26 - Lesions II Flashcards
Background information… What long ascending or descending tracts or other pathways could be involved in brainstem lesions? (6)
1 - Corticospinal tract 2 - Corticonuclear (corticobulbar) tract 3 - Spinothalamic tract 4 - Medial lemniscus 5 - Spinal tract of V 6 - Superior cerebellar peduncle (carries cerebellothalamic fibers) and inferior cerebellar peduncle
Where does the spinothalamic tract run?
Tends to maintain its lateral position as it ascends through the brainstem
Where does the medial lemniscus run?
Tends to shift position from medial to lateral as it ascends through the brainstem
Where does the spinal tract of V run?
Descends ipsilaterally from the mid-pons to C2 of the spinal cord
What fibers does the superior cerebellar peduncle carry?
Cerebellothalamic fibers
What are the two types of structures that could be affected by a brainstem lesion?
Tracts and cranial nerves
Which tracts may be involved in a MEDIAL brainstem lesion (since they are located close to the midline)?
- Pyramidal tract (contains corticospinal tract axons)
- Medial lemniscus (nucleus gracilis and nucleus cuneatus, impairment of vibratory and touch-pressure sense)
Which MEDIAL cranial nerves could be affected by a medial brainstem lesion?
- Oculomotor (CN III)
- Abducent (CN VI)
- Hypoglossal (CN XII)
What information can we gain from determining which of the medial brainstem cranial nerves is affected?
We can determine the LEVEL of the lesion…
What level is CN III located at?
Oculomotor (CN III) - located in rostral midbrain
What level is CN VI located at?
Abducent (CN VI) - located in caudal pons
What level is CN XII located at?
Hypoglossal (CN XII) - located in medulla
Which tracts may be involved in a LATERAL brainstem lesion (since they are located laterally)?
- Spinothalamic tract
- Spinal tract of V
What is the spinothalamic tract responsible for?
Pain and temperature
Some crude/light touch
What is the spinal tract of V responsible for?
Pain and temperature
Note that it descends IPSILATERALLY***
Which LATERAL cranial nerves could be affected by a lateral brainstem lesion?
- Trigeminal (CN V)
- Facial (CN VII)
- Vestibulocochlear (CN VIII)
- Glossopharyngeal (CN IX)
- Vagus (CN X)
What information can we gain from determining which of the lateral brainstem cranial nerves is affected?
We can determine the LEVEL of the lesion…
What level are CN V and CN VII located at?
Trigeminal (CN V) and Facial (CN VII) - located in the pons
What level is CN VIII located at?
Vestibulocochlear (CN VIII) - located in pons/medulla
What level are CN IX and CN X located at?
Glossopharyngeal (CN IX) and Vagus (CN X) - located in the medulla
What is the most common way to determine the location of a brainstem lesion?
The level of the brainstem lesion is most often localized by the cranial nerve involved
What are the two different lesions that can occur in the medial pontine basis?
- Dysarthria hemiparesis (pure motor hemiparesis) syndrome
- Ataxic hemiparesis syndrome
What causes dysarthria hemiparesis (pure motor hemiparesis) syndrome?
Occlusion of the basilar artery - PARAMEDIAN BRANCHES
These branches supply the ventral territory of the pons
What structures are affected in dysarthria hemiparesis (pure motor hemiparesis) syndrome?
- Corticonuclear (corticobulbar) tract
- Corticospinal tract
Describe the deficits that occur with damage to the corticonuclear tract
- These are UMNs, so the deficit would be contralateral weakness on the contralateral side
- Dysarthria will occur
Dysarthria
A motor speech disorder due to weakness or paralysis of the mouth (lips, tongue) and lower half of the face
Describe the deficits that occur with damage to the corticospinal tract
Remember these are UMNs, so the deficits would be contralateral weakness on the upper and lower limb - hemiparesis
What is the other lesion that can occur in the medial pontine basis?
Ataxic hemiparesis syndrome
What causes ataxic hemiparesis syndrome?
Occlusion of the basilar artery - PARAMEDIAN branches which supply the ventral territory of the pons
What three structures are affected?
1 - Corticonuclear (corticobulbar) tract
2 - Corticospinal tract
3 - Pontine nuclei and pontocerebellar fibers
Describe the deficits that occur with damage to the corticonuclear (corticobulbar) tract
These are UMNs, so the deficit will be contralateral lower face weakness and dysarthria (motor speech disorder from muscle weakness)
Describe the deficits that occur with damage to the corticospinal tract
These are UMNs, so the deficit will be contralateral upper and lower limb weakness (motor hemiparesis)
Describe the deficits that occur with damage to the pontine nuclei and pontocerebellar fibers
Contralateral ataxia
Ataxia is disordered movement - a neurological sign consisting of lack of voluntary coordination of muscle movements that includes gait abnormality.
What is Foville’s syndrome?
A syndrome caused by a lesion in the medial pontine basis and tegmentum
What causes Foville’s syndrome?
Occlusion of the basilar artery - PARAMEDIAN branches which supply the ventral and dorsal territories of the pons
What three structures are affected by Foville’s syndrome?
1 - Corticonuclear (corticobulbar) tract
2 - Corticospinal tract
3 - Facial colliculus
Describe the deficits that occur by damage to the corticonuclear (corticobulbar) tract
Contralateral lower face weakness and dysarthria
What is dysarthria?
A speech deficit arising from weak facial muscles and tongue
What deficits occur by damage to the corticospinal tract?
Contralateral upper and lower limb weakness
Does the facial colliculus contain UMNs or LMNs?
LMN
What two structures in the facial colliculus are affected by Foville’s syndrome?
- Abducens nucleus or paramedian pontine reticular formation (PPRF)
- Facial nerve root fascicles
What deficits occur by damage to the abducens nucleus or paramedian pontine reticular formation (PPRF)?
IPSILATERAL horizontal (lateral) gazy paralysis/palsy
On the side of the lesion, the eye cannot move horizontally in the lateral direction - can’t look out
What deficits occur by damage to the facial nerve root fascicles?
IPSILATERAL face paralysis
What is Pontine Wrong-Way Eye syndrome?
A syndrome caused by a medial pontine basis and tegmentum lesion
Occlusion of which vessel causes Pontine Wrong-Way Eye syndrome?
Occlusion of the basilar artery - PARAMEDIAN branches that supply the ventral and dorsal territories of the pons
What three structures are affected by Pontine Wrong-Way Eye syndrome?
1 - Corticonuclear (corticobulbar) tract
2 - Corticospinal tract
3 - Abducens nucleus or paramedian pontine reticular formation (PPRF)
What is the result of a damaged corticonuclear tract?
Contralateral lower face weakness and dysarthria
What is the result of a damaged corticospinal tract
Contralateral upper and lower limb weakness
What is the result of a damaged abducens nucleus or paramedian pontine reticular formation (PPRF)?
Ipsilateral lateral gaze paralysis/palsy
What is Millard-Gubler Syndrome?
A syndrome caused by a lesion to the medial pontine basis and tegmentum
What causes Millard-Gubler syndrome?
Occlusion of the basilar artery - PARAMEDIAN branches which supply the ventral and dorsal territories of the pons
Which three structures are affected in MIllard-Gubler syndrome?
1 - Corticonuclear (corticobulbar) tract
2 - Corticospinal tract
3 - Facial nerve fascicles
What deficits occur by damage to the corticonuclear (corticobulbar) tract?
Contralateral lower face weakness and dysarthria
What deficits occur by damage to the corticospinal tract?
Contralateral upper and lower limb weakness
Does the facial nerve fascicle contain UMNs or LMNs?
LMNs
What deficits occur by damage to the facial nerve fascicles?
IPSILATERAL facial weakness
What other regions of the pons can be involved with a lesion caused by occlusion of the basilar artery - paramedian branches supplying the ventral and dorsal territories of the pons?
- Medial lemniscus
- Medial longitudinal fasiculus (MLF)
What deficits occur with damage to the medial lemniscus?
Contralateral decreased proprioception, vibratory sense and tactile discrimination
What deficits occur with damage to the medial longitudinal fasiculus (MLF)?
Internuclear ophthalmoplegia (INO)
Internuclear ophthalmoplegia (INO)
A specific gaze abnormality characterized by impaired horizontal eye movements with weak adduction of the affected eye
Further, there is abduction nystagmus (involuntary, jerky eye movements) of the contralateral eye
The result is diplopia and decreased vision
There is one syndrome that occurs by a lesion in the lateral caudal pons. What is it named and what vessel occlusion causes it?
AICA syndrome caused by occlusion of the anterior inferior cerebellar artery (AICA)
Which five structures are affected by AICA syndrome?
1 - Middle cerebellar peduncle 2 - Vestibular nuclei 3 - Trigeminal nucleus and tract 4 - Spinothalamic tract 5 - Descending sympathetic fibers
What is the deficit that results from damage to the middle cerebral peduncle?
Ipsilateral ataxia
What is the deficit that results from damage to the vestibular nuclei?
Vertigo and nystagmus
What is the deficit that results from damage to the trigeminal nucleus and tract?
Ipsilateral decreased pain and thermal sensation in the face
What is the deficit that results from damage to the spinothalamic tract?
Contralateral decreased pain and thermal sensation in the body
What is the deficit that results from damage to the descending sympathetic fibers?
Ipsilateral Horner’s syndrome
Horner’s syndrome
A combination of symptoms that arises when a group of nerves known as the sympathetic trunk is damaged.
The signs and symptoms occur on the same side as the lesion of the sympathetic trunk.
It is characterized by:
- Miosis (a constricted pupil)
- Ptosis (a weak, droopy eyelid)
- Aapparent enophthalmus (inset eyeball)
- Anhidrosis (decreased sweating)
There is one syndrome that occurs with a lesion in the dorsolateral rostral pons. What is it called and what vessel is occluded?
Superior cerebellar artery syndrome
The superior cerebellar artery is occluded
What structure is affected by Superior Cerebellar Artery syndrome?
Superior cerebellar peduncle and cerebellum
What is the result of damage to the superior cerebellar peduncle and cerebellum?
Ipsilateral ataxia of cerebellar origin
Ataxia is a lack of voluntary coordination of muscle movements
There is one syndrome that results from a lesion in the medial medulla. What is it called?
Medial medullary syndrome
What two vessel occlusions can cause medial medullary syndrome?
- Anterior spinal artery - paramedian branches
- Vertebral artery - paramedian branches
What three structures are affected due to medial medullary syndrome?
1 - Corticospinal tract
2 - Hypoglossal nerve and nucleus
3 - Medial lemniscus
What is the result of damage to the corticospinal tract?
Weakness on the contralateral upper and lower limb
AKA contralateral hemiparesis
What type of neurons do we find in the hypoglossal nerve and nucleus?
LMNs
What is the result of damage to the hypoglossal nerve and nucleus?
- Weakness/paralysis of the ipsilateral tongue
- Atrophy of the ipsilateral tongue muscles
What is the result of damage to the medial lemniscus?
Contralateral decreased vibratory and proprioceptive sensation and discriminatory (fine) touch sensation
There is one syndrome that results from a lesion in the lateral medulla. What is it called?
Lateral medullary syndrome (Wallenberg’s syndrome)
What vessel occlusions can cause lateral medullary syndrome?
AKA Wallenberg’s syndrome
Vertebral artery thrombosis is the most common cause
PICA thrombosis is a less common, but still possible cause
What seven structures are affected by lateral medullary syndrome?
1 - Inferior cerebellar peduncle 2 - Vestibular nuclei 3 - Spinothalamic tract 4 - Spinal tract and nucleus of V 5 - Descending sympathetic fibers 6 - Nucleus ambiguus 7 0 Nucleus solaritus
What is the inferior cerebellar peduncle responsible for?
Brings proprioception from spinal cord and medulla (for body and head, respectively)
What is the result of damage to the inferior cerebellar peduncle?
Ipsilateral ataxia
Ataxia is a lack of voluntary coordination of muscle movements
What is the result of damage to the vestibular nuclei?
- Unsteady gait
- Vertigo
- Horizontal or rotatory nystagmus
- Nausea
- Vomiting
What is the result of damage to the spinothalamic tract?
Decrease or loss of pain and thermal sense from the contralateral side of the body
What is the result of damage to the spinal tract and nucleus of CN V?
Decrease or loss of pain and thermal sense from the ipsilateral face
What is the result of damage to the descending sympathetic fibers?
Ipsilateral Horner’s syndrome
Horner’s syndrome
- Ptosis of the upper eye lid
- Miosis (constriction of the pupil)
- Anhidrosis (loss of sweating in the face)
What is the function of the nucleus ambiguus in the medulla?
Innervates the laryngeal and pharyngeal muscles
What is the result of damage to the nucleus ambiguus in the medulla?
- Dysphonia
- Dysphagia
- Ipsilateral decrease of gag reflex
Dysphonia
Hoarsness due to ipsilateral vocal cord paralysis
Dysphagia
Difficulty swallowing
What is responsible for the gag reflex?
Vagus
What is the result of damage to the nucleus solitarius in the medulla?
Decrease in taste sensation in the ipsilateral tongue
Which cranial nerves are involved in the nucleus solitarius?
VII, IX, X
What is the other debilitating affect of lateral medullary syndrome (Wallenberg’s syndrome)?
Loss of vertical orientation
What does it mean to have a loss of vertical orientation?
The individual perceives the world as it is upside down or turned sideways
What is alternating hemipalegia?
Alternating hemiplegia refers to a form of hemiplegia that has an ipsilateral and contralateral presentation in different parts of the body.
The damage occurs in lesion seen close to the midline of the brainstem.
The damage leads to ipsilateral cranial nerve deficits and contralateral long tract deficits.
Which long tracts are affected in alternating hemipalegia?
Pyramidal tract
Medial lemniscus
Which cranial nerves are affected in alternating hemiplegia?
CN III, VI, XII
How else can we describe the alternating hemiplegia more specifically? What does this depend on?
We can divide it into upper, middle and lower alternating hemiplegia syndromes based on the level of the cranial nerve involved.
Remember the rule of 4s… CN III is located the most superior and is therefore upper, CN VI is next and is therefore middle, and CN XII is the most inferior and is therefore lower alternating hemiplegia.
