Neurology USMLE Exam Questions
and Correct Answers (Already
Graded A+)
What if a kid produces too much IgA? How can this lead to meningitis? - Answer-Too
much serum IgA can bind to and block Neisseria, blocking the binding of IgG and IgM
which can induce complement mediated lysis. IgA doesnt trigger complement so
bacteria escape immune killing.
What complement factors make the membrane attack complex? - Answer-C5b - C9
Lipid laden macrophages containing the products of myelin breakdown are seen in what
disease? - Answer-MS. they are seen along w the demyelinating plaques. CSF shows
increased IgG. Found as oligoclonal band on protein electrophoresis. Visual evoked
potentials are used to assess conduction velocity, which slows in MS due to
demyelination. They also have astrocyte proliferation.
I am 34, w diplopia, numbness of right hand 6 months ago, that resolved without
treatment. I have oligoclonal bands on electrophoresis of CSF. What are these bands
made of? - Answer-IgG. The CSF of patients w MS have oligoclonal bands.
Depletion of oligodendrocytes is characteristic of the plaques in MS patients, but
another disease related to reactivation of a virus in HIV patients causes this
phenomenon. What is the disease? - Answer-Progressive Multifocal
Leukoencephalopathy. JC virus reactivation.
A neuron is being studied. The equilibrium potential is mapped as a curve. It shows a
flat line, followed by a sharp increase, followed by a decrease. Is the decrease due to
Ca or Cl? - Answer-Chloride. This was the tricky question 386664 where you needed to
use the equlibrium potentials of various ions (given) to determine what the final ion was
that moved through the cell. It was Cl because the Eq was -90, not Ca because its
potential is +125. You were hasty in answering and missed this easy question.
What are the three typical components of a Do Not Resuscitate order, meaning what 3
interventions are not allowed? - Answer-No intubation or mechanical ventilation
No defibrillation
No IV drugs to acutely treat a terminal rhythm
Patients may additionally specify wished such as the desire not to be fed artificially or
any other limitations.
,If a patient has no DNR or advance directive, but the wife says that he clearly did not
want to be resuscitated, and mentioned that on many occasions, what do you do in the
event he enters a terminal rhythm like V-fib w no spontaneous respirations? - Answer-
you attend to his comfort and ensure his family is present as he is dying. If you have no
written documentation, the next of kin (here, the wife) becomes in charge based on
what the patient would have wanted. The next of kin is the spouse, then adult children,
then parents, grandparents, aunts/uncles, adult cousine, so on.
Describe the path of flow of CSF - Answer-Choroid plexus in lateral ventricles (infected
by Neisseria) --> 2 interventricular foramen of Monroe --> Third ventricle --> Cerebral
aqueduct --> Fourth ventricle --> 2 FOramena of Luscka and foramen of Magendie
(middle) to subarachnoid space. CSF then is absorbed by arachnoid granulation into
venous sinuses. The dynamic balance between production and absorption allows stable
intracranial volume (120-150 ml) and pressure (50-80 mm H20)
What is normal intracranial volume and pressure? - Answer-The dynamic balance
between production and absorption allows stable intracranial volume (120-150 ml) and
pressure (50-80 mm H20)
If you have non-communicating hydrocephalus, as would happen w a tumor, which
ventricles grow large: Those above or below the tumor? - Answer-Above. Congenital
malformations such as aqueductal stenosis, Arnold Chiari or Dandy Walker
malformations cause this. The obstacle to CSF flow is in the ventricles.
___________ hydrocephalus usually occurs secondary to dysfunction or obliteration of
the arachnoid granulations. - Answer-Communicating. Sequelae of meningeal infections
such as TB, or subarachnoid/intraventricular hemorrhage. In communicating
hydrocephalus, the ventricles are symmetrically enlarged.
The ________ veins pass through aperatures between the intracranial sinuses and
veins outside the cranial vault. They do not participate inabsorption of CSF - Answer-
Emissary veins
Symmetrical enlargement of ventricles is a characteristic of ___________
hydrocephalus, which occurs secondary to dysfunction or obliteration of subarachnoid
villi. The dysfunction is usually a sequelae of meningitis (such as TB) or
subarachnoid/intraventricular hemorrhage. - Answer-Communicating hydrocephalus
A 23 year old patient is being evaluated for myoclonic epilepsy of recent onset.
Episodes are short-lived, triggered by startle. PE shows proximal muscle weakness.
Gomori trichrome stain shows a muscle biopsy w muscle fibers that are blotchy red. NO
FH becuase patient is adopted. What is the chance he will pass on this disease to
offspring?
0%
25%
50%
, 75%
100% - Answer-Zero. Blotchy red fibers on Gomori trichrome stain is mitochondrial
myopathy. In these conditions, abnormal mitochondria accumulate under the
sarcolemma of muscle fibers. The fibers have an irregular shape and size on cross
section. For this reason these are also called the red fiber disease. EM shows increased
numbers of large abnormally shaped mitochondria.
Myoclonic epilepsy w ragged red fibers (MERRF), Leber optic neuropathy (blindness),
and mitochondrial encephalopathy w stroke like episodes and lactic acidosis (MELAS)
Blotchy red fibers on Gomori trichrome stain is characteristic of what disease? -
Answer-Mitochondrial myopathies
What is the inheritance pattern of: Myoclonic epilepsy w ragged red fibers (MERRF) -
Answer-mitochondrial. Mutations, deletions, or duplications of mitochondrial DNA.
Because sperm mitochondria are in the tail and dont pass into ovum during fertilization,
only maternal mitochondria are transmitted to the fetus.
What is the inheritance pattern of: Leber optic neuropathy (blindness) - Answer-
Mitochondrial. Mutations, deletions, or duplications of mitochondrial DNA. Because
sperm mitochondria are in the tail and dont pass into ovum during fertilization, only
maternal mitochondria are transmitted to the fetus.
What is the inheritance pattern of a certain encephalopathy w stroke like episodes and
lactic acidosis (MELAS) - Answer-Mitochondrial. Mutations, deletions, or duplications of
mitochondrial DNA. Because sperm mitochondria are in the tail and dont pass into
ovum during fertilization, only maternal mitochondria are transmitted to the fetus.
What causes the mitochondrial diseases? - Answer-Mutations, deletions, or duplications
of mitochondrial DNA. Because sperm mitochondria are in the tail and dont pass into
ovum during fertilization, only maternal mitochondria are transmitted to the fetus.
A 24 year old male is evaluated for chronic headaches and visual changes. Intracranial
calcified mass is seen on MRI. Gross insp shows cystic spaces w thick brownish fluid
rich in cholesterol. The mass most likely shares a common origin w which:
A. Choroid plexus
B Pineal gland
C. Pituitary gland
D. Cerebellar vermis
E. Retina - Answer-Pituitary gland. Calcified cystic mass in a young adult w no other
risks is likely a Craniopharyngioma. Suprasellar region. Cystic or partially cystic w solid
areas. LM shows stratefied squamous epith and possibly Keratin pearls. Cysts are filled
w yeloow viscous fluid rich in cholesterol crystals.
Derived from Rathke's pouch remnants. Rathke's pouch is an evagination of the
ectoderm that lines the fetal oral cavity. It protrudes up to form the anterior pituitary
gland. Posterior pit is neuroectoderm.
