Speech disorders

Speech
Anatomy & Physiology of Speech
Disorders of Speech
By Dr.Vitrag Shah

Dr.Vitrag Shah - www.medicalgeek.com

Communication Process

 Communication symbols

 Communication signals


Dominant Vs Non-Dominant Hemisphere
 The concept of "cerebral dominance" and a
dominant and nondominant hemisphere
has been replaced by a concept of
complementary specialization of the
hemispheres, one for sequential-analytic
processes (the categorical hemisphere) and
one for visuospatial relations (the
representational hemisphere).
 The categorical hemisphere is concerned
with language functions.


Speech & Hemispherical Dominance
 Hemispheric specialization is related to handedness.
 Handedness appears to be genetically determined. In 96% of
right-handed individuals, who constitute 91% of the human
population, the left hemisphere is the dominant or categorical
hemisphere, and in the remaining 4%, the right hemisphere is
dominant. In approximately 15% of left-handed individuals, the
right hemisphere is the categorical hemisphere and in 15%, there
is no clear lateralization. However, in the remaining 70% of left-
handers, the left hemisphere is the categorical hemisphere.
 It is interesting that learning disabilities such as dyslexia , an
impaired ability to learn to read, are 12 times as common in left-
handers as they are in right-handers, possibly because some
fundamental abnormality in the left hemisphere led to a switch
in handedness early in development.
 However, the spatial talents of left-handers may be well above
average; a disproportionately large number of artists, musicians,
and mathematicians are left-handed. For unknown reasons, left-
handers have slightly but significantly shorter life spans than
right-handers.


 It is interesting that in individuals who learn a
second language in adulthood, fMRI reveals that the
portion of Broca's area concerned with it is adjacent
to but separate from the area concerned with the
native language.
 However, in children who learn two languages early
in life, only a single area is involved with both. It is
well known, of course, that children acquire fluency
in a second language more easily than adults.
 The speech area of the adult cortex is larger on the
left than on the right. It is believed that the two
hemispheres of the newborn have equipotential
capabilities. During childhood, one hemisphere
slowly comes to dominate the other, and it is only
after the first decade that the dominance becomes
fixed. This would explain why a 5-year-old child with
damage to the dominant hemisphere can easily
learn to become left-handed and speak well,
whereas in the adult this is almost impossible.

NEUROANATOMY
 The cerebral cortex of the human brain contains
approximately 20 billion neurons spread over an
area of 2.5 m2.
 Five anatomically defined large-scale networks are
most relevant to clinical practice: (1) a perisylvian
network for language, (2) a parietofrontal network
for spatial cognition, (3) an occipitotemporal
network for face and object recognition, (4) a limbic
network for retentive memory, and (5) a prefrontal
network for cognitive and behavioral control.

 The primary brain areas concerned with language
are arrayed along and near the sylvian fissure
(lateral cerebral sulcus) of the categorical
hemisphere.

Broca’s Area or Brodmann areas 44 & 45
 The motor speech area of Broca is located in the
posterior inferior frontal gyrus (between the
anterior and ascending rami and the ascending and
posterior rami of the lateral fissure)(Brodmann areas
44 and 45).
 The Broca speech area brings about the formation of
words by its connections with the adjacent primary
motor areas; the muscles of the larynx, mouth,
tongue, soft palate, and the respiratory muscles are
appropriately stimulated & controls the output of
spoken language.
 The sequencing function of Broca's area also
appears to involve the ordering of words into
sentences that contain a meaning-appropriate
syntax (grammar).

Wernicke's area or Brodmann's area 22
 The sensory speech area of Wernicke is localized in
the left dominant hemisphere, mainly in the
superior temporal gyrus, with extensions around
the posterior end of the lateral sulcus into the
parietal region.
 The Wernicke area is connected to the Broca area
by a bundle of nerve fibers called the arcuate
fasciculus.
 It receives fibers from the visual cortex in the
occipital lobe and the auditory cortex in the
superior temporal gyrus.
 The Wernicke area permits the understanding of
the written and spoken language and enables a
person to read a sentence, understand it, and say it
out loud

Angular gyrus
 The angular gyrus in the inferior parietal
lobule is adjacent to visual receptive areas
and subserves the perception of written
language, as well as other language
processing functions.
 Destructive lesions in the angular gyrus in
the posterior parietal lobe (often considered
a part of the Wernicke area) divide the
pathway between the visual association area
and the anterior part of the Wernicke area.
This results in the patient being unable to
read (alexia) or write (agraphia).

Insula
 The insula is an area of the cortex that is
buried within the lateral sulcus and forms its
floor.It can be examined only when the lips
of the lateral sulcus are separated widely.
 It is believed that this area is important for
planning or coordinating the articulatory
movements necessary for speech.
 Patients who have lesions involving the
insula have difficulty in pronouncing
phonemes in their proper order and usually
produce sounds that are close to the target
word but are not exactly correct.

Physiology of Speech & Language
 A region at the posterior end of the superior temporal gyrus
called Wernicke's area is concerned with comprehension of
auditory and visual information. It projects via the arcuate
fasciculus to Broca's area (area 44) in the frontal lobe
immediately in front of the inferior end of the motor cortex.
 Broca's area processes the information received from
Wernicke's area into a detailed and coordinated pattern for
vocalization and then projects the pattern via a speech
articulation area in the insula to the motor cortex, which
initiates the appropriate movements of the lips, tongue, and
larynx to produce speech.
 The probable sequence of events that occurs when a subject
names a visual object is shown in Figure 19–8. The angular
gyrus behind Wernicke's area appears to process information
from words that are read in such a way that they can be
converted into the auditory forms of the words in Wernicke's
area.


Word deafness:
 Difficulty in understanding the meaning of words heard.
Word blindness:
 Difficulty in understanding the meaning of words seen.
Bradylalia:
 Slowness of speech e.g. in Hypothyroidism, Depression,
Parkinsonism
Echolalia:
 Repetition of examiner’s words by patient.
Palilalia:
 Repetition of terminal words of own speech.
Paraphasia:
 Simple syllabic words are missing and replaced by
substitutions so that desired response is only
approximated.
 Literal : Incorrect letters (Grass is green)
 Verbal : Incorrect words (Grass is blue)
 Neologisms: Nonsense words (Grass is grumps)

Prerequisites before testing speech
 Level of consciousness
 Handedness
 Mother language
 Intelligence level
 Deaf of not
 Vision

 Mutism is inability to speak while
Aphonia is inability to produce sounds.


Aphasia


Algorithm for approach to Aphasia

APHASIA

Fluent
Nonfluent

Poor Repetition Good Repetition

Poor Repetition Good Repetition

PC GC PC GC
Wernicke Conduction TC Sensory Anomic
PC GC PC GC
Global Broca Mixed TC TC motor

TC – Transcortical
PC – Poor comprehension
GC – Good comprehension

 When asked to name a common object (pencil or
wristwatch), the patient may fail to come up with
the appropriate word, may provide a
circumlocutious description of the object ("the
thing for writing"), or may come up with the wrong
word (paraphasia).

 If the patient offers an incorrect but related word
("pen" for "pencil"), the naming error is known as
a semantic paraphasia; if the word approximates
the correct answer but is phonetically inaccurate
("plentil" for "pencil"), it is known as a phonemic
paraphasia.


Ony-way vs Two-way naming deficit

 In most anomias, the patient cannot retrieve
the appropriate name when shown an
object but can point to the appropriate
object when the name is provided by the
examiner. This is known as a one-way (or
retrieval-based) naming deficit. A two-way
naming deficit exists if the patient can
neither provide nor recognize the correct
name, indicating the likely presence of a
comprehension impairment for the word.

 Broca's aphasia is not just an "expressive" or "motor" disorder and
that it also may involve a comprehension deficit for function words
and syntax.
 Patients with Broca's aphasia can be tearful, easily frustrated, and
profoundly depressed. Insight into their condition is preserved, in
contrast to Wernicke's aphasia.
 Even when spontaneous speech is severely dysarthric, the patient
may be able to display a relatively normal articulation of words
when singing. This dissociation has been used to develop specific
therapeutic approaches (melodic intonation therapy) for Broca's
aphasia.
 Additional neurologic deficits usually include right facial weakness,
hemiparesis or hemiplegia, and a buccofacial apraxia
characterized by an inability to carry out motor commands
involving oropharyngeal and facial musculature (e.g., patients are
unable to demonstrate how to blow out a match or suck through a
straw). Visual fields are intact.
 The cause is most often infarction of Broca's area and surrounding
anterior perisylvian and insular cortex due to occlusion of the
superior division of the middle cerebral artery
 When the cause of Broca's aphasia is stroke, recovery of language
function generally peaks within 2 to 6 months, after which time
further progress is limited.

(Jargon Aphasia)


 The patient does not seem to realize that his or her
language is incomprehensible and may appear angry and
impatient when the examiner fails to decipher the
meaning of a severely paraphasic statement. In some
patients this type of aphasia can be associated with severe
agitation and paranoid behaviors.
 One area of comprehension that may be preserved is the
ability to follow commands aimed at axial musculature.
The dissociation between the failure to understand simple
questions ("What is your name?") in a patient who rapidly
closes his or her eyes, sits up, or rolls over when asked to
do so is characteristic of Wernicke's aphasia and helps
differentiate it from deafness, psychiatric disease, or
malingering.
 An embolus to the inferior division of the middle cerebral
artery, to the posterior temporal or angular branches in
particular, is the most common etiology .
 Some patients with Wernicke's aphasia due to
intracerebral hemorrhage or head trauma may improve as
the hemorrhage or the injury heals. In most other patients,
prognosis for recovery of language function is guarded.

 Reading aloud is impaired, but reading
comprehension is preserved.

 The lesion sites spare Broca's and
Wernicke's areas but may induce a
functional disconnection between the
two so that neural word representations
formed in Wernicke's area and adjacent
regions cannot be conveyed to Broca's
area for assembly into corresponding
articulatory patterns.


Anomic aphasia is the single most common language disturbance seen in head trauma,
metabolic encephalopathy, and Alzheimer's disease.

The lesion site disconnects the intact language network from prefrontal areas of the brain and
usually involves the anterior watershed zone between anterior and middle cerebral artery
territories or the supplementary motor cortex in the territory Dr.Vitrag Shah - www.medicalgeek.com
of the anterior cerebral artery.

Isolation Aphasia
 This rare syndrome represents a combination of the two
transcortical aphasias. Comprehension is severely
impaired, and there is no purposeful speech output.

 The patient may parrot fragments of heard conversations
(echolalia), indicating that the neural mechanisms for
repetition are at least partially intact.

 This condition represents the pathologic function of the
language network when it is isolated from other regions of
the brain. Broca's and Wernicke's areas tend to be spared,
but there is damage to the surrounding frontal, parietal,
and temporal cortex.

 Lesions are patchy and can be associated with anoxia,
carbon monoxide poisoning, or complete watershed zone
infarctions. Dr.Vitrag Shah - www.medicalgeek.com

Pure Word Deafness
 The most common causes are either bilateral or
left-sided middle cerebral artery (MCA) strokes
affecting the superior temporal gyrus.
 The net effect of the underlying lesion is to
interrupt the flow of information from the
auditory association cortex to Wernicke's area.
 Since auditory information cannot be conveyed to
the language network, however, it cannot be
decoded into neural word representations, and
the patient reacts to speech as if it were in an
alien tongue that cannot be deciphered.
 Patients cannot repeat spoken language but have
no difficulty naming objects. In time, patients
with pure word deafness teach themselves
lipreading and may appear to have improved.


Pure Alexia Without Agraphia
 This is the visual equivalent of pure word
deafness. The lesions interrupt the flow of
visual input into the language network.
There is usually a right hemianopia, but the
core language network remains unaffected.
 Patients with this syndrome also may lose
the ability to name colors, although they can
match colors. This is known as a color
anomia.
 The most common etiology of pure alexia is
a vascular lesion in the territory of the
posterior cerebral artery or an infiltrating
neoplasm in the left occipital cortex

Aphemia (Pure word mutism)
 There is an acute onset of severely
impaired fluency (often mutism), which
cannot be accounted for by corticobulbar,
cerebellar, or extrapyramidal dysfunction.
Recovery is the rule and involves an
intermediate stage of hoarse whispering.
 Writing, reading, and comprehension are
intact, and so this is not a true aphasic
syndrome.


Aprosodia

 Variations of melodic stress and intonation
influence the meaning and impact of spoken
language. For example, the two statements "He is
clever." and "He is clever?" contain an identical
word choice and syntax but convey vastly
different messages because of differences in the
intonation and stress with which the statements
are uttered. This aspect of language is known as
prosody.
 Damage to perisylvian areas in the right
hemisphere can interfere with speech prosody
and can lead to syndromes of aprosodia.


Subcortical Aphasia
 Damage to subcortical components of the
language network (e.g., the striatum and
thalamus of the left hemisphere) also can
lead to aphasia.
 In a patient with a CVA, an anomic
aphasia accompanied by dysarthria or a
fluent aphasia with hemiparesis should
raise the suspicion of a subcortical lesion
site.


Progressive Aphasias
 Aphasias caused by cerebrovascular accidents start suddenly
and display maximal deficits at the onset.These are the "classic"
aphasias described above.
 Aphasias caused by neurodegenerative diseases have an
insidious onset and a relentless progression so that the
symptomatology changes over time.
 The single most common sign of primary progressive aphasia is
an inability to come up with the right word during conversation
and/or an inability to name objects shown by the examiner
(anomia).
 The impairments of syntax, comprehension, naming, or writing
in PPA form slightly different patterns from those seen in CVA-
caused aphasias.
 Three subtypes of PPA can be recognized: an agrammatic
variant characterized by poor fluency and impaired grammar, a
semantic variant characterized by preserved fluency and syntax
but poor single word comprehension, and a logopenic variant
characterized by preserved syntax and comprehension but
frequent word-finding pauses during spontaneous speech.


Wernicke-Lichtheim Model


Case : Aphasia
 A 49-year-old man with hypertrophic cardiomyopathy
has three episodes of difficulty speaking over the
course of a day. The episodes are brief, each lasting
less than 30 seconds. He is fully aware of the events.
He is able to understand what is being said to him at
the time. The following day he loses consciousness
and is taken to the local hospital, where he is found
to have an irregular cardiac rhythm. He attempts to
speak but is unable to produce any words or sounds.
He is able to follow both written and verbal
commands. Brain MRI reveals an acute infarct in the
left inferior frontal lobe. The patient is diagnosed
with Broca’s aphasia secondary to a stroke caused by
a cardiac embolism. Over the course of several
weeks, he gradually regains the ability to speak;
however, his fluency and ability to repeat phrases
spoken to him remain impaired.

Gerstmann's Syndrome
 The combination of acalculia (impairment of
simple arithmetic), dysgraphia (impaired writing),
finger anomia (an inability to name individual
fingers such as the index and thumb), and right-
left confusion .
 In making this diagnosis it is important to
establish that the finger and left-right naming
deficits are not part of a more generalized anomia
and that the patient is not otherwise aphasic.
 When Gerstmann's syndrome is seen in isolation,
it is commonly associated with damage to the
inferior parietal lobule (especially the angular
gyrus) in the left hemisphere.

Dysarthria
Cerebellar Dysarthria:
 Patient speaks slowly and deliberately, syllable by syllable as if
scanning a line of poetry and the normal prosodic rhythm is lost
(Scanning speech).
 When the speech has explosive character & slurring of consonants,
it’s called Staccato speech.
Cortical Dysarthria:
 Irregular hesitancy in word production associated with difficulty in
abstract, volitional movements of the lips and tongue (Orofacial
apraxia). Usually associated with aphasia.
Rigid Dysarthria:
 Due to extra-pyramidal involvement – low volume, monotonous
speech of parkinsonism.
Pseudobulbar (Spastic) Dysarthria:
 Individual syllables are slurred and the precision of consonant
pronounciation is lost.Due to leisons in corticospinal fibres supplying
muscles of face, larynx, tongue & respiration. Difficulty in
pronouncing b, p, t.
Bulbar (Flaccid) dysarthria:
 LMN palsy affects the muscles of articulation. Non specific slurring of
speech present.

Bibilography
 Harrison’s principles of internal medicine
18th Edition
 Bedsideclinics in medicine by Dr.Arup
kumar kundu
 Manual of Practical Medicine – B
Alagappan
 Bickerstaff's Neurological Examination in
Clinical Practice
 Slides by Dr.Aswini Kumar

Thanks


Speech disorders

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (18)

Similar to Speech disorders

Similar to Speech disorders (20)

More from Vitrag Shah

More from Vitrag Shah (18)

Recently uploaded

Recently uploaded (20)

Speech disorders