Bench to Bedside: Current Perception Threshold Testing (CPT) to Measure Sensory Fiber Changes After Chemotherapy

Tanguay, Lori J.

Saturday, 29 October 2011

Lori J. Tanguay, MS, RN, OCN¹
Susan G. Dorsey, PhD, RN²
Darren J. Couture, CRNA, MSN²
Cynthia Renn, PhD, RN²
Nancy Gambill, CRNP, OCN¹
(1)Marlene and Stewart Greenebaum Cancer Center, University of Maryland Medical Center, Baltimore, MD
(2)School of Nursing, University of Maryland, Baltimore, MD

Learning Objective 1: The learner will be able to describe the use of Current Perception Threshold Testing(CPT)to measure each of the three major types of sensory nerve fibers.

Learning Objective 2: The learner will be able to discuss the sensitivity and specificity of CPT testing in detecting sensory nerve fiber integrity in patients receiving chemotherapy.

Introduction: Chemotherapy induced peripheral neuropathy (CIPN) remains a significant complication of cancer treatment. For patients receiving taxanes and/or platinum chemotherapy, the incidence is as high as 84-100%. With no preventative or curative treatment, patients report symptoms ranging from constant numbness and tingling of the hands and/or feet to debilitating burning pain. Symptoms often persist for several months or even years after the completion of treatment. As no “gold standard” measure exists, diagnosis depends upon the patient’s report of symptoms, often when permanent neuronal injury has occurred. When symptoms limit function, current practice is to limit or discontinue treatment. A need exists for a standard measure to accurately identify and predict CIPN, in an effort to limit long-term neuronal damage and improve prognosis.

Purpose: The study purpose was to determine if CPT measurement accurately identifies CIPN and whether this measure predicts CIPN in patients receiving taxane and/or platinum regimens.

Methods: This prospective study enrolled 35 chemotherapy naïve participants. Subjective and objective measurements, including CPT were collected during each chemotherapy treatment visit to assess sensory nerve function and the development of CIPN.

Results: At 2000 Hz, 250 Hz, and 5 Hz, the CPT identified 78%, 56%, and 33% of participants who developed CIPN, respectively. However, the false-positive rate was 70%, 50%, and 45%, respectively. Generalized linear mixed model analysis determined the only CPT frequency to predict the outcome of CIPN was at 250 Hz. A one unit increase in CPT at this frequency, increase the odds by 0.3% that a patient developed CIPN (OR=1.003, 95% CI=1.001-1.006, p=0.01).

Discussion: While this measure accurately identfied a majority of patients with CIPN at 2000 Hz, the false-postive rate was unnacceptibly high. No known studies to date have demonstrated the predictive capability of using CPT in this patient population. Further investigations are required to demonstrate repeatability of these results.

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