Seizures & Epilepsy

Pregunta	Respuesta
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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	Creado por Mark George hace casi 11 años