Contralateral Ulcers Underscore Value of Nerve

Decompression

by Jordana Bieze Foster
BioMechanics Magazine
February, 2005

Given that A. Lee Dellon, MD, has yet to see an ulceration in any of the neuropathic limbs he's treated with surgical decompression, it may not be surprising that most of his patients eventually undergo the procedure in both limbs. But a December report on ulceration rates in the contralateral limbs of those treated only once underscores the effectiveness of the procedure.

In 50 patients who underwent surgical decompression in one limb but not the other, Dellon and colleagues reported 12 ulcers and three amputations in the contralateral limbs but no ulcers or amputations in the treated limbs a mean of 4.5 years after surgery. The results were published in the Annals of Plastic Surgery.

The triple nerve decompression procedure, in which ligament release relieves pressure on the tibial, deep peroneal, and common peroneal nerves, was first described by Dellon in Plastic Reconstructive Surgery in April 1992. In that study and six others published by Dellon and his trainees since then, the procedure has been associated with pain relief in 85% to 92% of patients and improved sensation in 50% to 72% of patients. In those study populations combined, no ulcers developed in any of the patients with no previous history of ulceration, and just one ulcer developed in the 29 patients with a history of ulceration. Dellon, a professor of neurosurgery and plastic surgery at Johns Hopkins University, puts the overall success rate at 80%.

Almost all of those in whom the initial procedure is successful return for treatment on the contralateral limb, he said.

"The overall success rate is 80% and so it is reasonable that 80% do come back to do the other side," Dellon said. "The patients who have easy access to care or who can afford to travel, or who do not have concurrent disease (like a heart attack or renal failure) do come back."

Despite these results, however, Dellon said he would not recommend performing the surgery in both limbs simultaneously, even if doing so might obviate a return visit.

"We need the patient to have one leg to use to ambulate, and since the success rate is not 100% we want to be sure we have helped one leg before we operate on the other one," he said.

In an effort to close in on that 100% success rate, Dellon and colleagues are working to identify more specifically those patients who are most likely to benefit from the procedure. In a separate study published in the same issue of the same journal, results from 86 patients confirm the researchers' long-held hypothesis that a positive Tinel's sign (distally radiating paresthesia in response to gentle percussion) is predictive of favorable outcomes.

"With chronic compression of a peripheral nerve, there occurs first demyelination and then axonal degeneration. The demyelination makes the nerve more susceptible to biomechanical forces and permits easier initiation of a conducted potential (nerve impulse)," Dellon said.

Positive outcomes were defined by pain levels that improved more than five points on a 10-point visual analog scale, or any improvement in two-point discrimination as measured using a Pressure-Specified Sensory Device.

Patients whose baseline pain levels exceed 5 on the VAS and/or whose PSSD results indicated axonal loss within a greater than 99% confidence limit generally undergo surgery when they demonstrate a positive Tinel's sign, Dellon said.