The possibility of drug addiction as a motivation for visiting the physician and reporting severe pain should be addressed. It is impossible to assess pain in addicted individuals, for their complaints are embedded into their need for medication. Temperament and mood should be evaluated carefully; the physician must remember that the depressed patient often denies feeling dysphoric and may even occasionally smile. The use of alcohol to self-medicate for pain usually indicates a depressive illness or lifelong alcohol dependence. When no medical, neurologic, or psychiatric disease can be established, one may be resigned to managing the painful state by the use of nonnarcotic medications and periodic clinical reevaluations. Such a course, though not altogether satisfactory, is preferable to prescribing excessive opioids or subjecting the patient to unnecessary surgery.
Chronic Pain of Indeterminate Cause
Pain in the thorax, abdomen, flank, back, face, head, or other part that cannot be traced to any visceral abnormality can create challenging clinical problems. In most cases, obscure neurologic sources, such as a spinal cord tumor and neuroma, have been excluded by repeated examinations and imaging procedures. A psychiatric disorder to which the patient’s symptoms and behavior might be attributed cannot be discerned. Yet the patient complains continuously of pain, is disabled, and spends a great deal of effort and resources seeking medical aid.
In such a circumstance, some physicians and surgeons, rather than concede their helplessness, may resort to extreme measures, such as exploratory thoracotomy, laparotomy, or laminectomy. Or they may injudiciously attempt to alleviate the pain and avoid drug addiction by severing roots and spinal tracts, often with the result that the pain moves to an adjacent segment or to the other side of the body.
This type of patient benefits from being seen frequently by the same physician. All the medical facts should be reviewed and the clinical and laboratory examinations repeated if some time has elapsed since they were last done. Tumors in the hilum of the lung or mediastinum; in the retropharyngeal, retroperitoneal, and paravertebral spaces; or in the uterus, testicle, kidney, or prostate pose a special difficulty in diagnosis and are often undetected for many months. More than once, we have seen a patient for months before a kidney or pancreatic tumor became apparent. Neurofibroma causing pain in an unusual site, such as one side of the rectum or vagina, is another type of tumor that may defy diagnosis for a long time.
Truly neurogenic pain is almost invariably accompanied by alterations in cutaneous sensation and other neurologic signs, the finding of which facilitates diagnosis; however, the appearance of the neurologic signs may be delayed—for example, in brachial neuritis. Whether investigation for earlier mentioned abnormalities of the sodium and potassium channels in cases of idiopathic severe unexplained pain is advisable has not been established. The frequent attribution of such pains to an unspecified small fiber neuropathy may be valid but also requires further study.
Because of the complexity and difficulty in diagnosis and treatment of chronic pain, most medical centers have found it advisable to establish pain clinics. Here a staff of physiatrists, internists, anesthesiologists, neurologists, neurosurgeons, and psychiatrists can review each patient in terms of drug dependence, neurologic disease, and psychiatric problems. Success is achieved by treating each aspect of chronic pain, addressing the individual’s problems rather than treating the pain generically, with emphasis on increasing the patient’s tolerance of pain by means of biofeedback, meditation, and related techniques; by using special analgesic procedures (discussed later in the chapter); by establishing a regimen of pain medication that does not lead to a rebound exaggeration of pain between doses; and by controlling depressive illness.
Rare and Unusual Disturbances of Pain Perception