Testing protocol unlocks mystery of chronic pain

Research may hold the key to reducing disability

Early research results from a new testing protocol developed by a researcher at Yale Center for Pain Management in New Haven, CT, may offer the first real tool for preventing chronic industrial disability and save employers and payers thousands in disability costs.

"I started with a clinical impression that patients with reflex sympathetic dystrophy (RSD) and complex regional pain syndrome seemed to manifest similar, subtle characteristic abnormalities of sensation of the head and neck. This suggested an underlying neurological condition that predisposed them to chronic pain conditions," says Mark Thimineur, MD, with the Yale Center for Pain Management and assistant professor at Yale University School of Medicine.

"The MRIs [magnetic resonance imaging] on these patients were usually normal. We had a difficulty convincing anybody, even ourselves, that these clinical similarities were real," says Thimineur. "This lead to the development of a protocol using six noninvasive tests of neuro- logical function to the pathways in the central nervous system important in transmitting pain and controlling motor function," he says.

Tests can be done in one day

The six tests used by Thimineur to quantitatively evaluate neurologic function of chronic pain patients cost about $900 and can be done in one day. "We schedule out-of-town patients so that the tests can be done in one day with a break for lunch," says Kathy Carboni, RN, BSN, with Yale Center for Pain Management. The center has arranged a discounted rate at an adjacent hotel for patients who must stay overnight.

Thimineur hopes to streamline the testing process and decrease the cost to about $600 and the testing time down to two hours. The six tests in the protocol include:

• quantitative somatosensory thermotest;

• Semmes-Weinstein filament test;

• pressure algometry;

• taste studies;

• isokinetic strength evaluation;

• isometric evaluation.

"Test results can usually be printed out the same day. I schedule patients so that the last person they see is the doctor. The doctor has all the results available and can go over them with the patients and make recommendations," says Carboni.

The six tests are structured into a standard protocol designed to evaluate brainstem and spinal cord function. Using this protocol, the evidence began to support Thimineur’s theory. Of 133 RSD patients tested, 67% met the criteria for cervicomedullary dysfunction. This included a specific pattern of sensory loss of the face and tongue with same side sensory derangement of the body, which was always on the side that the RSD was located. "Only seven of those 136 patients with sensory derangement had abnormal MRIs. All seven had abnormalities of the lower brainstem," Thimineur says. In fact, the syndrome compares favorably with neurologic deficits seen in certain types of brainstem vascular events, or stroke. The changes are just more subtle."

Thimineur has observed similar findings in many patients with chronic low back pain. "In back pain patients, we see more evidence of cervical spine disease and confirmatory MRIs. We often find that leg symptoms — such as weakness — in low back pain are attributable to unrecognized cervical cord compression," he adds.

The evidence Thimineur is gathering about the underlying cause of chronic pain holds enormous implications for case managers. "We believe that with further research, we will be able to identify patients that are at high risk for developing chronic pain and disability," he says. "Right now, we are seeing patients after they have already had several surgeries and therapy. If we could see them earlier, we may be able to identify a significant number of patients who are predisposed to bad outcomes."

"The cost factor of this testing protocol is not unreasonable compared to other tests we use regularly," says Susan Trevethan, RNC, CCM, disability nurse administrator for Pitney Bowes in Stamford, CT. "Consider a situation where one physician is recommending surgery for a patient and another is recommending against surgery. What if you had the information you needed to show that surgery would create longer length of disability and a poor outcome? That would be very useful information.

"When I was with Traveler’s, I routinely saw patients who had had 10 or more surgeries, all of which failed. Think if you could prevent that kind of course," says Trevethan, who recently left her position as a case manager for Traveler’s Medical Management Services in Milford, CT.

Trevethan sees other applications for the new testing protocol as well. "When physicians have a patient who is in chronic pain without any definitive diagnosis, case managers suddenly see a diagnosis of RSD. The physician has nowhere else to turn. It’s the last-ditch diagnosis. The testing protocol offers physicians something to hang their hats on," she says.

Thimineur adds that identifying the cause of chronic pain helps physicians structure realistic treatment plans. "We have seen a common pattern of functional decline and a spreading of pain and weakness in these patients with presumed brainstem abnormalities. We also see rather consistent symptoms of brainstem dysfunction develop, such as headaches and nausea. Knowing this, we are more capable of helping the patient and less overwhelmed by these confusing symptoms," he says.

"Realizing what we are dealing with also makes [physicians] more comfortable and compassionate in treating patients. In the past, many of these patients were assumed to be manifesting psychiatric symptoms," Thimineur says. "If we understand better the natural evo-lution of these neurological chronic pain states, we can further benefit people by acting preventatively and doing things like restructuring work environments, removing patients from potentially harmful work situations, and perhaps, avoiding a certain amount of permanent disability."

Patients also should benefit from knowing they have a "real" cause for their pain, notes Trevethan, who has referred several patients to the Yale Center for Pain Management.

"Patients with chronic pain syndromes, like RSD, often question themselves. If they realized that there was a physiological basis for their condition, it might help them cope better. They might be less likely to lean heavily on support groups and look instead to their physician for treatment," she says.

In the future, Thimineur hopes that the testing protocol can be made into a screening tool for industrial employees who may be predisposed to chronic pain and disability. "What if we could identify patients at risk for disability? This would allow meaningful preventative measures such as ergonomic changes for at risk employees, or perhaps, earlier vocational retraining," he says.

Thimineur already has started to test the general population of "healthy" working individuals as a comparison to his chronic pain patients. "Among our healthy working colleagues, there are about 7% who manifest similar changes to those identified in our chronic pain population," he says. "Of that 7%, many have reported chronic pain conditions, such as bursitis, which have not kept them off work but have kept them returning repeatedly to the doctor."

"What Thimineur has done at Yale is very exciting. Yale sees so many chronic pain patients in this academic setting that he has had the time and process to study them in a way other physicians can’t," Trevethan says. "Now, we need a larger study. We need hard numbers, a little more evidence. Once the numbers are there, the education process can begin for physicians and case managers.

"As a case manager, I know it’s important to have as much information as possible and use it to educate providers, claims people, and patients. I see a lot of application for this testing protocol in the future."

(Editor’s note: Mark Thimineur, MD, will be leaving the Yale Center for Pain Management in July 1997 for private practice.)