Diameter of the optic nerve in idiopathic optic neuritis and in anterior ischemic optic neuropathy

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.

[Papilledema with visual loss]

SERIAL CASE REPORTS OF THREE MEN WITH PAPILLEDEMA AND VISUAL LOSS: The patients developed primarily visual loss on one or both sides with angiographically and clinically diagnosed papilledema. The neurological and internistic examinations were unsuspicious; however, serology ultimately confirmed the suspected papillitis in acute syphilis.

CONCLUSION

Papillitis with visual loss can be a symptom of syphilis. Not only the known placoid chorioretinitis syphilis has to be considered but also a detailed medical history and diagnostic measures are essential to determine the cause. The guiding principle is usually also the relatively young age of the patients, male gender, sexual orientation and the lack of classic risk factors for anterior ischemic optic neuropathy (AION) or neurological causes of blurred edge swollen papilla as an intracranial mass lesion (papilledema).

[Optic disc swelling : A compilation of relevant differential diagnoses]

Optic disc oedema describes blurred optic disc margins. It describes an unspecific clinical sign with various possible underlying causal mechanisms. The correct diagnosis and the detection of the underlying disease is however of special clinical importance. This article summarizes the most important differential diagnoses and gives advice to find the correct diagnosis.

Constructing a statistical atlas of the radii of the optic nerve and cerebrospinal fluid sheath in young healthy adults

Optic neuritis is a sudden inflammation of the optic nerve (ON) and is marked by pain on eye movement, and visual symptoms such as a decrease in visual acuity, color vision, contrast and visual field defects. The ON is closely linked with multiple sclerosis (MS) and patients have a 50% chance of developing MS within 15 years. Recent advances in multi-atlas segmentation methods have omitted volumetric assessment. In the past, measuring the size of the ON has been done by hand. We utilize a new method of automatically segmenting the ON to measure the radii of both the ON and surrounding cerebrospinal fluid (CSF) sheath to develop a normative distribution of healthy young adults. We examine this distribution for any trends and find that ON and CSF sheath radii do not vary between 20-35 years of age and between sexes. We evaluate how six patients suffering from optic neuropathy compare to this distribution of controls. We find that of these six patients, five of them qualitatively differ from the normative distribution which suggests this technique could be used in the future to distinguish between optic neuritis patients and healthy controls.

Transorbital sonography in acute optic neuritis: a case-control study

BACKGROUND AND PURPOSE

Acute unilateral optic neuritis is associated with a thickening of the retrobulbar portion of the optic nerve as revealed by transorbital sonography, but no comparison has been made between nerve sheath diameter and optic nerve diameter in patients with acute optic neuritis versus healthy controls. We evaluated optic nerve sheath diameter and optic nerve diameter in patients with acute optic neuritis and healthy controls and compared optic nerve sheath diameter and optic nerve diameter with visual-evoked potentials in patients.

MATERIALS AND METHODS

A case-control study was performed in 2 centers. Twenty-one consecutive patients with onset of visual loss during the prior 10 days and established acute noncompressive unilateral optic neuritis were compared with 21 healthy controls, matched for sex and age (±5 years). Two experienced vascular sonographers performed the study by using B-mode transorbital sonography. Visual-evoked potentials were performed on the same day as the transorbital sonography and were evaluated by an expert neurophysiologist. Sonographers and the neurophysiologist were blinded to the status of the patient or control and to clinical information, including the side of the affected eye.

RESULTS

The median optic nerve sheath diameter was thicker on the affected side (6.3 mm; interquartile range, 5.9-7.2 mm) compared with the nonaffected side (5.5 mm; interquartile range, 5.1-6.2 mm; P < .0001) and controls (5.2 mm; interquartile range, 4.8-5.5 mm; P < .0001). The median optic nerve diameter was 3.0 mm (range, 2.8-3.1 mm) on the affected side and 2.9 mm (range, 2.8-3.1 mm) on the nonaffected side (P = not significant.). Both sides were thicker than those in controls (2.7 mm; interquartile range, 2.5-2.8 mm; P = .001 and .009). No correlation was found between optic nerve sheath diameter and optic nerve diameter and amplitude and latency of visual-evoked potentials in patients with optic neuritis.

CONCLUSIONS

Transorbital sonography is a promising tool to support the clinical diagnosis of acute optic neuritis. Further studies are needed to define its specific role in the diagnosis and follow-up of optic neuritis.

Ultrasonography in distinguishing optic neuritis from nonarteritic anterior ischemic optic neuropathy

Background and Objectives:

Optic neuritis (ON) and nonarteritic anterior ischemic optic neuropathy (NAION) have some overlapping clinical profiles. We evaluated the usefulness of B-scan ultrasonography in distinguishing ON from NAION by measuring diameter of the optic nerve.

Materials and Methods:

Consecutive patients with an acute noncompressive unilateral optic neuropathy with relative afferent pupillary defect and onset of visual loss during the last 2 weeks were included. Diagnosis of ON was based on age ≤ 35 years, orbital pain associated with eye movement, and no disk edema, and diagnosis of NAION was based on age ≥ 60 years, no orbital pain associated with eye movement, and presence of disk edema. Age- and gender-matched subjects without ocular disease were selected for comparison. The diameter of the optic nerve was measured by a single radiologist with B-scan ultrasonography.

Results:

In ON patients, the mean diameter of the affected nerve was significantly larger than that of the unaffected nerve and also larger than that of the right nerve of young controls; P < 0.05. In NAION patients, however, there was no significant difference between the mean diameter of the affected nerve and of the unaffected nerve or the right nerve of elderly controls; P > 0.05. Also, the diameter of the affected nerve was significantly larger in ON than in AION patients; P < 0.05.

Conclusion:

B-scan ultrasonography is helpful in the early stages of optic neuropathy to distinguish ON from NAION in those cases for which the diagnosis is still uncertain after clinical evaluation.

Orbital Doppler evaluation of blood flow velocities in optic neuritis

Purpose

To evaluate orbital blood flow velocities and optic nerve diameter with Doppler and gray-scale sonography in patients with acute unilateral optic neuritis (ON).

Methods

Orbital Doppler and gray-scale sonography was performed in 46 eyes of 23 patients aged 19- to 47-years with acute unilateral ON. ON was diagnosed by an ophthalmologist on the basis of clinical presentation, presence of decreased visual acuity and assessment of visual evoked potentials. The peak systolic velocity (PSV) and end-diastolic velocity (EDV), as well as the resistance index (RI) and pulsatile index (PI) of the ophthalmic artery (OA), central retinal artery (CRA), posterior ciliary arteries (PCAs) and optic nerve diameter were measured in both eyes. We compared results from affected and unaffected eyes using the paired t-test. The area under the receiver operating characteristic (ROC) curves was used to assess the diagnosis of ON based on measured blood flow parameters of the OA, CRA and PCAs and optic nerve diameter.

Results

The mean (standard deviation) optic nerve diameter in eyes with ON was 4.1 (0.8) mm, which was significantly larger than the 3.0 (0.4) mm diameter measured in unaffected control eyes (p < 0.001). There were no differences in average PSV, EDV, RI, or PI of the OA and CRA between affected and unaffected eyes (p > 0.05). The mean RI in the PCAs was slightly lower in the eyes with ON than in the contralateral eyes (0.60 vs. 0.64, p < 0.05). The area under the ROC curves indicated that optic nerve diameter was the best parameter for the diagnosis of ON.

Conclusions

Optic nerve diameter was related to ON, but orbital blood flow parameters were not.

Colour Doppler imaging evaluation of blood flow parameters in the ophthalmic artery in acute and chronic phases of optic neuritis in multiple sclerosis

PURPOSE

Optic neuritis (ON) is a common manifestation of multiple sclerosis (MS). It is caused by the immune-mediated inflammation of the optic nerve. Some vascular factors that may influence blood flow in the ophthalmic artery (OA) have also been suggested as factors in the pathogenesis of ON. The purpose of our study was to evaluate blood flow velocities and resistance (RI) and pulsatile (PI) indices in the OA in both orbits in patients in the acute and chronic phases of unilateral ON and to compare these with equivalent findings in healthy control subjects.

METHODS

Orbital colour Doppler imaging (CDI) was performed in 40 consecutive MS patients during acute unilateral ON prior to corticosteroid treatment. Optic neuritis was diagnosed on the basis of clinical presentation and facultative assessment of visual evoked potentials (VEPs). The peak systolic (PSV) and end-diastolic (EDV) velocities and RI and PI were measured in the OA in both eyes. We compared results from affected and unaffected orbits using the paired t-test. The same measurements were performed in 114 MS patients with a history of acute unilateral ON that occurred > 1 year prior to ultrasound examination. We also measured the same parameters in the middle cerebral arteries (MCAs) on both sides in all subjects in both groups. The same measurements were obtained in healthy controls.

RESULTS

The PSV (p < 0.0001), RI (p < 0.0001) and PI (p < 0.0001) in the OA in the eye affected with acute ON were significantly higher than in the unaffected eye. There was no difference in EDV in the OA between affected and unaffected eyes (p > 0.05) in the group with acute ON. We did not observe any significant differences between eyes in either blood flow velocities or the RI or PI (p > 0.05) in the group in the chronic phase of ON or in the control group. All the parameters in the MCAs on both sides were normal in both the acute and chronic groups, as well as in the control group.

CONCLUSIONS

Pathophysiological changes during acute unilateral ON influence orbital haemodynamics, as is indicated by increased PSV, RI and PI in the OA in eyes affected with ON. However, these changes do not persist over longer periods.

Color Doppler imaging in optic neuritis with multiple sclerosis

PURPOSE

To evaluate the retrobulbar hemodynamics in eyes with optic neuritis with multiple sclerosis and to compare these values with those of the unaffected fellow eyes and healthy control eyes.

METHODS

Thirty-four eyes of 17 patients with unilateral optic neuritis and multiple sclerosis and 16 eyes of 16 normal healthy subjects were recruited from the Departments of Ophthalmology and Neurology. The peak systolic and end-diastolic blood flow velocities and resistivity indices of the ophthalmic artery, posterior ciliary arteries and central retinal artery were measured in each eye with optic neuritis, using color Doppler imaging. Then, they were compared with those of the unaffected fellow eyes and healthy control eyes using paired and unpaired Student's t-tests, respectively.

RESULTS

The mean retrobulbar blood flow velocities and mean resistivity index in the ophthalmic artery in the eyes with optic neuritis were not significantly different from the unaffected fellow eyes and healthy control eyes, as well (P>0.05). The mean end-diastolic blood flow velocity in the central retinal artery (P=0.04) was lower and mean resistivity indices in the central retinal (P=0.02) and posterior ciliary arteries (P=0.009) were higher in the eyes with optic neuritis than in the control eyes. In patients with multiple sclerosis, the eyes with optic neuritis had higher resistivity indices in the posterior ciliary (P=0.02) and central retinal arteries (P=0.04) than did the unaffected fellow eyes. The retrobulbar blood flow velocities and resistivity indices of all vessels in the unaffected fellow eyes did not significantly differ from the control eyes (P>0.05).

CONCLUSIONS

This study suggests that optic neuritis with multiple sclerosis is associated with impaired retrobulbar hemodynamics, especially in the posterior ciliary and central retinal arteries when compared with the contralateral unaffected eyes as well as healthy control eyes.

Optic neuritis: evaluation with orbital Doppler sonography

PURPOSE

To evaluate orbital blood flow velocities with Doppler sonography in patients with acute unilateral optic neuritis.

MATERIALS AND METHODS

Orbital Doppler sonography was performed in 20 patients with acute unilateral optic neuritis. Optic neuritis was diagnosed by a neurologist on the basis of clinical presentation, presence of decreased visual acuity, and assessment of visual evoked potentials. The peak systolic and end diastolic velocities and the resistive index were measured in the ophthalmic and central retinal arteries of both orbits. The values obtained from affected and unaffected orbits were compared by using the paired t test.

RESULTS

The peak systolic and end diastolic velocities in the ophthalmic artery were significantly increased in the affected orbits (for peak systolic velocity P <.001, for end diastolic velocity P <.05). Resistive indexes in the ophthalmic arteries did not differ (P >.05). The difference between the peak systolic and end diastolic velocities and resistive indexes in the central retinal arteries of affected and normal eyes was not statistically significant (P >.05).

CONCLUSION

Peak systolic and end diastolic velocities in the ophthalmic artery are increased in patients with acute optic neuritis.

Anterior ischemic optic neuropathy in children: case reports and review of the literature

Anterior ischemic optic neuropathy, infarction of the optic nerve head owing to inadequate perfusion through the posterior ciliary arteries, is a common cause of visual loss in adults but is rarely reported in children, in part because the diagnosis is overlooked. We report two cases of young children undergoing chronic peritoneal dialysis, who suffered bilateral visual loss from anterior ischemic optic neuropathy. Predisposing local anatomic and multiple systemic factors included a small optic nerve head with little cupping, possible intraocular hypertension, and systemic hypotension, hypovolemia, and anemia. The literature on anterior ischemic optic neuropathy is reviewed.