PURPOSE: To investigate through the use of cerebral Doppler technology whether emboli are a more common cause of nonarteritic anterior ischemic optic neuropathy (NAION) than previously recognized. METHODS: Eleven patients with a recent (<121 days) history of nonarteritic anterior ischemic optic neuropathy and 10 age-matched controls (event > 121 days) were examined using a Nicolet Pioneer 2020 transcranial Doppler (TCD) unit with a 2-MHz bilateral continuous monitoring capability. The right and left middle cerebral arteries were evaluated simultaneously for 30 minutes at a depth of 50 to 55 mm, and the number of emboli, blood flow velocities, and pulsatility indices were recorded. Data were stored by computer, and hard-copy color recordings were made. RESULTS: None of 11 patients with a recent history of NAION demonstrated microemboli by TCD examination. One patient in the control group who had a remote history of NAION had a microembolic event rate of 12 per hour (six over 30 minutes). This patient had a history of prosthetic cardiac valve replacement and was taking anticoagulation medication at the time of the examination. CONCLUSIONS: Our study did not reveal an increased incidence of embolic events in patients with NAION when they were examined in a transcranial Doppler study of the middle cerebral arteries. This study does not support embolism as a frequent cause of NAION.
PURPOSE: To investigate through the use of cerebral Doppler technology whether emboli are a more common cause of nonarteritic anterior ischemic optic neuropathy (NAION) than previously recognized. METHODS: Eleven patients with a recent (<121 days) history of nonarteritic anterior ischemic optic neuropathy and 10 age-matched controls (event > 121 days) were examined using a Nicolet Pioneer 2020 transcranial Doppler (TCD) unit with a 2-MHz bilateral continuous monitoring capability. The right and left middle cerebral arteries were evaluated simultaneously for 30 minutes at a depth of 50 to 55 mm, and the number of emboli, blood flow velocities, and pulsatility indices were recorded. Data were stored by computer, and hard-copy color recordings were made. RESULTS: None of 11 patients with a recent history of NAION demonstrated microemboli by TCD examination. One patient in the control group who had a remote history of NAION had a microembolic event rate of 12 per hour (six over 30 minutes). This patient had a history of prosthetic cardiac valve replacement and was taking anticoagulation medication at the time of the examination. CONCLUSIONS: Our study did not reveal an increased incidence of embolic events in patients with NAION when they were examined in a transcranial Doppler study of the middle cerebral arteries. This study does not support embolism as a frequent cause of NAION.