With a 3‐fold increase in the number of cancer survivors noted since the 1970s, there are now over 28 million cancer survivors worldwide. Accordingly, there is a heightened awareness of long‐term toxicities and the impact on quality of life following treatment in cancer survivors. This review will address the increasing importance and challenge of chemotherapy‐induced neurotoxicity, with a focus on neuropathy associated with the treatment of breast cancer, colorectal cancer, testicular cancer, and hematological cancers. An overview of the diagnosis, symptomatology, and pathophysiology of chemotherapy‐induced peripheral neuropathy will be provided, with a critical analysis of assessment strategies, neuroprotective approaches, and potential treatments. The review will concentrate on neuropathy associated with taxanes, platinum compounds, vinca alkaloids, thalidomide, and bortezomib, providing clinical information specific to these chemotherapies. CA Cancer J Clin 2013;63:419‐437. ^© 2013 American Cancer Society, Inc.

Bell's palsy is a common cranial neuropathy causing acute unilateral lower motor neuron facial paralysis. Immune, infective and ischaemic mechanisms are all potential contributors to the development of Bell's palsy, but the precise cause remains unclear. Advancements in the understanding of intra-axonal signal molecules and the molecular mechanisms underpinning Wallerian degeneration may further delineate its pathogenesis along with in vitro studies of virus-axon interactions. Recently published guidelines for the acute treatment of Bell's palsy advocate for steroid monotherapy, although controversy exists over whether combined corticosteroids and antivirals may possibly have a beneficial role in select cases of severe Bell's palsy. For those with longstanding sequaelae from incomplete recovery, aesthetic, functional (nasal patency, eye closure, speech and swallowing) and psychological considerations need to be addressed by the treating team. Increasingly, multidisciplinary collaboration between interested clinicians from a wide variety of subspecialties has proven effective. A patient centred approach utilising physiotherapy, targeted botulinum toxin injection and selective surgical intervention has reduced the burden of long-term disability in facial palsy.

Amyotrophic lateral sclerosis (ALS) is a universally fatal neurodegenerative disease of the human motor system. Aetiological mechanisms implicated in the development of ALS have been linked to the glutamatergic neurotransmitter system, with destruction of motor neurons triggered through excessive activation of glutamate receptors at the synaptic cleft. This ‘excitotoxicity’ theory of ALS gave rise to the development of therapeutic approaches and ultimately clinical trials involving riluzole, initially thought to act solely as an inhibitor of glutamate release. Subsequent effects of riluzole have been postulated to include indirect antagonism of glutamate receptors, in addition to inactivation of neuronal voltage-gated Na+ channels. Riluzole remains the only disease-modifying therapy available to patients with ALS. Despite having been clinically available since the mid-1990s, the in vivo pharmacological targets of riluzole have been poorly defined. An improved understanding concerning the potential neuroprotective mechanisms of riluzole may unearth pathophysiological processes that mediate neurodegeneration in ALS. The present review summarises the known chemical and pharmacological properties of riluzole. The failure of other putative neuroprotective therapies to demonstrate positive treatment outcomes in this intractable disease will be reviewed. Finally, the hypothesis that Na+ conductances may be involved in the processes of neuronal and axonal degeneration in ALS will be explored.

Administration of oxaliplatin, a platinum-based chemotherapy used extensively in the treatment of colorectal cancer, is complicated by prominent dose-limiting neurotoxicity. Acute neurotoxicity develops following oxaliplatin infusion and resolves within days, while chronic neuropathy develops progressively with higher cumulative doses. To investigate the pathophysiology of oxaliplatin-induced neurotoxicity and neuropathy, clinical grading scales, nerve conduction studies and a total of 905 axonal excitability studies were undertaken in a cohort of 58 consecutive oxaliplatin-treated patients. Acutely following individual oxaliplatin infusions, significant changes were evident in both sensory and motor axons in recovery cycle parameters (P < 0.05), consistent with the development of a functional channelopathy of axonal sodium channels. Longitudinally across treatment (cumulative oxaliplatin dose 776 ± 46 mg/m²), progressive abnormalities developed in sensory axons (refractoriness P ≤ 0.001; superexcitability P < 0.001; hyperpolarizing threshold electrotonus 90–100 ms P ≤ 0.001), while motor axonal excitability remained unchanged (P > 0.05), consistent with the purely sensory symptoms of chronic oxaliplatin-induced neuropathy. Sensory abnormalities occurred prior to significant reduction in compound sensory amplitude and the development of neuropathy (P < 0.01). Sensory excitability abnormalities that developed during early treatment cycles (cumulative dose 294 ± 16 mg/m² oxaliplatin; P < 0.05) were able to predict final clinical outcome on an individual patient basis in 80% of patients. As such, sensory axonal excitability techniques may provide a means to identify pre-clinical oxaliplatin-induced nerve dysfunction prior to the onset of chronic neuropathy. Furthermore, patients with severe neurotoxicity at treatment completion demonstrated greater excitability changes (P < 0.05) than those left with mild or moderate neurotoxicity, suggesting that assessment of sensory excitability parameters may provide a sensitive biomarker of severity for oxaliplatin-induced neurotoxicity.