Neurology of Speech

what is speech?

a dynamic motor process where respiration, articulation, phonation, and resonance is coordinated in order to produce strong speech sounds

direct motor pathways

-lateral corticobulbar tract

-lateral corticospinal tract

-responsible for gross voluntary motor movement

both lateral corticobulbar tract and lateral corticospinal tract used for

speech

lateral corticobulbar tract

-cortex to brainstem

-controls contralateral head via cranial nerves

lateral corticospinal tract

-cortex to spine

-controls contralateral body via spinal nerves

upper motor neurons

neurons within the corticospinal and corticobulbar tract

lower motor neurons

cranial and spinal nerves

where do upper motor neurons originate?

cerebral cortex and travel down to brainstem / spinal cord

where do lower motor neurons originate?

in the brainstem or spinal cord and go to muscles and glands

motor speech system levels

-conceptual

-motor and linguistic planning

-motor programming

-motor control circuits

-direct motor pathway

-indirect motor pathway

-motor control circuits

-final common pathway

-sensory system

conceptual level

-ideas thoughts and feelings

-what we want to say or express

motor planning

plans and arranges phonemes for physical production

what areas are important in motor planning?

-brocas

-premotor cortex

-supplementary motor cortex

programming

-execution of phonemes in real time using discrete movements of tongue and lips

important areas for programming

-supplementary motor area

-basal ganglia

-cerebellum

apraxia of speech

-motor speech disorder (at planning or programming level)

-brocas area

-searching and groping for articulatory placement with no musculature abnormality

-inconsistent errors (instability of word production)

what percent of motor speech disorders does apraxia of speech make up?

8%

what percent of motor speech disorders does dysarthria of speech make up?

92%

dysarthria of speech

Speech disorders caused by neuromuscular dysfunction, that is, muscle weakness, incoordination, paralysis due to damage to central and/or peripheral nervous system pathways.

motor control circuit (basal ganglia)

regulates motor functioning, especially tone and posture for smooth and precise movement

damage to basal ganglia can result in

apraxia

which neurotransmitter does the basal ganglia use?

dopamine

extrapyramidal

Outside the pyramidal tracts, with origin in the basal ganglia. These cell bodies are involved with starting, stopping, and smoothing out movements

basal ganglia is an indirect

motor pathway

motor control circuit (cerebellum)

coordinates muscle movements so they are skilled and sequential

damage to motor control circuit (cerebellum) can result in

ataxic dysarthria

ataxic dysarthria

a motor speech disorder caused by cerebellar damage, resulting in uncoordinated, "drunken," and slurred speech

the cerebellum is both an

indirect and extrapyramidal pathway

ataxic dysarthria

-damage to cerebellum

-harsh voice, monopitch, loud voice

-imprecise consonants and irregular breakdown in articulation (drunk sounding)

- "without order"

direct motor pathways are responsible for

gross voluntary motor movement

hypertonia

abnormal increase in muscle tension

spastic muscles

-type of hypertonia

-uncontrollable muscle tightness due to nervous system damage

Hyperreflexia

-overactivity or exaggeration of reflexes

-characterized by faster or more intense response to stimuli

Babinski sign

The toes flex upward when sole of foot is stimulated, indicating motor nerve damage (over 12 months of age)

atrophy

wasting away due to lack of stimulation or use

fasciculations

small involuntary rapid muscle twitches due to spontaneous contraction

symptoms of upper motor neuron damage

-spastic muscles

-no fasciculations

-positive babinski sign

-no atrophy

symptoms of lower motor neuron damage

-flaccid muscles

-fasciculations

-no babinski sign

-marked atrophy

flaccid dysarthria

-LMN affected

-weak muscles

-breathy voice

-monopitch

-hypernasality

-short phrases

-imprecise consonants

spastic dysarthria

-UMN affected

-stiff, rigid muscles

-harsh/strained voice

-monopitch

-hypernasality

-slow speech rate

-imprecise consonants

dysarthria

speech that is unclear, slurred, or uncoordinate due to CNS or PNS problems affecting respiration, phonation, articulation, and resonance

indirect motor system

-controls involuntary movements of posture, muscle tone, and reflexes

-includes many tracts

-AKA extrapyramidal system

indirect motor system stops at

-basal ganglia

-cerebellum

indirect motor system damage can result in

dyskinesias: disordered movements

-tremors

-chorea

-athetosis: slow writhing movements

-dystonia: involuntary muscle contractions, twisting movement

hyperkinetic dysarthria

-damage to basal ganglia

-indirect motor system damage

- harsh voice, monopitch, loud voice, involuntary movement

-huntington's disease

hypokinetic dysarthria

- issues in substantia nigra (dopamine)

-indirect motor system damage

-breathy voice, monopitch, imprecise consonants

-parkinson's disease

final common pathway

- last leg of a motor signals journey

-where lower motor neuron connects to muscle

cranial nerves used for power for speech and tonal qualities

-trigeminal (5)

-facial (7)

-glossopharyngeal (9)

-vagus (10)

-accessory (11)

-hypoglossal (12)

Lower motor neuron lesions can cause paresis or paralysis of the

-larynx, velum, and pharynx (Vagus nerve)

if client has a LMN lesion or damage resulting in a paralyzed right vocal cord the lesion would be on the

right side

if client has an UMN lesion or damage resulting in a paralyzed right vocal cord the lesion would be on the

left side

lower motor neuron lesions can cause difficulty with

shoulder shrug and head turn (accessory nerve 11)

unilateral lower motor neuron facial nerve damage results in

entire face affected on same side of damage

LMN damage to hypoglossal nerve results in

tongue pushing towards lesion

UMN damage to hypoglossal nerve results in

tongue pointing away from lesion

sensory tracts

-dorsal column: fine touch

-spinothalamic: pain, pressure, temp

-spinocerebellar: proprioception