What is the name of the structure where anterolateral system axons (pain, temperature) cross the spinal cord?
The white comissure.
Where do axons of proprioception / mechanoreception (touch, vibration, pressure) cross the midline?
The lower medulla.
Is sympathetic innervation ipsilateral, contralateral, or a mix?
What's the most common sympathetic syndrome? How can you test for it?
Horner's Syndrome. Dripping cocaine in the eye should make pupil dilated - if it doesn't, sympathetics are lesioned.
In what spinal segments do nerves controling bladder enter/exit ?
What is an infantile bladder? What stops us from having an infantile bladder? Lesions in what location will cause it?
Bladder fills until stretch receptors detect fullness, then it reflexively empties. Cortical descending fibers inhibit this reflex. Lesions above pons cause it.
What effect do lesions between the pontomesencephalic micturation center and the conus medullaris have on the bladder? (note acute vs. chronic effects) Why?
Acutely: acontractile bladder -> urinary retention
Chronically: spastic bladder due to loss of ihibitory signals to the detrusor
What effects do lesions of the cauda equina and conus medullaris have on the bladder? Why?
Atonic (flaccid) bladder -> urine just dribbles out. Loss of motor innervation to detrusor and sphincters. Loss of sensation.
What major arteries supply the spinal cord? What is their contribution to total blood supply?
One anterior spinal artery (anterior 2/3) and two posterior spinal arteries (posterior 1/3).
What artery supplying the spinal cord is most likely to infarct?
The anterior spinal cord.
Slow and stiff muscles. UMN or LMN lesion?
Weak, crampy muscles. LMN or UMN lesion?
Increased tone, hyperactive reflexes, pathological reflexes (eg. Babinski's). UMN or LMN lesion?
Weakness, atrophy, fasciculations, decreased tone, hypoactive lesions. UMN or LMN lesion?
Do you usually get bladder and bowel symptoms from a unilateral lesion?
How do the acute symptoms of complete cord transection vary from the later, chronic features?
Acute: spinal shock with flacid plegia (weakness), numbess, urinary retention, constipation
Chronic: spastic plegia, spastic bladder and rectal sphincter with incontince
(in chronic, things are "disinhibited")
Sparing what spinal segment with allow indepedent transfer (ability to move self)?
What's the main type of information traveling contralaterally in the spinal cord? What does this mean for spinal hemisection (Brown-Sequard Syndrome)?
Pain and temperature. Loss of pain and temperature will be contralateral, all else will be ipsilateral.
In a hemisegmented spinal cord, what will be different at the level of the lesion vs. below it?
At the level of the roots, there can be a LMN damage (producing flaccid, not spastic, weakness/paralysis).
What do central cord lesions affect? Why?
Primarily the crossing fibers of the spinothalamic tract in the white comissure (pain and temperature), because that's where they run. If the lesion is large enoug, it make affect anterior horn cells.
What are some causes of central cord lesions? (3 things)
Syringomyelia (CSF-filled cavity in spinal cord), hematomyelia, intramedullary tumor)
What is Tabes Dorsalis? Symptoms? Common cause?
Destruction of posterior columns. Impaired propriosensation (especially in the dark), impaired mechanoreception, inabiilty to detect bladder fullness, shooting pains while walking. Syphilis.
What's the Romberg test? Why does this happen?
Patient with balance loses balance when eyes are closed. Visual data can compensate for lack of proprioception and be sufficient for balance.
Is a positive Romberg test indicative of a problem with the cerebellum?
No! It doesn't show a problem with the cerebellum. If it were, patient wouldn't have balance with eyes open.
What are Argyl Robinson pupils?
Pupils accomodate but don't react (to light)... like a prostitute... from whom you got syphilis / Tabes Dorsalis.
Hey, I didn't make this up.
What regions of the spinal cord are affected in posterolateral column syndrome?
Dorsal columns and corticospinal tracts.
What's the pathophysiology of posterolateral column syndrome (aka subacture combined degeneration)? Most common cause?
Myelin degeneration without inflammation. B12 deficiency.
What are the signs/symptoms of posterolateral column syndrome?
Combination of tabes dorsalis (sensory loss, positive Romberg sign) and corticospinal tract dysfunction (spasticity, hyperactive reflexes).
What's one notable pathological reflex seen posterolateral column syndrome?
Babinski sign - upgoing toes when bottom of foot stroked (normally they should flex).
What do patients with anterior horn cell disease experience? Is the disease focal or widespread?
Flaccid paralysis and atrophy of affected muscles. Can be either focal or widespread, depending on cause.
What are the main causes of anterior horn disease? (name 3)
Spinal Muscular Atrophy (inherited or aquired)
Infectious (esp. Polio, but others as well)
Benign focal forms (less important)
What is combined anterior horn cell - pyramidal tract syndrome?
Amyotrophic Lateral Sclerosis (ALS)
In anterior spinal artery occlusion, what area of the spinal cord is spared?
Dorsal columns (proprioception, mechanoreception (makes seense)
What is lost in anterior spinal artery occlusion? (4 things)
Below lesion: initial flaccid weakness -> spastic paraparesis
At lesion -> LMN abnormalities
Pain and temperature below lesion.
Bowel / bladder control.
What does it mean for a tumor to be intramedullary? What spinal cord syndrome will it probably mimic?
Within the parenchyma of the spinal cord. Will probably mimic complete cord transection.
How do symptoms of an intradural extramedullary lesion evolve?
Initially -> root compression
Increasing size -> more areas, until complete cord transection
What two tumor types tend to cause intradural extramedullary tumors?
Schwannomas and meningiomas
Contrast the symptoms of extradural tumors from intradural extramedullary tumors. Contrast their appearance on MRI.
Trick question - extradural and intradural extramedullary tumors have essentially the same symptoms. They do appear very distinct on imaging though.
Causes of extradural lesions: list 5.
Disc disease (esp. herniation)
Primary bone tumor
(note 3/5 of list are cancer)
Why are we all going to be stiff and incontinent in our old age?
What is cervical spondylosis?
Chronic degenerative change to bony structuresand ligaments secondary to loss of elasticity in discs and surrounding structures.
Does L5 disc herniation cause a spinal cord syndrome? What do lumbar disc herniations cause?
No! There's no spinal cord at L5. Typically lumbar disc herniations cause LMN lesion, dermatomal sensory loss (making loss/depression of reflexes at the level make sense), and radicular pain.