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1. CORPUS CALLOSUM & ITS
ABNORMALITIES
( FINAL REVIEW PROJECT )
AFFAF KHAN

2. LAYOUT
▪ CORPUS CALLSOUM :-
* INTRODUCTION
* LOCATION
* PARTS
* FORMATION
* FUNCTIONS
▪ ABNORMALITIES OF CORPUS CALLOSUM :
* AGENESIS
▪ CASE STUDY :
* COMPLETE AGENESIS
* PARTIAL AGENESIS
▪ ANALYSIS OF THE COURSE

3. CORPUS CALLOSUM
" a great interhemispheric commisure consisting of large white
matter tracts that connects the two halves of cerebrum "
▪ It is C shaped .
▪ It is formed in the brain 12 to 16 weeks after conception , and
continues to develop throughout the childhood .
▪ By the age of 12 years , its development is completed .

4. LOCATION OF CORPUS CALLOSUM
▪ Directionally, the corpus callosum is located underneath the
cerebrum at the midline of the brain. It resides within
the interhemispheric fissure, which is a deep furrow that separates
the brain hemispheres.
▪ The corpus callosum is near the center of the brain and is covered by
the cerebral hemispheres.
▪ It lies deep to the cingulate gyrus , superficial to the fornix , to which
it is connected anteriorly by the septum pellucidum.

5. PARTS OF CORPUS CALLOSUM

6. Detail
▪ The rostrum is continuous with the lamina terminalis and connects
the orbital surfaces of the frontal lobes.
▪ The genu is the bend of the anterior corpus callosum and the forceps
minor is a tract that projects fibres from the genu to connect the
medial and lateral surfaces of the frontal lobes.
▪ The body forms the long central section and its fibres pass through
the corona radiata to reach the surface of the hemispheres.
▪ The splenium tapers awayat the posterior section, with the forceps
major projecting fibres from the splenium to connect the two
occipital lobes.
▪ A narrowed part between the trunk and the splenium is known as
the isthmus.

7. FORMATION OF CORPUS CALLOSUM
▪ There are approximately 200 million axons that form the corpus
callosum.
▪ At 12 to 13 weeks of gestation, nerve fibers begin to cross the
midline, giving rise to connections that later become the corpus
callosum. By 18 weeks, all components of the corpus callosum can be
visualized using a transvaginal sonogram,completed by age of 12.
▪ It begins with the genu and then continues posteriorly along the
body to the splenium.The rostrumis the last part to be formed.

8. RELATIONS OF CORPUS CALLOSUM
▪ On either side of the corpus callosum, the transverse fibers of corpus
callosum radiate in the white matter and pass to the various parts of
the cerebral cortex ;
▪ Those curving forward from the genu into the frontal
lobes constitute the forceps minor (also forceps anterior)
▪ Those curving backward from the splenium into the occipital lobes,
the forceps major (also forceps posterior).
▪ Between these two parts is the main body of the fibers which
constitute the tapetum and extend laterally on either side into
the temporal lobe .The tapetum and anterior commissure share the
function of connecting left and right temporal lobes.

10. NEURONAL FIBERS OF CORPUS CALLOSUM
▪ Thinner, lightly myelinated fibers are slower conducting and they
connect the association and prefrontal areas.
▪ Thicker and fast-conducting fibers connect the visual and motor
areas.
▪ The tractogram pictured, shows the nerve tracts from six segments
of the corpus callosum, providing linking of the cortical regions
between the cerebral hemispheres.
▪ Those of the genu are shown in coral, of the premotor – green, of the
sensory-motor – purple, of the parietal – pink, of the temporal –
yellow, and of the splenium – blue.

11. • Thinner axons in the genu connect the prefrontal
cortex between the two halves of the brain; these fibers arise
from a fork-like bundle of fibers from the tapetum, the forceps
minor.
• Thicker axons in the trunk of the corpus callosum, interconnect
areas of the motor cortex, with proportionately more of the
corpus callosum dedicated to supplementary motor regions
including Broca's area.
• The splenium, communicates somatosensory information
between the two halves of the parietal lobe and the visual
cortex at the occipital lobe, these are the fibers of the forceps
major

12. FUNCTIONS OF CORPUS CALLOSUM
▪ The main function of the corpus callosum is the communication
between the two hemispheres ; transferring cognitive, sensory, and
motor information between them.
▪ The rostrum and genu connect the frontal lobes of the left and the
right hemisphere .
▪ The body and the splenium connect the temporal lobes of the
hemispheres as well as the occipital lobes.

13. • Involved in the transfer of visual, auditory, and somatosensory
information in posterior regions, and higher cognition is processing
anteriorly .
• There is evidence for the idea that the anterior callosal fibers transfer
motor information between the frontal lobes, and the posterior fibers
are involved in the processing of somatosensory (posterior midbody),
auditory (isthmus) and visual (splenium) cues by connecting the
parietal, temporal, and occipital lobes .
• As the brain matures and white matter develops, the corpus callosum
seems to play a crucial role in refining motor movements and
cognitive functions .
• Additional studies have shown that the corpus callosum has an
inhibitory effect that normally prevents alien-hand syndrome and
uncoordinated hand-motor behavior .

15. BLOOD SUPPLY OF CORPUS CALLOSUM
▪ The internal carotid artery network provides arterial blood supply to
a majority of the corpus callosum, specifically via the pericallosal
artery (a branch of the anterior cerebral artery).
▪ The splenium is the exception as it receives vascular input from the
vertebrobasilar system.
▪ The terminal and choroidal branches of the posterior cerebral
artery supply the splenium with arterial blood.
▪ Venous drainage occurs via the callosal and callosal cingular veins
and finally , the internal cerebral veins.

16. OBSERVATION OF CORPUS CALLOSUM
Corpus callosum has been studied over the years through the use
of :
MRI , Ultrasound
Brains of deceased human individuals
Animals such as cats , monkeys ,rats

17. ABNORMALITIES OF CORPUS CALLOSUM
1. AGENESIS OF CORPUS CALLOSUM :
Complete agenesis :This is when the corpus
callosum does not form at all.The front, middle, and back parts are all
missing.
Partial agenesis : This is when part of the corpus
callosum is missing, usually just the back part. Sometimes it is the middle or
front part that is missing instead.
ADDITIONAL TYPES :-
2. HYPOPLASIA OF CORPUS CALLOSUM : This is when all parts of the
corpus callosum form, but the entire structure is very thin or very small.
3. CORPUS CALLOSUM ABNORMALITY DUE TO HYDROCEPHALUS :This
is when too much fluid in the brain causes the corpus callosum to not form
properly.

18. AGENESIS OF CORPUS CALLOSUM
" a rare disorder characterized by a partial or complete absence
(agenesis) of an area of the brain that connects the two cerebral
hemispheres "
▪ It is present at birth ( congential )
▪ can be inherited as either an autosomal recessive trait or an X-
linked dominant trait.
▪ heterogeneous condition ranging from severe intellectual disability
to normal cognitive function

19. CAUSES OF AGENESIS
▪ Disruption of brain cell migration during fetal development.
▪ Chromosomaldefects that affect fetal brain development
▪ Certain viral infections that a mother has while pregnant such
as rubella
▪ Abnormal brain development caused by cystsprenatal infections
▪ Tenetic abnormalities, such as Andermann or Aicardi syndromes
▪ Toxic metabolic conditions, such as fetal alcohol syndrome (heavy
drinking or alcoholism during pregnancy)
▪ Injury during the twelfth to the twenty-second week of pregnancy
(intrauterine) leading to developmental disturbance of the fetal
brain

20. OCCURRENCE OF AGENESIS
▪ between the 3rd and 12th week of gestational life
▪ Though rare,it is one of the more frequently occurring congenital
malformations, affecting three to seven people per 1000 births.
▪ Injuryduring surgery or accident during later years of life leading
to partial agenesis
▪ In persons with developmental disabilities: 2.2%‐ 2.4%
▪ In persons with FetalAlcohol Syndrome: 6.8%
▪ In the normalpopulation: 0.0005% ‐ 0.7%
▪ Incidence is increased in patients with Trisomy 18 andTrisomy 13

21. SIGNS & SYMPTOMS OF AGENESIS
▪ Neurological (brain and nerve) problems
▪ Seizures or Epilepsy ( within first 2 years )
▪ Trouble with tasks that require two hands
▪ Trouble with balance or depth perception (judging depth and
distance correctly)
▪ Behavioral and learning problems
▪ Challenges with self-control, making decisions, or problem solving
▪ Speech delays or language challenges
▪ Learning or intellectual disabilities
▪ Behavioral or mental health challenges

22. DIAGNOSIS OF AGENESIS
▪ Diagnosis is made by viewing the brain through
▪ MRI,
▪ CT scan
▪ Prenatal or post-natal ultrasound
Partial
agenesis
Complete
Agenesis

23. ADDITIONAL ABNORMALITIES CAUSED BY
AGENESIS
These include:
▪ fluid in the skull, known as hydrocephalus
▪ Arnold-Chiarimalformations
▪ failure of the forebrainto divide into lobes
▪ disordersof neural migration
SYNDROMES associatedwith agenesisinclude:
▪ Aicardi
▪ Andermann
▪ Acrocallosal
▪ Menkes
▪ Agenesisof the corpus callosumcan also happenin conjunctionwith spinabifida.

24. TREATMENT OF AGENESIS
▪ There is no standard course of treatment for ACC.
▪ Treatment usually involves management of symptoms and seizures if they
occurAnti-seizure medications.
▪ Early Intervention (EI) services to monitor for and treat developmental
delays
▪ Physical therapy to treat movement difficulties
▪ Occupational therapy to help build everyday skills
▪ Speech therapy to help with speech and language development
▪ Special education in your child’s school
▪ When hydrocephalus is present it may be treated with a surgical shunt to
drain the fluid from the brain cavity .
▪ Genetic counseling

25. CASE STUDY OF COMPLETE
AGENESIS
▪ A baby girl was born five (5) weeks prematurevia
C‐section because of nerve loss and blood clot in
mother & was kept in ICU overnight .At age of two
(2) months, contracted Respiratory SyncytialVirus
(RSV) with suspected seizure activity occurred ,
accompanied with slow oral‐motor stimulation,
feeding and movement.The baby was then
referred to a neurologist .

26. SIGNS & SYMPTOMS OBSERVED BY
NEUROLOGIST
▪ Cognitive skills within normal limits
▪ At age 18 months, testing revealed receptive
language skills had mild expressive delay .
Exhibited single word vocabulary (mostly nouns)
with beginning two word combinations
▪ Used gestures to assist in communication
▪ Imaginative play, turn‐taking , choice making,
answered questions, identified objects , followed
simple directions , speech better understood when
text was known .

27. CAUSES OF SIGNS & SYMPTOMS
▪ Respiratory SyncytialVirus (RVS) resulted in loss of
entire corpus callosum .
▪ As it occurred at a very young age , both the
cerbral hemispheres were able to co-ordinate with
each other rather than resulting in a split-brain
situation .
▪ Hence, cognitive skills are within normal limits .
▪ Language skills had mild expressive delay
because sensory signals are unable to pass through
corpus callosum to reach the speech areas in left
hemisphere .

28. DIAGNOSIS & TREATMENT
▪ The condition of the child was diagnosed to be " COMPLETE
AGENESIS " of corpus callosum
▪ Treatment :-
* Medications to control seizures.
* Speech therapy to help with speech and language
development.
* Physical therapy to improve muscle strength and
coordination.
* Section of corpus callosum has been attempted surgically
inorder to prevent spread of seizures from one hemisphere to another.

29. CASE STUDY OF PARTIAL
AGENESIS
▪ A baby boy was born weighing 7 lbs . Failure to
thrive was observed at 4th month and was given
services from public health nurse until 12 months
of age . Parents noticed delay in rolling over (6
months) , sitting (9 months) , crawling (12
months), walking independently ( 21 months ).
delay in frequencyof vocalization and babbling (12
months) was also observed .The parents were
then refered to a neurologist by a pediatrician by
the age of 3 .

30. SIGNS & SYMPTOMS OBSERVED BY
THE NEUROLOGIST
▪ Severe/profound delays in communication, motor,
cognitive, social‐emotional and adaptive domains
▪ Limited engagement with peers and activities
▪ Use of gestures and vocalizations to obtain
attention of teachers/clinicians
▪ Verbalizations repeated severaltimes before
attempted responses were made

31. CAUSES OF SIGNS & SYMPTOMS
▪ Profund delay in communication , motor , cognitive , social-
emotional & adaptive domain is due to delay/ less amount of sensory
signals reaching the right hemisphere , especially the comprehensive
& production areas analogous to Wernicke's & Broca's area to the
left & lack of fibres reaching frontal cortex which is also responsible
for communication difficulties and behavioural abnormalities .
▪ Limited attraction with peers & activities is due to inability to
understand the tone & emotional state of person speaking , enen
though meaning of words are understood .
▪ Use of gestures & vocalization was due to less amount of signals
reaching the Broca's area , causing difficulty in using of words & lack
of primary motor cortex to generate neuronalimpulses that control
the execution of movement.
▪ Verbalization is repeated several types because ability to
comprehend which is done through Broca's area is reduced .

32. DIAGNOSIS & TREATMENT
▪ The condition of the child was diagnosed to
be " PARTIAL AGENESIS " of corpus callosum .
▪ Treatment :-
* Medications to control seizures.
* Speech therapy to help with speech and
language development.
* Physical therapy to improve
muscle strength and coordination.
* Occupational therapy to help build self-
care and mobility skills such as eating, getting dressed,
and walking

33. ANALYSIS OF THE COURSE
▪ It has really helped me understand how difficult it is for people with
disabilities to survive , how they cope up with it and continue to
fight with their specific conditions in hopes of living a normal life .
▪ It has changed my perspective towards them .
▪ It has also helped me in observing the signs & symptoms of various
diseases in my surroundings and help those people out by asking
them to visit a doctor .
▪ It has also helped me observe how people suffering from a particular
disability have adapted to their new lives and given me a better
understanding of how the human brain works to assist normal body
functions during various disease conditions.
▪ It has shown me how much the scientific , biological field has
expanded and how people are able to functional normally even after
complex surgeries

34. • It has helped me observe how many older people suffer from hearing
problems and how the modern day technology has made hearing
easier for them .

35. THANK YOU