British Society for Clinical Neurophysiology / Clinical Neurophysiology 118 (2007) e141–e144
and a reduced bradykinesia, but gait freezing was observed on the right side with stimulation. A repeat MRI revealed the left DBS electrode to be in the red nucleus. The electrode position was subsequently readjusted with excellent clinical result. To our knowledge no human red nucleus recording and stimulation has previously been performed. The eﬀects on parkinsonism were similar to those STN stimulation gave for gait freezing.
return of rhythmic synchronised action potential ﬁring. The experiments demonstrate that depolarisation block has a role interrupting population spike discharges in the low calcium model of epilepsy and we speculate that it could play a role in generating the localised electrodecremental events seen in clinical epilepsy. doi:10.1016/j.clinph.2006.07.188
Audit of the Paediatric Epilepsy Surgery Programme—P. Chorlton (Frenchay Hospital, Bristol, UK)
Thalamic recordings and stimulation in myoclonic dystonia—A. Forster, T.R.K. Varma, P. Eldridge, H. Tyne, H. Cameron, M.J. Steiger (The Walton Centre, Liverpool, UK) Thalamic deep brain stimulation (DBS) is an eﬀective treatment for tremor due to a variety of causes. It has also been used in dystonia, though normally the globus pallidus is more eﬀective in this type of problem. In the rare genetic condition of myoclonic dystonia thalamic stimulation has been successfully used (Kupsch et al. 1999), also pallidal stimulation (Liu et al. 2002). We wish to report unusual cellular signals recorded during insertion of DBS electrodes into the thalamus. A 36-year-old patient with myoclonic dystonia had suﬀered disabling involuntary jerking movements since his teenage years. Microelectrode recording from the thalamus (FHC microelectrode, Leadpoint) was performed to aid localisation of the DBS electrode. Cells in the thalamus had a very unusual sound, with decelerating, high frequency bursts, from 500 to 300 Hz, lasting approximately 100 ms. These cellular signatures have not been previously described, and are, in our experience, unique. They may aid the interpretation of the pathological processes in this fascinating condition. The patient, with his DBS electrodes in place, has regained much of his independence.
Retrospective audit was undertaken on all patients who underwent video EEG recording as part of the Paediatric Epilepsy Surgery Programme between its inception in September 1999 and July 2002. Total patient number was 37, with an age range of 2–15 years. EEG results were divided into normal or abnormal. Abnormalities were classiﬁed into 3 groups-localised/lateralised, generalised changes or mixed pattern. Ten patients did not have attacks during the monitoring period (average 48 h). AED reduction was undertaken in 4 out of the 10 patients. Sixteen patients had clinical events that were not accompanied by EEG changes. Twentyﬁve patients had clinical events associated with EEG changes, and AED reduction was undertaken in 8 of the 25. Only 2 patients had normal EEGs, 18 had localised/lateralised abnormalities, 6 had generalised changes and 11 had mixed patterns of abnormality. Twenty-four patients were referred for surgery; 12 for VNS, 8 lesionectomy, 1 callosotomy and 1 had callosotomy with lesionectomy and VNS (2 cases surgery type remains undecided). 10/12 VNS referrals had mixed/generalised EEG abnormality, whilst all lesionectomy referrals had localised/lateralised abnormality. The callosotomy patients had mixed/generalised abnormality. In conclusion, Video EEG recording is an essential investigation in any Paediatric Epilepsy Programme and valuable in tailoring surgery.
Depolarisation block underlies the interruption of synchronised neuronal discharges in the low calcium model of epilepsy—J.F. Fox, M. Bikson, J.G.R. Jeﬀerys (University of Birmingham, UK)
An interesting case study of periodic complexes—R. Madden, S. Bhath, D.G. Rao (Queen Elizabeth Hospital, Birmingham, UK)
The isolated hippocampal slice, exposed to artiﬁcial CSF with a Ca concentration <0.2 mM, generates episodes of spontaneous, rhythmic synchronised action potentials which resemble electrographic seizures. Since synaptic transmission is blocked, this preparation allows investigation of non-synaptic mechanisms which may contribute to epilepsy. We classiﬁed these episodes of ‘‘epileptiform’’ activity into types I–III, depending on synchronised discharges being present for 90–100%, 10–90% or 0–10% of the event, and investigated how spike generation is interrupted in types II and III. Intracellular recordings showed that neurons were not only depolarised during the initial phase of the event, when they generated action potentials, but also throughout the period when spike generation was interrupted. Hyperpolarising the neurons (via intracellular electrodes or by DC ﬁelds applied across the slice) induced a
Periodic complexes that present with rapidly progressive dementia are often associated with sporadic Creutzfeldt–Jakob disease (CJD). We report an interesting case study showing characteristic periodic complexes where a query of CJD was raised. We collated data and pictorial representation from notes, MRI scans, EEG graphs and the post- mortem studies. Periodic complexes are seen in a number of disorders and it is impossible without a good medical background to associate these accurately with a diagnosis. Also repeat EEGs are of great significance when a suspected diagnosis of CJD is entertained. We found at post-mortem that this patient did not in fact have prion disease and the repetitive complexes were due to multiple embolic infarcts secondary to bacterial endocarditis. doi:10.1016/j.clinph.2006.07.190