The Frontal Lobes: An approach Mark Keezer R4 Neurology Dec 1, 2010
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Transcript of The Frontal Lobes: An approach Mark Keezer R4 Neurology Dec 1, 2010
In a famous incident in 1848, Mr Phineas Gage, a 25-year-old railroad worker, sustained severe damage to his frontal lobes when a metal tamping rod was blasted through his head after a freak accident...
Gage`s accidental frontal lobotomy laid some of the groundwork for the surgical procedure of frontal (prefrontal) lobotomy...
This operation became popular in the mid-twentieth century; it was done extensively over a period of years not only for psychosis but also for neurosis and depression... recommended for “difficult children”.
Multiple Divisions of the Frontal Lobe
• Motor cortex• Premotor & Supplementary Motor cortex
• Apraxia• Frontal Eye Fields• Broca’s Area.
The Remainder
• Prefrontal Cortex– Orbitofrontal Cortex (OFC)– Medial Prefrontal Cortex (MPC)– Dorsolateral Prefrontal Cortex (DLPFC).
To begin with...
Sustained Attention• Digit span (7 forward, 4 backward)• Serial 7’s• WORLD• Months/days of the week backwards.
Orbitofrontal Cortex
• Disorder of Social Conduct (right hemisphere)– Dis-inhibited, impulsive behaviour– Poor hygiene, promiscuity, spending money– Poor judgement and insight– Emotional lability– Euphoria– Witzelsucht (transl: joke addiction)
– Facetiousness, inappropriate levity and senseless joking.
Medial Prefrontal Cortex (including Cingulate Cortex)
• Akinetic/apathetic/abulic syndrome– Paucity of spontaneous movement and gesture– Sparse verbal output
• Repetition may be preserved• Urinary (& fecal) incontinence
– Micturition centre.
Frontal Gait Disorder (perhaps more MPC)
• “...the disorder represents a loss of integration, at the cortical and basal ganglionic levels, of the essential instinctual elements of stance and locomotion that are acquired in infancy...”
• Short-stride, shuffling, hesitant steps
• Magnetic gait– Ignition apraxia
• Turning by small steps with one foot, the other planted as a pivot
• Retropulsion.
Dorsolateral Prefrontal Cortex
• Dysexecutive syndrome– Ability to plan, monitor, and carry out an
activity to achieve a goal
– Poor judgement
– Indifference (almost “la belle…”).
Dorsolateral Prefrontal Cortex
• On exam– Abstract thought (orange & apple, chair & table, watch
& ruler, tree & ant)
– Judgment
– “You arrive in Vancouver, you’ve lost your friend’s phone number and they are not listed in the phone book. How do you find them?”
– Executive function
– Perseveration due to difficulty abandoning the initial pattern of responses.
Executive Function• Go-no-go (inhibitory control; 1=2, 2=0)
• Conflicting instructions (sensitivity to interference; 1=2, 2=1)
• Louria sequences (fist, edge, palm)
• Lexical fluency (>11 words in 1 minute = normal)
• Trails
• Clock drawing
• Stroop test
• String of M’s and N’s
• Applause sign.
GLASS
TLCC
Frontal Release Signs (perhaps more DLPFC)
• Palmar grasp– Don’t warn them, just lay their hands down and touch then and see if they
hold your hands spontaneously
• Glabellar tap (Meyerson’s sign)
• Palmomental reflex (the only with localization value)
• Snout reflex
• Rooting reflex
• Utilization behaviour
• Echolalia & Echopraxia.
A popular procedure was the “ice-pick” lobotomy in which an ice pick was inserted above the eye and pounded through the orbital roof with a mallet, then swept to and fro...
The primary proponent of this technique used a gold-plated ice pick and kept speed records for the procedure. A lobotomy was once done on an eccentric actress who had no mental illness... The procedure has been abandoned.