The Impact of Foramen Magnum Decompression With versus Without Duraplasty on Symptom Improvement and Syrinx Reduction in Chiari 1 Malformation Patients

Abstract

Introduction

Surgical decompression is considered the gold standard of treatment for patients with Chiari 1 malformation who are symptomatic or with syrinx. Currently, foramen magnum decompression with duraplasty (FMDD) and without duraplasty (FMD) are the two most commonly used techniques. This retrospective analysis aims to compare clinical improvement and syrinx reduction in patients undergoing FMDD versus FMD.

Materials and Methods

Clinical and radiological assessments were conducted pre- and postoperatively. Patient data was collected from electronic records and analyzed using univariate and multivariate regression analysis in R.

Results

Fifty-eight patients underwent FMDD and 38 patients underwent FMD. No difference in likelihood for symptom improvement (adjusted odds ratio [aOR] 0.96, p = 0.95) or syrinx reduction (aOR 1.69, p = 0.62) was seen between FMD and FMDD. Headaches were associated with increased likelihood for symptom improvement (aOR 4.83, p = 0.03), while unsteadiness (aOR 0.18, p = 0.03) and neck pain had lower likelihood for overall symptom improvement (aOR 0.23, p = 0.03). The presence of limb symptoms (aOR 16.45, p = 0.03) was associated with a higher likelihood while older age (aOR 0.95, p = 0.03) and male sex (aOR 0.04, p = 0.02) had lower likelihood for syrinx reduction. FMD was associated with a shorter length of stay (mean difference 1.94, p = 0.00).

Conclusion

No differences in overall symptom improvement or syrinx reduction were seen between patients undergoing FMD and FMDD. However, patients undergoing FMDD had longer lengths of stay in hospital. The lack of difference in symptom improvement and syrinx reduction may promote FMD as a better surgical technique. Furthermore, the role for individual symptoms in predicting symptom improvement and syrinx reduction was demonstrated. Larger studies will be required to validate which technique is better suited for patients with Chiari 1 malformations and to investigate the role of symptoms in predicting outcomes.

Keywords

Chiari 1 malformation - duraplasty - foramen magnum decompression - posterior fossa decompression - syringomyelia

Introduction

Chiari malformations, first described by Hans Chiari in 1891, are a group of defects associated with the displacement of the cerebellar tonsils through the foramen magnum into the upper cervical spinal canal.[1] The most commonly observed type is Chiari 1 malformation, which presents with symptoms such as headaches, neck pain, limb paraesthesia, and, less commonly, visual changes, unsteadiness, and syncope.[2] Surgical decompression is considered the gold standard of management; however, its success rate remains poorly defined.

Two techniques are generally employed for patients offered surgery: foramen magnum decompression with duraplasty (FMDD) and foramen magnum decompression without duraplasty (FMD). FMDD involves removal of the posterior arch of C1, widening of the foramen magnum, and release of the dura to open up space, followed by dural patching using autologous tissue or other materials. FMD is identical except that only the outermost layers of the dura are released.

FMDD is associated with longer operative times and higher complication rates but lower reoperation rates compared to FMD.[3] Despite ongoing research, evidence regarding the impact of these techniques on overall symptom improvement and syrinx reduction remains unclear. This retrospective analysis aims to determine the differences in clinical improvement and syrinx reduction between FMDD and FMD in patients with Chiari 1 malformation at a large tertiary referral centre in Aotearoa New Zealand (AoNZ).

Materials and Methods

Institutional review board approval for the design and conduct of this study was sought and granted by the Waikato Hospital Ethics Committee (number RD024049). Informed consent from patients was not required due to the retrospective design of this study.

Study Design and Setting

This retrospective cohort study was conducted at Waikato Hospital (Te Whatu Ora Waikato, Hamilton, AoNZ), which is a large tertiary-level and academic teaching institution comprising 759 inpatient beds, and provides complex subspecialty neurosurgical care to approximately 1 million patients in the Waikato and Midlands region of AoNZ.

Inclusion Criteria

All patients who underwent operative management for Chiari 1 malformation between January 1, 2010 and December 31, 2022 at Waikato Hospital were eligible for inclusion. Only symptomatic patients with Chiari 1 malformation, as evidenced by cerebellar tonsillar descent of 5 mm below the McRae line, with or without concurrent syrinx, or asymptomatic patients with concurrent syrinx with at least 4 mm cerebellar tonsillar descent, were included. Exclusion criteria included patients with other types of Chiari malformation and those who were transferred to other centers or migrated out-of-district and were thus lost to follow-up.

Relevant patients were identified from both electronic and paper medical records of all neurosurgical procedures pertaining to foramen magnum decompression and other synonymous terms, such as posterior fossa decompression, completed at Waikato Hospital during the specified study interval.

Operative Protocol

Patients were assessed clinically for symptoms and radiological evidence of Chiari 1 malformation with or without concurrent syrinx. Radiological assessment consisted of the presence of cerebellar descent and concurrent syrinx. Among asymptomatic patients, only those with radiological syrinx were offered surgery. Patients presenting closer to the establishment of the service underwent FMDD, while those presenting more recently underwent FMD. Other factors such as symptom severity and radiological findings did not contribute to the choice of procedure offered to patients. Furthermore, some patients initially planned for FMD underwent FMDD perioperatively due to inadequate decompression. During this period, patients were followed up by a brain/spine magnetic resonance imaging (MRI) between 3 and 6 months after surgery. In order to capture patients undergoing revisional surgery, follow-up was undertaken until 2 years.

Data Extraction

Extracted data included information on basic patient demographics (age at time of surgery, sex, and ethnicity), preoperative symptoms, radiological findings (e.g., presence or absence of syrinx preoperatively, syrinx reduction postoperatively, and extent of cerebellar tonsillar herniation), as well as postoperative complications.

Ethnicity were self-identified by patients and recorded at the time of operation, according to the AoNZ Ministry of Health ethnicity data collection protocols.[4] When more than one ethnicity was recorded, reporting was prioritized in the following order: indigenous Māori, Pacific peoples, Asian, and European/Other. For comparisons, patients were categorized into indigenous Māori and non-Māori strata.

Outcome Measures

The primary outcome was symptom improvement postoperatively. In the preoperative setting, each symptom was scored as 0 (absent) or 1 (present), and at 6-month postoperative follow-up as 0 (absent), 1 (present with no improvement), or 2 (present with improvement). Secondary outcomes included syrinx reduction at 6-month postoperative follow-up, postoperative length of stay (LOS), and overall as well as specific complications. Postoperative complications comprised wound infection, presence of pseudomeningocele on MRI, and the need for reoperation.

Statistical Analysis

All statistical analyses were conducted using RStudio (version 4.4.3; R Foundation for Statistical Computing, Vienna, Austria). Categorical variables were reported as frequencies (n) and percentage (%), while continuous variables were reported as the median and interquartile range for nonparametric data and mean ± standard deviation for normally distributed (parametric) data. Normality of data was investigated with the Shapiro–Wilk test. Continuous data were compared with the independent samples' t-test (for normally distributed variables) and Mann–Whitney U test (for nonparametric variables) and reported as the mean difference (MD). Categorical data were compared with the chi-squared test. Univariate and multivariate logistic regression analyses were conducted to assess for independent predictive factors of symptom improvement and syrinx reduction at 6-month postoperative follow-up. All explanatory variables with probability (p) values of ≤ 0.15 on univariable analyses were included in the multivariable logistic regression model in a forward stepwise approach. Overall effect estimates were presented as an odds ratio (OR) for univariate analyses, and adjusted OR (aOR) for multivariate analyses, with 95% confidence interval (CI). Effect estimates were considered statistically significant if the 95% CI did not cross the no-effect line of 1 for OR and 0 for MD.[5]

Results

Baseline Demographics

A total of 102 patients were identified, from which 6 patients were excluded as they underwent surgery for other types of Chiari malformation or were lost to follow-up and had incomplete data due to migration outside the Waikato Hospital region. Therefore, 96 patients underwent foramen magnum decompression over the 12-year study period, of which 58 (60.4%) patients underwent FMDD while 38 (39.6%) patients underwent FMD ([Table 1]).

Table 1 Baseline characteristics between patients who underwent foramen magnum decompression with versus without duraplasty

Characteristic	Total cohort (n = 96)	FMDD (n = 58)	FMD (n = 38)
Age at surgery (y), median (IQR)	31 (23–47.25)	32.5 (23–47.75)	31 (23.25–45.25)
Sex, n (%)
Male	25 (26)	14 (24)	11 (29)
Female	71 (74)	44 (76)	27 (71)
Ethnicity, n (%)
Indigenous Māori	38 (40)	24 (41)	14 (37)
Non-Māori	58 (60)	34 (59)	24 (63)
Preoperative symptoms, n (%)
Headache	77 (80)	45 (78)	32 (84)
Neck pain	25 (26)	17 (29)	8 (21)
Limb weakness or paraesthesia	66 (69)	44 (76)	22 (58)
Visual symptoms	21 (22)	8 (14)	13 (34)
Dizziness or vertigo	14 (15)	9 (16)	5 (13)
Nausea and vomiting	8 (8)	1 (2)	7 (18)
Syncope	10 (10)	4 (7)	6 (16)
Tinnitus	5 (5)	1 (2)	4 (11)
Unsteadiness	14 (14)	9 (16)	5 (13)
Speech or swallowing difficulty	8 (8)	4 (7)	4 (11)
Presence of syrinx, n (%)	47 (49)	30 (52)	17 (45)
Extent of cerebellar tonsillar herniation (mm), median (IQR)	10 (7–12)	10 (7–12)	8 (6.1–10)

Abbreviations: FMD, foramen magnum decompression without duraplasty; FMDD, foramen magnum decompression with duraplasty; IQR, interquartile range.

The median age of patients presenting for surgical decompression was 31 years. There was a female preponderance (74%), although self-identified ethnicity was similar among the two groups. Headaches were the most common symptom reported by patients, with almost 80% of patients from each group having these symptoms. This was followed by limb symptoms, including weakness and paraesthesia (69%), followed by neck pain (26%). Radiologically, almost half of patients had concurrent syrinx on MRI prior to surgery.

Primary Outcome

Overall Symptom Improvement

Overall, 79 (82%) patients undergoing foramen magnum decompression reported symptom improvement at 6-month follow-up. Results of the univariate and multivariate regression analyses are presented in [Table 2]. No difference in overall symptom improvement was found between those undergoing FMDD and FMD on univariate (OR 0.72, 95% CI: 0.18–4.74) or multivariate analysis (aOR 0.96, 95% CI: 0.24–3.80). Patients who were symptomatic with headaches were more likely to experience symptom improvement (aOR 4.83, 95% CI: 1.16–20.05), while those reporting neck pain (aOR 0.23, 95% CI: 0.06–0.84) and unsteadiness (aOR 0.18, 95% CI: 0.04–0.81) were less likely to report symptomatic improvement.

Table 2 Univariate and multivariate regression analysis for symptom improvement

Variable	Univariate analysis		Multivariate analysis[b]
	OR (95% CI)	p-Value	OR (95% CI)
Demographics
Age at surgery	0.97 (0.93–1.02)	0.26
Male sex	1.02 (0.20–6.36)	0.98
Non-Māori ethnicity	0.91 (0.23–3.43)	0.89
Preoperative symptoms
Headache	6.98 (1.52–37.7)	0.02	4.83 (1.16–20.05)
Neck pain	0.17 (0.03–0.74)	0.02	0.23 (0.06–0.84)
Limb weakness or paresthesias	1.98 (0.47–8.22)	0.60
Visual symptoms	0.18 (0.03–1.00)	0.05	0.35 (0.07–1.67)
Dizziness or vertigo	3.21 (0.41–71.72)	0.34
Nausea and vomiting	3.53 (0.29–101.95)	0.37
Syncope	1.04 (0.08–30.81)	0.98
Tinnitus	0.12 (0.01–2.94)	0.15	0.15 (0.01–1.83)
Unsteadiness	0.19 (0.03–1.20)	0.08	0.18 (0.04–0.81)
Speech or swallowing difficulty	0.59 (0.05–14.56)	0.69
Presence of syrinx	0.83 (0.18–4.74)	0.82
Extent of cerebellar tonsillar herniation	0.98 (0.88–1.11)	0.76
FMD[a]	0.72 (0.18–4.74)	0.82	0.96 (0.24–3.80)
Postoperative factors
Postoperative wound infection	0.98 (0.08–25.17)	0.99
Postoperative pseudomeningocoele	0.26 (0.04–1.76)	0.15	0.46 (0.07–2.96)
Postoperative complications	1.53 (0.22–17.52)	0.69
Syrinx reduction	1.13 (0.18–6.18)	0.89
Length of stay	0.90 (0.72–1.15)	0.38

Abbreviations: CI, confidence interval; FMD, foramen magnum decompression without duraplasty; OR, odds ratio.

^a FMD were included a priori in the multivariate regression analysis model.

^b Variables with p-values ≤ 0.20 on univariate analysis were included in the multivariate regression analysis model in a forward stepwise manner.

Syrinx Reduction

Overall, 32 (68%) patients with syrinx demonstrated reduction in size on postoperative MRI at 6 months. Univariate and multivariate regression analyses are detailed in [Table 3]. No difference in the degree of syrinx reduction was found between those undergoing FMDD and FMD on univariate (OR 1.49, 95% CI: 0.33–7.62) or multivariate analysis (aOR 1.69, 95% CI: 0.24–16.41). Patients experiencing limb weakness or paraesthesia preoperatively had an increased likelihood for syrinx reduction postoperatively (aOR 16.45, 95% CI: 1.83–287.13). Older age (aOR 0.95, 95% CI: 0.81–0.98) and male sex (aOR 0.04, 95% CI: 0.00–0.43) were associated with a reduced likelihood for syrinx reduction.

Table 3 Univariate and multivariate regression analysis for syrinx reduction

Variable	Univariate analysis		Multivariate analysis[b]
	OR (95% CI)	p-Value	OR (95% CI)
Demographics
Age at surgery	0.97 (0.92–1.01)	0.15	0.95 (0.81–0.98)
Male sex	0.21 (0.04–0.90)	0.04	0.04 (0.00–0.43)
Non-Māori Ethnicity	1.04 (0.27–4.18)	0.95
Preoperative symptoms
Headache	0.69 (0.17–3.03)	0.62
Neck pain	0.68 (0.17–2.56)	0.58
Limb weakness or paresthesias	9.51 (1.86–79.6)	0.02	16.45 (1.83–287.13)
Visual symptoms	0.14 (0.02–0.71)	0.03	0.08 (0.00–2.13)
Dizziness or vertigo	3.68 (0.18–75.85)	0.54
Nausea and vomiting	4.35 (0.22–100)	0.34
Syncope	0.12 (0.00–1.68)	0.17	NA
Tinnitus	NA
Unsteadiness	0.35 (0.02–2.87)	0.38
Speech or swallowing difficulty	6.28 (0.86–77)	0.10	NA
Extent of cerebellar tonsillar herniation[a]	0.98 (0.85–1.13)	0.78
FMD	1.49 (0.33–7.62)	0.61	1.69 (0.24–16.41)

Abbreviations: CI, confidence interval; FMD, foramen magnum decompression without duraplasty; OR, odds ratio.

^a Extent of cerebellar tonsillar herniation was included a priori in the multivariate regression analysis model.

^b Variables with p-values ≤ 0.20 on univariate analysis were included in the multivariate regression analysis model in a forward stepwise manner.

Secondary Outcomes

Overall and Specific Postoperative Complications

Postoperative complications occurred in 9 (9.4%) patients undergoing foramen magnum decompression ([Table 4]). There was no difference between FMD and FMDD regarding complication risk (5.3% vs. 12.1%; OR 0.41, 95% CI: 0.08–2.06). This was also the case for postoperative wound infections (0% vs. 8.6%; OR 0.13, 95% 0.01–2.35).

Table 4 Secondary outcomes between patients who underwent foramen magnum decompression without versus with duraplasty

Outcome	Total cohort (n = 96)	FMD (n = 38)	FMDD (n = 58)	Effect estimate (95% CI)
Postoperative complication(s), n (%)[a]	9 (9.4)	2 (5.3)	7 (12.1)	0.41 (0.08–2.06)[b] [c]
Postoperative infection, n (%)	5 (5.2)	0 (0.0)	5 (8.6)	0.13 (0.01–2.35)[b] [c]
Pseudomeningocoele on postoperative MRI, n (%)	8 (8.3)	0 (0.0)	8 (13.8)	0.08 (0.00–1.38)[b] [c]
Reoperation, n (%)	8 (8.3)	4 (10.5)	4 (6.9)	1.58 (0.27–9.09)[b] [c]
Mean postoperative length of stay (d)	5.18	4.00	5.95	–1.94 (–2.93 to –0.96)[b] [d]

Abbreviations: CI, confidence interval; FMD, foramen magnum decompression without duraplasty; FMDD, foramen magnum decompression with duraplasty; MRI, magnetic resonance imaging.

^a Comprising hydrocephalus (n = 1), benign intracranial hypertension (n = 1), cerebrospinal fluid (CSF) leak (n = 3), respiratory arrest (n = 1), pneumonia (n = 1), hygromas (n = 2).

^b Statistically significant differences are denoted by 95% CI which did not cross the no-effect line (0 for mean difference and 1 for odds ratio).

^c Odds ratio.

^d Mean difference.

Pseudomeningocele

Eight patients (8.3%) developed pseudomeningocele following foramen magnum decompression ([Table 4]). Risk of pseudomeningocele did not differ between FMD and FMDD (0% vs. 13.8%; OR 0.08, 95% CI: 0.00–1.38).

Postoperative LOS

Mean postoperative LOS after foramen magnum decompression was 5.2 days. Compared with FMDD, FMD was associated with significantly shorter postoperative LOS (4.00 vs. 5.95 days; MD –1.94 days, 95% CI: –2.93 to –0.96).

Reoperation

The overall rate of redo operations following foramen magnum decompression was 8.3% (n = 8). Risk of reoperation did not differ between FMD and FMDD (10.5% vs. 6.9%; OR 1.58, 95% CI: 0.27–9.09).

Discussion

Many studies have proposed guidelines and protocols to determine when surgery should be pursued, although further validation of these protocols is still required.[6] Among patients deemed suitable for surgery, this study aimed to clarify which surgical technique, FMDD or FMD, offer greater clinical improvement and syrinx reduction in patients with Chiari 1 malformation.

Although both clinical and radiological improvements are goals of surgical decompression, symptom improvement remains the primary objective. This study found that FMDD was associated with a higher likelihood of overall symptom improvement, although the difference between FMDD and FMD did not reach statistical significance. Several meta-analyses have demonstrated that FMDD has higher likelihood for symptom improvement.[6] However, other meta-analyses, such as those completed in the adult population show no equivalence for symptom improvement.[7] Thus, the existing literature presents conflicting findings regarding the optimal surgical technique for optimal clinical improvement, highlighting the need for high-quality evidence such as randomized controlled trials. Furthermore, long-term clinical improvement is also indirectly measured through the need for redo operation. No statistically significant difference in redo operation rates was seen between the FMDD and FMD. While most studies contradict these findings, the apparent difference in redo operations may relate to the intrinsic nature of technique employed. FMD is a less extensive procedure, and there is opportunity for further duraplasty if revisional surgery is required, while FMDD is generally more extensive which limits the extent of further intervention.[8]

To the best of the authors' knowledge, this is the first study to highlight preoperative symptoms as predictive of treatment efficacy in terms of symptomatic improvement or radiological evidence of syrinx reduction. Notably, the presence of limb weakness or paraesthesia was associated with a significantly increased likelihood of syrinx reduction. One possible explanation is that these patients may have had a pressure-transmitting syrinx involving the spinothalamic or anterior horn tracts, which is more amenable to collapse following decompression.[9] Additionally, preoperative headaches were associated with greater likelihood of symptom improvement, whereas patients reporting neck pain were less likely to benefit symptomatically on multivariate analysis. Although the underlying mechanisms remain unclear, headaches may identify a subgroup of patients who are more responsive to decompression, while isolated neck pain in the absence of neurological symptoms may reflect a more complex Chiari malformation phenotype that is less responsive to surgical decompression.[10]

As seen with prior studies, older age was negatively associated with syrinx reduction.[11] We have also demonstrated sex as independently predicting a reduced likelihood of syrinx reduction, which has not been identified previously. With relation to the surgical technique employed, no significant difference was seen for syrinx reduction although FMD had a trend for higher likelihood for syrinx reduction (aOR 1.49 [0.33–7.62]). Chai et al reported FMDD as being associated with an increased likelihood of syrinx reduction, while Förander et al and Lu et al (pediatric) found no difference between the FMD and FMDD groups.[8] [12] [13] With further stratification by age, Chai et al did note that this effect was only seen within the adult population. However, given these meta-analyses draw from very small and heterogeneous studies, conclusions are difficult to make due to the scarcity of available literature.

Postoperative wound infections and pseudomeningocoele development were only seen in patients undergoing FMDD. Although not statistically significant, this finding was consistent with prior studies.[6] What may be important to extract from this is that both groups report minimal differences in overall complications, but differences arising from the risks inherent to the technique employed are likely to be seen with larger groups.[6] [8] Importantly, patients undergoing FMD had shorter LOSs compared to those undergoing FMDD. Given no significant differences were seen between clinical symptoms, syrinx reduction, and postoperative complications, this finding supports FMD as potentially having resource-saving implications.

There are several limitations to this study. First, the retrospective and single-center design introduces selection bias and limits the generalizability of our findings. To mitigate this, the study were conducted at Waikato Hospital, which is one of the largest tertiary referral centers in AoNZ, and is the only institution to provide neurosurgical service to the Midlands and Waikato region of AoNZ. Inherently, following foramen magnum decompression surgery, a small proportion of patients included within our study may be returned to their home domicile for repatriation and convalescence. As a result, this introduces risk of attrition bias as patients may be lost to follow-up, potentially leading to under- or overestimation of our findings. However, this is unlikely to substantially influence our overall results as only six patients (< 5% of the overall cohort) had incomplete follow-up data. Second, the small sample size of our cohort has resulted in imprecise effect estimates, with some analyses having extremely wide 95% CI. Consequently, outcomes considered to be statistically significant should be interpreted with caution. Third, symptom improvement in the postoperative period was assessed via chart review of electronic and handwritten records, which introduces subjectivity, interobserver variability, and limits comparability between other centers and institutions. Future studies should utilize standardized and validated instruments such as the Chicago Chiari Outcome Scale, to improve reliability and facilitate reproducibility of results.[14] Fourth, the study was conducted over a 12-year period (2010–2022), which potentially also introduces temporal confounding resulting from a time period bias, as evolving surgical expertise, perioperative care, and imaging capacity and advent of novel technology could influence outcomes independently of surgical technique. However, due to the infrequent occurrence of Chiari 1 malformation, this study interval was selected to ensure comprehensive inclusion of all patients with Chiari 1 malformation at our institution. Lastly, only operatively managed patients were included, and while surgical decision-making is typically guided by symptom duration and severity, individual surgeon judgment may also have an influence.[15] Notwithstanding, we aimed to examine the clinical and radiological efficacy of two different surgical techniques for foraminal decompression, and thus the natural history and outcomes of patients with Chiari 1 malformation managed conservatively was outside the scope of our present study.

Conclusion

This analysis did not identify any difference in symptom improvement and radiological evidence of syrinx reduction among patients with Chiari 1 malformation undergoing FMD compared with FMDD. Interestingly, preoperative unsteadiness and neck pain was predictive of a poor outcome, whereas patients with headache were more likely to experience symptomatic improvement postoperatively, irrespective of surgical technique. Additionally, presence of limb weakness or paraesthesia was associated with syrinx reduction. These findings suggest that there may be a subset of patients with Chiari 1 malformation who are more or less responsive to surgical decompression irrespective of the technique employed, supporting the need for accurate patient selection when determining potential operative candidates. Furthermore, FMD was associated with significantly shorter postoperative LOS without any differential risk of postoperative complications or reoperation, supporting this technique as potentially having resource-saving and economic implications. Larger prospective studies will be required to corroborate and validate our findings.

Conflict of Interest

Dr. Sung-Min Jun reported receiving academic supervision/support from Dr. Peter Yee Chiung Gan for this research article.

Note

This manuscript was presented as an oral presentation at the Society of British Neurosurgical Surgeons Autumn Meeting, Birmingham, on Thursday, September 26, 2024.

Authors' Contributions

SM. J. was responsible for data collection, data analysis, and manuscript preparation and served as the primary author. SH. K. contributed to manuscript preparation. D.J. assisted with data collection, while S.B. performed the statistical analysis. H.L. contributed to the design and execution of the analysis, assisted with data interpretation, and reviewed the manuscript. P.G. conceived and designed the analysis, reviewed the manuscript, and served as the corresponding author.

Ethical Approval

This research project was review and given locality/ethical approval by the Health New Zealand | Te Whatu Ora Waikato Hospital Research Office (Project number: RD024049).

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Publication History

Article published online:
09 December 2025