Hippocampus

Neocortex

Cerebellum

Watershed areas (area between ACA and MCA)

Red neurons

(eosinophilic cytoplasm, pyknotic nucleus, loss of Nissl substance)

pyknotic nucleus = small and deeply basophilic

Reactive gliosis

Vascular proliferation

Autosomal Dominant (NF1 gene; 17) PNS tumor characterized by:

neurofibromas

optic nerve gliomas

Lisch Nodules

cafe au lait spots

Autosomal Dominant nervous system tumor syndrome characterized by:

bilateral CNVIII schwannomas

multiple meningiomas

Sturge-Weber Syndrome

(encephalotrigeminal angiomatosis)

Rare congenital neurocutaneous disorder characterized by:

cutaneous facial angiomas (involving V₁ and V₂)

leptomeningial angiomatosis

mental retardation

seizures

hemiplegia

"Tram-track" cranial calcifications

Tuberous Sclerosis

Autosomal dominant tumor syndrome characterized by:

Cutaneous angiofibromas

visceral cysts

renal angiomyolipomas

Harmartomas of other tissue including CNS

Cardiorhabdomyomas

Complications: seizures

Rare autosomal dominant conditions characterized by:

retinal and/or cerebellar hemangioblastomas

increased risk of bilateral renal cell carcinoma

neoplasms or cysts in the liver, pancrease, or kidney

Osler-Weber-Rendu

(hereditary hemorrhagic telangiectasia)

Autosomal dominant characterized by:

Congenital telangiectasias (epitaxis, GI bleeds, hematuria)

No cysts!

Bupropion

Isoniazid

Imipenem

Thiamine deficiency (chronic alcoholism)

Characterized by:

Wernicke's ecephalopathy triad: confusion, ophthalmoplegia, and ataxia

Korsakoff psychosis: lesion of the mammillary bodies or periventricular hemorrhage; leads to irreversible memory loss, confabulation, personality change

"TAN HATS"

Thirst and water balance

Adenohypophysis regulation

Neurohypophysis hormonal release

Hunger

Autonomic regulation

Thermal regulation

Sexual urges

Antidiuretic hormone (ADH)

"Water comes from above the eyes"

Controls hunger; inhibited by Leptin

Destruction leads to anorexia

Controls satiety; stimulated by Leptin

Destruction leads to hyperphagia; craniopharyngioma a common cause

Parasympathetic innervation

Cooling of body temperature

Sympathetic control

Increasing body temperature (heating)

α-synuclein intracellular inclusion

Associated with: Parkinson's Disease and Lewy Body Dementia

Sudden, wild flailing of 1 arm +/- leg

Etiology: contralateral subthalamic nucleus lesion due to lacunar stroke in chronic HTN

Autosomal dominant trinucleotide repeat (CAG) demonstrating anticipation

Neuronal death in caudate nucleus (loss of ACh and GABA) due to NMDA-R binding and glutamate toxicity

Findings: chorea, aggression, depression, dementia; atrophy of striatal nuclues on imaging

(can be mistaken for sustance abuse)

Sudden, jerky, purposeless movements

 Inability to hold their tongue out

Etiology: basal ganglia lesion

Slow, writhing movements, especially of the fingers

Etiology: basal ganglia lesion

(usually presents alongside chorea)

Kluver-Bucy Syndrome: hyperorality, hypersexuality, disinhibited behavior

Etiology: associated with HSV-1

Disinhibition and deficits in concentration, orientation, and judgment

Reermergence of primitive reflexes possible

Inspilateral intention tremor, limb ataxia; fall toward side of the lesion

Cerebellar hemispheres are located laterally, lateral limbs affected

Acute paralysis, dysarthria, dysphagia, diplopia, and loss of consciousness

Etiology: very rapid correction of hyponatremia; results in demyelination of the pons

Nonfluent aphasia with impaired comprehension

Etiology: both Broca and Wernicke lesions

Fluent speech and intact comprehension but poor repetition

Etiology: lesion of the arcuate fasciculus (connects Broca's and Wernicke's)

Motor deficits: contralateral upper limbs and face

Sensory deficits: contralateral upper limbs and face

Special deficits: Broca's and Wernicke's (Global aphasia); hemineglect if on non-dominant (usually right) side

Motor deficits: Contralateral Lower limb

Sensory deficits: Contralateral lower limb

Usually 2^o to unmanaged HTN

Contralateral hemiparesis (internal capsule), hemiplegia (striatum)

Contralateral hemiparesis (lateral corticospinal tract)

Decreased contralateral proprioception (Medial lemniscus)

Ispilateral hypoglossal dysfunction (caudal medulla - hypoglossal nerve; tongue deviates toward lesion)

Lateral medullary (Wallenberg's) Syndrome

Vomiting, vertigo, nystagmus (vestibular nuclei)

Loss of pain, temperature, senstion on Limb/face (lateral spinothalamic/spinal trigeminal nucleus)

Dysphagia, hoarseness, decreased gag reflex

Ispilateral Horner's syndrome (sympathetic fibers)

Ataxia, dysmetria (Inferior cerebellar peduncle)

Nucleus ambiguus

Lateral Pontine Syndrome

Vomiting, vertigo, nystagmus (vestibular nuclei)

Paralysis of face, decreased lacrimation/salivation, decreased taste of anterior 2/3 of tongue, decrease corneal reflex (Facial nucleus)

Decreased facial pain and temperature sensation (spinal trigeminal nerve)

Decreased ipsilateral hearing (cochlear nuclei)

Ipsilateral Horner's syndrome (sympathetic fibers)

Middle and Inferior Cerebellar peduncle

Contralateral hemianopsia with macular sparing

(occipital cortex, visual cortex)

Impingement of CNII, visual field defects

(berry aneurysm)

Associated with chronic HTN; affects small vessels (lateral striate - basal ganglia/thalamus)

Histological findings: Lipohyalinosis and microatheromas of vessels

Occur at bifurcations in the Circle of Willis

Most common: AComm

Associated with ADPKD, Ehlers-Danlos syndrome, Marfan's syndrome

Epidural hematoma

Rupture of the meningeal artery (branch of maxillary artery)

2^o to trauma

Rapid expansion can cause transtentorial (falx or tentorium) herniation and CNIII palsy

Subdural hematoma

Rupture of bridging veins

Develops over time due to slow bleeding veins

Seen in elderly, alcoholics, blunt trauma, shaken baby

Cresent-shaped hemorrhage that crosses suture lines

Midline shift but gyri perserved

Cannot cause herniation

Subarachniod hemorrhage

Due to berry aneurysm

Rapid time course: "worst headache of my life"

Bloody or yellow (xanthochromic) spinal tap

2-3 days afterwards, risk of vasospasm due to blood breakdown (Rx with nimodipine) and rebleed

Composed of Fasciculus Cuneatus and Gracilis

Afferent: pressure, vibration, proprioception, touch

1st order neuron: Afferent travels to DRG and into spinal cord; ascends ipsilateral in dorsal columns

2nd neuron: Synapse in the cuneatus or gracilis neuron (medulla) and decussates  to synapse in VPL of thalamus

3rd Neuron:  Synapse in the sensory cortex

Afferent: Ascending pain and temperature sensation

1st Neuron: sensory nerve ending to DRG and spinal cord; synapse on ipsilateral gray matter (spinal cord)

2nd neuron: decussates via anterior white commisure of spinal cord and ascends contralaterally

3rd neuron: synapse on VPL of thalamus and travels to the sensory cortex

Carries efferent motor stimuli

1st neuron: UMN in 1^o  motor cortex descends ipsilaterally via internal capsule; decussates at caudal medulla and descends contralateral

2nd order Neuron: Synapse at anterior horn cell body and LMN exits the spinal cord

3rd neuron: LMN innervates Neuromuscular junction

Weakness

Increased reflexes

Increased tone

Positive Babinski test

Spastic paralysis

Clasp knife spasticity

No atrophy, fasciculations

Weakness

Atropy

Fasciculations

Decreased reflexs and tone

Negative Babinski, spastic paralysis, clasp knife spasticity

Infection with the polio virus (picornavirus)

Enters via the GI system and replicates in the small intestines and oropharynx; hematogenous spread to CNS

Destroys anterior horns of spinal cord

Findings: LMN findings, lymphocytosis in CSF, flu-like symptoms

Demyelination of CNS white matter (oligodendrocytes) of the cervical region

Random and assymmetric lesions

Triad: Scanning speech, intention tremor, nystagmus (intranuclear ophthalmoplegia) "SIN"

Werdnig-Hoffman Disease

(Infantile spinal muscular dystrophy)

Autosomal recessive disease which involves destruction of the anterior horns

Presents early in life as "floppy baby"

Tongue fasciculations, and LMN lesion signs

Median age of death: 7 months

Amyotrophic Lateral sclerosis (ALS)

Loss of anterior horn and lateral corticospinal tract; signs of UMN and LMN lesion

No sensory, cognitive, or oculomotor deficits

Associated with defect in superoxide dismutatse I (SOD1)

Presents as fasciculations and eventual atrophy; progressive and fatal

Riluzole modestly lengths survival by decreasing presynaptic glutamate release

Autosomal-recessive trinucleotide repeat (GAA) in gene that codes for frataxin

Impairment of mitochondrial function

Presents as a child with kyphoscoliosis

Findings: staggering gait, frequent falling, nystagmus, dysarthria, pes cavus, hammer toes

Dies of Hypertrophic Cardiomyopathy

Characterized by Ptosis, Anhydrosis, Miosis 

Etiology: lesion of the 3-neuron oculosympathetic pathway (hypothalamus, intermediolateral column, superior cervical sympathetic ganglion)

Common causes: Pancoast tumor, Brown-Sequard syndrome above T1, late-stage syringomyelia

Dermatologic landmarks

T4

T7

T10

L1

L4

S2-4

T4: nipple line

T7: xiphoid process

T10: umbilicus

L1: inguinal ligament

L4: knee

S2-4: Sensation to genital/anal region/erection

Location: dorsal aspect of the brainstem, superior to the cerebellum (and superior colliculi)

Function: Melatonin secretion for circadian rhythm

Location: Dorsal aspect of the brainstem, inferior to the pineal gland (anterior to the cerebellum)

Function: conjugates veritcal gaze

can be damaged with a pinealoma

Location: Dorsal aspect of the brainstem inferior to the superior colliculi and pineal gland, just superior to the superior cerebellar peduncles

Function: spacial auditory integration

Functions:

Eye movement (SR, IR, MR, IO)

Pupillary constriction (Parasympathetic fibers from Edinger-Westphal nucleus)

Accomodation

Eyelid opening (levator palpebrae)

Functions:

Muscles of mastication

Facial sensation (ophthalmic, maxillary, mandibular branches)

Functions:

Facial muscles

Taste from anterior 2/3 of tongue

Lacrimation

Salivation (sublingual, submandibular glands)

Eyelid closing (orbicularis oculi)

Stapedius muscle in ear (noise reduction)

Functions:

Taste from posterior 1/3 of tongue

Swallowing

Salivation (parotid gland)

Carotid body and sinus afferent

Stylopharyngeus (elevates pharynx and larynx)

Masseter, Temporalis, Medial pterygoid (close mouth)

Lateral pterygoid (open mouth)

All intervated by CN V₃

Lens is tonically stretched (concave) due to zonular fibers

Contraction of ciliary muscles (muscarinic) causes relaxation of the zonular fibers

Lens relaxes (more convex)

Ciliary muscles relax (removal of PS stimulation)

Zonular fibers contract and stretch lens (concave)

Pupillary constriction

Muscle: pupilary sphincter (circular) muscle

Innervation: Parasympathetic control (CNIII carries PS fibers from Edinger-Westphal nucleus to ciliary ganglion)

Dilation of pupil

Muscle: Pupillary dilator (radial) muscle

Innervation: Sympathetic control (α) (T1 preganglionic sympathetic fibers to superior cervical ganglion; long ciliary nerve (postganglionic) runs with V₁)

Afferent pupillary defect (CNII lesion or retinal detachment)

Results in decrease bilateral constriction when light is shown in affected eye

Right temporal lesion (MCA)

Upper: Meyer's loop lesion (temporal)

Lower: Dorsal optic radiation lesion (parietal)

AKA MLF Syndrome

Lesion in the medial longitudinal fasciculus causes a medial rectus palsy on lateral gaze

MLF connects CN VI to contralateral CNIII for medial rectus

 Associated with Multiple Sclerosis

Senile plaques: extracellular Aβ-amyloid core

Neurofibrillary tangles: intracellular abnormally phosphorylated tau protein = insoluble cytoskeletal elements

(tangles directly correlates w/degree of dementia)

Glioblastoma Multiforme (GBM) (Grade IV astrocytoma)

Histology

Pseudopalisading pleomorphic tumor cells (border central areas of necrosis and hemorrhages)

GFAP - stain of astrocytes

Most common in cerebral hemisphere that can cross  the corpus callosum ("butterfly glioma")

Meningioma

Histology

Spindle cells concentrically arranged in a whorled pattern with psammoma bodies

Most often in the convexities of hemispheres and parasagittal region; arise from arachnoid cells

Schwannoma

Histology

Schwann cell origin, often located around CNVIII (Acoustic schwannoma) cerebellopontine angles

S-100 positive

Bilateral schwannoma in NF-2