Yu Amano1, Yosuke Kudo1, Hideyuki Kikyo1, Ryoko Imazeki1, Masahiro Yamamoto1, Kazumitsu Amari2, Fumiaki Tanaka3, Ken Johkura4. 1. Department of Neurology, Yokohama Brain and Spine Center, Yokohama, Japan. 2. Department of Neuroendovascular Therapy, Yokohama Brain and Spine Center, Yokohama, Japan. 3. Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan. 4. Department of Neurology, Yokohama Brain and Spine Center, Yokohama, Japan. Electronic address: ke00-johkura@city.yokohama.jp.
Abstract
BACKGROUND AND PURPOSE: Pure midbrain stroke can cause isolated unilateral oculomotor paresis. We attempted to determine whether there is a difference in the oculomotor paresis pattern between pure midbrain infarction and midbrain hemorrhage. METHODS: Pure midbrain stroke patients who presented with isolated unilateral oculomotor paresis were identified from a group of 2447 consecutive patients hospitalized for acute cerebral infarction or hemorrhage during the period May 2008 through April 2014. Detailed oculomotor findings were evaluated in the identified patients per the cause of the stroke. RESULTS: Five patients with infarct and 1 with hemorrhage became our study subjects. Lesions were located in the paramedian area of the midbrain involving the oculomotor fascicles. The pupillary sphincter and inferior rectus muscles were selectively spared in the infarct patients, whereas these muscles were selectively affected in the hemorrhage patient. CONCLUSION: Fibers in the oculomotor fascicle that innervate the levator palpebrae, superior rectus, and inferior oblique muscles appear to be more susceptible to ischemic damage than those that innervate the pupillary sphincter and inferior rectus muscles. Isolated impairment of the pupillary sphincter and inferior rectus muscles may be suggestive of a non-ischemic process.
BACKGROUND AND PURPOSE: Pure midbrain stroke can cause isolated unilateral oculomotor paresis. We attempted to determine whether there is a difference in the oculomotor paresis pattern between pure midbrain infarction and midbrain hemorrhage. METHODS: Pure midbrain strokepatients who presented with isolated unilateral oculomotor paresis were identified from a group of 2447 consecutive patients hospitalized for acute cerebral infarction or hemorrhage during the period May 2008 through April 2014. Detailed oculomotor findings were evaluated in the identified patients per the cause of the stroke. RESULTS: Five patients with infarct and 1 with hemorrhage became our study subjects. Lesions were located in the paramedian area of the midbrain involving the oculomotor fascicles. The pupillary sphincter and inferior rectus muscles were selectively spared in the infarctpatients, whereas these muscles were selectively affected in the hemorrhagepatient. CONCLUSION: Fibers in the oculomotor fascicle that innervate the levator palpebrae, superior rectus, and inferior oblique muscles appear to be more susceptible to ischemic damage than those that innervate the pupillary sphincter and inferior rectus muscles. Isolated impairment of the pupillary sphincter and inferior rectus muscles may be suggestive of a non-ischemic process.