The Pain of Neurosurgical Residency
Neurosurgery residents deal with both acute surgical pain and a variety of chronic pain syndromes ranging from lower back pain and failed back surgery syndrome to complex regional pain syndrome and trigeminal neuralgia. As the surgical management of acute and chronic pain has become a more prominent component of neurosurgical practice, it is imperative that resident physicians not only have exposure to, but also benefit from, a well-defined “pain curriculum.” This can be accomplished through education on pharmaceutical management, participation in a wide variety of pain procedures and involvement in research to review the outcomes of such interventions.
What’s the Best Way?
The opiate epidemic in the U.S. has led to over 15,000 deaths involving prescription opioids, and more than 2 million Americans are addicted to, or abuse, prescription opioids. Beginning in the 1990s, a nationwide push was made to not only treat pain but to cure it. The rate of opiate prescriptions skyrocketed and fueled, if not directly led to, our current crisis. Postoperative pain control can be notoriously difficult in the neurosurgical setting and often leads to inadequate analgesia. In our sickest patients, the disease process often leads to the patient’s inability to communicate. A balance between adequate analgesia and a non-depressed neurological exam must be struck. The simplest approach for a resident, which is often the one that patients request, is to provide ever increasing doses of opioids. However, the use of multimodal pain management strategies should be routinely implemented to best manage postoperative pain.
Therapies should target different points on the pain pathway. Corticosteroids for acute radiculopathy and neuropathic pain exacerbations can be exceptionally helpful. Other options include, intravenous acetaminophen as an adjuvant to opioids; ketorolac, an NSAID that inhibits prostaglandin synthesis (although there is still debate as to whether it is associated with an increased risk of post-operative bleeding); gabapentin and pregabalin, which target calcium receptors; and in patients with refractory pain, ketamine. Interestingly, some of the serotonin and serotonin-norepinephrine reuptake inhibitors (SSRIs and SNRIs) can be used inpatient as the analgesia affect may occur in just 3-5 days, as opposed to gabapentin and pregabalin which may take 3-4 weeks. Other antidepressants, such as MAO inhibitors and tricyclics, work similarly. These medications can be augmented with epidural steroid injections, physical therapy and biofeedback techniques while the patient is inpatient.
Recently, discharge medications, specifically opioid prescriptions, have become a topic of discussion and study. Research conducted at Dartmouth demonstrated significant variation in the number of opioids prescribed for five outpatient procedures. It went further and showed that on average, less than 30 percent of those pills were used by the patient. Other studies have found that these excess pills are often not stored securely or properly disposed of, leading to the intentional or accidental diversion of these highly addictive and abused medications.
New York State assists residents and all providers by providing the Internet System for Tracking Over-Prescribing (iSTOP), a prescription monitoring program, which allows practitioners to review all Schedule II, III and IV controlled substances that a patient has been prescribed by all providers. If patients are on chronic opioids managed by our practice, pain contracts are essential. The agreement, unique to each doctor-patient relationship, sets out the goals and conditions for treatment and opioid prescriptions. It typically includes goals of care, conditions of the prescription and grounds for termination. Urine drug screens are used to supplement the contract. Most pain contracts include a clause prohibiting the prescription of narcotics from any other physician.
Surgical Treatment of Pain
Neurosurgery is one of the few specialties that offers surgical treatment of chronic pain. Neuromodulation, a rapidly advancing subfield of neurosurgery, is embracing new technology to treat chronic pain. In our practice, spinal cord stimulation (SCS) is a common procedure for junior residents and is an ideal case to learn basics of surgical skills and spinal cord neuroanatomy/neurophysiology. While the precise mechanism of SCS is still unknown, its development was based on the gate control theory of pain: the idea that a non-painful stimulation activates non-nociceptive nerve fibers which inhibit the firing of nociceptive fibers.
Subsequent studies have also demonstrated that SCS promotes gamma-aminobutyric acid (GABA) activation and decreases the excitation of dorsal horn cells. Given the importance and difficulty of patient selection, prior to permanent implantation of the stimulator, patients typically undergo a week-long trial using percutaneously placed electrodes. Validated pain and function scales, such as the Visual Analog Scale, the McGill Pain Questionnaire and Oswestry Disability Index are essential. They are used to evaluate pre- and postoperative pain, as metrics aiding in patient selection and with research studies. A successful SCS trial is typically considered greater than 50 percent reduction in pain. Neuropsychological testing and a goals of care discussion are also mandatory preoperatively. The permanent surgical placement procedure typically involves a one level laminectomy and the placement of the paddle electrode in the midline of the dorsal epidural space under direct fluoroscopy. Percutaneous procedures are another option.
Given the volume of SCS at our institution, both residents and medical students have excellent opportunities to be involved in chronic pain research. Projects have ranged from prospective studies demonstrating cervical SCS efficacy to those looking at factors predisposing patients to SCS treatment success and failure. Other neuromodulatory procedures reviewed include the implantation of intrathecal pain pumps, motor cortex stimulation for trigeminal neuropathic pain and peripheral nerve stimulation for trigeminal neuralgia and complex regional pain syndrome.
Ablative procedures represent another category of neurosurgical procedures for the treatment of pain. Although these procedures have been largely replaced by stimulatory neuromodulation, they are still practiced. Cordotomies involve the destruction of the lateral spinothalamic tract of the spinal cord which carries pain and temperature information. Today, these are typically done using radiofrequency ablation under local anesthesia with CT guidance. Midline myelotomies are used to treat intractable visceral pain, typically in patients with abdominal cancers, and result in the destruction of the dorsal columns. Glycerol or radiofrequency rhizotomies are performed for the treatment of trigeminal neuralgia. Recently, our practice has begun studying the use of ablative high-intensity ultrasound to treat neuropathic pain non-invasively in animal models.
Neurosurgery residents are exposed to a wide variety of treatment modalities for acute and chronic pain during their training. Further education for residents about opioid prescribing practices and non-opiate treatment modalities is vital. Having exposure to the newest pain treatments and the ablative procedures with which neurosurgeons founded the field of pain management provides a unique perspective to us all.
2. Hill, M. V., Mcmahon, M. L., Stucke, R. S., & Barth, R. J. (2017). Wide Variation and Excessive Dosage of Opioid Prescriptions for Common General Surgical Procedures. Annals of Surgery, 265(4), 709-714.
4. Rudd, R. A., Seth, P., David, F., & Scholl, L. (2016). Increases in Drug and Opioid-Involved Overdose Deaths — United States, 2010–2015. MMWR. Morbidity and Mortality Weekly Report, 65(5051), 1445-1452.
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