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(Drug information on 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.