Pharmacotherapy of Epilepsy – PST06106 Basic Pharmacotherapy
NTA Level 6 • Semester 1 • PST06106 Pharmacotherapy of Epilepsy Basic Pharmacotherapy • Source Session/Topic 27 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. PST 06106 Basic Pharmacotherapy Session 27: Pharmacotherapy of Epilepsy Learning Tasks By the end of this session students are expected to be able to: Define epilepsy Explain pathophysiology of epilepsy Explain the clinical presentation of epilepsy Outline diagnosis of epilepsy Describe pharmacological treatment of epilepsy Describe the monitoring of epilepsy therapy Activity: Buzzing What is Epilepsy ? Definition of Epilepsy The term 'epilepsy' is used to define a group of neurological disorders all of which exhibit periodic seizures. Seizures are associated with episodic high-frequency discharge of impulses by a group of neurons (sometimes referred to as the focus ) in the brain. Epilepsy implies a periodic recurrence of seizures with or without convulsions. A seizure results from an excessive discharge of cortical neurons and is characterized by changes in electrical activity as measured by the electroencephalogram (EEG). Definition of Epilepsy Cont.…. A convulsion implies violent, involuntary contraction(s) of the voluntary muscles The site of the primary discharge and the extent of its spread determine the symptoms that are produced, which range from a brief lapse of attention to a full convulsive fit lasting for several minutes, as well as odd sensations or behaviours Table 27.1 Classification of Epilepsy Pathophysiology of Epilepsy Seizures result from excessive excitation, or in the case of absence seizures, from disordered inhibition of a large population of cortical neurons. Initially, a small number of neurons fire abnormally. Normal membrane conductance and inhibitory synaptic currents break down, and excess excitability spreads, either locally to produce a focal seizure or more widely to produce a generalized seizure. This onset propagates by physiologic pathways to involve adjacent or remote areas. The clinical manifestations depend on the site of the focus, the degree of irritability of the surrounding area of the brain, and the intensity of the impulse. Pathophysiology of Epilepsy Cont… There are multiple mechanisms that might contribute to synchronous hyper excitability, including: A lterations in the distribution, number, type, and biophysical properties of ion channels in the neuronal membranes; B iochemical modifications of receptors; M odulation of second messaging systems and gene expression; C hanges in extracellular ion concentrations; A lterations in neurotransmitter uptake and metabolism in glial cells Pathophysiology of Epilepsy Cont… Modifications in the ratio and function of inhibitory circuits. Local neurotransmitter imbalances between the main neurotransmitters, glutamate (excitatory) and γ -aminobutyric-acid (GABA) (inhibitory), and neuromodulators (e.g., acetylcholine, norepinephrine, and serotonin) might play a role in precipitating seizures in susceptible patients. Clinical Presentation and Diagnosis of Epilepsy General In most cases, the healthcare provider will not be in a position to witness a seizure. Many patients (particularly those with complex partial (CP) or generalized tonic clonic (GTC) seizures are amnestic to the actual seizure event. Obtaining an adequate history and description of the actual event (including time course) from a witness is critically important. Clinical Presentation and Diagnosis of Epilepsy Cont…. Symptoms Symptoms of a specific seizure will depend on seizure type. Although seizures can vary between patients, they tend to be stereotyped within an individual. Cerebral palsy (CP) seizures can include somatosensory or focal motor features(jerking, loss of muscle tone or repeated movement). CP seizures are associated with altered consciousness . Clinical Presentation and Diagnosis of Epilepsy Cont…. Symptoms… Absence seizures can be almost non-detectable with only very brief (seconds) periods of altered consciousness. GTC (Grand mal seizures )are major convulsive episodes and are always associated with a loss of consciousness. Cerebral palsy is a congenital disorder of movement, muscle tone or posture, it is due to abnormal brain development often before birth Clinical Presentation and Diagnosis of Epilepsy Cont…. Signs Interictally (between seizure episodes), there are typically no objective or pathognomonic signs . Laboratory Tests There are currently no diagnostic laboratory tests for epilepsy. Laboratory tests can be done to rule out treatable causes of seizures (e.g., hypoglycemia, altered electrolyte concentrations, infections, etc.) that do not represent epilepsy . Clinical Presentation and Diagnosis of Epilepsy Cont…. Other Diagnostic Tests EEG(electroencephalogram) is very useful in the diagnosis of various seizure disorders. A prolactin serum level obtained within 10 to 20 minutes of a tonic- clonic seizure can be useful in differentiating seizure activity from pseudo-seizure ( are seizures that occurs as a result of psychological cause such as severe mental stress) activity but not from syncope(loss of consciousness) Magnetic resonance imaging (MRI) is very useful especially imaging of the temporal lobes Activity : Small Group Discussion What is the treatment of Epilepsy? Pharmacological Treatment Of Epilepsy The general approach to treatment involves assessment of seizure type and frequency, identification of treatment goals, development of a care plan, and a plan for follow-up evaluation. During the assessment phase, it is critical to establish an accurate diagnosis of the seizure type and classification in order to select the appropriate initial AEDs . Pharmacological Treatment Of Epilepsy Cont…. Pharmacological Treatment Of Epilepsy Cont…. Pharmacological Treatment Of Epilepsy Cont…. Monitoring of epilepsy Therapy Patients should be monitored long term for seizure control, comorbid conditions, social adjustment, drug interactions, compliance, and adverse effects. Periodic screening for comorbid neuropsychiatric disorders such as depression and anxiety is also important. Clinical monitoring involves identifying the number and type of seizures. Patients should record the severity and the frequency of seizures in a seizure diary. ‘ There should be a decrease in the number and/or severity of seizures. Patients and family should be questioned regularly to determine whether they are truly seizure free . Key Points The term 'epilepsy' is used to define a group of neurological disorders all of which exhibit periodic seizures. Seizures are associated with episodic high-frequency discharge of impulses by a group of neurons (sometimes referred to as the focus ) in the brain. Seizures result from excessive excitation, or in the case of absence