In the terminal phase of the seizure, all movements end and the patient is motionless and limp in a deep coma. The pupils begin to contract to light. Breathing may be quiet or stertorous. This state persists for several minutes, after which the patient opens his eyes, begins to look about, and appears bewildered and is confused and may be quite agitated. The patient may speak and later not remember anything that has been said and undisturbed becomes drowsy and falls asleep, sometimes for several hours, then often awakens with a pulsatile headache. When fully recovered, such a patient has no memory of any part of the spell but knows that something has happened because of the strange surroundings (in ambulance or hospital), the obvious concern of those around him, and often, a sore, bitten tongue and aching muscles from the violent movements. The convulsive contractions, if violent enough, may crush a vertebral body or result in a serious injury; a fracture, periorbital hemorrhages, subdural hematoma, posterior shoulder dislocation, or burn may have been sustained in the fall.
Each of these phases of the generalized tonic-clonic seizure has characteristic EEG accompaniments. Initially, movement artifacts obscure the EEG tracing; sometimes there are repetitive spikes or spike-wave discharges lasting a few seconds, followed by an approximately 10-s period of 10-Hz spikes. As the clonic phase asserts itself, the spikes become mixed with slow waves and then the EEG slowly assumes a polyspike-and-wave pattern. When all movements have ceased, the EEG tracing is nearly isoelectric for a variable time, and then the brain waves gradually resume their preseizure pattern.
Severe seizures may be accompanied by a systemic lactic acidosis with a fall in arterial pH, reduction in arterial oxygen saturation, and rise in PCO2. These effects are secondary to the respiratory arrest and excessive muscular activity. If prolonged, they may cause hypoxic-ischemic damage to remote areas in the cerebrum, basal ganglia, and cerebellum. In paralyzed and artificially ventilated subjects receiving electroconvulsive therapy, these changes are less marked and the oxygen tension in cerebral venous blood may actually rise. Heart rate, blood pressure, and particularly CSF pressure rise briskly during an ECT-induced seizure. According to Plum and colleagues, the rise in blood pressure evoked by a seizure usually causes a sufficient increase in cerebral blood flow to meet the increased metabolic needs of the brain.
Convulsions of this type ordinarily come singly or in groups of two or three and may occur when the patient is awake and active or during sleep, or when falling asleep or awakening. It is useful to know that seizures on awakening usually signify a generalized type, whereas those occurring during the period of sleep are more often focal in nature. Some 5 to 8 percent of such patients will at some time have a prolonged series of such seizures without resumption of consciousness between them; this is status epilepticus and demands urgent treatment. The first outburst of seizures in an individual may take the form of status epilepticus.