In 1934 convulsie therapy was used for the
first time in psychiatry. In 1938 electricity was shown to be useful in treating
psychiatric disorders (Seshadri et al. 2011). Nowadays Electroconvulsive Therapy (ECT)
is a widely used treatment in the field of Psychiatry for disorders like
Schilzofrenia, Bipolar disorder and Depression. In ECT electrodes
are placed on the cranium. This can be done bilaterally, but also unilaterally.
The current spreads over the entire brain. Many neurons are affected. The mean current
density in unilateral ECT is less than in bilateral ECT. The density in unilateral
ECT is 2/3 of the density in bilateral ECT. Unilateral ECT does however have
less adverse effects. During ECT different neurotransmitter systems may be involved.
Mono-aminergic systems such as serotonin (5-hydroxyrtryptamine) is thought to
be involved in treating Depression with ECT (Shihara et al. 1999).
In 80%-90% of patients with major depression
ECT has been shown effective. During ECT a minimum stimulus intensity is used,
called seizure threshold. This is used during ECT to evoke a seizure in the
patient. The seizure threshold is dependent on different factors. It depends on
age and is higher in men. An optimal stimulus is important, as cognitive side
effects should be limited. Implications include memory loss, headache and difficulty
conentrating. If on the other hand the stimulus is insufficient, the treatment’s
efficacy decreases. To determine the seizure threshold for a patient, empirical
titration is performed. Subconvulsive intensities are used. This is done during
the first treatment. A fixed dose higher that the seizure threshold is noted in
subsequent sessions. Seizure threshold can also be measured via the preselected
dosage method. In this method a suprathreshold dose is chosen on the basis of
factors such as age, seks and placement of electrodes. This is less accurate
than the emperical titration method, but no subconvulsive stimulation is needed
in this method. During an evoked seizure, contractions of facial muscle, jaw
and plantar extension occur for 10-20 seconds. After that the clonic phase occurs.
An effective seizure lasts at least 20-25 seconds (Elitan et al. 2006).
In the practice of ECT most changes and
developments have been driven to reduce the adverse effects and less by the
need to make it more efficacious. Current aim is to use a threshold that just
evokes a seizure, but is not too high, in order to reduce the cognitive side
effects. A seizure threshold that just about produces a generalised
tonic-clonic seizure may however not ensure therapeutic potency. This Systematic
Review aims to determine a seizure threshold to maximise remission in patients
with Depression. This study hopes to contribute to improve the efficacy of ECT,
create a better insight in the medical use of ECT and improve remission in
patients suffering from Depression.