Evaluating the optic nerve stiffness and optic nerve sheath diameter in idiopathic intracranial hypertension patients after the resolution of papilledema

A prospective observational study on intracranial pressure management: A comparison of three ultrasound techniques

OBJECTIVE

This prospective observational study aimed to assess the effectiveness of B-mode ultrasound, color-coded Doppler, and shear-wave elastography in predicting intracranial pressure (ICP) and their capability to evaluate the efficacy of ICP lowering therapy.

MATERIALS AND METHODS

Forty-eight neuro-critical care patients were enrolled and categorized into 2 groups based on ICP measurements obtained through external ventricular drainage: the intracranial hypertension (IH) and normal ICP groups. The optic nerve (ON) sheath diameter (ONSD), end diastolic velocity, peak systolic velocity, resistance index of the central retinal artery (CRA), and Young's modulus (YM) of the ON were recorded after external ventricular drainage placement and following ICP lowering treatment in the IH group.

RESULTS

The median values of ONSD (5.35 mm [IQR 5.03, 5.80 mm] vs. 4.38 mm [IQR 4.25, 4.60 mm]) and YM of the ON (23.69 kPa [IQR 18.83, 30.90 kPa] vs. 10.48 kPa [IQR 9.84, 12.41 kPa]) were remarkably higher in the IH group than in the normal ICP group (both P < 0.001). However, no obvious differences were observed in end diastolic velocity, peak systolic velocity, or resistance index of the CRA between the two groups (all P > 0.05). Additionally, analysis of the differences in ultrasound parameters before and after treatment revealed that ΔYM of the ON exhibited higher sensitivity and specificity in detecting successful treatment of IH compared to ΔONSD.

CONCLUSION

ΔYM of the ON may serve as a more valuable parameter for reflecting changes in ICP and predicting the efficacy of treatment. In contrast, the color-coded Doppler indices of the CRA had limited values in evaluating ICP.

Correlation between optic nerve sheath diameter measured by bedside ultrasound and intracranial pressure in neurologically ill patients in a Chinese population

BACKGROUND

We assessed the correlation between optic nerve sheath diameter (ONSD) values measured by bedside ultrasound and intracranial pressure (ICP) changes among patients under neurocritical care and evaluated the diagnostic performance of ONSD for increased ICP.

METHODS

Sixty-seven neurologically critical patients who were hospitalised in the intensive care unit (ICU) of Jining No.1 People's Hospital between September 2023 and March 2024 and underwent lumbar puncture were included. The ONSD was measured and recorded using bedside ultrasound before the lumbar puncture. Patients were divided into normal and increased ICP groups on the basis of the initial lumbar puncture pressure on admission, and both groups were compared. Spearman's correlation analysis was used for evaluating the correlation between ONSD values and ICP. Receiver operating characteristic (ROC) curves were employed for evaluating the diagnostic performance of ONSD for increased ICP.

RESULT

At admission, the Glasgow Coma Scale scores of patients in the increased ICP group were significantly lower than those of patients in the normal ICP group (P < 0.05). The ONSD level of patients in the increased ICP group was significantly higher than that of patients in the normal ICP group (P < 0.05). Spearman's correlation analysis revealed that ONSD positively correlated with ICP among patients with severe neurological diseases (r = 0.777, P < 0.001). The area under the ROC curve when using ONSD for diagnosing lumbar puncture opening pressure ≥ 200 mmH2O was 0.896 (95% confidence interval, 0.817-0.974). When using ONSD ≥ 4.74 mm as the threshold for diagnosing lumbar puncture opening pressure ≥ 200 mmH2O, the sensitivity and specificity were 0.909 and 0.765, respectively.

CONCLUSION

In patients with critical neurological illness, ONSD measured using bedside ultrasound positively correlated with ICP. Increased ICP can be diagnosed for ONSD ≥ 4.74 mm. The ONSD value measured by bedside ultrasound can be used for evaluating ICP among patients with critical neurological illness.

Shear-wave elastographic imaging in choroidal melanomas: clinical and hemodynamic correlations

PURPOSE

This study evaluated the role of shear wave elastography imaging (SWEΙ) in uveal melanomas and the associations between SWEI and clinical and hemodynamic findings.

STUDY DESIGN

Prospective, clinical study METHODS: Twelve patients with uveal melanomas, scheduled to undergo Ru-106 brachytherapy, were prospectively recruited from the Department of Ophthalmology of the University Hospital of Heraklion (September-December 2022). B-mode, hemodynamic and SWEI ultrasonography examinations were performed with the HiScan (OPTIKON 2000) and the LOGIQ E9 (GE Healthcare) sonographic systems, respectively. Differences in SWEI scores (kPa) between tumor (TS) and adjacent non-affected choroid (CS), as well as between TS and orbital fat (FS) were examined. Correlations between SWEI and intra-tumoral hemodynamic parameters, including peak systolic and end diastolic velocities and resistivity index (RI) were also examined.

RESULTS

TS was significantly correlated with intra-tumoral RI (Pearson's bivariate correlation coefficient 0.681, p=0.015) and with maximal tumor height (Pearson's bivariate correlation coefficient 0.620, p=0.031). TS was significantly higher than both FS and CS scores (paired-samples t-test, p=0.003 and p=0.006, respectively).

CONCLUSIONS

SWEI score is applicable as a quantitative biomechanical marker in the assessment of choroidal melanoma. Choroidal melanomas are stiffer than both adjacent choroid and orbital fat. Moreover, choroidal melanomas with higher RI as well as those with higher apical elevations display higher SWEI scores.

Higher cerebrospinal fluid (CSF) opening pressure in patients with idiopatic intracranial hypertension (IIH) with permanent visual impairment

Objective The aim of this study was to identify potential visual prognostic markers in patients with idiopathic intracranial hypertension (IIH).  Methods Patients with IIH of an outpatient headache clinic in São Paulo, Brazil, were retrospectively evaluated and divided in two groups with and without the presence of permanent visual deficit attributed to IIH. Body mass index (BMI), opening CSF pressure, and the frequency of IIH related MRI abnormalities were compared between these two groups.  Results Twenty-nine patients, with 35,39±9,93 years, being twenty-eight female (96.55%) were included in the study. Reduced visual acuity attributed to IIH was registered in 16 (55.17%). According to BMI 17.4% had overweight and 82.6% were obese. Brain MRI was normal in 6 (20.69%). BMI, obesity, and the presence of MRI abnormalities were not associated with visual impairment. Initial CSF opening pressure was significantly higher in the group of patients with reduced visual acuity (40.4±13.14 x 30.5±3.41, P=0,015).  Conclusion Higher CSF opening pressure at onset was significantly associated with a higher percentage of visual impairment in patients with IIH suggesting this measure as a potential prognostic marker for patients with IIH.  

Non-invasive intracranial pressure assessment using shear-wave elastography in neuro-critical care patients

OBJECTIVE

To determine if Young's modulus of the optic nerve (ON) structure as measured by shear-wave elastography can suggest changes in intracranial pressure (ICP) in neuro-critical care patients.

MATERIALS AND METHODS

Thirty-one healthy volunteers and twenty-two neuro-critical care patients were enrolled. ON sheath (ONS) diameter (ONSD) values and Young's modulus measurements of volunteers were collected in a calm state and during a Valsalva maneuver (VM). Ultrasound measurements and ICP values of patients were collected on operation day and at 24 and 48 h after the operation; measurements were thereafter assigned to three groups: severely elevated (ICP greater than 22 mmHg), mildly elevated (ICP = 14-22 mmHg), and normal (ICP ≤ 13 mmHg).

RESULTS

ONSD and Young's modulus for the ON and ONS of volunteers during VM were higher than those in the calm state (all P < 0.001). In contrast to ONSD, Young's modulus for ON and ONS did not correlate with age, body mass index, or sex. The best cutoff values of Young's modulus for ON for predicting elevated and severely elevated ICP were 16.67 kPa and 22.74 kPa, respectively. Accordingly, the sensitivity values were 96.7% and 88.9%, and the specificity values were 86.1% and 73.7%, which had the same diagnostic performance as ONSD.

CONCLUSION

Young's modulus of the ON accurately reflects changes in ICP. It is not confounded by age, sex, or body mass index compared to ONSD.

Assessment of peripapillary choroidal thicknesses and optic disc diameters in idiopathic intracranial hypertension

OBJECTIVE

To evaluate the peripapillary choroidal thickness and optic disc diameter changes in the eyes of patients who had idiopathic intracranial hypertension (IIH) when they had swollen discs and after resolution of the papilledema.

DESIGN

This is an observational, cross-sectional study. Optical coherence tomography was performed on both eyes of patients with IIH, who had been divided into 2 groups: 18 patients with acute papilledema and 25 patients with resolved papilledema. Twenty healthy participants were also enrolled in this study.

METHODS

In this observational, cross-sectional study, the thickness of the retinal nerve fibre layer, the peripapillary choroidal thickness (PCT), the ganglion cell complex thickness, and the optic disc diameters were measured using optical coherence tomography.

RESULTS

In the resolved-papilledema subgroup, PCT in all quadrants was significantly lower than in the control group (p < 0.001 for each). In the acute-papilledema subgroup, PCT in the temporal, inferior, and superior quadrants was significantly less than in the control eyes (p < 0.001, p = 0.003, p = 0.049, respectively). The disc diameters in the vertical and horizontal planes were also significantly larger in the acute-papilledema eyes than in the control eyes and in the resolved papilledema eyes (p < 0.001 for each).

CONCLUSION

PCT decreases both at the acute and chronic stages of IIH, and optic disc diameter increases in patients with IIH who have swollen discs.

Effect of changes in optic nerve elasticity on central retinal artery blood flow in patients with idiopathic intracranial hypertension

PURPOSE

To assess changes in central retinal artery (CRA) blood flow by orbital color-coded Doppler ultrasonography in patients with idiopathic intracranial hypertension (IIH) and their relation with optic nerve (ON) elasticity assessed by shear wave elastography (SWE).

METHODS

This study was carried out on 68 eyes of patients diagnosed with IIH and 32 eyes of healthy controls. The severity of papilledema in IIH patients was sub-classified into mild and moderate/severe groups. Color-coded Doppler was used to measure peak systolic velocity (PSV), end diastolic velocity (EDV), mean velocity (V_mean) and pulsatility index (PI) of the CRA.

RESULTS

PSV, V_mean, and SWE were significantly higher in patients with IIH than in controls (p = 0.001). The optimal cut-off values of PSV and V_mean for differentiating IIH patients from controls were 11.25 and 6.75 cm/s with AUC 0.81 and 0.785 respectively. AUC was 0.92 and accuracy 91% for combined PSV, V_mean and SWE differentiation between IIH patients and controls. PSV, V_mean and SWE were significantly different between mild versus moderate/severe papilledema (p = 0.001). PSV and V_mean were correlated with papilledema (r = 0.790 and 0.722 respectively) and SWE (r = 0.818 and 0.761 respectively).

CONCLUSION

IIH is associated with decreased ON elasticity and reduced CRA blood flow. Individual and combined color-coded Doppler of the CRA and SWE help in diagnosis of IIH. CRA hemodynamic changes are correlated with papilledema severity and with the extent of biomechanical changes in the ON represented by SWE.