Transcript Sensory Disorders - Kelley Kline Phd

Sensory and Neurological Disorders
Dr. Kline
FSU-PC
I. Sensory Disorders

Are comprised of deficits in sensory
modalities resulting from neurological
damage to the CNS.
A. Visual disorders


1. Scotomas- small blind spots in the visual field
resulting from damage to the primary visual cortex .
**May also occur temporarily during migraines.

Most people are unaware of these because of
nystagmus, constant tiny involuntary eye movements
that “fills in the missing information.”

Blind spots become obvious, if eyes are held still.
2. Cortical blindness

Patients with complete damage to the primary visual
cortex (V1) report being totally blind.

Despite reporting being blind, these patients can grab a
a moving object or track a moving light. Patients
report being unaware of their ability to do this.

The ability of cortically blind people to perform
visually mediated tasks without conscious awareness is
called blindsight.
Cortical Blindness case study: D.B.

D.B, was blind in his left visual field (LVF) because his
right occipital lobe had been surgically removed. He
could see images in his right visual field (RVF) because
his left occipital lobe was intact.

“Even though the patient had no awareness of “seeing” in his
blind field, evidence was obtained that he could reach for visual
stimuli in his left field with considerable accuracy, could
differentiate the orientation of a vertical line from a horizontal
or diagonal line, and could differentiate the letters X and O.”

D.B. showed great surprise at being told he was accurate
at these tasks.
3. Visual Agnosias:

Refers to inability to recognize objects, their
pictorial representations, or to draw or to copy
them.

These people are not blind, they can point to
objects & describe their features. However,
they can’t determine what the object is.
Example of patient with visual agnosia

The patient was shown a key. He could describe the
individual components of the key, but could not say
what the item was.

When shown a stethoscope, he said “a stethoscope is a
long tube with a round thing at the end.”

When told it was a stethoscope he would agree with the
doctor, but could not recognize the object himself.
When told it might not be a stethoscope his response
was that if the doctor didn’t think it a stethoscope he
would not either because he lacked any confidence in
his ability to recognize and name the object.
Types of visual agnosias

a. Visual Object Agnosia: the patient can see the
object, but is unable to name it, demonstrate its use, or
remember having seen it before.

E.g., One patient described a bicycle as “a pole with two
wheels, one in front and one in back.”

Lesion is supposed to be in left occipital lobe in
secondary cortex, although it is most common for the
damage to be bilateral.
b. Visual Agnosia for drawings:

Effects recognition of a variety of drawn stimuli,
including realistic representations of simple
objects, geometric figures, meaningless forms,
incomplete figures, & abstract drawings.

The lesion producing this condition is in
secondary visual cortex.
c. Prosopagnosia

First noticed in 1947 when three patients with head
trauma described the inability to recognize faces
although they were able to recognize objects, forms, &
colors.

People with prosopagnosia cannot identify faces (&
some complex objects). They often recognize others by
their voice or gait.

Damage in prosopagnoisa occurs in two types of cases:
**bilateral damage to the inferior temporal lobe**
**unilateral damage to right posterior parietal lobe**


4. Motion Blindness

Patients with this disorder can see objects, but have
trouble determining whether an object is moving or
stationary.

**For these people life is a series of snap shots or
photos. You can think of it as a series of “freeze
frames.”

**The middle temporal lobe (V5) has cells that respond
to movement. This is the area of damage in patients
with motion blindness.
B. Somatoperceptual Disorders

1. Astereognosia: the inability to recognize objects from
touch (even if able to do so previously). Damage is to
postcentral gyrus (primary somatosensory cortex).

2. Blind touch: patients can identify the location of a
visual stimulus even though they deny “seeing” it.
3. Asomatognosia:Is the loss of knowledge or sense of
one’s own body & bodily condition. The person
neglects part of his or her body.
Asomatognosia—lesion in postcentral gyrus.

These may be for one or both sides of the body.
They do appear to be most common for the left
side of the body resulting from right hemispheric
lesions.
Next slide—description of one of Oliver Sacks’
patients with asomatognosia.
The patient had felt fine all day and fallen asleep towards evening.
When he woke up he felt fine until he moved in the bed.

Then he found, as he put it, ‘someone’s leg’ in the bed—a severed
human leg!! Stunned & then disgusted, he thought one of the
nurses was playing a joke on him (put a dismembered body part in
bed with him).
…When he threw it out of bed, he somehow came after it—and
now it was attached to him. “Look at it!” he cried. “Have you
ever seen such a creepy, horrible thing?… The nurse asked him to
remain calm. He became irritated arguing, “Why!” The doctor
then came and answered “Don’t you know your own leg?” The
patient responded, “Ah, Doc!, you’re folling me! You’re in
cahoots with that nurse.” Sacks responded, “Listen, I don’t think
you’re well. Please allow us to return you to bed. But I want to
ask you one final question. If this—this thing—is not your left
leg… then where is your own left leg?” The patient, looked pale
and said, “I don’t know, I have no idea, its disappeared, gone
forever.”
4. Contralateral Neglect

Usually caused by right posterior parietal lobe
damage, this disorder was first described in
1874.
Famous case study highlighted disorder:
 Mr. P, 67 at the time of his right parietal lobe
stroke, had unusual symptoms post-stroke.

Mr. P’s Symptoms:



1. He neglected the left side of his body & world.
E.g., when asked to life the arms up, he would fail to lift
the left arm.
2. He would draw a clock face, with all the numbers
crowded on the right side of the clock.
3. He ignored tactile sensations on the left side of the
body.
e.g., Didn’t brush hair of left side or teeth in left side of
mouth.
Contralateral neglect symptoms

Global deficit--neglect of visual, auditory, & somaesthetic
(somatosensory) stimulation on the side of the body and/or
space opposite to the lesion.

Unilateral spatial neglect (usually left side)
Visual spatial neglect (deficit in comprehending visual space)
Dressing apraxia—dress half of the body
Paralexia-read half of a word
Paragraphia-writes only half of a word
Hemi-inattention—ignore opposite side of body
Hemi-akinesia-poverty of movement of one side of body.
Anosognosia-denial of illness or symptoms







5. Apraxia

Is a loss of skilled movement that is not caused by
weakness; an inability to move; abnormal tone or
posture, intellectual deterioration, poor comprehension
or other disorders of movement such as tremor.


Two types:
1. Ideomotor apraxia– patients are unable to copy
movements or to make gestures (waving hello).

Damage appears to be in left posterior parietal area.
2. Constructional apraxia

Refers to a visuomotor disorder in which
patients are unable to perform activities such as
assembling, building, or drawing.

May result from injury to either parietal lobe;
most often found in the posterior parietal region.

E.g., these patients cannot put together a puzzle.
C. Auditory Perceptual disorders
1.
Deficit in perception of brief temporal sequences of
sounds (need more time between sounds).
---Patients have difficulty with rapid sound sequences.

2. Deficits in perceiving rapid speech (related to #1).

3. Auditory sequencing for verbal information may
be impaired. Damage is usually in the left hemispheric
lesion.

4. Cats with unilateral or bilateral lesions of the
auditory cortex lack the ability to localize sounds.
Audioperceptual disorders (contd.)

5. Auditory agnosias-impaired capacity to
recognize nonverbal sounds (very few cases
reported).

6. Amusia-disruption in recognition of
music (tones, melodies, or rhythms).
II. Neurological Disorders

The normal functioning of the CNS can be
affected by a number of disorders, the most
common of which are headaches, tumors,
vascular problems, infections, epilepsy,
head trauma, demyelinating diseases, and
metabolic & nutritional diseases.
A. Vascular Diseases

Vascular diseases in the brain can produce serious—
even total reduction in the flow of oxygen & glucose,
resulting in critical interference with cellular
metabolism.

Interference lasting longer than 10 min., results in all
cells in that region dying.

These are among the most common causes of death &
chronic disability in the Western world.
1. Stroke (Cerebral vascular accident)

Symptoms accompany severe interruption of blood flow
to the brain.

Stroke produces an infarct (area of dead or dying tissue
resulting from obstruction of blood vessels normally
supplying area).

Nature of deficits depend on area of obstruction, size of
blood vessels (better prognosis for small vessels than
large, relative health of surrounding vessels, etc.
2. Cerebral Ischemia- insufficient supply of
blood to brain, are like mini-strokes.


Decreases in blood flow result of 3 causes:
A. Thrombosis-a plug or clot in a blood vessel that
remains at its point of formation.

B. Embolism -moving (clot, bubble of air, sack of
cells, or fat deposit) from larger vessel into a smaller
vessel.

C. Cerebral arteriosclerosis-thickening & hardening
of arteries.
3. Cerebral Hemorrahage

Massive bleeding in the brain. Onset is abrupt &
may be quickly fatal.
Causes:
 Hypertension
 Congenital defects of cerebral arteries
 Leukemia
 Toxic chemicals

4. Aneurysms

Vascular dilations resulting from localized
defects in the elasticity of the vessel.

Most common symptom is severe headache,
often present for many months to years.
B. Open-Head Injuries:

Puncture or penetration of the skull through projectiles
(gunshots/missile wounds) or other moving objects.

Most people with open-head injuries do not lose
consciousness & produce distinctive symptoms that
may undergo rapid & spontaneous recovery.

Deficits are specialized & often resemble those of
surgical excisions.
C. Closed-Head Injuries

Caused by a blow to the head (car accident,
blunt instrument swung at head).

Damage at site of blow is called a coup.

With severe blow, the brain may shift & hit the
opposite side of the skull producing an
additional bruise (contusion) known as a
countercoup.
Closed-Head Injuries (Contd.)

Finally, the brain may suffer additional damage, from
the shearing of nerve fibers resulting in microscopic
lesions.

Frontal & temporal areas most likely to be damaged in
closed-head injuries.

These injuries are common accompanied by loss of
consciousness (from damage to brainstem fibers),
edema (swelling), and hemorrhaging.

Length of coma often is positively correlated with
severity of damage.