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74 MOTOR SPEECH DISORDERS: DIAGNOSIS AND TREATMENT
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trigeminal cranial nerve. When the jaw muscles on one side
of the face are weaker than on the other, the jaw might
deviate to the weaker side when the mouth is opened widely.
10. Is the patient able to move the jaw to the right and left? An
inability to do this suggests bilateral weakness of the jaw
muscles. However, hesitations or groping on this task also
might indicate a nonverbal oral apraxia.
11. Is the patient able to keep the jaw closed while the exam-
iner attempts to open it? This task assesses the strength of
the muscles that elevate the jaw, primarily the masseter and
temporalis. The examiner’s ability to manually open the jaw
suggests bilateral weakness in these muscles—possibly the
result of bilateral damage to the trigeminal cranial nerve.
12. Is the patient able to keep the jaw open while the examiner
attempts to close it? This task examines the muscles that
open the jaw. These muscles are the digastricus, mylohyoid,
and geniohyoid. If you can manually close the jaw while the
patient attempts to keep it open, bilateral weakness of these
muscles is indicated.
Tongue at Rest and During Movement
The tongue is one of the key articulators. Impairments to its structure or function can have signicant effects on the articulation of
speech sounds. It is especially important to evaluate the tongue at
rest and during movement. Both positions can provide important
diagnostic information. Most of the assessment tasks in this section examine the function of the hypoglossal cranial nerve (XII),
which innervates the intrinsic and extrinsic muscles of the tongue.
If groping tongue movements are noted in any of these tasks, be
sure to complete the apraxia section of the evaluation.
Explanation of Specific Tasks
1. Does the size of the tongue appear normal at rest? When
damage occurs to lower motor neurons (e.g., those in the
cranial nerves), the muscles normally innervated by those
neurons will shrink because of atrophy. If there is unilateral
damage to the hypoglossal nerve, the half of the tongue on
the damaged side can take on a furrowed, shrunken appearance. When this damage occurs to both the left and right
hypoglossal cranial nerves, the muscle atrophy will affect the
whole tongue, leaving the entire tongue shrunken.
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2. Is the tongue symmetrical at rest? If damage to the hypo-
glossal cranial nerve (XII) is restricted to only one side, the
resulting atrophy will be restricted to that same side. The
tongue will consequently have an asymmetrical appearance,
with the unaffected side looking normal and only the other
side demonstrating the atrophy.
3. Are fasciculations present when the tongue is at rest?
Fasciculations are small involuntary movements that may
occur in a muscle when motor innervation has been lost
through damage to lower motor neurons. If fasciculations
are present after damage to the hypoglossal cranial nerve,
you will see small, nonrhythmic dimpling along the surface
of the tongue, or you might see subtle “wormlike” move-
ments of the entire tongue.
4. Does the tongue remain still while at rest? In addition to
fasciculations, other conditions can result in involuntary
movements when the tongue is supposedly at rest. Hyperki-
netic movement disorders such as chorea and dystonia could
cause the tongue to involuntarily protrude, retract, rotate,
and move side to side. Hyperkinetic movement disorders are
discussed in Chapter 9.
5. Is the patient able to protrude the tongue completely? This
assesses range of motion for the posterior bers of the
genioglossus muscle, which protrudes the tongue, and the
vertical and transverse intrinsic muscles, which give the tongue
its “pointed” shape when protruded. If there is bilateral
weakness of these muscles, the tongue can be protruded
only a limited distance, if at all. If the weakness is unilat-
eral, the protruded tongue will deviate to the affected side.
This deviation to the affected side is the result of unequal
contractions of the left and right sides of the genioglossus
muscle in the tongue. The contractions of the unaffected
side of this muscle will overcome the weakened contractions
on the other side of the muscle, thereby causing the tongue
to point to the affected side. You can check the strength of
tongue protrusion by having the patient push the tongue
against a tongue blade held rmly in front of the mouth.
6. Can the patient keep the tongue tip at midline while the
examiner pushes the tongue to the left and right? This task
checks the strength of several tongue muscles, including the
genioglossus, superior longitudinal, and inferior longitudinal
muscles.
7. Is the patient able to touch the upper lip with the tongue
tip? Here you are assessing the range of motion of the
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tongue protrusion muscles (genioglossus, vertical, and
transverse intrinsic muscles) and the superior longitudinal
muscle, which elevates the tongue tip.
8. Can the patient keep the tongue tip pressed against the
inside of the cheek as the examiner pushes the cheek
inward? This is an examination of strength for a number
of tongue muscles, primarily the longitudinal muscles. The
tongue tip will deviate to the left or right with simultaneous
contraction of either the left or right superior and inferior
longitudinal muscles, respectively. Unilateral weakness in
these muscles is evident through comparison of the amount
of outward force the tongue is able to apply to either the
right or left cheek.
9. Can the patient move the tongue from side to side? This
task examines range of motion for the superior and inferior
longitudinal muscles. These muscles are used to lateralize
the tongue from one corner of the mouth to the other.
Reduced lateral tongue movement to one side of the mouth
will reveal unilateral weakness of these muscles.
Velum and Pharynx at Rest and During Movement
This section of the evaluation looks at the structure and function of
the velum and pharynx. Most of the muscles in these structures are
innervated by the vagus cranial nerve (X). It is difcult to obtain
much in-depth information about these structures in this portion
of the examination because they are difcult to see clearly. In
truth, you are only able to look for the most obvious anatomical
and functional deviations. Additional information about the velum
and pharynx can be obtained in later sections of this examination.
Explanation of Specific Tasks
1. Does the velum rise symmetrically each time the patient
says /a/? Have the patient repeat /a/ four or ve times. Make
sure there is a brief pause between each production. This
will allow the velum to return to its resting position after
each /a/, giving you a better opportunity to observe the full
range of velar movement. A normally functioning velum and
pharynx work together to close the velopharyngeal port
during the production of nonnasal sounds. You should see
the entire velum rise promptly just before phonation. At the
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same time, the sides and back of the upper pharynx should
move slightly inward to meet the rising velum.
In cases of moderate to severe bilateral weakness of the
velum and pharynx, you should be able to observe reduced
speed and range of motion of these structures when the
patient repeats /a/. However, these reductions can be difcult to detect visually when there is mild bilateral weakness.
When there is unilateral muscular weakness of the velum
and pharynx, the unaffected side should demonstrate nearly
normal movement. The impaired side will show little or no
movement. The uvula will be pulled toward the stronger,
unaffected side as that side of the velum rises.
2. Is there a pharyngeal gag reex when the back wall of
the pharynx is touched? The gag is a protective reex.
Its purpose is to clear the upper pharynx of an obstruction that might threaten to block the airway. Testing this
reex assesses the neuromuscular loop that starts with the
sensory nerves in pharyngeal muscles and tissue. When the
sensory nerves in the pharynx are stimulated by the touch
of a foreign object, they send a sensory impulse through
the glossopharyngeal cranial nerve (IX) to the brainstem.
From the brainstem, a motor impulse is sent directly to the
pharyngeal and velar muscles via the vagus cranial nerve
(X), which causes those muscles to contract rapidly. Damage
to any portion of this loop leads to a decreased or absent
gag reex. Note, however, that many individuals without
neurologic damage are quite insensitive to pharyngeal
stimulation and do not readily demonstrate a gag reex.
Laryngeal Function
The function of the larynx cannot be observed directly. To actually
observe the actions of the larynx, you need instrumentation, such
as a laryngeal mirror or a exible nasoendoscope. However, some
procedures indirectly assess laryngeal function. The following three
tasks evaluate the strength and range of movement of the laryngeal
adductor and abductor muscles. Other tasks later in the evaluation
assess phonation, which is a key function of the larynx.
Explanation of Specific Tasks
1. Is the patient able to produce a sharp cough? This task
assesses the strength of vocal-fold adduction. Producing a
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sharp cough requires tight vocal-fold adduction for building
up subglottic air pressure. When adduction is weak, the
cough will have a soft, breathy quality because the adductor
muscles are not strong enough to hold air in the lungs. In
some instances, this task also assesses the adequacy of the
respiratory system. If the respiratory muscles are not strong
enough to provide a forced exhalation of air, the resulting
cough also will have a soft, breathy quality. The next step
of this evaluation presents a procedure for determining
whether a breathy cough is the result of laryngeal or respiratory weakness.
2. Can the patient produce a sharp glottal stop? In this task,
the patient is asked to produce an abrupt glottal stop (or a
forceful grunt), to assess the strength of vocal-fold adduction. Duffy (2020) recommended this procedure to help
determine whether a weak cough is the result of inadequate
vocal-fold adduction or poor breath support. If a patient
who produces a weak cough can bring the vocal folds
together with enough force to make a sharp glottal stop,
then he or she has sufcient adductor muscle strength to
close the glottis tightly. This would suggest that a weak
cough is the result of poor breath support, not adductor
muscle weakness.
3. Is inhalatory stridor present? If abductor muscle paralysis
prevents the vocal folds from being abducted completely,
inhalatory stridor— a breathy wheeze that can be heard
during inhalation—could be present. This vocal-fold
abductor paralysis may be caused by unilateral or bilateral
damage to the vagus cranial nerve. In severe cases, the
stridor is actually a phonation on inhalation. Although
stridor might be evident on quiet breathing, most patients
will need to take a quick, deep breath before it will be
noticeable.
Auditory-Perceptual Evaluations of the Motor Speech Mechanism
In most cases, the ear is the best instrument for evaluating decits
of the motor speech mechanism. A clinician with an experienced
ear can often make a quick, accurate diagnosis based only on the
acoustic characteristics of a patient’s speech. The importance of
developing a sharp ear for the assessment of motor speech disorders cannot be overstated. After all, what a listener hears provides
the ultimate judgment of whether speech production is defective.
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Accordingly, most of the remaining evaluation tasks rely on a clinician’s perceptual analysis of a patient’s speech.
Phonatory-Respiratory System
It is logical to assess the phonatory and respiratory components of
the speech mechanism at the same time because normal phonation
is so dependent on an adequate supply of subglottic air pressure. In
this protocol section, the clinician will determine the length of time
the patient can prolong an /a/. Listen critically to the quality, pitch,
and loudness of the patient’s phonation, because each of these
characteristics can provide much useful diagnostic information.
Explanation of Specific Tasks
1. “Take a deep breath and say /a/ as long, steadily, and clearly
as you can.” This task assesses both the adequacy of breath
support and vocal-fold adduction for phonation. If there is
too little breath support, there will be inadequate subglottic
air pressure to prolong the /a/ for 15 s. If the vocal folds
are not adducted fully, excess amounts of air will escape
from the larynx during phonation. This wastes subglottic
air and lessens the length of the phonation. To determine
whether a reduced length of phonation is the result of poor
breath support or incomplete vocal-fold adduction, check
the results from the previous section of the evaluation,
which provided for assessment of the adequacy of vocal-fold
adduction.
2. Is there a latency period between the signal to say /a/ and
the initiation of phonation? If there is a delay, it could be
the result of weakness in the phonatory-respiratory system.
It could also be the result of a problem of sequencing
the motor movements needed to produce the /a/. Such
sequencing difculties are characteristic of apraxia, which is
assessed in greater detail later in the evaluation.
3. Quality, pitch, and loudness of phonations can be evalu-
ated. In a normal phonation, the vocal quality is steady,
even, smooth, and clear. The presence of hypernasality
indicates inadequate velopharyngeal closure. Breathiness
can indicate incomplete vocal-fold adduction during phonation. Harshness is an abnormal vocal quality that is caused
by the friction of air being passed through vocal folds that
are almost fully adducted. Diplophonia is the simultaneous
production of two pitch levels during phonation. In motor
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speech disorders, it is usually the result of unilateral vocalfold paralysis.
Pitch can be affected by motor speech disorders. It
might be too low, as in spastic dysarthria and several of the
hyperkinetic dysarthrias. There could be a tremor in the
phonations, which is present in such disorders as essential
voice tremor, one of the hyperkinetic dysarthrias. Pitch
breaks are sudden shifts in pitch during phonation. These
are heard most often in accid and spastic dysarthria.
Loudness can be affected by motor speech disorders.
The involuntary movements in hyperkinetic dysarthria can
cause excessive loudness variations during phonations. Poor
respiratory support or inadequate phonation can cause
decreased loudness, perhaps most often heard in accid and
hypokinetic dysarthria.
Resonation System
This portion of the evaluation assesses velopharyngeal function.
Weakened or paralyzed velar muscles result in incomplete velopharyngeal closure, which is heard perceptually as hypernasality. In
motor speech disorders, hypernasality is most frequently a symptom of accid or spastic dysarthria. Hyponasality, the counterpart
of hypernasality, is rarely present in the speech of individuals with
dysarthria or apraxia of speech. Because other tasks in this motor
speech evaluation have already evaluated elements of the resonatory system (velar movement and hypernasal voice quality), the
ndings of the following two tasks should be combined with the
results of the previous tasks to arrive at the most accurate assessment of the patient’s velopharyngeal function.
Explanation of Specific Tasks
1. “Take a deep breath and say /u/ for as long as you can.”
On this task, ask the patient to prolong the high, back
vowel /u/, which usually maximizes velopharyngeal closure.
While the patient says /u/, hold a small mirror rst under
one nostril and then under the other. Nasal emission of air
during this phonation will be revealed as fogging of the
mirror. You should disregard any momentary fogging of
the mirror at the very beginning or end of the phonation.
However, the mirror should remain clear during the middle
of the phonation.
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2. “This time I’m going to squeeze your nose. Don’t let it
bother you.” Here the clinician makes a perceptual judgment
of whether hypernasality is present during the prolongation
of /u/. By alternately squeezing and releasing the nostrils
while the patient is producing /u/, you are intermittently
stopping any nasal airow during phonation. If there is
hypernasality, you will hear a difference in resonance as the
patient’s nose is squeezed and released.
Combined Systems (Phonation, Respiration,
Resonation, and Articulation)
AMR is an assessment of a patient’s ability to move the articulators
rapidly yet smoothly in a repetitive motion. It also is known as the
diadochokinetic rate. AMRs are a key evaluation task for motor
speech disorders. They provide valuable information on the speed
and rhythm of syllable production. AMRs are very important in a
motor speech evaluation because individuals with different types
of dysarthria typically perform differently on this task.
n Individuals with accid and spastic dysarthria usually have
slow and regular AMRs.
n Individuals with ataxic and hyperkinetic dysarthria often have
slow and irregular AMRs.
n Some individuals with hypokinetic dysarthria have AMRs that
are more rapid than normal. In certain individuals with this
dysarthria, the AMRs are said so quickly that their articulation
of the phonemes is blurred.
By carefully analyzing the patient’s AMR performance, one can
often obtain important diagnostic information about the patient’s
dysarthria.
Explanation of Specific Task
“Take a deep breath and say ‘puh, puh, puh’ as long, as fast, and as
evenly as you can.” After saying these directions, be sure to demonstrate for the patient how the syllables should be produced. To
obtain an accurate count of the patient’s AMRs, it is important to
always use some type of instrumentation during this task, either a
computer, a tape recorder, or some other recording device. Even
experienced clinicians have difculty timing and counting syllable
repetitions if the patient’s performance is not recorded. In this
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task, you are primarily listening for the speed and rhythm of the
productions, but loudness, pitch, and articulation also are important. For example, excessive variations in syllable loudness are
typical of ataxic and hyperkinetic dysarthria; blurred articulation
can be a characteristic of hypokinetic dysarthria.
SMR is a task that assesses a patient’s ability to move the articulators in a rapid, smooth sequence of motions. Typically, SMRs are
more difcult to perform accurately than AMRs. This task is often
useful in bringing out the symptoms of apraxia of speech. It is not
unusual to have individuals with apraxia of speech complete the
AMR task successfully but be unable to complete even the rst
attempt at the SMR sequence. (This is not to suggest, however, that
all individuals with apraxia of speech are able to complete the AMR
task successfully; many have difculty with both tasks.) Some of
the errors individuals with apraxia of speech might demonstrate
on the SMR task include delays in beginning the task, phoneme
substitutions, incorrect sequencing of syllables, and articulatory
groping for the correct phoneme placement.
“Now I want you to make those three sounds together.” As with
the AMRs, it is important to record the patient’s trials on the SMR
task to obtain an accurate syllable count. One should also be sure to
demonstrate for the patient how the syllables should be produced.
Stress Testing of the Motor Speech Mechanism
This task screens for myasthenia gravis, a disorder that causes
rapid fatigue of the muscles during a sustained motor activity (see
Chapter 4). To test for myasthenia gravis, ask the patient to count
quickly from 1 to 100. Listen for a relatively rapid deterioration of
articulation, resonance, or phonation while the patient is counting.
Typically, there will be a recovery of muscle function after a rest
period, but performance will decline if the muscles again are taxed
in a sustained activity.
Testing for Nonverbal Oral Apraxia
Apraxia is a disruption in the ability to voluntarily sequence complex movements accurately. It is not the result of muscle weakness, reduced range of motion, or a cognitive inability to plan the
target movement. Apraxia is a problem in timing and accuracy of
a complex movement that has already been planned by the higher
centers of the brain. Two types of apraxia affect the speech musculature: nonverbal oral apraxia and apraxia of speech. Nonverbal
oral apraxia is a disruption in the sequencing of oral movements
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that are nonverbal, sometimes described as “vegetative movements.”
Examples of nonverbal oral movements include smiling, puckering
the lips, protruding the tongue, and biting the lower lip. Individuals with this type of apraxia will demonstrate hesitations, groping,
and revisions when attempting to perform nonverbal oral movements. It is possible for someone to have nonverbal oral apraxia
but not have apraxia of speech. It is also possible for someone to
have apraxia of speech but not nonverbal oral apraxia. Usually,
however, these two types of apraxia are co-occurring disorders—if
one is present, so is the other.
Explanation of Specific Task
“Now I want you to do some things.” These tasks assess the patient’s
ability to perform voluntary nonverbal oral movements. Do not
demonstrate the desired movement for the patient immediately
after reading the command. Wait until the patient has attempted
the task independently before demonstrating the movement. The
patient’s performance is graded on an 11-point scale, which ranges
from a prompt response to no oral movement. Such a scoring system allows the clinician to obtain a much more detailed picture of
a patient’s performance than a simple right or wrong scoring. You
should become familiar with the 11 points before administering
this portion of the evaluation.
Testing for Apraxia of Speech
Apraxia of speech, a disruption in the timing and accuracy of voluntary movements for speech production, is the other type of apraxia
that can affect the speech musculature. Individuals with apraxia of
speech often demonstrate pauses and distortions when they are
attempting to speak, especially when trying to say multisyllabic
words. These errors can include a slow rate of speech, abnormal
prosody, groping to position the articulators correctly, and distorted
phonemes. Interestingly, both automatic and emotional speech can
be relatively free of apraxic errors, which means that such verbal
tasks as counting, uttering an expletive, or replying to a social
greeting might be produced more accurately. Apraxia of speech is
discussed in more detail in Chapter 11.
Explanation of Specific Tasks
1. “Say these words for me.” This task has the patient repeating
or reading a list of words. The list starts with a two-syllable
word and progresses to a complex sequence of increasingly
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