Pathology Flashcards
What is Brown-Sequard Syndrome?
Spinal Cord lesion affecting LMN
= Ipsilateral UMN paralysis loss of proprioception (touch + sensation)
Contralateral loss of pain and temperature, no reflex ( as pain crosses at entry deficit is on other side)
What happens to reflexes and muscle tone in an UMN lesion?
Paralysis (disrupted neurone pathway
But LMN pathway fine so exaggerated reflexes + tone= hyperreflexia, spastiparalysis
What is Electrophysiology used to diagnose?
Ulnar Neuropathy- cell sensory body in DRG alive but anterior horns + regions to spinal chord die.
Left with sensory + motor response from ulnar nerve but no action
What is Electromyography (EMG) used to diagnose?
NMD (tight relationship between fibres in motor units lost)= Jiter
eg./ Myathesthenia Gravis (autoimmune) antibodies to post synaptic ACh receptor = weakness and fatigue of facial muscles (+ ptosis + diplopia) treat via acetylcholinesterase inhibitor + immunosuppression
What is Electroencephalogram used to diagnose?
Looks at electrical activity within the brain
eg./ Ambulatory sleep study (over day + night)
Video telemetery- epilepsy
Encephalopathy, altered consciousness states
What happens to sensation if you damage the dorsal column?
Loose noxious mechanoreceptors on ipsiliateral side (hasn’t crossed yet)
What happens to sensation if get a lesion on anterolateral spinothalamic tract?
loose thermorecptive + nociceptive on contralateral side (cross immediately)
What is Right-Left Agnosia?
Lesion-Hemisensory neglect- can perceive sensations but can’t comprehend other side of the body
What is Acalculia?
Dominant lobe lesion- can’t count, write etc
What is Agraphia?
Less dominant lobe lesion- artistic + musical affects
What is Aphasia? What are the 2 different subtypes?
Problem with speech due to 1+ damaged areas in the brain
- Brocas Aphasia- Frontal lobe damage- understand + aware but miss small words + weakness/ paralysis of one side (motor cortex here)
- Wernicks Aphasia- Temporal Lobe Damage- fluent but meaningless speech, not aware NO paralysis
What are the 3 types of fibres found in white matter? What areas do they connect?
- Commisural Fibres- One hemisphere to another eg./ corpus callous
- Associated Fibres- Different lobes in 1 hemisphere (long/ short)
- Projection Fibres- Up (sensory) + Down (motor) through internal capsule (fibres passing to and from the cerebral cortex)
What is the basal ganglia? What is it made up of? What is its function?
A collection of neuronal cell bodies deep in cerebral hemispheres.
Composed of-
1. Caudate Nucelus
2. Lentiform Nucleus (putamen + globus pallidus)
3. Substantia Nigra (midbrain)
Regulates initiation and termination of movement (inertia)
Extrapyramidal- control of motor system
What kind of pathology is found in the basal ganglia?
Parkinsons
Chorea
Athetosis
What is hydrocephalus?
Excessive cerebrospinal fluid volume in IV spaces= dilation of ventricles + a wide range of symtoms
What is communicating hydrocephalus?
Non-obstructive
CSF production > CSF absorption OR CSF>
Uniform dilation= Inc ICP
Cause- Infection eg./ bacterial meningitis,
Subarachnoid haemorrhage, post op eg./ tumour gunge blocks, head trauma, choroid plexus papilloma (rare)
A neurological condition presents with-
Increased head circumference in neonates
and papillodema- diplopia/blurred vision, gout disturbance, 6th CN palsy, neck pain + upwards gaze difficulty in the rest of the population.
What is this pathology? How would you go about investigating and treating it?
Communicating (non-obstructive) hydrocephalus
6th nerve as passes through subarachnoid space
neck pain- tonsillar herniation
Investigate via Ct (asses ventricular size- will be dilated, 3rd ventricle ballooned), MRI, Ultrasonography in infants.
Treat via external ventricular drain (3 way tap into left ventricle (high infection risk) + mannitol (osmotic diuretic)/ communicating shunt
What in non- communicating hydrocephalus?
Obstruction
eg./ Aqueductal stenosis (kids, foramen of munro); tumours cancers and masses; cysts/ infection; haemorrhage/ haemotoma; Interventricular bleed, Spina Bifida Cystica.
Headaches in the morning are common
Treat via shunt, remove lesion (eg./ pineal tumour, ependyma, colloid cyst), 3rd ventriculostomy- hole in 3rd ventricle fluid bypasses cerebral aqueduct
What is normal pressure hydrocephalus?
Communicating Hydrocephalus on MRI. Normal opening pressure dementia like syndrome reversible with treatment via VP shunt (pressure is normal so hard to know how much to remove)
Hakims Triad- Wet, wobbly (gait) + wacky (dementia)
What clinical suspicion of disease would a lumbar puncture be required for? What are contraindications for carrying it out?
To Investigate- Meningitis Subarachnoid Haemorrhage (bilirubin levels) Meningioencephalitis (WBC) Malignancy (cytology) Infusion of drugs/ contrast Contraindications- Cardiac/ respiratory instability Localised skin/ soft tissue infection Inc ICP (head CT first) Chiari Malformation (tonsillar herniation)
how is a lumbar puncture carried out?
- Povidone- Iodine + wand + fenestrations
- Anasthetic eg./ lidocaine
- Spinal needle thorugh L3-4/4-5
- manometer, stopcock + tubing
Through erector spinal + ligament flavulum + dura (double pop)
Collect 3 tubes (Culture + gram, glucose + protein, cell count/ differential)
What are the complications of a lumbar puncture?
Spinal headache/ blackout
Epidermal occlusion cyst
Herniation- intubate, IV saline, bed back to 30-40
Nerve Trauma- feels like electric shock to Pt, withdraw needle and try again, if long shock give corticosteroids and do nerve conduction studies
What can cause bilateral hippocampal damage and what affect can this have?
Herpes Simplex
Long term memory before the damage will be intact + immediate sensory + reflective intact (as they don’t require retention through papez circuit) BUT loose ability to form new long term memories
How is amnesia caused? What are the 2 subdivisions?
Caused by disruption of reverberating neuronal circuit eg./ by head injury/ infection
1. Anterograde Amnesia- Inability to recall events AFTER incident (shot lived/ permanent)
2. Reterograde Amnesia- Can’t remember events BEFORE injury (can recall old)
Usually both present together.
If thalamus damaged but hippocampus intact get retrograde only (thalamus needed to search existing memory bank)
What is Korsakoffs Syndrome?
Chronic Alcoholism (dec in Vitb1)- damages limbic system (reduced ability to consolidate memories)
What is Alzthehiemers?
Severe loss of cholinergic neurones (including in hippocampus)= memory loss (anti-cholinesterase improve but still underlying degeneration)
A viral infection can cause damage to sensory inputs (proprioception) at spinal level. What would happen as a result of this?
Neurones in DRG die (don’t regenerate) loss of body in space- rely on visual system to provide feedback
What are the clinical signs of an UMN lesion? Why do these occur?
Normally synapse with LMN to regulate ⍺motor-neurone activity
lesions- spasticity (continuous contraction causes stiffness/ tightness), paralysis, transient, brisk reflexes, Babinski sign
What is the motor functionality difference between the corticospinal tract vs rubrospinal tract vs reticulospinal tract? How will this affect a clinical signs of a lesion?
Corticospinal is lateral- descending control of ‘skilled’ motor to extremities so will get paresis (weakness) NOT paralysis with lesion here.
Rubrospinal is anterior to cortispinal- descending facilitate flexors + inhibit extensors (balance control) fine tuning and fraction (1 joint only movement) affected.
Reticulspinal is anterior- descending cortical control of voluntary motor function
What is spinal shock?
Damage to spine- firing at abnormal rates= trauma to spinal chord (loss of brain-muscle connections)
Loose sensation, bowel, bladder + sexual regualation (autonomic)
Reflexes return but exaggerated + clonus. Loose excitation above lesion but works below
How does a LMN lesion present?
Nerve and neuronal cell body destroyed- paralysis + NO reflexes
Arflexia, Flaccid paralysis
How do epileptic seizures occur?
Abnormal firing of high frequency APs creates a wave across the cortex-marches- fingers- arms- face etc
How does UMN Syndrome occur?
- Cortical Damage= hypotonia (spinal shock), Babinski sign
- Removal or cortical suppressive influences (spared circuits strengthen/ make new connections)= spasticity (inc muscle tone= colnus)
- Loss of fine finger movements
What is Parkinsons Disease?
degeneration of neurones in the substantial migration + loss of their excitadory (dopaminergic) input of corpus stratum
=loss of activation of focused motor activites, hypokinesia (rigidity, tremors, slow, difficulty make voluntary movements)
What is Huntingtons Disease?
Hereditary, rare, progressive + fatal
Loss of caudate, putamen + globus pallid us
= hyperkinesia, dementia, personality disorder, chorea (spontaneous, rapid flicks)
What are names of the congenital condition where the neurotube doesn’t close?
Exencephaly- anterior neuropore fails to close
Craniochischisis- fails to close along neuroaxis
Encephalocoele
Spina Bifida- caudal tube fails to close
What is Spina Bifida? What are the 2 subclassifications?
Defective closure of the neural tube at the caudal end so vertebral arches don’t fuse
1. Occulta- Failure of 1/2 of arches to fuse (L5 + 6 most common) healthy clinically: small tuft of hair at site. Diastematomyelial (split chord)
2.Cystica- Protrusion of spinal chord +/- meninges through defect in vertebral arches
A- +meningocele- mildest, meninges + CSF
B- + meningomyelocle- nerve roots +/- spinal chord (loose sensation of muscle, paralysis)
C- Myeloschisis (spinal chord open)
What congenital defect does ZIKA virus cause?
Microephaly- Imparement/ motor delay/ seizures/ balance + coordination problems
Has a transmitter
- Synthesis + packaging of neurotransmitter in presynaptic terminals
- Na+ AP invades terminal
- Activates V gated Ca channels eg./ spider toxins block all here= paralysis
- Triggers Ca dependent exocytosis of pre-packaged vesicles in transmitter eg./B.toxin blocks-can stop spasm
- Transmitter diffuses across cleft and binds to ionitrophic +/ metabolic receptors
- Presynaptic autoreceptors inhibit further transmitter release eg./ activate presynaptic inhibitory receptors
- Transmitter is usually inactivated by extracellular breakdown
- Transmitter metabolised within cells
Is acetylcholine a neurotransmitter?
Yes
What neurotransmitters are monoamines? What is their pharmacological use?
- Noradrenaline-antidepressants
- Dopamine
- Seratonin- antidepressants, migranes
What neurotransmitters are amino acids? What is their pharmacological use?
- Glutamate (fast EPSP)
- GABA (Fast IPSP)- antiepilespy/anxiety
- Glyceine (fast IPSP)
What neurotransmitters are purines?
ATP
Adenosine
What neurotransmitters are neuropeptides?
Endorphins
CCK
Substance P
Why is Nitride Oxide an unorthodox neurotransmitter?
It is not packaged into vesicles
What is the function of Dopamine + how does this relate to Parkinsons disease?
Dopamine has 5 G-Protein coupled receptors (can’t invoke EPSP/IPSP) so has many effects in different regions
Parkisons- degeneration of dopamine in nigrostriatal pathway (S.N- C.S)= stiffness, slow movements, change in posture + tremor
Action-
Brainstem- nausea/ vomit
Basal Ganglia- voluntary movement
Limbic + Frontal- emotion/ rewards
Can’t give dopamine injections as doesn’t cross BBB so need to give Dopamine precursor (make remaining cells produce more) eg./ levodopa + dopa-decarboxylase inhibitor
Dopamine Agonist eg./ ERGOTS (dirty- fibrosis of lung, heart + renal) NONERGOT
Enzyme inhibitors eg./ Peripheral AAD Inhibitors, MAO B Inhibitors (antidepressants); COMT Inhibitors (dec metabolism of Dopamine)
These help tremor, rigidity + bradykinesia but worsen psychosis + nausea
Dopamine antagonist (worsen parkinson’s but stop nausea/ vomitting)
Anticholinergics (tremor)
What is insomnia?
Chronic inability to obtain the necessary amount/ quality of sleep to maintain adequate daytime behaviour
A- Chronic, primary, no cause
B- Temporary, secondary to pain physical/ emotional
NOTE: very difficult to see on electro encephalogram (EEG)
Treat with Benzodiazepines (addictive)
What is somnambulism?
Sleep walking- delta sleep (S4) no recollection
What is Narcolepsy?
Directly into REM, accidental risk. Due to innappropriate melatonin release from hypothalamus
How can you damage CN1?
Fracture to cribriform plate may tear olfactory nerve fibres
How can you damage CN2?
Optic
Papillodema- Inc CSF, blood can go out but not back (pools in optic cup)= damage to nerve/ chasm/ tract
Vision Problems eg./ short vision= demyelination of nerve
Optic Neuritis- Demyelination of optic nerve giving monocular vision loss, pain on movement, reduced visual acuity/ colour vision, optic disk swollen (MS association)
How can you damage CN3, 4 + 6?
Occulomotor, Trochlear + Abducent
Cocaine, Youth, Dim Light (parasympathetic nerve damage), Anxiety, Brain Death, Anxiety/ Excitement, Old Age, Bright Light (sympathetic chain damage), opiate overdose, Horners Syndrome, Isolated/ Combination Nerve Palsy, Diplopia die to muscle deviations,Supranuclear Nerve Palsy (eg./ parksinsons)
How can you damage CN5?
Trigeminal
Trigeminal Neuralgia- Paroxysmal attacks of pain, triggers, middle aged/ older due to compression of nerve in posterior fossa.
Treat with carbamazepine/ surgery if resistent
How do you damage CN 7?
Facial
Long path through bone so injury most common
Bells Palsy- unilateral facial weakness, idiopathic, LMN (loose forehead movement), preceded by pain in ear, eye closure affected (risk of corneal damage). Treat with steroids _ lubricant
How do you damage CN8?
Vestibulocochlear
Vestibular Neuronitis- sudden onset of disabling vertigo + vomit, gradual recovery ( no known cause)
Nystagmus- congenital/ visual/ peripheral/ brainstem/ cerebellar/ toxins (alcohol, phenytonin- anti epileptic)
How do you damage CN 9+10?
Glossopharyngeal + Vagus Bulbar Palsy (LMN)- polio, tumours, syphilis= dysarthria (slurring), dysphagia, dysphonea, wasted fasciculated tongue
How do you damage CN 12?
Tonsillectomy
Tip deviates to AFFECTED side
What happens when Cerebral Perfusion Pressure >150mmHg?
Autoregulation fails (50-150mmHg) so contraction of arterioles no longer sufficient to maintain constant blood flow to brain.
= Hypertensive Crisis- vasogenic oedema
eg./ toxins eg./ CO2, first 4-5 days of head trauma
What are the 3 different types of cerebral oedema?
- Vasogenic Edema- Extacellular (Inc capillary permeability) Fluid is plasma (protein) infiltrate due to tumour, infarct, abscess, trauma. Treat via mannitol + steriods
- Cytotoxic-Intracellular Fluid in water + sodium due to failure of membrane transport. Treat via mannitol
- Interstitual- Hydrocephalus impared CSF absorption (obstructing/ non-obstructing)
What is persistent vegetative state?
Brain stem recovers to a considerable extent but no recovery of cortical function (lost content of consciousness) but not ascending so awake
What is locked-in syndrome?
Total paralysis below 3rd nerve nuclei ( open eyes, look up and down, smell) Damage to front of pons (stroke in basilar artery) where pyramidal tracts cross so can’t move arms/legs
How do you treat a Pt in coma/ persistent vegetative state/ locked-in syndrome?
Airways Breathing Circulation Bloods, BP, Pulse, Temp, IV Acsess Meningitis? GCS CN Tests Motor Function- tone, reflex
A Pt presents in a coma GCS
Toxicology Blood Sugar + Electrolytes Heaptic + Renal Function Acid-Base Assesment + Blood Gasses BP CO (poisioning) Could be- DKa, Metabolic (acidosis/ alkalosis), Alcohol/ Drug Overdose, Epilepsy, Infection, Medical (Diabetes, sepsis, renal/ hepatic failure)
A Pt presents in a coma GCS
CT Head Scan LP- Appearance, Cell Count, Glucose levels Could be- Meningism Subarachnoid Haemorrhage Encephalitis
A Pt presents ina coma, GCS
CT/MRI
Metabolic Screen
Lumbar Puncture
Electro Encephalogram (EEG)
What group of individuals is at the highest risk of coma? What is the curators marker for a ‘good outcome’ if Pt wakes before?
Young as brain hasn’t shrunk yet
6 hrs is marker for ‘good outcome’
What are the 4 types of head injury and how are they managed?
- Diffuse Axonal Injury (multiple lesions, accel/deceleration trauma, cause of PVS)
- Contusion
- Intracerebral Haematoma
- Extracerebral Haematoma
- extradural= convex on CT
- subdural= concave/ convex on CT
Treat via ABC, CT, stablize cervical spine, intubate + ventilate (if GCS
What is a stroke and what are the 2 types?
Sudden onset of focal/global neurological symptoms lasting >24hrs
- Ischaemic- Atherothromboembolism (carotids), small vessel occlusion (lacune), cardiac emboli (AF, endocarditis, MI)
- Haemorrhagic- Intracerebral Haemorrhage, subarachnoid haemorrhage, AV malformation
What is different about strokes in young people?
Sudden BP drop
eg./ boundary/watershed stroke (area between 2 vascular beds), carotid artery dissection , subarachnoid.haem, thrombophilia
What is the pathology behind a stroke?
Failure of cerebral BF- Degree of Hypoxia (brain doesn’t have energy supply)- Prolonged- Anoxia (no 02)- Infarct (cell death at 10mL/100gtissue/min) - Necrosis= oedema/ swelling/ secondary haemorrhage