Anxiety and Depression in a Psychiatrically Informed Pain Medicine Practice

Patients with chronic pain and head injury frequently have comorbid anxiety and depressive disorders, with depressive disorders appearing to be more predominant. A number of studies show that depressive spectrum illness develops in 40% to 80% of patients with chronic pain; in a majority of these cases, the mood disorder is caused by chronic pain.¹ Some studies have shown that over 50% of patients who are injured at work have comorbid posttraumatic stress disorder (PTSD) related to the initial work injury trauma (eg, a 30-foot fall that results in spinal trauma may also produce PTSD).² The same is true of patients with head injuries, in whom a high rate of PTSD has been documented.³

Association of chronic pain with depressive illness

There are many theories behind the link between pain and depressive disorders; some have evidentiary support.⁴ A psychological theory for pain-induced depression involves behavioral sequelae of injuries. Postinjury, patients are reduced to a far lower level of activity than they were previously accustomed to. They often can no longer complete simple activities of daily living or household chores, much less earn a living. Self-esteem is compromised, along with overall activity level. Sexual activity may be curtailed because of pain, and the patient may no longer feel like a complete person. This yields depressive, dysphoric mood reactivity that may become fixed.

Physiologically, there are biological changes associated with chronic pain that can produce depressive spectrum illness. Studies from the 1980s demonstrated that chronic pain is associated with a depletion of serotonin. In these studies, repletion via SSRI therapy improved pain tolerance and reduced pain levels.⁵ Although studies have called into question a simplistic model of low serotonin levels and pain, evidence has shown that serotonergic aberrations interact with noradrenergic aberrations, leading to the concept of dual-channel neurotransmitter deficits in chronic pain states.⁴ There is strong pharmacological research evidence that indirectly supports this concept. The evidence demonstrates that dual-channel antidepressants, such as duloxetine and venlafaxine, have specific efficacy for both depressive symptoms and the pain itself.⁶

As a result, organized pain medicine now recognizes the relevance of the biopsychosocial model of pain medicine.⁷ First proposed in the 1960s, this alternative to the traditional medical model addresses the social and psychological components of pain, whereas the medical model simply addresses the neurobiological basis for pain. Psychotherapeutic approaches are implemented to not only help address the biological basis for pain but also to improve overall functioning. This is in direct contrast to the biomedical/interventional model of pain management, where the focus is on injections and procedures. Clinics that adhere to the latter philosophy are typically staffed by anesthesiologists who often use nurse practitioners to prescribe narcotics and retain consulting psychologists to attend to the mental health needs of the patients.

Implementing the biopsychosocial approach

Our small subspecialty psychiatric medicine clinic practice focuses on patients who have sustained work-related injuries. The primary focus is to provide comprehensive pain and psychiatric evaluations, as well as treatment for patients with head, limb, and spine injuries; chronic pain; and comorbid psychiatric disorders. In our practice, depression and anxiety-spectrum disorders stemming from work injury are the most common comorbidities. We also evaluate patients for Axis II pathology that has been shown to complicate recovery from work injuries and can seriously impact pain management outcome.¹

To this end, our clinic employs a psychiatrist and a neurosurgeon who are board-certified in their respective fields. The psychiatrist performs psychiatric, neuropsychiatric, and physical examinations and provides pharmacotherapy for pain and comorbid psychiatric disorders. The neurosurgeon provides consultative evaluations, focusing on the identification of pain generators via physical and radiological examinations. A registered nurse serves as the general manager for the clinical and forensic service sections and provides intensive case management for the clinic's patients. A master's level nurse provides occupational and vocational assessments and life care planning services, and a licensed practical nurse provides general nursing care. A registered radiological technologist coordinates imaging studies and the computerized psychiatric assessment laboratory and doubles as an intake coordinator and medical assistant.

In adhering to the biopsychosocial model, the emphasis in our clinic is on the patient with pain-not the pain itself. We are as concerned with pain generators as we are with the psychological impact of pain on the patient, his or her life, and the impact on his or her family. In fact, we are more concerned with facilitating coping than with temporarily reducing pain. We do, however, perform some minor procedures, such as trigger point and occipital nerve root injections, and we have a strong emphasis on pain electrotherapy to minimize the need for narcotics.

Identifying psychiatric comorbidities

Many clinicians are convinced that pain cannot be effectively managed without also managing comorbid depression and anxiety-spectrum disorders and vice versa. In our practice, this is one of the basic tenets, if not the guiding principle, of treatment. In order to assess for such comorbid psychiatric conditions, we administer extensive psychiatric evaluations during a patient's initial visit, including such psychiatric measures as the Personality Assessment Inventory (PAI), the International Personality Disorders Examination (IPDE), and the Structured Clinical Interview for DSM disorders (SCID).

We have found that this model allows us to most reliably identify comorbid mood and anxiety disorders, as well as Axis II pathology. After the initial evaluation, patients are monitored at regular visits with ongoing computerized assessments via a modified version of the symptom questionnaire and various pain rating scales.⁸ Serial administration of these instruments and a patient's history allow us to monitor the patient's progress in terms of response to analgesics and psychopharmacotherapy, and allows for detection of deterioration, emergent stress reactivity, and suicidality.

Addictions, narcotics, and chronic pain

All clinics focusing on chronic pain and psychiatric comorbidity need to address the potential for substance abuse and addiction. Many of our patients have severe spinal pain disorders that require opiates and are referred to us while they are taking high doses of narcotic medications. We often begin weaning the patient from narcotic medications after the initial evaluation by adding opiate-sparing adjuvants. This is a common clinical strategy based on the concept that adjuvants can reduce the need for opiates.⁹Our guiding principle is to use the lowest narcotic dose that will effectively control pain and produce maintenance or improvement of functional status. This principle helps avoid the depressogenic effects of high-dose opiates as well as the potential for dependence and abuse.

Nevertheless, any patient requiring narcotics must be monitored for substance abuse and misuse. Periodic, random urine drug screens are an excellent way to monitor patients for whom controlled substances have been prescribed. If a urine drug screen fails to confirm the presence of prescribed agents or reveals illicit agents, then a quantitative blood assay is performed for confirmation. Similarly useful is the Aberrant Drug Behavior Scale of the Pain Assessment and Documentation Tool (PADT), which relies on input both from staff and the patient. Cases of misuse and abuse are referred to our advisory board, as needed, for disposition.

Generally, patients with substance abuse disorders are treated in our clinic without the use of scheduled drugs (eg, opiates) to avoid triggering a relapse. Instead, their treatment focuses on neuromodulation agents (eg, anticonvulsants), antispasmodics, various injections (eg, trigger point injections), and electrotherapy (eg, percutaneous neuromodulation therapy).⁹

There are also several types of patients that are systematically excluded from acceptance into our practice, because our experience and some research have demonstrated poor pain management outcomes with them.¹ These groups of patients include those with severe, active cluster B personality disorders who are untreated, patients with diagnosed somatization disorder (particularly those without clear anatomic pain generators), and those with documented conversion disorders (who lack anatomic pain generators). Such patients, we feel, are best referred to general psychiatrists in the community for management of core psychiatric disorders.

Forensic and administrative challenges in psychiatric pain medicine

Patients with chronic pain and psychiatric comorbidities are more complicated and, thus, inherently more challenging than patients with either problem alone. There are also administrative challenges, which include dealing with workers' compensation insurance carriers and their adjusters, the majority of whom lack a medical background. Fortunately, some adjusters are open to being educated about chronic pain and psychiatric problems, and our staff spends significant time educating them about these issues. Frequently, educating the adjuster about the biopsychosocial model of pain becomes extremely important. When primitive attitudes are overcome through education about the patient's condition and related treatments and options, adjusters often take on a collaborative role and work to ensure the best outcome for the patient.

Case Vignette

Mr X is a 62-year-old former law enforcement official from a major city. During his career, he sustained injuries to his spine that required multiple fusions. He also incurred an inoperable fracture to the thoracic spine. He presented to the clinic in severe pain despite prescriptions for narcotic analgesics, was severely depressed with paranoid ideation, and seldom left his bed.

We aggressively treated his symptoms of psychotic depression with dual-channel antidepressant therapy (SSRI and a serotonin norepinephrine reuptake inhibitor) and we prescribed a selective D₂ blocker. We controlled the pain by progressively weaning him from the long-acting opiates. Once his depressive illness was in remission and his pain was under control, we began a series of trigger point injections and percutaneous neuromodulation therapy designed to minimize the need for opiates (which he strongly desired). With the help of the insurance adjuster, we were also able to get him a hot tub for hydrotherapy for muscle spasms.

The patient still has pain, especially during weather changes, but he only takes opiates at low doses on an occasional pain-rescue basis. He actively pursues hobbies, has an active life with his wife and grandchildren, and manages a small ranch as a hobby.

Some adjusters have extreme biases against patients with pain, and view them as malingerers, even those with catastrophic injuries. Worse, some adjusters have even more malignant biases toward patients with psychiatric illness, viewing them as either "crazy," malingering, or just "weak." In these cases, educating the adjuster about the biopsychosocial model of pain becomes extremely important. Unfortunately, we are not always able to change an adjuster's attitude and sometimes the patient's attorney has to intervene to ensure that needed medical care can be provided as required by law.

Case Vignette

Mr Z is a 58-year-old Vietnam veteran who returned from the war relatively unscathed. He began work in a local factory where he was involved in a severe chemical explosion. In the accident, he was thrown over 50 feet and sustained burns over 60% of his body; several of his coworkers were killed. PTSD and spinal pain syndrome developed. He began having nightmares, ran through his house while asleep and at one point sustained further injury by running through a glass door. Afterward, he began sleeping outdoors in a lawn chair or would tie himself to his bed to prevent sleepwalking. He was treated for PTSD by multiple psychiatrists, which included an inpatient hospitalization with no improvement.

On referral to our clinic, we began simultaneous treatment of PTSD, sleep dysfunction, and chronic pain. He was found to be a rapid metabolizer on the cytochrome P-450 2D6 system (based on laboratory and clinical findings, along with medication blood levels) and required what appeared to be large doses of some medications. He was referred for psychotherapy with a psychology associate, and eventually he was stabilized on a regimen of anxiolytics, an SSRI, long-acting opiates for pain, and an anti-insomnia agent.

The PTSD has been in full remission for about 12 months. The patient sleeps 7 to 8 uninterrupted hours per night without nightmares and actively runs his home-based business. He recently began to exhibit deterioration, because his insurance adjuster is attempting to force him to "settle his medicals" (as a cost containment measure); and he is required to travel across the state for a medical examination with an insurance company-approved physiatrist who has no training in psychiatric disorders. His psychologist and our staff are extremely concerned about this conflict, and we are currently working with his attorney to intervene on the patient's behalf.

Conclusions

More often than not, chronic pain is accompanied by anxiety- and depressive-spectrum disorders. By treating pain and psychiatric disorders simultaneously, we are able to maximize outcomes. Similarly, a biopsychosocial model of pain that optimizes patient-centered care can improve outcomes. Our group's philosophy of pain medicine practice can be articulated by the 5 principles summarized in the Table.

Although the management of psychiatric disorders and pain in the work injury setting can be challenging, the rewards of watching patients return to happy, healthy, and productive lives are significant. We encourage psychiatrists to make themselves available as consultants to the pain clinics in their communities and to work cooperatively with pain physicians. We likewise encourage interventional pain clinics to use the services of psychiatrists. Without doubt, patients will benefit from such collaboration.

References:

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