Pain

Patients with pain disorders pose many clinical challenges for the attending physician. Even experienced clinicians occasionally arrive at the point where diagnostic, work-up, treatment, or prognostic thinking becomes blocked. Pain teaches the reader to recognize and appropriately treat a variety of pain disorders using a case study format. Divided into three section, chronic pain conditions, chronic pain and related disorders, and treatment overview, and derived from consultation requests from providers in medical practice, the cases are written in a format that encourages the reader to formulate a differential diagnosis and treatment plan for a variety of pain problems. Succinct in its presentation and logical in its layout, Pain is the perfect resource for the busy practitioner on the go. * Each case is presented as if the reader were learning about the case for the first time in the hallway or office * Key clinical take-home points are listed at the end of each chapter for easy reference * Tables and figures are used whenever possible, and all chapters include references for further reading Tabitha A. Washington , Associate Pain Fellowship Program Director, Pain Medicine, Professor of Anesthesiology, Department of Anesthesiology, Dartmouth-Hitchcock Medical Center, Dartmouth Medical School, Khalilah M. Brown , Fellow Pain Medicine, Department of Anesthesiology, Dartmouth-Hitchcock Medical Center, Dartmouth Medical School, and Gilbert J. Fanciullo , Director, Section of Pain Medicine, Professor of Anesthesiology, Department of Anesthesiology, Dartmouth-Hitchcock Medical Center, Dartmouth Medical School CONTENTS SECTION I CHRONIC PAIN CONDITIONS 1. Complex Regional Pain Syndrome Commonly over diagnosed, CRPS has little especial association with the Autonomic Nervous System, does not involve Dystrophy, and has no known Reflex associated with it. Type 1 is the classical Reflex Sympathetic Dystrophy differing from Type 2- Causalgia, only in that Type 2 involves injury to a major nerve. 2. Peripheral Neuropathy The debilitating pain of peripheral neuropathy can be difficult to treat and relies on pain management and treatment of the underlying pathology. This chapter reviews the causes, sign and symptoms, diagnostic criteria and treatment options available for these patients. 3. Post-Herpetic Neuralgia Post-herpetic neuralgia is a devastating and painful consequence of shingles (herpes zoster) and is most common in the elderly and the immunocompromised. Medications are the mainstay of treatment, however caution should be used in the elderly secondary to side effects. 4. Post-Stroke Central Pain Often thought only in association with thalamic pain syndrome following infarct to the thalamus, pain following stroke may occur with any setting of stroke affecting nociceptive fibers at any level. Neuropathic or central pain can occur in up to 8% of patients after a stroke. Medical treatment usually begins with a trial of Lamotrigine and a second-line drug may be added. For severe, refractory cases, repetitive transcranial magnetic stimulation (rTMS) may be offered. 5. Multiple Sclerosis Related Pain Multiple sclerosis (MS) is usually associated with a loss of sensation; however, since the late 1800s, physicians have recognized that pain is often associated with multiple sclerosis and can at times be the heralding symptom. Pain can occur in 29-86% of MS patients an can include neuropathic pain, dysesthetic pain and trigeminal neuralgia, as well as somatic pain mostly originating from back pain and painful spasms. Medication, physical therapy, behavioral therapy, occupational therapy, interventional procedures, baclofen pump placements, and surgical interventions have been employed. 6. Radiculopathy Probably the most common cause of neuropathic pain, lumbar and cervical radiculopathy are frequently encountered clinical entities while thoracic is more rare. These syndromes may involve an anatomical abnormality and can be gratifying to both diagnose and treat, but a nonanatomical abnormality syndrome is equally as common and presents more of a diagnostic and therapeutic dilemma or even conundrum. 7. Brachial Plexus Avulsion Injury Brachial plexus injuries are most commonly due to trauma, of which, motor cycle accidents are the most common. Men are most frequently affected. Other causes can include; penetrating or sports related injuries, falls, work related accidents, radiation therapy and iatrogenic causes (ie, first rib resection, shoulder surgery, interventional radiology). The most common mechanism of injury is a traction injury due to forceful separation of the neck from the shoulder. Persistent brachial plexus pain is often treated in a fashion similar to neuropathic pain. 8. Superficial Radial Nerve Injury This small sensory nerve can be a cause of excruciating pain when injured iatrogenically. Diagnosis can be confusing and treatment a challenge. 9. Post-Thoracotomy Pain Syndrome (Acute and Chronic Pain) Persistent post-thoracotomy pain syndrome (PTPS) is one of the most prevalent sources of chronic post-operative pain. Up to 20-70% of patients may complain of symptoms consistent with post-thoracotomy pain. Targeting the points before, during, and after surgery that could decrease the risk of PTPS has been understudied and there is no clear evidence for any specific recommendations. That being said, recommendations and standard of care include a multimodal analgesic approach during surgery and perioperatively with nonopioid and local anesthesia. Treatment of chronic PTPS can include medical therapy, interventional therapy and in those with refractory disease, spinal cord stimulation. 10. Dental Pain Branches of the Trigeminal Nerve are not infrequently injured during routine dental procedures and can produce symptoms similar to Tic Douloureux. Proper anatomical localization and an understanding of the mechanism of injury can be important considerations in selecting treatment approaches or determining prognosis. 11. Trigeminal Neuralgia and Atypical Facial Pain Trigeminal neuralgia is a debilitating disease that affects a subset of patients. This chapter focuses on the epidemiology, diagnostic criteria and management of patients. Special considerations to the elderly population who are at higher risk of developing side effects from treatment. 12. Phantom Limb Pain Phantom pain is described as pain or dysesthesia that is caused by interruption or discontinuation of sensory nerve impulses by destroying or injuring the sensory nerve fibers after amputation or deafferentation. The usual cause of pain is due to trauma or surgical manipulation. The incidence of phantom limb pain varies across studies and is on the order of 2-80%; however, the average appears to be between 40-70%. Medical therapy should be tried initially and should not be considered a failure until narcotic therapy has been trialed. Surgical therapy including spinal cord stimulator placement and DREZ lesions should be reserved for refractory cases. 13. Spinal Cord Injury Pain Injury to the spinal cord can occur via trauma, infection, ischemia, toxicity, tumor, radiation, disease or other causes. The pattern of pain may still be changing years or even decades after injury. The level of pain and disability may be very high and effective treatment options may be illusory. 14. Ramsey Hunt Syndrome (Geniculate Neuralgia) Ramsay- Hunt Syndrome is a rare entity that was first described in the early 1907 by James Ramsay Hunt. There are three Ramsay-Hunt Syndromes that vary dramatically from one another with the only similarity being that they were described by the same person. In this article, we will discuss Ramsay Hunt Syndrome Type II, commonly known as herpes zoster oticus and is accompanied by a peripheral facial palsy. It is the second most common cause of atraumatic peripheral facial nerve palsy. 15. Supraorbital Neuralgia Supraorbital neuralgia is pain in the distribution of the supraorbital nerve that is often caused by a provoking stimulus, such as goggles or helmets. However, other causes should be excluded with history, physical exam and neuroimaging studies. 16. Glossopharngeal Neuralgia Glossopharyngeal neuralgia (ninth cranial nerve) presents with severe, brief, stabbing, recurrent pain in the back of the throat and tongue, the tonsils, and part of the ear. Secondary causes must be excluded and treatment focuses on polypharmacy. 17. Arachnoiditis The debilitating pain of arachnoiditis can be difficult to treat and progressive. This chapter reviews the causes, sign and symptoms, diagnostic criteria and treatment options available for these patients. 18. Occipital Neuralgia Occipital neuralgia is defined by the International Headache Society (IHS) as paroxysmal shooting or stabbing pain in the dermatomes of the nervus occipitalis major or nervus occipitalis minor. The pain in occipital neuralgia is characterized as burning, lancenating pain that, like migraine, is usually unilateral with radiation to the frontal, orbital and periorbital regions. Treatment flow guidelines start with; history and physical exam, followed by performing a test block, then considering more long-term blocks with anesthetic and corticosteroid or with radiofrequency ablation of the occipital nerve. 19. Cancer Related Pain With over 10 million cancer survivors in the United States and the incidence of cancer treatment related pain syndromes soaring higher each year, the tumor itself is less often the cause of pain than is the treatment. Knowledge of injuries that can occur due to chemotherapy, surgery and radiation therapy are crucial in trying to understand and manage cancer pain. 20. Mononeuropathy Mononeuropathies are a not uncommon source of pain, of which, one of the most notable is post-herpetic neuralgia, which is covered in its own section of this book. Other notable painful mononeuropathies include, diabetic mononeuropathy and amyotrophy, mononeuropathy multiplex, entrapment neuropathies, and mononeuropathies due to peripheral nerve tumors. SECTION II CHRONIC PAIN AND RELATED DISORDERS 21. Chronic Pain and Depression In treating patients with chronic pain with a co-morbidity of depression, the focus is on a multimodal approach to their treatment. This chapter reviews the pathophysiology and treatment strategies for patients suffering from chronic pain and depression. 22. Chronic Pain and Addictive Disorder The intersection of pain and addiction to opioids is a problem that has defied understanding and solution since 3000 BCE. While addictive disorders do not make treatment with opioids impossible, they certainly make it more dangerous for our patients and society not to mention the emotional and temporal strain they may place on providers. 23. Chronic Pain and Other Psychiatric Condition Chronic pain patients often present with a co-morbid psychiatric abnormality, of which the anxiety disorders and depression are the most common. Concomittant treatment of the psychiatric disorder not only improves emotional health, but can also improve pain scores, functional improvement, and overall sense of well-being. Treatment with anti-depressants and with psychiatric therapy is the mainstay of treatment. 24. The Difficult Chronic Pain Patient The prevalence of Cluster B personality disorders in chronic pain patients may exceed the prevalence in clients seen by parole officers. These patients can be labor intensive, produce feelings of incompetence, can be unfulfilling to care for and may in fact at times be dangerous. SECTION III TREATMENT OVERVIEW 25. Antidepressants Antidepressants are often used for the treatment of chronic pain. This chapter will address the efficacy and indications for their use, as well as a discussion of the classes, adverse effects and their use in clinical practice. 26. Anticonvulsants Anticonvulsants are often used for the treatment of chronic pain. This chapter will address the mechanism of action and efficacy of these agents. In addition, indications for their use, adverse effects and their use in clinical practice. 27. Opioids With limited evidence documenting efficacy and with serious side-effects that are becoming more apparent every year, the controversy surrounding the use of opioids for non-terminal chronic pain has never been so strident. Risk assessment and monitoring are essential in order to ensure both safety for our patients and society and ensuring our patients access to these drugs which can in select patients be so useful. 28. Other Adjuvant Drugs Adjuvant drugs are often used for the treatment of chronic pain. This chapter will address commonly used agents and their use in clinical practice. 29. Spinal Cord and Peripheral Nerve Stimulation Spinal cord and peripheral nerve stimulation is being used more frequently in chronic pain conditions. This chapter discusses the pathophysiology, indications, surgical procedure, risks and outcomes for patients who utilize these modalities for pain control. 30. Neurosurgical Procedures for Pain Neurosurgical techniques have long been used for the treatment of intractable pain. They have been considered the most logical treatment choice for pain in that they would cause a blockade of a patient's pain pathways and thus prevent the transmission of pain signals to the cortex. Over time, neurosurgical techniques have become more sophisticated and there are now multiple modalities being used to treat similar pain states. When determining whether or not neurosurgical intervention is warranted for a patient with intractable pain, many authors have offered that clinicians can pose themselves the question as to the nature of their patient's pain- intractability and quality of pain. 31. Marijuana Fifteen States in the US and many countries in the world now permit the use of marijuana as a treatment for chronic pain. There is an expanding body of knowledge endorsing the efficacy of the drug but limited and disputed data surrounding safety. Patients will be asking their providers to help them make decisions regarding the use of marijuana for chronic pain and they must understand the issues.