Neurology Flashcards
Alar and Basal plate
Alar (Dorsal) - Sensory
Basal (Ventral) - Motor
Separated by sulcus limitans
Derivatives of…
Prosencephalon
Mesencephalon
Rhombencephalon
Telencephalon (Cerebrum, Lateral ventricles)
Diencephalon (Thalamus/Hypothalamus, 3rd ventricle)
Mesencephalon (Midbrain, Aqueduct)
Metencephalon (Pons/Cerebellum, Upper 4th ventricle)
Myelencephalon (Medulla, Lower 4th ventricle)
Derivatives of…
Neuroectoderm
Neural crest
Mesoderm
CNS neurons, Ependymal cells, Oligodendroglia, Astrocytes
PNS neurons, Schwann cells
Microglia
Increased AFP
Increased AChE
Meningocele
Meningomyelocele
Note - In spina bifida occulta (tuft of hair, skin dimple) only bony vertebrae fails to fuse so AFP is normal
Increased AFP
Polyhydramnios (swallowing center)
Associated with…
Maternal T1DM
Low folate
ANENCEPHALY
Malformation of anterior neural tube - No forebrain and open calvarium
Mutation responsible for holoprosencephaly - May present anywhere from cleft lip/palate to cyclopia
Associated with…
Patau syndrome
Fetal alcohol syndrome
Sonic hedgehog signaling pathway - failure of left and right hemispheres to separate
example of developmental field defect (initial embryonic disturbance causes multiple malformations)
Cause of hydrocephalus in lumbosacral meningomyelocele
CHIARI II MALFORMATION
Herniation of cerebellar vermis and tonsils through foramen magnum with aqueductal stenosis
Cystic enlargement of 4th ventricle in posterior fossa
Noncommunicating hydrocephalus
Spina bifida
DANDY-WALKER SYNDROME
Agenesis of cerebellar vermis
Cape-like loss of pain and temperature
Fine touch preserved
loss of upper extremity pain and temperature sensation
Associated with…
Chiari I malformation (cerebellar tonsillar ectopia –> headache and cerebellar symptoms)
Trauma
Tumors
SYRINGOMYELIA
Fibers crossing anterior white commissure - Spinothalamic tract
damage to ventral white commissure and ventral horns
Taste and sensation on anterior, posterior, and base of tongue
Anterior (Arches 1/2):
Taste - Chorda tympani (CN VII)
Sensation - Lingual (CN V3)
Posterior (Arches 3/4)
Taste/Sensation - CN IX
Base (Arches 3/4)
Taste/Sensation - Internal Laryngeal (CN X)
Note - All motor function is by CN XII except the palatoglossus (CN X)
Nissl staining does not show…
Axon - no RER
Cell marker for cell involved in... Physical support/repair BBB Excess neurotransmitter removal K+ metabolism Glycogen fuel reserve
GFAP (Astrocyte)
Responsible for reactive gliosis in response to neural injury
Note - GFAP stains all Glial cells (Astrocytes, Oligodendrocytes, Ependymal cells), while Synaptophysin stains neurons
Fuse to form multinucleated giant cells in CNS of HIV patients - Not discernible by Nissl stain
MICROGLIA
Internal acoustic meatus tumor extending to cerebellopontine angle - GFAP+
VESTIBULAR (CN VIII) SCHWANNOMAS
Difference between oligodendrocytes and Schwann cells
Oligodendrocytes (CNS) can myelinate many axons, while Schwann (PNS) can only myelinate one
Fast adapting receptors responsible for…
Dynamic light touch
Vibration/Pressure
Meissner - Glabrous skin
Pacinian - Deep skin, Ligaments, Joints
Note - Both large, myelinated
Slow adapting receptors responsible for…
Pressure, Slippages, Joint angle change
Pressure, Static touch, Position sense
Ruffini - Dendritic endings with capsules
Merkel - Large, myelinated
Pain/Temperature receptors in skin and viscera
FREE NERVE ENDINGS
C (slow, unmyelinated) and Ad (fast, myelinated) fibers
Layer of peripheral nerve with inflammatory infiltrate in GBS
Endoneurium - invests single nerve fiber
Layer of peripheral nerve that must be attached in microsurgery
Perineurium - surrounds a fascicle of nerve fibers
Note - All fascicles and blood vessels surrounded by epineurium
Location of synthesis of... Acetylcholine Dopamine GABA Norepinephrine Serotonin
Basal Nucleus of Meynert
Ventral Tegmentum/SN pars compacta
Nucleus Accumbens
Locus Ceruleus (posterior rostral pons)
Raphe Nucleus
Mechanism of glucose and amino acid transfer through BBB
Carrier-mediated transport
Note - Nonpolar/lipid-soluble substances can cross rapidly by diffusion
Areas with BBB containing fenestrated capillary endothelium
Area postrema
OVLT (osmotic sensing)
Neurohypophysis
Mechanism of vasogenic edema
Neoplasms and infarction destroy BBB endothelial tight junctions
Function of locations of hypothalamus…
Lateral Ventromedial Anterior Posterior Arcuate Paraventricular Supraoptic Suprachiasmatic Tuberomammillary
Hunger (Ghrelin) Satiety (Leptin) Cooling (Parasympathetic) Heating (Sympathetic) Dopamine, GnRH, GH ADH, Oxytocin, CRH, TRH ADH, Oxytocin Circadian rhythm Arousal
Mechanism of circadian rhythm control by light
SCN releases NE
NE acts on the pineal gland
Pineal gland releases Melatonin
Note - Circadian rhythm controls nocturnal release of ACTH and Prolactin as well
Controls extraocular movements during REM sleep
PPRF (Paramedian pontine reticular formation/conjugate gaze center)
Note - Increased ACh in REM
Substances associated with decreased REM and delta wave sleep
Alcohol
Benzodiazepines
Barbiturates
Norepinephrine
Prominent EEG waveform during... Awake with eyes open Awake with eyes closed Stage N1 Non-REM (light sleep) Stage N2 Non-REM (deep sleep) Stage N3 Non-REM (deepest sleep) REM
Note - REM occurs every 90 minutes and increases in duration throughout the night
Beta (highest frequency, lowest amplitude)
Alpha
Theta
Sleep spindles, K complexes
Delta (lowest frequency, highest amplitude)
Beta
Stage of sleep where the following occurs... Bruxism Sleepwalking Night terrors Bedwetting Loss of motor tone Variable pulse and blood pressure Dreaming/Nightmares Penile/clitral erection Memory processing
N2 N3 N3 N3 REM REM REM REM REM
Input to VPLN of thalamus
Spinothalamic
Dorsal column
Medial lemniscus
Note - To primary somatosensory cortex (postcentral gyrus)
Input to VPMN of thalamus
Trigeminal (face sensation)
Gustatory (taste)
Note - To primary somatosensory cortex (postcentral gyrus)
Input to LGN of thalamus
CN II (vision)
Note - To calcarine sulcus
Input to MGN of thalamus
Superior Olive/Inferior Colliculus of Tectum (hearing)
Note - To temporal lobe
Input to VLN of thalamus
Basal ganglia/Cerebellum
Note - To motor cortex (precentral gyrus)
Function of the limbic system - includes... Hippocampus Amygdala Fornix Mamillary bodies Cingulate gyrus
(“5 Fs”)
Feeling Feeding Fleeing Fighting Sex
Mechanism of Schizophrenia/Antipsychotic effects... Mesocortical Mesolimbic Nigrostriatal Tuberoinfundibular
Decreased in schizophrenia - Negative symptoms
Increased in schizophrenia - Positive symptoms
Decreased by antipsychotics - EPS
Decreased by antipsychotics - Hyperprolactinemia
Input and output of the cerebellum
Input:
Contralateral cortex via middle cerebellar peduncle
Ipsilateral proprioceptive information via inferior cerebellar peduncle from spinal cord
Output:
Contralateral cortex via superior cerebellar peduncle
Deep nuclei (lateral to medial)
“Don’t Eat Greasy Foods”
Dentate
Emboliform
Globose
Fastigial
Note - Deep nuclei are the connection between the Purkinje cells and the Superior cerebellar peduncle
Wide-based (truncal) cerebellar gait
Dysarthria
Head tilting
CENTRAL VERMIS (FASTIGIAL) LESION
May also develop Vertigo/Nystagmus from involvement of the Flocculonodular lobe
medial lesion affects the medial structures bilaterally
Basal ganglia direct pathway
Cortical inputs stimulate Striatum (Caudate, Putamen)
Striatum releases GABA inhibiting GPi
GPi stops releasing GABA disinhibitng the Thalamus
Increased movement
Dopamine from SNc binds D1 stimulating this pathway
Note - Motor cortex also directly modulates movement via the pedunculo-pontine nucleus
Basal ganglia indirect pathway
Cortical inputs stimulate the Striatum (Caudate, Putamen)
Striatum releases GABA inhibiting GPe
GPe stops releasing GABA disinhibiting the STN
STN stimulates GPi to inhibit Thalamus
Decreased movement
Dopamine from SNc binds D2 inhibiting this pathway
Treatment of…
High-frequency tremor of sustained posture
Worse with movement
ESSENTIAL TREMOR
Autosomal dominant
Treat with…
Propranolol
Primidone
Lesion resulting in hemiballismus
Contralateral subthalamic nucleus (STN)
Note - Usually from a lacunar stroke
Intracellular eosinophilic inclusions - Composed of a-synuclein
LEWY BODY
Mechanism of neuronal damage in Huntington’s
Presents as caudate atrophy and hydrocephalus ex vacuo
- choreoathetosis
- dementia
- death
Autosomal dominant
CAG repeat
Loss of Ach and GABA in caudate leads to neuronal death via NMDA-R binding and glutamate excitotoxicity
Location of Broca’s area
Left posterior inferior frontal gyrus
Broca’s aphasia - language output deficit. Slow effortful speech that is agrammatic and telegraphic. Comprehension is largely preserved
Location of Wernicke’s area
Left posterior superior temporal gyrus
Wernicke aphasia- speech is preserved but language content is incorrect. Also have impaired comprehension and experience “word salad”, an inability to repeat, normal fluency, and are unaware of their deficits
Can be due to stroke affecting the middle cerebral artery
Transcortical motor aphasia
Broca’s aphasia with intact repetition
Transcortical sensory aphasia
Wernicke’s aphasia with intact repetition
Transcortical mixed aphasia
Global aphasia with intact repetition
Hyperphagia
Hypersexuality
Hyperorality
KLUVER-BUCY SYNDROME
Bilateral Amygdala lesions - Associated with HSV-1 encephalitis which involves the temporal lobe and limbic system
Agraphia
Acalculia
Finger agnosia
L/R disorientation
GERSTMANN SYNDROME
Dominant (L) parietal cortex lesion
Lesion resulting in…
Intention tremor
Loss of balance
Falling towards towards ipsilateral side
Cerebellar hemisphere
Lesion resulting in…
Anterograde amnesia
Bilateral hippocampal
Lesion resulting in…
Eyes looking away from the lesion
Paramedian pontine reticular formation (PPRF)
Lesion resulting in…
Eyes looking towards the lesion
Frontal eye fields
Note - Above Broca’s area
Equation for CPP
MAP - ICP
Regulation of CPP by CO2 and O2
PCO2 directly related to CPP until > 90
O2 indirectly related to CPP only when < 50
Note - Therapeutic hyperventilation (decreased PCO2) results in vasoconstriction/decreased blood flow and thus decreased ICP
Lesion resulting in…
Coma
Reticular activating system (Midbrain)
Upper leg weakness
Upper arm weakness
Defects in higher order visual processing
WATERSHED STROKE
Often due to severe hypotension
Contralateral face/body paralysis
Contralateral face/body sensory loss
Absence of cortical signs (neglect, aphasia, visual field loss)
Note - Embolic phenomenon most often occur in the cortex
LENTICULO-STRIATE LACUNAR STROKE
Arises from ICA/MCA and supplies Striatum/Internal capsule
Note - Lacunae are liquefactive necrosis from Lipohyalinosis/Microadenomas (HTN, DM)
Contralateral U/L limb paralysis
Contralateral proprioception deficits
Ipsilateral hypoglossal deviation
MEDIAL MEDULLARY SYNDROME
Stroke in paramedian branches of anterior spinal artery
Note - Anterior spinal artery arises from between both vertebral arteries
Ipsilateral face pain and temperature loss Contralateral body pain and temperature loss Vomiting Vertigo Nystagmus Dysphagia Decreased gag reflex Hoarseness Ipsilateral Horner's Ataxia Dysmetria
LATERAL MEDULLARY (WALLENBERG) SYNDROME
Posterior inferior cerebellar artery stroke - Nucleus ambiguus (speech/swallow) deficits specific to this syndrome
Note - PICA arises from vertebral
Ipsilateral upper and lower facial paralysis
Ipsilateral face pain and temperature loss
Contralateral body pain and temperature loss
Vomiting
Vertigo
Nystagmus
Decreased lacrimation
Decreased salivation
Decreased taste (anterior tongue)
Ataxia
Dysmetria
LATERAL PONTINE SYNDROME
Anterior inferior cerebellar artery stroke - Upper and lower facial paralysis is specific to this syndrome
Note - AICA arises from beginning of basilar artery
Most common site of Saccular (berry) aneurysm
Note - Associated with ADPKD and Ehlers-Danlos
Junction of ACA with anterior communicating artery
Microaneurysm of lenticulostriate arteries resulting in internal capsule intraparenchymal hemorrhage
Note - Not seen on angiogram
CHARCOT-BOUCHARD ANEURYSM
Chronic hypertension
Mydriasis
Ptosis
“Down and out” eye
POSTERIOR COMMUNICATING ARTERY ANEURYSM
Compression results in CN III palsy
Bitemporal hemianopia
ANTERIOR COMMUNICATING ARTERY ANEURYSM
Compression of optic chiasm - May also be seen with Meningiomas, Pituitary adenomas, and Craniopharyngiomas
Lobar (not basal ganglia, internal capsule) intraparenchymal hemorrhage in elderly patient
Amyloid angiopathy
Bloody or yellow (xanthochromic) spinal tap
SUBARACHNOID HEMORRHAGE
Nimodipine to prevent subsequent vasospasm and ischemic infarct
May also lead to communicating or obstructive hydrocephalus
Regions most vulnerable to ischemia
Note - NCHCT may be normal for first 6-24 hours, but DWI will detect within first hour
Hippocampus (Pyramidal)
Neocortex
Cerebellum (Purkinje)
Watershed zones
Histologic features of ischemic stroke at... 12 - 48 hours 1 - 3 days 3 - 5 days 1 - 2 weeks > 2 weeks
Red neurons Necrosis + Neutrophils Macrophages (Microglia) Reactive gliosis + Angiogenesis Glial scar + Myelin remnants
Note - Slow microglia recruitment due to BBB allows for myelin persistence in CNS decreasing neuronal regeneration
Headache
Seizures
Focal deficits
Associated with…
Pregnancy
OCP
Factor V Leiden
VENOUS SINUS THROMBOSIS
May progress to venous hemorrhage
Anatomy of dural venous sinuses
Note - Superior saggital sinus is the main location of CSF return via arachnoid granulations
Vein of Galen and Inferior saggital sinus form Straight sinus
Straight sinus, Superior saggital sinus, and Occipital sinus drains to Confluence of sinuses
Confluence of sinuses drains to Transverse sinuses
Transverse sinuses drain to Sigmoid sinuses and then internal Jugular
Anatomy of ventricular system
Note - Ependymal cells of choroid plexus make CSF, which is then drained to arachnoid granulations
Lateral ventricle drains to 3rd ventricle via interventricular foramina of Monro
3rd ventricle drains to 4th ventricle via cerebral (Sylvian) aqueduct
4th ventricle drains to subarachnoid space via foramina of Luschka (lateral) and foramen of Magendie (medial)
Normal mental status Headache worse in morning Diplopia (CN VI palsy) Loss of vision based on head position, sneezing Papilledema Elevated opening pressure
Note - Imaging may be normal or show slit ventricles and empty sella
IDIOPATHIC INTRACRANIAL HYPERTENSION
Associated with…
Vitamin A excess
Danazol
Tetracycline
Treat with... Weight loss Acetazolamide Topiramate LPs, Shunt, Optic nerve fenestration
Mechanism of communicating hydrocephalus - leads to increased ICP, papilledema, and herniation
Decreased CSF absorption by arachnoid granulation - may be due to scarring post-meningitis
Mechanism of NPH - communicating hydrocephalus
Expansion of ventricles distort fibers of corona radiata
Note – Does not result in increased subarachnoid space volume
Mechanism of noncommunicating hydrocephalus
Structural blockage of CSF flow... Foramen of Monro colloid cyst Sylvian aqueduct stenosis 4th ventricle obstruction via Chiari II Foramina of Luschka/Magendie via Dandy-Walker
Ventricular enlargement on imaging without triad of communicating hydrocephalus - ICP is normal
EX VACUO VENTRICULOMEGALY
Vertebral level for spinal tap
L3-L5
Spinal cord ends at L1/2 and subarachnoid space ends at S2 - needle should go below spinal cord but above end of subarachnoid space
Tract anatomy responsible for…
Fine touch
Pressure/Vibration
Proprioception
DORSAL COLUMN
1st order neuron (DRG) ascends ipsilaterally
Synapse in Medulla at Nucleus Cuneatus/Gracilis
2nd order neuron decussates in Medulla and ascends contralaterally via Medial Lemniscus
Synapses in VPL of Thalamus
Note - Gracilis (LE) inside, Cuneatus (UE) outside