Localization in the Neuraxis
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Localization in the Neuraxis Presentation Transcript

  • 1. Localization in the Neuraxis
    • Resident Core Lecture Series
    • David R. Renner, MD
    • University of Utah
    • Department of Neurology
  • 2. The Approach to a Patient with Neurologic Disease
    • The H&P accurately localizes most lesion
    • Divisions of the neuraxis have specialized functions
    • Damage to various divisions produce unique clinical deficits
    • Localization is important
      • investigation modalities differ widely depending upon the level affected
  • 3. Divisions of the Neuraxis
    • Cortical Brain
    • Subcortical Brain
    • Brainstem
    • Cerebellum
    • Spinal Cord
    • Root
    • Peripheral Nerve
    • Neuromuscular Junction
    • Muscle
  • 4. Neurologic Examination
    • Higher Cortical Function
    • Cranial Nerves
    • Cerebellar Function
    • Motor
    • Sensory
    • Deep Tendon Reflexes
    • Pathologic Reflexes
  • 5. Divisions of the Neuraxis
    • Cortical Brain
    • Subcortical Brain
    • Brainstem
    • Cerebellum
    • Spinal Cord
    • Root
    • Peripheral Nerve
    • Neuromuscular Junction
    • Muscle
  • 6. Cortical Brain
    • Depends upon hemispheric dominance
    • Non-neurologists generalize:
      • right: visual/spatial, perception and memory
      • left: language and language dependent memory
    • Through detailed examination, neurologists should lateralize and localize within a lobe
  • 7. Cortical Brain
    • Frontal Lobe :
      • L:
        • Broca’s Aphasia
      • R: ?
      • B:
        • precentral gyrus: motor homunculous
        • supplementary motor cortex: eye and head turn
        • prefrontal cortex: personality, initiative
        • paracentral lobule: cortical inhibition of voiding B/B
  • 8. Cortical Brain
    • Parietal Lobe :
      • R:
        • anosognosia: left hemineglect
        • dressing and constructional apraxia
        • geographic agnosia
      • L:
        • Gerstman’s Tetrad (not triad): L/R confusion, finger agnosia, acalculia, agraphia without alexia
        • Werneke’s Aphasia
  • 9. Cortical Brain
    • Parietal Lobe :
      • B:
        • abnormal posture and passive movement
        • localization of touch
        • 2-point discrimination
        • astereognosis
        • perceptual rivalry
  • 10. Cortical Brain
    • Temporal :
      • R:
        • hearing language
      • L:
        • hearing sounds, rhythm, rhythm, music
      • B:
        • learning and memory: mid/inferior gyri
        • olfaction: limbic
        • Auditory cortex: Heschel’s gyrus
  • 11. Cortical Brain
    • Occipital Lobe :
      • R:
        • micropsia
        • macropsia
      • B:
        • visual hallucinations: elemental and unformed
        • prosopagnosia: familiar faces
        • cortical blindness: striate cortices, normal pupil rx
        • Anton’s: (para)striate, denial of obvious blindness
        • Balint’s: inability to direct voluntary gaze with visual agnosia
  • 12. Neurologic Examination when Cortical Brain is Lesioned
    • Higher Cortical Function
      • aphasia, apraxia, agnosia
    • Cranial Nerves : normal, unless forced eye deviation
    • Cerebellar Function : normal
    • Motor :
      • weakness of face/arm>leg (or vice versa) if motor homunculous is hit
      • hypertonia if corticospinal tracts are hit
    • Sensory :
      • sensory abn of face/arm>leg (or vice versa)
    • Deep Tendon Reflexes :
      • hyper-reflexia
    • Pathologic Reflexes :
      • Babinski’s reflex if corticospinal tracts are hit
      • Frontal release signs (nonspecific), possibly Kernig and/or Brudzinski
  • 13. Divisions of the Neuraxis
    • Cortical Brain
    • Subcortical Brain
    • Brainstem
    • Cerebellum
    • Spinal Cord
    • Root
    • Peripheral Nerve
    • Neuromuscular Junction
    • Muscle
  • 14. Subcortical Brain
    • Deep white radiating fibers produce equal involvement of face/arm/leg
      • weakness
      • sensory abnormalities
    • Visual radiating fibers: (know how visual abnormalities morph with lesions from anterior to posterior brain)
      • deep parietal: bilateral homonomous quad on the floor
      • deep temporal (Meyer’s loop): bilateral homonomous quad in the sky
  • 15. Neurologic Examination when Subcortical Brain is Lesioned
    • Higher Cortical Function : normal
    • Cranial Nerves :
      • visual field cuts
    • Cerebellar Function : usually normal
    • Motor :
      • weakness in face=arm=leg
      • hypertonia
    • Sensory :
      • sensory abnormalities in face=arm=leg
    • Deep Tendon Reflexes :
      • hemi-hyper-reflexia
    • Pathologic Reflexes :
      • Babinski’s reflex if corticospinal tracts are lesioned
      • frontal release signs (nonspecific)
  • 16. Divisions of the Neuraxis
    • Cortical Brain
    • Subcortical Brain
    • Brainstem
    • Cerebellum
    • Spinal Cord
    • Root
    • Peripheral Nerve
    • Neuromuscular Junction
    • Muscle
  • 17. Brainstem
    • CN symptoms characterize BS disease
    • The Brainstem is basically spinal cord with embedded cranial nerves
      • cause symptoms of spinal cord disease, also
      • Long Tract signs: (bilateral and crossed)
        • corticospinal (pyramidal): motor
        • spinothalamic: pain/temp to the thalamus
        • dorsal columns: prioprioception/vibration to thal.
        • (due to decusation of long tracts, BS lesions do not produce horizontal motor/sensory levels as in the cord, but rather vertical levels of hemiparesis/hemidysesthesias)
  • 18. Neurologic Examination when Brainstem is Lesioned
    • Higher Cortical Function : normal
    • Cranial Nerves :
        • III, IV, VI: diplopia
        • V: decreased facial sensation
        • VII: drooping
        • VIII: deaf and dizzy
        • IX, X, XII: dysarthria and dysphagia
        • XI: decreased strength in neck and shoulders
    • Cerebellar Function : usually normal
    • Motor : hemi-paresis (may be crossed), hemi-hypertonia, spasticity
    • Sensory : hemi-dysesthesias (may be crossed)
    • Deep Tendon Reflexes : hemi-hyper-reflexia, brisk jaw jerk
    • Pathologic Reflexes : Babinski’s reflex
  • 19. Divisions of the Neuraxis
    • Cortical Brain
    • Subcortical Brain
    • Brainstem
    • Cerebellum
    • Spinal Cord
    • Root
    • Peripheral Nerve
    • Neuromuscular Junction
    • Muscle
  • 20. Cerebellar Function
    • Some people believe that one can not test specifically for cerebellar abnormalities
      • no one test on examination reliably evaluates the cerebellum
    • H: hypotonia
    • A: assynergy of (ant)agonist muscles
    • N: nystagmus
    • D: dysmetria, dysarthria
    • S: stance and gait
    • T: tremor
  • 21. Neurologic Examination when the Cerebellum is Lesioned
    • Higher Cortical Function : normal
    • Cranial Nerves : usually normal
    • Cerebellar Function :
      • nystagmus
      • flaccid dysarthria
    • Motor :
      • normal bulk and strength with ipsilateral hemi-hypotonia
      • intention worse than positional ipsilateral tremor
      • axial instability with dysmetria
    • Sensory : normal
    • Deep Tendon Reflexes : normal
    • Pathologic Reflexes : normal
      • (plantar flexing to plantar stimulation)
  • 22. Divisions of the Neuraxis
    • Cortical Brain
    • Subcortical Brain
    • Brainstem
    • Cerebellum
    • Spinal Cord
    • Root
    • Peripheral Nerve
    • Neuromuscular Junction
    • Muscle
  • 23. Spinal Cord
    • Sensory level
    • Spasticity/hypertonia
    • Weakness :
      • extensors worse than flexors
      • distal > proximal
    • Bowel and Bladder involvement:
      • retention comes first, then detrusor hyperactivity
      • (both produce incontinence)
  • 24. Neurologic Examination when the Spinal Cord is Lesioned
    • Higher Cortical Function : normal
    • Cranial Nerves : normal
    • Cerebellar Function : normal
    • Motor :
      • weakness (extensors worse than flexors) below the lesion
      • para-hypertonia below the lesion with spasticity
    • Sensory :
      • horizontal level usually lower than the lesion, poorly localizing
      • may be somewhat assymetric
    • Deep Tendon Reflexes :
      • para-hyper-reflexia below the level, possibly clonus
    • Pathologic Reflexes :
      • loss of superficial reflexes (Beavor’s sign, cremasteric, anal wink, etc)
      • Babinski’s reflex
  • 25. Divisions of the Neuraxis
    • Cortical Brain
    • Subcortical Brain
    • Brainstem
    • Cerebellum
    • Spinal Cord
    • Root
    • Peripheral Nerve
    • Neuromuscular Junction
    • Muscle
  • 26. Root/Radiculopathy
    • Pain is the hallmark of a radiculopathy
      • Sensory abnormalities in a dermatome
      • provocative maneuvres exacerbate
      • sharp, stabbing, hot, electric, radiating
    • Weakness in a myotome (assymetric)
      • proximal (C5C6)
      • distal (L5S1)
  • 27. Neurologic Examination when a Root is Lesioned
    • Higher Cortical Function : normal
    • Cranial Nerves : normal
    • Cerebellar Function : normal
    • Motor :
      • assymetric weakness, atrophy, and fasiculations in a myotome
      • tone should be normal, unless multiple roots are severed
    • Sensory :
      • assymetric dysesthesias confined to a dermatome
      • anesthesia requires >1 root transection
    • Deep Tendon Reflexes :
      • hypo- to a-reflexia if the root carries a reflex
    • Pathologic Reflexes :
      • Spurling’s sign
      • dural tension signs may be present (straight leg, crossed straight leg, reverse straight leg, etc)
  • 28. Divisions of the Neuraxis
    • Cortical Brain
    • Subcortical Brain
    • Brainstem
    • Cerebellum
    • Spinal Cord
    • Root
    • Peripheral Nerve
    • Neuromuscular Junction
    • Muscle
  • 29. Peripheral Nerve (presuming nonfocality)
    • Weakness : distal predominant, (a)symetric
    • Sensory Dysesthesias : distal predominant
    • Autonomic involvement may occur
    • Trophic changes : smooth shiny skin, vasomotor abnormalities (edema, temperature dysregulation, vascular flushing), hair loss, nail changes
  • 30. Neurologic Examination with Diffuse PN Lesioning
    • Higher Cortical Function : normal
    • Cranial Nerves :
      • may be abnormal (know which peripheral CN’s associate with specific diseases)
    • Cerebellar Function : normal
    • Motor : weakness is distal predominant if the PN is diffuse
      • atrophy, fasiculations, (hypotonia)
    • Sensory :
      • dysesthesias, anesthesias, hyperpathia, allodynia, etc
    • Deep Tendon Reflexes :
      • distal predominant hypo- to a-reflexia
    • Pathologic Reflexes :
      • mute responses to plantar stimulation
  • 31. Divisions of the Neuraxis
    • Cortical Brain
    • Subcortical Brain
    • Brainstem
    • Cerebellum
    • Spinal Cord
    • Root
    • Peripheral Nerve
    • Neuromuscular Junction
    • Muscle
  • 32. Neuromuscular Junction
    • Fatiguability is the hallmark
    • Weakness : proximal and symmetric
      • exacerbated with use, recovers with rest
      • often affects facial muscles (ptosis, dysconjugate gaze, slack jaw)
      • muscles have normal bulk and tone
    • Sensation : preserved
  • 33. Neurologic Examination in Disorders of the NMJ
    • Higher Cortical Function : normal
    • Cranial Nerves :
      • fatiguability in ptosis, dysconjugate gaze, slack jaw
    • Cerebellar Function : normal
    • Motor :
      • fatiguable proximal weakness in both UE’s and LE’s
      • no atrophy or fasiculations
      • tone may be slightly decreased
    • Sensory :
      • normal, though may complain of lowback pain
    • Deep Tendon Reflexes :
      • may be hypo- to a-reflexic in LEMS
      • may be normal in MG
    • Pathologic Reflexes : none
  • 34. Divisions of the Neuraxis
    • Cortical Brain
    • Subcortical Brain
    • Brainstem
    • Cerebellum
    • Spinal Cord
    • Root
    • Peripheral Nerve
    • Neuromuscular Junction
    • Muscle
  • 35. Muscle
    • Weakness of proximal arm and leg muscles
      • symmetric
    • Sensation is normal
      • though patients complain of cramping, aching, and atrophy
  • 36. Neurologic Examination in Disorders of Muscle
    • Higher Cortical Function : normal
    • Cranial Nerves :
      • ptosis, dysconjugate gaze, slack jaw, bow-string lip, myopathic facies, dysphagia, dysphonia, (dysarthria)
    • Cerebellar Function : normal
    • Motor :
      • usually proximal weakness in both UE’s and LE’s
      • atrophy and fasiculations
      • diffuse hypotonia
      • accentuated primary and secondary curvature, scoliosis
    • Sensory :
      • normal, though may complain of lowback pain
    • Deep Tendon Reflexes : preserved until late in the disease
    • Pathologic Reflexes : ? Myotonia or cramping
  • 37. Just a Few Things to Remember
    • Not all aphasias and apraxias are cortically based
      • thalamus
    • The absence of Babinski’s reflex does not imply a lesion distal to the cord
      • basal ganglia
      • thalamus
      • cerebellum
    • Compromised attention span results from lesioning:
      • brain stem and RAS
      • diencephalon: both sides
      • bilateral cerebral hemispheres
  • 38. Just a Few Things to Remember
    • Some neurologic diseases hit more than one level in the neuraxis
    • The tempo of progression allows one to narrow a differential diagnosis remarkably well . . . Always always always clarify this issue with the patient
    • Parsimony rules
    • Never fabricate part of the exam for sake of being “thorough”
  • 39. Just a Few Things to Remember
    • If you do not think of a complete differential diagnosis, you can not expect to catch the interesting diagnoses.
    • You must think of the possibile accademic diagnoses at this point in your career.
    • Patients pay you to rule out the worst first
    • When you are unsure of a diagnosis, it is important to communicate this to patients and other physicians.