Published online before print December 11, 2002, 10.1148/radiol.2262011915
(Radiology 2003;226:355-358.)
© RSNA, 2003
Optic Neuritis: Evaluation with Orbital Doppler Sonography1
Kamil Karaali, MD,
Utku 
enol, MD,
Hülya Ayd
n, MD,
Can Çevikol, MD,
Ali Apaydn, MD and
Ersin Lüleci, MD
1 From the Departments of Radiology (K.K., U.S., C.C., A.A., E.L.) and Neurology (H.A.), Akdeniz University School of Medicine, 07070 Antalya, Turkey. From the 2001 RSNA scientific assembly. Received November 27, 2001; revision requested February 8, 2002; revision received April 17; accepted June 3. Address correspondence to K.K. (e-mail: karaali@med.akdeniz.edu.tr).
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ABSTRACT
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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.
© RSNA, 2003
Index terms: Arteries, opthalmic, 1724.91 • Blood, flow dynamics, 1724.91 • Nerves, optic, 144.20 • Neuritis, 144.20 • Orbit, US, 1724.12983, 1724.12984 • Ultrasound (US), Doppler studies, 1724.12983, 1724.12984
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INTRODUCTION
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Optic neuritis is a clinical disorder characterized by acute vision loss. Visual acuity decreases within a few days. Pain during eye movement and defects in pupillary afferent reflexes are also present. Although the disorder is most commonly associated with, and may be the first manifestation of, multiple sclerosis, it can occur as a result of vasculitic or inflammatory processes. Its diagnosis is based on clinical presentation and visual evoked potential (VEP) measurement. In VEP assessment, electrical activity of the occipital cortex is recorded after visual stimuli, and each eye is tested independently. If there is damage to the visual pathway, such as demyelination, the response of the cortex is delayed or absent. Although VEP is a sensitive method for detection of abnormalities, the exact anatomic location of the lesion cannot be assessed. Magnetic resonance (MR) imaging may be helpful for making a diagnosis, especially if the clinical presentation is atypical and results of VEP measurement are inconclusive (1). MR imaging is usually requested in patients with optic neuritis to evaluate probable brain lesions.
Orbital Doppler sonography is a relatively new method. Normal and abnormal flow patterns of orbital vessels were described by Erickson et al in 1989 (2). Since then, orbital blood flow changes have been demonstrated in various disorders, such as glaucoma (3), Behçet disease (4), and brain death (5). The purpose of our study was to evaluate orbital blood flow velocities with Doppler sonography in patients with acute unilateral optic neuritis.
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MATERIALS AND METHODS
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Patients
Between December 1999 and March 2001, acute unilateral optic neuritis was diagnosed in 20 patients at our institution. All 20 patients (six men and 14 women; age range, 21–50years; mean age, 30 years ± 9.4) were included in our study. The patients presented with acute loss of vision and pain in the affected eye. The duration of the symptoms ranged from 2 to 7 days (mean, 4.2 days). All patients underwent neurologic and ophthalmologic examinations, including assessment of visual acuity, direct ophthalmoscopy, and VEP measurement. Optic neuritis was diagnosed by a neurologist on the basis of typical clinical findings at presentation: acute and painful loss of vision, presence of decreased visual acuity, and abnormal VEP findings (prolonged response). The cause of optic neuritis was presumed to be multiple sclerosis in 18 patients and idiopathic in two.
Sonography and MR Imaging
Patients were informed about the Doppler technique, and consent was obtained. Declaration of Helsinki principles were followed for the study.
Orbital Doppler sonography was performed within 1 day of presentation (mean of 5.2 days after the start of the patients’ symptoms) and before the initiation of medical treatment. One of the authors (K.K.) performed all Doppler examinations. Sonography was performed with color Doppler units and a 7.5-MHz linear-array transducer (model SSA-270A or SSA-350A; Toshiba, Nasu, Japan). The Doppler examiner was blinded to the side of involvement. Sterile coupling gel was applied to closed eyelids, and real-time gray-scale and color-flow images were obtained. Central retinal arteries were found within the distal 0.5 cm of the optic nerves. Ophthalmic arteries were traced in the deeper portions of the orbits, lateral to the optic nerves. We obtained peak systolic and end diastolic velocities and resistive indexes in the ophthalmic and central retinal arteries of both orbits.
Because the referring clinician requested evaluation of probable brain lesions, MR imaging was also performed in all patients within 1 day after Doppler examination by using a 1.5-T unit (Gyroscan ACS-NT; Philips, Best, the Netherlands). For the routine brain evaluation, sagittal T2-weighted (4,406/100 [repetition time msec/echo time msec], echo train length of 15), transverse T1-weighted (562/14), transverse T2-weighted (4,401/100, echo train length of 15), and transverse fluid-attenuated inversion recovery (6,000/100/2,000 [repetition time msec/echo time msec/inversion time msec]) sequences were used. In 14 patients, magnetization transfer contrast–weighted transverse images (453/13) were also obtained before and after intravenous administration of 0.1 mmol of gadopentetate dimeglumine (Magnevist; Schering, Berlin, Germany) per kilogram of body weight. In addition, all patients underwent short inversion time inversion-recovery sequences (2,500/90/140) and spectral presaturation inversion recovery combined with fluid-attenuated inversion recovery sequences (5,000/100/2,000) to evaluate optic nerves. Two authors (U.., C.Ç.) interpreted the MR images; decisions were reached by consensus. Although the interpreters were blinded to the Doppler sonographic findings, they had been given clinical information by the neurologist and knew the side of involvement. Routine brain images were evaluated for the presence of probable demyelinating plaques. Optic nerves were evaluated for the presence of increased signal intensity (by comparing them with normal white matter) and enlargement (by subjectively comparing the appearance with that on the normal side). MR imaging findings were used to help confirm the clinical diagnosis of optic neuritis. The demonstration of enlargement of or increased signal intensity in the optic nerve with at least one sequence was considered a positive MR imaging finding that confirmed the clinical diagnosis.
Statistical Evaluation
We compared the peak systolic and end diastolic velocities and resistive indexes of the ophthalmic and central retinal arteries in affected and normal orbits. The paired t test was used to analyze the data, and P value of less than .05 was used to assign statistical significance.
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RESULTS
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Optic neuritis involved the right orbit in 12 patients (60%) and the left orbit in eight (40%). Increased signal intensity in and enlargement of the canalicular and orbital segments of the optic nerve were seen with at least one MR sequence in all of the involved orbits.
The mean values obtained from the Doppler measurements are presented in Tables 1 and 2. For all patients, the peak systolic and end diastolic velocities in the ophthalmic artery of affected orbits were higher than those in normal orbits; the difference was statistically significant. The mean peak systolic velocity was 53.4 cm/sec ± 11.5 in affected orbits and 28.8 cm/sec ± 6.7 in normal orbits (P < .001). The difference in the mean peak systolic velocity between affected and normal orbits was 24.6 cm/sec ± 10.8. The mean end diastolic velocity was 14.3 cm/sec ± 5.5 in affected orbits and 9.7 cm/sec ± 2.5 in normal orbits (P < .05). The difference in the mean end diastolic velocity between affected and normal orbits was 4.6 cm/sec ± 5.6. The resistive indexes of ophthalmic arteries did not differ between affected and normal sides (P > .05) (Figs 1, 2).
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Figure 1a. Images obtained in a 28-year-old woman with optic neuritis in the left eye. (a) Coronal MR image obtained with spectral presaturation inversion recovery combined with fluid-attenuated inversion recovery sequences (5,000/100/2,000) shows enlargement of and increased signal intensity in the left optic nerve (arrow). (b) Doppler spectra obtained in the left ophthalmic artery of the same patient. The peak systolic velocity was 52 cm/sec, and the end diastolic velocity was 8 cm/sec. (c) Doppler spectra obtained in the right ophthalmic artery in the same patient. The peak systolic velocity was 22 cm/sec, and the end diastolic velocity was 8 cm/sec.
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Figure 1b. Images obtained in a 28-year-old woman with optic neuritis in the left eye. (a) Coronal MR image obtained with spectral presaturation inversion recovery combined with fluid-attenuated inversion recovery sequences (5,000/100/2,000) shows enlargement of and increased signal intensity in the left optic nerve (arrow). (b) Doppler spectra obtained in the left ophthalmic artery of the same patient. The peak systolic velocity was 52 cm/sec, and the end diastolic velocity was 8 cm/sec. (c) Doppler spectra obtained in the right ophthalmic artery in the same patient. The peak systolic velocity was 22 cm/sec, and the end diastolic velocity was 8 cm/sec.
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Figure 1c. Images obtained in a 28-year-old woman with optic neuritis in the left eye. (a) Coronal MR image obtained with spectral presaturation inversion recovery combined with fluid-attenuated inversion recovery sequences (5,000/100/2,000) shows enlargement of and increased signal intensity in the left optic nerve (arrow). (b) Doppler spectra obtained in the left ophthalmic artery of the same patient. The peak systolic velocity was 52 cm/sec, and the end diastolic velocity was 8 cm/sec. (c) Doppler spectra obtained in the right ophthalmic artery in the same patient. The peak systolic velocity was 22 cm/sec, and the end diastolic velocity was 8 cm/sec.
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Figure 2a. Images obtained in a 24-year-old man with optic neuritis in the right eye. (a) Coronal short inversion time inversion-recovery MR image (2,500/90/140) shows enlargement of and increased signal intensity in the right optic nerve (arrow). (b) Doppler spectra obtained in the right ophthalmic artery in the same patient. The peak systolic velocity was 58 cm/sec, and the end diastolic velocity was 16 cm/sec. (c) Doppler spectra obtained in the left ophthalmic artery in the same patient. The peak systolic velocity was 37 cm/sec, and the end diastolic velocity was 8 cm/sec.
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Figure 2b. Images obtained in a 24-year-old man with optic neuritis in the right eye. (a) Coronal short inversion time inversion-recovery MR image (2,500/90/140) shows enlargement of and increased signal intensity in the right optic nerve (arrow). (b) Doppler spectra obtained in the right ophthalmic artery in the same patient. The peak systolic velocity was 58 cm/sec, and the end diastolic velocity was 16 cm/sec. (c) Doppler spectra obtained in the left ophthalmic artery in the same patient. The peak systolic velocity was 37 cm/sec, and the end diastolic velocity was 8 cm/sec.
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Figure 2c. Images obtained in a 24-year-old man with optic neuritis in the right eye. (a) Coronal short inversion time inversion-recovery MR image (2,500/90/140) shows enlargement of and increased signal intensity in the right optic nerve (arrow). (b) Doppler spectra obtained in the right ophthalmic artery in the same patient. The peak systolic velocity was 58 cm/sec, and the end diastolic velocity was 16 cm/sec. (c) Doppler spectra obtained in the left ophthalmic artery in the same patient. The peak systolic velocity was 37 cm/sec, and the end diastolic velocity was 8 cm/sec.
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The peak systolic and end diastolic velocities and resistive indexes in the central retinal arteries of affected and normal orbits did not differ significantly (P > .05).
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DISCUSSION
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In our study, the peak systolic and end diastolic velocities of the ophthalmic artery were found to be increased in eyes with acute optic neuritis. To our knowledge, this finding has not been reported previously. The ophthalmic artery is the main artery of the orbit, and it enters through the optic canal together with the optic nerve (2). Enlargement of the optic nerve is the result of the inflammation in optic neuritis (6,7). Typically, maximum visual loss occurs within 1–7 days after onset in patients with optic neuritis, and the major cause of the initial loss of visual acuity is likely to be nerve swelling (7). In our opinion, the enlarged optic nerve compresses the ophthalmic artery within the optic canal, and this compression may be the cause of the increased peak systolic and end diastolic velocities. Because peak systolic and end diastolic velocities were both increased, the resistive index remained unchanged.
To our knowledge, only one group of investigators (7) performed Doppler sonography to evaluate orbital blood flow velocities in optic neuritis. In that study, however, only resistive indexes of the central retinal artery were evaluated; velocities were not measured and the ophthalmic artery was not evaluated. The results obtained from affected and normal orbits were compared, and resistive indexes in the central retinal arteries were found to be increased in the affected sides. The authors attributed the increased resistive indexes to the nerve swelling and resultant resistance to flow. In our study, in contrast to the study by Elvin et al (7), the velocities and resistive indexes of the central retinal arteries in affected and normal orbits did not differ significantly. The interval between presentation and Doppler examination, however, was different in the two studies. Elvin et al (7) performed Doppler examination a mean of 27 days after the onset of symptoms. Because we performed orbital Doppler sonography within 1 day of presentation, the mean interval between the onset of symptoms and Doppler sonography in our study was 5.2 days. This difference may be the cause of the inconsistent results obtained in the central retinal arteries. Elvin et al used gray-scale sonography to measure the diameter of the optic nerve and found them to be increased in affected orbits. The diameter of the optic nerve is measured immediately behind the globe. The diameter of the segment within the bony optic canal cannot be measured with sonography. We think that enlargement of the canalicular segment of the optic nerve can be indirectly shown by demonstrating increased ophthalmic artery velocities with Doppler sonography.
We acknowledge that our study is limited because our findings are based on data obtained from 20 patients, which is a small group. To determine the sensitivity and specificity of this technique, data obtained from larger groups may be helpful. As a noninvasive method, Doppler sonography may play a role in the diagnosis of optic neuritis.
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FOOTNOTES
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Abbreviation: VEP = visual evoked potential
Author contributions: Guarantor of integrity of entire study, K.K.; study concepts and design, K.K., U.S.; literature research, K.K.; clinical studies, K.K., H.A., C.C.; data acquisition, K.K., U.S., C.C.; data analysis/interpretation, K.K., A.A., E.L.; statistical analysis, U.S.; manuscript preparation, K.K., C.C.; manuscript definition of intellectual content, K.K., U.S.; manuscript editing, U.S.; manuscript revision/review and final version approval, A.A., E.L.
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ABSTRACT
INTRODUCTION
