Ageings and Endings B

1. THE UNIVERSITY OF NEW SOUTH WALES MEDICAL SOCIETY Ageings and Endings B End of Course Revision Tutorial Henry Lin and Arty Selvanathan www.medsoc.org.au

2. As promised! “Chance to win a trip to Fiji” http://www.hotelclub.com.au/getaway/competitionpage.asp

3. Pneumonics OOOTTAFVGVAH Cranial Nerves: OOO To Touch And Feel Virgin Girl’s Vagina And Hymen Standing Room Only Where CNV leaves skull: Superior Orbital Fissure (V1), Foramen Rotundum (V2) & Foramen Ovale (V3) The Zoo Bought Monkey Clothes Branches of CNVII: Temporal, Zygomatic, Buccal, Marginal Mandibular and Cervical Branch www.medsoc.org.au

4. Helpful Resources • 3D Brain App • Youtube videos on tracts • Neuroanatomy made easy

5. Functional Neuroanatomy

6. Important areas

7. Primary Auditory Cortex: Superior Temporal Gyrus • Broca’s Area: Posterior Inferior Frontal Gyrus of the dominant hemisphere (usually left) • Wernicke’s Area: Posterior Superior Temporal Gyrus of dominant hemisphere

8. SomatotopySomatosensory Motor

9. General Rule

10. Tracts in Cord Cross Section

11. Corticospinal Tract • Origin: 40% Primary Motor Cortex, 30% Secondary Motor Cortex, 30% Somatosensory Cortex • 90% Lateral Corticospinal for limb muscle control i.e. voluntary movement • 10% Anterior Corticospinal for axial muscle control i.e. posture • Lateral decussates at Medulla Oblongata • Anterior decussates at Anterior White Commissure

13. Dorsal Column-Medial Lemniscus • Fine touch • Proprioception • Vibration • Discriminative touch (i.e. 2 point discrimination) • Decussate at Medulla Oblongata through the Internal ArcuateFibre (NOT FASICULUS)

16. Spinothalamic Tract • Pain (lateral) • Temperature (lateral) • Crude touch (anterior) • Decussate within the spinal cord within 2 segments through the anterior white commissure

18. Sample Question Cee-Lo was driving ‘round town, and whilst he was gesturing at a girl he recognised, he crashed into a pole and hemi-transected his spinal cord on the left side at T4 (Just below T3 Nerve Root level). • Compare and contrast Upper and Lower motor Neuron disease (6 marks) • Discuss what clinical features would be elicited on exam and explain the underlying mechanism. (10 marks)

19. Question 1. Model Answer

21. Question 2: Model Answer • All Neurological function and physical exam findings will be normal above T4 level (0.5 mark). • In the areas at and below T4, Upper motor neuron signs will be elicited as descending inhibition from the cortex will be lost (0.5 mark).

22. Labelled Diagram for Corticospinal tract (0.5 mark) • Pathway of Corticospinal tract (1.5 mark) -Mention Anterior and Lateral Corticospinal Tract • Therefore if you transect at T4, you will have Hypertonia, Decreased/absent Power and Hyporeflexia/Areflexia on the ipsilateral Left Limb and Trunk, below and at the T4 Level of muscular innervation (1 mark) • Must mention Babinski Reflex upgoing

23. Labelled Diagram for DCML (0.5 mark) • Explain Pathway of DCML (1.5 mark) • MUST mention FasiculusGracilus and FasiculusCuneatus • Therefore if you transect at T4, you will lose Fine touch, Vibration, Proprioception and Discriminative Touch sensation on the Ipsilateral Left side below and at the T4 dermatomaI Level (1 mark)

24. Labelled Diagram for Spinothalamic Tract (0.5 mark) • Explain Pathway of Spinothalamic Tract(1.5 mark) • MUST mention usually ascends 1-2 spinal segments and sensation transmitted via Anterior and Lateral Tracts • Therefore if you transect at T4, you will lose Crude Touch (ant), Pain (lat) & Temperature (lat) sensation on the: • Ipsilateral Left side at T4 & T5 dermatomes (0.5 mark) • Contralateral Right side at T6 dermatome and below (0.5 mark)

25. Bonus marks • 1 mark for discussion of rubrospinal, vestibulospinal, tectospinal & reticulospinal which adds to loss of balance, orienting and posture • 0.5 for identifying condition as Brown Sequard Syndrome • 0.5 for mentioning loss of anal tone, incontinence, etc.

26. Neuroplasticity & Repair: summary • Moral of the first 100 cool stories: Grey matter can get redistributed according to need Good stuff After stroke, recovery and compensation occurs via axonal sprouting and neurogenesis: • Axonal sprouting occurs when the periinfarct cortex upregulates production of growth factors e.g. GAP43, down-regulates growth inhibitory factors like NogoA and activates growth genes in successive waves • Neurogenesis occurs post-stroke when the cytokine EPO is released near the infarct to signal neuroblasts to move from the subventricular zone to the infracted site. 3 phases of brain reorganization during language recovery: • Strongly reduced activation of language areas in left hemisphere in acute stage • Up-regulation of recruitment of homologue language zones to help with language improvement • Normalised activation of left language areas, showing consolidation of language

27. Cerebral Blood Supply • Rote Learning • Internal Carotid Arteries (Anterior Circulation) • Ophthalmic Artery • Anterior Choroidal Artery • Anterior Cerebral Artery • Anterior Communicating Artery • Middle Cerebral Artery (terminal branch) • Vertebral Arteries • Anterior Spinal Artery • Posterior Spinal Artery • Posterior Inferior Cerebellar Artery • Combine to form the Basilar Artery • Basilar Artery • Pontine Arteries • Internal Acoustic Artery • Anterior Inferior Cerebellar Artery • Superior Cerebellar Artery • Posterior Cerebral Artery (terminal branch)

28. Cerebral Blood Supply • Functional Understanding!

32. In Answering a Sample Question • Which artery is affected? • What are the branches of this artery that I know? • Including branches, which areas of the brain are supplied by this artery (and therefore affected)? • What are the functional manifestations of affecting those areas of the brain?

33. Sample Question • Mr X is a 50-year-old Collingwood supporter who has a stroke affecting his middle cerebral artery while standing in his local Centrelink cue. • Detail some of the deficits that one might see in Mr X if a neurological examination was performed.

34. Artery Affected: Middle Cerebral Artery • Branches: ? • Areas supplied by these branches • lateral surfaces of the brain (including the sensory and motor homunculi except for “leg and foot”) • Broca’s and Wernicke’s area (of dominant hemisphere) • Basal ganglia and internal capsule

35. Use Neurological Phrases to Describe Neurological Deficits! • Contralateral hemiparesis/hemiplegia, mostly in muscles of the arm and face) • Loss of sensation on the contralateral side of the face and arm • Aphasia (expressive and/or receptive) if dominant hemisphere involved • Sensory neglect syndrome (if non-dominant hemisphere involved) • Contralateral hemiparesis in the legs as well if the internal capsule is involved • Hyperreflexia and hypertonia (upper motor neuron lesion)

36. Pathophysiology of Stroke • Stroke = “an abnormality of the brain of acute onset caused by a pathological process affecting blood vessels” • 85% due to infarction, 15% due to haemorrhage • Infarction risk factors: atherosclerosis, hypertension, heart disease, diabetes • Causes: thrombosis, embolism, vasospasm, herniation, local vasculitis, poor perfusion without acute obstruction. • TIAs: episodes of non-traumatic focal loss of cerebral function (eg. vision) lasting no more than 24 hours

37. Thrombotic Stroke • Pale infarcts • Superimposed on atheromatous plaques • Key locations: internal carotid artery (carotid bifurcation), middle cerebral artery bifurcation, vertebrobasilar system

38. Embolic Stroke • Haemorrhagic infarcts (≠ haemorrhagic stroke!) • Could be from thrombus in carotid arteries • BUT heart is the most common source of emboli • Mural thrombus overlying myocardial infarct • Valvular vegetations • Thrombus in left atrium (atrial fibrillation) • Often end up in MCA territory

39. Sample Question • Mr Y is a 65-year-old man who has presented to you for rehabilitation following a stroke 3 months ago. His past history includes a myocardial infarct 10 years ago. • What are some of the key risk factors that you would ask for to determine likelihood of stroke? • Is Mr Y’s stroke likely to have been thrombotic or embolic? Contrast the different pathophysiologies of these two subcategories.

40. Parkinson’s Disease and Its Treatment

41. Parkinson’s Disease • Disorder of the basal ganglia (death of dopaminergic neurons in the substantianigra) • Characterized by: • Tremor • Hypokinesia (bradykinesia, akinesia) • Rigidity • Postural instability • Often, eventually develop cognitive and behavioural problems

42. For each drug learn: • Name • Class (‘tag phrase’) • Mechanism of Action • Side Effects/Contraindications

43. Other Points • Pharmacology questions are where you can make up time! • AND don’t forget non-pharmacological methods for treating disease (stretching and strengthening, training in transfer techniques)

44. List of Drugs • Synthetic L-DOPA (Levodopa) • (Peripheral) Dopamine Decarboxylase Inhibitors (Carbidopa) • Monoamine Oxidase B (MOAB) Inhibitors (Selegiline) • Catechol-O-MethylTransferase (COMT) Inhibitors (Entacapone, Tolcapone) • Dopamine Agonists (Bromocriptine, Cabergoline, Pramipexole)

45. The class of drug should give an indication of the mechanism of action!

46. Side Effects • Learn side effects that are common, but also ones that you won’t forget • All dopaminergic drugs: nausea, vomiting, hallucinations • DYSKINESIAS (end-of-dose, but also at peak plasma levels) • Dopamine Agonists: Hypersexuality, gambling addiction, punding

47. Sample Question • Mr Z is a 65-year-old man who has come to see you for a review of his Parkinson’s medications. His current regimen of L-DOPA is causing significant morbidity due to dyskinesias. • List two other drugs used to treat Parkinson’s Disease • For each, state its mechanism of action, and list two side effects of the drug.

48. Sample Answer (One Drug) • Class: Dopamine Agonists • Names: Ropinirole, Pramipexole • Mechanism of Action: Increases stimulation of dopaminergic neurons in the substantianigra • Side Effects: Punding, gambling addiction, hypersexuality

49. Slide Title www.medsoc.org.au