I. Overview: Epilepsy is a common condition that has been found in all walks of life from ancient times to the present day. It is said that Van Gogh and Prince Charles II suffered from epilepsy. In ancient times, people have always associated epilepsy with superstition because of the limitations of scientific knowledge. Nowadays, most patients have been able to be cured.
Definition: Epilepsy is a chronic brain disorder characterized by sudden, recurrent and transient central nervous system malfunction caused by excessive neuronal discharge in the brain. Depending on the location of the offending neurons and the extent of the spread of the discharge, the malfunction may manifest as different disorders of movement, consciousness, behavior, autonomic nerves, or both.
III. Classification.
(a) Partial seizures are the first clinical and EEG changes suggesting that the beginning neuronal activation is limited to a part of one cerebral hemisphere.
1. Simple partial seizures without impairment of consciousness. Focal discharges can be recorded on the EEG during or between seizures in the corresponding representative areas on the opposite side of the brain.
(1) Seizures with motor symptoms
(2) Seizures with somatosensory or specific sensory symptoms
(3) Seizures with autonomic symptoms
(4) Seizures with psychiatric symptoms
2. Complex partial seizures with impaired consciousness and unilateral or bilateral asynchronous EEG discharges during seizures, usually located in temporal or frontal areas.
(1) Simple partial seizure onset followed by impaired consciousness
(2) Onset from impaired consciousness
(3) Partial seizures progress to secondary generalized seizures when the EEG is partial seizure discharges, which become diffuse secondary and rapidly.
(2) Generalized seizure is the first clinical change suggesting simultaneous involvement of both hemispheres from the beginning. Impaired consciousness can be the earliest manifestation, and the motor symptoms and EEG changes of the seizure are bilateral, which may reflect the wide distribution of neural discharges in both hemispheres.
1.Aphasic seizures
(1) The EEG during a typical anhedonia attack is a regular and synchronous symmetrical 3-Hz spike-slow complex wave or multiple spike-slow complex waves. The background activity of EEG is normal between seizures, but there may be paroxysmal activity (such as spike wave or spike-slow complex wave).
(2) The EEG is more disorganized during atypical aphasic seizures, including irregular spike-slow complex waves, fast activity or other paroxysms.
(2) The EEG during myoclonic seizures is multiple spike-slow complex waves, or sometimes spike-slow complex waves or spike-slow complex waves. The EEG between seizures is the same as during seizures.
3. The EEG of clonic seizure is fast activity (above 10Hz) and slow waves, occasionally spike-slow complex waves.
4. The EEG of tonic seizure is low amplitude fast activity or fast rhythm above 9~10Hz during seizure, with decreasing frequency and increasing amplitude. Between seizures, different degrees of rhythmic spike and slow complex wave discharges are seen, sometimes asymmetrical, and the background activity is often abnormal.
5.Tonic clonic seizure (grand mal seizure) is a rhythm of 10Hz or more in the EEG during seizure, with decreasing frequency and increasing amplitude in the tonic phase, and excessive spike wave. The spike wave alternates with the slow wave during the clonic phase.
6.Dystonic seizure EEG is multi-spike slow complex wave or low flat or low amplitude fast activity during seizure. Between seizures, it is multi-spike and slow complex waves. If only excitation occurs in the brain, all neurons eventually generate electricity together, resulting in a “discharge storm”. However, some neurons release chemicals from their axons to inhibit surrounding neurons, causing them to stop “generating” electricity. When excitation and inhibition are in balance, the brain works normally.
Diagnostic imaging: CT, MRI, PET, MEG Functional: EEG, magnetoencephalography Xiaohua Bu, Department of Functional Neurosurgery, Xi’an Red Society Hospital
(I) CT
1.Definition CT (X-ray electron computed tomography) is the use of X-ray tomography, received by photon detectors, and the signal is converted into digital input into the computer, and then converted into images by the computer.
2, characteristics of painless, non-invasive, non-hazardous, fast, convenient, suitable for any age and high accuracy.
(B) MRI
1, the definition and principle of MRI (magnetic resonance imaging) imaging principle is achieved through the action of high-frequency magnetic field outside the body, the signal generated by the radiation of energy from the body material to the surrounding environment. A large strong magnet is placed around the head, and the atoms in the brain are aligned along this magnetic field, and then radiofrequency currents are issued, and the hydrogen atoms in the brain resonate. When the hydrogen atoms gradually return to their resting state, they emit radio frequency waves, which are picked up by the “receiver” and analyzed by a computer to produce a detailed picture of the brain.
2.Features
(1)Ionization radiation has no radioactive damage to brain tissue and no biological damage.
(2) It can make transverse segmental, sagittal, coronal and various oblique body layer images.
(3)It is not disturbed by bone image and shows the pathological process of the disease more extensively than CT.
(4) No detection of intracranial calcification
(5) It cannot show metal objects in the brain and certain types of aneurysm clips.
3. Clinical applications (epilepsy) MRI is used to detect structural brain lesions secondary to epilepsy and, during surgery, to help physicians determine the tissue to be removed and the extent of removal.
(C) SPECT 1. Definition Single photon emission computed tomography (SPECT) is a diagnostic technique that applies nuclide to CT.
The basic principle of SPECT is to take radionuclides that can emit pureã photons, aim the probe of the visualizer collimator at the part to be examined, accept the rays from the examined part or organ, amplify the photoelectric pulse through the photomultiplier tube, transform it into a signal, and collect information continuously by computer for image processing and reconstruction.
3.Features
(1) The application of ordinary nuclide can obtain three-dimensional imaging
(2) The localization of epilepsy is much better than CT, MRI and EEG.
(iv) PET
1. Definition and principle of positron emission tomography (PET) is a technique to study physiological processes in the human body. It is the introduction of radionuclide markers emitting positrons into the body, and the stereoscopic distribution of radionuclides in the internal organs is taken up in vitro with a detector, and the tomographic images of the organs are obtained by computerized integrated processing and reconstruction of the images.
2.Features
(1) Unlike CT and MRI, PET image is not only a structural image but also a functional image.
(2) It can respond to the physiological and biochemical changes of organ tissues
(3) It can detect cerebral blood flow, blood volume, amino acid synthesis, protein synthesis, ammonia neurotransmitter metabolism, oxygen and glucose metabolism rate.
(3) Clinical application (epilepsy) PET is used for the study of brain pathophysiology of epileptic patients and other neurological diseases. It is very helpful for preoperative localization.
(V) MEG
1. Principle of magnetoencephalography (MEG) Due to the movement of all the excitatory cell membrane charges, current and magnetic field are generated. The intracellular current can be regarded as a source of magnetic field outside the head. With the conception of a non-concentric circular conductor as a model for the head, the source of the starting current is quickly confined to the surface and produces a measurable magnetic field outside the head.
2. Instruments: superconducting quantum interferometer (SQUID), etc.
3. Difference between MEG and EEG (1) MEG is able to examine the normal and pathological currents in three dimensions within the skull.
(2) Since electromagnetic fields are not reduced by the high impedance of the skull, MEG is more sensitive than EEG, especially when observing subcortical activity.
(3) Electromagnetic theory states that only intracellular currents generate currents in the extracellular space, whereas EEG is the result of these volumetric currents.
V. When treating seizures, there are many treatments that can prevent serious injury to the patient if some simple steps are applied, while medication and surgery can reduce the number of seizures.
1. general rescue treatment of epilepsy treatment of convulsions avoidance of triggers long-term treatment
2, medication medication is the core problem of epilepsy different seizure types take different drugs drugs often produce side effects
3, surgical treatment
Prerequisite: intractable epilepsy
Intractable epilepsy refers to frequent seizures, more than once a month, with more than three types of antiepileptic drugs correctly selected for regular treatment, no intolerable side effects, and blood concentration in the effective range; persistent treatment for more than two years still cannot control the seizures.
The main issues: comprehensive localization of the epileptogenic focus, patient selection and surgical approach.