Solomon
thanks for this...... can't help but wonder if Neurofeedback and/or HEG
wouldn't achieve the same effect in a kinder and gentler fashion.
mjh

> Date: Mon, 10 Nov 2003 02:07:14 -0000
> From: "Solomon Cobbs" <solcobbs@...>
> Subject: BRAIN STIMULATION OFFERS HOPE FOR SOME PATIENTS WITH EPILEPSY
>
> BRAIN STIMULATION OFFERS HOPE FOR SOME PATIENTS WITH EPILEPSY
>
> http://www.neurologyreviews.com/oct01/nr_oct01_epilepsy.html
>
> CLEVELAND—Two methods of cerebral stimulation seem to be expanding
> their therapeutic utility. While the majority of clinical experience
> with deep brain stimulation (DBS) has been in patients with
> Parkinson's disease and essential tremor, speakers at the Cleveland
> Clinic Foundation's Neuromodulation Symposium told of extending its
> use to other groups of patients, including those with epilepsy who
> are refractory to medications and are not surgical candidates.
> Likewise, transcranial magnetic stimulation (TMS), which is currently
> used to treat conditions ranging from depression to cerebral
> ischemia, offers a more problematic but potentially promising method
> of reducing epileptic seizure frequency.
>
> DEEP IMPACT
>
> Alim-Louis Benabid, MD, of the University Joseph Fournier, Grenoble,
> France, said that patients with epilepsy selected for DBS include
> those who are medically resistant and those who cannot be operated on
> because seizure foci are too close to vital structures. Dr. Benabid
> said DBS has caused "dramatic improvement" in some of these cases and
> lesser improvements in others.
>
> Likewise, Hans Lüders, MD, PhD, of the Cleveland Clinic Foundation,
> listed the hippocampus, mammillary bodies, and cingulate gyrus as
> some of the successful targets for DBS seizure inhibition, but he
> allowed that stimulation of the caudate in these patients has
> had "mixed reviews."
>
> More wholly positive results were garnered by Andres Lozano, MD, PhD,
> of the University of Toronto. Dr. Lozano reported that five patients
> with generalized or complex partial seizures who received anterior
> thalamic stimulation had a 93% reduction in their seizures. "The
> mechanism of action of DBS in epilepsy patients is unclear," he
> said, "but it may be that the stimulation is of cell bodies or
> axons." The fact that some patients lost their seizures altogether
> for several months after the stimulator was turned off without their
> knowledge also suggests that the DBS affects brain plasticity.
>
> CENTROMEDIAN THALAMIC NUCLEI—SEIZURE CENTERS?
>
> During the past 15 years, Francisco Velasco, MD, and colleagues at
> the General Hospital of Mexico and the Technological Institute of
> Mexico have been treating patients with hard-to-control seizures who
> are not candidates for conventional ablative procedures. Dr. Velasco
> defines such patients as those with "mainly generalized seizures
> without evidence of focal onset, such as cases of Lennox-Gastaut
> syndrome, as well as cases with a multifocal onset of seizures,
> particularly those with bitemporal or bifrontal independent foci."
>
> These patients are treated with bilateral implanted electrodes in
> both centromedian thalamic nuclei, using intermittent, alternating,
> bilateral stimulation because of evidence that the intralaminar and
> midline thalamic nuclei "participate in both the genesis and
> propagation of seizure activity." Dr. Velasco added that the
> centromedian area was chosen because it is "a large nucleus, placed
> immediately above and in front of easily recognized stereotactic
> landmarks such as the anterior commissure/posterior commissure line
> and the vertical line touching the anterior border of the posterior
> commissure."
>
> Electrode placement was done under general anesthesia, using
> ventriculography control. Correct placement of the electrodes was
> verified "by simple electrophysiological techniques." Inappropriate
> placement of electrodes, with a lateral or posterior deviation from
> the trajectory of the electrodes, may also be determined by the fact
> that they can cause paresthesia or pain.
>
> "Once the corroboration has been made, the electrodes are connected
> to internalized pulse generators placed in subcutaneous pockets in
> each subclavicular region," Dr. Velasco said. A sub-acute trial
> conducted during a two- to four-week period will decrease seizures
> and paroxysmal discharge and in most cases yield a long-term
> favorable result. Overall, the best results were obtained from
> patients with Lennox-Gastaut, who demonstrated a highly significant
> decrease in tonic-clonic and atypical absence
> seizures. "Simultaneously," Dr. Velasco added, "generalized spikes,
> spike wave complexes, and bilateral synchronous discharges are
> significantly decreased." Focal temporal spikes, however, are not
> decreased, and DBS had little efficacy on complex partial seizure
> patients.
>
> In another study, Dr. Velasco reported that continuous stimulation of
> the epileptic focus was given to 10 patients scheduled for temporal
> lobectomy. Treatment lasted for 10 to 15 days, while the patients
> were off drugs. Quantification of the number of seizures and
> interictal spikes at the epileptic focus indicated that low-
> intensity, high-frequency stimulation of temporal lobe foci did
> result in a significant decrease in clinical seizures and in
> interictal spikes.
>
> After the trial an en bloc resection of the hippocampus and
> parahippocampal and fusiform cortices was done in order to compare
> receptor binding density of those who underwent brain stimulation
> with those of patients who underwent lobectomy but did not have
> preoperative stimulation, and also with autopsy cases of patients
> with no history of neurologic disorders. Benzodiazepine receptor
> binding density was found to be significantly lower in the temporal
> lobe of seizure patients than in non-epileptic specimens, although
> DBS partially restored receptor binding in the parahippocampal
> cortex, "which may be the mechanism to control epileptic activity,"
> Dr. Velasco noted.
>
> TRANSMAGNETIC STIMULATION—THE WAVE OF THE FUTURE?
>
> Yet another approach to the treatment of epilepsy is transcranial
> magnetic stimulation over the epileptic foci. Mark Hallett, MD, of
> the National Institute of Neurological Disorders and Stroke, said
> there have been some promising animal studies, and now some human
> studies in a small number of patients, although he described the use
> of TMS for various neurologic disorders as being "not yet ready for
> prime time."
>
> TMS produces a brief, high-current pulse in a circular wire, which is
> called the magnetic coil. The mechanism of action, Dr. Hallett said,
> is the production of a magnetic field with lines of flux passing
> perpendicularly to the coil. Perpendicular to the magnetic field, an
> electric field is induced. The magnetic coils may be produced in
> different shapes. Round coils are relatively powerful, Dr. Hallett
> explained, but figure-eight coils, on the other hand, are "more
> focal, producing maximum current at the intersection of the two round
> components."
>
> Two main types of TMS are being considered for treatment purposes.
> Single pulse TMS, used mainly in research, has been shown to be very
> safe. Repetitive (from more than 1 to 30 Hz) TMS, or rTMS, can
> produce seizures even in normal individuals, although there are
> published safety guidelines which should prevent this, Dr. Hallett
> said. There appears to be no lasting effect for single pulses of TMS,
> although rTMS can have a lasting effect.
>
> In 1999, a pilot study cohort of nine patients with frequent partial
> or tonic-clonic seizures had rTMS applied on five consecutive days,
> using two trains of 500 pulses applied through a 9-cm diameter round
> coil placed over the vertex of the skull. Eight of the nine described
> an improvement in the number or severity of seizures, or both. The
> number of seizures per week declined to 5.8 from 10.3.
>
> Unfortunately, current implementation of TMS is limited because
> it "affects only the superficial cortex, and the physics dictates
> that it will never be possible to stimulate more than superficially."
> Dr. Hallett remains hopeful, however, that "it may be possible to
> develop coils that stimulate at greater depth."
>
> NR
>
> —Jean McCann
>



MJH


[Non-text portions of this message have been removed]