Multimodal analgesia in neurosurgery: a narrative review

Pain following brain surgery can compromise the result of surgery. Several pharmacological interventions have been used to prevent postoperative pain in adults undergoing brain surgery. Pain following craniotomy is considered to be moderate to severe during the first two post-operative days. Opioids have been historically the mainstay and are the current prominent strategy for pain treatment. They produce analgesia but may alter respiratory, cardiovascular, gastrointestinal, and neuroendocrine functions. All these side effects may affect the normal postoperative course of craniotomy by affecting neurological function and increasing intracranial pressure. Therefore, their use in neurosurgery is limited, and opioids are used in case of strict necessity or as rescue medication. In addition to opioids, drugs with differing mechanisms of actions target pain pathways, resulting in additive and/or synergistic effects. Some of these agents include acetaminophen/non-steroidal anti-inflammatory drugs (NSAIDs), alpha-2 agonists, NMDA receptor antagonists, gabapentinoids, and local anesthesia techniques. Multimodal analgesia should be a balance between adequate analgesia and less drug-induced sedation, respiratory depression, hypercapnia, nausea, and vomiting, which may increase intracranial pressure. Non-opioid analgesics can be an useful pharmacological alternative in multimodal regimes to manage post-craniotomy pain. This narrative review aims to outline the current clinical evidence of multimodal analgesia for post craniotomy pain control.