Grading of chemotherapy-induced peripheral neuropathy.

Peripheral neuropathy can be defined as a derangement in structure and function of peripheral motor, sensory, and autonomic neurons [1], causing peripheral neuropathic symptoms and signs. In routine clinical practice settings, neuropathic symptoms are evaluated by a more or less standardized neurological history taking. Assessment of neuropathic signs is usually performed with bed-side clinical examination (sensory and motor abnormalities, reflex loss, orthostatic hypotension, etc.) or with quantitative methods such as nerve conduction studies, electromyography, and quantitative sensory threshold determination [2]. Peripheral neuropathy is observed frequently in patients treated with neurotoxic chemotherapeutic agents, including cisplatin, vincristine, and paclitaxel [3]. Vincristine and paclitaxel-induced neuropathy tend to occur early during therapy, with amelioration after discontinuation of therapy, whereas cisplatin-induced neuropathy tends to develop only after a certain cumulative dose level, and frequently worsens during the first months after therapy discontinuation [4]. Chronic peripheral neuropathy is a fairly common observed phenomenon, especially with cisplatin, and may lead to substantial negative impact on quality of life [5]. Chemotherapy-induced peripheral neuropathy is usually related to cumulative dose or dose-intensity, and with the advent of bone marrow stimulants like granulocyte colony-stimulating factor, precluding dose-limiting bone marrow toxicity, higher chemotherapy doses are used [6]. The development of regimens combining neurotoxic chemotherapeutic agents (e.g., cisplatin and paclitaxel) may also induce more pronounced or even dose-limiting peripheral neurotoxicity [7], necessitating reliable assessment of chemotherapy-induced peripheral neurotoxicity. This is certainly mandatory when the effects of potential neuroprotective agents are to be studied. However, the assessment of the severity of chemotherapy-induced neuropathy is difficult. This review article will discuss the various ways of assessing chemotherapy-induced peripheral neuropathy, and will emphasize the need for reliable grading of severity of this toxicity, including a quality of life estimate.