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Lessons from the Works of Oliver Sacks
FUNCTIONAL CORRELATES OF
GYRAL ANATOMY
S Wright | RT Fitzgerald
eEdE-19
Disclosures
I have no commercial interests to disclose.
Purpose and Methods
Purpose: This presentation will review specialized areas of
the cerebral cortex and their associated functions and
illustrate the importance of familiarity with this topic.
Methods: We will draw from the prolific works of Oliver
Sacks to show clinical correlation of anatomy and function.
Lastly, image-based cases will highlight real-life scenarios.
How is this helpful?
• Radiologists can feel removed from what “abnormal
signal” in a brain can mean for a patient.
• Being familiar with how lesions present can help with
communication between radiologists and clinical
colleagues.
• With the aid of a focused clinical history and neurological
examination, specific areas can be scrutinized more
closely, increasing our sensitivity for subtle findings.
Oliver Sacks
•
British Neurologist 1933-2015
•
Prolific writer of lay and
academic neurologic casebased literature, much of which
focuses on correlation of
clinical presentation with lesion
localization
•
“Poet laureate of contemporary
medicine.” – The New York
Times
The Cerebrum
•
The cerebrum arises from
the embryonic
telencephalon
•
This is the “newest” portion
of the central nervous
system, in terms of
evolutionary development.
Case courtesy of Dr Jeremy Jones,
Radiopaedia.org, rID: 36277
Cerebral Cortex
Hagmann P, et al.
Highly specialized infoldings of the cerebrum correlate
with physical, emotional, and mental functioning.
Frontal Lobe Gyri
Lateral surface: Superior, middle
and inferior frontal gyri, precentral
gyrus, opercular gyrus, and
premotor area
Orbital surface: Orbital (lateral,
anterior, posterior, medial) gyri,
gyrus rectus
Medial surface: Paracentral lobule,
cingulate gyrus
S. Lamb. Rice University
Temporal Lobe Gyri
Lateral surface:
Superior, middle, and
inferior temporal gyri
Basal surface:
Occipitotemporal
gyrus
S. Lamb. Rice University
Medial Temporal Lobe
Takahashi T, et al. 2006
The medial temporal lobe
is part of the limbic
system and includes the
uncus, parahippocampal
gyrus, and fusiform gyrus.
Parietal Lobe Gyri
Lateral Surface:
Postcentral gyrus,
superior parietal lobule,
inferior parietal lobule
(supramarginal and
angular gyri)
Medial surface:
Paracentral lobule,
precuneus
S. Lamb. Rice University.
Occipital Lobe Gyri
Lateral surface:
Superior, middle,
and inferior
occipital gyri
Medial surface:
Cuneus, lingual
gyrus
Medial Cortical Surface
Frontal Lobe Functions
General functions of the frontal lobe include executive
decision-making and social behavior.
More specialized regions include the precentral gyrus,
which controls contralateral motor function and Broca’s
area which controls speech motor activity in the dominant
hemisphere.
Case from Oliver Sacks
“Mrs. B.”, a research chemist, presented with a rapid
personality change. She became “funny,” “facetious,”
“impulsive-and superficial.”
A friend says, “She no longer seems to care about anything
at all.”
The initial working diagnosis was hypomania, but search for
an organic cause was performed.
Excerpt from “Yes, Father-Sister” in The
Man Who Mistook His Wife for a Hat
“Her face bore no deeper expression whatever. Her
world had been voided of feeling and meaning.
Nothing any longer felt ‘real’ (or ‘unreal’). Everything
was now ‘equivalent’ or ‘equal’-the whole world
reduced to a facetious insignificance.”
Diagnosis
Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 8861
“At first it was thought that she
might be hypomanic, but she
turned out to have a cerebral
tumour. At craniotomy there was
found, not a meningioma as had
been hoped, but a huge
carcinoma involving the
orbitofrontal aspects of both
frontal lobes.”
T2W image of esthesioneuroblastoma
infiltrating into the orbitofrontal cerebrum.
Temporal Lobe Functions
The lateral temporal lobe includes, among others,
specialized areas for auditory processing, as well as
Wernicke’s area for comprehension of spoken language.
The medial temporal lobe contains many structures of the
limbic system, which controls emotion, behavior, olfactory
processing, and memory.
Case from Oliver Sacks
“Mrs. O’C”, a nursing home resident, complained of sudden
onset of persistently playing music, which she originally thought
was due to a record player being turned on at the residence.
Consultation with ENT and psychiatry was obtained before
neurology consultation with Dr. Sacks.
Excerpt from “Reminiscence” in The Man
Who Mistook His Wife for a Hat
“One night, in January 1979, she dreamt vividly,
nostalgically, of her childhood in Ireland, and
especially of the songs they danced to and sang.
When she woke up, the music was still going, very
loud and clear.”
Diagnosis
Di Pietro M, et al.
“I obtained a brainscan, and this
showed that she had indeed had
a small thrombosis…in part of
her right temporal lobe. The
sudden onset of Irish songs in
the night, the sudden activation
of musical memory-traces in the
cortex, were, apparently, the
consequence of a stroke, and as
it resolved, so the songs
‘resolved’ too.”
Images demonstrate infarct involving the
superior temporal gyrus. This patient had
musical deficits, as opposed to positive musical
symptoms.
Parietal Lobe Functions
Specialized functions
of the parietal lobe
include sensation and
spatial perception.
Example of a drawing of a clock in
patient with hemineglect syndrome
from a unilateral parietal lesion
Know the Central Sulcus!
• It divides the precentral gyrus of the
frontal lobe from the postcentral gyrus
of the parietal lobe
• These are known as the primary
motor and sensory strips, respectively
• Localized lesions along these gyri
present in very predictable manners.
Case courtesy of A.Prof Frank Gaillard,
Radiopaedia.org, rID: 33834
Case from Oliver Sacks
A patient on the neurology ward for a pre-existing
condition awoke without sensation of one of his legs;
further, the patient did not recognize the leg as
belonging to him.
Excerpt from “The Leg”
“I suddenly remembered a patient on the Neurology Wards 15
years before, who had woken from sleep, one Christmas Day, to
find ‘a strange leg’ in his bed. There was a Christmas party
going on, and the only ‘explanation’ he could imagine was that
one of the nurses, as a joke, had filched a leg from the Anatomy
Room, and slipped it under the covers as he slept. Amused, and
disgusted, he threw ‘the damn thing’ out of the bed, but then
found, to his inexpressible amazement and horror, that he came
out with it, that ‘the damn thing’ was attached to him.”
Diagnosis
OpenStax College - Anatomy & Physiology, Connexions Web site.
“It turned out that he had a
tumour of the right parietal lobe
of his brain, which had
haemorrhaged while he was
snoozing on Christmas Day,
obliterating the ‘leg area’ of the
brain, and thus obliterating any
sense of his own leg, so that,
when he ‘discovered’ it, it was
not his, but ‘a damn thing’.”
Sensory Homunculus
Homunculus
Different parts of the body are located at very specific
locations of the motor and sensory strips.
The homunculus is a visual representation of body parts
mapped onto the structures of the correlating cortex
responsible for their sensory or motor functions.
Occipital Lobe Functions
Dr. Nisreen Abo-Elmaaty
The occipital lobe receives the input from the optic
system and is responsible for visual processing.
Oliver Sacks Case
“Rosalie”, a 90 year old woman, completely blind from
acquired retinal damage, presented with vivid and complex
visual hallucinatory scenes which persist for long periods of
time.
The patient was seen by a psychiatrist who found no mental
disease. A neurology consultation was requested, and she
was seen by Dr. Sacks.
Excerpt from Hallucinations
“I observed with Rosalie (as with many other
patients) that while she was hallucinating, her eyes
were open, and even though she could see
nothing, her eyes moved here and there, as if
looking at an actual scene.”
Diagnosis
National Eye Institute of the NIH
“I explained to her that hallucinations, strangely,
are not uncommon in those with blindness or
impaired sight, and that these visions are not
“psychiatric” but a reaction of the brain to the loss
of eyesight. She had a condition called Charles
Bonnet syndrome.”
CBS patients have been shown to have aberrant
occipital lobe uptake on FDG-PET, and it is
theorized this is due to deafferentiation, or loss of
input, to the visual cortex of the occipital lobe.
Fundoscopic image demonstrating
changes of macular degeneration
Case 1
The patient is a 60 year old male with history of
chest wall melanoma, negative margins at
resection.
A year later, patient presents with acute left-sided
weakness.
Imaging was obtained at presentation.
SWI
FLAIR
Case 1
The SWI and FLAIR images show a large, hemorrhagic
melanoma lesion in the high right frontal lobe with a large
amount of adjacent edema.
The mass effect compresses the patient’s motor strip,
thereby resulting in the left-sided motor deficits seen on
examination.
While not a small or subtle lesion, this case shows good
clinical and imaging correlation.
Case 2
A 32 year old, otherwise healthy female
presents with persistent auditory
hallucinations.
Schizophrenia is the working diagnosis, but a
search for an organic cause is performed.
FLAIR
T1 +C
Case 2
The preceding axial and coronal images show a
FLAIR hyperintense, non-enhancing mass in the
superior temporal gyrus, which contains the primary
auditory cortex.
The low-grade glioma was resected, and the
hallucinations resolved.
Case 3
A 45 year old male presents for evaluation of
right inferior quadrantanopia.
Further history reveals recent ataxia and
cognitive decline.
DWI
Case 3
The preceding axial DWI slice shows restricted diffusion
involving the left occipital cortex.
With other testing, the diagnosis of Creutzfeldt-Jakob disease
was made.
The location of the cortical signal abnormality correlates with
the patient’s isolated right visual field deficit. The diagnosis of
CJD is also consistent with other components of the patient’s
presentation.
Summary
Radiologists are good at thoroughly reviewing images, but
knowing where to look can narrow our focus and increase our
sensitivity for finding subtle abnormalities that may be clinically
significant.
Don’t hesitate to do a little digging and to bend the ear of our
clinical neurological colleagues. Like Dr. Sacks, they often have a
keen perception and know what they are expecting to see before
the study is performed.
References
Sacks, O. (1985). The man who mistook his wife for a hat and other clinical tales. New York:
Summit Books.
Sacks, O. (2012). Hallucinations. New York: Random House.
Sacks, O. (1982). The leg. London Review of Books, 11(4), 3-5.
Afifi, A. K., & Bergman, R. A. (1998). Functional neuroanatomy: Text and atlas. New York:
McGraw-Hill, Health Professions Division.
Di Pietro, M., Laganaro, M., Leemann, B., Schnider, A. “Receptive amusia: temporal auditory
processing deficit in a professional musician following a left temporo-parietal lesion”
Neuropsychologi 42 (2004): 868-877 April 2016.