Neurophysiologic assessment of sensory denervation in chemotherapy induced polyneuropathy

Abstract

In patients with suspicion of chemotherapy induced polyneuropathy (CI-PNP), demonstration of large- and small fiber sensory polyneuropathy (LFN and SFN, respectively) is essential to decide alteration or cessation of chemotherapy. Thirty patients with complaints suggesting CI-PNP due to treatment with oxaliplatin or docetaxel were compared with 27 healthy subjects. All subjects were evaluated with nerve conduction studies (NCS), quantitative sensory testing (QST), laser evoked potentials (LEP). In addition, SFN in CI-PNP patients were assessed using cutaneous silent periods evoked with electrical (El-CSP) and laser (Ls-CSP) stimuli. NCSs, QSTs, LEPs, Ls-CSPs, and El-CSPs were abnormal in 27(90%), 28(93.3%), 16 (53.3%), 19 (63.3%), and 26 (86.6%) patients, respectively. El-CSP durations recorded from hands were significantly longer and El-CSP durations recorded from legs were significantly shorter than the controls. And, Ls-CSPs in hands were unavailable in 18 patients but available in all controls. NCS is the cornerstone to diagnose LFN. For SFN, LEPs showed moderate sensitivity. Unavailable Ls-CSP could be considered to confirm SFN in patients with suspicious LEPs (e.g., available but relatively small potentials). And, El-CSPs can be considered to diagnose CI-PNP induced SFN in laboratories using conventional neurophysiologic equipment. QSTs are informative for both LFN and SFN but the process needed to interpret the data limits their utility in daily practice.