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  1. 1. MEDULLAMICHAEL STAR, MDDepartment of NeurologyLoyola University Medical CenterJune 2012 1
  2. 2. CASE 1 2
  3. 3. BASICS 3
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  5. 5. CROSSROADSOF…YOUR BRAINAscending Tracts:1) Dorsal column tract (fine touch, vibration, proprioception)  gracileand cuneate nuclei  lemniscal decussation  medial lemniscus thalamus2) Spinothalamic (pain, temp.)  Thalamus -Decussation at/above spinal level, not medulla!Descending Tracts:1) Corticospinal tract  medullary pyramid  pyramidal decussation Lateral and anterior corticospinal tract2) Medial longitudinal fasciculus (gaze/head movement)  Vestibularnuclei (pons/medulla)  spinal cord -Also ascends to CN III, IV, and VI3) Descending tract of CN V (pain, temperature, crude touch)  Cellbodies in in trigeminal ganglion  spinal nucleus of CN V 5
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  7. 7. CRANIAL NERVE NUCLEIIN THE MEDULLA• Hypoglossal nucleus (XII), dorsal motor nucleus of vagus (X), and solitary tract and nucleus (sensory for VII, IX, and X) are found below the 4th ventricle• Hypoglossal nucleus sends its fibers ventrally between the pyramid and inferior olivary nucleus• Ambiguus nucleus has motor fibers which exit laterally to nerves IX and X to control swallowing and vocalization• Dorsal motor nucleus of X sends its fibers laterally (along with the ambiguus nucleus fibers) to control parasympathetic tone in heart, lungs, and abdominal viscera• Solitary nucleus that receives axons from VII, IX, and X conveys information about taste via the VPM nucleus in the the thalamus which projects to cortex (area 43)• 4 Vestibular nuclei (superior, inferior, medial, and lateral) are found partially in the medulla, partially in the pons 7
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  14. 14. CASE 1 REVISITED 14
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  17. 17. CASE 1 DISCUSSED 17
  18. 18. CASE 2A 62 year old man with history of smoking, obesity, diabetesmellitus type 2, hypertension, and hyperlipidemia presentsbecause for the past 2 days he has been having problemstalking and swallowing. He feels that he has developedsomething of a lisp and that when he eats, he feels like thefood is not moving to the back of his mouth. His wife thinkshe is crazy. Patient denies any other symptoms.On physical exam, you note tongue deviation to the rightside.What is the diagnosis? Where is the lesion? 18
  19. 19. HINT 19
  20. 20. CASE 2 DISCUSSEDThe patient’s tongue deviates to the right because ofweakness of the left tongue. While multiple locations couldpossibly explain this lesion, the sudden onset of symptomsis likely an ischemic stroke of the left paramedian branchesof the anterior spinal artery affecting the fibers of the leftcranial nerve 12, which causes ipsilateral hemiparalysis ofthe tongue 20
  21. 21. CASE 3A 32 year old woman with Factor V Leiden and on OCPspresents to the ED with complaints of dizziness and falls for thelast 4 days. The patient note the room “feels like it’s spinningaround me.” The patient first presented to Loretto two daysprior, where, because they don’t have an MRI, they told her shehad BPPV and demonstrated how to do the Epley maneuver anddischarged her. She presents now because she says it has nothelped. Patient notes that dizziness does not resolve withsitting, standing, or laying supine, and Dix-Hallpike, whileannoying, did not make her more or less dizzy. You perform anMRI, but the patient gets nauseous midway through the MRI andstarts moving. You note no lesions in the cerebellum orsupratentorially, however, the brain stem isn’t visualized due tomotion artifacts. ENT performs vestibular testing which rulesout peripheral vertigo.Where could the lesion be? 21
  22. 22. HINT 22
  23. 23. CASE 3One possible explanation for the patient’s symptoms alongwith an otherwise negative MRI and vestibular testing is anischemic stroke of the posterior inferior cerebellar artery(PICA) affecting the Vestibular nuclei. 23