Speech Pathology
Managing Speech Disorders:
An Introduction to Speech Pathology and Resonance Disorders
by John E. Riski, Ph.D.
Speech Pathologists and Resonance Disorders
Hypernasality: a voice or resonance disorder?
Hypernasality is often mislabeled as a voice disorder. In fact, it is a resonance
disorder! Voice disorders are caused by dysfunction of the larynx. Hypernasality
is caused by a dysfunction of the velopharyngeal mechanism.
“Speech therapy” for voice disorders involves voice re-education and vocal hygiene
programs. “Speech therapy” for mild hypernasality involves articulation therapy
techniques. Hypernasality usually requires physical management, such as surgery
or prosthetics.
Medical management for voice disorders is by otolaryngologists (ear, nose and
throat specialists) and surgical management for hypernasality is by a plastic
surgeon or craniofacial surgeon who participates on a cleft palate-craniofacial
team.
What is “velopharyngeal incompetence” (VPI)?
- Velopharyngeal incompetence or VPI is the inability of the velum (soft palate)
and related musculature to close the nasopharynx, separating the oral and nasal
cavities for the production of oral consonants. A VPI can be caused by a deficiency
of the velum or an increased size of the pharynx. The latter is difficult to diagnose
without imaging.
- A VPI usually has a physiological origin and requires physical management such
as surgery or prosthesis.
- A VPI may have a “functional” origin from misuse of the velum. Some unique misarticulations
such as the “nasal snort” (now more correctly labeled a “posterior nasal fricative”)
involve a “functional misuse of the velum” and will only resolve with appropriate
speech therapy.
- A VPI might also be considered when the nasopharynx is obstructed and cannot
open adequately for breathing and producing the three nasal consonants (resulting
in hyponasality). The cause may be hypertrophied adenoids, aggressive pharyngoplasty
or narrowed nasopharynx from other causes. This is difficult to diagnose without
imaging.
What are possible symptoms of VPI?
- Hypernasality
- Hyponasality
- Nasal air escape
- Reduced oral pressure for consonants
- Compensatory Articulation including:
— Glottal stops
— Pharyngeal fricatives
— “Nasal snorts” (more correctly labeled “posterior nasal fricatives”)
- Velopharyngeal function is the functional relationship between the velopharyngeal
musculature and the pharyngeal space. Both should be evaluated.
What causes resonance disorders?
The primary causes of hypernasality are structural deficits, neurological disorders
and “faulty learning.”
Structural deficits include:
Cleft Palate (with or without cleft lip) — These are usually easy to identify. The presence of a cleft palate identifies
someone who has an increased chance of hypernasal speech.
- There is approximately a 20% incidence of hypernasality after initial palate
closure.
- The role of the speech pathologist is to identify these children ASAP!
- Earlier treatment of VPI seems to allow for better overall speech.
- Large VPIs are treated early; borderline VPIs are treated later.
Submucous Cleft Palate — This is often more difficult to identify. The most obvious forms include a
bifid uvula, intact mucosa but noticeable separation of muscle in the midline
of the soft palate, and absent posterior nasal spine of the hard palate with obvious
forward attachment of the soft palate muscles. The less obvious forms can be detected
only by measuring the thickness of the soft palate on radiographic studies or
the continuity of muscle on the nasal surface of the soft palate by endoscopic
examination.
Deep Pharynx — This is the most difficult to recognize since the deficit is in the size of
the nasopharynx and not of the soft palate. The soft palate may appear normal
by oral exam. The velopharyngeal deficit can be identified only by lateral radiographs
or lateral fluoroscopy. The primary features are the speech characteristics of
hypernasal resonance, nasal air escape and possibly “cleft palate-like misarticulations”
without obvious physical deficits. Other characteristics are nasal regurgitation
as a newborn, difficulty nursing and delayed, hypernasal speech with normal language
development. The speech-language pathologist is extremely important in the ultimate
diagnosis and referral for appropriate evaluation and management of disorders
of the deep pharynx. Speech deficits are the primary characteristics.
- VPI is often not diagnosed or diagnosed late because the palate appears normal
and the pharynx is not evaluated.
- When diagnosed after speech has begun, sparse adenoid mass may be a factor.
- Hypernasality is the primary presenting factor.
- Hypernasality may be present from onset of speech — some children do not grow
adenoids.
- After adenoidectomy — deep nasopharynx is unmasked (velo-pharyngeal mechanism seems able to adjust
to slow involution but not the sudden increase with adenoidectomy).
Neurological causes or dysarthrias include:
Upper Motor Lesions
Upper motor deficits include head injury, cortical stroke, cerebral palsy, brain
tumors or irradiation. In this “spastic dysarthria,” all speech subsystems (respiration,
laryngeal, velopharyngeal and articulatory) may be affected to some degree. These
may lead to a “spastic weakness” of the speech mechanism including the velopharyngeal
mechanism. Deficits are bilateral and characterized by increased muscular tone.
Instrumental evaluation is helpful to measure the function of each subsystem and
its contribution to the overall speech deficit.
- Spasticity and increased tone are the chief characteristics (spastic weakness).
- May be congenital or adventitious (cerebral palsy or trauma).
- Deficits are bilateral.
- Hypernasality may be accompanied by harsh (spastic quality) voice quality.
Lower Motor Lesions
Lower motor deficits such as lesions to the Xth cranial (Vagus) nerve, isolated
lesions to the pharyngeal branch of the Vagus, or brainstem stroke or tumor can
cause a flaccid dysarthria characterized by decreased muscular tone. Isolated
cranial nerve deficits cause unilateral muscular deficits. When the lesion to
the Vagus is above the pharyngeal branch, the soft palate and larynx will demonstrate
deficits on the same side and the resulting speech will be hypernasal and breathy.
A brainstem stroke or tumor may affect more than one cranial nerve.
- Flaccidity and atrophy are the major characteristics.
- May be congenital as in Moebius Syndrome.
- May be adventitious as in surgical or accidental trauma to peripheral nervous
system.
- Deficits are usually unilateral. Both the larynx and velum should be checked
if one is paralyzed.
Faulty Learning: “Functional VPI” or “Sound/Specific VPI”
Faulty learning is not truly a velopharyngeal deficit, but rather represents
a unique misarticulation.
The terms “Functional VPI” and “Sound/Specific VPI” have been used in the literature
to label this disorder. A “Functional VPI” can be confusing to diagnose because
it presents with nasal air escape just as structural and neurologic deficits.
The nasal air escape is caused by forcing the breath stream through a constriction
of the velum against the posterior pharyngeal wall while the tongue stops oral
air flow. This misarticulation was previously labeled a “nasal snort.” The physiology
of this misarticulation is now better understood and more appropriately labeled
a “posterior nasal fricative.” It is usually substituted for the sibilant (“s”
and “z”) and affricate (“ch” and “dg”) sounds.
- Since velopharyngeal function is normal, the stop-plosives do not have nasal
air escape and resonance is normal.
- The velum is neurologically and anatomically capable of closure at the time of
evaluation.
- May represent a history of transient VPI, now resolved.
- Found in children with sensori-neural hearing loss or chronic conductive hearing
loss.
- Will not respond to surgery or prosthetic management. Requires speech therapy.
What kinds of patients benefit from an instrumental evaluation of speech disorders?
Patients with the following diagnoses may benefit from instrumental assessment:
- Cleft palate
- Craniofacial and related disorders
- Dysarthria
- Traumatic brain injury
- Brain tumor
- Neurologic disease
- Cerebral palsy
- Congenital or acquired anomalies
- Voice disorders
What kinds of speech symptoms are presented by these patients?
Patients may present with a number of symptoms including:
- Hypernasality (cleft palate, post tonsillectomy/adenoidectomy, neuromotor disorder
— acquired or congenital)
- Hyponasality
- Articulation
- Swallowing disorders
- Hoarseness
- Dysarthria
- Poor response to speech therapy
- Difficult-to-diagnose speech problems
What computer-based instruments are used to analyze speech?
- Pressure flow
- Nasometry
- Acoustic analysis instruments
How can instrumentation and imaging help with speech disorders?
They improve understanding of voice and resonance disorders through direct visualization.
- The mechanisms of velum and larynx are not visible from an oral exam but can
be observed through endoscopy, radiography or fluoroscopy.
- Our ears may detect gross disturbance but cannot reliably discern subtleties
of speech production. Instrumentation is able to define the subtleties of speech.
- Instrumentation yields quantifiable, reproducible results.
How does computerized instrumentation assist the evaluation?
Special instrumentation makes diagnosis and treatment more accurate and more
efficient:
- Assessment with computerized instruments is objective and more accurate than
perceptual judgments alone. Speech performance can be compared to standardized
peer/group norms.
- Pre and post measures make outcomes easier to evaluate.
- Computers can measure several speech qualities simultaneously, e.g., pressure
flow, voice and resonance measures can be measured together.
- Objective measures can be taken during diagnostic/trial therapy to assess the
effectiveness of a therapeutic technique.
What instruments are used to image the vocal tract?
- Flexible endoscopy
- Videofluoroscopy
- Cephalometric radiography
How does imaging assist the evaluation?
- Allows us to view the structures and functions of the speech mechanism that are
not visible during oral exam.
- Natural speech can be observed.
- Response to speech therapy can be observed.
- Information from lateral fluoroscopy/radiography and endoscopy has improved the
outcome of surgery for hypernasality.