title: Distribution of the corticobulbar tract in the internal capsule.
abstract: It is generally thought that the corticobulbar tract descends through the genu of the internal capsule (IC). There have been several reports that genu lesions cause bulbar symptoms such as facial palsies, dysarthria, and dysphagia. However, the precise location of the corticobulbar tract in the IC remains controversial. The purpose of our study is to assess whether the corticobulbar tract passes through the IC genu. We reviewed 26 patients with selective IC infarction and located the sites related to bulbar symptoms. In addition, using diffusion tensor imaging, we reconstructed tracts passing through the IC in ten subjects without cerebral infarction. Patients with genu infarction, which extended to more than half of the posterior limb of the IC, showed bulbar symptoms. However, patients with genu infarction, which was limited to the genu, did not have bulbar symptoms. In contrast, patients with lesions limited to the posterior limb may show bulbar symptoms. According to statistical maps of the region of interest, the lesions related to bulbar symptoms were localized to areas that were beyond the midpoint of the posterior limb of the IC. In diffusion tensor imaging of subjects without cerebral infarctions, the corticobulbar and corticospinal tracts did not pass through the IC genu. Our data provide evidence that the corticobulbar tract does not pass through the IC genu. The proposed location of the corticobulbar tract in the level of the IC lies beyond the midpoint of the posterior limb.
authors.affiliation: Department of Neurology, National Health Insurance Corporation Ilsan Hospital, Goyang-Shi, South Korea; Department of Neurology, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Soo Hwan
authors.initials: SH
authors.lastname: Yim
authors.forename: Jong Hun
authors.initials: JH
authors.lastname: Kim
authors.forename: Zee-A
authors.initials: ZA
authors.lastname: Han
authors.forename: Seun
authors.initials: S
authors.lastname: Jeon
authors.forename: Jeong Hee
authors.initials: JH
authors.lastname: Cho
authors.forename: Gyu Sik
authors.initials: GS
authors.lastname: Kim
authors.forename: Sun-Ah
authors.initials: SA
authors.lastname: Choi
authors.forename: Jun Hong
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000368:Aged; D020520:Brain Infarction / Q000175:diagnosis / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D020772:Internal Capsule / Q000473:pathology*; D008297:Male; D059906:Neuroimaging; D011712:Pyramidal Tracts / Q000473:pathology*; D063189:Symptom Assessment
keywords: Bulbar symptoms; Cerebral infarction; Corticobular tract; Genu of the internal capsule; Internal capsule; Posterior limb of the internal capsule