Chapter 1 (MS)

Motor Speech Disorders

Occur when the motor nervous system is unable to properly plan, program, control, or execute the muscle movements required for speech production

Motor (Motor Speech Disorders)

Part of the motor system that controls motor movements

Speech (Motor Speech Disorders)

Communication through the use of vocal symbols involving the physical production of speech

Disorder

An abnormality of function

Dysarthria

A neuromuscular speech disorder caused by weakness, paralysis, incoordination, or abnormal muscle tone affecting the speech muscles

Speech subsystems affected by dysarthria

Respiration, phonation, resonance, articulation, and prosody

Common characteristics of dysarthria

Slurred speech, imprecise consonants, abnormal voice quality, and reduced speech intelligibility

Apraxia of Speech

A motor planning and programming disorder

Muscle weakness in apraxia of speech

The muscles themselves are not weak

Primary deficit in apraxia of speech

The brain has difficulty planning, sequencing, and programming the movements needed for speech

Characteristic of apraxia of speech #1

Inconsistent speech errors

Characteristic of apraxia of speech #2

Groping movements

Characteristic of apraxia of speech #3

Difficulty initiating speech

Characteristic of apraxia of speech #4

Increased errors with longer words

Characteristic of apraxia of speech #5

Disrupted prosody

Earliest descriptions of speech disorders

Found in the Hippocratic Corpus

Hippocratic Corpus

A collection of approximately 70 medical writings produced between 460–377 BC

Authorship of the Hippocratic Corpus

Although attributed to Hippocrates, scholars believe multiple physicians contributed

Topics included in the Hippocratic Corpus

Diseases, treatments, anatomy, patient case studies, and symptoms

Clinical observations made by Hippocratic physicians

Carefully observed patients, recognized speech changes after illness or injury, and connected speech problems with brain injury long before modern neuroscience

Accuracy of Hippocratic explanations

Their explanations were incorrect, but many observations were surprisingly accurate

Conditions associated with speech disorders in the Hippocratic Corpus

Fever, seizures, head injuries, strokes, and paralysis

Earliest recorded neurological communication disorders

Speech disorders following neurological disease or injury described in the Hippocratic Corpus

Speech symptoms described in the Hippocratic Corpus

Sudden speech loss, inability to speak, slurred speech, paralysis of one side, tongue weakness, and facial weakness

Modern disorders resembling Hippocratic descriptions

Aphasia, dysarthria, and apraxia

Speech disorder documentation during the Middle Ages and Renaissance

Physicians continued documenting speech disorders despite misunderstanding their causes

Conditions commonly described during the Middle Ages and Renaissance

Speech loss, paralysis, head injuries, skull fractures, falls from horses, and spear wounds

Importance of patient recovery observations

Allowed physicians to observe the recovery process

Significance of Middle Ages and Renaissance case reports

Demonstrated that physicians were excellent clinical observers

Modern diagnoses resembling Middle Ages and Renaissance descriptions

Dysarthria, aphasia, and apraxia

Ventricular Localization Theory

Early theory proposing that reasoning, language, and intelligence were located in the cerebral ventricles rather than brain tissue

Lateral ventricles according to the Ventricular Localization Theory

Received sensory information from the outside world

Third ventricle according to the Ventricular Localization Theory

Contained intellect and was responsible for thinking and reasoning

Fourth ventricle according to the Ventricular Localization Theory

Stored memory after information had been processed

Observation supporting the Ventricular Localization Theory

Deeper brain injuries produced more severe symptoms

Incorrect conclusion of the Ventricular Localization Theory

The ventricles controlled reasoning and speech

Galen (130–200 AD)

Strong supporter of the Ventricular Localization Theory

Reason Galen supported the Ventricular Localization Theory

Believed deeper wounds caused greater impairment, indicating the ventricles housed the mind

Influence of Galen's theory

Remained influential for centuries despite being incorrect

Leonardo da Vinci's view of the Ventricular Localization Theory

Accepted the theory and believed the ventricles housed intellect, reasoning, and speech

Vesalius

Anatomist who challenged the Ventricular Localization Theory

Reason Vesalius challenged the Ventricular Localization Theory

Animal ventricles closely resembled human ventricles

Vesalius' argument against the Ventricular Localization Theory

If ventricles controlled intelligence, animals should possess human reasoning

Contribution of Vesalius

Helped discredit the Ventricular Localization Theory

Meningeal Theory

Theory proposing that the meninges controlled sensation, movement, reasoning, and speech

Functions attributed to the meninges according to the Meningeal Theory

Sensation, movement, reasoning, and speech

Evidence supporting the Meningeal Theory

Physicians noticed many patients with head injuries also had damaged meninges

Incorrect conclusion of the Meningeal Theory

Speech deficits were caused by meningeal damage rather than injury to brain tissue

Duration of popularity of the Meningeal Theory

Remained popular through the 16th century

Beginning of modern neurology

The 1800s

Changes in neurological research during the 1800s

Physicians produced detailed case studies, neurological examinations, and careful clinical observations

Recognition of motor speech disorders in the 1800s

Gradually became recognized as specific neurological conditions

James Parkinson (1817)

Published An Essay on the Shaking Palsy

Importance of An Essay on the Shaking Palsy

First detailed description of Parkinson disease

Speech characteristics described by James Parkinson

Reduced articulation, drooling, reduced voluntary movement, rigid posture, and increasingly difficult speech

Relevance of Parkinson's observations today

They remain recognizable in modern Parkinson disease

Jean-Martin Charcot

Known as the Father of Modern Neurology

Neurological diseases studied by Charcot

Parkinson disease, multiple sclerosis, and amyotrophic lateral sclerosis (ALS)

Speech characteristics of multiple sclerosis described by Charcot

Slow, scanning, syllable-by-syllable speech interrupted by pauses

Modern interpretation of Charcot's MS speech description

Recognized as ataxic dysarthria, although many individuals with MS present with mixed dysarthria

Marie and Katwinkel (1897)

Studied speech and language following right hemisphere lesions

Contribution of Marie and Katwinkel

Described another form of dysarthria, expanding knowledge of motor speech disorders

Carl Wernicke

Made important contributions to aphasia, speech production, and language localization

Speech disorder resembling Wernicke's descriptions

Apraxia of speech

Limitation of Wernicke's description of apraxia

He did not identify it as a separate disorder

Darley and colleagues (1960s)

Made one of the greatest contributions to modern motor speech pathology

Primary focus of Darley and colleagues

Systematically studied dysarthria

Contribution of Darley and colleagues to dysarthria

Developed dysarthria classifications and connected speech characteristics with neurological lesions

Major contributions of Darley and colleagues

Established perceptual speech characteristics, dysarthria classifications, neurological correlates, and terminology still used today

Examples of terminology introduced by Darley and colleagues

Scanning speech, ataxic speech, spastic speech, and flaccid speech

Importance of Darley and colleagues' work

Remains the foundation of modern motor speech disorder assessmen