Prospective nerve conduction studies in cisplatin therapy

Neurophysiological and clinical outcomes in chemotherapy-induced neuropathy in cancer

Chemotherapy induced peripheral neuropathy (CIPN) is a significant toxicity of cancer treatment, with the potential to affect long-term function and quality of life in cancer survivors. There remains a lack of consensus around optimal assessment techniques. While current approaches to CIPN assessment are focused on clinical grading scales, it is becoming increasingly evident that a more comprehensive multimodal assessment package is necessary to accurately characterise the impact of CIPN as well as gauge the utility of neuroprotective mechanisms. Neurophysiological techniques provide objective biomarkers and may enable early detection of toxicity while patient reported outcomes are necessary to determine the significance of symptoms to individual patients. In addition to providing an objective assessment, clinical neurophysiological techniques provide important insights into the contributory pathophysiological mechanisms of CIPN with different chemotherapy agents. There is a paucity of implementation of these techniques in the clinical trial setting. The present Review aims to facilitate the use of neurophysiological studies as part of comprehensive assessment packages for the monitoring of CIPN by summarising current understanding of neurophysiological changes that underlie the development of neuropathy, clinical presentations and patient reported outcomes as well as advantages and limitations of current techniques for the neurophysiological assessment of CIPN.

Docetaxel in ovarian cancer

Docetaxel, a semisynthetic taxane, is a potent inhibitor of cell replication and, similar to paclitaxel, promotes in vitro assembly of stable microtubules and, therefore, prevents the depolymerisation process. Docetaxel has a higher affinity for the tubulin subunit and is associated with a 100-fold greater phosphorylation of BCL-2 inducing apoptosis. Docetaxel in combination with carboplatin demonstrates similar activity to paclitaxel/carboplatin in the upfront management of advanced ovarian cancer with less neurological, but greater haematological toxicity. This article reviews the rationale and indications for the use of docetaxel in ovarian cancer.

Oxaliplatin-induced neurotoxicity: acute hyperexcitability and chronic neuropathy

Oxaliplatin, a platinum-based chemotherapeutic agent, is effective in the treatment of solid tumors, particularly colorectal cancer. During and immediately following oxaliplatin infusion, patients may experience cold-induced paresthesias, throat and jaw tightness, and occasionally focal weakness. We assessed nerve conduction studies and findings on needle electromyography of patients with metastatic colorectal cancer before and during treatment with oxaliplatin. Twenty-two patients had follow-up studies within 48 h following oxaliplatin infusions, and 14 patients had follow-up studies after 3-9 treatment cycles. Repetitive compound muscle action potentials and neuromyotonic discharges were observed in the first 24-48 h following oxaliplatin infusion, but resolved by 3 weeks. After 8-9 treatment cycles, sensory nerve action potential amplitudes declined, without conduction velocity changes or neuromyotonic discharges. The acute neurological symptoms reflect a state of peripheral nerve hyperexcitability that likely represents a transient oxaliplatin-induced channelopathy. Chronic treatment causes an axonal neuropathy similar to other platinum-based chemotherapeutic agents.

Neurotoxic complications of chemotherapy in patients with cancer: clinical signs and optimal management

Neurotoxic side effects of chemotherapy occur frequently and are often a reason to limit the dose of chemotherapy. Since bone marrow toxicity, as the major limiting factor in most chemotherapeutic regimens, can be overcome with growth factors or bone marrow transplantation, the use of higher doses of chemotherapy is possible, which increases the risk of neurotoxicity. Chemotherapy may cause both peripheral neurotoxicity, consisting mainly of a peripheral neuropathy, and central neurotoxicity, ranging from minor cognitive deficits to encephalopathy with dementia or even coma. In this article we describe the neurological adverse effects of the most commonly used chemotherapeutic agents. The vinca-alkaloids, cisplatin and the taxanes are amongst the most important drugs inducing peripheral neurotoxicity. These drugs are widely used for various malignancies such as ovarian and breast cancer, and haematological cancers. Chemotherapy-induced neuropathy is clearly related to cumulative dose or dose-intensities. Patients who already have neuropathic symptoms due to diabetes mellitus, hereditary neuropathies or earlier treatment with neurotoxic chemotherapy are thought to be more vulnerable for the development of chemotherapy-induced peripheral neuropathy. Methotrexate, cytarabine (cytosine arabinoside) and ifosfamide are primarily known for their central neurotoxic side effects. Central neurotoxicity ranges from acute toxicity such as aseptic meningitis, to delayed toxicities comprising cognitive deficits, hemiparesis, aphasia and progressive dementia. Risk factors are high doses, frequent administration and radiotherapy preceding methotrexate chemotherapy, which appears to be more neurotoxic than methotrexate as single modality. Data on management and neuroprotective agents are discussed. Management mainly consists of cumulative dose-reduction or lower dose-intensities, especially in patients who are at higher risk to develop neurotoxic side effects. None of the neuroprotective agents described in this article can be recommended for standard use in daily practise at this moment, and further studies are needed to confirm some of the beneficial effects described.

Drug-induced myopathy and neuropathy

We review the drugs that are known to induce muscle and/or nerve toxicity, describe the commonly encountered signs and symptoms, and discuss the mechanisms believed to be behind these iatrogenic effects. The diagnostic approach to patients suspected of having drug-induced neuromuscular disorders includes a comprehensive history and physical examination, proper blood workup, electrophysiological studies, and, if necessary, muscle or nerve biopsy. A lot of controversial issues continue to prevail when reviewing such a topic, secondary to the greatly variable levels of certainty for the association between drugs and their neuromuscular toxicity. We focus on drugs that are proven to cause these adverse effects, with less emphasis on the anecdotally suspected agents for which coincidence has not been eliminated.

Evaluation of long-term toxicity in patients after cisplatin-based chemotherapy for non-seminomatous testicular cancer

BACKGROUND

Because of the increasing number of long-term survivors of metastatic testicular germ-cell cancer, a general concern has been secondary morbidities, especially cardiovascular risk factors.

PATIENTS AND METHODS

Thirty-two patients treated with cisplatin- and doxorubicin-containing chemotherapy > or = 13 years before the time of analyses were evaluated for neuro-, oto-, pulmonary-, vascular- and gonadal toxicity including evaluation of myocardial damage and cardiovascular risk factors and analysis of microcirculation.

RESULTS

Thirty percent of the patients showed abnormal left ventricle function. Elevated follicle stimulating hormone (FSH) and luteinising hormone (LH) levels in 75% of patients were often associated with low testosterone levels. Elevated total cholesterol levels were found in 82% and higher triglyceride levels in 44% of patients, most of them were overweight. About 25% of the patients developed diastolic arterial hypertension after chemotherapy. Reduced hearing was confirmed in 23% of patients, especially at frequencies higher than 3000 Hz. Moreover, 53% of patients presented transient evoked otoacoustic emissions. In 38% of patients non-symptomatic neuropathy was detected, in 28% symptomatic neuropathy, and in 6% disabling polyneuropathy. In 80% of patients with neuropathic symptoms additional morphological and functional abnormalities were found by nailfold capillary videomicroscopy, compared to only 57% of the patients without neuropathic symptoms.

CONCLUSIONS

Patients cured by cisplatin-based chemotherapy for metastatic testicular cancer have to be cognizant of their unfavorable cardiovascular risk profile, that might be a greater risk than developing a relapse or second malignancy.

Cisplatin neurotoxicity in the treatment of metastatic germ cell tumour: time course and prognosis

In order to ascertain the incidence and prognosis of cisplatin-induced neurotoxicity in testis cancer patients undergoing combination chemotherapy, 29 patients with metastatic disease were studied prospectively. Assessments included enquiry into neurological symptoms, measurement of sural nerve sensory action potential and conduction velocity, and vibration threshold in the left big toe. At the end of chemotherapy (3 to 4 cycles) only 3 out of 26 (11%) patients had paraesthesiae, but 3 months later the proportion rose to 65%. Resolution occurred in the majority over the ensuing 12 months so that only 17% had persistent symptoms. None of the 11 patients treated with 3 cycles of chemotherapy had persisting symptoms. Vibration thresholds showed a significant deterioration during chemotherapy (P = 0.032), further deterioration in the 3 months following chemotherapy (P = 0.009) and significant improvement between 3 and 12 months after chemotherapy (P = 0.038). Sural nerve sensory action potentials and conduction velocities were unhelpful.

Peripheral neurotoxic disorders

The effects of several substances known to produce peripheral neuropathy are reviewed, as are the criteria espoused to be useful in establishing their neurotoxicity. Included is a description of systemic and neurologic symptoms and signs important in identification of the neurotoxic disorder, and a description of the resultant electrodiagnostic abnormalities.

In vitro protection from cisplatin-induced neurotoxicity by amifostine and its metabolite WR1065

Cisplatin-induced neuropathy is a major dose-limiting toxicity. Counteraction by amifostine and its metabolite WR1065 may reduce peripheral neurotoxicity in a number of patients. Using the nerve growth factor (NGF)-dependent neurite outgrowth from the PC12 pheochromocytoma cell line as an in vitro assay for neurotoxicity, the protective effects of amifostine and WR1065 against cisplatin action on neurite formation by PC12 cells were studied. Cisplatin in a concentration of 10 microg/ml significantly decreased the percentage of neurite forming cells from 84% to 40%. Amifostine in doses of 0.4 and 0.8 mM proved to protect significantly against the cisplatin-induced decrease in neurite formation, when co-incubated with cisplatin. Also the metabolite WR1065 protected significantly against cisplatin neurotoxicity in a dose of 0.12 mM. Our results show a significant protection by amifostine and its main metabolite WR1065 against cisplatin-induced neurotoxicity using an in vitro model.

Physiological and immunohistochemical characterization of cisplatin-induced neuropathy in mice

We investigated the neuropathic effects of cisplatin in two groups of mice treated with 5 or 10 mg/kg/week of cisplatin for 7 or 8 weeks. Peripheral nerve functions were evaluated by sweat imprints, and electrophysiological, rotarod, and nociceptive tests. Protein gene product 9.5 (PGP), calcitonin gene-related peptide (CGRP), and vasoactive intestinal peptide (VIP) were immunohistochemically localized in footpads. Tibial nerves were analyzed morphometrically. Functional deficits developed progressively with higher cumulative doses, more markedly in mice treated with high than in those with low doses. From cumulative doses of 10 mg/kg, significant declines in sensory nerve conduction velocity and sudomotor responses were found, whereas motor and nociceptive functions were involved later. There were no morphometrical changes in tibial nerves. A marked decrease of CGRP- and VIP-immunoreactive nerves occurred in samples from treated mice, whereas PGP-labeled profiles decreased mildly at late stages. Impairment of the content of neuropeptides with neurosecretor role was detectable earlier than functional abnormalities. Immunohistochemical analysis of skin biopsies offers a useful diagnostic tool for peripheral neuropathies.

Histology and platinum content of sensory ganglia and sural nerves in patients treated with cisplatin and carboplatin: an autopsy study

Cisplatin is a valuable antineoplastic drug which as a dose-limiting side-effect causes sensory neuropathy, and which therefore is often combined with less neurotoxic carboplatin. It has not been possible to reproduce cisplatin neuropathy in experimental animals, and the neurotoxic mechanism in man is disputed. We investigated post-mortem material from 12 patients and 15 control subjects. Half of the fibres with diameters of > or = 9 microns, or more than 15% of all fibres (P < 0.02), had disappeared in the sural nerves of patients. Signs of axonal regeneration were lacking. The dorsal root ganglia D12 and L2 of some but not of all patients contained necrotic neurons and nodules of Nageotte. The mean volume of the somata was reduced by 18% (P < 0.03). A relation between cumulated doses, treatment free interval and changes in nerve or ganglia was not found. The platinum content was high in all tissues except in the spinal cord when the patient had died shortly after treatment, and it decreased with increasing interval, least so in liver, sensory ganglia and sural nerves. The results support the hypothesis that cisplatin neuropathy is a neuroneopathy rather than a dying-back axonopathy.

Protective effects of glutathione on cisplatin neurotoxicity in rats

PURPOSE

Different attempts have been made to minimize the neurotoxicity of cisplatin (DDP) and the use of "neuroprotective" drugs seems to be a promising strategy. In rats we compared the effects on the dorsal root ganglia neurons and peripheral nerves of the administration of DDP alone or in combination with glutathione (GSH), a putative "neuroprotective" drug.

METHODS AND MATERIALS

Twenty-four Wistar rats were treated with DDP alone (2 mg/kg/week) or with the same dose of DDP plus GSH (300 mg/week) for nine cycles and they were compared to 12 untreated age-matched rats. All the animals underwent either neurophysiological examination of the tail nerve or pathologic examination of the dorsal root ganglia. Analytical determination of the platinum concentration in dorsal root ganglia was also performed.

RESULTS

Morphologic and morphometric evaluations demonstrated a reduced incidence of pathologic changes in DDP plus GSH-treated rats with respect to DDP-treated ones. In agreement with the morphological findings, the platinum concentration in the dorsal root ganglia was lower and sensory nerve conduction velocity in the tail nerve less markedly decreased in the animals treated with DDP plus GSH with respect to those treated with DDP alone.

CONCLUSION

We conclude that the administration of GSH is effective in reducing the neurotoxic effects of DDP, thus supporting the preliminary results obtained in clinical trials in humans.

Morphometric study of the sensory neuron and peripheral nerve changes induced by chronic cisplatin (DDP) administration in rats

We performed a morphological, morphometric and toxicological study on the spinal ganglia and peripheral nerves of the rat after chronic administration of cisplatin (cis-dichlorodiammineplatinum II; DDP) with two different schedules. Severe damage of the spinal ganglia neurons was demonstrated with predominant involvement of the nucleus and nucleolus associated with a decrease in the cell size. Morphological and morphometric changes also occurred in the sciatic and peroneal nerves with the features of axonopathy. All these changes were more marked in the group of rats which underwent the most intense DDP treatment and the tissue platinum concentrations were also higher in this group. This experimental model is the first available for chronic DDP administration in which concomitant spinal ganglia and peripheral nerve damage has been confirmed pathologically. Our study supports the hypothesis that DDP-induced peripheral nerve fiber degeneration may result from nuclear and nucleolar changes in the sensory ganglion cell perikaryon.

Cisplatin neuropathy: clinical course and neurophysiological findings

Sixteen patients treated with cisplatin (CDDP) 40 mg/m2 on days 1-5 every 4 weeks for three courses (cumulative dose 600 mg/m2) were clinically and neurophysiologically tested before, during and 1, 3, 6, 9 and 12 months after CDDP administration. The first symptoms of polyneuropathy occurred in 4 of 9 patients after the second course (cumulative dose 400 mg/m2). One month after treatment 1 of 9 patients was asymptomatic, 5 complained of symptoms and 3 showed clinical and neurophysiological signs of polyneuropathy. Three months after CDDP all patients were affected. Clinical and neurophysiological signs of severity progression were noted up to 6 months after treatment with CDDP.

Cisplatin-induced peripheral neurotoxicity is dependent on total-dose intensity and single-dose intensity

The authors prospectively evaluated the effects of three different schedules of cisplatin (DDP) administration in 60 patients with advanced epithelial ovarian cancer. The individual total dose of DDP was 450 mg/m2 in all three groups, and the anti-cancer response at the end of treatment was similar for the different regimens. The clinical and neurophysiologic results confirmed that axonal sensory neuropathy occurred after the standard administration of DDP (75 mg/m2 in 3-week cycles) and probably not only the peripheral, but also the central sensory pathway, was involved. Although the total dose of the drug was identical, the two less conventional schedules were less neurotoxic. These results suggest that not only the total-dose intensity, but also the single-dose intensity are relevant in the onset of DDP-induced sensory neuropathy; therefore, the use of less neurotoxic schedules may prevent or reduce sensory nerve damage.

Cisplatin induced neuropathy: central, peripheral and autonomic nerve involvement

A prospective study was performed in patients treated with cisplatin to evaluate the occurrence and degree of central, peripheral and autonomic neuropathy and to determine the most accurate method to study this neuropathy. Twelve patients were examined before, during and after treatment. Evaluation included neurologic examination, conventional nerve conduction studies of the median and peroneal nerves and short latency somatosensory evoked potentials (SSER) after median and tibial nerve stimulation. Valsalva maneuvers before and during treatment were performed in 11 patients. Symptoms of peripheral neuropathy paralleled clinical signs. Conventional nerve conduction studies did not seem to be more accurate than clinical examination in determining peripheral neuropathy. SSER appeared to be the most sensitive method for the detection of peripheral nerve impairment. A slowing of central conduction velocity occurred after cumulative doses of 200-400 mg/m2 as measured by SSER. In two patients also some involvement of the autonomic nerves was suggested.

AAEM minimonograph #34: polyneuropathy: classification by nerve conduction studies and electromyography

Electrodiagnostic evaluation of patients with suspected polyneuropathy is useful for detecting and documenting peripheral abnormalities, identifying the predominant pathophysiology, and determining the prognosis for certain disorders. The electrodiagnostic classification of polyneuropathy is associated with morphologic correlates and is based upon determining involvement of sensory and motor fibers and distinguishing between predominantly axon loss and demyelinating lesions. Accurate electrodiagnostic classification leads to a more focused and expedient identification of the etiology of polyneuropathy in clinical situations.

Cisplatin-induced peripheral neuropathy. Frequent off-therapy deterioration, demyelinating syndromes, and muscle cramps

Forty-five patients with cisplatin-induced peripheral neuropathy (PN) were evaluated retrospectively after treatment with cumulative doses of cisplatin ranging from 201 to 1952 mg/m2. The patients were followed for up to 23 months (median, 4.5 months), and 32 of them were evaluated more than once. Severity of symptoms was related to higher cumulative doses of cisplatin but with marked individual variability. Off-therapy deterioration of the PN continued in 14 patients (31%) for 2.5 to 5.5 months after withdrawal of cisplatin, and only four patients showed some improvement during the follow-up period. Symptomatic deterioration often was heralded by new onset of muscle cramps (with normal Ca2+/Mg2+ levels) and/or by manifestations of probable spinal dorsal column and/or nerve root demyelinating syndromes presenting as either Lhermitte's sign and/or as an electric-shock sensation along the upper extremities when outstretched in 90 degrees shoulder abduction. Cramps and demyelinating syndromes were each noted in 31% of the patients. Muscle cramps tended to resolve several months after withdrawal of therapy, and demyelinating syndromes were always transient (1.5 to 6.0 months) and did not progress despite ongoing therapy in five patients. Our study indicates that, after withdrawal of therapy, patients with cisplatin-induced PN may continue to deteriorate for several months. Manifestations of muscle cramps and demyelinating syndromes signify a worsening course of the PN but should not automatically indicate interruption of therapy.