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114 Cards in this Set
- Front
- Back
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Describe the four types of sensory receptors
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Meissner - tonic, attached to hairless skin, Pacinian - tonic, subcutaneous, Ruffini - phasic, all skin, Merkel - phasic, all skin and hairs
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What do astrocytes, oligodendrocytes and microglia do?
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Astrocytes - provide nourishment, clean out synapses and plug leaks in blood vessels, Oligodendrocytes - make myelin and prevent neural regeneration, Microglia - function as an immune system within the central nervous system.
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What fibers are carried in the Dorsal Ventral and intermediate horns of the spinal cord?
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Dorsal horn - Sensory fibers. Intermediate horn - autonomic sensory and motor fibers, Ventral horn - motor fibers
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Describe the pathway for pain and temperature fibers
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Receptors → DRG → dorsal horn where they synapse. Postsynaptic fibers then decussate a few segments above the level of entry and then ascend the cord contralaterally in the spinothalamic tract. Fibers are sent to the medial dorsal intralaminar nucleus, brainstem reticular formation and the ventral posterior nucleus.
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What type of fibers pas through the neospinothalamic and the paleospinothalamic subtracts?
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Neospinothalamic tract carries fast (A delta) mapped fibers, Paleospinothalamic tract carries slow (C)fibers for dull pain.
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Describe the pathway for tactile touch
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Receptors → DRG → dorsal horn where they immediately ascend the cord in the dorsal column tract. Fibers decussate in the sensory deccusation in the brainstem and travel to the cunate and gracile nuclei.
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Which is more medial/lateral the gracile or cunate tract? Which relays information from the upper/lower limb?
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Upper - lateral - gracile, lower -medial - cunate
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Describe how skilled motor fibers leave the brain and travel through the cord
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Skilled motor function starts in the parietal motor and frontal cingulate cortices. These fibers collect into the corona radiata → internal capsule → cerebral peduncles and through the pyramids where the fibers decussate. These fibers then travel down the corticospinal tract.
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What is spinal shock?
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Following an injury to the cord all reflexes below that level are inactive for several weeks- months
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What is autonomic dysrefelxia?
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A syndrome that occurs following injury to the spinal cord (weeks -years). AD only occurs with those with spinal cord injuries above the heart T5-6. Mechanism - a painful stimulus below the level of injury activates sympathetics → ↑BP below. Ascending tracts are severed so the brain cannot control the response. Eventually baroreceptors are triggered and relay the information to the brain but the descending parasympathetics cannot switch off the response.
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What spinal levels control the following reflexes, biceps, brachioradialis, triceps, patellar, Achilles?
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Biceps C5, Brachioradialis C6 triceps C7 Patella L4, Achilles S1
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What segments of the spinal cord contain sympathetic/parasympathetic cells?
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The sympathetic trunk extends from T1-L2. Parasympathetic function is from L2-L4 as well as in the cervical section serving the cranial nerves III, VII, IX and X
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What are fast and slow fibers called?
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Fast are A delta fibers, Slow are unmyelinated C fibers
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What is the prevalence of Neuropathic pain in amputees?
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40-60%
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What is the prevalence of neuropathic pain in MS sufferers?
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22%
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What is the greatest cause of head injury
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MVA 50% followed by sporting 20%
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By how much is life expectancy reduced for a quadriplegic? Paraplegic?
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Quadriplegic 70% Paraplegic 84%
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What is the level of sympathetic supply to the heart?
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T6
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How many segments does the human spinal cord have?
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31
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Describe the signs of a lower motor neuron lesion
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Absent reflexes, muscle wasting, paralysis, decreased tone
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Describe the signs of an upper motor neuron lesion
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Heightened reflexes, increased tone, paralysis or paresis, increased tone
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What effect do sympathetic signals have on the bladder?
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Relaxation of the detrusor leading to reflex continence
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What effect do parasympathetic signals have on the bladder?
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Contraction of the detrusor leading to a mictuition reflex
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Where is CSF produced? Where is it absorbed?
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Produced in the choroid plexus in the floor of the lateral horn and in the temporal horn as well as in the empendyma of the ventricular system. It is absorbed in arachnoid villi.
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What is hydrocephalus? What are its symptoms?
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An increase in VOLUME of CSF that results in headache, papilloedema, diplopia and focal neurological symptoms.
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What is Pseudotumor Cerebri?
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An idiopathic increase in ICP found in young overweight females without any sign of a space occupying lesion.
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What is the treatment for raised ICP?
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Treatment for hydrocephalus is acetozolamide or installation of a ventricular shunt
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Describe how GABA-A receptors work
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GABA-A receptors are ionotropic (fast) receptors. When GABA binds they open an ion channel allowing Cl⁻ influx therefore hyperpolarizing the cell inhibiting action potentials.
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Describe how GABA-B receptors work
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GABA-B receptors are metabotropic (slow) receptors. When GABA-B binds they inhibit cAMP which activate K⁺ channels that then hyperpolarize the cell inhibiting action potentials.
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Pheynytoin
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Anticonvulsant. Limits the firing frequency of neurons by stabilizing the inactive state of voltage gated Na⁺ channels. Also used to treat neuralgia and some cardiac arrhythmias.
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Barbiturates
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Anticonvulsant. Bind to GABA-A receptors potentiating GABA action, also block AMPA glutamate receptors. Therefore it acts as a CNS depressant. They increase the opening time of GABA activated Cl⁻ channels.
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Benzodiazepines
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Anticonvulsant. Modulate GABA-A receptors increasing their rate of firing leading to CNS depression.
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Carbamazepine
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Anticonvulsant. Stabilizes the inactive state of voltage gated Na⁺ channels. Useful in temporal lobe epilepsy
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Na⁺ Valporate
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Anticonvulsant. Inhibits the metabolism of GABA.
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Gamma vinyl GABA
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Anticonvulsant. Inhibits the catabolism of GABA therefore resulting in more GABA in the synaptic cleft, it is an analogue of GABA but is not a receptor agonist therefore it acts as a suicide substrate.
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Tiagabine
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Anticonvulsant. Blocks GABA uptake into presynaptic neurons thereby permitting more GABA to be available for receptor binding on the surface of post synaptic cells.
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What is the prevalence of epilepsy?
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1%
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What proportion of people will have a seizure in their lifetime?
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5%
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What percentage of epileptics have an identifiable neurological disorder?
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Only 25-30%
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Describe the difference between generalized and partial seizures
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Generalized:- First clinical indication involves both hemispheres , tonic-clonic, petit mal or myoclonic Partial:- Limited to part of one cerebral hemisphere and can be with or without loss of consciousness. Can involve automatisms
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At what day does neurulation occur
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20th day
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By what amount does folic acid reduce the incidence of spina bifida?
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70%
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Where is serotonin released? What does it do?
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Released in the raphe nuclei, controls behavior, mood, aggression, pain and blood flow
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Where is dopamine released? What does it do?
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Released in the Substancia Nigra and the Ventral Trigeminal Area, Controls behaviors regulation, focus, pleasure and motivation. Mostly active in the forebrain
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Where is Acetylcholine released? What does it do?
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Released in the BRF AcH groups Controls arousal, memory, ANS control, pain, dreaming
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Where is Noradrenaline produced? What does it do?
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Released in the Locus Coerruleus Controls ANS, pleasure and motivation, blood flow, global attention and neural plasticity.
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What nucleus supplies autonomic fibers to cranial nerve III?
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Edinger Westphal nucleus controls parasympathetic pupil contraction via the occularmotor nerve.
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What nucleus supplies parasympathetic fibers to cranial nerve VII
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Superior salivary nucleus supplies parasympathetic fibers to the submandibular and sublingual glands via the facial nerve VII
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What nucleus supplies parasympathetic fibers to cranial nerve IX
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Inferior salivary nucleus supplies parasympathetics to the parotid gland via the glossopharyngeal nerve IX
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What brainstem nucleus receives taste information? From which cranial nerves?
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The rostral solitary tract nucleus receives taste information from the Facial VII, Glossopharyngeal IX and Vagus X cranial nerves.
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What nucleus gives rise to efferent motor fibers to the vagus glossopharyngeal and accessory nerves to the pharynx and larynx?
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Nucleus ambiguus
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What are the signs of an upper motor neuron lesion of the corticobulbar tract?
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Facial paralysis with frontalis and orbicularis occuli spared on the contralateral side.
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What is the Herring Brauer Reflex?
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Pulmonary stretch receptors stop over inflation of the lungs via the vagus nerve.
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What are the benefits of a stroke unit?
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Decreased mortality by 17%, decreased death or dependency by 30%, 8% reduction in hospital stays.
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What percentage of strokes are hemorrhagic?
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20%
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Name the four types of syncope
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Vasovagal, orthostatic, psychotic, primary cardiac.
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What is the most common sites of atheroma that cause strokes?
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At the branching point of the internal carotid artery form the common carotid artery.
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Acutely following a stroke what is beneficial, aspirin? Anticoagulation?
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Aspirin is beneficial, anticoagulation has no effect.
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What is the difference between complex and simple seizures?
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Complex involves a loss of consciousness whilst simple does not
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List some triggers for seizures
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Sleep deprivation, alcohol (particularly withdrawal) physical and mental exhaustion, flickering lights (primary generalized), low blood glucose, intercurrent infections, metabolic disturbance.
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Describe a Grand Mal seizure
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Preceded by aura, patient goes rigid and unconscious, respiration is arrested, clonic jerks, post ictal confusion > 30min with loss of memory.
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How is spina bifida tested for antenatally?
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Neural tube defects can be detected by increased levels of serum alpha-fetoprotein. If abnormal further testing is required to make the diagnosis.
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What fibers pass through the pyramids?
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Corticospinal tract fibers from the contralateral cortex.
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What fibers pass through the superior cerebellar peduncle?
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These fibers pass from the cerebellum to the midbrain. This inferior cerebellar peduncle carries fibers to the cerebellum from the body.
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What do the superior colliculi do?
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Plays a role in hearing
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What do the inferior colliculi do?
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Plays a role in vision
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What proportion of strokes occur in the brainstem?
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25%
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Describe the symptoms of a stroke to the basilar artery in the medulla.
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Locked in syndrome with ocular palsy. All afferent and efferent fibers are lost leaving no communication between the brain and the body.
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Describe the symptoms of a stroke to the basilar artery in the pons
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Locked in syndrome without ocular palsy. Oculomotor nuclei are spared.
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Describe the symptoms of a stroke to the superior cerebellar artery.
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Ipsilateral ataxia, nausea, vomiting and los of pain and temperature sensation to the contralateral sde of the body due to the loss of the spinothalamic tract
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Describe the symptoms of a stroke to the AICA.
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Sudden onset vertigo, falls, marked horizontal nystagmus, absent sensation of one side of the face accompanied with facial paralysis.
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Describe the symptoms of a stroke to the PICA.
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Wallenbergs Syndrome: dysphagia, dysarthria (IX and X nuclei), vertigo, nausea, vomiting (vestibular nucleus), ipsilateral ataxia (inferior cerebellar peduncle). Ipsilateral Horner's syndrome (descending sympathetic fibers), loss of pain and temp in the ipsilateral face (V nucleus) and contralateral limbs (StT). There is no limb weakness.
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Describe what happens during cerebral ischemia at a cellular level.
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During ischemia there is a reduction in available ATP therefore ATP dependent Na⁺ K⁺ pumps stop working which leads to an increase in Na⁺ inside the cells which leads to an increase in Ca⁺ . This causes an excess of glutamate to enter the cell producing excitotoxicity. Also the increase in Ca⁺ causes direct damage to mitochondria leading to cell death via apoptosis.
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When is it ok to give TPA?
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Within the first 3 hours following a stroke once intracerebral haemorrhage has been ruled out.
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At what time of day is body temperature lowest?
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3-6am
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What signs are found on LP during bacterial and viral meningitis
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In bacterial: protein and neutrophils are high whilst glucose is low. In viral: glucose is normal or high and lymphocytes are high.
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What age group does haemophillus influenzae usually infect?
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Infants > 5 years old. This is decreasing due to vaccinations.
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What organism is associated with meningitis in the Immunosuppressed?
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Listeria
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What organisms causes meningitis following UTI?
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Staph Aureus
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What organisms is the commonest cause of meningitis in children?
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Meningococcal Meningititis
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What is the empirical therapy of meningitis?
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7 to 10 days of a 3rd generation cephalosporin with corticosteroids to prevent inflammation following bacterial cell lysis. Steroids must be given several minutes prior to treatment with antibiotics.
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What part of the brain is most commonly infected with herpes simplex virus?
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Temporal Lobes
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What percentage of right and left handed people have language lateralized to the left side of their brains?
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98% of right, 76% of left
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Describe a low grade astrocytoma
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Presents with seizures, median survival is 7 years. Treatment is via surgical resection and radiation
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Describe Glioblastoma Multiforme
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Most common malignant astrocytoma in 50-70year olds. MRI shows an irregular ring like contrast enhancement. Almost never metastasizes outside the head, median survival is one year.
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Describe Oligodenroglioma
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"Fried egg" cells, median survival is 16 years, most will spread to become malignant.
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What are the symptoms of raised ICP?
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Lowered consciousness, papilloedema, nausea, vomiting, cranial nerve signs (IV and VI), headache that is worse in the morning or with coughing.
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What is the incidence of brain tumours?
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15/100,000 per year
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What is the proposed mechanism of migraine?
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Neuronal hyper excitability in the inter ictal phase, cortical spreading depression (aura), trigeminal nerve activation (headache), progressive damage to the periaquaductal grey matter.
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Describe the symptoms of migraine
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Preceded by an aura, throbbing headache, photophobia, phonophobia, nausea.
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List some triggers for migraine
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chocolate, cheese, fatty foods, oranges, tomatoes, onions, menstruation, some medications
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Describe a cluster headache
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Excruciating unilateral headaches of extreme intensity ranging from 15min to a few hors. Onset is rapid and pain is associated with the eye and temporal area.
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What changes are seen in absorption in the elderly?
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Decreased motility, increase in passive transport, decrease in active transport
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What is the mechanism and treatment for hypotension following spinal cord injury?
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The mechanism involves the interruptionof supraspinal inputs to preganglionic sympathetic neurons. It is not the same as hypotension in shock and should not be treated with fluids.
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What type of paralysis is produced when the cauda equina is damaged?
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flaccid paralysis not spactic.
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Where on the retina is the nasotemporal division?
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At the fovea not the optic disk
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Which retinal cells relay information regarding movement?
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Magnocellular
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Which retinal cells relay information regarding colour?
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Parvocellular
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After crossing in the optic chiasm where do optic tract fibers go?
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Lateral genticulate nucleus
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Where does the primary visual cortex reside?
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On the banks of the calcatrine sulcus
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What does the suprachiasmatic nucleus do?
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Acts as a time keeper, sends fibers to the pineal gland
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What does the pretectrum do
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Controls the pupillary reflex and the EW nucleus
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Function of the Superior Colliculi
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Avoidance, attention, saccades
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What structure provides most of the eyes focusing power
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The cornea
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Describe the physiology of rods.
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Within rods: light causes a conformational change in a protein which causes the activation of G protein → ↓cGMP → closure of Na⁺ and Ca⁺ channels → hyper polarization → less glutamate release --> signal.
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What does 6/12 visions mean?
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The patient can see from 6 meters what an average person can see from 12 meters.
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What are secondary and primary demyelination?
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Primary refers to damage to the oligodendrocytes. Secondary refers to damage to myelin itself.
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How many times more common in women is MS?
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Twice
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What are the signs of MS on lumbar puncture
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Oligoclonal bands of IgG antibodies
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What does nataluzimab do?
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It is a selective inhibitor of adhesion factors, alpha-4-ntergrin antibody
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What is the initial presentation for the majority of MS sufferers?
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Motor dysfunction
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What nerve supplies the cornea?
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Ophthalmic branch of the trigeminal
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What is the name given to the border of the border of the cornea and the sclera
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The limbus
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