Hippocampal sclerosis

Hippocampal sclerosis Common causes of Epilepsy MRI epilepsy protocol • Mesial temporal sclerosis (MTS), also commonly referred to as hippocampal sclerosis, is the most common association with intractable temporal lobe epilepsy (TLE) It is seen in up to 65% of autopsy studies, although significantly less on imaging Etiology • • Controversy exists as to the causative mechanism: is mesial temporal sclerosis a result of temporal lobe epilepsy or vice versa? It is widely considered an acquired phenomenon, secondary to postnatal injury such as prolonged febrile seizures (FS) Hippocampus anatomy • • • • • Annotations: green arrows: parahippocampal gyrus red arrows: tentorium cerebelli yellow arrows: collateral sulcus blue arrows: hippocampus (immediately below the floor of the temporal horn of the lateral ventricle, best imaged in the coronal plane) Radiographic features • • Although comparing left to right side is easiest, it must be remembered that up to 10% of cases are bilateral Bilateral mesial temporal sclerosis is difficult to detect due to the lack of comparison with the unaffected contralateral hippocampus Often mentioned, least specific findings, is enlargement of the temporal horn of the lateral ventricle MR spectroscopy • • • MR spectroscopy findings typically represent neuronal dysfunction : decreased NAA and decreased NAA/Cho and NAA/Cr ratios increased lipid and lactate soon after as seizure MR perfusion • MR perfusion demonstrates 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 In interictal periods, conversely, perfusion is reduced • In 15% of patients another developmetal abnormality can be found, mostly focal cortical dysplasia This is called dual pathology Treatment and prognosis • • TLE is initially managed medically with anti-epileptic agents In patients who are refractory to medical management temporal lobectomy or selective amygdalohippocampectomy may be performed Surgical removal of visible MRI changes associated with unilateral mesial temporal sclerosis leads to seizure freedom in up to 80% of cases Conclusion • Mesial temporal sclerosis and focal cortical dysplasia are the most common causes and can only be depicted with a dedicated protocol • Reduced hippocampal volume, increased T2 signal, enlargement of the temporal horn of the lateral ventricle/ coronal plane • anti-epileptic agents, Surgical removal  ...Common causes of Epilepsy MRI epilepsy protocol • Mesial temporal sclerosis (MTS), also commonly referred to as? ?hippocampal sclerosis, is the most common association with intractable temporal... MRI changes associated with unilateral mesial temporal sclerosis leads to seizure freedom in up to 80% of cases Conclusion • Mesial temporal sclerosis and focal cortical dysplasia are the most... as prolonged febrile seizures (FS) Hippocampus anatomy • • • • • Annotations: green arrows: parahippocampal gyrus red arrows: tentorium cerebelli yellow arrows: collateral sulcus blue arrows: hippocampus