Epilepsy Flashcards
Briefly define the following terms: a. epilepsy b. seizure c. convulsion.
a) “Epilepsy”a chronic recurrent paroxysmal disorder of cerebral function characterised by sudden brief attacks of altered:
o consciousness
o motor activity
o sensory phenomena
o inappropriate behaviour
o caused by excessive discharge of cerebral neurons.
b) “Seizure”: The sudden attack or recurrence of a disease e.g. epileptic seizure
c) “Convulsion”: A violent involuntary contraction of voluntary muscles
Briefly discuss the aetiology of: a. primary epilepsy
a) Primary (Idiopathic) i.e. aetiology is unknown
o in most cases, an inherited disposition is believed to be the cause the precise nature of the genetic anomaly is unknown
o represents 75% of cases of epilepsy in young adults
o often 2o epilepsy is undiagnosed as such and hence is classified erroneously as 1o
o usually begins between 2-14 years
Briefly discuss the aetiology of b. secondary epilepsy
b) Secondary (symptomatic)
o i.e. epilepsy secondary to structural or metabolic disease of the CNS resulting in disordered function and epilepsy.
o Conditions which may cause secondary epilepsy include:
o hyperpyrexia
o CNS infections (meningitis, AIDS etc.)
o metabolic disturbance e.g. hypoglycaemia, hypoparathyroidism
o convulsive agents and toxic agents e.g. lead, alcohol, cocaine
o cerebral hypoxia (anaesthesia, Co poisoning etc.)
o expanding brain lesions
o brain defects (congenital etc.)
o cerebral oedema (eclampsia)
o anaphylaxis
o cerebral infarct/haemorrhage
o withdrawal from alcohol, medication, drugs etc.
o The seizures in secondary epilepsy usually do not recur once the illness ends.
If the condition has resulted in a permanent CNS, lesion/scar the recurrence of the epilepsy may occur.
Briefly discuss the classification of epilepsy. b. Indicate the frequency of each of the major types of epilepsy
a) Classification is according to clinical picture. The reason for this is because treatment is based on clinical type. International classification of epileptic seizures:
Partial (focal, local) seizures
o Simple partial seizures (consciousness not impaired)
o With motor signs (includes Jacksonian seizures)
o With somatosensory or special-sensory symptoms (hallucinosis)
o With autonomic symptoms or signs
o With psychic symptoms (includes dysphasic, dysmnesic, cognitive and affective symptoms)
Complex partial seizures.
o Any simple partial seizures onset followed by impairment consciousness
o Impairment of consciousness only
Generalised seizures Absence seizures o With impairment of consciousness only o With clonic components o With atonic components o With tonic components o With automatisms o With autonomic components
Myoclonic seizures o Clonic seizures o Tonic seizures o Tonic-clonic seizures Atonic seizures due to incomplete data
Discuss the pathology of epilepsy
a) Primary Generalised Epilepsy ( Grand Mal and Petit Mal)
o no discernible anatomical changes seen with autopsy but: CT & MRI often show foci of:
o atrophy
o calcification
o malformations (eg developmental)
b) Secondary epilepsies
o many have definable lesions in the CNS e.g.
o zones of neuronal loss and gliosis (scars)
o hamartomas
o vascular malformations
o tumours
o NB. PET (positron emission tomography) is good for locating regions of hypoperfusion of hypometabolism.
o It should be noted that scars etc. have been found in non-epileptogenic areas of the brain as well i.e. not all lesions are epileptogenic.
6) Briefly discuss the pathophysiological theories pertaining to epilepsy.
Poorly understood.
Abnormalities implicated.
a) intrinsic neuronal membrane changes that result in abnormal ionic conductance
b) abnormal neurotransmitter synthesis resulting in:
o deficient inhibitory neurotransmitters
o excessive excitatory neurotransmitters
o deficient, genetically regulated, intracellular enzymes that affect the neuron’s ability to pump ions and repolarise.
o glial cell abnormalities
RESULT:
(i) hyperexcitability (possibly clinically hyperexcitable)
(ii) chronic partial depolarization
(iii) irregular firing at rates of 70-100/sec.
(iv) cell membranes with increased ionic permeability
7) List four (4) factors which may induce a seizure in an epileptic.
o hyperthermia o hypoxia o hypoglycaemia o hypocalcaemia o hyponatraemia o related sensory (e.g. photic) stimulation
8) List and describe the parts of the “typical” or generic epileptic seizure.
Observe either
a) a diffuse tendency to hyperexcitability of CNS neurons or
b) The presence of a deep, cryptic epileptogenic abnormality which involves centrally located subcortical activating mechanisms.
c) Unknown factors/circumstances result in a diffuse, synchronous, abnormal discharge of CNS neurons: i.e. a generalised epileptic seizure occurs
Write notes on Partial seizures.
2 kinds: Focal or Complex
Focal:
The seizure usually begins somewhere in the sensorimotor cortex. Thus the seizures begin focally with a specific
o motor
o sensory
o psychic
o autonomic
o Aberrations or dysfunction which reflects the affected part of the cerebral hemisphere in which the seizure originated.
o There is no loss of consciousness or self-awareness. i.e. a simple partial seizure is equivalent to the “aura”.
o A variant called the Jacksonian seizure exists which is characterised by:
o focal motor symptoms and signs beginning in one hand or foot, and then march up the extremity
o dysfunction which may remain localised or may become generalized
COMPLEX PARTIAL
Synonyms: = Temporal lobe = psychomotor seizures
Usually originate in one of the temporal lobes.
The seizure results in an impairment or loss of consciousness.
Observe two variants:
1.
o an initial partial seizure with symptoms and signs reflecting its origin in the temporal lobe
o a change in the initial symptoms and signs in which we observe motor components (automatisms) eg lip smacking, chewing movements, fumbling of hands, complex behaviour e.g. driving a car.
o The patient gradually experiences varying degrees of impaired consciousness and memory (may have postictal amnesia).
2. observe impairment of consciousness only.
o Patients with complex partial (temporal lobe epilepsy experience an increased incidence of interictal psychiatric disorders.
o 33% have substantial psychological difficulties
o 10% have symptoms and signs of schizophreniform or depressive psychosis
11) Write notes on Absence seizures (Petit mal).
o Begin in childhood (2-12 years, Usually cease by 20 years. o 2 kinds: o Simple absence attacks o last a few seconds o loss of consciousness o blank stare o blinking of eyelids (3-4 Hz) o child is unaware of event o 100’s of attacks may occur in 1 day o complex absence attacks o last 15-30 seconds o loss of muscle tone o mild rhythmic movements (muscle fluttering) o brief motor automatisms o The patient is normal between attacks o Usually occur when the patient is sitting quietly
12) Write notes on events occurring during Tonic-clonic seizures (Grand mal). In your answer you should list and briefly describe the characteristics of each of the stages of this seizure
o Usually loss of consciousness occurs at the outset.
o Some patients experience a partial “aura” in which epigastric discomfort occurs.
o Some patients have prodromal warnings (not auras) which may precede the attack by several hours. Observe:
o mood changes
o apprehension
o insomnia
o anorexia
o episodes of repeated myoclonus
o As the attack begins, many patients cry out unconsciously.
o The attack then proceeds as follows:
o consciousness is lost and the patient falls
o tonic contraction of muscles occurs i.e. muscles stiffen in extension and breathing is usually arrested and causes deep cyanosis
o the tonic phase lasts less than one minute
o clonic contraction of muscles then occurs i.e.
o gradually the tonic extension gives way to a rapid succession of clonic contractions of the neck, trunk and extremities
o the clonic phase lasts 1 minute
o flaccid relaxation then occurs
o during the flaccid relaxation stage we observe stertorous breathing, pallor and heavy salivation
o arousal phase occurs 2-3 minutes after the relaxation phase
o postictal manifestations:
o HA
o muscle fatigue
o muscle weakness
o drowsiness
o confusion
o most patients sleep for several hours postictally
o NB: Urinary and faecal incontinence may occur in grand mal seizures
13) How is epilepsy diagnosed?
o Clinical picture o Electroencephalography o History (previous history, familial etc.) o Must exclude 2o epilepsy with: o CT/MRI o serum glucose o serum Ca2+
List the main therapeutic modalities which are used to treat epilepsy.
o Drug Therapy
o Treat any conditions that exacerbate epilepsy
o Surgery
List four (4) side effects of anticonvulsant drug therapy
a) Drowsiness, N&V, confusion
b) Osteopenia
c) Aplastic anaemia
d) Megaloblastic Anaemia
16) Discuss the prognosis of epilepsy which is treated using anticonvulsants.
Drug therapy achieves the following:
Grand Mal:
o 50% cases are completely controlled
o 35% cases frequency of attacks is greatly reduced
Petit Mal: o 40% of cases are completely controlled o 35% of cases have decreased frequency o Psychomotor o 35% of cases are controlled o 50% of cases have decreased attacks o In patients with well controlled seizures about 50% eventually discontinue drugs without seizure relapse. o However in patients who do relapse the relapses are often worse than the original epilepsy i.e. more severe attacks occur.
