MRI of the brain in epilepsy: what shows?
Epilepsy is a complex neurological disorder which has many different reasons for the occurrence. The disease is paroxysmal during during epidiascope person can lose consciousness, usually develop seizures (epileptic fit). Equivalent to a seizure may be attacks of temporary confusion (small epiprocta) with subsequent amnesia.
To establish the diagnosis «epilepsy» MRI data is optional, the conclusion made by the neurologist (epileptologist), a psychiatrist on the basis of the anamnesis (the patient and his relatives confirmed epileptic seizures or equivalents), objective data and instrumental diagnosis of.
The data of electroencephalography (EEG) reveal the focus of pathological excitation in the brain, which provokes attack. But as an epileptic seizure is only a symptom of a serious pathology of the brain, the detection and treatment of this pathology is impossible without an MRI.
Macro-structural pathology of the brain, which can cause development of seizures
In sixty percent of patients with seizures, the disease occurs on the background of acquired organic pathology of the brain, such epilepsy is symptomatic. In this case, it is necessary to do MRI if the patient in adulthood first emerged attack.
Microstructuring reasons for the development of epilepsy can be:
- Traumatic brain injury.
- Infection of the brain and membranes.
- Chronic intoxication (alcoholism, drug addiction).
- Dystrophic changes.
- Malformation of blood vessels.
- The effects of surgical intervention.
MRI at diagnosis of symptomatic epilepsy shows signs of the above pathologies, which is well visualized in the standard mode of study.
Diagnostic features of chronic epilepsy using magnetic tomography
Diagnostic features of epilepsy using MRI are that, in itself, revealed abnormal formation of the brain may not accurately indicate the presence of epilepsy, as well as the absence of macro-structural pathology on MRI in standard mode may not exclude the disease, as the cause of the disease may be microstructural change of the brain.
Diagnosis of chronic epilepsy (a long time from early childhood) and finding the source of anxiety, is very difficult. The cause of the disease in children is a congenital abnormality of the cerebral cortex or infectious disease.
Difficulties in the diagnosis of structural pathology related to the fact that identifying the source of increased excitability in this case requires the use of special contrast and modes of study (MP-RAGE, VIBE, FLAIR), which are not used in the standard examination of the brain.
For precise diagnosis of the source of anxiety it is necessary to hold more than thin slices (two to three mm) and high power apparatus.
Usually MRI study is assigned a patient with chronic epilepsy specifically, to detect the source of irritation. Often this is necessary when resistant to medical therapy forms of the disease, to resolve the question about surgical treatment.
To improve the efficiency of MRI before the vote, patients perform electroencephalography, which is a hint to the radiologist, what part of the brain to look for the expected focus.
Options the centers of excitation in the brain at a microstructural pathology
Congenital pathology, which is formed in children during gestation. The anomaly is associated with impaired localization of the cortex (gray matter) brain: parts of the gray matter of microscopic size are found among white matter (glia). Atypical is the gray substance may be a focus of excitation of epilepsy.
For the diagnosis of cortical dysgenesia use powerful magnetic scanners (at least half teslow, preferably three and above). Sections make minimal (less than one millimeter), with the ability to generate three-dimensional images.
Hippocampus structural formation in the temporal lobe of the brain. Hippocampal sclerosis may develop in children due to various causes: fever with convulsions, neuroinfection, trauma, blood loss, intoxication.
For diagnostic use the special modes of obtaining images: MP-RAGE, VIBE, FLAIR, as well as changing the plane of the slices, so that it was held parallel to the hippocampus (a variance of 20 – 25% from the standard position). The thickness of the sections should not exceed three millimeters.
Hamartoma of the hypothalamus
Hypothalamus hamartoma – a benign tumor, node, which consists of the same fabric as the hypothalamus. Develops a tumor in children or in utero or in infancy. The causes of the disease are unknown. The tumour is characterized by moderate growth and can’t metastasize, but the presence of such benign tumors can cause epilepsy in children.
The tumor can be identified in standard mode MRI, but the prerequisite is a high contrast image.
Benign glial tumor
For glial tumors, which can cause epileptic seizures include: astrocytomas, oligodendrogliomas and gangliogliomas. Eighty percent of cases these formations are localized in the temporal lobes of the brain. Tumors can occur in children and adults.
For the diagnosis of micropohone required enough power of MRI machine (more than teslow) and thin slices (less than three millimeters).
The role of MRI in the efficiency of surgical treatment of epilepsy
Before the development of MRI diagnostics of epileptogenic areas of the brain could only be detected using electroencephalography. Data this method was not sufficient for effective surgical treatment, therefore, resistant to drug therapy forms of epilepsy that were left without effective treatment, causing the disease progression, which was accompanied by the development of dementia.
Currently, modern MRI can diagnose up to 98% of the centers of excitation. The result is highly accurate and allows you to perform a complete removal of the pathological education.
The latest technology MRI allow us to do the procedure intraoperatively (during surgery) supervising the effectiveness and extent of surgery.
Can be used for diagnostics and computer tomography, for example, in the presence of contraindications to magnetic resonance imaging, but the effectiveness of this method is only 50% and can be used to determine only macropathology.