Neuro 3 Flashcards
What is the water in ear test called and what does it do
Cold caloric testing
Ice water in ear and observe for conjugate eye deviation toward the ear injected (with nystagmus in the opposite direction?)
Cranial nerves involved in pupillary reflex
II (afferent) and III (efferent)
CN involved in oculocephalic reflex
VIII (afferent); III, IV, VI (efferent)
CN involved in caloric reflex
VIII (afferent); III, IV, VI (efferent)
CN involved in corneal reflex
V1 (afferent); VII (efferent)
CN involved in gag reflex
IX (afferent), X/XI (efferent)
CSF findings of bacterial meningitis (cells, protein, glucose, other)
♣ Cells = polymorphs
♣ Protein = high
♣ Glucose = low
♣ Other = culture and gram stain may be positive
CSF findings of viral meningitis (cells, protein, glucose, other)
♣ Cells = lymphocytes
♣ Protein = high
♣ Glucose = Normal
♣ Other = Viral PCR may be positive
CSF findings of TB meningitis
♣ Cells = lymphocytes
♣ Protein = high
♣ Glucose = very low
♣ Other = positive for acid-fast bacilli
CSF findings of Guillain-Barre
♣ Cells = none
♣ Protein = high
♣ Glucose = normal
CSF findings of MS
♣ Cells = Few lymphocytes
♣ Protein = slightly high
♣ Glucose = normal
♣ Other = oligoclonal bands usually present
CSF findings of Acute disseminated encephalomyelitis
♣ Ells = Lymphocytes or polymorphs
♣ Protein = usually high
♣ Glucose = normal
♣ Other = oligoclonal bands usually absent
CSF findings of SAH
♣ Cells = lymphocytes and many RBCs
♣ Protein = may be high
♣ Glucose = normal
♣ Other = Xanthochromia
Structural causes of depressed consciousness
Indicated by presence of focal signs
o Acute ischemic stroke ♣ Brainstem ♣ Unilateral cerebral hemisphere (with edema) o Acute intracranial hemorrhage ♣ Intraparenchymal ♣ Subdural ♣ Epidural o Brain tumor (with edema or hemorrhage) ♣ Primary ♣ Metastatic o Brain abscess
Diffuse cuases of depressed consiousness
Indicated by absence of focal signs
o Metabolic
♣ Electrolyte abnormality
• Hyponatremia, hypernatremia, hypocalcemia, hypercalcemia, hypomagnesemia, hypermagnesemia, hypophosphatemia
♣ Glucose abnormality
o Hypoglycemia, nonketotic hyperosmolar coma, diabeteic ketoacidosis
♣ Hepatic failure, uremia, thyroid dysfnction, adrenal insufficiency
o Toxic
♣ Alcohol, sedatives, narcotics, psychotropic drugs
♣ Other exogenous toxins (CO, heavy metals)
o Infectious
♣ Meningitis
♣ Diffuse encephalitis
o Hypoxic-ischemic
♣ Respiratory failure
♣ Cardiac arrest
o Others
♣ Subarachnoid hemorrhage
♣ Carcinomatous meningitis
♣ Seizures or postictal state
What should you always do before LP in a patient with decreased consciousness
CT head - to avoid precipitating brain herniation if a large intracranial mass is present
Next step in management of coma patient with focal signs
Urgent head CT imaging - looking for signs of stroke, hemorrhage, or mass lesion
Next step in managment of coma patient without focal signs
Extensive workup for metabolic, toxic, or infectious cause
Name 3 non-surgical ways to lower ICP
Elevate head
Hyperventilation
Mannitol (osmotic diuretic)
What is the difference between Wernicke encephalopathy and Korsakoff syndrome
Wernicke encephalopathy
o Triad: confusion, ophthalmoplegia, ataxia
o Reversible with Thiamine administration
Korsakoff syndrome:
o Confabulation, personality change, memory loss (permanent)
Describe vision with defect at optic nerve
Single eye blindness (anopia)
Describe vision with defect at optic chiasm
Bitemporal hemianopia (no vision in temporal fields)
Describe vision with defect at optic tract
Homonymous hemianopia (loss of vision on either R or L side)
Describe vision with defect at temporal optic radiation (Meyer’s loop)
Homonymous superior quadrantanopia (Pie in the sky)
Describe vision with defect at parietal optic radiation
Homonymous inferior quadrantanopia (pie on the floor)
Describe vision with defect at occipital cortex
Homonymous hemianopia with macular sparing
Describe sympathetic pathway to the pupil
o 1st order neuron: starts in ipsilateral hypothalamus and projects down the brainstem to the intermediolateral cell column at C8-T1 spinal level
o 2nd order neuron: travels from spinal cord via anterior horn / ventral root to the superior cervical ganglion
o 3rd order neuron: passes frpm superior cervical ganglion via carotid artery surface, through the cavernous sinus. In the cavernous sinus the fibers briefly join CN VI and then enter the orbit through the superior orbital fissure along with the ophthalmic branch (V1) of trigeminal nerve CN V via the long ciliary nerves. The long ciliary nerves then innervate the iris dilator and the Muller muscle, along with the blood vessels of the eye
Describe parasympathetic pathway to the pupil
o Initial pupillary reaction: retina -> optic nerve -> chiasm -> optic track, which then synapses with the pretectal midbrain nucleus
o Interneurons send signal from pretectal nucleus to bilateral Edinger-Westphal nucleus, situated in the rostral aspect of the third nerve nucleus
o Efferent parasympathetic fibers from the EWN travel with CN III. In the cavernous sinus they run with CN III and ultimately synapse in the ciliary ganglion located in the posterior orbit
o Parasympathetic fibers then innervate the pupilloconstrictor msucle
Effects of cocaine eye drops in Horner’s
Cocaine eye drops fail to dilate the abnormal pupil
Causes of 1st order neuron Horners
♣ Hypothalamic infarcts, tumor
♣ Mesencephalic stroke
♣ Brainstem: ischemia, tuor, hemorrhage
♣ Spinal cord: syringomyelia, trauma
Causes of 2nd order neuron Horner’s
♣ Cervicothoracic cord/spinal root trauma
♣ Cervical spondylosis
♣ Pulmonary apical tumor: Pancoast tumor
Causes of 3rd order neuron Horners
♣ Superior cervical ganglion (tumor, iatrogenic)
♣ Internal carotid arter: dissection, trauma, thrombosis, tumor
♣ Base of skull: tumor, trauma
Cavernous sinus: tumor, inflammation, aneurysm, thrombosis, fistula
Describe progression of sx in CN III palsy due to compression
Because parasympathetic fibers run in outer part of nerve and motor fibers are more internal, compressino of the nerve initially produces a dilated pupil (mydriasis) without compromising eye movements
Describe progression of sx in CN III palsy due to vascular problems
Will produce pupil-sparing IIIrd nerve lesion in which pupil is normal but there is palsy of the ocular muscles
What direction will eye point with dysfunction of CN III
down and out
What is the function of MLF
Connects the contralateral abducens nucleus and paramedian pontine reticular formation (PPRF) with ipsilateral IIIrd nerve nucleus
Describe one and a half syndrome
♣ Lesion affects ipsilateral PPRF or CN VI and ipsilateral MLF
♣ Ipsilateral conjugate horizontal gaze palsy (“one”) + ipsilateral INO (“half”)
♣ Only remaiing horizontal movement is contralateral abduction (cannot look ipsilaterally on either eye)
♣ Failure of medial recturs to move synchronously with contralateral lateral rectus
♣ Abducting eye will then have nystagmus back to midline
Describe sx of INO
♣ Failure of medial rectus to move synchronously with contralateral lateral rectus
♣ Abducting eye will then have nystagmus back to midline
Adduction during conversion is spared
Describe pathway of voluntary eye movement
o Frontal eye fields (R) located around lateral part of precentral sulcus
o Descends ipsilaterally until crossing midline late in pons to project to contralateral (L) paramedian pontine reticular formation (PPRF)
o The contralateral (L) PPRF sends projections to:
♣ Contralateral (L) abducens nucleus (CN VI)
♣ Crossing back to R early in pons and up R medial longitudinal fasciculus to R oculomotor nucleus (CN III)
How do you diagnose Parkinsons
Clinical diagnosis based on physical exam (resting tremor, rigidity, bradykinesia, postural instability)
What is one of the earliest and most unique sx of Parkinsons
Loss of smell
Draw out brachial plexus
DO IT!
