MRI-Negative Epilepsies
The term “MRI-negative” means the absence of an MRI-detectable lesion, while the term “non-lesional” refers to the absence of a specific abnormality on pathological evaluation. During the last years, the quality of MRI has enormously improved facilitating
- PDF / 1,472,616 Bytes
- 14 Pages / 504.567 x 720 pts Page_size
- 77 Downloads / 227 Views
10
Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less. Marie Curie
Contents 10.1
Prevalence
210
10.2 D iagnostics 10.2.1 D iagnostic Tools 10.2.2 D iagnostic Significance 10.3 10.3.1 10.3.2 10.3.3 10.3.4
Surgical Treatment Overall Seizure Outcome Temporal Lobe Epilepsies (TLE) Extratemporal Epilepsies (ETE) Multilobar Epilepsies
References
The presence or absence of a lesion can be based on MRI or on histopathological analysis [1]. In the proper sense, the term non-lesional implies the absence of a lesion not only on MRI, but also in histopathology [2], while the term MRI- negative refers to patients in whom presurgical MRI fails to demonstrate a potentially epileptogenic structural abnormality [3]. Since preoperative decision-making processes are based on MRI as the most precise imaging modality, most studies refer to MRI findings when distinguishing between lesional and non-lesional epilepsies, and in clinical praxis, the terms “non-lesional” and “MRI-negative” are used synonymously [4, 5] In principle, however, the definition of which epi-
210 210 210 213 213 213 215 215 218
lepsies may be called MRI-negative remains dynamic and depends on the technology used and the interpretation of images. Due to advancements in MRI technology and post-processing algorithms, the rate of MRI- negative epilepsies has significantly decreased. Subtle signal deviations and poorly visible lesions are now more clearly identified [6, 7, 8]. The rate of formerly overlooked FCD is likely around 30% [9–11], but rates as high as 41% [12] and 79% [13] have been reported. Automated volumetry and relaxometry analysis have been found to reveal signs of hippocampal sclerosis in 99% of patients with visually detected hippocampal sclerosis, and in 28% with visually normal
© Springer Nature Switzerland AG 2020 J. Zentner, Surgical Treatment of Epilepsies, https://doi.org/10.1007/978-3-030-48748-5_10
209
210
MRI findings [14]. Multi-parametric MRI in adequate angulation using volumetry, FLAIR and T2-weighted fast spin-echo sequences can detect neuronal loss in hippocampal sclerosis with an accuracy approximating histopathological analysis [15, 16]. Furthermore, temporal lobe epilepsy (TLE) coinciding with enlargement of the amygdala has been thought to represent a subtype of TLE that so far is classified as MRI-negative [17]. Therefore, from today’s view, the synonymous use of the terms “MRI-negative” and “non- lesional” seems to be justified, while previous data on the frequency of MRI-negative epilepsies based on uncontrolled imaging quality do not allow this de facto equation.
10 MRI-Negative Epilepsies
36]. Localization of seizure origin is even more challenging in children with MRI-negative epilepsy in whom widespread extratemporal epileptogenesis caused by malformations of cortical development is common. Thus, the lack of an MRI-detectable lesion calls for a more extensive and multimodal presurgical evaluatio
Data Loading...
