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Cortical function as experienced by a neurosurgeon

Cortical function as experienced by a neurosurgeon. Kathryn Holloway, MD Prof of Neurosurgery. Techniques of Cortical Mapping. I Lesional Studies - Correlation of functional deficit with autopsy or Gyral Anatomy on structural imaging studies II Electrocorticography (1) Awake craniotomy

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Cortical function as experienced by a neurosurgeon

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  1. Cortical function as experienced by a neurosurgeon Kathryn Holloway, MD Prof of Neurosurgery

  2. Techniques of Cortical Mapping I Lesional Studies - Correlation of functional deficit with autopsy or Gyral Anatomy on structural imaging studies II Electrocorticography (1) Awake craniotomy (2) Implantation of cortical grid with extraoperative monitoring III Functional Imaging fMRI PET IV MEG magnetic source imaging correlated with MRI

  3. Lesional Studies

  4. Speech areas as defined by lesional studies

  5. Dominance • In 95% of population the left hemisphere is dominant • Essentially “all” right handed patients with a normal brain are left dominant • A small portion of left handed individuals are right or mixed dominant for speech • Dominance can be assessed by anesthetizing one hemisphere via an intracarotid amytal injection

  6. Types of aphasia • Wernickes • Posterior dominant temporal lobe extending around the angular gyrus into the parietal lobe • Loss of comprehension • Speech tends to be fluid but without content • They are relatively unaware of their deficits • Broca’s • Dominant inferior frontal gyrus • Preserved comprehension • Word generation ability (speech & written ) lost • Patients very aware of deficit and are frustrated

  7. Traditional speech areas Broca‘s Wernickes

  8. Speech • Can, in fact, block naming as well as comprehension in the dominant temporal lobe (Wernicke’s area) • However if there is a comprehension deficit, the lesion is in the dominant temporal lobe • Severe speech production problems without any comprehension problems will be reliably localized to the dominant inferior frontal gyrus

  9. Left temporal lobe bleed

  10. Hematoma in Broca’s area

  11. Names of gyri and corresponding Brodman areas

  12. The primary visual cortex is identified on a mid-saggittal cut showing the calcarine fissure

  13. Visual Cortex Visual cortex

  14. Brodman #’s & Gyri names

  15. G.S. - History 25 year old RH WM working in Poland Onset of right visual field obscurations followed by right homonymous hemianopsia One seizure consisting of a light in the right visual field associated with altered sensation in the right hand

  16. G.S. - Exam No weakness Right homonymous hemianopsia

  17. Right inferior quadrantanopsia

  18. Area of destruction in visual cortex by bleed

  19. Area of AVM,area of cortical destruction below this

  20. AVM exposed by retracting brain to see medial surface of hemisphere Area of craniotomy Retracted parietal lobe Falx at midline

  21. AVM exposed by retracting brain to see medial surface of hemisphere Retracted parietal lobe Saggital sinus, falx, midline

  22. Postop angio shows no residual AVM Post-resection angio Pre-resection angio

  23. Damage to secondary association areas give less specific deficits

  24. K.S. - History & Exam 39 year old RH WF Onset of seizures at age 2 Unresponsive to medication Developmentally delayed Normal examination

  25. K.S. - Seizure Types Age 2 - episodes of blindness Age 8 – generalized tonic clonic seizures Teens – sees colors or micropsia or macropsia followed by unresponsiveness with a postictal aphasia Other seizures

  26. Tumor in visual association areas

  27. Patient’s representation of visual hallucinations

  28. The motor/sensory strip can readily be identified on MRI imaging by noting the first vertical gyrus posterior to the horizontal frontal gyri

  29. Precentral sulcus is most anterior vertical sulcus

  30. Motor Sensory Cortex

  31. Distribution of motor/sensory function along central sulcus is well known

  32. F.R. - History 37 year old RH WF Gradual onset of headaches, right sided weakness New onset right sided jerking followed by generalized tonic clonic seizures

  33. F.R. - Exam No aphasia Right sided facial weakness sparing forehead Right arm- spastic paresis Right leg – mild spasticity

  34. MRI

  35. Axial view

  36. Saggital view

  37. Exposure anterior ear Top of head posterior

  38. Cored and Delivered

  39. Resection exposes frontal gyri Motor strip

  40. F.R. - Postoperative Course Resolution of all deficits

  41. In contrast speech and memory function can only be generally localized

  42. Speech areas as defined by lesional studies

  43. Traditional speech areas Broca‘s Wernickes

  44. Speech areas in a population of 117 patients

  45. R.B. - History 14 yo RH WM History of partial complex seizures since the age of 15 months EEG - Left mesial temporal lobe epilepsy with early lateral spread Uncontrolled on Primidone, Tegretol, Dilantin, Valproate, or Tranxene

  46. R.B. - Physical Exam Normal

  47. R. B. – Neuropsychological Evaluation Moderate dominant hemisphere damage

  48. Mesial Sclerosis • Left hippocampus is shrunken and scarred • This is a frequent source of seizures that don’t respond to medication • The dominant temporal lobe is also the area of the brain responsible for verbal memory and speech

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