Makindo Medical Notes.com

Related Subjects: |Neurological History taking|Cortical functions|Motor System|Sensory System|Mental state Examination |Speech and Language Exam |Cranial nerves and examination |Assessing Cognition

Speech

• Language is mainly produced by the dominant cortex which is the left side in right-handers and the right side in 50% of left-handers.
• Language difficulties therefore often accompanied by right-sided weakness, sensory loss and hemianopia

Structures involved with language

• Various parts of the left and to a lesser extent right cortex are involved and these are
• Broca's area - inferior frontal lobe below the motor strip
• Wernicke's area - posterior temporal lobe and neighbouring parietal lobe
• Arcuate fasciculus which connects the two
• Sound arrives into Heschl's gyrus (primary auditory cortex) of the superior temporal lobe
• Right brain seems involved with prosody and tone of speech

Language Processing

• Sounds processed in Wernicke's area - posterior temporal lobe and neighbouring parietal lobe and decoded into words. Connected closely to limbic system for emotion and the frontal lobe for semantics (meaning).
• Brocas's area in the frontal lobe and close to premotor and motor cortex for mouth and larynx/pharynx generates speech
• Arcuate fasciculus which connects the two
• Physiology is incompletely understood but enough to do a basic examination

Different types of Dysphasia

• Aphasia - no speech produced when there is damage to a large area of left frontal/temporal/parietal usually an MCA infarction
• Expressive dysphasia - reduced words, hesitant, non-fluent non-grammatical speech. Understands simple verbal commands (do not give visual clues) e.g. touch your nose, touch your right ear with your left hand. Communication by writing also usually affected. Damage to Brocas's area just below the motor strip in the frontal lobe. Associated right hemiparesis.
• Receptive dysphasia - comprehension is affected but can produce some normal speech. Impaired naming. Impaired reading/writing. Damage to Wernicke's area. May have associated with hemianopia.
• Conduction dysphasia - cannot repeat words or phrases. As them to repeat "no ifs ands or buts" Involves arcuate fasciculus between speech areas or a large area of damage
• Commonest causes are stroke (ischaemic and haemorrhage) and space-occupying lesions affecting the grey matter.
• Language deficits such as aphasia may be the predominant feature in some dementias - primary progressive aphasia

Dyslexia and Dysgraphia

• Inability to read and communicate by writing. Usually a dominant parietal lobe deficit
• Usually accompanies a language deficit. Those with dysphasia usually have matching dyslexia and dysgraphia too.

Speech Dyspraxia

• Speech is difficult more as a motor coordination deficit rather than language but can look similar. Comprehension is less impaired. may be seen with right cortical strokes

Dysarthria and dysphonia

• Problems with articulation of speech and volume
• Ask patient to say "British constitution", "west register street"
• Problems with the movement of the mouth, palate, tongue such that speech is slurred and incoherent
• Multiple causes and only a small subset are neurological
• Not a "higher function" but usually just a motor/sensory issue

Causes: Non - neurological

• Disease of the oropharynx and palate e.g. poor dentition, poorly fitting dentures
• Cleft palate, oral cancers, infections, bone disease, joint disease
• Laryngeal disease - infections, cancers etc
• Functional/Hysterical - sometimes seen - whispering speech. Exclude organic causes first.

Causes Neurological

• Cerebellar Scanning type speech - cerebellar disease, drugs such as alcohol, excess phenytoin etc
• Motor weakness due to stroke or SOL affecting anywhere from the motor cortex where conscious oropharyngeal movements are organised to the cranial nerve nuclei. Can be due to anterior or posterior circulation strokes as well as SOL.
• Bulbar palsy - Nasal speech. fasciculating tongue decreased jaw jerk. Seen with polio, MND, neuropathies
• Pseudobulbar palsy - High pitched Donald duck speech, Increased jaw jerk, stiff spastic tongue. Seen with Bilateral stroke disease, MND
• Neuropathies affecting lower cranial nerves e.g. polio, GBS
• Myasthenia gravis can cause dysarthria and dysphonia