Dysphasia is a disorder of the content of speech and usually follows a lesion of the dominant cortex:
· When the speech dejectis expressive dysphasia or nominal dysphasia or motor dysphasia, the site of the lesion in the cortex is the posterior inferior part of the dominant frontal lobe, i.e. Broca's area.
· When the speech defect is sensory dysphasia or receptive dysphasia, the site of the lesion is the superior temporal lobe or Wernicke's area.
What do you understand by the term 'dysarthria'?
Dysarthria is an inability to articulate properly because of local lesions in the mouth or disorders of speech muscles or their connections. There is no disorder of the content of speech. The causes of dysarthria are:
· Stutter.
· Paralysis of cranial nerves - Bell's palsy, ninth, tenth and eleventh nerves.
· Cerebellar disease - staccato, scanning speech.
· Parkinson's speech - slow, quiet, slurred, monotonous.
· Pseudobulbar palsy - monotonous, high-pitched 'hot potato' speech.
· Progressive bulbar palsy - nasal.
What are the components of speech?
· Phonation: abnormality is called dysphonia.
· Articulation: abnormality is called dysarthria.
· Language: abnormality is called dysphasia.
What are the other dominant hemisphere functions?
· Right-left orientation.
· Finger identification.
· Calculation.
What are the non-dominant hemisphere functions?
· Drawing ability.
· Topographic ability.
· Construction.
· Dressing.
· Facial recognition.
· Awareness of body and space.
· Motor persistence.
What are the parietal lobe signs?
· Loss of accurate localization of touch, position, joint sense and temperature appreciation.
· Loss of two-point discrimination.
· Astereognosis.
· Dysgraphaesthesia.
· Sensory inattention.
· Attention hemianopia, homonymous hemianopia, or lower quadrantic hemianopia.
What do you understand by the term 'agnosia'?
Agnosia is a failure to recognize objects despite the fact that the sensory pathways for sight, sound or touch are intact. This is tested by asking the patient to feel, name and describe the use of certain objects.
What are the different types of agnosia?
Different types of agnosia include:
· Tactile agnosia and astereognosis: where the patient is unable to recognize objects placed in his hands despite the fact that the sensory system of the hands and fingers is intact and there is adequate motor function to allow him to examine the object. The lesion is in the parietal lobe.
· Prosopagnosia: inability to recognize a familiar face. The lesion is in the parieto-occipital lobe.
· Visual agnosia: inability to recognize objects despite the fact that the main visual pathways to the occipital cortex are preserved. The lesion is in the parieto-occipital lobe.
· Anosognosia: the lack of awareness or realization that the limbs are paralysed, weak or have impaired sensation. The lesion is usually in the non-dominant parietal lobe.
What do you understand by the term 'apraxia'?
Apraxia is the inability to perform purposeful volitional movements in the absence of motor weakness, sensory deficits or severe incoordination. Usually the defect is in the dominant parietal lobe, with disruption of connections to the motor cortex and to the
opposite hemisphere.
What are the different types of apraxia?
Different types ot apraxta include:
· Dressing apraxias: the patient is unable to put on his clothes correctly.
· Gait apraxia: difficulty in walking, although patients may show intact leg move-ments when examined in bed.
· Ideomotor apraxia: patients are unable to perform movements on command. although they may do this automatically, e.g. lick
their lips.
· Ideational apraxias: difficulty in carrying out a complex series of movements, e.g. to take a match from a box to light a cigarette.
· Constructional apraxia: the patient has difficulty in arranging patterns of blocks or copying designs.
What do you know about dyslexia?
Reading difficulties, including dyslexia, occur as a part of a continuum that also includes normal reading ability. It is not an all-or-none phenomenon but, like hyper-tension, occurs in degrees. It has been defined as a disorder that is manifested by difficulty in learning to read despite conventional instruction, adequate intelligence and sociocultural opportunity.
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