Neurology Flashcards
thymoma + EOM weakness =?
MOA?
Myasthenia gravis
Antibodies against a neurotransmitter NICOTINIC receptor (Ach)
The receptor is a PLASMA MEMBRANE protein.
Note: overdose of neostigmine can cause desensitization of the nicotinic receptors
HIV patient, irregularly shaped pupils that dont react to light is called what? Assoc with what disease and features?
Argyll robertson pupils
Tertiary Syphillis, tabes dorsalis
Posterior inferior cerebellar artery occlusion causes what syndrome?
Symptoms?
PICA can occur with cervical spine trauma with dissection of what artery?
Lateral medullary syndrome (wallenberg)
vertigo/nystagmus, ipsilateral cerebellar signs, loss of pain/temp on ipsilateral face, contralateral body, bulbar weakness, ipsilateral horner syndrome
Vertebral artery
What type of necrosis occurs in the brain?
How is it characterized?
Liquefactive
complete digestion and removal of necrotic tissue with formation of cystic cavity - assoc with large amounts of lipids and lysosomal enzymes
Occlusion of what artery causes contralateral hemiplegia of the face and upper limb with preservation of lower limb? L facial weakness spares the forehead
MCA
also supplies Broca and Wernicke’s area
Obstructive hydrocephalus (papilledema, headache, vomiting) and dorsal midbrain syndrome is due to what? Describe reaction to light and gaze
Pineal gland mass
Light - pupils react to accomodation but not light
Gaze - upward limited, downward preference.
progressive forgetfulness, learning difficulty and poor recall due to problem with what structure?
hippocampal formation
Neuro deficits that cannot be explained by a single lesion indicates what disease?
What is it characterized by?
Multiple sclerosis
Demyelination of axons in white matter (loss of OLIGODENDROCYTES). White matter plaques. Optic neuritis, intention tremor.
CSF has inc IgG, oligoclonal band on protein electrophoresis (autoimmune process).
Note: sx worse with HEAT because dec axonal transmission assoc with inc heat.
Ipsilateral shoulder pain, upper limb paresthesias and areflexic arm weakness can be a sign of what?
pancoast tumor near superior sulcus involving the brachial plexus. Can also involve cervical symp ganglia
NT found in raphe nuclei of brainstem?
Serotonin
NT found in caudate nucleus and putamen?
GABA
NT found in locus ceruleus? Located in posterior rostral pons near the lateral floor of the 4th ventricle
NE
NT found in nucleus basalis of Meynert?
Acetylcholine
NT found in red nucleus?
None. Involved in motor coordination
NT found in the substantia nigra?
Dopamine
Chronic sx of headaches, dec libido, meningeal irritation, bitemporal hemianopsia, cardiovascular collapse is a sign of what?
Pituitary apoplexy (acute hemorrhage into the pituitary gland)
Synaptophysin stain what?
CNS tumors of NEURONAL origin (neurons, neuroectodermal, neuroendocrine cells)
Glial fibrilllary acidic protein (GFAP) stain what?
neoplasms of GLIAL origin (astrocytomas, ependymomas, oligodendrogliomas)
MCC of spontaneous deep intracerebral hemorrhage?
Hypertensive vasculopathy of small penetrating branches of the major cerebral arteries (lenticulostriate arteries - branch of MCA that supplies basal ganglia)
Why doesnt axonal regeneration occur in the CNS?
Persistence of myelin debris suppress axonal growth via myelin-assoc inhib factors
Glial scar= barrier
Hydrocephalus in infants (Eg in lateral ventricles) if left untreated can lead to what?
Muscle hypertonicity due to stretching of periventricular pyramidal tracts, developmental delays, and seizures
Which skull foramen does CN I olfactory bundles go through?
Cribiform plate
Which skull foramen does CN II, ophthalmic aa, central retinal vein go through?
Optic canal
Which skull foramen does CN III, IV, V1, VI, ophthalmic v, sympathetic fibers go through?
Superior orbital fissure
Which skull foramen does CN V2 (maxillary) go through?
Foramen rotundum
Which skull foramen does CN V3 (mandibular) go through?
Foramen ovale
Which skull foramen does Middle meningeal aa and vv go through?
Foramen spinosum
Which skull foramen does CN VII, VIII go through?
Internal acoustic meatus
Which skull foramen does CN IX, X, XI, jugular v go through?
Jugular foramen
Which skull foramen does CN XII go through?
Hypoglossal canal
Which skull foramen does spinal roots of CN XI, brainstem, vertebral aa go through?
Foramen magnum
Acute nausea after systemic chemo is from stimulation of the chemoreceptor trigger zone (CTZ) in the area postrema of what part of the brain?
dorsal medulla near the 4th ventricle
What is the key neuro-anatomic landmark for locating the trigeminal nerve on CT?
Middle cerebellar peduncles. Trigeminal n exits the brainstem at the lateral aspect of the midpons at this level.
What channels are important for generation and propagation of AP?
What channels are essential for fusion and release of NT vesicles into the synaptic cleft?
- Voltage-gated Na channels
2. Voltage-gated Ca channels
Multiple vacuoles seen in gray matter of the brain on microscopic exam
Creutzfeldt-Jakob disease (spongiform encephalopathy)
Loss of neurons of the anterior horns of the spinal cord; demyelination of lateral corticospinal tract
ALS
LMN and UMN lesions respectively
Damage to motor neurons of the anterior horn
polio - flacid paralysis, atrophy, areflexia
LMN damage
Degeneration of dorsal (posterior) and lateral spinal columns
Vit B12 def
Brain tumor gross exam showing areas of necrosis and hemorrhage
Micro: pseudopalisading tumor cells around area of necrosis
glioblastoma multiform (MC primary brain tumor in adults)
Myasthenia gravis is due to antibodies to which protein?
Nicotinic acetylcholine receptor
Seizure type? consciousness unaffected; affects only 1 area of the brain
Simple partial
Seizure type? consciousness impaired; affects only 1 area of the brain
Complex partial
Increased ICP does what to bp and HR? What is the Cushing reflex?
Increase BP, decrease HR
Cushing reflex = resp depression in setting of inc ICP in addition to the above
The sympathetic pathway causes Horner syndrome. List 3 examples in the pathway that can cause it.
- Descending hypothalamics (first-order neuron) - strokes, tumors, demylinating disease
- Pancoast tumors (affect 2nd order neurons at T1 level) - UNILATERAL ARM PAIN also seen
- Carotid dissection (third-order neuron along the internal carotid)
Left-sided sensory neglect is typically caused by lesion where?
R parietal or frontal lobe
Infant with weak sucking, hypotonia, areflexia, and fibrilation potentials on EMG, resp failure
Ventral horn defect - Werdnig-Hoffman disease (lower motor neuron disease)
What type of hematoma can present several days or up to 3 weeks following a traumatic head injury?
Chronic or subacute subdural hematoma
Rupture of bridging veins; crescent shaped
Inability to recognize faces due to lesion of the non-dominant occipital cortex or bilateral lesions of the fusiform gyri
Prosopagnosia
Lack of knowledge about one’s own body (eg deny half of one’s body belongs to the patient)
Asomatognosia
Lesion of angular gyrus causes alexia, agraphia, acalculia, finger agnosia, and R-L disorientation
Gerstmann syndrome
Tensilon test (admin edrophonium) in myasthenia gravis indicates what if:
- improves symptoms
- Does not improve sx
- Undertreated
2. Cholinergic crisis
Damage to what part of the CNS results in decorticate (flexur) posturing?
Brainstem at/below the level of the red nucleus (eg midbrain tegmentum, pons)
Right-sided pure hemisensory loss is likely due to what type of stroke?
Ventral posterior THALAMUS stroke (receives input from the spinothalamic tract and dorsal columns)
small vessel occlusion (eg due to lipohyalinosis and microatheroma formation) in the penetrating vessels supplying the deep brain structures
lacunar infarcts (DM and HTN are risk factors)
Injury to what part of the brain causes executive dysfunction and personality changes?
Left sided frontal lobe injury most common
Meningioma compressing the parietal lobe (post central gyrus) results in what sx?
contralateral sensory loss in lower limb - this is the somatosensory cortex
What do the ACA, MCA, and PCA branch from?
Internal carotid arteries. They supply most of the brain except the cerebellum, brainstem and medial occipital lobes (these are supplied by the basilar artery)
Hemisection of the spinal cord at C7 on the L causes what sx?
Lesion of L gracile fasciculus - Loss of conscious proprioception and vibration sensation in the L leg
Does Myasthenia gravis or Lambert-Eaton myasthenic syndrome cause loss of tendon reflexes?
Lambert eaton (paraneoplastic synd assoc with small cell carcinoma of the lung - also proximal mm weakness, CN involvement, autonomic sx like dry mouth and impotence)
What drugs can exacerbate MG symptoms?
Drugs with antinicotinic effects
aminoglycosides (inhibit protein synth and is neuromuscular blocker)
Procainamide, chloroquine, ciprofloxacin, mm relaxants, botulinum toxin, quinidine, phenytoin, penicillamine
Space occupying lesions in the temporal lobe increasing ICP causes what symptoms?
inc ICP –> UNCAL herniation –> compress ipsilateral CN 3 –> oculomotor n plasy w/fixed dilated pupil
MOA for the drug used to treat muscle rigidity associated with NMS from antipsychotic med overdose?
Dantrolene - Inhibition of calcium ion release from sarcoplasmic reticulum of skeletal muscles
What nerves pass through the cavernous sinus? Symptoms of thrombosis?
CN III, IV, VI, V1, V2
Infection of sinuses or teeth can cause thrombosis –> headache, fever, diplopia, ocular mm paralysis
CN III palsy can also cause ptosis and mydriasis
CN V causes loss of upper facial sensation and afferent corneal reflex
MCC of spontaneous lobar hemorrhage (multifocal) in elderly?
Cerebral amyloid angiopathy
MCC of intracranial hemorrhage in children (single lesion)
AVM
How does def in Vit B6 cause neuropathy?
Defective synthesis of NT like GABA.
Which nerve innervate mm of facial expression?
Which nerve is for sensation of the face?
Which will be affected by parotid tumor?
Facial expression - CN 7
Sensation - CN V (also motor to mm of mastication)
Facial affected by parotid tumor. CN V is too deep.
impaired rapid alternating movements
dysdiadochokinesia (seen with cerebellar hemisphere problems) Limb dysmetria (overshoot/undershoot targeted mvt) and intention tremor are also related to cerebellar hemisphere problems.
Location of: Schwannoma? Meningiomas? Glioblastoma? Oligodendrogliomas?
Schwannoma - cerebellopontine angle (vestibular branch of CN VIII) - S100 (neural crest origin), biphasic cellularity
Meningioma - arachnoid cells (dural reflection) - well-circum, whorled pattern, psammoma bodies. At falcine
Glioblastoma - within cerebral hemispheres (necrosis and hemorrhage seen)
Oligodendrogliomas - white matter of cerebral hemisphere. Calcification seen
Neonatal intraventricular hemorrhage usually occurs where?
Germinal matrix
Common complication of prematurity
Symmetric proximal m weakness. Mm bx shows inflam necrosis, regen of mm fibers, over-expression of MHC class I on sarcolemma –> infiltratoin with CD8 T lymphocytes and myocyte damage
Polymyositis
Differentiate sensory ataxia from cerebellar ataxia
Romberg test
Positive = sensory ataxia (defect in posterior column or peripheral nerves - eg tabes dorsalis or vit B12 def)
Negative = cerebellar ataxia (impaired motor coordination –> test with rapid alternating movements)
Lumbosacral radiculopathy L4 L5 S1 S4
L4 - sensory loss of antlat thigh, knee, medial calf, dec patellar reflex
L5 - sensory loss of butt, postlat thigh, dorsal foot
S1 - sensory loss of butt, post thigh, calf, lat foot, weak achilles reflex
S4 - Saddle anesthesia, loss of anocutaneous reflex (assoc w/ damage to S2-4)
Normal pressure hydrocephalus causes urinary incontinence how?
Stretching of cortical fibers - these fibers control the bladder.
Note: micturation is regulated by these other centers:
- sacral micturation center (s2-s4) parasymp fibers
- pontine micturation center - in pontine reticular formation (coordinates relaxation of external urethral sphincter with bladder contraction)
CN VII functions
- motor to facial mm
- parasymp to lacrimal, submandibular, and sublingual salivary glands
- special afferent for taste to ANTERIOR 2/3 of tongue
- somatic afferents from the pinna and external auditory canal
Function of arachnoid granulations and choroid plexus
Arachnoid - Absorb CSF –> venous sinuses
Choroid plexus -CSF secretion
Temporomandibular disorder can affect what nerve that supplies the middle ear and mm of mastication?
CN V - mandibular division V3
largest branch of trigeminal
UMN signs - corticospinal tracts
LMN signs - anterior horn
UMN - spasticity, clasp-knife rigidity, hyperreflexia, Babinksi. UMN lesions can affect any part of the pyramidal motor system (corticospinal tract of spinal cord, brainstem, internal capsule, precentral gyrus)
LMN - flaccid paralysis, hypotonia, hyporeflexia, mm atrophy and fasciculations
Thoracic outlet symptoms? What mm compresses the lower trunk of the brachial plexus?
upper extremity numbness, tingling, and weakness
Scalenes
CN 9 functions
- Motor: stylopharyngeus (elevates larynx when swallowing)
- Parasymp: parotid gland secretion
- General sensory: tympanic membrane, eustachian tube, posterior 1/3 of tongue, tonsillar region, upper pharynx (afferent portion of gag reflex), carotid body, and carotid sinus
- Special sensory: taste to posterior 1/3 of tongue
Global cerebral ischemia (hypoxic-ischemic encephalopathy) is a result of systemic hypoperfusion. What cells are most susceptible to ischemia?
Pyramidal cells of the hippocampus - first area damaged
Neocortex of the Purkinje cells of the cerebellum
Gross: bilateral wedge-shaped strips of necrosis over the cerebral convexity, parallel and adjacent to the longitudinal cerebral fissure (watershed zones of the major cerebral arteries)
Why does glucose infusion in thiamine deficiency precipitate encephalopathy?
Thiamine is a cofactor for enzymes responsible for glucose metabolism. Infusion of glucose will exacerbate the pre-existing thiamine deficiency, often precipitating Wernicke encephalopathy (damage to mamillary bodies)
patients with cavernous hemangiomas are at greatest risk of developing what complication?
Intracerebral hemorrhage.
Seizures are common as well.
Appear as irregular hyperdense/bright mass on CT
What type of brain hematoma is associated with a lucid interval followed by loss of consciousness?
Epidural hematoma
Between Skull and dura (lens shaped and assoc w/middle meningeal artery)
What neurological finding will persist despite treatment of Wernicke encephalopathy with thiamine?
memory loss and confabulation
Oculomotor dysfunction, ataxia, and confusion will resolve
Subarachnoid hemorrhage is usually d/t what?
Rupture of saccular berry aneurysms or AVMs.
Note berry aneurysms of the circle of Willis are assoc with ADPKD
Worst HA of life.
Charcot-Bouchard aneeurysms are small (<1mm) and occur in patients with what?
Long-standing HTN
Found in arterioles that supply the basal ganglia, internal capsule, and deep white matter.
Cause intracerebral hemorrhage
Pterion is the region of the skull where the frontal, parietal, temporal and sphenoid bones meet. Skull fractures here may cause laceration of what vessel?
Middle meningeal artery (branch of maxillary artery) –> epidural hematoma
What are the major dopaminergic pathways in the brain?
- Mesolimbic and mesocortical: regulate cognition and behavior
- Nigrostriatal path: regulates coordination of voluntary movements
- Tuberoinfundibular path: inhibits prolactin secretion (can cause hyperprolactinemia if blocked by antipsychotics)
Parkinson disease reduces activity of the THALAMUS and its projects to the cortex –> bradykinesia and rigidity. Intractable sx may benefit with high-freq deep brain stim of what part of the brain?
Globus pallidus internus or subthalamic nucleus - promotes thalamo-cortical disinhibition with improved mobility.
Wernicke aphasia (impaired comprehension and fluent speech) is caused by a lesion in what gyrus?
superior temporal gyrus
Broca’s aphasia (slow, effortful speech that is agrammatic and telegraphic) is caused by a lesion in what gyrus?
inferior frontal gyrus
Loss of somatic sensations (touch, pain, and temp) in the region of the body assoc with the portion of the sensory homunculus is caused by a lesion in what gyrus?
postcentral gyrus (in parietal lobe and is the primary somatosensory cortex)
Spastic paresis on the contralateral side of the body in the region assoc with the motor homunculus is caused by a lesion in what gyrus?
precentral gyrus (in the frontal lobe and is the primary motor cortex)
Inapprop social behavior, loss of ability to problem-solve, loss of initiative, abstracting ability, concentration and judgment is caused by a lesion where?
prefrontal cortex
Bromocriptine MOA?
Dopamine D2 agonist.
Note: improves galactorrhea in patients with prolactinomas. Dopamine restrains prolactin production
What cell type promotes axonal regeneration?
Schwann cells
Cochlear implants convert sound energy to electrical signals by stimulation of what structures?
Auditory nerve endings in the cochlea
Cochlear implants bypass damaged hair cells and convert speech and environmental sounds into electrical signals and send these signals to the hearing nerve.
Man with upper and lower extremity weakness, atrophy of hand mm, diffuse hyperreflexia, fasciculations of mm of hands and upper extremities with normal sensation has what?
ALS
UMN - hyperreflexia
LMN - fasciculations
Eventually have difficulty swallowing and resp complications
Tx: Rilozule (inhibit glutamase release. Baclofen (Gaba-b Agonist) for spasticity.
Form of stroke characterized by oculomotor n palsy and contralateral hemiparesis or hemiplegia
Weber’s syndrome
occlusion of perforating branch of PCA
Note: does not affect pain or temp unlike Lateral medullary synd
Progressive difficulty walking, weak and dec muscle bulk of lower extremities, and diminished patellar and achilles tendon reflexes with preserved sensation indicates what?
Degeneration of motor neurons of the lumbar cord - LMN
The leg is innervated by many things, but the femoral, obturator, and sciatic all come (at least partially) from the lumbar spine. If you lost the LMN cell bodies (in the ventral and lateral horns of the lumbar spine), that would cause the symptoms seen here.
Difficulty walking, leg pain, atrophy of lower extremities and hammer toes with high-stepping gait. Nerve biopsy shows what? Dx?
Abnormal myelin sheaths
Dx - Charcot Marie Tooth
Patient in MVC with the following: - R cerebral cortex injury with complete paralysis of LLE - R mid humerus fx severing radial n - R tibia fracture After 10 weeks, which deep tendon reflex is strongest of the following: - L achilles tendon - L biceps tendon - R brachioradialis tendon - R patellar tendon
Pt has complete paralysis of LLE, meaning spinal cord injury on the left at L2. The right sided fractures would be LMN lesions causing hyporeflexia/areflexia, so cross off those two. Left biceps should be normal ~ 2+. The key is “after 10 weeks,” which means he should have recovered from spinal shock (during which left achilles reflex would be minimal).
!!!After recovering from spinal shock, reflexes become very hyperreflexive, so left achilles should be correct.
Cause of severe constipation with no abnormalities on colonoscopy and no relief with laxatives?
Pelvic splanchnic nerve dysfunction
(provide parasympathetic innervation to the hindgut; s2-s4)
intrinsic ganglia of descending and sigmoid colon, rectum, and inferior hypogastric plexus and ganglia to the pelvic viscera
Weakness of L leg - pos babinski, dec somatic sensation in L foot, agraphesthesia on plantar surfaces, dec position sense in toes. Location of lesion?
R paracentral gyrus
Paracentral lobule is on the medial surface of the hemisphere and is the continuation of the precentral and postcentral gyri. The paracentral lobule controls motor and sensory innervations of the contralateral lower extremity. It is also responsible for control of defecation and urination.
Fracture of the lower jaw can potentially injure what nerve?
inferior alveolar nerve (sometimes called the inferior dental nerve) is a branch of the mandibular nerve, which is itself the third branch (V3) of the trigeminal nerve (cranial nerve V).
supply sensation to the lower teeth.
Uncontrollable irregular movements on the left side of the body is likely due to damage of nuclei?
RIGHT subthalamic - hemiballisumus
small lens-shaped nucleus in the brain where it is, from a functional point of view, part of the basal ganglia system
impaired activity of what gene protein is likely to cause astrocytomas?
Mutations that alter the function of the p53 gene product are thought to play a critical role in astrocytoma tumorigenesis
What causes absence seizures?
Synchronized discharge of thalamocortical neurons
