epilepsy Flashcards
what is epilepsy?
The term epilepsy includes disorders or syndromes with widely variable pathophysiologic ndings, clinical mani- festations, treatments, and outcomes.1 Epilepsy is not a speci c diagnosis but rather a term that refers to a group of disorders characterized by chronic and recurrent, paroxysmal changes in neurologic function (seizures), altered consciousness, or involuntary movements caused by abnormal and spontaneous electrical activity in the brain. Seizures may be convulsive (i.e., accompanied by motor manifestations) or may occur with other changes in neurologic function (i.e., sensory, cognitive, and emotional).2
how are seizures characterized?
Seizures are characterized by discrete episodes, which tend to be recurrent and often are unprovoked, in which movement, sensation, behavior, perception, and con- sciousness are disturbed. Symptoms are produced by excessive temporary neuronal discharging, which may result from intracranial or extracranial causes.3
Although seizures are required for the diagnosis of epilepsy, not all seizures imply presence of epilepsy. Sei- zures may occur during many medical or neurologic illnesses, including stress, sleep deprivation, fever, alcohol or drug withdrawal, and syncope.3 A list of epilepsy syndromes and the currently accepted classi cation of seizure types are presented in Box 27-1. This seizure classi cation, based on clinical behaviors and electroen- cephalographic changes, consists of two major groups: partial and generalized. Partial seizures are limited in scope (to a part of the cerebral hemisphere) and clinical manifestations and involve motor, sensory, autonomic, or psychic abnormalities.3 Partial seizures are subdivided into simple, in which consciousness is preserved, and complex, in which consciousness is impaired. General- ized seizures are more global in scope and manifesta- tions. They begin diffusely, involve both cerebral hemispheres, are associated with alteration in conscious- ness, and frequently produce abnormal motor activity.3 Discussion in this section is limited to generalized tonic- clonic seizures (idiopathic grand mal), because these rep- resent the most severe expression of epilepsy that the dentist is likely to encounter.
what is the pathophysiology and complications associated with epilpepsy?
The basic event underlying an epileptic seizure is an excessive focal neuronal discharge that spreads to tha- lamic and brain stem nuclei. The cause of this abnormal electrical activity is not precisely known, although a number of theories have been put forth.2,3 These include altered sodium channel function, altered neuronal mem- brane potentials, altered synaptic transmission, diminu- tion of inhibitory neurons, increased neuronal excitability, and decreased electrical threshold for epileptic activity. During the seizure, blood becomes hypoxic, with conse- quent development of lactic acidosis.2,3
Approximately 60% to 80% of patients with epilepsy achieve complete control over their seizures within 5 years; the remainder achieve only partial or poor control.2,3,5 A signi cant problem in the medical manage- ment of epileptic patients is one of compliance (i.e., adherence to prescribed treatment regimens including medication). This problem is common to many chronic disorders, such as hypertension, because patients may have to take medication for the rest of their lives, even though they remain asymptomatic. Evidence suggests that patients who have epilepsy from an early age have a higher incidence of future complications and die at an earlier age. Noncompliance may be a clinically impor- tant consideration in dental patients because it is associ- ated with a higher risk of later complications that may lead to death.4 Complications of seizures include trauma (as a result of falls) to the head, neck, and mouth and aspiration pneumonia. Also, frequent and severe seizures are associated with altered mental function, dullness, confusion, argumentativeness, and increased risk of sudden death (about 1 in 75 persons in this group die annually).2,3
Status Epilepticus. A serious acute complication of epilepsy (especially the tonic-clonic type) is the occur- rence of repeated seizures over a short time without a recovery period, called status epilepticus. This condition most frequently is caused by abrupt withdrawal ofanticonvulsant medication or an abused substance but may be triggered by infection, neoplasm, or trauma. Status epilepticus constitutes a medical emergency.2,3 Patients may become seriously hypoxic and acidotic during this event and suffer permanent brain damage or death. Patients with epilepsy also are at increased risk for sudden death and death due to accident.2,3
