In most patients, the epileptogenic focus involves the structures of the mesial temporal lobe (illustrated in the diagrams below). These structures. Esclerose mesial temporal consiste em perda neuronal, demonstrada nos métodos de neuro-imagem, sobretudo pela RM, pela atrofia e alteração da. Surgical removal of visible MRI changes associated with unilateral mesial temporal sclerosis leads to seizure freedom in up to 80% of cases.
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Mesial temporal sclerosis | Radiology Reference Article |
Mesial temporal sclerosis MTSalso commonly referred to as hippocampal sclerosisis the most temporzl association with escelrosis temporal lobe epilepsy TLE 2,3,5. Most patients present with complex partial temporal lobe epilepsy.
The relationship, if any, of mesial temporal sclerosis with febrile seizures is controversial, made all the more difficult due to the relative insensitivity of imaging and the difficulty in establishing whether a particular seizure was truly febrile. Up to a third of escleroxis with established refractory temporal lobe epilepsy have a history of seizures in childhood at the time of fever 3.
Follow up of children with febrile seizures does not demonstrate significant increased incidence of temporal lobe epilepsy 3. The hippocampal formation is not uniformly affected, with the dentate gyrusand the CA1, CA4 and to a lesser degree CA3 sections of the hippocampus being primarily involved 4.
Histologically there is neuronal cell loss, gliosis and sclerosis. Controversy exists as to the causative mechanism: MRI is the modality of choice to evaluate the hippocampus, however dedicated TLE protocol needs to be performed if escleerosis sensitivity and specificity is to be achieved 5.
Thin section angled coronal sequences at right angles to the longitudinal axis of the hippocampus are required, to minimise volume averaging. Often mentioned, but probably one of the least specific findings, is enlargement of the temporal horn of the lateral ventricle 5. If anything, care must be taken not to allow an enlarged horn to trick you into thinking the hippocampus is reduced in size.
Additional 3D volumetric studies can be performed, and although time consuming to post-process may be more sensitive to subtle esclerpsis volume loss. Gadolinium is not required 5. T2 relaxometry may also be useful in detecting cases of hippocampal sclerosis 5. As a result of neuronal loss, the extracellular space is enlarged and thus diffusion of water molecules is greater on the affected side, resulting in increased values on the affected side higher signal on ADC.
Conversely, due to neuronal dysfunction and swelling, diffusion is restricted following a seizure, and thus values are lower 5. MR perfusion demonstrates similar changes to SPECT see below with blood perfusion depending on when the scan is obtained.
During the peri-ictal phases, perfusion is increased, not only in the mesial temporal lobe but often in large parts of temporal lobe and hemisphere. Other causes of temporal lobe epilepsy TLE should be considered, especially as small temporal lobe cortical tumours can have similar appearances.
Esclerosiis is initially managed medically with anti-epileptic agents. In patients who are refractory to medical management temporal lobectomy or selective amygdalohippocampectomy may be performed.
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