Paired pulse. Reduced SICI has been reported in untreated focal epilepsy patients in the ipsilateral compared to the contralateral hemisphere and healthy controls, (Xxxxxx et al., 2007) Other studies are not convergent, (Xxxxx et al., 2005a)showed no changes in SICI compared to controls, however compared with patients with temporal epilepsies, patients with extratemporal epilepsies showed an apparent increase in ICF bilaterally. To further confuse matters, bilaterally decreased ICF has been reported in 13 untreated patients with focal epilepsy compared with controls (Xxxxxxx et al., 2000). In addition, patients with focal epilepsy who were withdrawn from their medication for 48 hours have been reported to show reduced SICI and ICF in the hemisphere ipsilateral to seizure onset (Xxxxxx et al., 2006). In an analysis of LICI in patients with untreated focal epilepsy, a significant increase in cortical excitability at the 250 and 300 ms XXXx compared to controls has been observed in the ipsilateral hemisphere (Xxxxxx et al., 2007, Xxxxxx et al., 2010a, Xxxxxx et al., 2006). Overall the results from paired pulse seem to be extremely conflicting, however a pattern of differences in TMS parameters potentially mediated by GABAergic mechanisms between patients on AEDs, both medicated and drug naïve, in comparison to controls is apparent. The findings of TMS studies in focal epilepsy are summarised in Table 4.
Paired pulse. Paired pulse TMS has indicated reduced SICI in untreated patients with IGE in both drug naïve, (Xxxxxx et al., 2007) and medicated patients (Xxxxxxxxxx et al., 2000). Conflicting results of increased SICI have been observed in AED medicated patients, (Xxxxxxx et al., 1996). In one study of patients with JME, a significant reduction in SICI was seen in both treated and untreated patients. In a study on untreated patients tested within 48 hours of their first GTCS, SICI was normal, but ICF was decreased, which was interpreted as a protective mechanism against further seizures, (Delvaux et al., 2001). A summary of TMS measures in generalised epilepsy can be found in Table 5. TMS then can be used to assess the functional integrity of cortical circuits and the pathophysiology of epilepsy in vivo. Results have been generally divergent, partially perhaps due to medications, especially in relation to motor thresholds in which the impact of sodium channel blocking medications must be seriously considered. It is important to emphasise therefore that in this thesis a consideration of drug burden was made when making group comparisons. Table 4 Summary table of TMS in focal epilepsy AUTHOR AND YEAR DETAILS OF PATIENT GROUP AND SYNDROME STUDIED MAIN FINDINGS OF PATIENTS’ RECORDINGS IN COMPARISON TO HEALTHY CONTROLS (Xxxxxxxx et al., 1998) Cryptogenic epilepsy: 8 with motor cortex epilepsy vs 10 with no clonic activity and controls. CSP 🡩 in epilepsy involving motor cortex vs other 2 groups (Xxxxxxxx et al., 18 cryptogenic focal on 🡩RMT 🡩 SICI in right 2000)(Inghilleri et al. medication hemisphere 1998) (Xxxxxxxxx et al., 2000) 16 cryptogenic partial epilepsy (medicated) CSP at differing stimulus intensities 🡫 inhibition in ipsilateral (Xxxxxxx et al., 2000) 15 temporal and extratemporal. (No AEDs taken <48 hours). 🡫SICI (contralateral) and ICF (ipsilateral) (Xxxxxxxxx et al., 2004) 110 cryptogenic partial 🡩 MT in patients in general epilepsy & in polytherapy vs monotherapy. (Xxxxxxx et al., 2004) 21 partial cryptogenic (unmedicated) 🡩SICI in patients with more frequent IEDs (Xxxxx et al., 2005a) 23 focal (14 temporal, 9 extratemporal). 🡫 CSP 🡩 SICF in ipsilateral vs contralateral, more pronounced in extratemporal. (Xxxxxx et al., 2006) 18 TLE. Patients with seizures in following 24 hrs showed 🡫 SICI and ICF (Xxxxxx et al., 2007) 27 drug-naïve focal (unilateral foci) 🡩 MT in ipsilateral vs contralateral hemisphere (Xxxxxx et al., 2009b) 35 focal 🡩 MT and SICI...
