Lecture 24: Brainstem 3: Syndromes Flashcards
What do patients with cranial nerve present with?
i. double vision (horizontal or vertical)
ii. Hemi-facial numbness
iii. Complete hemi-facial weakness
iv. vertigo (sensation of room spinning…vestibular nuclei)
v. difficulty swallowing
What do patients with cerebellar dysfunction present with?
i. coordination/balance difficulties out of proportion to their weakness or numbness
When should you consider a brainstem function?
i. Patients has BOTH cranial nerve deficit and cerebellar deficit
ii. There is a crossed hemiparesis (weakness on opposite side of CN palsy and ataxia)
iii. multiple cranial nerves are involved AND there are no crossed motor/sensory signs in extremities
What is a key feature to remember about the brainstem?
Brainstem is a highway, not a destination
It is also the home of most of the cranial nerve nuclei
What is the 4-4-4 rule of the brainstem?
4 cranial nerves in medulla = 9-12
-swallowing, movement of the tongue
4 cranial nerves in pons = 5-8
-double vision, facial weakness, facial sensory loss, vertigo
4 bumps in midbrain (lmao)
-two cranial nerves, 3 and 4, do some shit in the eye
-superior colliculus: level at which third nerve leaves
-inferior colliculus: level at which fourth nerve leaves
Within a region of the brainstem, how is brainstem structure localized?
Ventral-dorsal
Medial to lateral
What is significance of ventral-dorsal localization in brainstem?
ventral = motor tract Middle = ascending sensory tracts (except in medulla where dorsal columns are still in back) Dorsal = fibers to cerebellum and most of cranial nerve nuclei (even though their axons could leave ventrally, like motor axons
What is significance of medial-lateral localization?
- motor tract axons leave medially as is the medial lemniscus (in pons and midbrain)
- motor nuclei is here as well
- periphery, we have the anterolateral system (spinothalamic) and descending first-order sympathetic neurons…also mixed nerves leave laterally
What are the three artery types in the braintem?
- Paramedian (basilar penetrating) arteries that come off the undersurface of the basilar artery (middle front of brainstem)
- Short circumferential arteries = supplies lateral brainstem
- Long circumferential arteries = supplies dorsal brainstem and the cerebellum
i. PICA (posterior inferior cerebellum)
ii. AICA (anterior inferior cerebellum)
iii. Super cerebellar artery (top of midbrain and cerebellum)
What is Internuclear Opthalmoplegia (INO)?
a unilateral or bilateral lesion to MLF
-the lesion of MLF is on the same side (ipsilateral) to the eye that cannot move towards the nose
-usually demyelination in a young person or when bilateral
-usually infarction in an older person (usually unilateral)
Remember, MLF = tract of axons!!
What is most likely cause of bilateral INO?
Demyelination (MS)
What are possible etiologies for brainstem dysfunction?
i. vascular lesions
ii. inflammation/demyelination (MS)
iii. Tumors
intra-axial
extra-axial
iv. Metabolic disorders (Wernicke’s disease)
v. herniation
What is your diagnosis when you have a CN lesion on the right and a CN lesion on the left?
Subarachnoid space, or something that is outside of brainstem
What is your diagnosis when you have multiple CN deficits on the same side and loss of hearing?
Something Extra-axial
What are types of etiology of Horner’s Syndrome?
- Central (first-order neuron lesion)
- associated with lateral medullary stroke
- Pre-ganglionic (second order neuron lesion)
- commonly caused by an apical lung tumor
- Postganglionic (third order neuron lesion)
- commonly caused by carotid disease (dissection, thrombosis), vascular headaches or cavernous sinus lesion
