Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
David Roman Renner, MD
                                                                Department of Neurology
           ...
The history and physical accurately localizes most lesions within the
       neuraxis
Divisions of the neuraxis have speci...
Bilateral lesions:
                precentral gyrus: motor homunculous
                supplementary motor cortex: eye and...
Neurologic Examination when Cortical Brain is Lesioned
      Higher Cortical Function: you may see an aphasia, apraxia, or...
Neurologic Examination when Brainstem is Lesioned
      Higher cortical function should be normal
      Cranial nerves may...
Motor exam reveals bilateral leg weakness (extensors worse than flexors) below
              the lesion with increased ton...
Neurologic Examination with Diffuse Peripheral Nerve Lesioning
      Higher cortical function should be normal
      Crani...
Upcoming SlideShare
Loading in …5
×

Cortical Localization

3,524 views

Published on

  • Be the first to comment

Cortical Localization

  1. 1. David Roman Renner, MD Department of Neurology 10:00 October 21, 2002 Cortical Localization Reading Resources: Lindsay KW, Bone I, Callander R. Clinical Presentation, Anatomical Conceps and Diagnostic Approach: Higher Cortical Dysfunction. In: Neurology and Neurosurgery Illustrated. Philadelphia, Churchill Livingstone 1998, pp. 105-114. Rolak LA. Approach to the Patient with Neurologic Disease. In: Neurology Secrets. Philadelphia, Hanley & Belfus, Inc. 1993, pp. 37-44. What you are responsible for: I will write all test questions for this lecture hour, the content of which is addressed in this handout and/or the lecture hour. Your test questions will only be derived from the section on cortical localization. The remaining text is included to assist you in localizing lesions in the neuraxis through a complete neurologic examination. Syllabus Contents: Divisions of the Neuroaxis Content of the Neurologic Examination Clinical Hallmark of Lesions within the Neuraxis Typical Neurologic Examination when Lesioning Various Levels of the Neuraxis Objectives: The student should be able to: 1. state how hemispheric dominance is defined 2. lateralize hemispheric dominance based upon language and handedness 3. localize lesions within the hemispheric cortex via clinical exam findings (You will not be tested on information following the cortical localization section.)
  2. 2. The history and physical accurately localizes most lesions within the neuraxis 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 Divisions of the Neuraxis: Cortical Brain Subcortical Brain Brainstem Cerebellum Spinal Cord Root Peripheral Nerve Neuromuscular Junction Muscle The neurologic exam allows one to accurately identify which segment of the neuraxis is lesioned. A complete neurologic exam varies between neurologists, but generally consists of testing of: Higher cortical function Cranial nerves Cerebellar Motor Sensory Reflexes Gait and Station Higher Cortical Function: Depends upon hemispheric dominance Non-neurologists are able to state generalizations about hemispheric dominance: right: visual/spatial, perception and memory left: language and language dependent memory One should be able to further localize lesions Cortical Brain: Frontal Lobe: Left sided lesions: language Broca’s Aphasia Right sided lesions: ?judgement?
  3. 3. Bilateral lesions: precentral gyrus: motor homunculous supplementary motor cortex: eye and head turn prefrontal cortex: personality, initiative paracentral lobule: cortical inhibition of voiding B/B Parietal Lobe: Right sided lesions: anosognosia: left hemineglect dressing and constructional apraxia geographic agnosia Left sided lesions: Gerstman’s Tetrad (not triad): L/R confusion, finger agnosia, acalculia, agraphia without alexia Bilateral lesions: Somatosensory homunculous abnormal posture and passive movement localization of touch 2-point discrimination astereognosis Temporal: Right sided lesions: hearing language Left sided lesions: hearing sounds, rhythm, music Wernicke’s Aphasia Bilateral lesions: learning and memory: mid/inferior gyri olfaction: limbic Auditory cortex: Heschel’s gyrus Occipital Lobe: Right sided lesions: micropsia macropsia Left sided lesions: ? Bilateral lesions: visual hallucinations: elemental and unformed prosopagnosia: familiar faces cortical blindness: striate cortices, normal pupil rx Anton’s syndrome: (para)striate, denial of obvious blindness Balint’s syndrome: inability to direct voluntary gaze with visual agnosia
  4. 4. Neurologic Examination when Cortical Brain is Lesioned Higher Cortical Function: you may see an aphasia, apraxia, or an agnosia Cranial Nerves should be normal, unless there is forced eye deviation Cerebellar function should be normal Motor exam may reveal weakness of face/arm>leg (or vice versa) with hypertonia if corticospinal tracts are hit Sensory exam may be abnormal (face/arm>leg, or vice versa) Reflexes may be abnormal (hyper-reflexia), and Babinski’s reflex may be present if the corticospinal tracts are hit Subcortical Brain Contains deep white radiating fibers tightly packed together When lesioned, there is equal involvement of face/arm/leg. Symptoms can include weakness or sensory abnormalities Visual abnormalities occur due to interruption of radiating fibers are contained within the subcortical brain deep parietal: bilateral homonomous quad on the floor deep temporal (Meyer’s loop): bilateral homonomous quad in the sky Neurologic Examination when Subcortical Brain is Lesioned Higher cortical function should be normal Cranial nerves may reveal a visual field cut Cerebellar function is usually normal Motor exam may reveal weakness in face=arm=leg with hypertonia Sensory exam may reveal sensory abnormalities in face=arm=leg Reflexes may be abnormal (hyper-reflexia) with increased tone, and Babinski’s reflex may be present if corticospinal tracts are lesioned Brainstem The brainstem is basically a spinal cord with embedded cranial nerves Cranial nerve symptoms with long tract symptoms characterize brainstem disease 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)
  5. 5. Neurologic Examination when Brainstem is Lesioned Higher cortical function should be normal Cranial nerves may be abnormal 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 should be normal Motor exam may reveal hemi-paresis and hemi-hypertonia Sensory exam may reveal sensory abnormalities Reflexes may be abnormal (hyper-reflexia) including the jaw jerk reflex, with increased tone, and Babinski’s reflex Cerebellar Function Some people believe that one can not test specifically for cerebellar abnormalities no single 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 Neurologic Examination when the Cerebellum is Lesioned Higher cortical function should be normal Cranial nerves should be normal Cerebellar function may reveal nystagmus, flaccid dysarthria Motor exam should show preserved strength, with ipsilateral hypotonia, an ataxic tremor, dysmetria Sensory exam should be normal Reflexes should be normal Spinal Cord Sensory level Spasticity/hypertonia almost always in the legs, sometimes in the arms if the lesion is high enough Weakness in the legs, extensors > than flexors, distal > proximal Bowel and bladder involvement producing incontinence Neurologic Examination when the Spinal Cord is Lesioned Higher cortical function should be normal Cranial nerves should be normal Cerebellar function should be normal
  6. 6. Motor exam reveals bilateral leg weakness (extensors worse than flexors) below the lesion with increased tone/spasticity Sensory exam reveals a sensory level which may be assymetric Reflexes are increased (hyper-reflexic) below the level (clonus?) With Babinski’s reflex, and the loss of superficial reflexes (Beavor’s sign, cremasteric, anal wink, etc) Root/Radiculopathy Pain is the hallmark of a radiculopathy Sensory abnormalities should localize to a dermatome provocative maneuvres exacerbate the discomfort Asymmetric weakness in a myotome proximal (C5C6) distal (L5S1) (because the most common radiculopathy in the cervical region produces proximal weakness, and the most common radiculopathy in the lumbosacral region produces distal weakness, one cannot make the statement that radiculopathies “tend to produce proximal/distal weakness.” Neurologic Examination when a Root is Lesioned Higher cortical function should be normal Cranial nerves should be normal Cerebellar function should be normal Motor exam may reveal assymetric weakness, atrophy, and fasiculations in a myotome Sensory exam may reveal assymetric dysesthesias confined to a dermatome Reflexes may be decreased (hypo- to a-reflexia if the root carries a reflex) Peripheral Nerve (nonfocal) Weakness that is distal predominant, which may start a bit asymmetric, but with time, looks symmetric Sensory dysesthesias that are distal predominant Autonomic involvement may occur Difficulty focusing eyes Erectile dysfunction Dyshydrosis: changes in the pattern of sweating Constipation Cardiac arrhythmias Trophic changes: smooth shiny skin, vasomotor abnormalities (edema, temperature dysregulation, vascular flushing), hair loss, nail changes
  7. 7. Neurologic Examination with Diffuse Peripheral Nerve Lesioning Higher cortical function should be normal Cranial nerves should be normal Cerebellar function should be normal Motor exam may reveal distal-predominant weakness, atrophy, and fasiculations Sensory exam may reveal distal-predominant sensory loss Reflexes may reveal distal hypo- to a-reflexia 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 Neurologic Examination in Disorders of the Neuromuscular Junction Higher cortical function should be normal Cranial nerves may show fatiguable ptosis, dysconjugate gaze, slack jaw Cerebellar function should be normal Motor exam may reveal fatiguable proximal weakness in both UE’s and LE’s no atrophy or fasiculations tone may be slightly decreased Sensory exam should be normal Deep tendon reflexes may be hypo- to a-reflexic in Lambert Eaton Myasthenic Syndrome, or normal in MG Muscle Symmetric proximal weakness of arm and leg muscles Sensation is normal (though patients complain of cramping and aching) Neurologic Examination in Disorders of Muscle Higher cortical function should be normal Cranial nerves may reveal nonfatiguable ptosis, dysconjugate gaze, slack jaw, dysphagia, dysphonia, (dysarthria) Cerebellar function should be normal Motor exam reveals symmetric proximal weakness in both UE’s and LE’s atrophy and fasiculations Sensory exam should be normal Reflexes should be preserved until late in the disease

×