Abstract

Background: This study aims to investigate the relationship between optic nerve sheath diameter (ONSD) measurements and clinical outcomes in patients undergoing decompressive craniectomy (DC) due to cerebral infarction. The study evaluated the effect of ONSD on intracranial pressure (ICP) and neurological recovery after DC and determined the prognostic value of this measurement.

Methods: This study was conducted on 54 patients who underwent DC for cerebral infarction between 2018 and 2024 at a tertiary university hospital, Atatürk university faculty of medicine. Demographic data (age, gender), clinical data (preoperative and postoperative Glasgow Coma Scale [GCS] scores, Glasgow Outcome Scale [GOS] scores), and ONSD measurements were obtained from patient records. ONSD measurements were taken at preoperative 1 h, postoperative 1 h, postoperative 24 h, and postoperative 72 h. Measurements were performed with an ultrasound probe on both eyes while patients were in a supine position with their eyes closed. Patients were divided into two groups based on their GCS scores: Group 1 (GCS > 8) and Group 2 (GCS ≤ 8). Statistical analyses of the data were performed using Student’s t-test and Mann–Whitney U-test, with P

Results: Group 1 consisted of 26 patients (mean age 67.2 ± 6.4 years), and Group 2 consisted of 28 patients (mean age 72.4 ± 5.8 years) (P = 0.019). Preoperative ONSD was significantly wider in Group 2 (6.3 ± 0.5 mm) compared to Group 1 (5.2 ± 0.4 mm) (P ≈ 0). Postoperative 1-h ONSD values were also significantly wider in Group 2 (6.0 ± 0.6 mm) compared to Group 1 (4.8 ± 0.5 mm) (P ≈ 0). At 24 and 72 h, ONSD values in Group 2 remained significantly wider compared to Group 1. GOS scores were lower in Group 2 (2.1 ± 0.9) compared to Group 1 (3.2 ± 0.8) (P ≈ 0). There was a strong negative correlation between ONSD measurements and GOS scores.

Conclusion: ONSD is an important non-invasive indicator in the assessment of ICP and clinical outcomes. High ONSD values are associated with poor clinical outcomes, and a reduction in postoperative ONSD reflects the success of surgical intervention. ONSD measurements can be used as a prognostic tool in clinical practice and play a crucial role in the management and monitoring of patients with high ICP. It is recommended that these findings be validated in larger patient groups and different clinical scenarios.

Keywords: Cerebral infarction, Decompressive craniectomy, Intracranial pressure, Optic nerve sheath diameter, Prognostic indicator

INTRODUCTION

Stroke is a major cause of death and disability worldwide and is a challenging pathological condition involving various medical disciplines in its management.[ 7 , 12 ] Malignant ischemic stroke is characterized by progressive edema, increased intracranial pressure (ICP), and neurological deterioration due to cerebral herniation.[ 11 ] Despite aggressive treatment, the mortality rates of this rapidly progressing condition are quite high.[ 2 , 9 ] Intracranial hypertension is defined as cerebrospinal fluid pressure of ≥20 mm Hg, and the gold standard method for measuring ICP involves the placement of an invasive intraparenchymal probe or intraventricular catheter.[ 20 ] However, due to its cost, potential infections, and increased risk of bleeding, it is neither suitable nor practical.[ 3 , 6 ] In contrast, measuring optic nerve sheath diameter (ONSD) via ocular ultrasonography for ICP monitoring is a noninvasive and cost-effective method reported to be more sensitive and specific than invasive techniques.[ 4 , 6 , 14 ] One of the treatment methods for resistant intracranial hypertension, which has high morbidity and mortality rates and is equally challenging to treat, is decompressive craniectomy (DC). DC is a surgical technique that provides space for the increased parenchymal volume by removing the non-expandable skull in resistant cases. Although there is no complete consensus in the literature on the indications, timing, and outcomes of DC, it holds a significant place in treatment.[ 13 , 21 , 23 ] Postoperative patient monitoring after DC is crucial for evaluating the effectiveness of the surgery and early detection of potential complications. ONSD measurements emerge as a significant tool in assessing increased ICP as a non-invasive method. It is widely documented in the literature that ONSD is associated with increased ICP and that this measurement can aid in monitoring neurological status.[ 1 , 6 , 8 , 16 , 18 ]

In light of this information, this study investigated the relationship between ONSD measurements and clinical outcomes in patients with cerebral infarction who underwent DC. The study aims to evaluate the effect of ONSD on ICP and neurological recovery after DC and to determine the prognostic value of this measurement. Accordingly, the relationships between preoperative and postoperative ONSD values and clinical outcomes were examined.

MATERIALS AND METHODS

This study was conducted on 54 patients who underwent DC for cerebral infarction between 2018 and 2024 at a tertiary university hospital, Atatürk university faculty of medicine. Demographic data (age, gender), clinical data (preoperative and postoperative Glasgow Coma Scale [GCS] scores, Glasgow Outcome Scale [GOS] scores), and ONSD measurements were obtained from patient records. ONSD measurements were recorded at preoperative 1 h, postoperative 1 h, postoperative 24 h, and postoperative 72 h. ONSD measurements were taken from both eyes while the patient was in a supine position with eyes closed. The ultrasound probe was gently placed on the eyelids with sterile gel, and ONSD, appearing as a hypoechoic band approximately 3 mm behind the globe, was measured metrically. Measurements were taken for each eye, and the average value was calculated. Subsequently, the patients in the study were divided into two groups based on their GCS scores: Group 1 (GCS >8) and Group 2 (GCS ≤8). Demographic and clinical data were statistically compared between the groups.

All data were analyzed using IBM Statistical Package for the Social Sciences Version 25.0. Descriptive statistics (mean, standard deviation, and percentage) of demographic and clinical data were calculated. Student’s t-test and Mann– Whitney U-test were used for comparisons between groups. The t-test was used to evaluate the changes in preoperative and postoperative ONSD values over time. P < 0.05 was considered statistically significant.

RESULTS

According to preoperative GCS values, there were 26 patients in Group 1 and 28 patients in Group 2. In Group 1, 11 patients were male and 15 were female, while in Group 2, there were 13 males and 15 females. The average age of patients with GCS > 8 was 67.2 ± 6.4 years, whereas the average age of patients with GCS ≤ 8 was 72.4 ± 5.8 years. This difference was statistically significant (P = 0.019), indicating that patients with GCS ≤ 8 were generally older. This finding suggests that age is an important factor affecting clinical status after cerebral infarction. The average preoperative GCS value for patients in Group 1 was 10.1 ± 1.2, while the average for patients in Group 2 was 5.3 ± 1.2. The average postoperative 24-h GCS value for patients in Group 1 was 11.2 ± 1.7, whereas it was 4.6 ± 1.5 for patients in Group 2. This difference was also statistically significant (P ≈ 0), indicating that patients with GCS ≤8 had worse clinical conditions in the postoperative period.

The average preoperative 1-h ONSD value was 5.2 ± 0.4 mm for patients with GCS >8, while it was 6.3 ± 0.5 mm for patients with GCS ≤8 (P ≈ 0). This result indicates that preoperative ONSD was wider in patients with GCS ≤8. Preoperative wide ONSD can be considered an indicator of increased ICP. The average postoperative 1-h ONSD was 4.8 ± 0.5 mm for patients with GCS >8 and 6.0 ± 0.6 mm for patients with GCS ≤8 (P ≈ 0). This difference shows that ONSD remained wider in patients with GCS ≤8, even in the postoperative period. This may indicate that ICP was not sufficiently reduced in some patients immediately after the surgical intervention.

The average postoperative 24-h ONSD was 4.5 ± 0.6 mm for patients with GCS >8 and 5.8 ± 0.7 mm for patients with GCS ≤8 (P ≈ 0). This result shows that ONSD was still wider in patients with GCS ≤8 at postoperative 24 h. The decrease in ONSD within the 1^st 24 h can indicate the effectiveness of the surgical intervention and the reduction of brain edema. The average postoperative 72-h ONSD was 4.2 ± 0.6 mm for patients with GCS >8 and 5.5 ± 0.8 mm for patients with GCS ≤8 (P ≈ 0) [ Table 1 ]. This difference shows that ONSD remained wider in patients with GCS ≤8 at postoperative 72 h as well. This finding suggests that ONSD can be used as an indicator of clinical status in the long term.

Table 1:

Characteristics and mean values of the groups.

There was no significant difference in ONSD measurements between the right and left sides where decompression was performed (P > 0.05). This result indicates that the effect of the surgical intervention was similar regardless of the side.

For all patients, ONSD values decreased from 5.75 mm preoperatively to 4.50 mm at postoperative 72 h. This change demonstrates the effect of the surgical intervention and the reduction in ICP. In Group 1, ONSD values decreased from 5.2 mm preoperatively to 4.2 mm at postoperative 72 h. In Group 2, ONSD values decreased from 6.3 mm preoperatively to 5.5 mm at postoperative 72 h. This shows that even in patients with worse clinical outcomes, ONSD decreased over time but remained higher [ Table 2 ].

Table 2:

ONSD values and changes over time.

GOS scores were used to evaluate clinical outcomes. There were significant differences in GOS scores between patients with GCS >8 and those with GCS ≤8. GOS scores were 3.2 ± 0.8 in patients with GCS >8 and 2.1 ± 0.9 in patients with GCS ≤8 (P ≈ 0). These results indicate that clinical outcomes were better in patients with GCS >8. The relationship between GOS scores and ONSD measurements was also evaluated. There was a strong negative correlation between preoperative 1-h ONSD averages and GOS scores (r = − 0.72, P ≈ 0). Similarly, significant negative correlations were found between postoperative 1-h (r = − 0.68, P ≈ 0), 24-h (r = − 0.65, P ≈ 0), and 72-h (r = − 0.63, P ≈ 0) ONSD averages and GOS scores [ Table 3 ]. These findings indicate that patients with higher ONSD had worse clinical outcomes. This correlation suggests that ONSD can be used to predict clinical outcomes.

Table 3:

Correlation between ONSD values and GOS.

Nineteen patients died within the 1^st 72 h postoperatively. Of these patients, six were in Group 1 and 13 were in Group 2. The ONSD values of these patients were compared with those of the surviving patients. The preoperative ONSD measurements of the deceased patients were 6.5 ± 0.5 mm and decreased to 6.2 ± 0.8 mm at postoperative 72 h. In the surviving patients, the preoperative ONSD was 5.7 ± 0.5 mm and decreased to 4.4 ± 0.8 mm at 72 h. There was no significant change in ONSD values in the deceased patients during the postoperative period (P = 0.80) [ Table 4 ]. This may indicate that the surgical intervention did not sufficiently reduce ICP and reflects a poor prognosis. In the surviving patients, a significant decrease in ONSD values was observed (P = 0.0054). This shows the effectiveness of the surgical intervention and the reduction in pressure.

Table 4:

ONSD Values for deceased and surviving patients.

DISCUSSION

Cerebral infarction remains a complex medical condition involving surgical and internal branches and is a significant cause of morbidity and mortality.[ 5 ] It is known that performing DC can prevent the devastating stages of intracranial hypertension and significantly affect the overall outcomes of these patients.[ 12 , 15 ] Although there is no clear consensus on the timing of surgical intervention, there are publications suggesting that intervention within the first 6 h can increase the benefits seen.[ 10 , 25 ] To observe the effectiveness of this intervention aimed at reducing increased ICP, both the patient’s clinical condition and ICP must be monitored in the early and late periods. One of the noninvasive and effective methods for ICP monitoring is ONSD measurement.[ 4 , 6 , 14 ]

Current studies have shown that increased ONSD is associated with high ICP and that this condition leads to poor neurological outcomes. There are publications in the literature regarding the usability of ONSD as a noninvasive indicator of ICP.[ 6 , 8 , 14 , 18 , 19 , 26 ] Our findings support these results, showing that ONSD is wider in patients with GCS ≤8 in both preoperative and postoperative periods. This suggests that high ICP is more pronounced in these patients and is not sufficiently reduced despite surgical intervention.

Changes in ONSD measurements provide important information in evaluating the effectiveness of surgical intervention. Postoperative 72-h ONSD measurements were found to be 4.2 ± 0.6 mm in patients with GCS >8 and 5.5 ± 0.8 mm in patients with GCS ≤8. This difference indicates that ONSD can be used to evaluate the long-term effectiveness of surgical intervention. Specifically, the negative correlation between GOS scores and ONSD measurements (preoperative r = − 0.72, postoperative 1-h r = − 0.68, postoperative 24-h r = − 0.65, postoperative 72-h r = −0.63) shows that high ONSD values are associated with poor clinical outcomes. These findings suggest, as previously mentioned in the literature, that ONSD can be used as a prognostic tool.[ 17 ]

Monitoring patients after surgical intervention is critical for evaluating the effectiveness of the surgery and detecting potential complications early. ONSD measurements stand out as an important tool in assessing increased ICP as a non-invasive method. There are studies in the literature examining the effectiveness of ONSD measurements in controlling ICP after DC. The literature reports that ONSD shows high sensitivity and specificity in detecting increased ICP.[ 6 , 18 , 22 , 24 ] These findings are consistent with our study and support that ONSD can be used to control ICP after surgical intervention.

The wider preoperative ONSD indicates that patients had high ICP before the surgical intervention. This suggests that preoperative ONSD measurements can be used to determine the need for surgical intervention. In addition, the decrease in ONSD over time in the postoperative period shows the effectiveness of the surgical intervention and the reduction of brain edema. However, the insufficient reduction of ONSD in patients with GCS ≤8 despite surgical intervention indicates that these patients are at higher risk and require more intensive monitoring.

The non-invasive and easy applicability of ONSD measurements makes this method widely usable in clinical practice. Particularly in intensive care units and emergency departments, ONSD measurements can be used quickly and reliably to detect increased ICP. This provides a significant advantage in determining the need for early intervention in high-risk patients.

This study has some limitations. Patients were evaluated based on preoperative, postoperative, and GOS values. Since the preoperative and postoperative vital parameters of the patients were not recorded, their impact on ICP was not investigated. In addition, the specific effects of anti-edema treatment (name of the edema drug, ventilation rate, and head elevation status) on patients were not included in the study.

Availability of data and materials

Data supporting the findings of this study are available from the corresponding author upon reasonable request.

Code availability

It is not applicable, as no custom software or code was necessary for the analysis presented in this study.

Consent to participate

Not applicable. This study did not involve direct interaction with patients or changes to patient care, and it relied on the analysis of anonymized data, for which patient consent was waived.

Consent for publication

All authors confirm that this manuscript is an original submission, has not been published elsewhere in any form, and has not been submitted to any other publication for review. Each author has agreed to be accountable for all aspects of the work.

CONCLUSION

Our study shows that ONSD measurements can play an important role in the follow-up of patients undergoing DC after cerebral infarction. High ONSD values can be considered indicators of increased ICP and poor clinical outcomes. Therefore, it can be suggested that ONSD be used as a prognostic indicator in routine clinical practice. The decrease in ONSD in surviving patients shows that the surgery was effective and contributed to the recovery process. In addition, the use of ONSD can serve as an important tool in clinical decision-making processes. For example, increased ONSD values can alert clinicians to situations requiring early intervention, allowing closer monitoring of patients. ONSD measurements can also be used to evaluate the effectiveness of surgical interventions. The decrease in ONSD after surgery can be considered an indicator of successful decompression.

In the future, validating ONSD measurements in larger patient groups and different clinical scenarios will enhance the reliability of this method. In addition, the combined use of ONSD with different surgical and medical treatment methods should be investigated, and the effectiveness of this method in predicting clinical outcomes should be examined in more detail.

Ethical approval:

Institutional review board (IRB) / Institutitional Ethics Committee (IEC)permission is not required as it is retrospective study. The study adhered to the ethical standards of the Institutional and/or National Research Committee, and was in accordance with the 1964 Helsinki declaration and its later amendments.

Declaration of patient consent:

Patient’s consent not required as patients identity is not disclosed or compromised.

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 ıntelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

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