 The maintenance phase will be open labeled and consist of weekly treatments at the same parameters to which patients initially responded, for a total of 8 weeks. Maintenance treatment will then be further reduced to fortnightly treatments for 44 weeks. Patients will be evaluated clinically every 2 weeks. Should patients relapse i.e. a HAM-D score of 15 for 2 consecutive weeks, they will be offered active treatment only i.e. no sham treatment for up to six weeks at the same stimulus parameters to which they previously experienced a response. 