A Comparison Between Neurostimulation and Loss of Resistance for Cervical Paravertebral Blocks

Inclusion Criteria are: * age between 18 and 70 years * American Society of Anesthesiologists classification 1-3 * body mass index between 20 and 28 Exclusion criteria are: * adults who are unable to give their own consent * pre-existing obstructive or restrictive lung disease (assessed by history and physical examination) * pre-existing neuropathy (assessed by history and physical examination) * coagulopathy (assessed by history and physical examination and, if deemed clinically necessary, by blood work up ie platelets≤ 100, International Normalized Ratio≥ 1.4 or prothrombin time ≥ 50) * renal failure (assessed by history and physical examination and, if deemed clinically necessary, by blood work up ie creatinine≥ 100) * hepatic failure (assessed by history and physical examination and, if deemed clinically necessary, by blood work up ie transaminases≥ 100) * allergy to local anesthetic agents (LA) * pregnancy * prior cervical spine surgery