Unilateral Upper Motor Neuron Flashcards
To get significant dysarthria in the UMN system, you need bilateral damage
In some cases, can you can have dysarthria with unilateral UMN damage?
Yes
Is UUMN dysarthria well studied?
No, but it is a very common problem
It may be the most commonly occurring dysarthria.
Are the characteristics of UUMN dysarthria consisten among cases?
No, there is considerable variability among cases
UUMN dysarthria often occurs with what 2 things when the lesion occurs in the left hemisphere?
aphasia & apraxia
When the lesion is in the right hemisphere it may co-occur with what? (2)
- cognitive
- other speech deficits (not related to dysarthria) – These other symptoms often overwhelm and mask the dysarthric symptoms
UUMN dysarthria tends to be (mild or severe) and of (short or long) duration:
mild and short duration
Why hasn’t UUMN dysarthria been given much attention?
Bc it is mild and short in duration and its being masked by the other concomitant problems
What is UUMN dysarthria usually caused by?
a stroke
Do all lesion causing UUMN damage show up on neurologic scans?
some may be too small to show up
What is the person’s most apparent symptoms of neurologic problems?
UUMN dysarthria, so it can be important for diagnostic reasons
UUMN dysarthria primarily affects
articulation
Speech problems with UUMN dysarthria are due mainly to:
- Weakness of the face and tongue
- Also there may be some spasticity and incoordination
UMN system:
- Includes both direct and indirect pathways
- It is bilateral, one half starts in the left hemisphere and the other half in the right hemisphere
2 tracts of the direct activation pathway:
- corticobulbar tract and corticospinal tract
Corticobulbar goes to:
cranial nerves
corticospinal tracts goes to:
spinal nerves
Most of the innervation is to the
contralateral side
Fibers from the 2 tracts start at the __1___ and then descends via the ___2___ then go into the ___3___ near the level of the _____ and _____.
1 cortex
2 corona radiate
3 internal capsule
4 basal ganglia and thalamus
After fiber tracts descend through the internal capsule and go into the basal ganglia and thalamus, the tracts then descends to the ______.
1 brain stem
At the level of the brainstem, the corticobulbar fibers …
cross to the opposite side just before they get to the level of the cranial nerve they are going to innervate.
At the level of the brainstem, the corticospinal fibers…
cross over or decussate in the pyramids of the medulla
The nerve impulses from the 2 tracts provide:
innervation for finely coordinated, skilled movements
The indirect pathway has the same or different origin and contralateral destinations as the 2 tracts of the direct activation pathway
Same
*It crosses over in the same general area as the direct activation pathway, but not through the pyramids
Why is it called indirect activation pathway?
because it makes synaptic connections with several other structures, such as basal ganglia, cerebellum, reticular formation and other brainstem nuclei
What is the indirect pathway important for?
For regulating reflexes and controlling posture and tone upon which skilled movements must be superimposed
The bulbar speech muscles have mostly bilateral or unilateral innervation?
Mostly bilateral, except for the lower face and part of tongue.
The areas with unilateral innervation have primarily contralateral innervation. One lesion can cause:
more damage
Which nerves have more bilateral innervation (4)? Why?
The Vth, and the part of the VII that goes to upper face
Xth and IXth
- To protect vegetative functions of breathing and feeding
Clinical Characteristics of UUMN dysarthria:
Page 257, Box 9-1.
*Note that all features noted in the table are contralateral to the side of the lesion.
In UUMN lesions:
- usually a combination of direct and indirect pathway lesions
- Typically, weakness and spasticity are seen in the limbs that are affected
- A Babinski reflex is seen on the side of the body affected
- The symptoms often change over time
- Decerebrate posturing
The term “central” facial weakness refers to:
weakness caused by central nervous system damage not peripheral nervous system damage
It involves the lower part of the face.
Symptoms of UUMN dysarthria over time:
Initially weakness, hyporeflexia and hypotonia are seen in limbs
This changes to spasticity, hyperactive reflexes as time goes by
Decerebrate posturing =
Assuming a stiff, rigid posture – it occurs primarily when the cerebrum is removed
Etiologies of UUMN dysarthria:
*Anything that damages the UMN system unilaterally.
- Some trauma and tumors can cause unilateral damage.
- Stroke
Do Degenerative diseases, inflammatory diseases, and toxic-metabolic diseases usually produce unilateral damage?
No.
usually more than unilateral damage so don’t usually cause UUMN
What is the #1 cause of UUMN dysarthria?
Stroke is the most common cause of UUMN dysarthria
What are the types of strokes that may be involved in UUMN damage (4):
- Left carotid or left middle cerebral artery blockages
- Right carotid or right middle cerebral artery blockages
- Unilateral strokes in the posterior cerebral basilar and anterior cerebral arteries
- Lacunar infarcts
Left carotid or left middle cerebral artery blockages:
– these lead to aphasia and apraxia of speech as well as UUMN damage
Right carotid or right middle cerebral artery blockages:
– these lead to neglect and cognitive problems
Unilateral strokes in the posterior cerebral basilar and anterior cerebral arteries:
– also may cause UUMN damage
Lacunar infarcts
- Most common cuase of UUMN dysarthria when dysarthria is the only sign of a stroke
- small strokes-called lacunar because they leave little holes/cavities
- Lacunar infaracts cause UUMN damage in structures like the basal ganglia
- Lacunar infarcts don’t typically lead to aphasia
- Motor or sensorimotor deficits are the most common problems in addition to dysarthria
Percent Site of lesion for same patients in table. These were patients seen by Duffy:
• 95% were supratentorial
- 61% were left hemisphere lesions
- 34% were right hemisphere lesions
What conclusions can be drawn from Duffy’s table about sites of legions?
- Maybe more left than right lesions were referred to Duffy because of aphasia and speech problems, so this may not reflect a true picture
- But enough evidence is available to know that UUMN dysarthria can result from lesions in both left and right hemispheres
Severity of UUMN dysarthria:
- Most are reported to be mild or mild to moderate.
- However, there are some cases reported for moderate to severe UUMN dysarthria.
- UUMN dysarthria is usually transient.
- However,UUMN dysarthria can persist in some cases.
Patient complaints with UUMN dysarthria (6):
1 Patient is usually aware of problem
2 c/o thick tongue or thick, slurred speech
3 speech deteriorates with fatigue (not as sharply as with MG)
4 words don’t come out right-difficulty with pronunciation
5 drooling or mild dysphagia
6 occasionally some have inappropriate crying and laughing
Nonspeech Clinical findings with UUMN dysarthria (2):
- Often have hemiplegia or hemiparesis
* May have sensory deficits
Oral mechanism findings with UUMN dysarthria (5):
page 261, Table 9-3
1 Unilateral lower facial weakness (“central”weakness) in both rest and movement – presence of this is good indicator of dysarthria for stroke patients.
2 Unilateral tongue weakness – usually occurs with facial weakness – presence of tongue weakness is good indicator of presence of dysarthria and dysphagia with stroke patients. Tongue weakness detected best by deviation to weak side upon protrusion.
3 Jaw usually demonstrates normal strength but some contralateral jaw weakness may occasionally be seen.
4 Unilateral palatal weakness
5 Dysphagia may occur
Clinical Speech findings with UUMN dysarthria (10):
- Imprecise consonants is the most common
- Slow rate
- Irregular AMRs (usually mild)– not sure why this occurs as it is symptomatic of cerebellar problems. Could be due to damage to cerebellocortical fibers intermingling with UMN fibers.
- slow AMRs
- hoarseness/harshness
- hypernasality is rare but occasionally occurs
- may sound similar to spastic dysarthria due to damage to indirect activation pathway
- reduced loudness
- intelligibility usually only mildly affected
- therapy often not needed due to recovery
Distinctive characteristics of UUMN dysarthria (8):
• There are no single clear distinguishing features
• Look for a cluster or group of characteristics
o Unilateral central face & tongue weakness
o Primarily results from strokes
o Mild to moderate articulation problems
o Mild irregular articulatory breakdowns
o Slow rate
o Slow & irregular AMRs
o Strained, hoarse voice quality
o Reduced loudness
Main characterisitcs of DAP (pyramidal tract) damage:
- hemiplegia or hemiparesis
- loss / impairments of fine, skilled movements
- absent abdominal reflex
(look at table for more)
Main characteristics of IAP damage:
- increased muscle tone
- spasticity
(look at table for more)
UUMN dysarthria main etiology:
strokes
