Neurology Mike-Mehlman Flashcards
Stroke risk factors ?
- HTN=Carotid arteries=Endothelial damage =Atherosclerotic plaque=Carotid stenosis
2.Atrial fibrillation=Turbulence and Stasis =Left atrial mural thrombus
“How do most strokes occur?” à
“Oh, well the patient will usually have c
Circle of willis affect of STROKE ?
- ACA= Motor/sensory abnormalities of LEG
2.MCA=Motor/sensory abnormalities of ARM & FACE
=Dominant MCA stroke—-Wernick & Broca aphasia
=Non dominant MCA stroke — Hemispatial neglect
3.PCA=Contralateral Homonymous Hemianopsia
=Prosopagnosia (inability to recognize faces)
Stroke syndromes?
- Lateral medullary
syndrome
2.Medial medullary
syndrome
3.Lateral pontine
syndrome
4.Weber syndrome
5.Locked-in syndrome
6.Gerstmann
syndrome
7.Hemiballismus
Lateral medullary
syndrome?
Wallenberg syndrome
- Dysphagia=Posterior inferiror cerebral artery /Vertebral artery stroke
- Horner syndrome=Miosis+Ptosis+Anhidrosis
dysphagia + ipsilateral Horner syndrome after a stroke.
Medial medullary
syndrome ?
ipsilateral tongue deviation
=stroke Anterior spinal artery
Lateral pontine
syndrome?
- ipsilateral Bells palsy after a stroke.
- stroke of anterior inferior cerebellar artery (AICA)
Weber syndrome ?
- Midbrain stroke.
- The answer for ipsilateral CN III palsy (i.e., down and out eye) + contralateral
spastic hemiparesis (weakness).
Locked-in syndrome ?
- Basilar artery stroke.
- The answer for inability to move entire body except for eyes
Gerstmann
syndrome ?
- Stroke=Angular gyrus of parietal lobe
- Tetrad
=Agraphia
=Acalculia
=Finger agnosia
=Left right disassociation
Hemiballismus ?
Stroke of subthalamic nucleus
=- Causes “ballistic” flailing of contralateral arm and/or leg.
For example, if they say patient has
random flailing of left arm follow
Lenticulostriate strokes ?
HTN causing lipohyalinosis of these small, penetrating vessels =Small lenticulostriate arteries deep within the brain
The USMLE doesn’t give a fuck about the specific types of lacunar
defic
Charcot-Bouchard
microaneurysms ?
e tiny (<1mm) aneurysms can form within
lenticulostriate arteries that can bleed an cause hemorrhagic strokes /
intraparenchymal (intracerebral) bleeds.
which Necrosis in nervous sytem ?
Liquefactive necrosis
What wiil be seen in Ischemic infraction of the CNS ?
“Red neurons”
=This refers to their strong eosinophilic (pink) staining with H&E.
“Red neurons”
Macrophage of brain ??
Microglia are the resident macrophages of the CNS. They phagocytose necrotic brain/spinal tissue.
Scar formation of CNS which cell ?
Astrocytes are the glial cells (non-neuronal cells of CNS/PNS) that proliferate and become a glial scar
(gliosis).
Wallerian degeneration ?
Wallerian degeneration is a term that refers to degradation of an axon/myelin sheath distal to the site of injury.Both PNS and CNS neurons undergo Wallerian
degeneration
regeneration occurs within the PNS, not CNS. WHY ?
This is because PNS Schwann cells can
regenerate myelin, whereas CNS oligodendrocytes do not effectively regenerate myelin post-injury.
why degeneration
of the optic nerve results in permanent blindness ???
The optic nerve is considered an extension of the CNS and is myelinated by oligodendrocytes; the other
cranial nerves are part of the PNS and are myelinated by Schwann cells. This distinction is why degeneration
of the optic nerve results in permanent blindness, whereas other facial nerves (e.g., CN VII for Bell’s palsy)
have better regenerative potential.
Other vascular DDx causing neuro Sx ?
- Subclavian steal syndrome
- Vertebral artery stenosis
- Vertebral artery dissection
Subclavian steal syndrome ?
Suclavian artery=1st branch=Vertebral artery
Narrow in branch point of vertebral artey =Low pressure in VA =Backflow of blood = DIZZINESS
Blood pressure is different between the two arms.
Subclavian steal syndrome ?
USMLE question pattern
2 pattern ………………….
- they’ll give you dizziness in
someone who has BP different between the arms and then ask for merely
“subclavian steal syndrome,” or “backflow in a vertebral artery” as the
answer
2.they’ll give you BP in one of the arms + give you dizziness,
then the answer will be, “Check blood pressure in other arm.”
- Next best step in Dx is CT or MR angiography
- I should point out that probably ¾ questions on USMLE where blood
pressure is different between the arms, this refers to aortic dissection. But
¼ is subclavian steal syndrome. As per my observation.
Vertebral artery stenosis ?
=Unexplained dizziness
=But no pressure difference in both hands
=ATHEROSCLEROSIS
“Vertebrobasilar insufficiency” is a broader term that refers to patient
“Vertebrobasilar insufficiency” is a broader term that refers to patients
who have either subclavian steal syndrome or vertebral artery stenosis.
Vertebral artery dissection ?
1.False lumen =By dissection of VA =stasis and clot formation =Embolize brain & cause STROKE
VA Dissection DRUG ?
- NBME can mention recent visit to a chiropractor (neck manipulation is
known cause). - The answer on the NBME is [ heparin ] for patients who have experienced
posterior stroke due to vertebral artery dissection. Sounds weird because
it’s arterial, but it’s what USMLE wants. Take it up with them if you think
it’s weird
Aphasia types ??
- Wenicke
- Broca
- Conductive
- Global
- Transcortical sensory
- Transcortical motor
Wernicke Aphasia ??
- Can make word=But meaningLess
- Comprehension Impaired
- Repitition impaired
- Temporal lobe=MCA Infarct
Broca aphasia ?
- Repitation impaired
- Frontal lobe=MCA
- NON-FLUENT Aphasia
patient has “telegraphic speech”), where there is frustration in
not being able to communicate despite comprehending normally, akin to trying to
communicate in a second language.
Conductive aphasia ?
- Patient only has repetition impaired.
- Stroke of arcuate fasciculus, which is bundle of nerve fibers that connects Wernicke
and Broca areas
Broca A = Wernicke A + Arcuate fasciculus
Transcortical
sensory & Motor ?
Transcortical sensory= W A But Repitation intact
Transcortical Motor= Broca A but repitation is intact
Stroke management /Tx ??
1.Non contrast CT = No Blood in Head = Ischemic stroke
2.CT= Blood is present = Hyperdense areas in CT = Hemorrhagic stroke
Ischemic stroke = tPA is given + ASPIRIN
BP should be brought down rapidly until below 185/110 so that tPA can be given. Below
this threshold, cautious/slower BP control should be done, since BP can actually facilitate
perfusion of penumbric areas of ischemia (i.e., areas of ischemia around the stroke).
- The USMLE can be tricky about this point, where they might say a guy awoke this morning
from sleep 2 hours ago + has facial drooping, where tPA is wrong because the stroke could
have occurred at any point while he was asleep + the last time he was observed to have no
stroke signs was the night before
Hemorrhagic stroke Tx ?
- Do not give tPA. First step is lowering BP (labetalol, nicardipine, or hydralazine).
- Reduce BP rapidly to systolic <140 mm Hg.
- Reverse anticoagulation if the patient is on it (i.e., FFP for patients on warfarin).
Sodium correction BAD effects in CNS ?
1.Correction of HYPERNATREMIA with HYpOtonic saline = Cerebral edema
2.Correction of HYPOnatremia with HYPERtonic saline =Central pontine myelinolysis
=Osmotic demyelination
=Locked in syndrome
USMLE can show MRI of the pons similar to the above.
Mike NOTE
Hypercalcemic crisis Tx ?
Hypercalcemia =Cognitive dysfunction & Delirium
Also Na disturbance can cause = Hypercalcemia
Tx= Normal Saline + Bisphosphonate Therapy = PAMIDRONATE
Pseudotumor cerebri ?
1.inc ICP
2.Some notable causes are obesity (idiopathic intracranial hypertension), OCPs, isotretinoin, and danazol.
Reye syndrome ?
After aspirin administration = Cerebral edema + Hepatotoxicity
Diffuse Axonal Injury ?
USMLE can show MRI showing scattered hyperintense (white) lesions
Deceleration injury (e.g., car accident) followed by severe cognitive and/or motor/sensory dysfunction
(i.e., following an MVA, the patient has to relearn tying his/her shoes, etc.).
Spinal tract function ?
- Spinothalamic tract
- Corticospinal tract
- Dorsal porterior colums
Spinothalamic tract ?
1.Pain and temperature sensation from contralateral body.
2.Decussation point is called anterior white commissure. A lesion at this point is called syringomyelia, where there is bilateral loss of pain and temperature below
the lesion.
Cross-over (decussation) point is in spinal cord, meaning if, e.g., the left spinothalamic tract in the spinal cord is fucked up, we lose pain and temperature
on the right side of the body below the lesion.
Corticospinal tract >?
- Motor function from ipsilateral body.
- In other words, if left-sided corticospinal tract is fucked up, we lose motor
function on the left side below the lesion
Dorsal columns ?
- Carry vibration + proprioception from ipsilateral body.
- Tabes dorsalis is dorsal column lesion caused by neurosyphilis.
- If the dorsal columns are disrupted, patient will have (+) Romberg test, which is
where he/she falls over when standing with eyes closed. I discuss this more below
UMN
Present as hyperreflexia, hypertonia, clonus, Babinski sign
Lesion of the corticospinal tract (i.e., lesion from the cerebral cortex down until the anterior horn in the spinal cord)
LMN ?
- Present as hyporeflexia, hypotonia/flaccidity, fasciculations
Lesion involving the motor neuron from the anterior horn until the muscle itself. If the USMLE
gives you an anterior horn lesion, this will be LMN, not UMN.
Tabes dorsalis ?
1.NeuroSyphilis - Loss of dorsal Columns
2.Bilateral = Loss of Vibration & Proprioception \
3.Ataxia with (+) Romberg test à indicates dorsal columns are fucked up as
the cause of the ataxia, since proprioception is lost. In contrast, if the cause of
ataxia is cerebellar, for instance, Romberg test is (-).
Findings in Picture- Myelin stain used, where normal myelination appears black. The dorsal
columns are fucked up here, which is why they’re white
Syringomyelia ??
9/10 Qs will give bilateral loss of pain and temperature due to lesion of
anterior white commissure (decussation point for spinothalamic tract).
Brown-Sequard syndrome ?
- Ipsilateral loss of vibration + proprioception (dorsal columns)
- Ipsilateral loss of motor function (corticospinal tract).
- Contralateral loss of pain + temperature (spinothalamic)
viral infection or SLE causing transverse myelitis.
Transverse myelitis ?
1.Inflammation of spinal cord
2. USMLE likes viral infection and SLE (autoimmune)
3. Brown-Sequard syndrome is one way transverse myelitis presents
Central cord syndrome ?
- The answer when weakness in the upper limbs is greater than weakness in the lower limbs.
- Typically follows hyperextension injury of the neck during whiplash in a rearend MVA.
Anterior cord syndrome ?
- The answer when there’s preservation of vibration/proprioception but loss
of motor + pain/temperature, classically in patient with arterial disease. - In other words, everything but the dorsal columns is fucked up. Essentially
the opposite of tabes dorsalis.
Brachial plexuas injuries ?
- Klumpke
- Erb Duchenne
Klumpke ?
Lower brachial plexus
- Lower brachial plexus injury (C8-T1).
- Sometimes rather than Klumpke written as the diagnosis, the answer will just be
“lower brachial plexus” when they ask for what’s injured.
Claw-Hand
Erb Duchenne ?
- Upper brachial plexus injury (C5-C6).
- Sometimes rather than Erb-Duchenne written as the diagnosis, the answer will
just be “upper brachial plexus” when they ask for what’s injured.
-Arm is adducted, pronated, and wrist flexed.
-Waiters Tip deformity
Neural tube defects =Spina bifida when occured ?”
3-4 weeks gestation
Spina bifida types ?
- SB Occulta= Vertebral body -Open posteriorly
- Meningocele = Herniation of just meninges
- Meningomyelocele=Herniation of both meninges & spinal cord
Spina bifida causes ?
- The pregnant woman needs adequate folic acid (vitamin B9) prior to and during early pregnancy for
prevention. - Antiepileptics (i.e., particularly valproic acid, but also phenytoin and carbamazepine) are also associated
with neural tube defects. - Neural tube defects lead to increased AFP and acetylcholinesterase in CSF.
Spinal conditions defects ?
Onekgulaaaaaaaaaaaaaaaaaaaa
- Cervical spondylosis
- Atlantoaxial subluxation
- Lumber spinal stenosis
- Cervical foraminal stenosis
- Spondylolisthesis
- Disc herniation
- Lumbosacral strain
- Sciatica
- Meralgia paresthetica
- Conus medullaris
- Cauda equina
- Tethered cord
- Scoliosis
- Kyphosis
- Lordosis
Cervical spondylosis ?
Degeneration of pars interarticularis component of
vertebral body.
The answer on USMLE if they say patient over 50 has neck pain + MRI shows
degenerative changes of cervical spine.
Can occur in lumbar spine, but USMLE likes cervical spine for this
Atlantoaxial
subluxation ??
- Increased mobility between the first (atlas) and second (axis) vertebrae
- Rheumatoid asthritis
- CT or flexion/extension x-rays of cervical spine prior to surgery
Q on one of the Neuro CMS forms gives patient with RA not undergoing surgery
who has paresthesias of upper limbs answer is just MRI of cervical spine
(implying atlantoaxial subluxation has already occurred)
Lumbar spinal stenosis ?
1.Spinal cord=Narrowing
The answer on USMLE if they mention a patient over 50 who has lower back
pain that’s worse when walking down a hill (i.e., relieved when leaning forward),
or when standing/walking for extended periods of time.
Cervical foraminal
stenosis ?
The answer on USMLE if they say old woman has difficulty fastening buttons +
weakness of hand muscles + loss of sensation of little finger à answer = “C7-T1
foraminal stenosis” (offline NBME 20).
Spondylolisthesis ?
The answer on USMLE if they a “step-off” between infra-/suprajacent vertebrae.
In other words, they’ll say one vertebra “juts out” or has a “step-off” compared to
those above/below it.
- Can be due to trauma or idiopathic development
Disc herniation
“herniated nucleus pulposus.”
Herniation of nucleus pulposus through a tear in annulus fibrosis
The answer on USMLE if they mention radiculopathy (i.e., shooting pain down a
leg) after lifting a heavy weight or bending over (e.g., while gardening). They can
write the answer as “herniated nucleus pulposus.”
Meralgia paresthetica?
- The answer on USMLE if they say patient has pain or paresthesias running down
the lateral thigh. - Due to entrapment of lateral femoral cutaneous nerve.
- Often seen as incorrect answer choice on Step, so at least be aware of it.
Sciatica ?
- 90% of the time is due to disc herniation.
- Straight-leg test classically (+) – i.e., reproduces radiating pain.
- Tx = Light exercise as tolerated + NSAIDs. Bed rest is wrong answer on USMLE.
- On one of the 2CK CMS forms, ibuprofen straight-up is listed as the answer.
Conus medullaris ?
- Refers to injury or lesion at the terminal part of the spinal cord, around T12 to
L2. - Acute-onset + bilateral leg weakness and/or pain.
- Urinary retention.
- Classically perianal anesthesia.
- Caused by trauma, tumors, vascular events.
“metastases to cauda equina.”
- USMLE likes disc herniation and metastases to the spine as highest-yield causes.
- For example, the Q can give 55-yr-old man with lower-limb neurologic findings +
urinary retention, and the answer = “metastases to cauda equina.”
Tethered cord ?
- Caused by abnormal attachment of the spinal cord to the wall of the spinal
canal, usually by scar tissue. - This attachment results in abnormal stretching of the spinal cord and variable
neurologic deficits. - Caused by myelomeningocele in pediatrics, or by trauma/surgery in adults.
- Diagnosis of exclusion on USMLE (meaning we eliminate to get there).
Scoliosis ?
- Can be associated with Marfan syndrome, Friedreich ataxia, NF1.
- Adams forward bend test used to diagnose.
- USMLE wants you to know most children do not need treatment, but that
curvatures will remain throughout life. - Answer = bracing if curvature is >25 degrees and child is still growing.
- I’ve never seen surgery as answer for scoliosis on NBME; literature says
recommended only when curvature >40 degrees
