Starts day 18; Ends day 21

Notochord induces overlying ectoderm to differentiate into neuroectoderm and form neural plate

Neural plate gives rise to neural tube and neural crest cells

Notochord becomes nucleus pulposus of the intervertebral disc in adults

Primary Vesicles

(Embryology)

3 Primary Vesicles:

1) Forebrain (Prosencephalon) >Telencephalon; Diencephalon

2) Midbrain (Mesencephalon) > Mesencephalon

3) Hindbrain (Rhombencephalon) > Metencephalon; Myelencephalon

Secondary Vesicles

(Embryology)

5 Secondary Vesicles:

1) Telencephalon > Cerebral Hemispheres; Lateral Ventricles

2) Diencephalon > Thalamus; 3rd Ventricle

3) Mesencephalon > Midbrain; Aqueduct

4) Metencephalon > Pons and Cerebellum; Upper part of 4th Ventricle

5) Myelencephalon > Medulla; Lower part of 4th Ventricle

Neuroectoderm:

- CNS neurons

- Ependymal cells (inner lining of ventricles, make CSF)

- Oligodendroglia

- Astrocytes

Neural Crest:

- PNS neurons

- Schwann cells

Mesoderm:

- Microglia (like Macrophages, originate from Mesoderm)

Process = Neurpore fail to fuse (4th week) > persistent connection between amniotic cavity and spinal canal

Association = low folic acid intake before conception and during pregnancy

Signs:

- Increased a-fetoprotein (AFP) in amniotic fluid and maternal serum

- Increased AChE in amniotic fluid (confirmatory test; fetal AChE in CSF > across defect > amniotic fluid)

Failure of bony spinal canal to close, but no structural herniation. Dura is intact.

Usually seen at lower vertebral levels

Associated with tuft of hair or skin dimple at level of bony defect

Meninges (but not the spinal cord) herniate through spinal canal defect

Normal AFP

Anencephaly

(Definition)

Malformation of anterior neural tube resulting in no forebrain, open calvarium

("frog-like appearance")

Anencephaly

(Clinical Findings)

Increased AFP

Polyhydramnios

(no swallowing center in brain)

Anencephaly

(Associations)

Maternal Diabetes (Type I)

Maternal folate supplementation decreases risk

Holoprosencephaly

(Definition)

Holoprosencephaly

(Cause)

Holoprosencephaly

(Clinical Findings)

Moderate = Cleft lip/palate

Most severe = Cyclopia

Chiari II

(Arnold-Chiari Malformation)

Significant herniation of cerebellar tonsil and vermis through foramen magnum with aqueductal stenosis and hydrocephalus

Often presents with:

- Lumbosacral myelomeningocele

- Paralysis below defect

Agenesis of cerebellar vermis with cystic enlargement of 4th ventricle (fills enlarged posterior fossa)

Associations:

- Hydrocephalus

- Spina bifida

Syringomyelia

(Clinical Features)

Cystic cavity (syrinx) in spinal cord

(if central canal > hydromyelia)

Crossing anterior spinal commissural fibers typically damaged first > "cape-like" bilateral loss of pain/temperature sensation in upper extremities

(fine touch is preserved)

Most common at C8-T1

Syringomyelia

(Association)

Chiari I Malformation

- > 3-5 mm cerebellar tonsillar ectopia

- Congenital

- Usually asymptomatic in childhood

- Manifests with headaches and cerebellar symptoms

1st and 2nd branchial arches > anterior 2/3

3rd and 4th branchial arches > posterior 1/3

Muscles derived from occipital myotomes

Tongue Innervation

(Taste, Sensation, Motor)

Anterior 2/3

- Sensation CN V3

- Taste CN VII

Posterior 1/3

- Sensation and Taste CN IX

Extreme Posterior

- Sensation and Taste CN X

Motor = CN XII

Taste = CN VII, IX, X (Solitary Nucleus)

Sensation = CN V3, IX, X

Signal-transmitting cells of nervous sytem

Permanent cell = don't divide in adulthood (no progenitor stem cell population)

Signal-relaying cells with dendrites (input), cell bodies, and axons (output)

Nissle substance (stains RER) stain cell bodies and dendrites (RER not in axon)

Axon injured > Wallerian degeneration

(degeneration distal to injury and axon retraction proximally)

Allows for potential regeneration of axon (if in PNS)

Functions:

- Physical support

- Repair

- K+ metabolism

- Removal of excess NT

- Component of blood-brain barrier

- Glycogen fuel reserve buffer

Reactive gliosis in response to neural injury

Marker = GFAP

Derived from neuroectoderm

Function = CNS phagocyte (scavenger cells)

- Tissue damage > differentiate into large phagocytic cells

Origin = Mesoderm

Appearance:

- Not readily discernible in Nissle stains

- Small irregular nuclei

- Relatively little cytoplasm

HIV-infected microglia > fuse > multinucleated giant cells in CNS

Increases conduction velocity of signals transmitted down axons > Saltatory conduction of action potential between nodes of Ranvier (high concentrations of Na+ channels)

Wraps and insulates axons > increases space constant and conduction velocity

CNS = oligodendrocytes

PNS = Schwann cells

Myelinates axons of neurons in the CNS

(each one myelinates many axons)

Predominant glial cell in white matter

Origin = Neuroectoderm

Appearance = "fried egg" on H&E stain

Injured in:

- MS

- PML

- Leukodystrophies

Each cell myelinates only 1 PNS axon (multiple Schwann cells per axon)

Functions:

- Promote axonal regeneration

- Increase conduction velocity via saltatory conduction

Origin = neural crest cells

Destroyed in Guillain-Barre syndrome

Type of Schwannoma

Typically located in internal acoustic meatus (CN VIII)

If bilateral, strongly associated with NF2

Sensory Corpuscles

(Receptors)

Free nerve endings

Meissner corpuscles

Pacinian corpuscles

Merkel discs

Free Nerve Endings

(Description)

C = slow, unmyelinated fibers

A-delta = fast, myelinated fibers

Free Nerve Endings

(Location)

All skin

Epidermis

Some viscera

Free Nerve Endings

(Senses)

Meissner Corpuscles

(Description)

Large, myelinated fibers

Adapt quickly

Meissner Corpuscles

(Location)

Meissner Corpuscles

(Senses)

Dynamic, fine/light touch

Position sense

Pacinian Corpuscles

(Description)

Large, myelinated fibers

Adapt quickly

Pacinian Corpuscles

(Location)

Deep skin layers

Ligaments

Joints

Pacinian Corpuscles

(Senses)

Vibration

Pressure

Merkel Discs

(Description)

Large, myelinated fibers

Adapt slowly

Merkel Discs

(Location)

Basal epidermal layer

Hair follicles

Merkel Discs

(Senses)

Pressure

Deep static touch

(shapes, edges)

Position sense

Peripheral Nerve

(Layers)

Endoneurium = invests single nerve fiber layers

(Inflammatory infiltrate in Guillan-Barre Syndrome)

Perineurium = surrounds a fascicle of nerve fibers; permeability layer

(must be rejoined in microsurgery for limb reattachment)

Epineurium = dense connective tissue that surrounds entire nerve

(fascicles and blood vessels)

Norepinephrine

(Change in Disease)

Increased in anxiety

Decreased in depression

Dopamine

(Change in Disease)

Increased in Huntington disease

Decreased in Parkinson disease

Decreased in Depression

5-HT

(Change in Disease)

Increased in Parkinson disease

Decreased in Anxiety

Decreased in Depression

ACh

(Change in Disease)

Increased in Parkinson disease

Decreased in Alzheimer disease

Decreased in Huntington disease

GABA

(Change in Disease)

Decreased in Anxiety

Decreased in Huntington disease

Norepinephrine

(Location of Synthesis)

Locus ceruleus (pons)

(Stress and panic)

Dopamine

(Location of Synthesis)

Ventral tegmentum and SNc

(midbrain)

5-HT

(Location of Synthesis)

Raphe nucleus

(pons, medulla, midbrain)

ACh

(Location of Synthesis)

GABA

(Location of Synthesis)

Nucleus accumbens

(Nucleus accumbens + Septal nucleus = reward center; pleasure; addiction; fear)

Blood-Brain Barrier

(Structures)

- Tight junctions between nonfenestrated capillary endothelial cells

- Basement membrane

- Astrocyte foot processes

- Hypothalamic inputs and outputs permeate the BBB

Blood-Brain Barrier

(Crossing)

Glucose + Amino Acids cross slowly by carrier-mediated transport

Nonpolar/Lipid-soluble substances cross rapidly via diffusion

Prevents:

- Bacterial infection spreading into CNS

- Drug delivery to brain

Blood-Brain Barrier

(Regions of Crossing)

- Blood-brain Barrier

- Blood-testis Barrier

- Maternal-fetal blood Barrier of Placenta

Blood-Brain Barrier

(Pathology)

Hypothalamus

(Functions)

TAN HATS

- Thirst and water balance

- Adenohypophysis control (regulates anterior pituitary)

- Neurohypophysis releases hormones produced in hypothalamus

- Hunger

- Autonomic regulation

- Temperature regulation

- Sexual urges

Hypothalamus

(Inputs)

Areas not protected by BBB

OVLT (Organum Vasculosum of the Lamina Terminalis) = senses change in osmolarity

Area Postrema = response to emetics

Lateral Area

(Hypothalamus)

Hunger

Destruction > anorexia; failure to thrive (infants)

[if you zap your lateral nucleus, you shrink laterally]

Inhibited by Leptin

Ventromedial Area

(Hypothalamus)

Satiety

Destruction (craniopharyngioma) > hyperphagia

[If you zap your ventromedial nucleus, you grow ventrally and medially]

Stimulated by Leptin

Cooling, parasympathetic

Anterior nucleus = cool off (cooling, pArasympathetic)

A/C = Anterior Cooling

Heating, sympathetic

Posterior nucleus = get fired up (heating, sympathetic)

If you zap your posterior hypothalamus, you become a poikilotherm (cold-blooded, like a snake)

Suprachiasmatic Nucleus

(Hypothalamus)

Circadian rhythm

You need sleep to be charismatic

Circadian rhythm controls nocturnal release of:

- ACTH

- Prolactin

- Melatonin

- NE

Light > Suprachiasmatic Nucleus > NE release > pineal gland > melatonin

REM (25%)

- Extraocular movements due to PPRF (paramedian pontine reticular formation/conjugate gaze center)

- Sleep occurs every 90 minutes

- Duration increases through the night

non-REM (75%)

- Stage N1 (5%)

- Stage N2 (45%)

- Stage N3 (25%)

Alcohol

Benzodiazepines

Barbiturates

Aging

(Binging, Benzos, Barbiturates, and Balding)

NE also decreases REM sleep

Bedwetting

(Treatment)

Oral Desmopressin Acetate (DDAVP) = mimics ADH

Preferred over Imipramine (adverse effects)

Night Terrors and Sleepwalking

(Treatment)

Sleep Stages: Awake

(Description)

Sleep Stages: Stage N1

(Description)

Sleep Stages: Stage N2

(Description)

Sleep Stages: Stage N3

(Description)

Deepest non-REM sleep (slow-wave sleep)

When sleepwalking, night terrors, and bedwetting occur

Sleep Stages: REM Sleep

(Description)

- Loss of motor tone

- Increased brain O2 use

- Increased and variable pulse and BP

When dreaming and penile/clitoral tumescence occur

may serve a memory processing function

Sleep Stages: Awake

(EGG Waveform)

Eyes open = Beta (highest frequency; lowest amplitude)

Eyes closed = Alpha

Sleep Stages: Stage N1

(EGG Waveform)

Sleep Stages: Stage N2

(EGG Waveform)

Sleep Stages: Stage N3

(EGG Waveform)

Sleep Stages: REM Sleep

(EGG Waveform)

At night, BATS Drink Blood

- Awake (eyes open) = Beta

- Awake (eyes closed) = Alpha

- Stage N1 = Theta

- Stage N2 = Sleep spindles and K complexes

- Stage N3 = Delta

- REM Sleep = Beta

Posterior Pituitary

(Neurohypophysis)

Thalamus: VPL

(Input)

Spinothalamic

Dorsal columns/Medial lemniscus

Thalamus: VPM

(Input)

Thalamus: LGN

(Input)

Thalamus: MGN

(Input)

Superior Olive

Inferior Colliculus of Tectum

Thalamus: VL

(Input)

Basal ganglia

Cerebellum

Thalamus: VPL

(Info)

Pain and temperature

Pressure, touch, vibration, and proprioception

Thalamus: VPM

(Info)

Face sensation and taste

Makeup goes on the face (VPM)

Thalamus: LGN

(Info)

Vision

Lateral = Light (LGN)

Thalamus: MGN

(Info)

Hearing

Medial = Music (MGN)

Thalamus: VL

(Info)

Thalamus: VPL

(Destination)

Thalamus: VPM

(Destination)

Thalamus: LGN

(Destination)

Thalamus: MGN

(Destination)

Thalamus: VL

(Destination)

Limbic System

(Function)

Collection of neural structures involved in:

- Emotion

- Long-term memory

- Olfaction

- Behavior modulation

- Autonomic nervous system function

The famous 5 F'S:

Feeding; Fleeing; Fighting; Feeling; Sex

Limbic System

(Structures)

Hippocampus

Amygdala

Fornix

Mammillary bodies

Cingulate gyrus

Cerebellum

(Function)

Modulates movement

Aids in coordination and balance

Cerebellum

(Input)

Middle cerebellar peduncle = Contralateral cortex

Inferior cerebellar peduncle = Spinal cord > Ipsilateral proprioceptive information

Input nerves = Climbing and Mossy fibers

Cerebellum

(Output)

Contralateral cortex = modulate movement

(Nerves = Purkinje cells > deep nuclei of cerebellum > Superior cerebellar peduncle > Contralateral Cortex)

Deep Nuclei: (lateral > medial)

- Dentate

- Emboliform

- Globose

- Fastigial

(Don't Eat Greasy Foods)

Cerebellum

(Lateral Lesions)

Voluntary movement of extremities

Injury > Propensity to fall toward injured (ipsilateral) side

Cerebellum

(Medial Lesions)

Lesions involving midline structures (Vermal Cortex; Fastigial Nuclei) and/or the Flocculonodular Lobe

Results in:

- Truncal ataxia

- Nystagmus

- Head tilting

- Wide-based (cerebellar) gait

Bilateral motor deficits affecting axial and proximal limb musculature

Basal Ganglia

(Function)

Important in voluntary movements and making postural adjustments

Receives cortical input > provides negative feedback to cortex > modulates movement

Basal Ganglia

(Components)

Globus Pallidus (externus and internus)

Substantia Nigra pars compacta (SNc)

Subthalamic Nucleus (STN)

Striatum (Putamen [Motor] + Caudate [Cognitive])

Basal Ganglia

(Direct Pathway)

Basal Ganglia

(Indirect Pathway)

Degenerative disorder associated with:

1) Lewy bodies

(composed of a-synuclein; intracellular eosinophilic inclusion)

2) Loss of Dopaminergic neurons of the SNc

(depigmentation)

Parkinson TRAPS your body

- Tremor (at rest; pill-rolling)

- Rigidity (cogwheel)

- Akinesia (or bradykinesia)

- Postural instability

- Shuffling gait

Huntington Disease

(Cause)

Autosomal Dominant trinucleotide repeat (CAG) disorder on chromosome 4

Decrease in levels of GABA and ACh in brain

(Caudate loses ACh and GABA)

Neuronal death via NMDA-R binding and Glutamate toxicity

Huntington Disease

(Characteristics)

1) Symptoms manifest between ages 20 and 50

2)  Choreiform movements

3) Aggression

4) Depression

5) Dementia

6) Atrophy of caudate nuclei on imaging

1) Hemiballismus

2) Chorea

3) Athetosis

4) Myoclonus

5) Dystonia

6) Essential (Postural) Tremor

7) Resting Tremor

8) Intention Tremor

Hemiballismus

(Presentation)

Hemiballismus

(Characteristic Lesion)

Contralateral Subthalamic Nucleus

(e.g., Lacunar stroke)

Hemiballismus

(Notes)

"Half-of-body ballistic"

Contralateral lesion

Chorea

(Presentation)

Chorea

(Characteristic Lesion)

Basal Ganglia

(e.g., Huntington)

Chorea

(Notes)

Athetosis

(Presentation)

Slow, writhing movements

Especially seen in fingers

Athetosis

(Characteristic Lesion)

Basal Ganglia

(e.g., Huntington)

Athetosis

(Notes)

Myoclonus

(Presentation)

Myoclonus

(Notes)

Jerks; hiccups

Common in metabolic abnormalities such as renal and liver failure

Dystonia

(Presentation)

Dystonia

(Notes)

Writer's cramp

Blepharospasm

(sustained eyelid twitch)

Essential (Postural) Tremor

(Presentation)

Action tremor

Exacerbated by holding posture/limb position

Essential (Postural) Tremor

(Notes)

Genetic predisposition

Patients often self-medicate with EtOH > decreases tremor amplitude

Treatment = B-blockers; Primidone

Resting Tremor

(Presentation)

Uncontrolled movement of distal appendages

(most noticable in hands)

Tremor alleviated by intentional movement

Resting Tremor

(Characteristic Lesion)

Resting Tremor

(Notes)

Occurs at rest

("pill-rolling tremor" of Parkinson)

Intention Tremor

(Presentation)

Intention Tremor

(Characteristic Lesion)

Broca Area

(Brain Location; Function)

Motor speech

Dominant hemisphere

Inferior, posterior part of Frontal cortex

Principal Motor Area

(Brain Location)

Wernicke Area

(Brain Location; Function)

Associative auditory cortex

Dominant Hemisphere

Posterior superior portion of Temporal lobe

Principal Visual Cortex

(Brain Location)

Primary Auditory Cortex

(Brain Location)

Medial superior portion of Temporal lobe

(near Sylvian fissure)

Topographical representation of motor and sensory areas in the cerebral cortex.

Distorted appearance due to certain body regions being more richly innervated > higher cortical representation

HAL lives in your brain

(Head, Arm Leg = lateral to medial)

Common brain lesions:

Amygdala (bilateral)

Kluver-Bucy Syndrome

- Hyperorality

- Hypersexuality

- Disinhibited behavior

Association = HSV-1

(Miley Cyrus Syndrome)

Common brain lesions:

Frontal Lobe

Disinhibition and deficits in concentration, orientation, and judgment

May have reemergence of primitive reflexes

Common brain lesions:

Spatial Neglect Syndrome

(Agnosia of the contralateral side of the world)

Gerstmann Syndrome

(Agraphia, Acalculia, Finger Agnosia, and Left-right disorientation)

- Can't count, can't write, can't turn to the right

Common brain lesions:

REduced elvels of arousal and wakefulness

(e.g., Coma)

Common brain lesions:

Wernicke-Korsakoff Syndrome

Symptoms:

1) Confusion

2) Ophthalmoplegia

3) Ataxia

4) Memory loss (anterograde and retrograde)

5) Confabulation

6) Personality changes

Association = Thiamine (B1) deficiency due to excessive EtOH use

(Can be precipitated by giving glucose with B1 to a B1-deficient patient)

Wernicke problems come in a CAN of beer

(Confusion, Ataxia, Nystagmus)

Common brain lesions:

May result in:

- Tremor at rest

- Chorea

- Athetosis

Association = Parkinson Disease

Common brain lesions:

Truncal ataxia

Dysarthria

(Vermis is centrally located = affects central body)

Common brain lesions:

Common brain lesions:

Anterograde amnesia

(inability to make new memories)

Common brain lesions:

Common brain lesions:

Central Pontine Myelinolysis

(Cause)

Massive axonal demyelination in pontine white matter tracts secondary to osmotic forces and edema

Commonly iatrogenic

(overly rapid correction of hyponatremia)

Correcting serum Na+ too fast:

1) From low to high, your pons will die (CPM)

2) From high to low, your brain will blow (cerebral edema/herniation)

Central Pontine Myelinolysis

(Symptoms)

1) Acute paralysis

2) Dysarthria

3) Dysphagia

4) Diplopia

5) Loss of consciousness

Can cause "locked-in syndrome"

(TERRIFYING!!!)

Central Pontine Myelinolysis

(Imaging)

Aphasia = Higher-order inability to speak

(language deficit)

Dysarthria = motor inability to speak

(movement deficit)

Nonfluent aphasia with intact comprehension

Broca area = Inferior frontal gyrus of frontal lobe

Broca Broken Boca

Fluent aphasia with impaired comprehension and repetition

Wernicke area = Superior temporal gyrus of temporal lobe

Wernicke is Wordy but makes no sense

Wernicke = "What?"

Nonfluent aphasia with impaired comprehension

Both Broca and Wernicke areas affected

Poor repetition but fluent speech, intact comprehension

Can be caused by damage to left superior temporal lobe and/or left supramarginal gyrus

(Can't repeat phrases such as "No ifs, ands, or buts")

Anterior Cerebral Artery

(Distribution)

Middle Cerebral Artery

(Distribution)

Posterior Cerebral Artery

(Distribution)

Between:

- Anterior Cerebral / Middle Cerebral

- Posterior Cerebral / Middle Cerebral

Damage in severe hypotension:

- Upper leg/arm weakness

- Defects in higher-order visual processing

Brain perfusion relies on tight autoregulation. Primarily driven by PCO2

(also modulates perfusion in severe hypoxia)

Treatment for Cerebral Edema (Stroke/Trauma):

Therapeutic hyperventilation > decreased PCO2 > vasoconstriction > decreased cerebral perfusion > decreased intracranial pressure

Regulation of Cerebral Perfusion

(Hypoxemia)

Regulation of Cerebral Perfusion

(PCO2)

Strokes:

MCA

(Area of Lesion)

Motor Cortex = upper limb and face

Sensory Cortex = upper limb and face

Temporal lobe = Wernicke area

Frontal lobe = Broca area

Strokes:

ACA

(Area of Lesion)

Motor Cortex = lower limb

Sensory Cortex = lower limb

Strokes:

Lenticulostriate Artery

(Area of Lesion)

Striatum

Internal capsule

Strokes:

ASA

(Area of Lesion)

Lateral corticospinal tract

Medial lemniscus

Caudal medulla = Hypoglossal nerve

Strokes:

PICA

(Area of Lesion)

Lateral Medulla:

1) Vestibular nuclei

2) Lateral spinothalamic tract

3) Spinal trigeminal nucleus

4) Nucleus Ambiguus

5) Sympathetic fibers

6) Ifferior cerebellar peduncle

Strokes:

AICA

(Area of Lesion)

Lateral Pons = cranial nerve nuclei

1) Vestibular nuclei

2) Facial nucleus

3) Spinal trigeminal nucleus

4) Cochlear nuclei

5) Sympathetic fibers

Strokes:

PCA

(Area of Lesion)

Occipital cortex

Visual cortex

Strokes:

Basilar Artery

(Area of Lesion)

1) Pons

2) Medulla

3) Lower midbrain

4) Cortispinal and Corticobulbar tracts

5) Ocular cranial nerve nuclei

6) Paramedian Pontine Reticular Formation (PPRF)

Strokes:

ACom

(Area of Lesion)

Most common lesion in aneurysm > leads to stroke

Saccular (berry) aneurysm > impinges cranial nerves

Strokes:

PCom

(Area of Lesion)

Strokes:

MCA

(Symptoms)

Contralateral paralysis = upper limb and face

Contralateral loss of sensation = upper/lower limbs and face

Aphasia if in dominant (usually left) hemisphere

Hemineglect if lesion affects nondominant (usually right) side

Strokes:

ACA

(Symptoms)

Contralateral paralysis = lower limb

Contralateral loss of sensation = lower limb

Strokes:

Lenticulostriate Artery

(Symptoms)

Strokes:

ASA

(Symptoms)

Medial Medullary Syndrome

(Commonly bilateral; caused by infarct of Paramedian branches of ASA and Vertebral arteries)

1) Contralateral hemiparesis = upper and lower limbs

2) Decreased contralateral proprioception

3) Ipsilateral hypoglossal dysfunction

(tongue deviates ipsilaterally)

Strokes:

PICA

(Symptoms)

Lateral Medullary (Wallenberg) Syndrome

1) Vomiting

2) Vertigo

3) Nystagmus

4) Decreased pain and temperatuer sensation from ipsilateral face and contralateral body

5) Dysphagia, Hoarseness, Decreased Gag Reflex

(Nucleus Ambiguss: Don't pick a horse that can't eat)

6) Ipsilateral Horner syndrome

7) Ataxia

8) Dysmetria

Strokes:

AICA

(Symptoms)

Lateral Pontine Syndrome

1) Vomiting, Vertigo, Nystagmus

2) Facial Nucleus = Paralysis of face, Decreased lacrimation/salivation, Decreased taste from anterior 2/3 of tongue, Decreased corneal reflex

(Facial droop means AICA's pooped)

3) Decreased pain and temperature sensation of face

4) Ipsilateral decreased hearing

5) Ipsilateral Horner syndrome

6) Ataxia

7) Dysmetria

Strokes:

PCA

(Symptoms)

Strokes:

Basilar Artery

(Symptoms)

Locked-In Syndrome

1) Preserved consciousness and blinking

2) Quadriplegia

3) Loss of voluntary facial, mouth, and tongue mvoements

Strokes:

ACom

(Symptoms)

Visual field defects

Lesions are typically aneurysms, not strokes

Strokes:

PCom

(Symptoms)

CN 3 palsy = eye is "down and out" with ptosis and pupil dilation

Lesions are typically aneurysms, not strokes

Berry Aneurysm

(Location)

Occurs at the bifurcations in the circle of Willis

Most common site = Junction of ACom and ACA

Berry Aneurysm

(Consequences)

Rupture (most common complication) causes:

- Subarachnoid hemorrhage

(WHoL)

- Hemorrhagic stroke

Compression of optic chiasm > Bitemporal Hemianopia

Berry Aneurysm

(Associations and Risk Factors)

1) ADPKD

2) Ehlers-Danlos Syndrome

3) Marfan Syndrome

4) Advanced age

5) HTN

6) Smoking

7) Race (increase risk in blacks)

Associated with chronic HTN

Affects small vessels

(e.g., Basal Gangle and Thalamus)

Neuropathic pain due to Thalamic lesions

Symptoms = initial sensation of numbness and tingling followed in weeks to months by allodynia (ordinarily painless stimuli cause pain) and dysaesthesia

Occurs in 10% of stroke patients

Epidural Hematoma

(Cause)

Epidural Hematoma

(Symptoms)

Lucid interval

Rapid expansion under systemic arterial pressure leads to:

1) Transtentorial herniation

2) CN 3 palsy

Epidural Hematoma

(Imaging)

CT shows biconvex (lentiform), hyperdense blood collection that does not cross suture lines

Can cross falx and tentorium

Subdural Hematoma

(Cause)

Rupture of bridging veins

Seen in:

- Elderly

- Alcoholics

- Blunt trauma

- Shaken baby

Predisposing Factors:

- Brain atrophy

- Shaking

- Whiplash

Subdural Hematoma

(Imaging)

Crescent-shaped hemorrhage that crosses suture lines

Can NOT cross falx and tentorium

Subarachnoid Hemorrhage

(Cause)

Subarachnoid Hemorrhage

(Symptoms)

Rapid time course

WHOML

("worst headache of my life")

Bloody or yellow (xanthochromic) spinal tap

Risk of vasospasm 2-3 days later due to blood breakdown (not visisble on CT; Treatment = nimodipine) and rebleed (visible on CT)

Subarachnoid Hemorrhage

(Imaging)

Intraparenchymal (Hypertensive) Hemorrhage

(Cause)

Systemic HTN

Also seen in:

- Amyloid angiopathy

- Vasculitis

- Neoplasm

Intraparenchymal (Hypertensive) Hemorrhage

(Location)

Intraparenchymal (Hypertensive) Hemorrhage

(Imaging)

Ischemic Brain Disease/Stroke

(Most vulnerable areas)

Hippocampus

(ischemic hypoxia = hypocampus most vulnerable)

Neocortex

Cerebellum

Watershed areas

Ischemic Brain Disease/Stroke

(Imaging)

Bright on diffusion-weighted MRI in 3-30 minutes

(highest sensitivity for early ischemia

Dark abnormality on noncontrast CT in ~ 12-24 hrs

(used more often because faster/easier test)

Absence of bright areas on noncontrast CT highly accurate to exclude hemorrhage

(hemorrhage = contraindication for tPA)

Ischemic Brain Disease/Stroke

(Time Course and Histologic Features)

Irreversible neuronal injury begins after 5 minutes of hypoxia

12-48 Hours = Red neurons

24-72 Hours = Necrosis + Neutrophils

3-5 Days = Macrophages

1-2 Weeks = Reactive gliosis + Vascular proliferation

> 2 Weeks = Glial scar

Intracerebral bleeding

Often due to:

- HTN

- Anticoagulation

- Cancer (abnormal vessels bleed)

May be secondary to ischemic stroke followed by reperfusion (increased vessel fragility)

Most common site = Basal Ganglia

Ischemic Stroke

(Cause)

Acute blockage of vessels > disruption of blood flow > ischemia

Results in liquefactive necrosis

Ischemic Stroke

(Types)

Thrombotic = due to a clot forming directly at the site of infarction (commonly MCA), usually over an atherosclerotic plaque

Embolic = an embolus from another part of the body obstructs a vessel; can affect multiple vascular territories. Often cardioembolic

Hypoxic = due to hypoperfusion or hypoxemia; common during cardiovascular surgeries; tends to affect watershed areas

Ischemic Stroke

(Treatment)

tPA

(if within 3-4.5 hours of onset and no hemorrhage/risk of hemorrhage)

Reduce risk with medical therapy:

- Aspirin; Clopidogrel

- Optimum control of BP, Blood sugars, and Lipids

- Treat conditions that increase risk (afib)

Brief, reversible episode of focal neurologic dysfunction last < 24 hours without acute infarction (negative MRI)

Majority resolve in < 15 minutes

Deficits due to focal ischemia

Large venous channels that run through the dura. Drain blood from cerebral veins and receive CSF from arachnoid granulations

Empty into IJV

Sinuses:

- Superior Sagittal Sinus (main location of CSF return)

- Inferior Sagittal Sinus

- Great Cerebral Vein of Galen

- Straight Sinus

- Confluence of the Sinuses

- Occipital Sinus

- Transverse Sinus

- Sigmoid Sinus

- Cavernous SInus

- Sphenoparietal sinus

- Superior Ophthalmic vein

KNOW WHERE ALL OF THESE ARE! (pg 463)

Lateral Ventricle > 3rd Ventricle via right and left Interventricular Foramina of Monro

3rd Ventricle > 4th Ventricle via Cerebral Aqueduct (of Sylvius)

4th Ventricle > Subarachnoid space via:

- Foramina of Luschka = Lateral

- Foramen of Magendie = Medial

Made by ependymal cells of choroid plexus

Reabsorbed by arachnoid granulations

Drains into dural venous sinuses

Communicating Hydrocephalus

Normal Pressure Hydrocephalus

Hydrocephalus ex Vacuo

Decreased CSF absorption by arachnoid granulations > increased intracranial pressure

- Papilledema

- Herniation

Possible cause = arachnoid scarring post-meningitis

Does not result in increased subarachnoid space volume

Expansion of ventricles distorts the fibers of the Corona Radiata > clinical triad of Wet, Wobbly, and Wacky

- Urinary Incontinence

- Ataxia

- Cognitive Dysfunction (sometimes reversible)

Appearance of increased CSF in atrophy

(Alzheimer disease; advanced HIV; Pick disease)

Intracranial pressure is normal; NO triad!

Apparent increase in CSF in imaging is actually due to decreased neural tissue (atrophy)

Cause = structural blockage of CSF circulation within the ventricular system

(Stenosis of the aqueduct of Sylvius)

31 total:

- 8 cervical

- 12 thoracic

- 5 lumbar

- 5 sacral

- 1 coccygeal

C1-C7 exit above the corresponding vertebra; all other exit below

Nucleus pulposus (soft central disc) herniates through annulus fibrosus (outer ring)

Usually occurs posterolaterally at L4-L5 or L5-S1

Adults = extends to lower border of L1-L2 vertebrae

Subarachnoid space (contains CSF) extends to lower border of S2 vertebra

Lumbar Puncture = between L3-L4 or L4-L5

(level of Cauda Equina)

Goal of LP is to obtain sample of CSF without damaging spinal cord

(To keep the cord alive, keep the needle between L3 and L5)

Lateral Corticospinal Tract

(voluntary motor)

- Lateral = Legs

- Medial = Arms

Anterior Corticospinal Tract

(voluntary motor - only 15%; crosses later down spine)

Dorsal Column

(Pressure, Vibration, Touch, Proprioception)

Fasciculus Gracilis = Medial; Lower body, legs

Fasciculus Cuneatus = Lateral; Upper body, arms

(Think of how someone stands with their arms out laterally)

Lateral Spinothalamic Tract

(Pain, Temperature)

Lateral = Legs

Medial = Arms

Anterior Spinothalamic Tract

(Crude touch, Pressure)

Sympathetic fibers

(T1 - L2/L3)

Dorsal Column

(Function)

Ascending:

- Pressure

- Vibration

- Fine touch

- Proprioception

Dorsal Column

(1st Order Neuron)

Dorsal Column

(Synapse 1)

Ipsilateral nucleus Cuneatus or Gracilis

(Medulla)

Dorsal Column

(2nd Order Neuron)

Dorsal Column

(Synapse 2)

VPL

(Thalamus)

Dorsal Column

(3rd Order Neuron)

Spinothalamic Tract

(Function)

Ascending

Lateral = Pain, Temperature

Anterior = Crude touch, Pressure

Spinothalamic Tract

(1st Order Neuron)

Spinothalamic Tract

(Synapse 1)

Ipsilateral gray matter

(spinal cord)

Spinothalamic Tract

(2nd Order Neuron)

Spinothalamic Tract

(Synapse 2)

VPL

(Thalamus)

Spinothalamic Tract

(3rd Order Neuron)

Lateral Corticospinal Tract

(Function)

Descending

Voluntary movement of contralateral limbs

Lateral Corticospinal Tract

(1st Order Neuron)

UMN:

Cell body in Primary Motor Cortex > descends ipsilaterally (through Internal Capsule)

Most fibers decussate at caudal Medulla (Pyramidal decussation) > descends contralaterally

Lateral Corticospinal Tract

(Synapse 1)

Cell body of anterior horn

(spinal cord)

Lateral Corticospinal Tract

(2nd Order Neuron)

Lateral Corticospinal Tract

(Synapse 2)

1) Weakness

2) Increased reflexes

3) Increased tone

4) Babinski (normal in infants)

5) Spastic paralysis

6) Clasp knife spasticity

Upper MN = everything up (tone, DTRs, toes)

1) Weakness

2) Atrophy

3) Fasciculations

4) Decreased reflexes

5) Decreased tone

6) Flaccid paralysis

Lower MN = everything lowered (muscle mass, tone, DTRs, toes)

Spinal Cord Lesions:

Poliomyelitis

(Area Affected)

Spinal Cord Lesions:

Multiple Sclerosis

(Area Affected)

Spinal Cord Lesions:

Amyotrophic Lateral Sclerosis

(Area Affected)

Spinal Cord Lesions:

Complete occlusion of anterior spinal artery

(Area Affected)

Spinal Cord Lesions:

Tabes Dorsalis

(Area Affected)

Spinal Cord Lesions:

Spinal Muscular Atrophy

(Area Affected)

Spinal Cord Lesions:

Syringomyelia

(Area Affected)

Central Canal > expands to damage tracts

(especially Anterior White Commissure of Spinothalamic tract)

Spinal Cord Lesions:

Vitamin B12 Deficiency

(Area Affected)

Dorsal Columns

Lateral corticospinal tracts

Spinocerebellar tracts

Spinal Cord Lesions:

Vitamin E Deficiency

(Area Affected)

Dorsal columns

Lateral corticospinal tracts

Spinocerebellar tracts

Spinal Cord Lesions:

Poliomyelitis

(Characteristics)

LMN lesions only

(due to destruction of anterior horns)

Flaccid paralysis

Spinal Cord Lesions:

Spinal Muscular Atroph

(Characteristics)

Also called Werdnig-Hoffmann disease

LMN lesions only

(due to destruction of Anterior horns)

Flaccid paralysis

Spinal Cord Lesions:

Multiple Sclerosis

(Characteristics)

Due to demyelination

Randon and asymmetric lesions

(mostly white matter of cervical region)

Scanning speech; Intention tremor; Nystagmus

Spinal Cord Lesions:

Amyotrophic Lateral Sclerosis

(Characteristics)

ALS; also called Lou Gehrig Disease

Combined UMN and LMN deficits with no sensory, cognitive, or oculomotor deficits

(Stephen Hawking = well-known patient who highlights lack of cognitive deficit)

Both UMN and LMN signs

(Commonly presents as fasciculations with eventual atrophy and weakness of hands)

Can be caused by defect in Superoxide Dismutase 1

Fatal; Riluzole modestly increases survival by decreased presynaptic glutamate release

(For Lou Gehrig disease, give rilouzole)

Spinal Cord Lesions:

Complete occlusion of ASA

(Characteristics)

Upper thoracic ASA territory is a watershed area

(Artery of Adamkiewicz supplies ASA below T8)

Spares dorsal columns and Lissauer tract

Spinal Cord Lesions:

Tabes Dorsalis

(Characteristics)

Cause = Tertiary Syphilis

(demyelination of Dorsal Columns and Roots)

Impaired sensation and proprioceptions

Progressive sensory ataxia

(inability to sense/feel the legs > poor coordination)

Associations:

- Charcot joints

- Shooting pain

- Argyll Robertson pupils 

(small bilateral pupils that further constrict to accomodation and convergence, but not to light)

Exam shows absence of DTFs and positive Romberg

Spinal Cord Lesions:

Syringomyelia

(Characteristics)

Syrinx expands > damages Anterior White Commissure of Spinothalamic tract

(2nd Order Neurons)

- Can expand and affect other tracts

Bilateral loss of Pain and Temperature

(usually C8-T1)

Seen with Chiari I malformation

Spinal Cord Lesions:

Vitamin B12 Deficiency

(Characteristics)

Subacute combined degeneration

(demyelination of Dorsal Columns, Lateral Corticospinal tracts, and Spinocerebellar tracts)

Ataxic gait

Paresthesia

Impaired position and vibration sense

Spinal Cord Lesions:

Vitamin E Deficiency

(Characteristics)

Subacute combined degeneration

(demyelination of Dorsal Columns, Lateral Corticospinal tracts, and Spinocerebellar tracts)

Ataxic gait

Paresthesia

Impaired position and vibration sense

Poliomyelitis

(Cause)

Poliovirus

(fecal-oral transmission)

Replicates in oropharynx and small intestine > hematogenous spread to CNS

Infection > destruction of cells in Anterior Horn of spinal cord

(LMN death)

Poliomyelitis

(Symptoms)

LMN Lesion Signs

- Weakness

- Hypotonia

- Flaccid paralysis

- Fasciculations

- Hyporeflexia

- Muscle atrophy

Signs of infection

- Malaise

- Headache

- Fever

- Nausea

etc.

Poliomyelitis

(Findings)

CSF with increased WBCs and slight increase of protein

(no change in CSF glucose)

Virus recovered from stool or throat

Also called Werdnig-Hoffmann Disease

Congenital degeneration of Anterior Horns of spinal cord

(LMN lesion; Autosomal Recessive)

"Floppy baby"

Marked hypotonie

Tongue fasciculations

Infantile type = median age of death of 7 months

Friedreich Ataxia

(Cause)

Autosomal Recessive

Trinucleotide repeat disorder (GAA) on chromosome 9 in gene that encodes Frataxin

(iron-binding protein)

Causes impairment in mitochondrial functioning > degeneration of multiple spinal cord tracts

Friedreich Ataxia

(Presentation)

1) Muscle weakness

2) Loss of DTRs, vibratory sense, and proprioception

3) Staggering gait

4) Frequent falling

5) Nystagmus

6) Dysarthria

7) Pes cavus

8) Hammer toes

9) Hypertrophic cardiomyopathy (cause of death)

10) Presents in childhood with kyphoscoliosis

Brown-Sequard Syndrome

(Cause)

Brown-Sequard Syndrome

(Presentation)

Lesion above T1 = patient may present with Horner syndrome

(damage to Oculosympathetic pathway)

Ipsilateral:

1) UMN signs below level of lesion

(Corticospinal tract damage)

2) Loss of tactile, vibration, proprioception sense 1-2 levels below lesion

(Dorsal Column damage)

3) Loss of all sensation at level of lesion

4) LMN signs (flaccid paralysis) at level of lesion

Contralateral:

1) Loss of pain and temperature below level of the lesion

(Spinothalamic tract damage)

Sympathectomy of face

PAM is horny

- Ptosis (eyelid droop; Superior tarsal muscle)

- Anhidrosis (absence of sweating)

- Miosis (pupil constriction)

Association = lesion of spinal cord above T1

- Pancoast tumor

- Brown-Sequard syndrome (cord hemisection)

- Late-stage Synringomyelia

Horner Syndrome

(Pathway)

3-neuron Oculosympathetic pathway

Projects from hypothalamus > Intermediolateral column of the spinal cord > Superior Cervical (sympathetic) Ganglion > Pupil; Smooth muscle of eyelid; Sweat glands of the forehead/face

Dermatome of:

Posterior half of skull cap

Dermatome of:

Dermatome of:

Dermatome of:

T4

(T4 at the teat pore)

Dermatome of:

Dermatome of:

T10

(T10 and the belly butten)

Important for early appendicitis pain referral

Dermatome of:

L1

(L1 at the IL)

Dermatome of:

L4

(Down on alL 4's)

Dermatome of:

S2, S3, S4

(S2, 3, 4 keeps the penis off the floor)

Erection and sensation of penile and anal zones

Phrenic nerve

(referred pain)

Dermatome of:

Dermatome of:

Dermatome of:

Dermatome of:

Biceps

(Clinical Reflexes)

Triceps

(Clinical Reflexes)

Patella

(Clinical Reflexes)

Achilles

(Clinical Reflexes)

Clinical Reflexes

(Mnemonic)

Count up in order:

S1, 2 - buckle my shoe (Achilles)

L3, 4 - kick the door (Patellar)

C5, 6 - pick up sticks (Biceps)

C7, 8 - lay them straight (Triceps)

Additional:

 L1, L2 - testicles move (Cremaster)

S3, S4 - winks galore (Anal Wink)

Present in healthy infant, but absent in neurologically intact adult

Normally disappear within 1st year of life

(inhibited by mature/developing frontal lobe)

Reemerge in adults following frontal lobe lesions

(loss of inhibition)

Moro Reflex

(Primitive Reflexes)

"Hang on for life" reflex

Abduct/extend limbs when startled, and then draw together

Rooting Reflex

(Primitive Reflexes)

Movement of head toward one side if cheek or mouth is stroked

(nipple seeking)

Sucking Reflex

(Primitive Reflexes)

Palmar Reflex

(Primitive Reflexes)

Plantar Reflex

(Primitive Reflexes)

Dorsiflexion of large toe and fanning of other toes with plantar stimulation

Babinski sign = presence of this reflex in an adult

(signifies UMN lesion)

Galant Reflex

(Primitive Reflexes)

3, 6, 12

3(x2) = 6(x2) = 12

Motor = Medial

Melatonin secretion

Circadian rhythms