Value of a Good Outcome to Carpal Tunnel Decompression in Predicting Success with Lower Extremity Peripheral Nerve Decompression in Patients with Neuropathy

Many patients with neuropathy present with pain and numbness in a glove and stocking distribution. For years, patients treated successfully with carpal tunnel releases were told there was nothing that could be done about their lower extremity symptoms. Now that lower extremity nerve decompression has been accepted as an option to treat appropriate patients with lower extremity neuropathy complaints, the authors looked for correlations between a successful outcome with carpal tunnel syndrome and its predictive value of success in lower extremity nerve decompression.

A retrospective cohort study was designed from a database of 200 patients who had previous decompression of the lower extremity peripheral nerves to restore sensation and to relieve pain in their feet. Inclusion criteria for the study were 1) a history of carpal tunnel decompression prior to the date of lower extremity peripheral nerve surgery; and 2) presence of neuropathy. Thirty-six patients were selected for inclusion. Their original consultation note was reviewed to determine their stated outcome to the carpal tunnel surgery and this answer, dichotomized into either a good/excellent or fair/poor result was compared to their dichotomized result from their lower extremity peripheral nerve surgery.

Thirty-four of the 35 patients had a good/excellent response to the carpal tunnel release. Thirty of the 34 patients who had a good response to carpal tunnel release had a good/excellent response to the lower extremity peripheral nerve decompression. Chi-square analysis of these data yielded a sensitivity of 97% (30/31), a specificity of 0% (0/4), and a positive predictive value of 88% (30/34) for a good outcome from carpal tunnel decompression, to predict a good outcome from lower extremity peripheral nerve decompression.

During the history-taking part of the initial consultation with the patient with diabetic neuropathy involving the lower extremity, it is important to learn if the patient has upper extremity peripheral nerve symptoms and if there was a previous decompression of the median nerve in the carpal tunnel. This study demonstrates that a good result from upper extremity peripheral nerve surgery predicts the outcome from lower extremity peripheral nerve surgery in 88% of patients and is, therefore, information valuable for prognosis and clinical decision making.