Chronic pain is defined as 'an unpleasant sensory and emotional experience associated with actual or potential tissues damage, or described in terms of such damage". It is estimated that 1 in 5 Canadians experience chronic pain "Chronic pain is associated with the worst quality of life compared with other chronic diseases such as chronic lung or heart disease". Many of these problems are confined to a specific anatomic structure, and can be diagnosed and treated by injections, physical therapy, surgery, etc. Nonetheless, other individuals experience a more generalized pain. This condition has also resulted I depressed mood, bad relations with other people, sleep disturbances and poor quality of life.

The condition is very difficult to manage, and multiple methods have been recommended. Therapeutic intravenous infusion may be considered as one of these methods. Patients come for infusions of non-opioid medications under medical supervision and in a scheduled fashion. Two most commonly used mediation are lidocaine and ketamine.

Even though it is common to use multiple medications with complementary mechanisms of action to treat pain a combined lidocaine-ketamine infusion has never been studied Therefore, the purpose of this research study is to determine whether mixture of two medications (ketamine and lidocaine) infused intravenously 1 time per month for 6 months results in reduction of pain unpleasantness.

Inclusion Criteria:

• Age 18-90
• Pain duration: > 3 months
• Multifocal and/or non-dermatomal neuropathic pain per Pain Diagram
• Failed medical management with at least 2 neuromodulation agents (e.g., gabapentinoids, antidepressants)
• Neuropathic component (>15 points on S-LANSS)

Exclusion Criteria:

• Non-English speakers
• Refusal to sign informed consent
• Body weight > 100 kg
• Allergies to ketamine and/or lidocaine
• Known contraindications to ketamine use which include poorly controlled systemic illnesses: arterial hypertension, hyperthyroidism, ischemic heart disease, heart failure, psychiatric comorbidity (e.g., history of psychosis, schizophrenia, dissociative state).
• Known contraindication to lidocaine use which include current symptomatic or clinically significant brady- or tachyarrhythmia, systolic blood pressure <90 or >180 mmHg.
• Scheduled interventions targeting neuropathic pain: epidural injections, peripheral nerve blocks, Bier block, radiofrequency of dorsal root ganglia and peripheral nerves, additional lidocaine or ketamine infusions
• Newly added analgesic or neuromodulating medications, or recently performed interventions including lidocaine infusions (in the previous 3 months), or previous lidocaine/ketamine infusion in the previous 360 days. -Acute intoxication or active illegal substance abuse (excluding marijuana)