Abstract
Study Design
Prospective cohort study.
Objective
Postoperative cerebrospinal fluid leakage (CSFL) is a common complication following thoracic spinal stenosis (TSS) surgery. This study aimed to evaluate the therapeutic effects of different fluid supplementation strategies on intracranial hypotension symptoms (IHS) caused by CSFL.
Methods
Patients who developed CSFL after TSS surgery at a single center over a 3-year period were prospectively enrolled. All patients received standardized postural and drainage management. In addition, they were administered either low-sodium or high-sodium solution supplementation alongside standard medications. The incidence and severity of IHS and changes of blood electrolyte levels were compared between the two groups.
Results
The incidence of IHS in low-sodium group is 57.5%, and in high-sodium group is 40% (P = .117). Although, there was no statistically significant difference in the improvement of IHS between the two fluid supplementation strategies. However, statistical differences in blood electrolyte levels were observed. On postoperative days 2 and 3, serum sodium levels were significantly lower in the low-sodium group (139.9 ± 2.08 vs 141.1 ± 3.1, P = .022; 140.0 ± 3.0 vs 141.25 ± 3.85, P = .034).
Conclusion
While high-sodium fluid supplementation tended to reduce the incidence of IHS following CSFL, the difference compared to low-sodium fluids was not statistically significant. Nonetheless, the observed differences in electrolyte level of sodium suggest a potential physiological impact. Further studies with larger sample sizes are needed to confirm these findings.
Keywords
Introduction
Thoracic spinal stenosis (TSS) is a condition for which conservative treatment options are limited, and surgical decompression remains the most effective intervention. However, due to the complex anatomical structure and vulnerability of the thoracic spinal cord, surgical procedures are technically demanding and carry a high risk of complications. Among these, cerebrospinal fluid leakage (CSFL) is one of the most frequently encountered issues. 1
The reported incidence of postoperative CSFL varies significantly depending on the pathogenic factors. In patients with thoracic ossification of the ligamentum flavum (TOLF), the incidence ranges from 12.1% to 32.0%2-6; for those with thoracic ossification of the posterior longitudinal ligament (TOPLL), it ranges from 23.8% to 58.8%7-10; and in cases involving both conditions, the incidence ranges from18.6% to 70.8%.11-13 One of the most troublesome sequelae of CSFL is intracranial hypotension symptoms (IHS), which include headache, dizziness, nausea, and vomiting, and can cause the patients a lot of pain. 14
While intraoperative dural tears are often managed with various sealing materials, the irregular nature of dural damage often leads to low repair success rates.2,15 As a result, postoperative management of CSFL becomes critically important. This typically involves a combination of drainage control, administration of patient positioning, and fluid supplementation. 16 Among these, the choice of fluid supplementation—particularly regarding sodium concentration—varies considerably among clinicians. Commonly used regimens include isotonic saline (0.9%) or saline solutions with added sodium chloride. However, to date, there is a lack of high-quality comparative studies evaluating their relative effectiveness.
Therefore, this prospective study was designed to compare the clinical outcomes of low-sodium and high-sodium fluid supplementation in the management of postoperative CSFL and associated IHS in patients undergoing surgery for TSS.
Materials and Methods
The Ethical Committee of our hospital approved this research (IRB00006761-M2023267). From January 2023 to January 2025, patients who developed CSFL following TSS decompression surgery at a single center were enrolled. CSFL was diagnosed based on: (i) Confirmed dural tear or visible CSF outflow during operation, (ii) Postoperative drainage fluid appearing as pale bloody or clear fluid with high volume, (iii) Continuous clear or pale bloody discharge from the wound, (vi) Large volume of clear or pale bloody fluid extracted by subcutaneous aspiration at the wound region.2,17 And blood electrolyte levels were monitored daily postoperatively.
Once CSFL was confirmed, patients were assigned to receive either low-sodium or high-sodium fluid supplementation in addition to standard medications. Fluid supplementation was continued until removal of the drainage tube. Regimens were rotated every 6 months to minimize time-related biases. Patients in low-sodium group received 2000 mL of 5% glucose saline daily (reduced to 1500 mL for elderly patients to prevent cardiac overload). Patients in high-sodium group received 1000 mL of 5% glucose saline with 6 g of NaCl, plus an additional 1000 mL of 5% glucose saline daily (reduced to 500 mL of 5% glucose saline for elderly patients).
IHS was assessed starting from postoperative day 1. Standardized postural management was applied: patients remained in a normal supine position initially and were switched to flat bed rest without a pillow after attack of IHS. Drainage was set to normal pressure 24 h after surgery, with the drainage bag placed at bed level. IHS was assessed as follows. Headache was measured using visual analogue scale (VAS) score. Dizziness was graded as: Grade I (intermittent), Grade II (continuous). Nausea/Vomiting grading: Grade I: mild nausea, Grade II: evident nausea, no vomiting, Grade III: severe vomiting, requires medication.
A double-blind design was implemented: both patients and researchers assessing outcomes were unaware of the assigned fluid regimen.
Quantitative variables that followed a normal distribution were analyzed using the independent t-test, while severely skewed variables were analyzed using the Wilcoxon rank-sum test. Categorical data were analyzed using the Chi-Squared test. Data subjected to normal distribution are presented as mean ± standard deviation and skewed data as median (interquartile range). Statistical analyses were performed using Statistical Package for the Social Sciences software version 25.0 (IBM SPSS Statistics 25), with P-values <.05 considered statistically significant.
Results
The Demographic Characteristics and Basic Data of Operation Among Two Groups
The Daily Drainage Volume and Fluid Supplementation Volume of the Patients After the Surgery
OP, the day of operation; D1, the first day after operation, and so forth.
The Assessment of Low Intracranial Pressure Symptoms After Cerebrospinal Fluid Leakage
Comparison of Details of Symptoms of Low Intracranial Pressure
Effects of Different Fluid Replacement Methods on Blood Electrolytes
OP, the day of operation; D1, the first day after operation, and so forth.
Discussion
The administrations of patients with CSFL after surgery for TSS include: drainage control, administration of patient positioning, and fluid supplementation with the aim to maintain the balance of cerebrospinal fluid secretion and outflow. However, there remains no consensus or high-quality evidence regarding the optimal fluid supplementation strategy. So, we conducted this prospective study to evaluate the effects of low-sodium and high-sodium fluid supplementation on IHS following CSFL after TSS decompression surgery.
The exact mechanism of CSF production is not fully understood. The widely accepted model suggests that sodium-potassium pumps in the choroid plexus drive sodium into the CSF, creating an osmotic gradient that pulls hydrone into the ventricles.18-20 Sodium influx into the CSF occurs primarily through Na+-K+-ATPase, which maintains low intracellular sodium concentrations, generating a basolateral gradient that promotes further sodium uptake into choroid plexus cells via channels such as the Na+/H+ exchanger and Na+-HCO3- cotransporter. 21 Bouzinova EV, et al 22 demonstrated that the removal of extracellular sodium in rat choroid plexus cells resulted in intracellular acidification, which was reversed upon sodium reintroduction—suggesting that Na+-dependent HCO3- transport regulates cellular pH and potentially influences CSF secretion. Although the exact mechanism of cerebrospinal fluid secretion has not yet been fully studied, sodium ions are clearly playing a very significant role. So, we speculated that fluid supplementation strategies of different sodium concentration might affect the balance of cerebrospinal fluid secretion and outflow and further affect the incidence of IHS.
In this study, the overall incidence of IHS after CSFL is 48.75%, and this is the first study to investigate the incidence of IHS caused by CSFL after TSS decompression surgery. And, the high-sodium group demonstrated a lower incidence of IHS compared to the low-sodium group, with no statistical difference (40% vs 57.5%, P = .117). In addition, differences in electrolyte levels were observed. On the second and third days after the operation, the low-sodium group had lower blood sodium values (139.9(2.08) vs 141.1(3.1), P = .022; 140(3) vs 141.25(3.85), P = .034). Therefore, with similar drainage volumes in the two groups, we speculated that high-sodium fluids may enhance CSF production. And the possible cause of no statistical difference in the incidence of IHS is that the sample size is still small.
Notably, this is the first large-sample, prospective study to directly compare different sodium concentrations in postoperative fluid supplementation for CSFL-related IHS in TSS patients. The study design minimized confounding factors by employing standardized drainage management, postural protocols, and a double-blind approach. Despite these strengths, several limitations must be acknowledged. First, the sample size was not determined based on scientific analysis, due to the lack of prior reference data. Second, while fluid regimens were alternated every 6 months to reduce bias, some residual time-based confounding may remain. Finally, this single-center design may limit the generalizability of the findings to other clinical settings.
Conclusion
There is a tendency that high-sodium fluid supplementation for patients after thoracic spinal decompression can decrease the incidence of intracranial hypotension after cerebrospinal fluid leakage, compared with low-sodium fluid supplementation——just a non-significant trend, and this finding is exploratory. Notably, high-sodium fluids led to higher changes in serum sodium levels, which may potentially influence cerebrospinal fluid dynamics. However, there is no statistically difference between low-sodium and high-sodium fluids in the treatment. Further research with more subjects is required.
Footnotes
Ethical Consideration
The Ethical Committee of Peking University Third Hospital approved this research (IRB00006761). Written informed consent and consent for publication were obtained.
Author Contributions
Zixuan Xu wrote this article; Guanghui Chen collected the data. Lei Yuan, Longjie Wang and Shuai Jiang analysed the data. Zhaoqing Guo and Qiang Qi polished this manuscript. Hongling Chu calculated the sample size and provided guidance on statistics. Zhongqiang Chen and Weishi Li designed the study. Feifei Zhou and Chuiguo Sun guide the entire research.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was funded by Peking University Third Hospital Talent Incubation Fund (Grant Number: Y77477-03) and The Peking University Third Hospital Clinical Cohort Project (Grant Number: BYSYDL2022009) and Natural Science Foundation of Beijing Municipality (Grant Number: 7252164).
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Data Availability Statement
All data will be retained in Peking University Third Hospital and the research group. The datasets generated during the current study are not publicly available but are available from the corresponding author on reasonable request.