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[Less invasive treatment of intractable epilepsy--vagus
nerve stimulation and stereotactic radiosurgery]
[Article in Japanese]
Department of Neurosurgery,
GraduateSchool of Medicine, University of Tokyo, 7-3-1 Hongo,
Bunkyo-ku, Tokyo, Japan.
Vagus nerve stimulation (VNS) and
stereotactic
radiosurgery (SRS) represent novel and less invasive therapeutics for
medically intractable epilepsy. VNS ushered in the recent advancement
in clinical application of electrical stimulation therapy for epilepsy.
Chronic stimulation of the left vagus nerve with implanted generator
and electrodes inhibits seizure susceptibility of the cerebral
cortices. Its efficacy and safety have been established by randomized
clinical trials in 1990s in the Western countries and it has been
widely accepted as a treatment option for patients with medically
intractable epilepsy for whom brain surgery is not indicated or failed.
Although the effect on seizures is not so dramatic, the less
invasiveness and a wide range of indication have made VNS indispensable
for comprehensive care of epilepsy. Since the devices are not approved
for clinical use in Japan, there exist barriers to provide VNS to
patients at present. Use of SRS for intractable epilepsy started in mid
90s as gamma knife surgery for mesial temporal lobe epilepsy. The
marginal dose of 25 Gy to the medial temporal structures has been
confirmed to be effective for seizure control, but there seems to be an
unignorable risk of brain edema and radiation necrosis. It is still
controversial whether the therapy is more effective and less invasive
than brain surgery. A randomized clinical trial using the dose of 20 or
24 Gy is ongoing in the United States. SRS for intractable epilepsy
associated with hypothalamic hamartoma has been advocated because of a
high surgical morbidity, but further study is needed for
standardization of the treatment. Substitute use of SRS for other
surgical technique like callosotomy or disconnection of epileptic focus
seems to be another direction worth pursuing.
PMID: 17447516 [PubMed - in process]
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