Pain management after craniotomy

Fear of the side effects of analgesic drugs frequently leads to the under-treatment of post-craniotomy pain. Nevertheless, this pain continues to be commonly observed, is frequently severe, and, if unrelieved, may cause distress for the neurosurgical patient and serious complications for the operative brain. We review recent evidence-based data on pain therapy after intracranial surgery. Especially when performed at the end of surgery, local anaesthetic scalp infiltration provides adequate, short-term postoperative pain relief. Opioids, such as morphine or oxycodone, may be used in the early period after craniotomy. If titrated properly, opioids do not increase serious side effects as compared with codeine. The non-narcotics ketoprofen, tramadol, and paracetamol may be useful as supplemental, opioid-sparing drugs. There is a need for larger trials to delineate safety and efficacy of analgesic therapies with a focus on short- and long-term outcomes.

Introduction

Surgery and the associated tissue injury and inflammation is almost always associated with postoperative pain. Historically, postoperative pain has been under-treated and was often considered to be an undesirable but unavoidable complication of surgery. More recently, the recognition that poor pain control is associated with poor outcome and an increase in the incidence of many postoperative complications has led to clinicians taking a more proactive approach to prevent and treat postoperative pain. The Joint Commission on Accreditation of Healthcare Organizations in the United States has incorporated standards for postoperative pain management and, in many countries, adequate post-operative pain relief is considered a legal right.¹

Despite these advances in pain diagnosis and treatment, many clinicians consider intracranial surgery only to be associated with minimal patient discomfort. Indeed, a frequently cited retrospective chart review reported only minimal pain after brain surgery; however, this conclusion is based on only 90 minutes of postoperative observation of craniotomy patients who received more than 500 μg of intraoperative fentanyl.² To be sure, we now recognize that most intracranial procedures cause significant postoperative pain. Recent evidence indicates that post-craniotomy pain is reported as moderate to severe in up to 80% of patients and may persist for several days postoperatively, depending on the nature of tissue injury.*3, *4, 5, 6, *7, *8 Persistent headache remains an underestimated complication after craniotomy.*8, 9, 10 Despite these facts, experts and recent surveys increasingly emphasize that post-craniotomy pain continues to be poorly managed and under-treated.*3, 6, *8, 11, 12, 13

Recently, Gottschalk et al prospectively studied 187 patients who underwent major intracranial surgery.⁸ Nearly 70% of patients experienced severe pain (>4 on a 0–10 scale) during the first postoperative day and 48% on the second postoperative day. The authors found that despite continued complaints of severe pain, pain was treated only with high-dose acetaminophen and, in some cases, very small amounts of fentanyl. As eloquently noted in an accompanying editorial, “This seems to suggest that the treating physicians on the one hand believed that they should be able to get by with nonopiate analgesics (because craniotomy is not painful…), yet on the other hand realized that their patients suffered and therefore, fearing opiates, prescribed more and more of the nonopiate analgesic medication”.¹⁴

Three reasons may account for this situation. First, there are specific concerns that the side effects of potent analgesic drugs may cause miosis, respiratory depression, nausea, vomiting, and over-sedation. These adverse events may not only interfere with recovery from anaesthesia and postoperative neurological assessments, but may jeopardize the cerebral circulation and cerebral dynamics in patients with compromised intracranial compliance.¹⁵ As all opioids blunt the respiratory response to hypercarbia, there is concern that opioid-induced carbon dioxide retention will provoke increases in cerebral blood volume with the possible formation of cerebral edema with associated increases in intracranial pressure (ICP). Sympathetic activation may increase arterial and intracranial pressures and increase cerebral oxygen consumption. Serious complications, such as cerebral edema, ischemia, intracranial hemorrhage, or disruption of the delicate neurosurgical hemostasis may ensue.¹⁵ For example, a retrospective analysis of 11,214 craniotomy patients showed that perioperative systemic hypertension was associated with postoperative intracranial hemorrhage (ICH), which prolonged hospital stay and increased mortality.¹⁶ Additionally, there may be an increased risk for aspiration, as this population frequently has compromised pharyngeal and laryngeal reflexes.

Second, there is a lack of standardized, proactive protocols for the assessment and evaluation of post-craniotomy pain, pain therapy, and patient and caregiver education. Analgesic therapy and scope of pain after intracranial procedures is actually not included in several standard neurosurgical texts. This may in part relate to the fact that caregivers are faced with the difficulty of diagnosing pain and its severity in patients with aphasia, altered mental status, or cognitive impairment. Improved awareness of post-craniotomy pain may result in a more proactive approach to pain management.*7, *8, 14

Third, there is continuing controversy regarding the choice of the “best” anaesthetic regimen for intracranial surgery.17, 18, 19 Practice patterns using different combinations of anaesthetics and opioids have effects that extend variably into the postoperative period. This heterogenous approach to neuroanaesthesia precludes any uniform approach to post-craniotomy pain evaluation and treatment. Many studies fail to consider the potential differing effects of the drugs used intraoperatively. For example, remifentanil is frequently used as part of balanced anaesthetic during neurosurgical procedures. Remifentanil has several advantages when used in neuroanaesthesia including its quick onset and rapid metabolism. Whereas an anaesthetic that includes remifentanil may result in a more reliable emergence from anaesthesia and facilitate early neurologic assessment20, 21, 22, 23, the use of remifentanil has been associated with opioid tachyphylaxis and increased postoperative pain in several different surgical models.24, 25, 26 Nevertheless, significant postoperative pain has been reported in anaesthetics that did not utilize remifentanil. In fact, remifentanil was only utilized in 10.9% of the patients in the series reported by Gottschalk et al.⁸

In an effort to improve the postoperative care of patients undergoing craniotomy, we reviewed the evidence available on short- and long-term outcomes of analgesic therapy following brain surgery. We conclude with an attempt to formulate treatment options for post-craniotomy pain and provide a brief outlook on further research requirements.