<prompt> An anesthesia resident was giving spinal anesthesia when the patient had sudden aphonia and loss of consciousness. What could have happened?Total spinalPaial spinalVaso vagal attackIntra vascular injection  <response>: Any condition leading to decreased venous return or any affective mechanism such as pain or fear can trigger a circulatory change leading to vaso vagal attack. This in response brings about a parasymapthetic activation and sympathetic inhibition leading to hypotension and bradycardia. It is accompanied by nausea, pallor, sweating, giddiness and also loss of consciousness. Such a vaso-vagal syncope in the clinical scenario given in the question above was brought about during the procedure of spinal anesthesia was being carried out. Ref: British Journal of Anaesthesia 2001, 86, 859 - 868; Syncope: An Evidence-Based Approach By Michele Brignole, David G. Benditt, Page 160 Essentials of Regional Anesthesia By Alan David Kaye, Richard D. Urman, Nalini Vadivelu, Page 282. 