Stellate Ganglion Block for Major Depressive Disorder.

Inclusion Criteria:

1. 18 - 65 years of age
2. Major depressive disorder without psychotic symptoms according to DSM-5 criteria
3. Hamilton Depression Rating Scale (HAMD)>17
4. Current major depressive episode as confirmed by the Mini InternationalNeuropsychiatric Interview (MINI)
5. Failure of at least two trials of antidepressant therapy during the current episode
6. Capacity to provide informed consent

Exclusion Criteria:

1. Depression secondary to stroke, cancer or other severe medical illness
2. Major Depressive Episode in people with Bipolar Disorder.
3. Dementia
4. Post-Traumatic Stress Disorder (PTSD)
5. Acute suicidality defined as score ≥3 on HAMD item 3
6. Previous electroconvulsive therapy
7. Known history of intolerance of hypersensitivity to local anesthetic
8. Current substance abuse or dependence (except for caffeine or nicotine dependence)and/or recent history (last 12 months) of current alcohol abuse or dependence, asdefined in DSM-5 criteria
9. Unwilling to maintain current antidepressant regimen.
10. A clinical finding/condition that is unstable or that, in the opinion of theinvestigator(s) would negatively be affected by an SGB (e.g. movement disorder wherepatient is unable to lie still for injection or anatomical variants making an SGBimpractical).