DIT review - Neurology 3 Flashcards
What is the cause and presentation of central pontine myelinolysis
- Due to rapid correction of hyponatremia leading to massive axonal demyelination in pontine white matter
- MRI will show increased signal intensity in the pons
- Presentation:
- Acute paralysis, dysarthria (difficulty speaking), dysphagia (difficulty swallowing), diplopia (double vision), loss of consciousness
- Can cause “locked in syndrome” – preserved consciousness with paralysis except for eye movement
What will be seen in a CN V motor lesion
- Jaw deviates towards side of lesion
What will be seen in CN X lesion
- Uvula deviates away from side of lesion
What will be seen in CN XI lesion
- Weakness turning head contralateral to lesion (SCM)
- Shoulder droop on side of lesion (trapezius)
What will be seen in CN XII lesion?
- Tongue deviates toward side of lesion (“lick your wounds”)
Describe the difference between an UMN and LMN lesion of the facial nerve
- Upper motor neuron lesion - more severe, could mean stroke
- Destruction of motor cortex or connection between motor cortex and facial nucleus
- Contralateral paralysis of lower facial muscles (sparing of forehead)
- Lower motor neuron lesion - Bell’s Palsy
- Destruction of facial nucleus or facial nerve
- Ipsilateral paralysis of upper and lower muscles of face
- Explanation:
- Facial motor nucleus receives motor fibers for the lower face from the opposite motor cortex and motor fivers for the upper face from both moto cortices
- So if a lesion occurs in the L motor cortex facial region, there is still sufficient innervation for R upper face from R motor cortex
- But since L motor cortex is the only innervation of R lower face, there will be paralysis of R lower face
What are the 4 midline structures and associated lesion presentations in the midbrain
Motor pathway - contralateral weakness
Medial lemniscus - contralateral proprioception/vibration deficit
Medial longitidinal fasciculus - ipsilateral internuclear ophthalmoplegia
Motor nuclues and nerve - ipsilateral CN motor loss (3, 4, 6, 12)
What are the 4 lateral structures and associated lesion presentations of the brainstem?
Spinocerebellar - ipsilateral ataxia
Spinothalamic - contralateral pain and temp
Sensory V - ipsilateral pain and temp of the face
Sympathetic - ipsilateral Horner’s
Describe the blood supply of the brainstem (medial and lateral of midbrain, pons, and medulla)
- Midbrain:
- Medial - posterior cerebral
- Lateral - posterior cerebral
- Pons:
- Medial - Basilar
- Lateral - Anterior inferior cerebellar artery (AICA)
- Medullar:
- Medial - anterior spinal (ASA)
- Lateral - Posterior inferior cerebellar artery (PICA)
What will you see if you have a lesion of the left medial longitudinal fasciculus (MLF)?
You will have no problem when looking L, but when looking R, the L eye will not move medially (problem of the L medial rectus muscle)
What is the other term for lesion of the MLF?
Internuclear ophthalmoplegia
What is the cause and presentation of Weber syndrome?
- Lesion of medial midbrain
- Caused by posterior cerebral artery
- Presentation:
- Contralateral spastic paralysis or hemiparesis
- CN III palsy (eye turned down and out)
- Ptosis (CN III)
What is the cause and presentation of Wallenberg syndrome
- Lesion of lateral medulla
- Caused by posterior inferior cerebellar artery (PICA)
- Presentation:
- Dysphagia, hoarseness, decreased gag reflex (CN IX and X)
- Ipsilateral loss of pain and temp of the face
- Contralateral loss of pain and temp of the body
- Ipsilateral Horner syndrome
- Ipsilateral cerebellar defects
- Vertigo, nystagmus, nausea, vomiting (CN VIII since defect is upper medulla)
Lesion of what artery can cause locked-in syndrome
This is a lesion of the medial pons – basilar artery
What will you see on spinal tap in a subarachnoid hemorrhage
Bloody or yellow (xanthochromic) tap
Yellow = breakdown of hemoglobin from blood into bilirubin
What are the layers that you go through during a spinal tap?
Skin - superficial fascia - supraspinous ligament - interspinous ligament - ligamentum flavum - epidural space - dura mater - subdural space - arachnoid membrane - subarachnoid space (this is where CSF is)
Describe the flow of CSF
- Ependymal cells of choroid plexus make CSF - lateral ventricles - foramine of Monro - 3rd ventricle - cerebral aqueduct - 4th ventricle - foramine of Luscka + foramine of Magendie - subarachiod space - reabsorption via arachnoid granules - dural venous sinuses
Describe defining features of glioblastoma multiforme
- Malignant tumor of astrocytes à GFAP (+)
- Found in cerebral hemispheres and may cross corpus callosum – “butterfly lesion”
- Pseudopalisading – tumor surrounding central necrosis
- Poor prognosis
Describe defining features of oligodendroglioma
- Most often in frontal love
- “Fried egg” appearance (round nuclei with clear cytoplasm)
Describe defining features of pilocytic astrocytoma
- Benign tumor of astrocytes à GFAP (+)
- Usually arises in posterior fossa
- Cystic lesion with mural nodule
- Rosenthal fibers – eosinophilic corkscrew fibers
Describe defining features of medulloblastoma
- Malignant tumor derived from neuroectodem
- Can compress 4th ventricle leading to hydrocephalus
- Homer Wright rosettes (small blue cells wrap around pink areas of neuritic processes)
Describe defining features of ependymoma
- Malignant tumor of ependymal cells (most often in 4th ventricle)
- Can compress 4th ventricle leading to hydrocephalus
- Perivascular pseudorosettes (tumor cells surrounding vessel)
