Some features of the neuromuscular complications of pulmonary carcinoma

Orofacial pain in cancer: part II--clinical perspectives and management

Cancer-associated pain is extremely common and is associated with significant physical and psychological suffering. Unfortunately, pain associated with cancer or its treatment is frequently under-treated, probably due to several factors, including phobia of opioids, under-reporting by patients, and under-diagnosis by healthcare workers. The most common etiology of cancer pain is local tumor invasion (primary or metastatic), involving inflammatory and neuropathic mechanisms; these have been reviewed in Part I. As malignant disease advances, pain usually becomes more frequent and more intense. Additional expressions of orofacial cancer pain include distant tumor effects, involving paraneoplastic mechanisms. Pain secondary to cancer therapy varies with the treatment modalities used: Chemo-radiotherapy protocols are typically associated with painful mucositis and neurotoxicity. Surgical therapies often result in nerve and tissue damage, leading, in the long term, to myofascial and neuropathic pain syndromes. In the present article, we review the clinical presentation of cancer-associated orofacial pain at various stages: initial diagnosis, during therapy (chemo-, radiotherapy, surgery), and in the post-therapy period. As a presenting symptom of orofacial cancer, pain is often of low intensity and diagnostically unreliable. Diagnosis, treatment, and prevention of pain in cancer require knowledge of the presenting characteristics, factors, and mechanisms involved.

Paraneoplastic syndromes affecting the nervous system

The paraneoplastic neurologic disorders (PND) are a diverse group of diseases characterized by the presence of neurologic dysfunction in the setting of a remote cancer. PND can affect almost any part of the nervous system, and are most commonly associated with lung cancer (small cell) and gynecologic tumors. Laboratory studies have demonstrated that an autoimmune response links the neurologic disorder and the cancer, and established a model whereby the cancer is believed to initiate the syndrome by expressing a protein antigen normally expressed in the nervous system, leading to anti-tumor immune response followed by autoimmune neurologic symptoms. We review the currently known PND and their pathogenesis.

The neuropathology of paraneoplastic syndromes

The term "paraneoplastic neurological syndromes" encompasses a number of uncommon disorders associated with systemic malignancies. In order to be classified a paraneoplastic neurological syndrome, the malignancies must not invade, compress, or metastasize to the nervous system. They can either focally or diffusely involve the central and peripheral nervous system or the neuromuscular junction. This paper reviews the neuropathology of the syndrome. It will first describe the clinical presentation and give an account of the systemic tumors most commonly associated with the various types of disorders. Then it will review the general pathological features that consist of an inflammatory process predominantly affecting the gray matter. Finally, it will describe in detail the main clinico-pathological types, including 1) encephalomyelitis, 2) cortical cerebellar degeneration, 3) peripheral neuropathy, 4) opsoclonus-myoclonus and 5) retinopathy. The Lambert-Eaton myasthenic syndrome will be dealt with separately in another paper in this symposium.

Chemotherapy-induced peripheral neuropathy

PURPOSE/OBJECTIVES

To review the literature documenting the scope, treatment, and prevention of chemotherapy-induced neuropathy.

DATA SOURCES

Published abstracts, primary research literature, and textbook chapters.

DATA SYNTHESIS

Recent improvements in the management of other treatment-related toxicities have led to peripheral neuropathy becoming a dose-limiting toxicity of commonly used chemotherapeutic groups such as platinols, vinca alkaloids, and taxanes.

CONCLUSIONS

The nervous system has not been the focus of education or training for oncology nurses. Therefore, nurses' ability to educate patients regarding this aspect of their condition has been limited.

IMPLICATIONS FOR NURSING

With its significant impact on quality of life, peripheral neuropathy treatment and prevention are important components in the care of patients with cancer.

Peripheral neuropathy and cancer

Peripheral neuropathy has a major impact on quality of life and may limit the amount of treatment patients can receive. Neurotoxic agents are used increasingly in oncologic practice, yet clinicians are often unaware of the protean manifestations of neuropathy and find its management troubling. Recent knowledge about the mechanisms of neuropathic disease and new treatments may help to minimize the impact of neuropathy on this vulnerable patient population.

Paraneoplastic syndromes of the spinal cord, nerve, and muscle

Cancer can affect the peripheral nervous system by non-metastatic, sometimes immune-mediated mechanisms. Recognition of these paraneoplastic syndromes is important because it can lead to the detection of the tumor, and also helps to avoid unnecessary studies to determine the cause of the neurologic symptoms in patients with cancer. Many paraneoplastic syndromes of the peripheral nervous system are not associated with serum antibodies that serve as markers of paraneoplasia. For this group of disorders the diagnosis depends on the clinician's index of suspicion and conventional electrophysiologic and laboratory tests. Treatment of the tumor, immunotherapy, or both may improve some of these syndromes. This review focuses on paraneoplastic syndromes of the spinal cord, peripheral nerve, and muscle.

Neuromuscular disorders in systemic malignancy and its treatment

Neuromuscular dysfunction in patients with known or suspected malignancy has three basic etiologies: (1) a direct effect of the neoplasm, either by compression or infiltration; (2) a "remote," or paraneoplastic, effect of cancer; or (3) a side effect of anticancer treatment, radiation or chemotherapy. A variety of clinical features or syndromes are due to damage either at the level of the neuron (anterior horn cell or dorsal root ganglion neuron), nerve root(s), brachial or lumbosacral plexus, peripheral nerve (motor, sensory, and/or autonomic), neuromuscular junction, or muscle. A complex clinical picture evolves when dysfunction in due to more than one cause at more than one anatomical site.

Phase II clinical trial of didemnin B in previously treated small cell lung cancer

Didemnin B (NSC 325319), a cyclic depsipeptide isolated from a Carribean sea tunicate, exhibited potent antitumor activity in preclinical studies. After determining the maximum tolerated dose in our previous phase I/II trial, we conducted a phase II study of this drug in patients with previously treated small cell lung cancer; the starting dose was 6.3 mg/m2 intravenously over 30 min every 28 days. The major side effects were in the neuromuscular system and included severe muscle weakness, myopathy and/or myotonia by electromyography, and elevation of creatine phosphokinase and aldolase levels. We also observed modest increases in bilirubin and alkaline phosphatase levels. There were minimal hematologic toxic effects. No response was observed among 15 evaluable patients, leading us to conclude that didemnin B was toxic but inactive in patients with previously treated small cell lung cancer at the stated dose and schedule. A review of the literature revealed no significant antitumor activity in cancers of the colon, breast, ovaries, cervix, or lung (non-small cell) or in renal cell carcinoma. Further clinical trials for didemnin B may not be warranted at the stated dose and schedule.

Paraneoplastic syndrome in the course of Hodgkin disease. Case report

A woman with Hodgkin disease presented a neoplastic syndrome of unusual magnitude affecting both the CNS and PNS. The severity of the clinical pattern contrasted strongly with the paucity of neuropathological findings. The report is followed by a brief discussion of the etiological and clinical problems of paraneoplastic syndromes affecting the nervous system.

Lambert-Eaton myasthenic syndrome: the lack of short-term in vitro effects of serum factors on neuromuscular transmission

Serum was obtained from 7 patients with the Lambert-Eaton myasthenic syndrome (LES), 3 patients with small-cell carcinoma of the lung (SCCL), and 9 healthy control subjects. Serum samples were applied in vitro to the rat neuromuscular junction (for 1-3 h for control LES sera; 4 h for SCCL sera), following which the pre- and postjunctional physiological effects of serum factors were studied in the presence of 10 mM [Mg2+]o. All sera produced a marked reduction in the frequency of spontaneous miniature end-plate potentials (MEPPs), while causing slight to moderate changes in MEPP amplitude. There were no consistent changes in the quantum content of the impulse-evoked end-plate potentials, though the serum from one LES patient significantly and reversibly inhibited the evoked quantal release. No significant effect was found when a human intercostal muscle was exposed to serum from another LES patient for 2 h. Therefore, when applied in vitro on a short-term basis, the putative LES autoantibodies do not consistently react with voltage-dependent calcium channels in the motor nerve terminal and thus fail to reproduce the physiologic abnormality of the syndrome. We suggest that the pathogenic IgG molecules may require more than 3h of incubation in order to gain access to, and inhibit the function of, the prejunctional Ca2+ channels.

Peripheral neuropathy associated with malignant neoplasms in dogs

Common peroneal and ulnar nerves of 21 dogs between 2 and 15 years of age with malignant tumors were examined for possible paraneoplastic effects. Percent of abnormalities in single-teased fiber studies exceeded the confidence limits (P = 0.99) established for age-matched control dogs in 16 of 21 dogs (76%) with malignancies, none of which manifested clinical signs of polyneuropathy. The incidence of abnormalities was higher in common peroneal nerve (73%) than in ulnar nerve (57%). Lesions were characterized by a mixture of demyelination/remyelination and axonal degeneration; however, the former lesions predominated in most affected dogs. The severity of the neuropathy varied with different tumors, with the most severe lesions observed in a bronchogenic carcinoma (59%), a mammary adenocarcinoma (59%), a malignant melanoma (48%), and an insulinoma (47%).

Passively transferred Lambert-Eaton syndrome in mice receiving purified IgG

Purified IgG antibodies were prepared by ion-exchange chromatography from the plasma of a patient with nonneoplastic form of the Lambert-Eaton myasthenic syndrome (LES). The antibodies were injected into mice with daily doses of 0.15-10 mg for 20-22 days, following which the integrity of neuromuscular transmission was assessed in vitro in phrenic nerve-diaphragm muscle preparations. The injected animals manifested electrophysiologic features of human LES, which were characterized by: dose-dependent reduction in the quantal content of nerve-evoked endplate potentials, an abnormally small increase in the frequency of spontaneous miniature endplate potentials (MEPPs) with elevated [K+]o, and normal MEPP amplitude with no evidence of postjunctional deficiency. Crude immunoglobulins (Igs) from the same patient and two LES patients with associated malignancy similarly transferred the defects in quantal transmitter release. In contrast, animals receiving Igs from control subjects or from a patient with small-cell carcinoma of the lung manifested no functional impairment of neuromuscular transmission. Instead, the evoked release in these animals was significantly enhanced relative to that found in normal untreated mice. These results suggest that an IgG antibody produces the presynaptic impairment that is characteristic of LES and support the concept that LES with and without cancer has an autoimmune pathogenesis.

Mixed carcinomatous neuropathy in patients with lung cancer and lymphoma

A clinical, electrophysiological and histological study of the peripheral nerve was performed on 62 patients with lung cancer and 30 patients with lymphoma. There was a mild peripheral neuropathy (MPN) in 17.7% of patients with lung cancer and in 10% of those with lymphoma. MPN was related to the degree of weight loss. Histological studies of 5 patients with MPN demonstrated a loss of large myelinated fibers in all patients, axonal degeneration in 2 and remyelination in 3 patients. Electromyographic and histological findings indicate a primary axonal neuropathy with remyelination, probably secondary to axonal damage. 2 patients with lymphoma developed a severe neuropathy that remitted in 1 patient. The main pathological abnormality was segmental demyelination in both cases. Immunofluorescence studies were negative in all cases with mild or severe neuropathy.

The carcinomatous neuromyopathy of oat cell lung cancer

A prospective controlled clinical-neurophysiological-pathological study of 71 patients with oat cell carcinoma of the lung revealed no increased incidence of peripheral neuropathy at the initial stages of illness. All patients developed neuropathy by the time they had lost 15% of their body weight, but the neuropathy was less severe than in 20 age-matched alcoholic patients with an equal degree of weight loss. The weight loss and peripheral neuropathy progressed with atrophy of type II (adenosine triphosphatase-positive) muscle fibers out of proportion to the patient's loss of body weight. By 40% body weight loss, all the patients had moderate symmetrical peripheral neuropathy, 6 had proximal brachial or lumbosacral plexus metastases, and 9 had distal pressure palsies. Mononeuritis multiplex developed in only 1 patient, who had diabetes mellitus. Two patients developed Eaton-Lambert syndrome, which resolved in 1 when chemotherapy controlled the systemic tumor, with no protein in the tumor postmortem which could produce the characteristic electromyographic findings of the syndrome.