520976
Description
Flashcards by Mark George, updated more than 1 year ago
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Created by Mark George
almost 11 years ago
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| Question | Answer |
| Causes of Seizures that are not epilepsy | Drug withdrawal. Drug overdose. Medication side effect. Syncope . Metabolic causes. Stroke. |
| Pathophysiology of Seizures that are not epilepsy. | Abnormal neuronal firing caused by changes in membrane permeability to ions. |
| Epilepsy Risk Factors | Developmental - CNS structural abnormalities • Perinatal problems, hypoxia, trauma, febrile seizures • Head trauma • CNS infection • Brain tumours • Stroke • Alcohol/ drug abuse • Familial history |
| Pathophysiological mechanisms of Epilepsy. | (1) Impaired voltage dependant Na+, K + & Ca++ ion channels result in membrane hyperexcitability (2) alterations to inhibitory neurotransmitter ligand gated GABA receptors, and to a lesser extent nicotinic and acetylcholine channels (3) Receptors have been found to be mutated in some familial forms, resulting in abnormal patterns of electrical activity |
| Epilepsy pathophysiology | Depolarisation results in an ionic imbalance, with an intracellular accumulation of Na+ and a depletion of K+. The net result is sustained membrane depolarisation & seizure activity • Epileptogenic focus- generates large numbers of autonomous paroxysmal discharges. These may be localised (focal) or involve the entire brain simultaneously (generalised) • Over time a focal lesion can induce an epileptic focus in the opposite cerebral hemisphere through connecting pathways |
| Epilepsy precipitating factors | Fatigue Sleep deprivation Emotional stress Febrile illness Menstrual cycle Odours Flashing lights Music |
| Where do partial seizures often originate? | Temporal lobe |
| How is consciousness affected in Simple partial seizures? | Consciousness not impaired |
| How is consciousness affected in complex partial seizures? | Consciousness becomes impaired |
| Simple partial seizures may include which type symptoms? | Somato-sensory, autonomic or psychic symptoms. |
| Examples of generalised seizures | Tonic-Clonic (most common) Absence seizures Myoclonic seizures Atonic (drop attacks) |
| Tonic-Clonic seizures - stages of. | Prodromal phase. Ictal phase. Tonic phase. Clonic phase. Post-ictal phase. |
| Tonic-Clonic seizures • Prodromal phase | A period of irritability and tension. Some may experience an aura. |
| Tonic-Clonic seizures Ictal phase | Starts with sudden loss of consciousness, fall to the ground |
| Tonic-Clonic seizures Tonic phase | Body becomes rigid, may utter a cry, bladder and bowel (less common) may empty, respiration is disrupted, may become a dusky colour, pupils dilate and become unresponsive to light. |
| Tonic-Clonic seizures Clonic phase | Inhibitory neurones of the cerebral cortex, ant. thalamus & basal ganglia become active. |
| Tonic-Clonic seizures Clonic phase characteristics. | Violent rhythmic muscular contractions, hyperventilation, facial contortion, excessive salivation, sweating & tachycardia. Clonic jerking subsides and the extremities become limp, breathing is quiet & pupillary reflex returns. |
| Tonic-Clonic seizures Post-ictal phase. | State that follows the seizure |
| Tonic-Clonic seizures Post-ictal phase. Characteristics. | On awakening most are confused, disorientated and amnesic • Headache, muscle fatigue are common, may have bitten tongue, sustained a # or joint dislocation. May sleep for several hours • Rarely may have a temporary neurological deficit – Todd’s paralysis |
| Seizures diagnostic tools. | Baseline blood chemistry. Electroencephalogram (EEG) / sleep deprived EEG. CT scan. MRI. Video EEG monitoring. |
| Status Epilepticus (SE) - definition. | Either continuous seizures lasting at least 5 minutes, or 2 or more discrete seizures between which there is incomplete recovery of consciousness. |
| At a cellular level prolonged SE leads to? | Decreased brain PaO2. A Mismatch in O2 and glucose requirements with cerebral blood flow leading to an acute depletion of O2 and glucose. |
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