Flashcards in CN LANGE - Seizures & Syncope I Deck (107):
2 major causes of episodic loss of consciousness:
Disorders characterized by temporary neurologic signs or symptoms resulting from abnormal, paroxysmal, and hypersynchronous electrical neuronal activity in the cerebral cortex.
Loss of consciousness due to reduced blood flow to BOTH cerebral hemispheres OR the brainstem.
Events at onset of spell - Aura - Note that ...?
More than one type of aura may occur in an individual patient.
What aura is commonly associated with seizures originating in the temporal lobe?
A sensation of fear, olfactory or gustatory hallucinations, or visceral or deja vu sensations.
Events at onset of spell - Focal symptoms that suggest a seizure originating in the CONTRALATERAL frontoparietal cortex?
Focal MOTOR or SENSORY phenomena (eg involuntary jerking of one hand, hemifacial paresthesias, or forced head turning).
Events during the spell - Brief stiffening or jerking:
Cerebral hypoperfusion can also result in stiffening or jerking movements, especially if hypoperfusion is prolonged because the patient is prevented from falling or otherwise assuming a recumbent posture.
--> Sometimes referred to as CONVULSIVE SYNCOPE.
Events after the spell - Prolonged confusion:
1. Prolonged post-ictal state may follow status epilepticus.
2. May also occur after a single seizure in patients with diffuse structural cerebral disease (eg dementia, other cognitive impairment, or encephalitis), metabolic encephalopathy, or continuing non convulsive seizures.
Events after the spell - Fecal incontinence:
Prevalence of epilepsy in the general population:
Lifetime probability of a seizure:
2 historic features most suggestive of a seizure are the ...?
1. Aura associated with seizures of focal onset.
2. The postictal confusional state that follows generalized tonic-clonic seizures.
Seizures - Etiology - Genes implicated in susceptibility to epilepsy include those coding for:
4. Chloride channels.
5. Nicotinic, cholinergic, GABA, and G-protein coupled receptors.
Common causes of new-onset seizures - Primary neurologic disorders:
1. Benign febrile convulsions of childhood.
2. Idiopathic/cryptogenic seizures.
3. Cerebral dysgenesis.
4. Symptomatic epilepsy (trauma, stroke, mass lesions, infections).
Common causes of new-onset seizures - Systemic disorders:
2. Hyperosmolar states/Hyperthermia/Hypertensive encephalopathy.
4. Hepatic encephalopathy.
6. Drug toxicity.
7. Drug withdrawal.
8. Global cerebral ischemia.
Benign febrile convulsions occur in ...-...% of children aged 6mo-5yr.
2-5% --> Usually during the first day of a febrile illness (temperature > 38C) and in the ABSENCE of CNS infection (meningitis, encephalitis).
Benign febrile convulsions - Mutations in several genes have been linked to febrile convulsions including:
1. G-protein coupled receptor MASS1.
2. Inositol monophosphatase IMPA2.
3. SCN1A/SCN1B/SCN2A sodium channel subunits.
4. KCNQ2/KCNQ3/KCNA1 potassium channel subunits.
5. GABRG2/GABRD GABA receptor subunits.
Benign febrile convulsions usually last for less than ...?
10-15 minutes and LACK focal features.
Benign febrile convulsions - Seizures occurring when and in whom are associated with an increased risk for recurrence?
1. During the 1st hour of fever in children younger than 18months.
2. In children with a family history of febrile seizures.
--> 90% of recurrences occur within the next 2 years.
Benign febrile convulsions - The probability of developing a chronic seizure disorder is ...?
Idiopathic (cryptogenic) seizures - These account for ...?
2/3 of new-onset seizures in the general population.
--> Broad age range = 10-70.
Idiopathic seizures - Risk of recurrence in the next 5yrs:
Approx. 35% after a first unprovoked seizure.
--> A 2nd seizure increases the risk of recurrence in the 1st year.
Genes implicated in idiopathic generalized epilepsy:
1. Mitochondrial NAD-dependent malic enzyme ME2.
2. CACNA1A and CACNB4 calcium channel subunits.
Head trauma - Seizures that occur within the first ... after NON penetrating head injuries are NOT predictive of a chronic seizure disorder.
Stroke affecting the cortex produces seizures in ...-...% of patients.
5-15% --> Can occur after thrombotic or embolic infarction or intracerebral hemorrhage.
Seizures in patients with AIDS:
Most often related to HIV-dementia, but also occur with toxoplasmosis or cryptococcal meningitis.
Developmental anomalies that may cause seizures:
1. Cortical dysgenesis.
2. Neuronal migration disorders.
--> Predispose to epilepsy.
Hypoglycemia can produce seizures:
Especially with serum glucose levels of 20-30 --> Manifestations also relate to the RATE at which serum glucose levels fall.
Hyponatremia may be associated with seizures:
Less than 120 --> Higher levels after RAPID DECLINE.
Hyperosmolar states may cause seizures:
Hyperosmolar nonketotic hyperglycemia + Hypernatremia.
--> When serum osmolarity >330.
Hypocalcemia may cause seizures:
4.3-9.2mg/dL --> With or WITHOUT tetany.
Uremia may cause seizures:
Especially when it develops rapidly --> This tendency correlates POORLY with absolute serum urea nitrogen levels.
Porphyria may lead to seizures - Why difficult to treat?
Because most anticonvulsants can exacerbate the metabolic abnormalities.
--> Case reports attest to the safety and efficacy of gabapentin, pregabalin, and levetiracetam in porphyria.
Drug OD may lead to seizures - MC drugs:
Alcohol withdrawal seizures occur within ...?
48hr after cessation or reduction of ethanol intake in 90% of cases --> Characterized by brief flurries of 1 to 6 attacks that resolve within 12hr.
Important point to keep in mind about focal seizures:
Rarely due to alcohol or sedative drug withdrawal ALONE --> Suggest an additional focal cerebral lesion that requires evaluation.
Global cerebral ischemia may also be associated with:
1. Spontaneous myoclonus.
2. After consciousness returns - with myoclonus precipitated by movements (Action myoclonus).
Isolated seizures after global cerebral ischemia do or do not necessarily indicate a poor outcome?
Hyperthermia - Clinical features of severe hyperthermia include:
2. Confusional states or coma.
4. Renal failure.
Patients who survive hyperthemia may be left with ...?
ATAXIA as a result of the special vulnerability of cerebellar neurons to hyperthermia.
Major categories of drugs reported to cause seizures:
1. Antibiotics --> Quinolones, penicillins, INH.
6. Chemotherapeutics (etoposide, ifosfamide, cisplatin).
7. Cyclosporine, FK506 (tacrolimus).
8. Hypoglycemic agents.
9. Hypo-osmolar parenteral solutions.
11. Local anesthetics.
13. Narcotic analgesics.
15. SNS mimetics.
Non epileptic seizures - The DDx should include:
Frontal lobe seizures --> May be marked by unusual midline movements (pelvic thrusting or bicycling) and by very brief post-ictal states --> Ictal EEG abnormalities may escape detection as well.
Nonepileptic seizures - It is important to appreciate that ...?
Many patients with nonepileptic seizures also have genuine epileptic attacks that require anticonvulsant medications, but these should be prescribed at an empirically appropriate dose.
--> Psychiatric referral may be helpful.
Seizures - Classification:
1. Generalized --> Tonic-clonic, absence, other (tonic, clonic, myoclonic, atonic).
2. Partial (focal) --> Simple partial, complex partial, partial with secondary generalization.
Generalized tonic-clonic seizures:
Attacks in which consciousness is lost, without aura or other warning.
--> When a warning does occur, it usually consists of nonspecific symptoms.
Generalized tonic-clonic seizures - Tonic phase - The initial manifestations:
Unconsciousness and tonic contraction of limb muscles for 10 to 30 seconds --> Producing first FLEXION and then EXTENSION --> Particularly of the back and neck.
Generalized tonic-clonic seizures - Tonic contraction of the muscles of respiration may ...?
Produce an expiration-induced vocalization (cry or moan) and cyanosis - And contraction of masticatory muscles may cause tongue trauma.
Generalized tonic-clonic seizures - Clonic phase:
Ventilatory efforts return immediately after cessation of the tonic phase, and cyanosis clears.
--> Sphincter relaxation or detrusor muscle contraction may produce urinary incontinence.
Generalized tonic-clonic seizures - Recovery - As the patient regains consciousness:
There is postictal confusion and often headache.
Status epilepticus is defined arbitrarily by ...?
Seizure continuing for 5 to 30 minutes without ceasing spontaneously or that recur so frequently that full consciousness is NOT restored between successive episodes.
Why is status epilepticus a medical emergency?
Because it can lead to permanent brain damage from:
2. Circulatory collapse.
3. Excitotoxic neuronal damage if untreated.
Genetically transmitted seizures that ALWAYS begin in childhood and RARELY persist into adolescence.
Absence seizures - Genes:
1. Voltage-gated calcium channel.
2. GABAa receptor subunits.
3. Malic enzyme 2.
4. Inhibin alpha precursor.
Absence seizures - How many daily?
As many as SEVERAL HUNDREDS spells daily --> Impaired school performance and social interactions --> Children may be mistakenly thought to be mentally retarded.
Absence seizures - The spells are characteristically ...?
Inducible by HYPERVENTILATION.
Absence seizures - EEG pattern:
3Hz spike-wave activity.
Other types of generalized seizures - Tonic seizures:
Cause of drop attacks: The accompanying arrest of ventilatory movements leads to cyanosis.
Other types of generalized seizures - Myoclonic seizures:
Sudden, brief, shocklike contractions that may be localized to a few muscles or one or more extremities or may have a more generalized distribution causing falls.
MCC of myoclonic seizures:
Juvenile myoclonic epilepsy --> Onset usually in adolescence.
There is a family history of seizures in ... of patients with myoclonic seizures.
Myoclonic seizures - The disorders is genetically heterogenous, with linkage in different families to the ...?
1. Calcium channel beta4 subunit.
2. CASR calcium channel sensor receptor.
3. GABAa receptor alpha one and delta subunits.
Myoclonic seizures may also be associated with a variety of rare hereditary neurodegenerative disorders, including:
1. Unverricht-Lundborg disease (cystatin B mutations).
2. Lafora body disease (laforin mutations).
3. Neuronal ceroid lipofuscinosis.
4. Mitochondrial encephalomyopathy (myoclonus epilepsy with ragged red fibers on skeletal muscle biopsy).
Result from loss of postural tone, sometimes after a myoclonic jerk, leading to a fall or drop attack.
Atonic seizures are most common in developmental disorders such as:
Simple partial seizures --> Clonic movements of a single muscle in the face, a limb, or the pharynx may occur and may be self-limited --> They may be recurrent or continuous or may spread to involve contiguous regions of the motor cortex.
During simple partial seizures, consciousness is preserved unless and until the ...?
Seizure discharge spreads to other areas of the brain --> Producing tonic-clonic seizures --> Secondary generalization.
The aura is ...?
The portion of the seizures that precedes loss of consciousness and of which the patient retains some memory.
--> Sometimes it is the sole manifestation of the epileptic discharge.
In the postictal state, a focal neurologic deficit such as ...?
Hemiparesis (Todd paralysis) may persist for 30 minutes to 36hr and indicates an underlying focal brain lesion.
Complex partial seizures, formerly called ...?
Temporal lobe or psychomotor seizures and sometimes now referred to as focal seizures with DYSCOGNITIVE features.
--> Partial seizures in which consciousness, responsiveness, or memory is impaired.
The MOTOR manifestations of complex partial seizures are characterized by:
Coordinated involuntary motor activity, termed AUTOMATISM, which takes the form or orobuccolingual movements in approx. 75% of patients and other facial or neck or hand movements in approx. 50%.
Diagnosis - Specific EEG features that suggest epilepsy:
1. Abnormal spikes.
2. Polyspike discharges.
3. Spike-wave complexes.
Evaluation of a new seizure disorder in a STABLE patient:
1. History (incl. medications + drug exposure).
2. General physical + complete neurologic exam.
3. Blood studies (fasting glucose, serum electrolytes, calcium, renal function studies, hepatic function studies, CBC, serum FTA-ABS).
4. EEG (abnormal in 20-60% of first EEGs; 60-90% with repeated EEGs).
5. Brain MRI --> Especially with abnormal neurologic exam, progressive disorder, or onset of seizures after age 25yr.
After a single generalized tonic-clonic seizure, recurrence of one or more seizures can be expected within ...?
3-4years in 30% to 70% of untreated adult patients.
The 4 key principles in seizure management:
1. Establish the diagnosis of epilepsy before starting drug therapy.
2. Choose the right drug for the seizure type.
3. Treat the seizures rather than the serum drug levels.
4. Evaluate one drug at a time.
Treatment strategies - Partial or secondarily generalized tonic-clonic seizures:
5. Sodium valproate.
Aside from ..., all currently-available seizure medications have demonstrated efficacy in treating partial seizures.
Ethosuximide (perhaps rufinamide).
Why is gabapentin not initially used for seizure treatment?
As its short half-life is a significant limitation.
Generalized seizures - Treatment:
1. Valproic acid is effective for all types of primary generalized seizures - Not recommended as the initial treatment in women of childbearing age.
2. Levetiracetam, topiramate, lamotrigine, and zonisamide can be used successfully in generalized epilepsies.
Absence seizures - Treatment:
1. Sodium valproate.
--> Valproate also provides protection against tonic-clonic seizures, BUT ...has caused fatalities from hepatic damage in children younger than 10 (usually
Other options for absence seizures:
--> As with valproate, they provide protection against tonic-clonic seizures, as well.
Myoclonic seizures - Treatment:
Treatment of seizures - Changing to a different drug:
1. A different anticonvulsant should be introduced only if seizures continue to occur after maximum therapeutic benefit has been achieved with the initial drug.
2. An anticonvulsant that has failed to alter seizure frequency should be discontinued GRADUALLY ONCE therapeutic levels of the new drug have been achieved.
3. Transition to monotherapy with a different drug is recommended before trials of 2-drug combination therapy.
What should be considered when no treatable cause can be found, seizures are NOT due to a progressive neurodegenerative disease, and medical treatment has been unsuccessful for at least 2 years?
Evaluation for possible SURGICAL therapy should be considered.
Most frequent candidates for surgical therapy?
Patients with complex partial seizures arising from a single temporal lobe.
--> Unilateral anterior temporal lobectomy abolishes seizures and auras in approximately 50% of these patients and significantly reduces their frequency in another 25%.
Emergency evaluation of serial seizures or status epilepticus?
1. Treatment with anticonvulsants should be instituted immediately, while the following measures are taken.
2. Vital signs: BP to exclude hypertensive encephalopathy and shock, temp to exclude hyperthermia, pulse to exclude arrhythmia.
3. Draw venous blood for serum glucose, calcium, electrolytes, hepatic and renal function studies, CBC, ESR, and toxicology.
4. Insert IV line.
5. Administer glucose (50mL of 50% dextrose) IV.
6. Obtain any available history.
7. Rapid physical exam (trauma, meningeal irritation, systemic infection).
9. Focal neurologic signs.
10. Evidence of metastatic, hepatic, or renal disease.
11. Arterial blood gases.
12. LP (if not contra).
14. Calculate serum osmolarity.
15. Urine sample for toxicology.
The systemic physiologic consequences of status epilepticus are related to ...?
1. Incr. motor activity.
2. High levels of circulating catecholamines.
3. Hyperthermia (42-43C) in the absence of infection.
4. Lactic acidosis.
5. Peripheral blood leukocytosis.
Which systemic physiologic consequence of status epilepticus requires specific attention?
Only hyperthermia --> It is known to increase the risk of brain damage.
--> Cooling blanket, and, if necessary, the induction of motor paralysis with a neuromuscular blocking agent.