2025 MSB_Neurology Special Senses

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NEUROLOGY SPECIAL SENSES NEUROLOGY SPECIAL SENSES Embryology 86 Physiology of the Ear 113 Cranial Cavity Structures 87 Ophthalmology 114 Neurons & Glial Cells 88 Aq. Humor Production & Drainage 115 Brain Vasculature 89 Glaucoma 116 BBB & Meningitis 90 Retinopathies 117 Stroke 91 Lysosomal Storage Diseases 118 Vascular Pathologies 92 Ocular Physiology 119 Herniation Syndromes 93 Pupillary Defects 120 Subcorticol Structures 94 Visual Field Defects 121 Neurodegenerative Disorders 95 Parkinson's Pharm + Dopamine Pathways 96 Dementia & Multiple Sclerosis 97 Notes 122 Limbic System 98 References 123 124 Tumors of the Brain 99 Brainstem Anatomy 100 Brainstem Function & Cranial Nerves 101 Circle of Willis & Rule of 4's 102 Spinal Cord & Tracts 103 Spinal Cord Lesions 104 Seizures & Antiepileptics 105 CNS Pathologies 106 Peripheral Neuropathies 107 Motor Neuron Lesions 108 Anesthetics 109 Neuromuscular Junction 110 Clinical Neurology 111 Neurocutaneous Disorders 112 LEGEND PHARMACOLOGY RISK FACTORS MEMORY TRICKS PATHOLOGY 8Embryology NEURAL PLATE DAY NEUROectOdeRM Derivatives Neural Crest 18 Cell Derivatives Neurons All neurons in the CNS Neuroglia Astrocytes, Oligodendrocytes, NOTOCHORD eninges (pia & arachnoid) Ependymocytes, Choroid plexus cells ectoderm to dontoblasts differentiate into Neurohypophysis (posterior pituitary gland) to form neural plate racheal cartilage (pineal gland) nterochromaffin-like cells Optic nerve aryngeal cartilage Retina Muscles of the iris CRESTS Plate gives rise neural arafollicular C cells tube neural crest cells Microglia are the only neuroglial cells drenal medulla & All ganglia NEURAL TUBE with a Mesodermal origin. They act as chwann cells the "Macrophage-like" cells of the CNS. eptum (aorticopulmonary) REMEMBER the M's! 21 MOTEL Neural Tube Regionalization PASS Adult derivatives of: Walls Cavities NEURAL TUBE DEFECTS Telencephalon Cerebral Lateral ANENCEPHALY: Failure of rostral neuropore to close Hemispheres Ventricles "An" without Forebrain Diencephalon Thalamus, "Enkephalos" without forebrain Third (prosencephalon) Hypothalamus Ventricle Clinical findings: POLYHYDRAMNIOS: Midbrain Cerebral Mesencephalon Midbrain Excessive amniotic fluid for gestational age (mesencephalon) Aqueduct Impaired CNS swallowing Hindbrain Metencephalon Pons upper part SPINA BIFIDA VARIANTS Cerebellum OCCULTA MENINGOCELE MYELOMENINGOCELE Myelencephalon Medulla lower part Spinal Cord Memory Tricks "Fore" in front Forebrain Telepathy in your cerebral hemispheres" Telencephalon Diet (food centers in hypothalamus)' = Diencephalon M for Midbrain Mesencephalon No herniation, Meninges Meninges "Mes, Met, My follows alphabetical order!" associated with tuft herniate AND of hair or bony defect ONLY neural tube herniate LISSENCEPHALY HOLOPROSENCEPHALY failure of caudal neural tube to close "SMOOTH BRAIN" Holo = "failure to divide" of MARKERS CAUSES Failure of neuronal the prosencephalon into AFP migration leading the cerebral hemispheres. Folate deficiency AChE Diabetic mother to the absence of Associated with Patau Obesity 86 syndrome (trisomy 13) & *Spina Bifida occulta has sulci and gyri. normal AFP Fetal Alcohol Syndrome. Cranial Cavity Structures POSTERIOR FOSSA MALFORMATIONS SYRINGOMYELIA CHIARI MALFORMATIONS DANDY-WALKER Cystic enlargement of the spinal Small posterior fossa MALFORMATION cord (central canal) Agenesis of the cerebellar Tonsilar herniation vermis Compresses fibers crossing in the anterior white commissure Spina bifida SYRINGOMYELIA (myelomeningocele) Cystic enlargement of the 4th ventricle Spinothalamic tract affected: Bilateral pain and temperature CHIARI TYPE I CHIARI TYPE II loss malformation: malformation: Enlarged posterior fossa Classic "cape-like" distribution Herniation of II Can lead to: Displacement of NON-COMMUNICATING structure (cerebellar structures (cerebellum HYDROCEPHALUS tonsils) & medulla) VENTRICULAR SYSTEM LATERAL VENTRICLES (2) CSF drains into the venous system via arachnoid INTERVENTRICULAR granulations in the FORAMINA (2) superior sagittal sinus. VENTRICLE CEREBRAL AQUEDUCT Foramen of Luschka: Lateral 4TH VENTRICLE Foramen of Magendie: Medial CSF is produced by to spinal cord Ependymal cells in CENTRAL CANAL To subarachnoid space (between arachnoid & pia mater) the Choroid plexus. NORMAL PRESSURE HYDROCEPHALUS Affects older adults (>60 years), idiopathic. COMMUNICATING HYDROCEPHALUS Normal ICP or episodically elevated. Decreased CSF absorption CSF Decreased CSF absorption by arachnoid granulations. accumulation dilation of ventricles. Caused by inflammatory disease (e.g., meningitis) or hemorrhage. Wet Wacky Wobbly NON-COMMUNICATING HYDROCEPHALUS Structural blockage of CSF within the ventricular Urinary Cognitive Magnetic system. incontinence Dysfunction Gait Causes include: EX-VACUO HYDROCEPHALUS Cerebral aqueduct stenosis (most common) Extra-ventricular obstruction Enlarged ventricles in response to cortical atrophy. Congenital causes Not true hydrocephalus. Congenital toxoplasmosis infection. Seen in Alzheimer's, Schizophrenia, & advanced Results in: Increased ICP, Papilledema, Herniation stages of other Neurodegenerative conditions. 87Neurons & Glial Cells NEUROGLIA (CNS) NEURONS ASTROCYTE "Astro" "star-like" DENDRITES: Receive signals Most common glial cell CELL BODY ("SOMA"): Maintains the environment Contains organelles & Nissl physical support & repair bodies for biosynthesis component of BBB (blood- brain barrier) AXONS: Transmit signals Marker GFAP+ Away from the cell body Reactive Gliosis: Astrocytes hypertrophy to serve MYELIN SHEATH: Insulating a protective role during CNS injury. layer allowing electrical signals to quickly propagate down axons MICROGLIA CNS = Oligodendrocytes Macrophages of the CNS PNS = Schwann cells Activated by tissue damage Release inflammatory mediators Recall: Derived from Mesoderm EPENDYMAL CELLS OLIGODENDROCYTES CSF dEPENDs on "EPENDymal" cells! "ol-EGG-odendrocyte" classic "fried-egg" appearance Simple columnar or cuboidal lining Myelinates axons of the CNS ventricles Affected in leukodystrophies Produce/Regulate CSF (degeneration of white matter) PERIPHERAL NERVES AXONAL INJURY Part of nervous system outside the brain and spinal cord Injury EPINEURIUM Distal end Dense connective tissue that surrounds the entire nerve Contains blood vessels Proximal end Wallerian Degeneration Proximal to the Erosion of axon and myelin SCHWANN CELLS injury, axon retracts sheath Distal to the site of Each "Schwone" cell myelinates only PNS axon & cell body grows axonal injury. Occurs in both outward to facilitate CNS & PNS, but regeneration ENDONEURIUM reinnervation. only occurs in PNS. Thin connective tissue that supports individual nerve fibers May be affected in Guillain-Barré syndrome Increased Protein synthesis PERINEURIUM: Increased cell body chromatolysis: Surrounds fascicle spread Nissl substance into 88 Creates the blood-nerve barrier cytoplasm THINK! "Perineurium is imPERImeable to blood" Brain Vasculature CIRCLE OF WILLIS Anterior Cerebral Artery Anterior Communicating Artery Foot Middle Cereabral Toes Artery Genitals ACA Internal Carotid Artery Posterior Communicating MCA Artery Eye Nose Face Posterior Cerebral Artery Lips Teeth Gums Jaw Basilar Artery Tongue Pharynx Vertebral Artery PCA The ICA and the Vertebral artery come together at the base of the brain to become the CIRCLE OF WILLIS (see pg 20) POSTERIOR CEREBRAL ARTERY (PCA) Contralateral homonymous hemianopia (+ macular sparing due to MCA blood supply) Alexia without Agraphia is able to spell and write but unable to read MIDDLE CEREBRAL ARTERY (MCA) Contralateral weakness of lower face & upper limb +/- Aphasia Associated with strokes +/- Hemineglect M Associated with strokes of LEFT MCA of dominant hemisphere RIGHT MCA nondominant hemisphere BROCA'S APHASIA Inferior frontal gyrus GERSTMANN SYNDROME BROCA'S BROKen Articulation Stroke of angular gyrus Can understand but not produce speech GLOBAL Agraphia WERNICKE'S APHASIA APHASIA WERNICKE'S Word Salad Infarction of Unable to understand speech BROCA'S Acalculia TETRAD Finger Superior temporal gyrus Agnosia + WERNICKE'S CONDUCTIVE APHASIA + ARCUATE FASICULUS Left-Right Affects arcuate fasciculus = connection Disassociation between Broca's & Wernicke Only repetition impaired ANTERIOR CEREBRAL ARTERY (ACA) Contralateral lower limb weakness > arm weakness Urinary Incontinence Contralateral lower limb sensory deficits 89Blood Brain Barrier & Meningitis 1 Tight Junctions The BBB is made up of BBB DAMAGE Astrocyte four components: Foot Process Causes: Capillary Brain Infection & 1. TIGHT JUNCTIONS Lumen Tumors: Break tight 2. BASEMENT MEMBRANE junctions Vasogenic 3. PERICYTES Edema. 4. ASTROCYTE FOOT PROCESSES Hyperosmolar Solutions Nonpolar/Lipid-Soluble (e.g., mannitol): Substances cross rapidly. Vasodilation leading to 2 Glucose & Amino Acids Increased Permeability 3 cross slowly. of BBB Endothelial Cells Pericyte MENINGES: "PAD" the Brain (from inside to outside) EPIDURAL SPACE: Located between dura PIA MATER: Thin fibrous layer, derived and skull. from neural crest. Contains fat and vessels. RACHNOID MATER: Middle layer, web- SUBARACHNOID SPACE: like connections, derived from neural crest. Located between arachnoid and pia mater DURA MATER: Site of CSF flow Thick outer layer, derived from mesoderm MENINGITIS Signs & Symptoms Diagnostic Criteria NECK STIFFNESS Opening Cell Type Protein Glucose Pressure FEVER HEADACHE Bacterial PMNs D ALTERED MENTAL STATUS Fungal/TB LYMPHOCYTES D PHOTOPHOBIA D N&V Viral NORMAL LYMPHOCYTES NORMAL NORMAL KERNIG'S SIGN: Pain on extension BRUDZINSKIS SIGN: Passive flexion Diagnosed of the knee when the hip is of the neck provokes lifting of via lumbar flexed in supine position. the legs in supine position. puncture TIMELINE: Most Common Pathogens During Developmental Stages NEWBORN (0-6 MONTHS) CHILDREN (6 MOs 6 YRs) ADULT (6 60 YRs) ADULT (> 60 YRs) Group Strep S. pneumoniae S. pneumoniae S. pneumoniae E. coli N. meningitidis N. meningitidis Listeria Listeria H. influenzae type Enterovirus H. Influenzae Type B TREATMENT: Ampicillin + TREATMENT: Vancomycin + TREATMENT: Vancomycin + TREATMENT: Vancomycin + Aminoglycoside Ceftriaxone Ceftriaxone Ceftriaxone + Ampicillin 90 Stroke TRANSIENT ISCHEMIC ATTACK (TIA) ISCHEMIC STROKE TIMELINE Brief, reversible episode of neurologic dysfunction WITHOUT RED NEURONS acute infarction. Typically resolves 12-24 HRS Presentation: May present with amaurosis fugax (transient vision loss) due to retinal artery emboli! 15 min STROKE Morphology: Eosinophilic cytoplasm, pyknotic nuclei, loss of substance ISCHEMIC Thrombotic NEUTROPHILIC INFILTRATION Embolic STROKE 20% Hypoxic HEMORRHAGIC FOCAL ISCHEMIA: 80% STROKE Generally due to atherosclerosis, which can lead to thrombosis or Central necrosis occurs with infiltration. emboli. GLOBAL ISCHEMIA: Due to hypotension leading to damage in watershed zones (areas of WATERSHED AREAS 3-7 DAYS poor perfusion). ACA-MCA Most Vulnerable Regions of Watershed Ischemia: Hippocampus Phagocytosis begins with macrophages clearing debris. Neocortex REACTIVE GLIOSIS Purkinje cells 1-2 WEEKS areas MCA-PCA Watershed Hippos Need Pure Vascular proliferation around the necrotic Immediate Actions: area as gliosis progresses. ! tPA (Tissue Plasminogen Activator) administration within 4 hours of onset if there is no hemorrhagic risk. GLIAL SCAR ! Order Non-Contrast CT to rule out hemorrhage! Thrombectomies: Can be performed on large arteries. Anticoagulants can reduce further thrombotic risk. LACUNAR INFARCTS Formation of permanent fibrous tissue scar with astrocyte hypertrophy. Clinical Presentation: Typically does not present with cortical signs (e.g., aphasia, neglect, or visual loss). RISK FACTORS Presents as specific syndromes based on Hypertension (HTN) and lesion location (e.g., pure motor hemiparesis). Diabetes Lipohyalinosis of lenticulostriate arteries Located in: Deep subcortical brain regions 91Vascular Pathologies ANEURYSM: Dilation of the arterial wall due to vessel wall weakening BERRY ANEURYSM "clinically silent" ANTERIOR COMMUNICATING ARTERY (ACOM) Compression of optic chiasm bitemporal hemianopia Ischemia in the Anterior Cerebral Artery (ACA) distribution MIDDLE CEREBRAL ARTERY (MCA) Ischemia in MCA distribution POSTERIOR COMMUNICATING ARTERY (PCOM) Compression of Cranial Nerve III (CN III) RISK FACTORS Ipsilateral CN III palsy Mydriasis (dilated Autosomal Dominant pupil) + "down and out" eye position due Polycystic Kidney Disease to unopposed lateral rectus and superior (ADPKD) Hypertension (HTN) oblique muscle action. Smoking Age The junction of the ACOM & ACA is the most common site of berry aneurysm formation. Aneurysm may progress to: INTRACRANIAL HEMORRHAGE INTRAPARENCHYMAL HEMORRHAGE: SUBARACHNOID HEMORRHAGE: Collection of blood within the brain parenchyma. Sudden bleeding into the subarachnoid space. Most commonly due to ruptured CHronic Hypertension BERRY ANEURYSM. Hyalinization of arterioles CLINICAL FEATURES: Sudden severe headache CHarcot-Bouchard ("thunderclap headache"). microaneurysms of the lenticulostriate arteries Followed by loss of consciousness (LoC). Most common in Basal ganglia May present as meningismus (stiff neck)! HEMATOMAS SUBDURAL EPIDURAL Blood collection between dura and arachnoid mater. Blood collection between skull and dura mater. Key Features: Secondary to trauma (acute) Concave/Crescent-shaped Rupture of the Middle Crosses suture lines Meningeal Artery (MMA) hronic alcoholics at higher risk Key Features: Bridging veins rupture Biconvex and does not cross Chronic: Elderly patients suture lines. Acute: Trauma May present with a lucid interval. 92 THINK about the 3 fighters will break your MMA Foramen SPINosum. Herniation Syndromes Falx cerebri HIGH INTRACRANIAL PRESSURES 2 SUPRATENTORIAL (1-3) 1. UNCAL Compression of the: PCA, CN3, aqueduct of Sylvius & midbrain Initially presents with ipsilateral CN 3 palsy (fixed and dilated pupil) Can compress contralateral cerebral puduncle Ipsilateral hemiapresis Kernohan's Phenomen Tentorium Uncus Cerebelli 2. CENTRAL/TRANSTENTORIAL Caudal displacement of brainstem rupture of CUSHING Triad: signs of raised ICP basilar artery Duret hemorranges (small ruptures in 1. Respiratory Depression midbrain/pons) REFLEX 2. Hypertension Coma deCORticate decerebrate loss of relfexes 3. Reflexive Bradycardia 3. CINGULATE/SUBFALCINE & OCO, SENSED BY Herniation under falx cerebri -> compresses ACA CHEMORECEPTORS Coma + contralateral lowerlimb weakness/sensory loss VASOCONSTRICTION BLOOD PRESSURE INFRATENTORIAL (4-5) CAROTID BARORECEPTOR STRETCH 4. UPWARD CEREBELLAR Cerebellar & medullary dysfunction CN IX FIRING TO SOLITARY NUCLEUS 5. TONSILLAR HEART Into foramen magnum compress brainstem vital CN FIRING TO NODAL TISSUE RATE respiratory/CVS centres affected coma & death Chiari Malformation ABNORMAL POSTURING Causes: Cerebrovascular haemorrhages, Tumors, Electrolyte abnormalities, Herniation, Encephalitis, Reye's Syndrome deCORticate = arms flexed toward CORE loss of CORtical inhibiton of rubrospinal tract (still intact) DecERebrate = has more & Decorticate Position Extended upper limbs Rubrospinal tract transected 93 Decerebrate PositionSubcortical Structures THALAMUS BASAL GANGLIA Relays all sensory info *except olfaction Umbrella of structures consisting of: CAUDATE NUCLEUS MEDIAL ANTERIOR STRIATUM (PUTAMEN GLOBUS PALLIDUS) LP LD SUBTHALAMIC NUCLEUS VA PULVINAR SUBSTANTIA NIAGRA VL VP VPL VPM Functions: MEDIAL GENICULATE Planning and coordinating BODY (MGN) LATERAL GENICULATE BODY (LGN) movement Decision making HYPOTHALAMUS MGN MusIC from IC (inferior colliclus) relay centre for HEARING LGN Look from optic tract GLUT Excitatory Cerebral Cortex relay centre for VISION GABA Inhibitory GLUT Thalamus VPL Very Painful Limbs relay sensory info to the body When we don't want to move: spinothalamic & dorsal columns GABA Inhibitory signals are sent to the Thalamus to avoid stimulation of VPM Very Painful Mouth Globus pallidus internal Substantia nigra pars reticula the Cerebral Cortex. relay sensory info to the face VL/VA = cerebeLum & bAsal ganglia rect Pathway (D1) = Excitatory Indirect Pathway (D2) Inhibitory GLUT GLUT GLUT Cerebral Cortex Cerebral Cortex Substantia nigra GLUT Globus Pallidus Striatum Thalamus pars compacta Substantia nigra Striatum pars compacta GABA GABA Caudate Globus Pallidus external GABA Nucleus Globus pallidus internal Substantia nigra pars reticula Globus pallidus internal Subthalamic Substantia nigra pars GABA nucleus reticula HYPOTHALAMUS: maintain homeostasis by regualting the Adenohypophysis (Ant Pit) & Neurohypophysis (Post. Pit) LATeral nucleus = "stim the LAT, get FAT" Paraventricular nucleus Preoptic nucleus ENtromedial = "stim the VEN, get Thin" Dorsomedial nucleus Posterior hypothalamic nucleus Anterior = "A/C" = Cooling, pArasympthatic Paraventricular nucleus Ventromedial nucleus Supraoptic nucleus Mammilary bodies PoSterior = Shivering, Sympathetic Suprachiasmatic = "You need sleep to be Suprachiasmatic nucleus charismatic!" circadian rhythm Arcuate nucleus Infundibular stalk Supraoptic = ADH (water balance) Pituitary gland Paraventricular = "Para Parturition" Oxytocin 94 Preoptic GnRH Neurodegenerative Disorders Cortex HUNTINGTON'S DISEASE Autosomal Dominant Caudate & Anticipation leading to earlier onset of disease due to Putamen increased CAG trinucleotide repeats in the HUNTington (GTT) gene on chromosome 4 (4 letters) Accumulation of repeats protein deposition in striatum atrophy of caudate and putamen Degeneration of the Striatum leads to CHOREA ACh Tetrabenezine blocks VMAT in the GABA presynaptic neuron thereby reducing the Substantia nigra amount of dopamine in the synaptic cleft Dopamine ALZHEIMER'S DISEASE PARKINSON'S DISEASE Leading cause of dementia Loss of dopaminergic neurons of the substania Neuronal cortex degeneration widespread nigra pars compacta. cortical atrophy (narrowed gyri/widened sulci) Results in a decrease in acet ACh Clinical Features: from the nucleus of meYnert "TRAPS" Genetics: ApoE-2: DEC risk of sporadic form remor: resting, pill rolling ApoE-4: INC risk of sporadic form cogwheel, lead pipe APP, PSEN1, PSEN2 = familial forms (early onset) Increased risk in Down syndrome because APP kinesia includes: is located on chromosome 21 Expressionless face Neurofibrillary Tangles Senile Plaques Shuffling Decreased repetitive movements ostural instability huffling gait, mall handwriting ACh Serotonin Dopamine Deposition of B-Amyloid & accumulation of Neurofibrilary PARKINSON-LIKE SYNDROME tangles cortical degradation especially in the Hippocampus can be due to: of Alzheimer's ntipsychotics TREATMENT Anomia: cant remember names eserpine Memantine Apraxia: loss of ability to carry etoclopramide out movements Acetylcholinesterase Inhibitors (increase ACh) Agnosia: can't recognize familiar THINK! Cogwheel rigidity in the NMDA Antagonists objects, tastes, etc. ARM Rivastigmine Aphasia: inability to express through speech Lewy bodies (alpha-synuclein) Galantamine intracellular eosinophilic Amnesia: memory loss 95 inclusionsParkinson's Pharmacology & Dopamine Pathways CENTRAL DOPAC Drug Class/ Mechanism of Name Action Memory Trick Dopamine 3MT COMT L-DOPA CarbiDOPA L-Dopa + blocks carbiDOPA dopa-decarboxylase SELEGILINE ENTACAPONE RASAGILINE MAO-B Inhibitor you want LINEs when MAO-B Brain > RasagiLINE peripheral you "MAO" the lawn L-DOPA Dopamine Dopa- decarboxylase Al CAPONE COMiTs EntaCAPONE COMT-Inhibitor crimes CARBIDOPA DINE at a DRIve through AmantaDINE Blocks dopamine- PERIPHERAL reuptake channel DRI dopamine reuptake inhibitor *Bromocriptine (ergot) AMANTADINE Pramipexole *Less preferred due to Dopamine Agonist toxicity Ropinirole NOTE! DA-Reuptake BROMOCRIPTINE Channel Antipsychotics primarily target the mesolimbic pathway. PRAMIPEXOLE ROPINIROLE Decreased dopamine from the Decreased VTA to the nucleus accumbens positive symptoms DA-Receptors DOPAMINE PATHWAYS MESOLIMIBIC Da from VTA projects to NUCLEUS ACCUMBENS (NA) VENTRAL TEGEMENTAL AREA (VTA) Psychosis & positive symptoms (i.e. hallucinations, delusions) "Vere the Trouble Arises!" Tx: Antipsychotics MESOCOTRICOL Da from VTA projects to PREFRONTAL CORTEX Decreased Da in schizophrenia negative symptoms (i.e. flat affect, poverty of thought, etc.) Nucleus Accumbens NIGROSTRIATAL Hypothalamus Da from Substantia Nigra to STRIATUM VTA Anterior Antipsychotics decrease Da in this pathway Pituitary extrapyramidal symptoms (i.e. Parkinsonism) Substantia Nigra TUBEROINFUNDIBULAR Da = Dopamine Da from hypothalamus to ANTERIOR PITUITARY Da & prolactin are INVERSELY related Antipsychotics (block Da) 96 Increased prolactin Galactorrhea & Amenorrhea Dementia & Multiple Sclerosis DEMENTIA THINK! D.I.R.E. DELIRIUM Insidious Decreased attention Progressive ecline in Cognitive Function Rapid onset Irreversible mpairment Reversible Short-term memory unaffected ule out Delirium Short-term memory affected (Immediate recall only!) Altered mental status Normal mental status xclude mental disorder TYPES OF DEMENTIA FINDINGS LEWY BODY: Visual ha-LEWY-cinations Intracellular Lewy Bodies Lewy Body dementia = cognitive & motor symptoms onset 2° to Parkinson's VASCULAR: Look for Hx of HTN & Diabetes Multiple cortical infarcts + Repeated strokes/ischemia subcortical infarcts "Step-wise" decline in cognitive ability FRONTOTEMPORAL (AKA PICK DISEASE) Hyperphosphorylated tau Decline in cognition & impulsive behaviors Pick bodies Atrophy of frontal & temporal lobes CREUTZFELDT-JAKOB Prion sheets (PrPD, PrPDC) Rapidly progressive dementia with myoclonus Spongiform cortex 14-3-3 protein in CSF An acquired form of autoimmune Uhthoff's Phenomenon mylein degeneration in the CNS Impaired conjugate Symptoms of MS are worsened with lateral gaze heat sensitivity like when taking a RISK FACTORS Caused by damage to medial hot bath! longitudinal fasciculus Female Hx of EBV High Latitude Genetics Low Vitamin D Smoking Baseline Relapsing Remitting pattern of disease progression is the CLINICAL FEATURES: most common subtype of MS. Internuclear Ophthalmoplegia Optic Neuritis (early sign present in Nystagmus 20% of all MS patients) Urge incontinence DIAGNOSIS: Non-specific UMN/LMN signs R MRI: periventricular TREATMENT: Affected eye (R) is unable to adduct on c/l gaze plaques (gold 17 DMARDs (i.e., IFN-B) standard) Steroids Unaffected eye (L) abducts with nystagmus CSF: Oligoclonal bands of IgG 97Limbic System Fornix Corpus callosum 5 F's Pineal gland CEREBELLUM 1. FEEDING 2. FLEEING Anterior Lobe 3. FIGHTING 4. FEELING 5. FORNICATING DIENCEPHALON Posterior Lobe Anterior group CEREBRUM nuclei Cingulate gyrus Amygdaloid Parahippocampal body gyrus Lateral regions of Vermis Mamillary body Hippocampus the cerebellum Spine of the Cerebellum affects Structure Function Lesion affect the Limbs! Spinal (Axial) area of our bodies! AMYGDALA Emotion Kluver-Bucy Syndrome: disinhibition Flocculonodular lobe coordinates with CN VIII to (hyperphagia, hypersexuality) assist with balance and posuture HIPPOCAMPUS Memory Antrograde amnesia Neurons from the Cerebellar Puducle crosses twice CIGULATE at the Medulla Neurological deficits are Ipsilateral Emotion & GYRUS Autonomic dysfunction behaviour WERNICKE KORSAKOFF CLINICAL SIGNS MAMILLARY BODIES MeMory SYNDROME associated with Cerebellar injury include: (due to thiamine deficiency) Downbeat Nystagmus Truncal Ataxia Dysdiadochokinesia Romberg sign WERNICKE'S KORSAKOFF Positional drift Past pointing Due to thiamine deficiency Look out for patient with chronic alcoholism OR malnutrition! = Th1am1ne REMEMBER! Cofactor for dehydrogenase enzyme reactions: COAT RACK Ipha-ketoglutarate dehydrogenase Confusion etrograde amnesia ransketolase (HMP shunt) ATP phthalmoplegia nterograde amnesia yruvate dehydrogenase BOOSTER taxia onfabulation ranched-chain ketoacid dehydrogenase hiamine Deficiency* orsakoff Syndrome Deficiency causes Ber1 Ber1 *Give thiamine before dextrose! REVERSIBLE PERMANENT INCREASE in RBC transketolase after Dx thiamine administration DRY WET Polyneuropathy, High-output 98 symmetric wasting cardiac failure Tumors of the Brain ADULT (Older = Typically SUPRAtentorial) GLIOBLASTOMA MULTIFORME PITUITARY ADENOMA Midline/Malignant Crosses midline (corpus Classification: callosum) Non-functional Butterfly appearance Mass effect Histology: Bitemporal hemianopsia Pseudopalisading (border Functional around central area of necrosis) Lactotroph vs. Somatotroph GFAP OLIGODENDROGLIOMA SCHWANNOMA Histology: "SCHW-annoma" Fried-egg appearance Chicken wire capillaries S-100 Often calcified Cerebellopontine angle Hearing loss (CN VIII) Winking (facial nerve, CN VII) MENINGIOMA "Momma, you see the PSA?" HEMANGIOBLASTOMA Psammoma bodies, Spindle cells, Arachnoid origin Blood/EPO Vessels Histology: Benign & superficial Thin-walled capillaries Female Male (PsA MOMMA) Associated with VHL (Von Psammomoma bodies Hippel-Lindau syndrome) laminated calcifications PEDIATRIC (Younger = Typically INFRAtentorial) Homer-Wright rosettes Rosenthal fibers PseudoROSEettes PILOCYTIC ASTROCYTOMA EPENDYMOMA MEDULLOBLASTOMA "Pilocytic... think Posterior!" "Get your MOMMA Roses "Blast the HOMER-run!" for her birthday!" Found in Posterior fossa HOMER-Wright rosettes Most common 1° Pediatric brain tumor Perivascular pseudoROSEttes Second most common malignant Associated with Neurofibromatosis pediatric brain tumor Low-grade Rosenthal fibers Type 2 Commonly involves cerebellum GFAP Both Medulloblastoma & Ependymoma 99 often compress the 4th ventricle!Brainstem Anatomy ANTERIOR VIEW CROSS SECTION POSTERIOR VIEW MIDBRAIN MIDBRAIN Cerebral Peduncle MIDBRAIN Substantia Nigra Red Nucleus CN Medial Geniculate Nucleus Medial Lemniscus Superior Colliculi Medial Longitudinal Fasciculus Mesencephalic Nucleus of Oculomotor Periaqueduct CNV Nucleus Edinger- Aqueduct Westphal Nucleus PONS Superior Cerebral Peduncle Medial Lemniscus Salivary Medial Nucleus Longitudinal Superior Colliculi Fasciculus CN V Nucleus Inferior Colliculi Solitarius Oculomotor Nucleus Medial Geniculate PONS Nucleus PONS Main CN VIII Sensory Abducens Nucleus of Nucleus Superior CNV Middle Dentate CN IX Nucleus CN X Inferior Decussation of Pyramid CN XI the pyramids Spinocerebellar tract Medial Longitudinal Cerebellar Nucleus Medial Lemniscus Peduncles Spinal Nucleus of Choroid CNV MEDULLA Plexus MEDULLA Fasciculus Cuneateus Central Fasciculus Gracilis Canal MEDULLA 100 Brainstem Function & Cranial Nerves MIDBRAIN PONS MEDULLA "Eyes above ears!" RESPIRATORY CENTER: AREA POSTREMA: "Always puking' Pneumotaxic & apneustic centers Known as the vomiting center SUPERIOR COLLICULI Vision INFERIOR COLLICULI Auditory OCULAR (EYE MOVEMENT): NUCLEUS SOLITARIUS: "Sole-lick-tarius" Paramedian pontine reticular PINEAL GLAND: Produces melatonin ensory (CN VII, IX,X) formation PINEALOMA: "Licking the sole of the Neurotransmiter Centers: Causes upward gaze paralysis foot makes me gag!" Associated with Parinaud Syndrome NUCLEUS RAPHE NUCLEUS AMBIGUUS = Speech (hoarseness) RED NUCLEUS: COERULEUS: NUCLEUS: "Ambig-uh-uhs!" otor (CN IX, X) Maintains motor control & muscle tone Norepinephrine Serotonin MIDBRAIN KALLMANN SYNDROME is a caused by defective migration of PONS GnRH-releasing neurons from the olfactory bulbs to the preoptic nuclei. Results in underdeveloped olfactory bulbs (anosmia). MEDULLA CN# CN Name CN Type Word Notable Finding CN OLFACTORY ensory ome Anosmia CN " OPTIC ensory Say Visual Loss CN III OCULOMOTOR otor arry "Down & Out" Pupil CN IV TROCHLEAR otor oney Head tilt AWAY from lesion CN V TRIGEMINAL Reduced sensation V1-3 & anterior 1/3 oth (Sensory & Motor) ut of tongue. Reduced Mastication CN VI ABDUCENS otor My Eye deviated medially Facial weakness CN VII FACIAL oth (Sensory & Motor) rother Taste anterior 2/3 tongue CN VIII VESTIBULOCOCHLEAR ensory ays Sensorineural Deafness CN IX GLOSSOPHARYNGEAL Reduced Gag Reflex oth (Sensory & Motor) Sensory & taste posterior 1/3 tongue CN X VAGUS oth (Sensory & Motor) Hoarsness & Cough rains Uvula deviated away from lesion Torticolis: weakness of traps & CN XI ACCESSORY otor atter sternocleidomastoid, weakness of abduction over 90 degrees CN XII HYPOGLOSSAL Tongue deviated towards lesion otor ost ("Lick your wounds!") 101Circle of Willis & Rule of 4's LATERAL MEDIAL MIDBRAIN PONS CN III MEDULLA CN IV Posterior Cerebral Artery-PCA Posterior Cerebral Artery-PCA MIDBRAIN CN V CN VII CN VI Basilar Artery Anterior Inferior CN VII Cerebellar Artery AICA PONS CN IX Posterior Inferior Cerebellar CN CN XII Anterior Spinal Artery ASA Artery PICA CN XI MEDULLA BRAINSTEM STROKE SYNDROMES Rule of MIDBRAIN Medial Midbrain Syndrome (PCA) CRANIAL NERVES FROM ABOVE THE Oculomotor palsy (eye down & out) AT THE PONS, BELOW THE PONS PONS MEDIAL TRACTS START WITH THE LETTER Locked-In Syndrome: Medial lemniscus (dorsal columns) Medial pons (Basilar Artery) Corticospinal & corticobulbar tracts affected: Quadriplegia, Motor pathways (corticospinal) but Reticular Activating System (RAS) preserved (Conscious) Motor nuclei of cranial nerves Lateral Pontine Syndrome (AICA): Medial/Motor CNs are all factors of 12: Facial nucleus (facial paralysis) Vestibular nucleus (vomiting, vertigo, nystagmus) CN III, IV, VI, XII Spinothalamic tract & sympathetic fibers THINK! Medial longitudinal fasciculus AICA FAICAL SIDE (LATERAL) TRACTS ALL START WITH MEDULLA Sympathetic pathway Spinothalamic tract Medial Medullary Syndrome (ASA) Motor tract (corticospinal) & medial lemniscus affected Spinocerebellar pathway Hypoglossal nerve (tongue movement) Sensory pathway of CN V Lateral Medullary Syndrome (PICA) Nucleus ambiguus (dysphagia, hoarseness) Spinothalamic tract 102 Problems with chewing & speaking Spinal Cord & Tracts SPINAL SPINAL TRACTS = Decussate CORD C4 C6 C7 DORSAL COLUMN SPINOTHALAMIC CORTICOSPINAL T1 C1-C7 exit above Very TRACT TRACT T2 T3 corresponding Patient" T4 Not That Patient" Voluntary vertebrae Movement Fine touch Non-discriminative 16 C8 exits below C7 Vibration touch & above T1 Proprioception Temperature Spinal Tracts Legend Patient waits Pain 1st order neuron All other nerves to decussate at the T10 exit below Not Patient = 2nd order neuron medulla T11 decussates right at 3rd order neuron anterior comissure Spinal cord ends at L1/2 L2 PRIMARY SENSORY CORTEX PRIMARY MOTOR CORTEX L3 Lumbar puncture L4 occur at L3-4 THALAMUS MEDULLA MEDULLA MEDULLA OBLONGATA Upper motor neuron In the spinal cord posterior.horn posterior horn white matter is on the anterior outside, while grey anterior horn Lower motor neuron matter is on the inside. Sensation pathway of the DORSAL COLUMN: comes Cuneatus fasciculus = Upper limb before G!" SPINAL racilis fasciculus = Lower Limb CURVATURES ordosis yphosis coliosis Think! Think! Think! "L" "S" for Kyphosis for Scoliosis for Lumbar Curvature of lumbar vertebrae Curvature of thoracic area area (classic "Swayback") (classic "hunchback") Lateral S curve of spine Associated with: Associated with: Associated with: Duchenne muscular dystrophy Osteoporosis (vertebral compression Syringomyelia Pregnancy fracture) Friedreich ataxia Friedreich ataxia Homocystinuria/Marfans Homocystinuria/Marfans Restrictive lung disease 103 Restrictive lung diseaseSpinal Cord Lesions SPINAL MUSCULAR ATROPHY SUBACUTE COMBINED DEGENERATION (SCD) Congenital degeneration of Caused by Vit B12 deficiency the anterior horns Affects: SYMPTOMS: Spinocerebellar tracts LMN (Lower Motor Corticospinal tracts Neuron) symptoms only Dorsal columns AMYOTROPHIC LATERAL SCLEROSIS (ALS) ANTERIOR SPINAL ARTERY OCCLUSION UMN (Upper Motor Neuron) and LMN defects Spares the dorsal column Sensory tracts spared Damage to the artery of TREATMENT: RiLOUzole Adamkiewicz Gehrig's Disease" SYRINGOMYELIA CAUDA EQUINA SYNDROME Expansion of the syrinx Bilateral disruption of Compression of spinal roots L2 and below second-order spinothalamic L3 neurons SYMPTOMS: L4 Radicular pain Absent knee and ankle TABES DORSALIS reflexes Associated with tertiary Saddle anesthesia syphilis Demyelination of the dorsal column BROWN-SÉQUARD SYNDROME Argyll-Robertson pupil Hemisection of the spinal cord FRIEDREICH ATAXIA SYMPTOMS: Trinucleotide repeats (GAA) Contralateral loss of Impairment in mitochondrial pain and temperature functioning 1-2 spinal levels below Degeneration of the lesion * corticospinal tracts Ipsilateral loss of the dorsal column and corticospinal tracts POLIOMYELITIS Caused by polio virus Destruction of the anterior horn Vertebral column destruction due POTT'S DISEASE to disseminated TB infection! 104 Seizures & Antiepileptics Synchronized, high frequency neuronal firing. Partial (focal) seizures Generalized seizures 2°generalized Impaired consciousness? Tonic-clonic Absence Tonic Myoclonic Atonic (grand mal) (petit mal) Simple Partial Complex Partial children SIGNS SYMPTOMS EPILEPSY Alternating Stiffening Quick & Drop Seizure Blank stare Disorder of recurrent, stiffening & repetitive (falls to floor) no postictal unprovoked seizures movement jerks confusion 3Hz spike wave discharges Causes of Seizures THINK! 'VITAMINS" STATUS EPILEPTICUS Vascular, Infections, Toxins, Autoimmune, Continuous 5min) or recurring seizures Metabolic, Neoplasms, Stress without return to baseline consciousness. MECHANISM DRUG USES ADVERSE EFFECTS MEMORY TRICK OF ACTION VALPROATE Inhibits voltage gated 1st line for tonic-clonic VALPROATE GABA seizures Vomiting, Alopecia, Liver toxicity, Pancreatitis, Rash, Anorexia, Teratogenic, Enzyme inhibition P450 inducer (induce Inhibits voltage gated Partial & status "If they don't SALT the PHENY (zero order tow trucks) gingival hyperplasia (snow), fetal roads, your car will need kinetics) epilepticus prophylaxis a hydan TOIN syndrome TOPIRAMATE Inhibits voltage gated Partial & tonic-clonic Sedation, slow cognition, toPIRATE mate (pirate seizures kidney stones ship on ocean SALT water) 1st line trigeminal CARBAMAZEPINE Refractory period SJS, diplopia, ataxia, neuralgia "chew CARBS with your of voltage gated & partial seizures agranulocytosis cheek (trigeminal)!" LAMOTRIGINE Inhibits voltage gated Partial/generalized SJS "That's Lam(e) rash!" glutamate seizures & pregnancy ETHOSUXIMIDE Inhibits T-type 1st line absence seizures Steven Johnson Syndrome "absence seizures (STS) BENZODIAZEPINES Frequency of Status epilepticus & Sedation, tolerance, short acting "ATOM" channel opening eclampsia seizures respiratory depression Alprazolam, Triazolam, Oxazepam, Midalozam BARBITURATES DURation of Sedation, tolerance, barbiDURates & 1st line in neonates (PHENOBARBITAL) channel opening respiratory depression phenoBABYtal LEVETIRACETAM Unknown Partial & tonic-clonic Neuropsychiatric "How does he do the Symptoms Levitate trick?" TIGABINE & Tigabine partial seizUres Tigabine dizziness GABA Vigabatrin= refractory tiGABine & vi GABAtrin VIGABATRIN seizures Vigabatrin Vision loss 105CNS Pathologies RING ENHANCING LESIONS ABSCESS Causes: MAGIC DR. TOX! Most commonly caused by S. Aureus Metastasis Can be due to septic emboli (endocarditis): ABSCESS lookout for murmur + fever + neurologic Sx Glioblastoma Tx Drainage Abx Abscess, Aureus Infection CNS LYMPHOMA Demyelination PRIMARY CNS LYMPHOMA Radiation Can present similar to TOXO! TOXOPLASMOSIS If ring enhancing lesion in AIDS patient with CD4 countMotor Neuron Lesions UPPER MOTOR NEURON LESION (UMN) LOWER MOTOR NEURON LESION (LMN) "Everything UP!" "Everything LOWERED!" PRIMARY MOTOR CORTEX Spastic Flaccid & Fasciculations HYPERtonic HYPOtonic HYPERreflexic HYPOreflexic (+) UPgoing Babinski (-) DOWNgoing Babinski Diffuse atrophy Wasting atrophy STROKE BELL'S PALSY Lesion in the motor cortex MEDULLA Lesion in facial nucleus, CN VII Clinical Features: Clinical Features: Contralateral lower face weakness Ipsilateral full-sided facial weakness Forehead sparing (due to bilateral No forehead sparing innervation) ANTERIOR HORN MUSCLE GENERAL RULES TRIGEMINAL NEURALGIA 1. Lesions above pyramidal decussation, Motor deficit = CONTRALATERAL Excruciating pain lastingNeuromuscular Junction PRESYNAPTIC LAMBERT-EATON SYNDROME NEUROMUSCULAR Pre-synaptic channel defect BLOCKING AGENTS Associated with small cell lung cancer PRESYNAPTIC POSTSYNAPTIC Type II Hypersensitivity Weakness improves with muscle use constant BOTULISM Inhibits acetylcholine DEPOLARIZING agents ACh (ACh) release Heat-labile enterotoxin Depolarizing Succs (e.g., Succinylcholine) Sources: Honey (infant exposure) Constant/sustained stimulation (AP fires) tires out post- synaptic membrane nAChR MYASTHENIA GRAVIS 2 PHASES: Post-synaptic nAChR 1. Constant stimulation 2. Fade (desensitization) defect AEs: Fasciculations, Hyperkalemia, Malignant hyperthermia Type II hypersensitivity Thymoma association Weakness worsens with PRESYNAPTIC POSTSYNAPTIC continued muscle use MANAGEMENT: Pyridostigmine fade (acetylcholinesterase inhibitor) POSTSYNAPTIC Thymectomy NON-DEPOLARIZING agents TETANI (TETANUS) ALL Drugs ending in "-curium" Nicotinic receptor antagonists (no depolarization) Source: Open wounds Antidote: AChE inhibitors (increases ACh) Prevention: Tetanus vaccine Treatment: Antitoxin TETANOSPASMIN: spreads by retrograde axonal S transport to CNS spastic paralysis, lockjaw RABIES (RHABDOVIRUS) BOTULINUM Enveloped RNA virus Source: Honey, soil, canned foods Rabies, Rhabdo, Rod-shaped Infants ingest spores floppy baby syndrome Paralysis: Occurs in 20% Adults ingest preformed toxin foodborne illness Symptoms of Botulism): "Fifth gets stiff, glad Dysarthria Descending flaccid paralysis not M.A.D!" Dysphagia Deep tendon reflexes absent Diplopia Mental state changes Treatment: Human Botulinum Immunoglobulin Autonomic dysfunction Death bacteria Both TETANUS and BOTULINUM toxins cleave presynaptic Negri bodies in Purkinje cells TREATMENT: Rabies IVIG + SNARE proteins, preventing neurotransmitter release. (eosinophilic inclusion bodies) multiple course vaccine 110 TETANUS and RABIES travel to the CNS retrogradely via dynein motors and bind nicotinic ACh receptors. Clinical Neurology DERMATOMES REFLEXES C5-6: "Pick up sticks" = Biceps & Brachioradialis Reflex C7-8: "Lay them straight" = Triceps Reflex L1-2: "Testicles move" = Cremasteric Reflex L3-4: "Kick the door" = Patellar Reflex S1-2: "Buckle my shoe" = Achilles Reflex S3-4: "Winks galore" = Anal Wink Reflex MOVEMENT DISORDERS AKATHISIA: Restlessness (side effect of Parkinson's treatment) ATHETOSIS: Slow, snake-like movements (associated with Huntington's disease) REFLEX GRADING DYSTONIA: Sustained involuntary contractions (e.g., Torticollis) 1 2 3 4 HEMIBALLISMUS: Sudden flailing (damage to the subthalamic GRADE nucleus) ABSENT HYPOACTIVE NORMAL HYPERACTIVE CLONUS THINK going BALLIStic! PRIMITIVE REFLEXES ROOTING MORO SUCKING Disappears in months Disappears in months Disappears in months Abduction Extension of arms when Suckling reflex elicited upon pressing finger Stroking of cheek Tilts head toward stimuli startled followed by adduction on roof of mouth PALMAR BABINSKI GALANTO Disappears in 12 months Disappears in months Disappears in months Upturning of big toe w/ spreading of Stroking side of spine lateral Curling of fingers when palms are touched other toes upon plantar stimulation flexion toward stimuli 111Neurocutaneous Disorders STURGE-WEBER SYNDROME Stain (Port wine) Non-inherited vascular disorder due to Tram track sign (CT) White matter a somatic mutation in the GNAQ gene calcification GNAQ proteins are involved in nilateral leads to: stabilizing capillary webs etardation Raised ICP laucoma Epilepsy S.T.U.R.G.E. Epilepsy Intellectual WEB disability WEB of capillaries VON HIPPEL-LINDAU (VHL) DISEASE- Associated with: emangioblastoma VHL = letters = Chromosome ngiomatosis VHL codes for tumor suppressor proteins enal cell carcinoma Autosomal Dominant Leads to numerous tumors (both benign & malignant) heochromocytoma NEUROFIBROMAS TUBEROUS SCLEROSIS NEUROFIBROMATOSIS TYPE 1 (NF-1) Autosomal Dominant mutation in the genes: TSC 1 & TSC 2 Autosomal Dominant = letters Altered Harmartin (TSC 1) & Tuberin (TSC 2) work together as tumor NF-1 located on chromosome 17 suppressor proteins NEUROFIBROMATOSIS TYPE 2 (NF-2) Formation of benign tumors called Mutation on chromosome 22 (" Twenty 2-) 2 ears (bilateral acoustic schwannomas) amartoma ngiomyolipoma SYMPTOMS: itral regurgitation Tinnitus THINK! sh-leaf Hearing loss Vertigo "CAFE SPOT" habdomyoma ubers afé au lait spots aut somal Dominant A xillary freckling ental challenges strocytomas ibroma hagreen patch ye (Lisch nodules) S keletal Abnormalities TUBEROUS SCLEROSIS is the only P ositive Hx neurocutaneous disorder that ptical Tumors can cause Rhabdomyoma and 112 Renal Angiomyolipoma. Physiology of the Ear Auricle (pinna) Semicircular Different frequencies vibrate Tympanic Canal specific areas of the inner ear membrane Ossicles Vestibule External cochlea APEX of the cochlea responds to low auditory frequencies (near helicotrema) canal BASE of the cochlea responds to high frequencies Oval window The bones of the inner ear Pharyngotympanic are named after their shape: (eustachian) tube Malleus = Hammer Incus Anvil MIDDLE INTERNAL EXTERNAL (OUTER) EAR EAR (INNER) EAR Stapes = Stirrup SOUND Receives Amplifies Converts Electrochemical signal INFECTIONS OF THE EAR OTITIS MEDIA: Inflammation of the middle ear. OTITIS EXTERNA: Most commonly due to Haemophilus influenzae and Inflammation of the external auditory canal. Streptococcus pneumoniae. Most commonly due to Pseudomonas. Associated with Eustachian tube dysfunction. Associated with water exposure and trauma/occlusion. Usually seen in children under 2 years. HEARING LOSS NORMAL CONDUCTIVE SENSORINEURAL NOISE-RELATED HEARING LOSS: localizes to No Localizes to Sudden loud noises can produce hearing loss. WEBER unaffected localization affected ear Destruction of stereocilia cells in the Organ of Corti. ear RINNE AC BC AC BC AGE-RELATED HEARING LOSS (PRESBYCUSIS): Bilateral and symmetric sensorineural hearing loss. Rinne's and Weber's test are used to help AC Air Conduction Destruction of hair cells at the base of the cochlea. localize & classify potential hearing loss BC Bone Conduction VERTIGO CHOLESTEATOMA Sensation of spinning while standing still. Excess shedding of keratin in the middle ear. PERIPHERAL VERTIGO (inner ear pathologies): Can erode ossicles and cause conductive hearing loss. Example: Ménière disease Presents with painless otorrhea. Vertigo Tinnitus SYMPTOMS Sensorineural hearing loss BPPV is caused by displaced otoliths into the CENTRAL VERTIGO: Due to brainstem or cerebellar lesion semicircular canals. Epley maneuvers can treat them. 113Ophthalmology Lens REFRACTIVE ERRORS Anterior Chamber HYPEROPIA Macula Cornea "Farsightedness" Eye too short Increased risk of Glaucoma Zonular Corrected with convex lenses Fibres Optic Disc MYOPIA The point where the optic nerves converge to Conjunctiva: thin layer of exit the eye (optic disc) has no photoreceptors mucus that helps maintain and is known as the "blind spot"! moisture barrier CONJUNCTIVITIS: Inflammation of the conjunctiva Signs & Symptoms: RED EYES Allergic = bilateral itchy eyes Bacterial = purulent exudate, Tx with antibiotics "Shortsightedness" Viral = limited mucus discharge, swollen preauricular lymph nodes Eye too long (most common = adenovirus) Increased risk of Retinal Detachment NEONATAL CONJUNCTIVITIS Corrected with Concave lens GONOCOCCAL "Gonorrhoeae Goes early Chlamydia Comes later" ASTIGMATISM GONOCOCCAL CONJUNCTIVITIS presents DAY 0 - 5 Prophylaxis = erythromycin ointment Tx: Ceftriaxone CHLAMYDIA TRACHOMATIS Obligate intracellular ABC DK Africa, Blindness, Chronic infection Kids like Donkey Kong! Abnormal curvature of the Cornea FOLLICULAR CONJUNCTIVITIS NEONATAL CONJUNCTIVITIS presents Tx: Azithromycin OR Doxycycline DAY 5 11 PRESBYOPIA +/- Ceftriaxone (gonorrhea) Tx: Oral Erythromycin Age related decrease in 114 accommodation Aqueous Humor Production & Drainage TRABECULAR OUTFLOW (90%) Drainage through trabecular meshwork Aqueous humour Canal of Schlem episcleral vasculature is made in the ciliary bodies and provides nutrients & Drains into either: OUTFLOW maintains physiological pressure of the eyes UVEOSCLERAL OUTFLOW (10)% Drainage into Uvea & Sclera Episcleral IOP RANGES vein NORMAL EMERGENCY 11 21 35 Interscleral channel Schlemm's canal 0mmHg 10 20 30 Iris Trabecular meshwork sphincter Increased aqueous humor volume can lead to increased intraocular pressure.. 2 ways to combat this: Aqueous humor pathway Decrease INFLOW 1 via production in the ciliary bodies Anterior Lens Chamber Cornea REMEMBER the "ABC's"! = a2-agonists (i.e. brimonidine) = (i.e. timolol) c = Carbonic anhydrase-i (i.e. acetazolamide) Iridocorneal Increase OUTFLOW angle 2 via outflow tracts via Canal of Schlem: Contraction of sphincter pupillae (miosis) Suspensory moves iris increased outflow via M3 ligaments agonists (i.e. carbachol, pilocarpine) Ciliary Reabsorption through ciliary muscle muscle is increased by muscle relaxation via prostaglandins (i.e. latanoprost) 115Glaucoma & Uveitis Acute or chronic destruction of the optic nerve, with or without changes in intraocular pressure (IOP). OPEN ANGLE GLAUCOMA CUP-TO-DISC RATIO: Primary Cause: Unknown. RISK FACTORS: Age > 40 years Increased intraocular pressure (IOP) Myopia Diabetes Tx: Latanoprost & Bimatoprost Prostaglandin analogs are the preferred Normal = 0.3 first-line treatment. Glaucoma Cupping > 0.6 CLOSED ANGLE GLAUCOMA Primary Cause: Lens begins to obstruct aqueous flow. Fluid buildup pushes the iris against the cornea. Decreases trabecular outflow. Secondary Cause: Hypoxia from retinal disease. ACUTE: Symptoms: The Meadaches, alf-dilated pupils. Contraindication: Mydriatic agents like epinephrine. CHRONIC: Asymptomatic. Leads to damage of the optic nerve, causing vision loss. UVEITIS Contact lens- Inflammation affecting different parts of the uvea (iris, ciliary body, or choroid). related keratitis is associated with Pseudomonas ANTERIOR UVEITIS POSTERIOR UVEITIS infection. (Most Common Subtype) Iris Vitreous body AFFECTED AREAS Choroid Ciliary Body Retina HLA-B27 conditions. Commonly caused by infections: ETIOLOGIES Varicella Zoster Virus (VZV) Juvenile idiopathic arthritis. Rubella Rheumatoid arthritis. Toxoplasmosis RED EYES Painless CLINICAL SIGNS Hypopyon Scotoma with or without Dull pain flashes and floaters Lacrimation 116 Retinopathies NORMAL RETINA RETINAL VEIN OCCLUSION No exudates or hemorrhages. Compression of the retinal vein No vessels around the by nearby arterial atherosclerosis macula. causing venous engorgement Normal cup-to-disc leading to edema. ratio. Sudden and painless vision loss. No arteriovenous (AV) "BLOOD & retina. crossing. RETINITIS PIGMENTOSA AGE-RELATED MACULAR DEGENERATION Inherited progressive dystrophy of DRY (80%): the retinal pigment epithelium and Drusen deposition between Bruch's photoreceptors. membrane and retinal pigment epithelium Rhodopsin gene affected. leading to progressive loss of central Symptoms: Night blindness. vision. Tx: Antioxidants slow progression. WET (20%): Neovascularization leading to: More severe vision loss. PAPILLOEDEMA Large central blind spot. Optic disc swelling commonly due Treatment: Anti-VEGF. to increase in intracranial pressure DIABETIC RETINOPATHY Retinal damage due to chronic hyperglycemia. HYPERTENSIVE RETINOPATHY NON-PROLIFERATIVE: Damaged capillaries cause Chronic, poorly managed leading to macular edema. hypertension causing endothelial damage leads to fibrinoid necrosis PROLIFERATIVE: and retinal damage. Chronic hypoxia increases Signs: Cotton wool spots, AV VEGF production, leading to the nicking, microaneurysms. proliferation of new blood vessels and retinal detachment. Treatment: Anti-VEGF. RETINAL DETACHMENT Separation of the neurosensory layer CENTRAL RETINAL ARTERY from the epithelial layer. Symptoms: OCCLUSION Flashes and floaters. Generally unilateral and painless Vision loss described as sudden vision loss. "curtains being drawn down." Key Sign: CHERRY-RED SPOT. Management: Surgical emergency. 44 Congenital cataracts are LEUKOCORIA associated with galactokinase Loss of RED REFLEX is a RED flag and GALT deficiencies. In children Suspect Retinoblastoma. In adults Cataracts. 117Lysosomal Storage Disorders All Autosomal Recessive (except Fabry's disease & Hunter Syndrome, which are X-linked Recessive). Deficiency FABry's Alpha-galactosidase THINK FABulous Alpha Guy! Key Features: Key Features: D Peripheral neuropathy D Peripheral neuropathy D Developmental delay D Angiokeratomas Disease D Optic atrophy Disease X-linked recessive Niemann- GlucoCerebrosidase hingomyelinase "Auch" in Gaucher (crumpled Key Features: tissue appearance in Gaucher D Neurodegeneration cells) Hepatosplenomegaly (Niemann-BIG) Key Features: Cherry-red macula Disease D Hepatosplenomegaly D Avascular necrosis of the hip Disease "NO MAN PICKS HIS NOSE WITH HIS SPHINGER!" Deficiency in Tay-Sa osaminidase A Disease REMEMBER THE IN TAY WITH TWO AS GM2 ACCUMULATES. DASH (-) OF CHERRY" Key Features: The two diseases with dash in their name D Neurodegeneration D NO hepatosplenomegaly Niemann-Pick) both have a cherry-red macula. D Developmental delay D Cherry-red macula Hurler Hunter Inheritance: LINKED RECESSIVE "A HURLER IS A THROWER... Key Features: THROWING UP AND CAN'T SEE!" D Aggressive behavior (think hunters are aggressive!) Key Features: Clear eyes (hunters D Corneal clouding (can't see need clear vision because they are sick) for their prey!) D Developmental delay Syndrome D Stridor Syndrome MARKS THE SPOT!" 118 Ocular Physiology EXTRAOCULAR MUSCLES VITAMIN A Retinal can also be used for treating acne Trochlea Superior Rectus (Retinal) "retinAl nurtures the retinA, acts as an Antioxidant, and treats Acne" Superior Oblique DEFICIENCY EXCESS FUNCTIONS EFFECTS EFFECTS ACUTE: Medial Squamous Rectus Antioxidant ! Increased Intracranial Pressure Lateral Metaplasia (ICP) Rectus ! Nausea and vomiting Inferior Inferior oblique Rectus Component of CHRONIC: visual pigment Night Hair loss Blindness Hepatotoxicity/hepatomegaly MUSCLE ACTIONS (Rhodopsin) ! Increased ICP 1° 3° LR abduction MIOSIS Sphincter muscle MR abduction SR elevation intorsion adduction Iris Pupil Short ciliary IR depression extorsion adduction nerves extorsion elevation abduction SHORTENS so intorsion depression abduction Parasympathetic pupil diameter nerve Light Levels Constricts INNERVATION sec THINK! "LR6 SO4 R3" MYDRIASIS Radial muscle Long ciliary LR6 = Lateral Rectus (CN VI) nerves makes SO4 = Superior Oblique (CN IV) pupil diameter = Rest (CN III) Sympathetic LONGER nerve Light Levels PUPILLARY REFLEX Edinger-Westphal nuclei Pretectal nuclei Oculomotor 2) Action potential from Right eye reaches both Left & Right nerves 1b) Afferent signal Ciliary pretectal nuclei carried via optic ganglion nerves (CN II) 3) Pretectal nuclei stimulate both Edinger-Westphal nuclei 1a) Light shined on (even though light perceived in Right eye only only one eye) 4) Both Edinger Westphal nuclei generate action potential through Right & Left oculomotor nerves (CN III) bilateral pupillary constriction 119Pupillary Defects ARGYLL ROBERTSON PUPIL RELATIVE AFFERENT PUPILLARY DEFECT Characteristic Findings: Swinging Light Flashlight Test: Pupillary light-near dissociation lesion normal A complication of tertiary syphilis 1. Shine light on the a affected eye: a Small pupils (a) The pupil does not constrict fully (a) 2. Shine light on the b normal eye: The pupil accommodates b The pupil fully to near objects but does NOT constrict or constricts (b) constrict poorly to direct 3. Return the light to the light (b) affected eye quickly: The pupils dilate (c) Constrict when a target within reading distance is viewed (accommodation- Lesion: Afferent limb of the pupillary light reflex convergence is intact; c) (Cranial Nerve II) Causes: Asymmetric glaucoma Lesion: Pretectal nuclei Multiple sclerosis (MS) Causes: Optic nerve ischemia, neuritis, or compression Neurosyphilis (tabes dorsalis). Diabetic neuropathies. TRANSTENTORIAL (UNCAL) HERNIATION ARP (name of the diagnosis): Forward: Accommodation Reflex Present Clinical Features: Backward: Pupillary Reflex Absent (PRA) Increased Intracranial pressure uncal herniation Cranial Nerve III compression "Down and out" pupil + ptosis ADIE PUPIL Causes: Traumatic brain injury Clinical Features: Tumors Anisocoria Hemorrhage normal lesion Dilated and irregular a HORNER SYNDROME pupil (a) Lesion: Oculosympathetic pathway b Reacts sluggishly or has Causes: Anhidrosis no reactivity to light (b) Peripheral (T1 superior cervical ganglion) OR Central Clinical Lesion: Ciliary ganglion Cause: Idiopathic Triad 120 Miosis Ptosis Visual Field Defects VISUAL FIELDS CRISS-CROSS RULE: L R The nasal (medial) retina processes the lateral visual field. LAT MED MED LAT The temporal (lateral) retina processes the medial visual field. Visual field Site of lesion Causes defect LEFT EYE ANOPSIA Left optic nerve (CN II) Pupillary light reflex: Optic neuritis Absent when light is Central retinal artery flashed in eye occlusion Present when light is flashed in eye LEFT EYE HEMIANOPSIA Internal carotid artery Left temporal fibers aneurysm (expanding from optic nerve medially) BITEMPORAL Pituitary Adenoma HEMIANOPSIA Optic chiasm (mid- (begins as bitemporal superior sagittal lesion) quadrantanopia) Most common lesion! Craniopharyngioma (begins as bitemporal inferior quadrantanopia) RIGHT HOMONYMOUS If pupillary light reflex HEMIANOPSIA slightly suppressed Left optic tract or LGN Middle cerebral artery occlusion If pupillary light reflex RULES: present + Optic radiation RIGHT HOMONYMOUS 1. Left stays Left! SUPERIOR Left Meyer's Loops QUADRANTANOPIA Middle cerebral artery Left eye: Left (temporal) tract stays left or Temporal radiation occlusion Macular sparing Right eye: Left (nasal) tract stays left Temporal lobe tumor if lingual gyrus is preserved 2. Right stays Right! Left eye: Right (nasal) tract stays right RIGHT HOMONYMOUS Right eye: Right (temporal) tract stays INFERIOR Left Baum's Loop right QUADRANTANOPIA of parietal radiations Posterior cerebral artery Macular sparing 3. Low carries High! occlusion if cuneus gyrus Lower loop (Meyer's Loop) runs preserved through the temporal lobe Superior visual field (high) RIGHT HOMONYMOUS HEMIANOPSIA WITH 4. High carries Low! Primary visual cortex MACULAR SPARING Macular vision spared Posterior cerebral artery Upper loop (Baum's Loop) runs occlusion due to collateral blood through the parietal lobe Inferior supply from MCA visual field (low) 121122 References 1. McCrady, R. F.S.J., Jannetta, P.J., Casey, K.F., Marchan, E. 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