Frontal Lobe Syndromes

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Frontal Lobe Syndromes

• Katalin Gyömörey, Ph.D., M.D.

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Outline

• Functional anatomy of the frontal lobes
• Neurotransmitters in the frontal lobes
• Deficits resulting from frontal lobe insult
• Testing prefrontal cortical function
• Common causes of frontal lobe syndromes

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Functional Frontal Lobe Anatomy

• Largest of all lobes
• SA 1/3 / hemisphere
• 3 major areas in each lobe
• Dorsolateral aspect
• Medial aspect
• Inferior orbital aspect

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Functional Frontal Lobe Anatomy
Primary motor area
Premotor area
B4
B6
Central sulcus
Supplementary motor area
(medially)
Frontal eye field
B 8
Prefrontal area
B 9, 10, 11, 12
Lateral sulcus/ Sylvian fissure
Motor speech area of Broca
B 44, 45
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Functional Frontal Lobe Anatomy

• Motor cortex
• Primary
• Premotor
• Supplementary
• Frontal eye field
• Brocas speech area

• Prefrontal cortex
• Dorsolateral
• Medial
• Orbitofrontal

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Motor Cortex

• Primary motor cortex
• Input thalamus, BG, sensory, premotor
• Output motor fibers to brainstem and spinal cord
• Function executes design into movement
• Lesions?/? tone ? power ? fine motor function
  on contra lateral side

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Motor Cortex

• Premotor cortex
• Input thalamus, BG, sensory cortex
• Output primary motor cortex
• Function stores motor programs controls coarse
  postural movements
• Lesions moderate weakness in proximal muscles on
  contralateral side

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Motor Cortex

• Supplementary motor
• Input cingulate gyrus, thalamus, sensory
  prefrontal cortex
• Output premotor, primary motor
• Function intentional preparation for movement
  procedural memory
• Lesions mutism, akinesis speech returns but it
  is non-spontaneous

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Motor Cortex

• Frontal eye fields
• Input parietal / temporal (what is target)
  posterior / parietal cortex (where is target)
• Output caudate superior colliculus paramedian
  pontine reticular formation
• Function executive selects target and commands
  movement (saccades)
• Lesion eyes deviate ipsilaterally with
  destructive lesion and contralaterally with
  irritating lesions

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Motor Cortex

• Brocas speech area
• Input Wernickes
• Output primary motor cortex
• Function speech production (dominant
  hemisphere) emotional, melodic component of
  speech (non-dominant)
• Lesions motor aphasia monotone speech

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Prefrontal Cortex

• Orbital prefrontal cortex
• Connections temporal,parietal, thalamus, GP,
  caudate, SN, insula, amygdala
• Part of limbic system
• Function emotional imput, arousal, suppression
  of distracting signals
• Lesions emotional lability, disinhibition,
  distractibility, hyperkinesis

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Prefrontal Cortex

• Dorsomedial prefrontal cortex
• Connections temporal,parietal, thalamus,
  caudate, GP, substantia nigra, cingulate
• Functions motivation, initiation of activity
• Lesions apathy decreased drive/ awareness/
  spontaneous movements akinetic-abulic syndrome
  mutism

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Prefrontal Cortex

• Dorsolateral prefrontal cortex
• Connections motor / sensory convergence areas,
  thalamus, GP, caudate, SN
• Functions monitors and adjusts behavior using
  working memory
• Lesions executive function deficit disinterest
  / emotional reactivity ? attention to relevant
  stimuli

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Neurotransmitters

• Dopaminergic tracts
• Origin ventral tegmental area in midbrain
• Projections prefrontal cortex (mesocortical
  tract) and to limbic system (mesolimbic tract)
• Function reward motivation spontaneity arousal

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Neurotransmitters

• Norepinephrine tracts
• Origin locus ceruleus in brainstem and lateral
  brainstem tegmentum
• Projections anterior cortex
• Functions alertness, arousal, cognitive
  processing of somatosensory info

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Neurotransmitters

• Serotonin tracts
• Origin raphe nuclei in brainstem
• Projections number of forebrain structures
• Function minor role in prefrontal cortex sleep,
  mood, anxiety, feeding

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Frontal Lobe Syndromes The Case of Phineas Gage
(Harlow 1868)

• tamping iron blown through skull L frontal brain
  injury
• excellent physical recovery
• dramatic personality change no longer
  Gagestubborn, lacked in consideration for
  others, had profane speech, failed to execute his
  plans

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Frontal Lobe Syndromes

• Emotional make-up and personality
• Abstraction and judgment
• Attention and memory
• Language

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Frontal Lobe Syndromes

• Emotional make-up and personality
• May be the only manifestation
• Apathy / euphoria / labile mood
• Decreased drive / poor impulse control
• Abulia akinetic mutism
• Pseudobulbar palsy Opercular syndrome
• Best assessed with Hx from family / friends
  observation

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Frontal Lobe Syndromes

• Abstraction and judgment
• Cognitive functions undisturbed
• Concrete thinking
• Diminished insight
• Defect in planning / executive control

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Frontal Lobe Syndromes

• Tests of abstraction and judgment
• Interpret proverbs (e.g.the golden hammer opens
  iron doors)
• Explain why conceptually linked words are the
  same (e.g. coat skirt)
• Plan structure a sequential set of activities
  (how would you bake a cake?)
• Insight / reaction to own illness

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Frontal Lobe Syndromes

• Attention and memory
• Inattentiveness
• Defect in working memory
• Defect in sequencing, perseverance

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Frontal Lobe Syndromes

• Tests of attention and memory
• Alternative sequence (e.g. copying MNMN)
• Lurias fist-edge-palm test (show 3X)
• Go/no-go
• tap once if I tap twice, dont tap if I tap
  once
• tap for A
• read 60 letters at 1/sec N lt 2 errors

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Frontal Lobe Syndromes

• Tests of attention and memory cont
• Digit span
• repeat 3-52 3-52-8 3-52-8-67.. N gt5
• Visual grasp look away from stimulus
• Recency test
• recall sequence of stimuli / events
• Imitation (of examiner) / utilization (of
  objects presented)

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Frontal Lobe Syndromes

• Language
• Brocas / non-fluent aphasia
• Prefrontal/ transcortical motor aphasia
• Language-motor dissociation
• Akinetic mutism

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Frontal Lobe Syndromes

• Language tests
• Thurstone / word fluency test (recite as many
  words beginning with F in 1 min as you can,
  then with A, S) N gt15
• Repetition (Brocas vs transcortical)
• Ball
• Methodist
• Methodist episcopal
• No ifs ends or buts
• Around the rugged rock the ragged rascal ran

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Frontal Lobe Syndromes

• Formal Tests
• Wisconsin Card Sorting Test
• abstract thinking and set shifting LgtR
• Trail Making
• visuo-motor track, conceptualization, set shift
• Stroop Color Word Test
• attention, shift sets LgtR
• Tower of London Test
• planning

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Wisconsin Card Sorting Test
Please sort the 60 cards under the 4 samples. I
wont tell you the rule, but I will announce
every mistake. The rule will change after 10
correct placements.
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Trail Making Test
5
B
A
4
6
C
1
2
D
3
7
Various levels of difficulty 1. Please connect
the letters in alphabetical order as fast as you
can. 2. Repeat, as in 1 but alternate with
numbers in increasing order
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Stroop Color and Word Tests
RED BLUE ORANGE YELLOW GREEN RED PURPLE
RED GREEN YELLOW BLUE RED YELLOW ORANGE RED
GREEN BLUE GREEN PURPLE RED
Please read this as fast as you can
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Tower of London Tests
Various levels of difficulty e.g. Please
rearrange the balls on the pegs, so that each peg
has one ball only. Use as few movements as
possible
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Diseases Commonly Associated With Frontal Lobe
Lesions

• Traumatic brain injury
• Gunshot wound
• Closed head injury
• Widespread stretching and shearing of fibers
  throughout
• Frontal lobe more vulnerable
• Contusions and intracerebral hematomas

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Diseases Commonly Associated with Frontal Lobe
Lesions

• Frontal Lobe seizures
• Usually secondary to trauma
• Difficult to diagnose can be odd (laughter,
  crying, verbal automatism, complex gestures)

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Diseases Commonly Associated With Frontal Lobe
Lesions

• Vascular disease
• Common cause especially in elderly
• ACA territory infarction
• Damage to medial frontal area
• MCA territory
• Dorsolateral frontal lobe
• ACom aneurysm rupture
• Personality change, emotional disturbance

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Diseases Commonly Associated With Frontal Lobe
Lesions

• Tumors
• Gliomas, meningiomas
• subfrontal and olfactory groove meningiomas
  profound personality changes and dementia
• Multiple Sclerosis
• Frontal lobes 2nd highest number of plaques
• euphoric/depressed mood, Memory problems,
  cognitive and behavioral effects

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Diseases Commonly Associated With Frontal Lobe
Lesions

• Degenerative diseases
• Picks disease
• Huntingtons disease
• Infectious diseases
• Neurosyphilis
• Herpes simplex encephalitis

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Diseases Commonly Associated with Frontal Lobe
Lesions

• Psychiatric Illness proposed associations
• Depression
• Schizophrenia
• OCD
• PTSD
• ADHD

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Frontal Lobe Syndromes Summary

• Personality and emotional changes
• Reflect prefrontal lesions
• Role of Dopamine and Norepinephrine
• Trauma gt vascular, tumors

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Functional Frontal Lobe Anatomy

• Five frontal subcortical circuits
  (Cummings,93)
• Motor
• Oculomotor
• Dorsolateral prefrontal
• Lateral orbitofrontal
• Anterior cingulate

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Functional Frontal Lobe Anatomy

• Frontal subcortical circuits

Globus Pallidus Substantia Nigra
Thalamus DM CM nuclei
Striatum Caudate Putamen
Frontal cortex
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Frontal subcortical Circuits 1. Motor Circuit

• Supplementary Motor Premotor planning,
  initiation storage of motor programs
  fine-tuning of movements
• Motorfinal station for execution of the the
  movement according to the design

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Frontal subcortical Circuits 2. Oculomotor
Circuit

• Voluntary scanning eye movement
• Independent of visual stimuli

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Frontal subcortical Circuits 3. Dorsolateral
Prefrontal Circuit

• Executive functions motor planning, deciding
  which stimuli to attend to, shifting cognitive
  sets
• Attention span and working memory

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Frontal subcortical Circuits 4. Lateral
Orbitofrontal Circuit

• Emotional life and personality structure
• Arousal, motivation, affect
• Orbitofrontal cortex consciousness

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Frontal subcortical Circuits 5. Anterior
Cingulate Circuit
MD Thalamus

• Abulia, akinetic mutism