Frontal Lobe Brain Injury

Introduction[edit | edit source]

In evolutionary terms the frontal cortex has been the most recent to evolve, and the frontal lobes are the area of brain which has developed greatly in humans, differentiating us from other mammals. These lobes integrate the other brain areas, and are particularly responsible for higher level thinking and cognitive skills such as planning, evaluating likely outcomes, multitasking, performing risk assessment and the niceties of social interaction; it is the area of brain which deals in abstract concepts.

Anatomy
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The Frontal Lobes account for approximately one third of human brain mass.

Frontal lobe animation.gif

They lie at the front of the brain, anterior to the parietal lobes and superior to the temporal lobe.

Each frontal lobe (left and right) is generally considered to have several distinct divisions:

  • Motor cortex
  • Premotor cortex
  • Supplementary motor cortex
  • Prefrontal cortex
  • Orbital cortex AKA frontal eye fields
  • Broca's Area

Vascular Supply[edit | edit source]

Medial frontal lobe = anterior cerebral artery

Deep & lateral regions = superior division of middle cerebral artery

Function
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Author Mesulam suggests that the frontal lobe is the part of the brain which modifies and imposes constraints on reflexive behaviours[1], and this control develops as the infant brain grows[2] and the frontal lobes become larger and more active.

  • Motor cortex = voluntary movement
  • Premotor cortex = storage of motor patterns & voluntary activities
  • Prefrontal cortex = ability to concentrate; inhibition of reflexive behaviours; personality & emotional traits; abstract thinking
  • Broca's Area = Motor control of speech    

Primary Motor Cortex[edit | edit source]

Input: Basal gangliam thalamus, premotor cortex (in the frontal lobe), sensory cortex (in the parietal lobe)
Output: Motor fibres to spinal cord and brainstem, travelling in the corticospinal tract
Function: Movement

Pre motor Cortex[edit | edit source]

Input: Basal ganglia, thalamus, sensory cortex

Output: Primary motor cortex

Function: storage of motor programs, sensorimotor integration, facilitation of controlled, smooth movements

Supplementary Motor Cortex[edit | edit source]

Input: Thalamus, cingulate gyrus, sensory & prefrontal cortex

Output: Premotor cortex, primary motor cortex

Function: Intentional preparation for movement, procedural memory

Prefrontal Cortex[edit | edit source]

Function: working memory, executive functions including the ability to plan & implement (& monitor/evaluate) a series of goal-directed actions.

Frontal Eye Fields[edit | edit source]

Input: Parietal cortex, temporal cortex

Output: Caudate, superior colliculus, paramedian pontine reticular formation

Function: Control of voluntary scanning movements of the eye

Broca's Speech Area[edit | edit source]

Input: Wernicke's area

Output: Primary motor cortex

Function: Dominant hemisphere = speech production.  Non-dominant hemisphere = emotional & melodic component of speech

Pathology/Injury - Symptoms
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It has been found that in traumatic brain injury contusions typically occur on the poles and the inferior aspects of the frontal lobes[3].

Disturbances of Motor Function[edit | edit source]

  • Loss of fine  movements, strength & speed  [damaged area = primary motor cortex]
  • Changes in voluntary gaze  [damage to frontal eye field]
  • Changes in speech  [damaged area = Broca's speech area), usually slow, hesitant speech, difficulties in word finding, perseveration

3 Frontal Lobe Syndromes[edit | edit source]

Orbitofrontal syndrome = lack of inhibition

Frontal convexity syndrome = apathetic

Medial frontal syndrome = akinetic

Orbitofrontal syndrome[edit | edit source]

Patient demonstrates disinhibited, impulsive behaviour; difficulty in controlling their emotions; difficulty in maintaining concentration; lacking in judgement; failure to appreciate/anticipate consequences of their actions; can show euphoria, hypomania or grandiosity.

Orbitofrontal damage can also lead to abnormal sexual behaviour.

Frontal convexity syndrome[edit | edit source]

Patient shows disinterest and is apathetic; slowing of motor functions; unable to plan ahead; lacks motivation; lacks concern about the world around them.  

Medial frontal syndrome[edit | edit source]

Reduced movement; loss of sensation in lower limbs; urinary incontinence; occasional mutism; profound apathy; sometimes show indifference to thirst or hunger

Resources[edit | edit source]

Recent Related Research (from Pubmed)[edit | edit source]

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References[edit | edit source]

References will automatically be added here, see adding references tutorial.

  1. Mesulam MM. DT Stuss and RT Knight. The Human Frontal Lobes: Transcending the Default Mode through Continent Encoding. Principles of Frontal Lobe Function. Oxford: 2002. 8-30
  2. Luciana, ed. by Charles A. Nelson. Handbook of developmental cognitive neuroscience. Monica (2001). Cambridge, Mass. [u.a.]: MIT Press.
  3. Flint AC, Manley GT, Gean AD, et al. Post-operative expansion of hemorrhagic contusions after unilateral decompressive hemicraniectomy in severe traumatic brain injury. J Neurotrauma. Mar 17 2008