Understanding How Methadone Treatment During Surgery Affects Pain Levels and the Need for Pain Medications After Surgery

Inclusion Criteria: * Adult patients (between 18-75 years of age) scheduled for extradural spine surgery with instrumentation (greater than or equal to two levels and including minimally invasive) of expected duration ≥ 2 hours * Postoperative hospital stay expected to be ≥ 2 nights at the time of consent Exclusion Criteria: * Use of methadone currently or within the previous 6 weeks * Drug misuse history (e.g., ketamine, cocaine, heroin, amphetamine, methamphetamine, MDMA, phencyclidine, lysergic acid, mescaline, psilocybin). * Current use of opioid antagonist/partial antagonist (i.e. buprenorphine). * Current or past diagnosis of a Major Psychiatric disorder (such as Schizophrenia, dementia, delirium). * Patients with a BMI ≥ 36 kg/m2 * 2nd or 3rd degree heart block as assessed by preoperative EKG. * QTc \> 450 msec on preoperative EKG. * Documentation of congestive heart failure and/or ejection fraction \< 30% if recorded in the Pre-Operative Record. * Contraindication to use of any analgesic medications listed in the ERAS pathways (acetaminophen, gabapentin, celecoxib, IV opioids). * Any known hypersensitivity to methadone. * Pregnant or breastfeeding. * Abnormal liver function tests as related to the MSK guidelines for use of IV acetaminophen: ALT greater than 2 x Upper Limit of Normal (\> 75 U/L) * Serum Creatinine \> 1.5 mg/dl * Instrumented spine cases of less than 2 levels * All non-instrumented spine cases * All intradural tumor resections * All "take backs" that occur within 72 hours of surgery (wound revisions, hematomas, etc.)