Neurogenic Voice Disorders Flashcards
Central Nervous System (CNS) & Peripheral Nervous System (PNS)
coordinates all laryngeal operations
Neural controls: Singing/Talking compared to Vegetative Function
CNS
sensory/motor areas of cerebral cortex, cerebellum, & basal ganglia contribute to voice production
CNS
Frontal & left temporal lobes involved with motor aspects of voice production
Bilateral parietal lobes provide sensory feedback regarding voice production
Premotor cortex, supplemental motor cortex, & Broca’s area contribute to planning & programming of phonation
Temporal lobes provide abilities to hear & process ongoing voicing via Heschl’s gyrus & Wernicke’s area
Pyramidal tract:
made up of long axons extend from the cortical neurons to the corresponding cranial nerve nuclei in the brainstem
Extrapyramidal tract:
neural transmissions to synapse with basal ganglia, across to the thalamus, subthalamus, cerebellum, and other structures
Neurotransmitters
They are several enzymes that transmit neural impulses among nuclei via white-matter nerves.
The basal ganglia depends on dopamine as a neurotransmitter.
Deficits: Neural transmission can be altered or stopped by isolated lesions. Many degenerative diseases of CNS can cause inhibition or overproduction of neurotransmitters. There can be a deficiency in the chemical transmitter, dopamine. This disturbance in the basal ganglia and extrapyramidal tract results in a Hypokinetic Dysarthria, Parkinson’s Disease.
Medications: Synthetic Dopamine is supplied to patient in the form of Levodopa and Sinemet.
Brainstem & Cerebellum
Projected fibers both extend from the pyramidal and extrapyramidal tracts extend anteriorly into the pons and posteriorly via the cerebral peduncle terminating once into the medulla oblongata.
Cerebellum wraps around the pons and cerebral peduncle, & has many interconnections with the pons, cerebral peduncle, medulla, & spinal cord.
Cerebellum is a regulator of the extrapyramidal tract coordinating sensory information (proprioceptive, kinesthetic, tactile, auditory, & visual) with
coordinated motor responses.
Deficits: Lesions of the cerebellum from trauma or disease causes speech symptoms of incoordination, Ataxic Dysarthria. Abrupt & unpredictable changes in resonance, pitch, and loudness may result.
Upper Motor Neuron (UMN) lesion
produces symptoms of hypertonicity (CVA) (hemiparesis or hemiplegia; however, not of the vocal fold)
Lower Motor Neuron (LMN) lesion
results in flaccidity & muscle atrophy which can cause vocal fold paresis.
PNS
Vagas, Cranial Nerve X
Superior Laryngeal Nerve & Recurrent Laryngeal Nerve both innervate the larynx
Acoustic, Cranial Nerve VIII ends in Heschl’s Gyrus in Temporal lobe
Sensory components of the Vagus affect voice, sensory innervation of the pharynx & larynx
Motor aspects of the Vagus affecting voice include innervation of velum; base of tongue;
Motor aspects of Vagus also affecting voice include superior, middle, & inferior pharyngeal constrictors; larynx; & autonomic ganglia of the thorax ( affecting respiratory aspects of phonation)
VAGUS nerve descends in a series of branches:
- 1st is the PHARYNGEAL BRANCH which is the most superior nerve branch: sensory & motor branch for the pharynx & soft palate
- 2nd branch is SLN which transmits sensory information from the base of tongue & mucous membrane of the SUPRAGLOTTIS; transmits motor innervation to part of the lower pharyngeal constrictor & cricothyroid muscles.
- 3rd branch is RLN which transmits sensory information from the SUBGLOTTIS; also transmits motor innervation to all the intrinsic laryngeal muscles except cricothryoid
SLN
tenses & relaxes True Vocal Folds as it provides motor innervation to the Cricothyroid (CT) muscle
Deficits: inability to elevate vocal pitch due to disease or trauma; unilateral CT paralysis results in extreme hoarseness or occasional diplophonia (disparate tension between two vocal folds)
RLN
position of the nerves in the neck make them susceptible to injury during surgery, ie. Carotid Endarterectomy. Left > Right
It is vital to abductory-adductory function of the true vocal folds. It innervates 4-5 muscles of the larynx.
Deficits: Paralysis of the thyroarytenoid muscle (TA) results from cutting or trauma of the RLN. Results in vocal fold atrophy, weakness in TVF approximation, mid TVF bowing, & dysphonia with subtle changes in pitch variation.
Deficits: Posterior Cricoarytenoid (PCA) paralysis is a unilateral abductor paralysis.
Lateral Cricoarytenoid (LCA) paralysis is TVF paralysis in the fixed, paramedian, abducted position.
Diagnoses Associated with Neurogenic Dysphonia:
- Vocal Fold Paralysis or Paresis,
- Parkinson’s Disease
- Huntington’s Disease
- Myasthenia Gravis
- Multiple Sclerosis
- Amyotrophic Lateral Sclerosis
- Traumatic Brain Injury
- Cerebral Vascular Accident
Unilateral Vocal Fold Paralysis
4 Categories: neoplastic (compression or infiltration) or traumatic (surgical or nonsurgical)
Glottic Incompetence
: one affected TVF can’t adduct completely to meet the normally mobile other TVF; affected paralyzed TVF is in the Paramedian Position for inspiration & expiration.
Severely Dysphonic or Aphonic
