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Title | Description | Type |
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Figure 27: Vascular Supply of the Optic Nerve Head, Choroid and Retina | The ophthalmic artery is a branch of the internal carotid artery, which in turn, supplies the posterior ciliary (to choroid and outer retina) and central retinal (to inner retina) arteries. The central retinal artery (CRA) enters the optic nerve about 1 cm posterior to the globe, and an embolus may ... | Image |
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Figure 2: Parasympathetic Pathway for Pupillary Constriction | A bright light is shone in one eye, light enters the pupil and hyperpolarizes retinal photoreceptors which activates retinal ganglion cells. These signals propagate along the optic nerves, chiasm, optic tracts, and fibers responsible for the light reflex then synapse in the dorsal midbrain (prior to... | Image |
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Figure 43: How the Brain Makes Sense of What It Sees - The Dorsal and Ventral Visual Pathways, and a 3 Tiered Approach to Vision | 1) Ventral ("what") stream - this begins with the ‘P' retinal ganglion cells à parvocellular layers of the lateral geniculate nucleus (LGN, 3-6) à V1/striate cortex (in blue) à V4/V4a (fusiform and lingual gyri) à occipitotemporal regions. 2) Dorsal ("where") stream - this begins with the ‘M... | Image |
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Figure 46: The Course of the 6th (VI) Nerve | The sixth nucleus is located dorsally, adjacent to the 4th ventricle, in the lower pons. The genu of the facial (7th) nerve wraps around the 6th nucleus, creating the facial colliculus, which bulges into the 4th ventricle. After the 6th nerve leaves the pons, it follows a vertical course along the c... | Image |
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Figure 50: Anatomy and Physiology of the Saccadic Pathways | When a saccade is desired (or reflexively triggered), signals project from the saccade-related cortical eye fields to the superior colliculus, which serves to integrate and relay commands to the saccade generating brainstem circuitry. The inferior cerebellar peduncle (ICP) carries climbing fibers to... | Image |
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Figure 51: Lateral Medullary Lesion Causing Saccadic Dysmetria | A lesion of the left lateral medulla and inferior cerebellar peduncle (ICP) will cause decreased climbing fiber inhibition of the left dorsal vermis causing simple-spike (inhibitory) discharge of Purkinje cells to increase. Increased Purkinje cell firing leads to increased inhibition of the ipsilate... | Image |
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Figure 53: Vascular Distribution and Anatomy Relevant to the Lateral Medullary (Wallenberg) Syndrome | This axial section of the medulla highlights those structures that, when damaged, are responsible for the vestibular and ocular motor features of the Wallenberg syndrome. The nucleus prepositus hypoglossi (NPH) and medial vestibular nucleus (MVN) complex is important for horizontal gaze-holding (neu... | Image |
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Figure 61: Vascular Distribution and Anatomy (Including 6th, 7th, 8th Nerves, MLF) of the Pons | In this axial section of the pons, the proximity of the 7th (VII) and 8th (VIII) fascicles can be appreciated, and a lateral inferior pontine syndrome (anterior inferior cerebellar artery, AICA territory), which could involve both of these fascicles, could cause acute prolonged vertigo accompanied b... | Image |
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Figure 64: The Course of the 3rd (III) Nerve | The 3rd nucleus lies at the ventral border of the periaqueductal gray matter, at the level of the superior colliculus. In between the two nuclei is the midline central caudal nucleus (CCN), which innervates bilateral levator palpebrae muscles (explaining how a unilateral nuclear 3rd can cause bilate... | Image |
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Figure 65: Vascular Distribution and Anatomy (Including 3rd Nerve) of the Rostral Midbrain | In this axial section of the midbrain at the level of the superior colliculus, the paired 3rd nuclei are located ventral to the periaqueductal grey, and the midline central caudal nucleus (CCN) is located in between. The fascicles that exit the IIIrd nuclei carry the fibers destined to innervate the... | Image |
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Figure 68: The Course of the 4th (IV) Nerve | The 4th nucleus lies at the ventral border of the periaqueductal gray matter, at the level of the inferior colliculus. The fascicles exit the nucleus dorsally and decussate at the anterior medullary velum (anterior floor of the fourth ventricle), and then exit the brainstem dorsally. The peripheral ... | Image |
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Figure 69: Vascular Distribution and Anatomy (Including 4th Nerve) of the Caudal Midbrain | In this axial section of the midbrain at the level of the inferior colliculus, the 4th nuclei are located ventral to the periaqueductal grey, dorsal to the medial longitudinal fasciculus (MLF) and medial to the oculosympathetic tract. Fascicles exit the nucleus dorsally and decussate at the anterior... | Image |
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Figure 80: Vascular Distribution and Anatomy Relevant to the Medial Medullary Syndrome | This axial section of the medulla highlights those structures that, when damaged, are often responsible for spontaneous upbeat nystagmus (UBN). The nucleus of Roller and nucleus intercalatus normally have an inhibitory influence over the cerebellar flocculus, and when there is a lesion of Roller/int... | Image |
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Five Common Ocular Motor Signs in Cerebellar Disorders - Saccadic Hypermetria, Saccadic Pursuit & VOR Suppression, Gaze-evoked & Rebound Nystagmus | (1) Saccadic hypermetria - an overshoot of the visual target (2) Saccadic smooth pursuit - due to impaired pursuit and low gain, saccades are needed to keep up with the visual target. This gives it a ‘choppy' appearance. (3) Saccadic vestibulo-ocular reflex (VOR) suppression - another... | Image/MovingImage |
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Fixation and Gaze Holding | Fixation and gaze-holding: assess for nystagmus or saccadic intrusions by observing the eyes in primary position. Then instruct the patient to look in each position of gaze, and to hold that position to assess for gaze-evoked nystagmus. In doing so, motility can also be evaluated with both eyes view... | Image/MovingImage |
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The Gans Maneuver for Right Posterior Canal Benign Paroxysmal Positional Vertigo | This maneuver is recommended for individuals with cervical restrictions or precautions, as the maneuver avoids cervical hyperextension and may reduce cervical pain associated with repositioning maneuvers. The Epley maneuver has higher subjective and objective success rates compared to the Gans maneu... | Text |
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The Gans Maneuver for Right Posterior Canal Benign Paroxysmal Positional Vertigo (Video) | This maneuver is recommended for individuals with cervical restrictions or precautions, as the maneuver avoids cervical hyperextension and may reduce cervical pain associated with repositioning maneuvers. The Epley maneuver has higher subjective and objective success rates compared to the Gans maneu... | Image/MovingImage |
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Gaze-Evoked Nystagmus & Slow Saccades Due to Anti-GAD Antibodies in a Patient with Stiff Person Syndrome | This is a 70-year-old woman with a several year long history of imbalance and stiffness. Exam demonstrated axial and lower extremity stiffness, and ocular motor exam demonstrated gaze-evoked nystagmus (e.g., right-beating in right gaze, left-beating in left gaze, up-beating in up gaze), and mild to ... | Image/MovingImage |
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Gaze-Evoked, Rebound, and Centripetal Nystagmus in Cerebellar Degeneration | A 68-year-old female reported a 2-year history of progressive gait imbalance, falls, dizziness and vertical oscillopsia. She described that dizziness and oscillopsia were worst when looking down. There was no family history of ataxia. Composite gaze with fixation was recorded with video-oculography ... | Image/MovingImage |
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Gufoni Maneuver for Left Horizontal Canal BPPV, Canalithiasis (Geotropic Nystagmus) | The Gufoni maneuver may be preferable to the BBQ roll, as the Gufoni maneuver does not require the individual to roll or be in a prone position, making the maneuver more feasible to complete for individuals who are elderly, obese and/or experience immobility. Antecedently, some clinicians remember t... | Text |
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Gufoni Maneuver for Left Horizontal Canal BPPV, Canalithiasis (Geotropic Nystagmus) (Video) | The Gufoni maneuver may be preferable to the BBQ roll, as the Gufoni maneuver does not require the individual to roll or be in a prone position, making the maneuver more feasible to complete for individuals who are elderly, obese and/or experience immobility. Antecedently, some clinicians remember t... | Image/MovingImage |
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Gufoni Maneuver for Right Horizontal Canal-Cupulolithiasis (Apgeotropic Nystagmus) | The Gufoni Maneuver can be used to treat horizontal canal cupulolithaisis. 1. The patient starts in a seated position. 2. The patient transitions quickly to lying on their affected side. 3. The patient lies on their affected side for two minutes with the head in a neutral position. 4. The patient's ... | Text |
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Gufoni Maneuver for Right Horizontal Canal-Cupulolithiasis (Apgeotropic Nystagmus) (Video) | The Gufoni Maneuver can be used to treat horizontal canal cupulolithaisis. 1. The patient starts in a seated position. 2. The patient transitions quickly to lying on their affected side. 3. The patient lies on their affected side for two minutes with the head in a neutral position. 4. The patient's ... | Image/MovingImage |
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Head-Shaking (2-3 Hz) | Head-shaking: instruct the patient to close their eyes and perform active rapid head-shaking at 2-3 Hz for ~15 secs. If a unilateral vestibulopathy is present, head-shaking-induced (contralesional) nystagmus is often provoked, with the slow phase toward the affected ear. With central lesions, the ny... | Image/MovingImage |
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Head-Shaking-Induced Nystagmus Following Ramsay Hunt Vestibulopathy | 𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: This is a 50-year-old man who experienced the abrupt onset of imbalance, dizziness and left-sided hearing loss 4 months prior to this examination. He was found to have herpetic vesicles in the left external auditory canal... | Image/MovingImage |