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By: Daniyal Sithawalla 1Intended Learning Outcomes(ILOs) ● Describe thestructure and function of the ear, and how sound waves are converted into sound. ● Describe structures in thenose and throat that can affect the ear. ● Identify the anatomy of the vestibular system and explain its function. ● Outline and explain theneuronal pathways between the ear and theauditory areas of the cerebral hemispheres. ● Classify the types of hearing loss, how to differentiate between them, and how they are investigated (includeotoacousticemissions, otoscope, tuning fork, puretoneaudiogram, tympanogram). ● Discuss the key social and psychological consequences of hearing loss. ● Identify the various types of paroxysmal neurological events and their corresponding pathological features. ● Differentiatebetween thevarious types of seizures and their causes (such as trauma and infection, and geneticepilepsy). ● Recap fromweek 1 the normal electrophysiological properties of neurons and explain how these properties are altered in epilepsy (including the cellularand molecular mechanisms of epileptogenesis) ● Describe therole of neurological structures in thegeneration and propagation of seizures. ● Summarisethe pharmacological treatment options forepilepsy, including themechanisms of action, and evaluatethe efficacy and side effects of different antiseizure drugs and understand the principles of drug selection forindividual patients. ● Recognise the impact of epilepsy on behaviour, cognition, and mood. ● Assess thepsychological and social challenges faced by individuals with epilepsy and the importanceof a multidisciplinary approach to management.Sound A higheramplitude means a louder sound (measured in dB) A higherfrequency of oscillations means a higher pitch (measured in Hz)The Ear The human earcan conduct sound in the ranges of 20-20,000 Hz As we age the upper limit decreases to around 15-17,000 Most sensitive between 500-4,000 Anatomically the ear is split into 3 sections; external, middle and innerHearing Range: 20-20000Hz Speech: 200 - 500Hz As you get olderyou stop hearing the higher frequency The air pressure in the middle ear should be of the same pressure as atmosphere as that is when it will vibrate the best and produce best sound. What isthe purpose of waxin the ear: It is for waterproofingof the skin ofthe ear canalOuter ear Auricle/Pinna collects sound waves Funnels into External Auditory meatus Sound waves of around 3,000 Hz are boosted in sound pressure 30-100*, thus boosting their amplitude The difference in sound arrival time between the ears allows us to localise sound in the horizontal plane Auricle/Pinna can funnelhigh frequency sounds coming from above better, allowing for verticalTympanic membrane The tympanic membrane actsas the border between the external and middle ear Made of 3 layers, outer epithelial, middle fibrous and inner mucosal Function is to vibrate and transmit sound to middle earMiddle Ear From tympanic membrane to oval window Malleus>Incus>Stapes Functions to amplify and transmit vibrations from tympanic membraneto oval window Converts airborne sound waves in theexternal ear into fluid vibrations for inner ear Pressureexerted at ovalwindow is 20 times greater than at tympanic membraneSide characters of middle ear Eustachian tube drains fluid from middle ear and balances pressure each side of tympanic membrane Shorter wider and more horizontal in childrenSide characters of Middle ear Tensor tympani (V3 trigeminal) and Stapedius (CNVII) contract in response to loud sound, reduces by approx 20dB. Tensor tympani pulls malleus away from tympanic membrane Stapedius pulls stapes from Oval window · Contraction of thesemusclescauses the chain of ossiclesto become more rigid, andsoundconductiontotheinner is greatly diminished. · The onsetof a loudsound triggersa neuralresponse called the attenuationreflex. · Soundattenuation is much greater at lower frequencies thanat high frequencies. · The automatic contraction ofthese muscles occursa few microseconds after a loud noise, and so doesn’tprovideprotection against sudden loud noises.Internal ear Contains structures responsible for hearing and balance Cochlea – part ofthe auditory system. Labyrinth – not part of the auditorysystem. This forms part ofthe vestibular system, which helps maintain the body’sequilibrium (balance). Bony labyrinth- Cochlea, semicircular canals and vestibule (part of which part of which bone?) Membranous labyrinth- cochlear duct, semi-circular ducts, utricle and the sacculeCochlea and hearing 3 fluid filled sections ● Scala vestibuli on top- Perilymph ● Scala media- Endolymph ● Scala tympani- Perilymph Endolymph- High potassium, low sodium Perilymph-Lowpotassium, high sodium· Reissner’s membraneseparatesthe scala vestibuli and the scala media. · Basilar membrane separatesthe scala tympani and the scala media. · Sitting on thebasilar membraneisthe organ of Corti, which contains auditory receptor neurons; hanging overthisorgan isthetectorial membrane. · Attheapex of the cochlea, thescala media isclosed off, and the scala tympanibecomes continuous with the scala vestibuleat a holein themembranescalled the helicotrema. This allowsthe perilymph in these two scaleto mix. · Atthebase ofthecochlea, the scala vestibuli meets theoval window and the scala tympani meets the roundwindow.Sound hits When the footplate of the stapes hits the oval window, the fluid inside the cochlea move The movement of fluid causes displacement of the basilar membrane At the base membrane is wider and stiffer,so high frequency waves needed At apex it is thin and loose, so can be displaced by low frequency Helicotrema is point where vestibuli and tympani are togetherOrgans of Corti Stimulated by vibration of basilar membrane Made of hair cells (mechanosensory hair cells)- on your tectorial membrane ● Each hair cell contains multiplestereocilia, singlekinocilium(tallest sterocilium) ○ The longer stereocilia are arranged closer to kinocilia; shorter further away ● Haircells embedded in gelatinous layer (otolithic membrane)Organs of Corti ● Inner hair cells- 3500(1 row)cannot be regenerated- damage is permanent ○ Innervated by~20 spiral ganglion cells (type1) ○ In charge of auditory transduction ● Outer haircells ~12000 (3-5 rows) ○ Modulate sound with prestin ○ Motility created bymicrotubules and microfilaments ○ Respond to signals from brain- to contract orstretch according to signals ○ Change the stiffness of the basilar membrane → amplifiesor dullssensory input (depending on the amplitude of the signal ● Tectorial membrane- wherestereocilia are embeddedThese Hair Cells: ○ Translate mechanical signals to electrochemical signals) ○ Each hair cell has 30-300 setreocilia at apical end ○ Tip link attaches the membrane of particular stereocilium to a mechanically gated K+ channel in another longer stereocilium in nextrow ○ Different regions ofthe corti, tuned to different frequencies ○ Specific frequencies cause stereocilium of specific hair cells to bend, depolarise, convert sound waves to electrical impulsesAuditory Transduction 1. Basilar membrane vibrates 1. Innerhaircells innervated by sensory nerve fibres → auditory transduction 2. Outer haircells innervated bymotor nervefibres →carry signalsfrom brain, contractin response to auditorytransduction 3. Changethe stiffnessof basilarmembrane to intensify/minimizethe signal 2. Pushes organ ofcorti+ hair cellsagainst tectorial membrane (located in scala media) 3. Shorter stereocilia bendtowards thelonger stereocilia→activate the tiplink (protein filament) → open potassiumchannel 4. K+ concentrationintheendolymphgreater thaninthe cell →K+entersthe hair cell atthe apicalend →cellmembrane depolarises 5. Depolarisation of the presynaptic membane → voltage gated calciumchannels open→calcium ions enter thecells→trigger glutamic vesicles in cytoplasm toreleaseglutamateinto synaptic space 6. Dendrites of neurons that formtheauditory nerveareexcited by glutamateand depolarise → electricalimpulseto brainAuditory pathway Lots of crossover means that lesion on one side will not cause hearing loss unless it’s at 1st neuron E.COLI MA or ECO LIMA 1. Ear receptors (Hair cells) in Cochlea and Eighth Cranial nerve (CN VIII) 2. Cochlear nucleus 3. Superior Olivary nucleus 4. Lateral lemniscus 5. Inferior colliculus 6. Medial geniculate nucleus 7. Auditory cortex Testing for hearing Audiogram Pure tone audiometry- conventional ● Measuresbetween 250Hz to 8000Hz ● Pure tone average should be 25 dB or below ○ 20-40: Mild hearing loss ○ 41-70: Moderate hearing loss ○ 71–95: Severe hearing loss ○ 95: Profound hearing loss Types of hearing loss: ● Conductive hearing loss: Difference of >10 dB between bone air and air conduction ● Sensorineural hearing loss: When both air and both conduction is >20 dB ● Mixed hearing loss: when both air and bone conduction > 20 dB, 15 dB or more difference where bone conduction is greater and airCauses of Each Conductive hearing impairment- smth wrong w yourovalwindow i.eblockage Sensory-neuralhearing impairment- smth wrong w chochlear, cochlearnerve, brain Sensorineural Conductive Presbycusis(agerelated hearing loss) Otitismedia with effusion Noiseinduced (damage to hair cells) Impacted earwax Menieres(vertigo,tinnitus,and hearing loss) Perforated eardrum Ototoxic drugs Anything stuck in your ear Malignancy Weber- tells youwhetheritis leftor right Webers and Rinnes Rinne- Sensorineural orConductive Rinne Test Weber Test Normal Air conduction > bone conduction Midline bilaterally Conductive hearing loss Bone conduction > air conduction in Lateralises to affected ear affected ear Sensorineural hearing loss Air conduction > bone conduction in Lateralises to unaffected ear unaffected earHearing Loss Examples Normal HearingX,O means Bone Conduction [ ] means Air Conduction Sensorineural Hearing LossConductive Hearing LossMixed Hearing LossTympanostomy It tests how stiff the tympanic membrane is, where a microphone tests the response of the ear drum to pressure exerted on it. ● A – high-peak tympanogram→usually indicates normality andsignificantly decreasetheprobability of middle-eareffusionas thecause ofhearing loss ● B – highest probability of the presenceof middle-ear effusion/tympanic membraneperforation (both ofwhich arelikely to causesome degreeof hearing loss) ● C – peak shiftedtowards negativepressure – low probability ofmiddle-earfluid and associated hearing lossOtoacoustic Emissions (OAE) · Thesecan bemeasured with microphonesinserted into theexternalauditory canal. · The emissionsmay bespontaneousor evokedwith sound stimulation. · The presenceof OAEs indicates thattheouter hair cells of the organ of Cortiare intact andcanbe used toassessauditory thresholds andtodistinguishsensory fromneural hearing losses. - This testisnow standardtotest for new bornsense of hearing. Automated auditory brainstem response (ABR) ● Used when infants fail OAE more than twice. ● Measures cochlear response ● Pass/fail result (fail implies a hearing level worse than 40 dB) ● Can be performed on each ear individually and on a child of any age (best when child is asleep because motion artifacts interfere with results)Vestibular System Vestibular apparatus: vestibule and semicircular canals Vestibulelocated between semi circular canals and thecochlea ● Contains the utricles, saccules and equilibriumreceptors called macula (wherehair cells are found) ○ Saccule: Continuous with cochlear duct anteriorly, for vertical acceleration (lift) ○ Utricle: Continuous with semi circular ducts posteriorly, horizontal acceleration (e.g car lurching forward) ● Otolith organs formstatic system and detect linear acceleration (otolith organs, utricle and saccule ● Semi-circular canals formthedynamic system and detect angular accelerationVestibular System Anterior Canal- YES movement/ Up n Down Posterior Canal - Ear to Shoulder Movement Horizontal Canal- NO movement / Looking left to right or vice versa Once more ● Utricle-Horizontal movement ● Saccule-Vertical movementVestibular Reflexes Vestibulo-ocular reflex Response to head movement resulting in movement of eyeto prevent retinal slip and stabilises images to retina. ● Mediated by cerebellum Vestibolo-Cervical reflex Postural adjustments of head Vestibulo-Spinal relex Postural adjustments of bodyPathophysiology associated with vestibular system ● Meniere’s Disease – increase in endolymph pressure → disrupts signal transduction → tinnitus, nausea, spontaneous nystagmus ○ Treatment is not very satisfactory e.g. diuretics ● Benign paroxysmal positional vertigo (BPPV) → dislodged bits of otolith stimulates the cupula in the posterior semicircular canal → vertigo → Epley maneuver attempts to nudge them back to the vestibule ● Motion sickness → humans are not designed for transportation → mismatch from different sensory modalities and with what the rest of the brain expects to happen ● Alcohol intoxication → changes endolymph pressure and inhibit cerebellum functionNystagmus- Involuntarily eye movement ● Eye will track an object until it moves out of visual field → retina shoots backto centre ○ Slow phase:Eye is tracking object- mediated byvestibulo-occular pathway ○ Fast phase: Eye flicks back to the centre, triggered by cerebral cortex To test for it we carry out the caloric test : Warm/Cold water is squirted into the ear→ COWS - COLD water mimics aheadturn to thecontralateral side. - Botheyesturntothesame (ipsilateral) ear, with the horizontalnystagmus to the(quickhorizontal eye movements) to theOPPOSITE (contralateral) ear. - WARMwater mimics aheadturnto theipsilateral side. - Botheyesturntotheopposite (contralateral) ear, with the horizontalnystagmus to the(quick horizontaleye movements) to the SAME(ipsilateral)ear.Aphasia · Aphasiais the inability to speak, writeor understand the writtenor spoken word, which resultsfrom a lesioninthe brain. · Sounds are identified and comprehended as meaningful wordsby Wernicke’sareafound on the superior temporal gyrus. · Sequencesof soundsto produce words and sentencesare formulated in Broca’s areawhichlies in the inferior frontal gyrus. · The Wernicke’sareaandtheBroca’s areacommunicate via the arcuate fasciculus.Aphasia ● Sensory/Receptor Aphasia - WERNICKE’S WAFFLER ○ Occurs form a lesion to the inWernicke’s area. ○ Thereis fluency of language but words aremuddled. [They waffle] ○ They also have issues understanding what is said sometimes ● Motor/Expressive Aphasia - B-B-B-BROCA (like an engine) ○ Occurs form a lesion to the inBroca’s area. ○ Thereis reduced speech fluency with relatively preserved comprehension. ● Conductive Aphasia ○ Occurs form a lesion to the in arcuate fasciculus. Theseare theassociation (whitematter)fibres connecting the Wernicke’s area and the Broca’s area. ○ Theoutput of speech is fluent but paraphrasic, comprehension ofspoken language is intact, and repetition is severely impaired/they can't repeat words. ○ Naming and writing are also impaired. ○ Reading aloud is impaired,but reading comprehension is preserved. ● Global/Central Aphasia ○ This means the combination oftheexpressiveproblems of Broca’s aphasia and theloss of comprehension of Wernicke’s with loss ofboth language production and understanding.Otitis media - an inflammatory condition of the middle ear Risk factorsinclude; being a child, genetic differencesin eustachian tube, smoking, allergic rhinitis,tonsillitis, Working mother, Bottle feeding Most likelycaused by Streptococcuspneumoniase, Haemophilus influenzae, Morexilla catarrhalis Treatment Amoxicillin is a firstlinedrug if after 72 hoursif the infection has notsettled down. Recurrent AcuteOtitis Media: More than threeepisodes within6 months or four episodeswithin12months. - Antibiotic prophylaxis can reduce recurrences Otitis mediawitheffusion: fluidis present in the middleearforan extendedperiodof 3 months andinthe absenceof signs andsymptomsof infection. · A grommet (tympanostomy tube) is a tubethatis inserted ·Cochlea implantation and hearing aids Cochlea implantation is recommended in people with profound sensorineural hearing loss Stimulates electrical impulses directly onto nerve ● Pre-lingual- give before age of 4, if given around 2-3 they will develop normal hearingby 5 ● Post lingual in adults, after period of neuroplasticity cochlear implantation willnot improve hearingor speech Hearing aids amplify sounds of frequencies useful to us insteadHonestly just read Yaffa’s for BSS trust me alot of BSS which came out last year was in Yaffa’s. I know its annoyingto learn but try ur best. For what its worth it gets you the marks :)Answer: EAnswer: AAnswer: CSeizures What are seizures: Transient occurrence of signs and symptoms dueto excessive or synchronous neuronal activity within the brain. They can be classified into · Generalised Seizure – involves the entirecerebral cortex of both hemispheres. · Focal/Partial Seizure – involves onlya localised areaof the cortex, butitcan spread from one hemisphereto both - Can be subcategorised in to focal aware and unaware seizures. · In both cases, the neurons within theaffected areas firewith a synchrony that never occurs duringnormal behaviour. This is why seizures are usuallyaccompanied byvery large EEG (electroencephalogram) patterns.Causes of Seziures- VITAMIN D • VascularCauses– acute ischaemic strokes,intracerebralhaemorrhage, hypertension, eclampsia • Infective Causes – meningitis, encephalitis(infection of brain tissue), brain abscess • Trauma – extraduralhaematoma or subduralhaematoma • Autoimmune Causes – vasculitis, MS • Metabolic Causes – hypoglycaemia/calcaemia/natraemia/magnesia, hypernatremia,thiaminedeficiency, • Idiopathic Causes – epilepsy • Neoplastic Causes – brain tumours, metastases • Drugs – alcohol, drug withdrawal, drug intoxication, medication sideeffects, poisoningFocal Seizure Symptoms • Motor symptoms (e.g., localized jerking): Often associated with frontal lobe seizures. • Sensorysymptoms (e.g., pins and needles, auditory changes, abnormal tastes or smells): Suggest involvement of the parietal lobe. • Visual symptoms (e.g.,visual distortions, flashes, or seeing non-existent objects): Indicate activity in theoccipital lobe. • Automatisms (e.g., purposeless repetitive movements likechewing, swallowing, or hand gestures): Are typicallyseen in temporal lobeseizures and are morecommon in focal unaware seizures.Generalized Seizure Symptoms 1.Tonic-Clonic Seizures (formerly "Grand Mal"): Tonic phase: Muscles stiffen Clonic phase: Rapid, rhythmic jerkingof the limbs occurs, often accompanied byfacial twitching. 2. Tonic/ Clonic 3.AbsenceSeizures: Brief episodes of staringor "spacing out," often mistaken for daydreaming. Can have subtle movements (e.g.,blinking, lip smacking). Usually lasts 5–10 seconds. Normally the person is unaware. 4. Myoclonic Seizures: Sudden, brief jerking movements of muscles or groups of muscles. Typically lasts a fraction of a second to a few seconds. 5. Atonic Seizures (Drop Attacks): Sudden loss of muscletone, causing theperson to go limp and potentiallycollapse.Pathophysiology of Seizures If there is too much glutamate, neurones may become hyper-excitable makingseizures more likely. If there is not enough GABArelease, or too much GABA is degraded by GABA-T,there may not be enough inhibition on neurones, making them more excitable in seizures. The balance between these excitatoryand/orinhibitory signalling pathways are affected by the conditions in the VITAMIN D pneumonic making seizures and conditions like EPILEPSY more susceptible.Epilepsy ● Seizure lasting 5 minutesor longer, ● Two or more seizureswithout full recovery of consciousness between episodes It’s a medical emergency that can cause significant brain injury. Acutely, it is treated with anticonvulsants/antiepileptics.Treatment: Anti Seizure Medications 1. Block voltage-gated Na channels. Eg: carbamazepine, phenytoin, valproic acid and lamotrigine. 2. Block Ca channels.Eg: lamotrigine and topiramate blockHVA Ca channels whilst valproic acid blocks T-type Ca channels. 3. Block AMPA receptors – eg topiramate. 4. Stop vesicles containing glutamate fusing with the presynaptic membrane. Eg levetiracetam binds SV2A receptors in the vesicles to prevent them releasing glutamateTreatment: Anti Seizure Medications 5. Block NMDA receptor. Eg: felbamate which prevents calcium influx and further depolarisation 6. Prolong opening of GABA-A channel so more GABA can give inhibitory effects– benzodiazepines 7. Block GAT-1 eg tiagabine 8. Block GABA-T eg vigabatrinSide Effects dose adjustments. Forexample, lamotriginelevels may decrease,uiring necessitatingan increase in doseBSSJazakallah KHair for Listening :))