Cerebrospinal fluid leak following traumatic skull base fractures: Predictors and outcomes

Abstract

Background:

Traumatic skull base fractures carry a risk of cerebrospinal fluid (CSF) leak, predisposing patients to meningitis, neurological complications, and prolonged hospitalization. Predictive factors for posttraumatic CSF leak remain incompletely defined. The primary objective of this study is to identify clinical and radiological predictors of CSF leak among patients with traumatic skull base fractures and evaluate associated outcomes at a Level-1 trauma center.

Methods:

A retrospective cohort study was conducted at King Abdulaziz Medical City, Riyadh, including all patients with computed tomography-confirmed skull base fractures from 2016 to 2024. Demographics, injury characteristics, management variables, and complications were extracted from the trauma registry and electronic medical records. Bivariate comparisons and logistic regression were performed to determine independent predictors of CSF leak.

Results:

Among 499 patients, 36 (7.2%) developed a CSF leak. Mixed temporal fractures and pneumocephalus were independent predictors of CSF leak. CSF leak was associated with significantly higher rates of meningitis (11.1% vs. 0.9%), cranial nerve deficits (19.4% vs. 4.8%), and internal carotid artery injury (13.9% vs. 3.7%) (all P < 0.05). Median hospital stay was longer in patients with CSF leak (23.5 vs. 14 days, P = 0.038).

Conclusion:

Mixed temporal bone fracture patterns and pneumocephalus are strong predictors of posttraumatic CSF leak, while the presence of meningitis and cranial nerve deficits reflects more severe injury and increased morbidity. Structural fracture complexity and radiologic markers appear more informative than fracture location alone. Early recognition, risk-based monitoring, and timely multidisciplinary management are essential to mitigate infectious and neurological sequelae.

INTRODUCTION

Traumatic skull base fractures account for a major part of head injuries, most commonly after accidents, such as a motor vehicle crash or falls. The intricate anatomy of the skull base, paranasal sinuses, and middle ear makes such fractures susceptible to cerebrospinal fluid (CSF) leaks and subsequent morbidity, such as meningitis, pneumocephalus, and long-term neurological morbidity.[5] A CSF leak may occur in 2–25% after skull base fractures and depends on the fracture site, trauma etiology, and diagnostic methods.[8]

Recent studies have emphasized the importance of fracture anatomy and patient demographics for predicting CSF leaks. As reported by a cross-sectional study in 2025, anterior cranial fossa fractures and male gender show a significant association with posttraumatic CSF leaks.[16] Among pneumocephalus patients, 14% have CSF leaks, particularly those with frontobasal fractures due to car accidents.[10] Studies additionally indicate a correlation between low scores on the Glasgow Coma Scale (GCS), severe head injuries, and the risk of CSF leaks.[4]

Management approaches usually start with conservative interventions, such as bed rest, head elevation, and avoidance of straining activities because a large fraction of all these leaks are self-resolving.[13] Chronic or recurring leaks typically require a surgical repair of the skull base to restore skull base integrity and prevent intracranial infection.[11,13]

In addition to the underlying morbidities associated with the acute trauma, skull base fractures linked to CSF leak often lead to worse survival conditions such as longer hospitalization-related admissions and a higher rate of mortality in patients with traumatic brain injury.[9] In addition, the involvement of several cranial compartments or comminuted fracture patterns also negatively impacts prognosis and neurologic recovery.[21]

Given these complications, predicting posttraumatic CSF leak is of utmost importance. Prior studies described fracture location (especially anterior cranial fossa), temporal bone engagement, mixed fracture nature, and related pneumocephalus as risk factors.[7,19]

Therefore, this study aims to identify clinical and radiological predictors of CSF leak among patients with traumatic skull base fractures and to assess its impact on hospital outcomes and overall morbidity at a Level-1 trauma center.

MATERIALS AND METHODS

Patients eligibility

This is a retrospective observational cohort study designed to analyze the clinical characteristics, management, and outcomes of patients with skull base fractures, with a particular focus on identifying factors associated with the development of CSF leak. The study retrospectively reviewed records from January 2016 to December 2024. This study included patients with computed tomography (CT)-confirmed skull base fractures. Those admitted for nontraumatic reasons or transfers from other hospitals were excluded.

Study setting

The study was carried out at King Abdulaziz Medical City (KAMC) in Riyadh, a Level 1 trauma center that provides specialized care. KAMC is fully equipped to manage all forms of traumatic injuries, including complex cases such as polytrauma, severe head injuries, and spinal cord trauma. The institution maintains a comprehensive trauma registry that records all patients admitted due to traumatic incidents.

Data acquisition

Data were obtained from the trauma registry and verified using the electronic medical records at King Abdulaziz Medical City (KAMC), Riyadh. The collected data included the mechanism of injury, patient demographics (age and gender), vital signs on presentation (heart rate, respiratory rate, and systolic blood pressure), and neurological status assessed by the GCS. Additional variables included need for craniotomy, intubation period (days), intensive care unit (ICU) length of stay (days), hospital disposition, and total hospital length of stay. Injury-related variables included the location of skull fracture, temporal bone fracture pattern, and the presence of CSF leak. Data were also collected on meningitis occurrence, cranial nerve deficits (including the specific nerve affected and whether the deficit resolved), internal carotid artery (ICA) injury detected on CT angiography, and the presence of pneumocephalus. Temporal bone fracture classification was based on CT imaging and followed the traditional radiologic criteria according to fracture orientation relative to the long axis of the petrous temporal bone.

Statistical analysis

Descriptive statistics were used to summarize demographic, clinical, and management-related characteristics. Categorical variables were presented as frequencies and percentages, while continuous variables were summarized using medians and interquartile ranges (IQRs). Comparisons between patients with and without CSF leak were conducted using Pearson’s Chi-squared test or Fisher’s exact test for categorical variables and the Wilcoxon rank-sum test for continuous variables. A two-sided P < 0.05 was considered statistically significant. Variables that showed statistical significance in the bivariate analysis were included as independent variables in a multivariable logistic regression model, with CSF leak specified as the dependent variable. Firth’s penalized logistic regression was used to account for potential small-sample bias. All analyses were performed using RStudio (version 2024.9.1.394, Boston, MA, USA) with R version 4.4.2.

RESULTS

Demographic and clinical characteristics

A total of 499 patients were included. Most patients were aged 18–<30 years (44.1%) and were male (91.6%). Nearly half of the patients presented with severe head injury based on the GCS (49.5%). The most common mechanism was from motor vehicle accidents (67.1%). The middle cranial fossa was the most common fracture location (42.3%). Among those with temporal fractures, longitudinal patterns were the most frequent (52.6%) [Table 1].

Table 1:

Demographic and clinical characteristics of all patients with skull base fractures.

Characteristics of CSF leak and the associated factors

Out of 499 patients with skull base fractures, 36 (7.2%) had a documented CSF leak. The mechanism of injury was significantly associated with the presence of CSF leak (P = 0.038), with motor vehicle accidents being more common among patients with CSF leak (91.7%) compared to those without (65.2%). A higher proportion of patients with CSF leak had mixed temporal bone fractures (17.6%) compared to those without CSF leak (4.4%, P = 0.006) [Table 2].

Table 2:

Statistical differences between patients with and without CSF leak in terms of demographic and clinical characteristics.

Hospital course, management, and interventions

Among all patients, more than half were admitted to the ICU (55.3%). Craniotomy was performed in 18.6% of patients. The median intubation period was 4.0 days (IQR = 0.0–10.0), ICU length of stay was 7.0 days (IQR = 0.0–14.0), and hospital length of stay was 15.0 days (IQR = 6.0–35.0). Most patients were discharged home (82.4%), while 11.0% passed away during hospitalization [Table 3]. Patients with CSF leak had a longer hospital stay (median = 23.5 days, IQR = 9.0–57.5) compared to those without CSF leak (median = 14.0 days, IQR = 6.0 to 32.0; P = 0.038).

Table 3:

Statistical differences between patients with and without CSF leak in terms of the characteristics of hospital course, management, and interventions.

Clinical complications

Among all patients, meningitis occurred in 1.6%, cranial nerve deficits in 5.8%, and pneumocephalus in 21.7%. ICA injury identified on CT angiography was found in 4.4% of patients, while 80.1% had no angiographic imaging performed.

Patients with CSF leak had significantly higher rates of meningitis (11.1% vs. 0.9%, P = 0.001), cranial nerve deficits (19.4% vs. 4.8%, P = 0.003), and pneumocephalus (55.6% vs. 19.0%, P < 0.001) compared to those without CSF leak. Cranial nerve deficit resolution also differed significantly (P = 0.001), with unresolved cases more common in the CSF leak group (8.3% vs. 2.8%). In addition, ICA injury was more frequently detected in patients with CSF leak (13.9% vs. 3.7%, P = 0.016) [Table 4].

Table 4:

Statistical differences between patients with and without CSF leak in terms of the clinical complications.

Predictors of CSF leak

In the multivariable analysis, several variables were independently associated with the presence of CSF leak. Compared to motor vehicle accidents, pedestrian injuries were associated with lower odds of CSF leak (odds ratio [OR] = 0.19, 95% confidence interval [CI], 0.02–0.93, P = 0.040). Patients with mixed temporal fractures had higher odds of CSF leak (OR = 3.66, 95% CI, 1.13–10.8, P = 0.032). Cranial nerve deficits were also significantly associated with CSF leak (OR = 3.42, 95% CI, 1.11–9.83, P = 0.033). Pneumocephalus was strongly associated with CSF leak (OR = 6.24, 95% CI, 2.92–13.8, P < 0.001) [Table 5].

Table 5:

Predictors of CSF leak for patients with skull base fractures.

DISCUSSION

In this retrospective cohort of patients with traumatic skull base fractures, mixed temporal fracture and pneumocephalus were identified as independent predictors of CSF leak, while meningitis and cranial nerve deficits represented significant associated complications. The overall incidence of CSF leak was found to be 7.2%, aligning with recent reports ranging from 2% to 4%.[4,12,19]

In the present study, mixed temporal bone fracture emerged as an independent risk factor for CSF leakage. This is consistent with the findings of Steele et al.[18] who also observed a higher risk of CSF leak in association with temporal bone fractures. The recognition of mixed temporal fractures as the strongest structural predictor of CSF leak emphasizes the role of fracture complexity and multidirectional propagation rather than simple anatomic location. Previous imaging-based analyses show that fractures involving both longitudinal and transverse components of the temporal bone often extend through the otic capsule and petrous ridge, regions intimately related to the dura and venous sinuses.[1,15] Such configurations predispose to direct dural tears and communication between the subarachnoid and air-containing spaces, explaining their strong association with CSF otorrhea. Hussein et al.,[6] similarly observed that fracture complexity and multiple-segment involvement, rather than isolated site, were the most consistent predictors of leak and meningitis. Together, these data and the present results show that fracture pattern and energy distribution are more reliable determinants of dural breach than anterior versus posterior classification alone.

Pneumocephalus demonstrated a strong association with CSF leak in the present cohort (OR = 6.24, P < 0.001). This association stresses the clinical relevance of radiologic findings in identifying dural disruption. Pneumocephalus reflects the entry of air through a skull base defect into the intracranial cavity, and in the context of trauma, strongly suggests the presence of dural tear even before clinical leakage becomes evident. Moreover, pneumocephalus was noted among the common complications of skull base trauma, often accompanying dural violation and infection.[6] The current data therefore reinforces the role of early CT evaluation not only for the fracture classification, but also for recognizing secondary signs such as intracranial air that correlate with an underlying CSF fistula and justify early neurosurgical assessment. It is important to clarify that pneumocephalus should not be interpreted as an independent etiologic factor, but rather as a radiologic marker of dural breach and communication with adjacent air-containing spaces. In the setting of skull base trauma, pneumocephalus is frequently detected on initial CT imaging before overt rhinorrhea or otorrhea becomes evident, thereby functioning as an early imaging indicator of patients at high risk for clinically manifest CSF leakage.

Meningitis was found to be strongly associated with CSF leak, reaffirming its role as the most serious complication of traumatic dural tears. Historical and recent studies consistently report meningitis rates between 1% and 10% in skull base fracture patients, with the risk rising substantially in persistent or untreated leaks.[12] Conservative management was successful in most early leaks, but prolonged leakage beyond 5 days markedly increased the likelihood of meningitis.[22] Comparably, McCutcheon et al.[12] noted that patients with CSF leaks requiring surgical repair exhibited meningitis rates as high as 4.3%, compared to less than 1% in those without leaks. The current study findings are in line with these observations, emphasizing that prevention of infection relies heavily on early recognition and timely closure of dural defects.

Cranial nerve deficits were another important independent predictor, observed in approximately 19% of patients with CSF leak compared to 5% in those without (P = 0.003). Temporal bone fractures were frequently implicated in facial (VII) nerve injury, correlating with Steele et al.[18] who identified the occurrence of facial nerve injury in 6.9% of those with temporal bone fractures. Furthermore, Wamkpah et al.[20] reported that facial paralysis after skull base trauma occurred in 1% of cases, with a high rate of concomitant CSF leak and hearing loss, aligning with the pattern observed in the present study. In addition, Hussein et al.[6] described cranial nerve palsies as markers of severe basal disruption and poor functional recovery. These findings collectively support the interpretation that the presence of a neurological deficit indicates a more complex and higher energy trauma pattern with increased likelihood of dural breach.

Interestingly, pedestrian injuries were negatively associated with CSF leak (OR = 0.19, P = 0.040). This inverse relationship likely reflects the lower kinetic energy transfer typical of pedestrian impact compared with high velocity motor vehicle collisions, which produce more extensive skull base fragmentation and dural tearing.[4] Mechanism-dependent risk stratification is thus essential in early trauma assessment, as it can help prioritize imaging and prophylactic monitoring for CSF leakage.

The present results support an anatomy and risk-guided management approach to posttraumatic CSF leak. Conservative treatment remains appropriate for low-flow leaks and early cases, with bed rest, head elevation, and bowel regimens as standard initial measures.[14,22] However, leak persistence beyond 3 days or the presence of mixed temporal fracture should prompt early surgical evaluation. Piccirilli et al.[14] reported that leaks persisting longer than 3 days had an increased need for operative repair, while Yilmazlar et al.[22] found that surgery was required in one-third of patients with delayed leak resolution. Endoscopic and minimally invasive skull base repair techniques have shown excellent closure rates (>90%) and minimal morbidity,[2,3] supporting their early use in patients with anatomically complex fractures.

The role of antibiotic prophylaxis remains controversial. A cochrane review by Ratilal et al.[17] found no significant reduction in meningitis incidence among patients with basilar skull fractures and CSF leaks treated with prophylactic antibiotics, suggesting that antibiotics should not replace definitive closure of dural defects. The current findings therefore align with modern practice favoring early detection and anatomical repair over routine prophylaxis.

The study’s retrospective design and single-center setting inherently limit causal inference and may introduce selection bias. Data abstraction from registry and chart records, while comprehensive, cannot fully account for unmeasured confounders such as leak volume. These constraints mirror those highlighted by Powell et al.,[15] who noted that heterogeneity in fracture classification and management across centers complicates data synthesis. In addition, the small number of CSF leak events (n = 36) may reduce statistical power for the less frequent predictors.

CONCLUSION

Mixed temporal fractures and pneumocephalus are robust predictors of posttraumatic CSF leak, while meningitis and cranial nerve deficits signify higher morbidity and more severe injury patterns. The findings underscore that fracture configuration and radiologic indications are stronger determinants of CSF leak risk than anatomic region alone. Early multidisciplinary assessment and individualized management, balancing conservative therapy with timely surgical repair, remain essential to prevent infection and optimize outcomes.

Ethical approval:

The research/study was approved by the Institutional Review Board at King Abdullah International Medical Research Center (KAIMRC), number NRR26/011/1, dated February 01, 2025.

Declaration of patient consent:

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given consent for clinical information to be reported in the journal. The patient understands that the patient’s names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship:

Nil.

Conflicts of interest:

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation:

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

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