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Neuro-Ophthalmology
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
In the assessment of ocular motility disorders, it is necessary to establish the ocular alignment. The principal function of the oculomotor system is to ensure that the object of regard is imaged on the fovea of each eye so that the visual system can devote maximal resolution and binocular fusion giving stereopsis to that object. Diplopia is a common consequence of acquired misalignment of the eyes from whatever cause, but if the subject does not have normal binocular function (for example, if they have had a strabismus in childhood), then there may be no diplopia as the subject has developed the facility to suppress the image from one eye.
Deep brain stimulation programming strategies: segmented leads, independent current sources, and future technology
Published in Expert Review of Medical Devices, 2021
Bhavana Patel, Shannon Chiu, Joshua K. Wong, Addie Patterson, Wissam Deeb, Matthew Burns, Pamela Zeilman, Aparna Wagle-Shukla, Leonardo Almeida, Michael S. Okun, Adolfo Ramirez-Zamora
To optimally utilize directional programming, it is critical to understand the anatomical structural and functional connections of the STN region. The STN is a small lens-shaped structure located in the anterior-lateral part of the midbrain. It is bordered by the substantia nigra pars reticulata (SNr) ventrally; internal capsule anterolaterally; the medial lemniscus posteriorly; the red nucleus, the medial forebrain bundle, the oculomotor nerve fibers medially; rostral zona incerta and fields of Forel dorsally (Figure 4) [64,82,83]. In addition to these neighboring anatomical structures, the STN has been described to be divided into territories (i.e., motor, limbic, and associative) [84]. Majority of studies report using the contacts located in the dorsolateral aspect of the STN to be the most effective and efficient stimulation to reduce PD motor symptoms [74,75]. Some examples of stimulation induced side-effects in STN-DBS include contralateral muscle contractions (internal capsule), dysconjugate gaze or diplopia (oculomotor nerve fibers), autonomic dysfunction (medial zonal incerta, red nucleus, or hypothalamus), paresthesia (medial lemniscus), dysarthria (internal capsule or cerebello-thalamic tracts), and mood changes (substantia nigra, ventromedial limbic region of STN, medial forebrain bundle region).