Transorbital sonography and MRI reliability to assess optic nerve sheath diameter in idiopathic intracranial hypertension

Potential of observing the diameter of the optic nerve sheath using computed tomography in diagnosing high intracranial pressure in patients with spontaneous CSF rhinorrhea

KEY POINTS

Spontaneous cerebrospinal fluid rhinorrhea (sCSFR) is often accompanied by an increase in intracranial pressure (ICP). The widening of optic nerve sheath diameter (ONSD) is an indicator of increased ICP. Using CT to measure ONSD is a simple and noninvasive auxiliary method for determining high ICP in sCSFR patients.

Identifying idiopathic intracranial hypertension in a hospital-based chronic headache population: Utility of magnetic resonance imaging, magnetic resonance venography and trans-orbital sonography

BACKGROUND

One of the most underestimated types of chronic headaches is headaches as a result of cerebro-spinal fluid dysregulation disorders. Idiopathic intracranial hypertension (IIH) presents with headache and visual symptoms and usually is associated with papilledema. We identified patients with IIH in a chronic headache population presenting to a hospital-based headache clinic, and studied its associations with clinical, sonographic and magnetic resonance imaging (MRI) findings.

METHODS

Of 168 patients, 141 chronic headache patients were identified and completed the study procedures (semi-structured medical interview, fundus examination, MRI brain with magnetic resonance venography (MRV) and trans-orbital sonography (TOS)). Patients with abnormal findings underwent lumbar puncture for opening pressure.

RESULTS

The prevalence of IIH was 27%. IIH patients were of higher age, had gnawing/throbbing headache in the vertex in most cases, and had higher body mass index. Fundus examination had a sensitivity of 79% and a specificity of 98% for the detection of IIH cases. Approximately 23% of IIH patients had no papilledema. The most sensitive MR sign was found to be transverse sinus stenosis. TOS showed optic nerve sheath dilation in 35.7% of IIH without papilledema cases.

CONCLUSIONS

The prevalence of IIH is high in the chronic headache population and should be suspected in the headache clinic setting, particularly because there is significant overlap with migraine symptomatology. MRI/MR venography and TOS can be useful adjunct tests to identify IIH patients.

Optic nerve sheath diameters in nontraumatic brain injury: A scoping review and role in the intensive care unit

BACKGROUND

Neuromonitoring in medical intensive care units is challenging as most patients are unfit for invasive intracranial pressure (ICP) modalities or unstable to transport for imaging. Ultrasonography-based optic nerve sheath diameter (ONSD) is an attractive option as it is reliable, repeatable and easily performed at the bedside. It has been sufficiently validated in traumatic brain injury (TBI) to be incorporated into the guidelines. However, currently the data for non-TBI patients is inconsistent for a scientific recommendation to be made.

AIM

To compile the existing evidence for understanding the scope of ONSD in measuring ICP in adult non-traumatic neuro-critical patients.

METHODS

PubMed, Google Scholar and research citation analysis databases were searched for studies in adult patients with non-traumatic causes of raised ICP. Studies from 2010 to 2024 in English languages were included.

RESULTS

We found 37 articles relevant to our search. The cutoff for ONSD in predicting ICP varied from 4.1 to 6.3 mm. Most of the articles used cerebrospinal fluid opening pressure followed by raised ICP on computed tomography/magnetic resonance imaging as the comparator parameter. ONSD was also found to be a reliable outcome measure in cases of acute ischaemic stroke, intracerebral bleeding and intracranial infection. However, ONSD is of doubtful utility in septic metabolic encephalopathy, dysnatremias and aneurysmal subarachnoid haemorrhage.

CONCLUSION

ONSD is a useful tool for the diagnosis of raised ICP in non-traumatic neuro-critically ill patients and may also have a role in the prognostication of a subset of patients.

High myopia at high altitudes

Background: Optic nerve sheath diameter (ONSD) increases significantly at high altitudes, and is associated with the presence and severity of acute mountain sickness (AMS). Exposure to hypobaria, hypoxia, and coldness when hiking also impacts intraocular pressure (IOP). To date, little is known about ocular physiological responses in trekkers with myopia at high altitudes. This study aimed to determine changes in the ONSD and IOP between participants with and without high myopia (HM) during hiking and to test whether these changes could predict symptoms of AMS. Methods: Nine participants with HM and 18 without HM participated in a 3-day trek of Xue Mountain. The ONSD, IOP, and questionnaires were examined before and during the trek of Xue Mountain. Results: The ONSD values increased significantly in both HM (p = 0.005) and non-HM trekkers (p = 0.018) at an altitude of 1,700 m. In the HM group, IOP levels were greater than those in the non-HM group (p = 0.034) on the first day of trekking (altitude: 3,150 m). No statistically significant difference was observed between the two groups for the values of ONSD. Fractional changes in ONSD at an altitude of 1,700 m were related to the development of AMS (r pb = 0.448, p = 0.019) and the presence of headache symptoms (r pb = 0.542, p = 0.004). The area under the ROC curve for the diagnostic performance of ONSD fractional changes at an altitude of 1,700 m was 0.859 for predicting the development of AMS and 0.803 for predicting the presence of headache symptoms. Conclusion: Analysis of changes in ONSD at moderate altitude could predict AMS symptoms before an ascent to high altitude. Myopia may impact physiological accommodation at high altitudes, and HM trekkers potentially demonstrate suboptimal regulation of aqueous humor in such environments.

A Novel Nomogram Based on Quantitative MRI and Clinical Features for the Prediction of Neonatal Intracranial Hypertension

Intracranial hypertension (ICH) is a serious threat to the health of neonates. However, early and accurate diagnosis of neonatal intracranial hypertension remains a major challenge in clinical practice. In this study, a predictive model based on quantitative magnetic resonance imaging (MRI) data and clinical parameters was developed to identify neonates with a high risk of ICH. Newborns who were suspected of having intracranial lesions were included in our study. We utilized quantitative MRI to obtain the volumetric data of gray matter, white matter, and cerebrospinal fluid. After the MRI examination, a lumbar puncture was performed. The nomogram was constructed by incorporating the volumetric data and clinical features by multivariable logistic regression. The performance of the nomogram was evaluated by discrimination, calibration curve, and decision curve. Clinical parameters and volumetric quantitative MRI data, including postmenstrual age (p = 0.06), weight (p = 0.02), mode of delivery (p = 0.01), and gray matter volume (p = 0.003), were included in and significantly associated with neonatal intracranial hypertension risk. The nomogram showed satisfactory discrimination, with an area under the curve of 0.761. Our results demonstrated that decision curve analysis had promising clinical utility of the nomogram. The nomogram, incorporating clinical and quantitative MRI features, provided an individualized prediction of neonatal intracranial hypertension risk and facilitated decision making guidance for the early diagnosis and treatment for neonatal ICH. External validation from studies using a larger sample size before implementation in the clinical decision-making process is needed.