory block height (classified into three levels: high (T1–T4), favorable (T5–T10), and low (T11–L2)) were recorded. Results: The sensory block level increased significantly with increasing doses of bupivacaine for patients in categories 1 and 2. The suggested dose ranges for the favorable block heights were 15–17 and 10.5–16 mg in patient categories 1–2 and 3–4, respectively. In these dose ranges, the probability range of high SA was 10–15%. Conclusions: The sensory block height following SA was associated with the bupivacaine dose in patients aged <60 years. Regardless of the BMI, the suggested dose ranges of 0.5% isobaric bupivacaine are 15–17 mg (3.0–3.4 mL) and 10.5–16 mg (2.1–3.2 mL) for patients aged <60 and ≥60 years, respectively.

Quantitative Measurement of Spinal Cerebrospinal Fluid by Cascade Artificial Intelligence Models in Patients with Spontaneous Intracranial Hypotension

Cerebrospinal fluid (CSF) hypovolemia is the core of spontaneous intracranial hypotension (SIH). More than 1000 magnetic resonance myelography (MRM) images are required to evaluate each subject. An effective spinal CSF quantification method is needed. In this study, we proposed a cascade artificial intelligence (AI) model to automatically segment spinal CSF. From January 2014 to December 2019, patients with SIH and 12 healthy volunteers (HVs) were recruited. We evaluated the performance of AI models which combined object detection (YOLO v3) and semantic segmentation (U-net or U-net++). The network of performance was evaluated using intersection over union (IoU). The best AI model was used to quantify spinal CSF in patients. We obtained 25,603 slices of MRM images from 13 patients and 12 HVs. We divided the images into training, validation, and test datasets with a ratio of 4:1:5. The IoU of Cascade YOLO v3 plus U-net++ (0.9374) was the highest. Applying YOLO v3 plus U-net++ to another 13 SIH patients showed a significant decrease in the volume of spinal CSF measured (59.32 ± 10.94 mL) at disease onset compared to during their recovery stage (70.61 ± 15.31 mL). The cascade AI model provided a satisfactory performance with regard to the fully automatic segmentation of spinal CSF from MRM images. The spinal CSF volume obtained through its measurements could reflect a patient’s clinical status.

Total failure of spinal anesthesia for cesarean delivery, associated factors, and outcomes: A retrospective case-control study

Spinal anesthesia is the anesthetic technique of choice for patients undergoing cesarean delivery. In the present study, total spinal anesthesia failure was defined as a case when an absent blockade or inadequate surgery required general anesthesia administration with an endotracheal tube. This study aimed to investigate factors related to this condition and report its maternal and neonatal outcomes. This retrospective matched case-control study was conducted by recruiting 110 patients with failed spinal anesthesia and 330 control patients from September 1, 2016, to April 30, 2020, in the largest university hospital, Thailand. Of 12,914 cesarean deliveries, 12,001 patients received single-shot spinal anesthesia (92.9%) during the study period. Total spinal anesthesia failure was experienced by 110/12,001 patients, giving an incidence of 0.9%. Factors related to the failures were a patient body mass index (BMI) ≤29.5 kg/m2 (adjusted odds ratio 1.9; 95% confidence interval 1.2-3.1; P = .010) and a third-year resident (the most senior trainee) performing the spinal block (adjusted odds ratio 2.4; 95% confidence interval 1.5-3.7; P < .001). In the group with failed spinal anesthesia, neonatal Apgar scores at 1 and 5 minutes were lower than those of the control group (both P < .001). Two patients in the failed spinal anesthesia group (2/110; 1.8%) had difficult airways and desaturation. Independent factors associated with total spinal anesthesia failure were a BMI of ≤29.5 kg/m2 and a third-year resident performing the spinal block. Although the incidence of total failure was infrequent, there were negative consequences for the mothers and neonates. Adjusting the dose of bupivacaine according to the weight and height of a patient is recommended, with a higher dose appropriate for patients with a lower BMI.

Intrathecal Drug Delivery: Advances and Applications in the Management of Chronic Pain Patient

Advances in our understanding of the biology of spinal systems in organizing and defining the content of exteroceptive information upon which higher centers define the state of the organism and its role in the regulation of somatic and automatic output, defining the motor response of the organism, along with the unique biology and spatial organization of this space, have resulted in an increased focus on therapeutics targeted at this extracranial neuraxial space. Intrathecal (IT) drug delivery systems (IDDS) are well-established as an effective therapeutic approach to patients with chronic non-malignant or malignant pain and as a tool for management of patients with severe spasticity and to deliver therapeutics that address a myriad of spinal pathologies. The risk to benefit ratio of IDD makes it a useful interventional approach. While not without risks, this approach has a significant therapeutic safety margin when employed using drugs with a validated safety profile and by skilled practioners. The present review addresses current advances in our understanding of the biology and dynamics of the intrathecal space, therapeutic platforms, novel therapeutics, delivery technology, issues of safety and rational implementation of its therapy, with a particular emphasis upon the management of pain.

Morphometrics of the Spinal Cord and Surrounding Structures in Alligator mississippiensis

Simple Summary

Morphometric analysis of the spinal cord and surrounding tissue of the American alligator (Alligator mississippiensis) reveals that there are four significantly discrete regions; cervical, thoracic, lumbar, and caudal. Crocodylians, unlike mammals, have a caudal spinal cord that extends throughout the length of their tail (which accounts for roughly 50% of their total body length). Alligator mississippiensis has one of the largest ranges of body sizes among terrestrial vertebrates, this study documents how the different spinal structures change with increasing body size. Though most of the structures exhibit slightly positive allometry, a few exhibit slightly negative allometry; these differences mean that there are significant relational changes as hatchlings grow into large adults. This study provides the first documentation that A. mississippiensis has an expansive subdural space, a lumbar cistern, at the pelvis.

Abstract

Understanding the fluid dynamics of the cerebrospinal fluid requires a quantitative description of the spaces in which it flows, including the spinal cord and surrounding meninges. The morphometrics of the spinal cord and surrounding tissues were studied in specimens of the American alligator (Alligator mississippiensis) ranging from hatchlings through adults. Within any size class of alligators (i.e., hatchlings), along the axial length there are significant differences in the size of the spinal cord, meninges, and vertebral canal; these differences can be used to define discrete cervical, thoracic, lumbar and caudal regions. When compared across the range of body sizes in Alligator, every structure in each spinal region had a distinctive growth rate; thus, the physical arrangements between the structures changed as the alligator grew. The combination of regional differentiation and differential growth rates was particularly apparent in the lumbar meninges where a unique form of lumbar cistern could be identified and shown to decrease in relative size as the alligator ages. This analysis of the spinal cord and surrounding tissues was undertaken to develop a data set that could be used for computational flow dynamics of the crocodilian cerebrospinal fluid, and also to assist in the analysis of fossil archosaurs.

Correlation of the lumbar dural sac dimension with the spread of spinal anesthesia in elderly female patients: A prospective observational study

BACKGROUND

To test a hypothesis that the dural sac dimension would be correlated with the spinal block level, we evaluated the correlation between the lumbar dural sac dimension and the spread of spinal anesthesia in elderly women.

METHODS

In 40 women over the age of 65 years, the lumbar dural sac dimensions were measured at the L2-L3, L3-L4, L4-L5, and L5-S1 intervertebral spaces using ultrasonography in the lateral decubitus position, followed by the administration of spinal anesthesia. The correlation coefficients were analyzed for the lumbar dural sac dimension at each intervertebral level, peak sensory block level, peak motor block, time to peak sensory and peak motor blockade, durations of sensory and motor blockade, and patient characteristics. We subsequently analyzed the partial correlations between the lumbar dural sac dimension and the outcomes of spinal anesthesia, while adjusting for age, body mass index, and waist circumference.

RESULTS

Peak sensory block level was inversely correlated with each lumbar sac dimension: L2-L3 (ρ = -0.37, P = .029), L3-L4 (ρ = -0.57, P < .001), L4-L5 (ρ = -0.65, P < .001), and L5-S1 (ρ = -0.49, P = .002) intervertebral spaces. Partial correlation analysis with adjustment for age, body mass index, and waist circumference revealed inverse correlations between the lumbar dural sac dimension at the following intervertebral spaces and peak sensory block level: L3-L4 (r = -.52, P = .003), L4-L5 (r = -.76, P < .001), and L5-S1 (r = -.65, P < .001).

CONCLUSIONS

Outcomes of ultrasonographic investigation revealed an inverse correlation between the lumbar dural sac dimension and peak sensory block level in elderly women.

Microanatomy Relevant to Intrathecal Drug Delivery

This chapter describes the microanatomy of the spinal cord that is relevant to intrathecal drug delivery started with covering of the spinal cord that are pierced to enter the intrathecal space. The dural sac is mostly constituted by the outer layer of dura and the inner layer called arachnoid membrane, which regulates diffusion of drugs into the intrathecal space. The pia matter surrounding the spinal cord is a permeable structure allowing the passage of drugs through intercellular spaces. The relationship between nerve roots, CSF, and subarachnoid catheters determines the passage of an intrathecal catheter which can cause damage to nerve roots and spinal cord. Multiple factors may be involved in the mechanisms of drug diffusion across the membranes of the spinal cord, as well as in their dilution with the CSF, which will lead to the final drug distribution and availability at nerve roots and the spinal cord.

Population pharmacokinetics of oxycodone in plasma and cerebrospinal fluid after epidural and intravenous administration

Objectives: To establish the first plasma and cerebrospinal fluid (CSF) oxycodone population pharmacokinetic (PopPK) model after epidural (EPI) and intravenous (IV) oxycodone administration. Methods: The study was conducted with 30 female subjects undergoing elective gynecological surgery with epidural analgesia. A parallel single dose of EPI oxycodone with IV placebo (EPI group; n = 18) or IV oxycodone with EPI placebo (IV group; n = 12) was administered. An epidural catheter for drug administration was placed at T12/L1 and a spinal catheter for CSF sampling at L3/4. Plasma and CSF for oxycodone analysis were frequently collected. A PopPK model was built using the NONMEM software package. Results: Plasma and CSF oxycodone concentrations were evaluated using separate central plasma and CSF compartments and separate peripheral plasma and CSF compartments. Epidural space served as a depot compartment with transfer to both the plasma and CSF central compartments. The population parameters for plasma clearance and apparent distribution volumes for central and peripheral compartments for plasma and CSF were 37.4 L/h, 90.2 L, 68.9 L, 0.035 L (fixed based on literature), and 0.039 L, respectively. Conclusion: A PopPK model was developed and found to precisely and accurately describe oxycodone time-concentration data in plasma and CSF.

Intrathecal Morphine Following Lumbar Fusion: A Randomized, Placebo-Controlled Trial

BACKGROUND

Despite the potential for faster postoperative recovery and the ease of direct intraoperative injection, intrathecal morphine is rarely provided in lumbar spine surgery.

OBJECTIVE

To evaluate the safety and efficacy of intrathecal morphine following lumbar fusion.

METHODS

We randomly assigned 150 patients undergoing elective instrumented lumbar fusion to receive a single intrathecal injection of morphine (0.2 mg) or placebo (normal saline) immediately prior to wound closure. The primary outcome was pain on the visual-analogue scale during the first 24 h after surgery. Secondary outcomes included respiratory depression, treatment-related side effects, postoperative opioid requirements, and length of hospital stay. An intention-to-treat, repeated-measures analysis was used to estimate outcomes according to treatment in the primary analysis.

RESULTS

The baseline characteristics of the 2 groups were similar. Intrathecal morphine reduced pain both at rest (32% area under the curves [AUCs] difference, P < .01) and with movement (22% AUCs difference, P < .02) during the initial 24 h after surgery. The risk of respiratory depression was not increased by intrathecal morphine (hazard ratio, 0.86; 95% confidence interval, 0.44 to 1.68; P = .66). Although postoperative opioid requirements were reduced with intrathecal morphine (P < .03), lengths of hospital stay were similar (P = .32). Other than a trend towards increased intermittent catheterization among patients assigned to intrathecal morphine (P = .09), treatment-related side effects did not significantly differ. The early benefits of intrathecal morphine on postoperative pain were no longer apparent after 48 h.

CONCLUSION

A single intrathecal injection of 0.2 mg of morphine safely reduces postoperative pain following lumbar fusion.

Abdominal girth and dorso-sacral distance can be used to estimate lumbosacral cerebral fluid volume

BACKGROUND

Patients' abdominal girth and vertebral column length are highly correlated with the spread of local anaesthetics after spinal anaesthesia. Lumbosacral cerebrospinal fluid volume is the primary determinant for spinal spread. Thus, we attempted to verify the hypothesis that abdominal girth and dorso-sacral distance are correlated with lumbosacral cerebrospinal fluid volume.

METHODS

Forty-five healthy volunteers were enrolled in this study to measure lumbosacral cerebrospinal fluid volume using magnetic resonance imaging. The age, height, weight, abdominal girth, dorso-sacral distance and lumbosacral cerebrospinal fluid volume of the volunteers were recorded. Multiple linear regression analysis was used to analyse the correlation between age, height, weight, abdominal girth, dorso-sacral distance and lumbosacral cerebrospinal fluid volume.

RESULTS

Two volunteers were excluded because of lumbar disc herniation, leaving 43 volunteers for analysis. Multiple linear regression analysis showed a strong correlation between abdominal girth, dorso-sacral distance and lumbosacral cerebrospinal fluid volume (both P < 0.01). The adjusted R² was 0.644. Volunteers with small abdominal girth showed clear images of cerebrospinal fluid in the nerve root cuff at the intervertebral foramen in the three-dimensional magnetic resonance imaging reconstruction of lumbosacral cerebrospinal fluid, while the images were vague in volunteers with large abdominal girth. Clearer images implied larger lumbosacral cerebrospinal fluid volume, while vaguer images, smaller lumbosacral cerebrospinal fluid volume.

CONCLUSIONS

Multiple regression analysis revealed that abdominal girth and dorso-sacral distance were correlated with lumbosacral cerebrospinal fluid volume. Smaller abdominal girths and larger dorso-sacral distances predict larger lumbosacral cerebrospinal fluid volume.

A 3D subject-specific model of the spinal subarachnoid space with anatomically realistic ventral and dorsal spinal cord nerve rootlets

BACKGROUND

The spinal subarachnoid space (SSS) has a complex 3D fluid-filled geometry with multiple levels of anatomic complexity, the most salient features being the spinal cord and dorsal and ventral nerve rootlets. An accurate anthropomorphic representation of these features is needed for development of in vitro and numerical models of cerebrospinal fluid (CSF) dynamics that can be used to inform and optimize CSF-based therapeutics.

METHODS

A subject-specific 3D model of the SSS was constructed based on high-resolution anatomic MRI. An expert operator completed manual segmentation of the CSF space with detailed consideration of the anatomy. 31 pairs of semi-idealized dorsal and ventral nerve rootlets (NR) were added to the model based on anatomic reference to the magnetic resonance (MR) imaging and cadaveric measurements in the literature. Key design criteria for each NR pair included the radicular line, descending angle, number of NR, attachment location along the spinal cord and exit through the dura mater. Model simplification and smoothing was performed to produce a final model with minimum vertices while maintaining minimum error between the original segmentation and final design. Final model geometry and hydrodynamics were characterized in terms of axial distribution of Reynolds number, Womersley number, hydraulic diameter, cross-sectional area and perimeter.

RESULTS

The final model had a total of 139,901 vertices with a total CSF volume within the SSS of 97.3 cm³. Volume of the dura mater, spinal cord and NR was 123.1, 19.9 and 5.8 cm³. Surface area of these features was 318.52, 112.2 and 232.1 cm² respectively. Maximum Reynolds number was 174.9 and average Womersley number was 9.6, likely indicating presence of a laminar inertia-dominated oscillatory CSF flow field.

CONCLUSIONS

This study details an anatomically realistic anthropomorphic 3D model of the SSS based on high-resolution MR imaging of a healthy human adult female. The model is provided for re-use under the Creative Commons Attribution-ShareAlike 4.0 International license (CC BY-SA 4.0) and can be used as a tool for development of in vitro and numerical models of CSF dynamics for design and optimization of intrathecal therapeutics.

Quantitative Measurement of CSF in Patients with Spontaneous Intracranial Hypotension

BACKGROUND AND PURPOSE

CSF hypovolemia is a core feature of spontaneous intracranial hypotension. Spontaneous intracranial hypotension is characterized by orthostatic headache and radiologic manifestations, including CSF along the neural sleeves, diffuse pachymeningeal enhancement, and/or venous engorgement. However, these characteristics are only qualitative. Quantifying intraspinal CSF volumes could improve spontaneous intracranial hypotension diagnosis and evaluation of hypovolemic statuses in patients with spontaneous intracranial hypotension. The purpose of this study was to compare intraspinal CSF volumes across spontaneous intracranial hypotension stages and to test the clinical applicability of these measures.

MATERIALS AND METHODS

A cohort of 23 patients with spontaneous intracranial hypotension and 32 healthy controls was subjected to brain MR imaging and MR myelography with 1.5T imaging. An automatic threshold-based segmentation method was used to calculate intraspinal CSF volumes at initial hospitalization (spontaneous intracranial hypotension-initial), partial improvement (spontaneous intracranial hypotension-intermediate), and complete recovery (spontaneous intracranial hypotension-recovery) stages.

RESULTS

The mean intraspinal CSF volumes observed were the following: 95.31 mL for healthy controls, 72.31 mL for spontaneous intracranial hypotension-initial, 81.15 mL for spontaneous intracranial hypotension-intermediate, and 93.74 mL for spontaneous intracranial hypotension-recovery. Increased intraspinal CSF volumes were related to disease recovery (P < .001). The intraspinal CSF volumes of patients before complete recovery were significantly lower than those of healthy controls. With the estimated intradural CSF volumes as a reference, the intraspinal CSF volume percentage was lower in patients with spontaneous intracranial hypotension with venous engorgement than in those without it (P = .058).

CONCLUSIONS

With a threshold-based segmentation method, we found that spinal CSF hypovolemia is fundamentally related to spontaneous intracranial hypotension. Intraspinal CSF volumes could be a sensitive parameter for the evaluation of treatment response and follow-up monitoring in patients with spontaneous intracranial hypotension.

Levobupivacaine for Spinal Anesthesia in Children: Cerebrospinal Fluid Aspiration Before the Injection Does not Affect the Spread or Duration of the Sensory Block

Background

Several factors are thought to affect the spread and duration of spinal anesthesia (SA) in adults. These include the volume of cerebrospinal fluid (CSF) in the lumbar spinal canal, which has a negative correlation with both the spread and duration of the sensory block.

Objectives

We evaluated whether CSF aspiration before an injection of levobupivacaine affected the spread or duration of SA in children.

Patients and Methods

SA was induced by levobupivacaine (5 mg/mL, 0.25 - 0.5 mg/kg) in 186 children aged 10 months to 18 years (mean of 7.5 years). Two groups were analyzed prospectively: 93 children from which 1 - 3 mL of CSF (CSF-aspiration group) was aspirated before the injection of levobupivacaine to induce SA and 93 children from which no CSF was aspirated (no-CSF-aspiration group) prior to the injection of levobupivacaine. The main outcome measure was regression of the sensory block below T10, cephalic spread of the block, and postpuncture complications after SA.

Results

There were no between-group differences in the time to regression of the block below T10 or in the cephalic spread of the sensory block: 94 (27) minutes and T4.4 (SD 2.2) in the CSF-aspiration group, respectively, vs. 97 (29) minutes and T4.3 (1.8), respectively, in the no-CSF-aspiration group. Position-dependent headaches developed in 4 of 91 children in the CSF-aspiration group and 5 of 86 children in the no-CSF-aspiration group, but no epidural blood patches were required.

Conclusions

The aspiration of 1 - 3 mL of CSF before an injection of levobupivacaine did not seem to affect the spread and duration of the sensory block or postpuncture complications in children following SA.

Abdominal girth and vertebral column length can adjust spinal anesthesia for lower limb surgery, a prospective, observational study

Background

Studies have shown that abdominal girth and vertebral column length have high predictive value for spinal spread after administering a dose of plain bupivacaine. we designed a study to identify the specific correlations between abdominal girth, vertebral column length and a 0.5 % dosage of plain bupivacaine, which should provide a minimum upper block level (T₁₂) and a suitable upper block level (T₁₀) for lower limb surgeries.

Methods

A suitable dose of 0.5 % plain bupivacaine was administered intrathecally between the L₃ and L₄ vertebrae for lower limb surgeries. If the upper cephalad spread of the patient by loss of pinprick discrimination was T₁₂ or T₁₀, the patient was enrolled in this study. Five patient variables and intrathecal plain bupivacaine dose were recorded. Linear regression and multiple regression analyses were performed.

Results

Totals of 111 patients and 121 patients who lost pinprick discrimination at T₁₂ and T₁₀, respectively, were analyzed in this study. Linear regression analysis showed that only abdominal girth and plain bupivacaine dose were strongly correlated (r =−0.827 for T_12,r = −0.806 for T_10; both p < 0.0001). Multiple linear regression analysis showed that both abdominal girth and vertebral column length were the key determinants of plain bupivacaine dose (both p < 0.0001). R² was 0.874 and 0.860 for the loss of pinprick discrimination at T₁₂ and T₁₀, respectively.

Conclusions

Our data indicated that vertebral column length and abdominal girth were strongly correlated with the dosage of intrathecal plain bupivacaine for the loss of pinprick discrimination at T₁₂ and T₁₀. The two regression equations were Y_T12 = 3.547 + 0.045X₁-0.044X₂ and Y_T10 = 3.848 + 0.047X₁- 0.046X₂ (Y, 0.5 % plain bupivacaine volume; X₁, vertebral column length;and X₂, abdominal girth), which can accurately predict the minimum and suitable intrathecal bupivacaine dose for lower limb surgery to a great extent, separately.

In Spinal Anaesthesia for Cesarean Section the Temperature of Bupivacaine Affects the Onset of Shivering but Not the Incidence: A Randomized Control Trial

INTRODUCTION

Postoperative shivering is a frequent event after cesarean section under spinal anaesthesia. Shivering is uncomfortable for the patient and may interfere with monitoring. The exact aetiology of shivering is unknown and therefore has no definite treatment.

AIM

The temperature of injectate affects the spread of drug and so its effect. Therefore the aim of this study was to compare the effect of temperature of bupivacaine on post-spinal shivering in cesarean section.

MATERIALS AND METHODS

In this prospective, randomized, controlled, double-blind clinical trial 105 ASA-I/II pregnant women scheduled for caesarean section under spinal anaesthesia were selected and randomized into three groups of 35 each. In all pregnant women spinal anaesthesia was achieved with 2.2 ml of 0.5% hyperbaric bupivacaine given either at L3-L4 or L4-L5 interspace. The temperature of bupivacaine was adjusted to 4°C (group T4), 22°C (group T22) and 37°C (group T37). Shivering characteristic, onset and incidence was noted. All three groups were compared using analysis of variance (ANOVA), adverse effects was compared using chi-square test and Kruskal-Wallis H-test. The p-value < 0.05-considered as significant and p-value <0.01-considered highly significant.

RESULTS

There were no differences between the groups regarding age, weight, height, amount of fluid used and blood loss. The incidence of shivering was 51.42%, 51.42% and 45.71% in group T4, group T22 and group T37 respectively, this difference in the incidence was statistically not significant (p=0.858). However, the onset of shivering was earliest (9.87±1.82 min) in group T4 as compared to 14.27±3.02 min and 12.16±2.89 min in group T22 and group T37 respectively and this difference in the onset was highly significant (p= 0.0001).

CONCLUSION

In spinal anaesthesia for cesarean section, the temperature of bupivacaine does not influence the overall incidence of post spinal shivering; however cold bupivacaine can provoke early onset of shivering.

Anatomy of the Spinal Meninges

BACKGROUND

The spinal meninges have received less attention than the cranial meninges in the literature, although several points remain debatable and poorly understood, like their phylogenesis, their development, and their interactions with the spinal cord. Their constancy among the chordates shows their crucial importance in central nervous system homeostasis and suggests a role far beyond mechanical protection of the neuraxis.

OBJECTIVE

This work provides an extensive study of the spinal meninges, from an overview of their phylogenesis and embryology to a descriptive and topographic anatomy with clinical implications. It examines their involvement in spinal cord development, functioning, and repair.

METHODS

This work is a review of the literature using PubMed as a search engine on Medline.

RESULTS

The stages followed by the meninges along the phylogenesis could not be easily compared with their development in vertebrates for methodological aspects and convergence processes throughout evolution. The distinction between arachnoid and pia mater appeared controversial. Several points of descriptive anatomy remain debatable: the functional organization of the arterial network, and the venous and lymphatic drainages, considered differently by classical anatomic and neuroradiological approaches. Spinal meninges are involved in neurodevelopment and neurorepair producing neural stem cells and morphogens, in cerebrospinal fluid dynamics and neuraxis functioning by the synthesis of active molecules, and the elimination of waste products of central nervous system metabolism.

CONCLUSION

The spinal meninges should be considered as dynamic functional formations evolving over a lifetime, with ultrastructural features and functional interactions with the neuraxis remaining not fully understood.

COMPARISON BETWEEN MAGNETIC RESONANCE IMAGING ESTIMATES OF EXTRACRANIAL CEREBROSPINAL FLUID VOLUME AND PHYSICAL MEASUREMENTS IN HEALTHY DOGS

Dosages for myelography procedures in dogs are based on a hypothetical proportional relationship between bodyweight and cerebrospinal fluid (CSF) volume. Anecdotal radiographic evidence and recent studies have challenged the existence of such a defined relationship in dogs. The objectives of this prospective cross-sectional study were to describe CSF volumes using magnetic resonance imaging (MRI) in a group of clinically healthy dogs, measure the accuracy of MRI CSF volumes, and compare MRI CSF volumes with dog physical measurements. A sampling perfection with application optimized contrast using different flip-angle evolution MRI examination of the central nervous system was carried out on 12 healthy, male mongrel dogs, aged between 3 and 5 years with a bodyweight range of 7.5-35.0 kg. The images were processed with image analysis freeware (3D Slicer) in order to calculate the volume of extracranial CSF. Cylindrical phantoms of known volume were included in scans and used to calculate accuracy of MRI volume estimates. The accuracy of MRI volume estimates was 99.8%. Extracranial compartment CSF volumes ranged from 20.21 to 44.06 ml. Overall volume of the extracranial CSF increased linearly with bodyweight, but the proportional volume (ml/bodyweight kilograms) of the extracranial CSF was inversely proportional to bodyweight. Relative ratios of volumes in the cervical, thoracic, and lumbosacral regions were constant. Findings indicated that the current standard method of using body weight to calculate dosages of myelographic contrast agents in dogs may need to be revised.

Combined use of hyperbaric and hypobaric ropivacaine significantly improves hemodynamic characteristics in spinal anesthesia for caesarean section: a prospective, double-blind, randomized, controlled study

PURPOSE

To observe the hemodynamic changes of parturients in the combined use of hyperbaric (4 mg) and hypobaric (6 mg) ropivacaine during spinal anesthesia for caesarean section in this randomized double-blind study.

METHODS

Parturients (n = 136) undergoing elective cesarean delivery were randomly and equally allocated to receive either combined hyperbaric and hypobaric ropivacaine (Group A) or hyperbaric ropivacaine (Group B). Outcome measures were: hemodynamic characteristics, maximum height of sensory block, time to achieve T8 sensory blockade level, incidence of complications, Apgar scores at 1 and 5 min, and neonatal blood gas analysis.

RESULTS

Group A had a lower level of sensory blockade (T6 [T6-T7]) and longer time to achieve T8 sensory blockade level (8 ± 1.3 min) than did patients in Group B (T3 [T2-T4] and 5 ± 1.0 min, respectively; P < 0.001, both). The incidence rates for hypotension, nausea, and vomiting were significantly lower in Group A (13%, 10%, and 3%, respectively) than Group B (66%, 31%, and 13%; P < 0.001, P = 0.003, P = 0.028).

CONCLUSIONS

Combined use of hyperbaric (4 mg) and hypobaric (6 mg) ropivacaine significantly decreased the incidences of hypotension and complications in spinal anesthesia for caesarean section by extending induction time and decreasing the level of sensory blockade.

TRIAL REGISTRATION

Chinese Clinical Trial Register ChiCTR-TRC-13004622.

Importance and Impact of Preanalytical Variables on Alzheimer Disease Biomarker Concentrations in Cerebrospinal Fluid

BACKGROUND

Analyses of cerebrospinal fluid (CSF) biomarkers (β-amyloid protein, total tau protein, and hyperphosphorylated tau protein) are part of the diagnostic criteria of Alzheimer disease. Different preanalytical sample procedures contribute to variability of CSF biomarker concentrations, hampering between-laboratory comparisons. The aim of this study was to explore the influence of fractionated sampling, centrifugation, freezing temperature, freezing delay, and freeze–thaw cycles on CSF biomarker analyses.

METHODS

We studied fractionated sampling in sequential aliquots of lumbar CSF. Centrifuged and noncentrifuged samples from the same fraction were compared. CSF samples were subjected to different protocols (liquid nitrogen, −80 °C, and −20 °C; 24 h at 2–8 °C; and 24 and 48 h at room temperature). To study the influence of freeze–thaw cycles, samples were thawed up to 4 times and refrozen at −80 °C. CSF was collected in polypropylene tubes. We measured CSF biomarker concentrations with commercially available single-analyte Innotest assays.

RESULTS

CSF biomarker concentrations from non–blood-contaminated samples are not influenced by centrifugation or fractionated sampling. Freezing temperature and delayed storage can affect biomarker concentrations; freezing of CSF samples at −80 °C as soon as possible after collection is recommended. Consecutive freezing and thawing of CSF samples up to 3 times had little effect.

CONCLUSIONS

Temperature of freezing, delay until freezing, and freeze–thaw cycles significantly influence CSF biomarker concentrations, stressing the need for standard operating procedures for preanalytical sample handling. The differences observed in this study are, however, relatively small, and the impact on the clinical value of these CSF biomarkers needs to be determined.

Spinal hemianesthesia: Unilateral and posterior

The injection of a non-isobaric local anesthetic should induce a unilateral spinal anesthesia in patients in a lateral decubitus position. The posterior spinal hemianesthesia only be obtained with hypobaric solutions injected in the jackknife position. The most important factors to be considered when performing a spinal hemianesthesia are: type and gauge of the needle, density of the local anesthetic relative to the CSF, position of the patient, speed of administration of the solution, time of stay in position, and dose/concentration/volume of the anesthetic solution. The distance between the spinal roots on the right-left sides and anterior-posterior is, approximately, 10-15 mm. This distance allows performing unilateral spinal anesthesia or posterior spinal anesthesia. The great advantage of obtaining spinal hemianesthesia is the reduction of cardiovascular changes. Likewise, both the dorsal and unilateral sensory block predominates in relation to the motor block. Because of the numerous advantages of producing spinal hemianesthesia, anesthesiologists should apply this technique more often. This review considers the factors which are relevant, plausible and proven to obtain spinal hemianesthesia.

Bilateral Heel Numbness due to External Compression during Obstetric Epidural Analgesia

We describe the case of a 32-year-old woman who developed bilateral heel numbness after obstetric epidural analgesia. We diagnosed her with bilateral neuropathy of the medial calcaneal nerve, most likely due to longstanding pressure on both heels. Risk factors for the development of this neuropathy were prolonged labour with spinal analgesia and a continuation of analgesia during episiotomy. Padded footrests decrease pressure and can possibly prevent this neuropathy.

Cerebrospinal Fluid Volume and Nerve Root Vulnerability during Lumbar Puncture or Spinal Anaesthesia at Different Vertebral Levels

Cerebrospinal fluid (CSF) and nerve root volumes within the lumbosacral dural sac were estimated at various vertebral levels, in an attempt to determine any possible relevance to the incidence of nerve root trauma during lumbar puncture or spinal anaesthesia. Magnetic resonance images from seven patients were studied. Volumes were calculated by semi-automatic threshold segmentation combined with manual editing of each slice. The mean dural sac volume from S1 to T12 was 42.8±5.8 ml and the mean CSF volume 34.3±5.1 ml with the mean root volume being 10.4±2.2 cm3. The mean CSF volume per vertebral segment ranged from 4.3±0.7 ml at L5, to 5.8±2.5 ml at L1, with high inter-individual variability. The mean root volume ranged from 0.6±0.1 cm3 at L5 to 2.4±0.5 cm3 at T12.

The conus medullaris was located at L1 in four of the five patients scanned at upper lumbar levels, and at the lower border of L2 in the other. Vulnerability to nerve root damage was expressed as the Vulnerability Index (%), being defined as the ratio of root volume to dural sac volume (CSF volume + root volume). The value ranged between 7 and 14% at L5, increasing rostrally to 30 to 43% at T12. Caution is obviously required in high punctures to avoid contact with the conus medullaris, but the cauda equina is also vulnerable to contact with more caudal punctures and had a Vulnerability Index of about 25% at L4, that increased rostrally.

α-Synuclein in human cerebrospinal fluid is principally derived from neurons of the central nervous system

The source of Parkinson disease-linked α-synuclein (aSyn) in human cerebrospinal fluid (CSF) remains unknown. We decided to measure the concentration of aSyn and its gradient in human CSF specimens and compared it with serum to explore its origin. We correlated aSyn concentrations in CSF versus serum (Q(aSyn)) to the albumin quotient (Q(albumin)) to evaluate its relation to blood-CSF barrier function. We also compared aSyn with several other CSF constituents of either central or peripheral sources (or both) including albumin, neuron-specific enolase, β-trace protein and total protein content. Finally, we examined whether aSyn is present within the structures of the choroid plexus (CP). We observed that Q(aSyn) did not rise or fall with Q(albumin) values, a relative measure of blood-CSF barrier integrity. In our CSF gradient analyses, aSyn levels decreased slightly from rostral to caudal fractions, in parallel to the recorded changes for neuron-specific enolase; the opposite trend was recorded for total protein, albumin and β-trace protein. The latter showed higher concentrations in caudal CSF fractions due to the diffusion-mediated transfer of proteins from blood and leptomeninges into CSF in the lower regions of the spine. In postmortem sections of human brain, we detected highly variable aSyn reactivity within the epithelial cell layer of CP in patients diagnosed with a range of neurological diseases; however, in sections of mice that express only human SNCA alleles (and in those without any Snca gene expression), we detected no aSyn signal in the epithelial cells of the CP. We conclude from these complementary results that despite its higher levels in peripheral blood products, neurons of the brain and spinal cord represent the principal source of aSyn in human CSF.

Spinal cerebrospinal fluid volume in healthy elderly individuals

The amount of spinal cerebrospinal fluid (CSF) could be of importance for the understanding of CSF dynamics, CSF biomarker analyses as well as for the amount and effect of anaesthesia using intrathecally administered drugs. However, knowledge of spinal CSF volumes is scarce. The main purpose of this article is to present data on spinal CSF volumes. In total, 22 healthy individuals aged between 64 and 76 years underwent MR imaging with a 3D balanced turbo field echo pulse sequence, which provided high contrast between spinal cord, CSF and the extradural surroundings. The entire spinal CSF volume, the cervical, thoracic, and lumbosacral CSF volumes and the spinal cord volume were calculated. The total spinal CSF volume was 81 ± 13 ml (range 52-103 ml). The amount of CSF in the cervical region was 19 ± 4 ml, in the thoracic region 38 ± 8 and in the lumbosacral region 25 ± 7 ml. There was no difference between genders nor was there any correlation with height. The volume of the spinal cord was 20 ± 3 ml. The results present new magnetic resonance imaging-based data on the spinal CSF volume in healthy elderly individuals.

Uso de morfina intratecal en artrodesis lumbar

OBJETIVO: determinar la eficacia y la seguridad del uso de morfina intratecal, en bajas dosis, en pacientes sometidos a cirugía de instrumentación y artrodesis lumbar. MÉTODOS: estudio prospectivo, randomizado, ciego y controlado. Fueron utilizados dos grupos de pacientes: Grupo Estudio, que recibió morfina intratecal al final de su cirugía, y Grupo Control que sólo recibió el protocolo de analgesia estándar. RESULTADOS: se encontraron diferencias significativas en la escala visual análoga (EVA) entre los dos grupos a las 12 horas postoperatorias. La EVA en reposo promedio del Grupo Estudio fue de 2,15 cm y el del Grupo Control, 5 cm (p=0,013). En actividad, el Grupo Estudio presentó una EVA promedio de 4,36 cm, y el Grupo Control 6,9 cm (p=0,029). No se encontraron diferencias en relación a las complicaciones entre los dos grupos. CONCLUSIÓN: el uso de morfina intratecal, en bajas dosis, es seguro y efectivo en el control del dolor en las primeras 12 horas postoperatorias en cirugía de artrodesis lumbar.

Therapeutic effect of intrathecal morphine after posterior lumbar interbody fusion surgery: a prospective, double-blind, randomized study

STUDY DESIGN

Prospective, double-blind, randomized, placebo-controlled study.

OBJECTIVE

To assess the efficacy and safety of 0.4 mg intrathecal morphine for postoperative pain control after posterior lumbar interbody fusion (PLIF) surgery.

SUMMARY OF BACKGROUND DATA

Multiple studies have established the technique of intrathecal morphine analgesia in a wide variety of clinical settings. Several trials were conducted in patients undergoing spine surgery, generally supporting the efficacy for this type of surgery. Many exhibit methodologic problems with dosing regimes or study design.

METHODS

After the institutional review board-approval and written informed consent, 52 patients scheduled for PLIF-surgery were enrolled, of whom 46 could be analyzed. Patients were randomized to receive 0.4 mg morphine (M-group) or normal saline (P-group) intrathecally under direct vision before the end of surgery. Additionally, all patients received a piritramide patient-controlled-analgesia for individual pain control. Measures included visual analog scale-scores and blood-gas analysis over 20 hours after surgery. Morphine associated side effects and complications were recorded.

RESULTS

Visual analog scale-scores at rest and when the patients bent their legs were comparable between groups throughout the observation period, only being significantly lower in the M-group at rest 4 and 8 hours after surgery. Cumulative piritramide patient-controlled-analgesia requirements were significantly lower in the M-group throughout the observed 20 hours after surgery. Patients of the M-group were experiencing mild respiratory depression 4 hours after surgery not demanding any intervention, though. With respect to other morphine associated side effects or complications, there was no difference between the study groups.

CONCLUSION

We demonstrated the efficacy of 0.4 mg intrathecal morphine after PLIF-surgery as indicated by a significantly lower cumulative piritramide requirement without any serious increase of opioid associated side effects. Therefore, morphine in a dose of 0.4 mg administered intrathecally seems to be a viable alternative therapeutic option to provide postoperative analgesia with PLIF-surgery.

[Epidural and subarachnoid anesthesia and analgesia in adults: an update]

We present an update of the latest advances in clinical management and images of the most commonly used neuraxial techniques in epidural, subarachnoid, and combined spinal-epidural anesthesia and analgesia.