DBS involves electrical stimulation of specific
subcortical nuclei, which have widespread neural
connections. The anterior nucleus of the thalamus is
often the target of DBS due to its widespread projections
to the limbic system. In a randomized conhad
DBS electrodes implanted in the anterior nucleus
abnormalities apparent on pre-operative imaging studexperience
seizures post-operatively may benefit from
trolled trial of 109 patients with refractory epilepsy who
of the thalamus there was a 29% greater reduction
in seizures for 54 patients who had the stimulator
switched on compared to 55 patients who had
their stimulation turned off after a blinded period
of 3 months (P = 0.002).57 Infection, hemorrhage
and stimulation-induced seizures were amongst the
most frequently reported complications. In the same
study, impaired memory and higher levels of depression
were observed in the group receiving the active
treatment. DBS has been recently licensed in the
UK, and NICE guidelines suggest that this method
should be used in highly selected cases, due to the
lack of efficacy data and the associated risks.58 The
centromedian nucleus is also a potential location for
DBS, since it is part of the reticulo-thalamo-cortical
system which is involved in mediating cortical excitability
and wakefulness. One double-blind crossover
trial reported a 30% reduction in generalized
tonic-tonic seizures when the device was turned on
compared to when it was off, although this change
was not significant, possibly due to the small sample
size of 7 patients.59 Further evidence for centromedian
nucleus stimulation efficacy can be found in a
longitudinal study which reported good efficacy for
generalized tonic-clonic seizures, atypical absences
and tonic seizures, however caution should be taken
in interpreting these findings because of the lack of
control groups.