Trans-orbital sonography versus visual evoked potentials in acute demyelinating optic neuritis.

Area of Science:

• Ophthalmology
• Neurology
• Medical Imaging

Background:

• Optic neuritis (ON) is an inflammatory demyelinating condition causing acute visual loss, often associated with multiple sclerosis (MS).
• Diagnosis of ON is typically based on clinical history and examination findings.

Purpose of the Study:

• To evaluate the diagnostic accuracy of ultrasound-measured optic nerve sheath diameter (ONSD) in acute optic neuritis.

Main Methods:

• A prospective observational study involving 25 patients with acute demyelinating ON and 25 matched controls.
• Clinical assessment, pattern and flash visual evoked potentials (P-VEP), and trans-orbital sonography (TOS) to measure ONSD were performed.

Main Results:

• ONSD was significantly thicker in ON patients (0.6 ± 0.05 cm unilateral, 0.6 ± 0.1 cm bilateral) compared to controls (0.52 ± 0.06 cm).
• A cutoff ONSD of 0.57 cm showed significant diagnostic value (P < 0.001/0.04).
• TOS demonstrated 68% sensitivity and 88% specificity for ON diagnosis, with a negative correlation between ONSD thickness and visual acuity (r = -0.613, P < 0.05).

Conclusions:

• Optic nerve sheath diameter measurement via TOS is a noninvasive, inexpensive bedside test that supports ON diagnosis.
• While valuable, TOS demonstrates lower sensitivity and specificity compared to P-VEP for diagnosing optic neuritis.