B-mode transorbital ultrasonography for the diagnosis of idiopathic intracranial hypertension: an updated systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis aimed to evaluate the role of B-mode transorbital ultrasonography (TOS) for the diagnosis of idiopathic intracranial hypertension (IIH) in adults.

METHODS

MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) (1966-May 2022) were searched to identify studies reporting ultrasonographic data about the optic nerve sheath diameter (ONSD) and optic disc elevation (ODE) in adults with IIH compared to subjects without IIH. The quality of the included studies was evaluated by the Newcastle-Ottawa Quality.

RESULTS

Fifteen studies were included (total of 439 patients). The values of ODE ranged from 0.6 to 1.3 mm in patients with IIH. The values of ONSD ranged from 4.7 to 6.8 mm in IIH patients and from 3.9 to 5.7 mm in controls. In IIH patients, the ONSD was significantly higher compared to controls (standardized mean difference: 2.5 mm, 95% confidence interval (CI): 1.6-3.4 mm). Nine studies provided data about the presence of papilledema and the pooled prevalence was 95% (95% CI, 92-97%).

CONCLUSIONS

In adults, the thickness of ONSD and the entity of ODE were significantly associated with IIH. B-mode TOS enables to noninvasively detect increased ICP and should be performed, potentially routinely, in any patient with suspected IIH.

Optic nerve sheath diameter: present and future perspectives for neurologists and critical care physicians

BACKGROUND

Estimation of intracranial pressure (ICP) may be helpful in the management of neurological critically ill patients. It has been shown that ultrasonography of the optic nerve sheath diameter (ONSD) is a reliable tool for non-invasive estimation of increased intracranial pressure (ICP) at hospital admission or in intensive care. Less is known about the estimation of increased ICP and usefulness of ONSD in the prehospital setting. The aim of this review was to elucidate both prevailing and novel applications of ONSD for neurologists and critical care physicians.

METHODS

In this review, we discuss the technique and the novel approach of ONSD measurement, the clinical applications of ONSD in neurology and critical care patients.

RESULTS

ONSD measurement is simple, easy to learn, and has diverse applications. ONSD has utility for ICP measurement in intracranial hemorrhage and ischemic stroke, meningitis and encephalitis, and idiopathic intracranial hypertension (IIH). It is also valuable for lesser known syndromes, where an increase of ICP is postulated, such as acute mountain sickness and posterior reversible encephalopathy syndrome. ONSD changes develop in inflammatory or ischemic optic neuropathies. Some papers demonstrate the usefulness of ONSD studies in symptomatic intracranial hypotension.

CONCLUSIONS

ONSD is a safe and low-cost bedside tool with the potential of screening patients who need other neuroimaging and those who may need an invasive measurement of ICP.

The Importance of Optic Nerve Sheath Diameter in Post-dural Puncture Headache Diagnosis and Follow-up

Introduction

Intracranial hypotension-induced headache is caused by reduction in the volume or pressure of the cerebrospinal fluid. Headache might develop secondary to lumbar puncture. In the detection of intracranial hypotension, when compared with invasive methods, there is a good correlation between ultrasound-guided optic nerve sheath diameter (ONSD) and invasive methods. The aim of the study is to investigate the effectiveness of alteration in ultrasound-guided ONSD in diagnosis and treatment of post-dural puncture headache (PDPH) induced by intracranial hypotension.

Methods

Our study involved 40 adult patients aged 18-65 scheduled to have surgery under spinal anesthesia. Patients were randomized into two groups consisting of PDPH (Group H, n=20), and control (Group C, n=20) during their post-operative period. The ONSDs of patients were measured via ultrasound, pain severity with Numeric Rating Scale (NRS) pre-operatively, at 24^th, 26^th and 48^th hours post-operatively. Conservative treatment was started on the 24^th hour in PDPH group.

Results

There was no significant difference between the groups in terms of demographic data. In Group H, the reduction in ONSD from 3.8±0.2 to 3.2±0.3 mm in postoperative 24^th hours (p=0.001) and an increase to 4.4±0.3 mm in postoperative 48^th hours (p=0.03) were significant. When compared to postoperative 24^th hours, ONSD in postoperative 26^th (3.9±0.3 mm) and 48^th hours (4.4±0.3 mm) were significantly higher (p=0.007 and p=0.01; respectively) in Group H. NRS values in Group H at postoperative 26^th and 48^th hours were significantly lower compared to postoperative 24^th hours (p=0.001).

Conclusion

We believe that serial measurement of ultrasound-guided ONSD, which is considered a simple and non-invasive procedure in the determination of intracranial pressure changes, is a more objective method in the follow-up of intracranial hypotension-induced headache compared to NRS evaluation.