The use of electroconvulsive therapy in Quebec - INESSS

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The vast majority of these studies examined
damage to the verbal memory, to which the left hemisphere
of the brain contributes. In this respect, right
unilateral electrode placement greatly decreases
these effects and is as effective when used with electrical
charges several times greater than the seizure
threshold [McCall et al., 2000; Sackeim et al.,
2000a]. Few studies have examined the unilateral
right application of ECT on the visuospatial memory,
which depends almost exclusively on the right hemisphere
of the brain. Each of two 15-patient studies
demonstrated some damage to the visiospatial
memory, which disappeared entirely within a few
days [Hasse-Sander et al., 1998] or a few weeks
[McCabe, 1995] after the last ECT treatment session.
Taking into account the low patient numbers in these
two studies, the possibility of permanent effects on
this form of memory should be a top priority of future
research.
The study of ECT’s side effects is complicated
by damage to the cognitive functions by the depression
itself. Concerning the effects of ECT treatment on
cognitive functions other than those of memory, a
systematic review of the various studies published
between 1975 and 1993 concluded that
“with early methods of ECT administration (sine
wave, high dose), these effects are larger than
those of depression. They are less pronounced,
and usually do not exceed the effects of depression,
when modern methods of ECT administration
(brief pulse, moderate or low dose) are
used. […] The results of this review argue that
clinicians should take the non-memory cognitive
effects of ECT into account, and patients should
be informed of their existence before they sign
consent for ECT.” [Calev et al., 1995, p. 505]
Certain ECT practitioners continue ECT after
the end of the initial treatment, with less frequent
treatment sessions (between one and two per month).
THE USE OF ELECTROCONVULSIVE THERAPY IN QUÉBEC
This form of treatment is known as maintenance ECT.
The effects of this treatment mode on the cognitive
functions have seldom been studied [Rabheru and
Persad, 1997]. In a case description, a patient
presented a state of dementia after two years of
maintenance therapy, but her condition gradually
improved over a nine-month period after the treatment
was stopped [Regestein et al., 1975].
The anaesthesia itself may affect the cognitive
functions in the short, medium and long term. In
elderly patients particularly, anaesthesia may cause
cognitive dysfunctions, affecting visual and auditory
attention as well as various forms of memory.
Together, these cognitive disabilities are called “postoperative
cognitive dysfunction,” or POCD. Although
the aetiology of this dysfunction is not yet known, it
may be linked to the neurotransmitters in the cholinergic
system [Ancelin et al., 2000]. A study on the
incidence of POCD in a population of individuals 60
years of age or older who underwent major noncardiac
surgical interventions established the incidence
of POCD at 9.9% after three months and at
approximately 1% one to two years after the intervention
[Abildstrom et al., 2000]. We do not know
the incidence of POCD in younger patients or in those
who have undergone minor surgery [Rasmussen,
1999].
In the absence of accurate knowledge on
the impacts of short-term anaesthesia such as that
used for an ECT treatment, we cannot distinguish the
impacts of the anaesthesia from those of the electrical
stimulation itself. In a randomized, double-blind
study of 53 patients treated by ECT, no difference
was noted between the two most commonly used
anaesthetics in ECT, namely propofol and methohexital,
concerning their effects on anterograde
amnesia [Martensson et al., 1994]. However, a
high dosage of methohexital may increase ECT-