Rinsho Shinkeigaku. 2011 Nov; 51(11): 872-6
Motomura M

The neuromuscular junction lacks the protection of the blood-nerve barrier and is vulnerable to antibody-mediated disorders. Myasthenia gravis (MG) is caused by the failure of neuromuscular transmission mediated by autoantibodies against acetylcholine receptors (AChR) and muscle-specific receptor tyrosine kinase (MuSK)/LDL-receptor related protein 4 which are AChR-associated transmembrane post-synaptic proteins involved in AChR aggregation. The seropositivity rates for AChR positive and MuSK positive MG in Japan are 80-85% and 5-10%/less than 1%,respectively. The incidence of late-onset MG, defined as onset after age 50 years, has been increasing worldwide. A nationwide epidemiological survey in Japan also revealed that the rates of late-onset MG had increased from 20% in 1987 to 42% in 2006. In 2010, a guideline for standard treatments of late-onset MG was published by the Japanese Society of Neurological Therapeutics. Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disease of the neuromuscular junction and approximately 60% of LEMS patients have a tumor, mostly small cell lung cancer (SCLC), as a paraneoplastic neurological syndrome. The clinical pictures of Japanese LEMS patients are as follows; male dominant sex ratio (3 : 1), mean age 62 years (17-80 years), 61% of LEMS have SCLC, and the remaining are without cancer. In less than 10% of cases there are signs of cerebellar dysfunctions (paraneoplastic cerebellar degeneration with LEMS; PCD-LEMS) as well, often associated with SCLC. Most patients benefit from 3, 4-diaminopyridine plus pyridostigmine. In paraneoplastic LEMS, treatment of the tumor often results in neurological improvement. In non-paraneoplastic LEMS, prednisone alone or combined with immunosuppressants are treatment options. In both MG and LEMS, where weakness is severe, plasma exchange or intravenous immunoglobulin treatment may provide short-term benefit.

Handb Clin Neurol. 2012; 105: 781-803
Grisold W, Vass A

Neuromuscular complications are common in patients with cancer. Their occurrence depends on several factors, such as the type of malignancy, tumor type, time course of the malignancy, and different types of treatment, such as surgery, radiotherapy, chemotherapy, or combinations of these. Miscellaneous other conditions, such as metabolic, paraneoplastic, and infectious causes of neuromuscular dysfunction, occur. In addition, tumor cachexia is important, with loss of muscle mass a frequent sign in cancer. The peripheral nervous system consists of cranial nerves, nerve roots, the nerve plexus, peripheral nerves (either as focal mononeuropathies or polyneuropathies), neuromuscular transmission, and muscle. Conventionally, motor neuron disease and variants are also considered in this context. The distribution of symptoms and signs varies. Focal and asymmetrical symptoms and signs point to a focal lesion, which may be caused by the tumor or its metastases, and also by treatment such as surgery or radiotherapy. The most common distribution is bilateral and symmetrical, as in neuropathies and myopathies, and most neuromuscular transmission disorders. Pain is often caused by lesions of the neuromuscular system, and can be a localizing sign; pain strategies against neuropathic pain are needed. The neurologist seeing patients with neuromuscular symptoms in a neuro-oncological setting has several roles: the precise localization of the focal lesion of the peripheral nervous system, the extent of tumor burden on the peripheral nervous system, and, sometimes, the initial detection of a tumor in paraneoplastic syndromes. If patients develop symptoms during treatment, estimation of the extent of neurotoxicity, which can be a dose-limiting factor for chemotherapy and also some biological medications, is an issue. Cranial nerve symptoms and signs, occurring either alone or multiple, are frequent in oncology patients. Peripheral nerve lesions occur at several sites inside the skull, at their exit from the skull, and in the neck or thorax region. Nerve roots are frequently affected in patients with cancer. In the majority, this is due to vertebral column metastasis, less often by meningeal involvement. The cervical and brachial plexi are the sites of local metastasis or infiltration from adjacent tumors such as lung cancer, breast cancer, or lymphoma. Local recurrence of tumors, less frequently sequelae of radiotherapy, can cause dysfunction of the sacral plexus, whereas the lumbar plexus is less frequently involved. Individual peripheral nerves can be damaged at several sites. The most frequent type of lesion is therapy related (surgery, pressure, malpositioning); neoplastic, toxic, and other causes are rare. Several types of polyneuropathy exist: paraneoplastic neuropathies can appear before the onset of cancer or may lead to the detection of cancer. The most frequent types of neuropathy in patients with cancer are chemotherapy-induced neuropathies, which may be a dose-limiting factor for treatment. Other causes of neuropathy, such as metabolic derangements, infections, or direct neoplastic involvements, are infrequent. Myasthenia gravis can be considered to be a paraneoplastic syndrome for thymoma only. Lambert-Eaton myasthenic syndrome is a presynaptic disorder affecting the cholinergic motor and autonomic synapses. About half of the cases are paraneoplastic, most frequently associated with small-cell lung cancer. Myopathies occur at various stages of tumor disease. They may be the presenting sign of a tumor disease like inflammatory myopathies, such as dermatomyositis or polymyositis, or appear during tumor treatment, such as metabolic or toxic myopathy, or in the late stages of cancer, such as cachexia. In clinical practice, direct involvement of the peripheral nervous system by cancer is as important as systemic effects on the peripheral nerve structures. For some conditions, such as tumor cachexia, neuropathies in advanced cancer, or in terminally ill patients, similar mechanisms can be suspected, which also occur in severe systemic non-neoplastic diseases such as chronic infections; a common pathway of pathogenesis can be suspected.

Brain. 2011 Dec; 134(Pt 12): 3755-74
Vincent A

John Newsom-Davis was born in 1932 and died, aged 74, in 2007. After national service in the Royal Air Force, he read Natural Sciences at Cambridge. Following clinical studies at the Middlesex Hospital, he began research into respiratory neurophysiology with Tom Sears at the National Hospital, Queen Square, in London, and spent 1 year with Fred Plum at Cornell University in New York. After neurology specialist training at Queen Square, he became the director of the Batten Unit, continuing his interest in respiratory physiology. There he began to work on myasthenia gravis in collaboration with Ricardo Miledi at University College London and in 1978, after performing the first studies on plasma exchange in that disease, he established a myasthenia gravis research group at the Royal Free Hospital. There he investigated the role of the thymus in this disease and demonstrated an autoimmune basis for the Lambert Eaton myasthenic syndrome and 'seronegative' myasthenia. He was awarded the first Medical Research Council Clinical Research Professorship in 1979 but moved to Oxford in 1987 when he was elected Action Research Professor of Neurology. While at Oxford, he continued to run a very successful multidisciplinary group, researched further into the thymic abnormalities and cellular immunology of myasthenia, identified antibody-mediated mechanisms in acquired neuromyotonia, and began the molecular work that identified the genetic basis for many forms of congenital myasthenic syndrome. Meanwhile, he was also involved in university and college governance and contributed widely to the Medical Research Council, government committees, research charities and the Association of British Neurologists. Among many honours, he was elected Fellow of the Royal Society in 1991, appointed Commander of the British Empire in 1996 and made a Foreign Associate Member of the Institute of Medicine of the United States in 2001. Nearing and following retirement from Oxford, where he continued to see patients with myasthenia, he was the President of the Association of British Neurologists and Editor of Brain, and led a National Institutes of Health-funded international trial of thymectomy.

Lancet Neurol. 2011 Dec; 10(12): 1098-107
Titulaer MJ, Lang B, Verschuuren JJ

Lambert-Eaton myasthenic syndrome (LEMS) is a neuromuscular autoimmune disease that has served as a model for autoimmunity and tumour immunology. In LEMS, the characteristic muscle weakness is thought to be caused by pathogenic autoantibodies directed against voltage-gated calcium channels (VGCC) present on the presynaptic nerve terminal. Half of patients with LEMS have an associated tumour, small-cell lung carcinoma (SCLC), which also expresses functional VGCC. Knowledge of this association led to the discovery of a wide range of paraneoplastic and non-tumour-related neurological disorders of the peripheral and central nervous systems. Detailed clinical studies have improved our diagnostic skills and knowledge of the pathophysiological mechanisms and association of LEMS with SCLC, and have helped with the development of a protocol for early tumour detection.

Rev Med Interne. 2011 Dec; 32(12): 742-50
Michaud M, Delrieu J, Astudillo L

Autoimmune channelopathies are rare neuromuscular diseases that have been characterized clinically for several decades but for which the evidence of associated antibodies has only been recently demonstrated. Ion channels have an important role of activation, inhibition and regulation in neuromuscular transmission. Myasthenia gravis, generally associated with the presence of anti-acetylcholine receptor antibody, is the best-known channelopathy. Other anti-channel antibodies, including voltage-dependent, are associated with several neurological diseases, as illustrated by anti-voltage-gated calcium channels found in Lambert-Eaton myasthenic syndrome and paraneoplastic cerebellar ataxia, and anti-voltage-gated potassium channels found in neuromyotonia, Morvan's syndrome and limbic encephalitis. The treatment of autoimmune channelopathies is logically based on corticosteroids, immunosuppressant drugs, intravenous immunoglobulins and plasmapheresis.

Support Care Cancer. 2012 Feb; 20(2): 425-8
Badari A, Farolino D, Nasser E, Mehboob S, Crossland D

Paraneoplastic neurologic syndromes (PNS) are uncommon, affecting fewer than 1 in 10,000 patients with cancer. PNS, while rare, can cause significant morbidity and impose enormous socio-economic costs, besides severely affecting quality of life. PNS can involve any part of the nervous system and can present as limbic encephalitis, subacute cerebellar ataxias, opsoclonus-myoclonus, retinopathies, chronic intestinal pseudo-obstruction (CIPO), sensory neuronopathy, Lambert-Eaton myasthenic syndrome, stiff-person syndrome, and encephalomyelitis. The standard of care for CIPO includes the use of promotility and anti-secretory agents and the resection of the non-functioning gut segment; all of which can cause significant compromise in the quality of life. There is significant evidence that paraneoplastic neurologic syndromes are associated with antibodies directed against certain nerve antigens. We successfully treated a patient with CIPO in the setting of small cell lung cancer with a combination of rituximab and cyclophosphamide. The patient, who had failed to respond to prokinetic agents, anti-secretory therapy, and multiple resections, responded to the immunomodulatory therapy, with minimal residuals with PEG tube feeding and sustained ostomy output. The use of rituximab and cyclophosphamide should therefore be considered in patients with CIPO, especially if it can avoid complicated surgical procedures.

Autoimmune Dis. 2011; 2011: 973808
Gilhus NE

Lambert-Eaton Myasthenic Syndrome (LEMS) is a rare disease with a well-characterized pathogenesis. In 50% of the patients, LEMS is a paraneoplastic manifestation and caused by a small cell lung carcinoma (SCLC). Both LEMS patients with SCLC and those without this tumour have in 85% of cases pathogenetic antibodies of very high LEMS specificity against voltage-gated calcium channels (VGCCs) in the cell membrane of the presynaptic motor nerve terminal. Better understanding of LEMS pathogenesis has lead to targeted symptomatic therapy aimed at the neuromuscular junction and to semispecific immuno-suppression. For SCLC LEMS, tumour therapy is essential.

Mol Pharmacol. 2011 Dec; 80(6): 1085-95
Kalia J, Swartz KJ

Guanidine and its alkyl analogs stimulate the neuromuscular junction presynaptically by inhibiting voltage-gated potassium (Kv) channels, leading to enhanced release of acetylcholine in the synaptic cleft. This stimulatory effect of guanidine underlies its use in the therapy for the neuromuscular diseases myasthenic syndrome of Lambert-Eaton and botulism. The therapeutic use of guanidine is limited, however, because of side effects that accompany its administration. Therefore, the design of guanidine analogs with improved therapeutic indices is desirable. Progress toward this goal is hindered by the lack of knowledge of the mechanism by which these molecules inhibit Kv channels. Here we examine an array of possible mechanisms, including charge screening, disruption of the protein-lipid interfaces, direct interaction with the voltage sensors, and pore-binding. Our results demonstrate that guanidines bind within the intracellular pore of the channel and perturb a hydrophobic subunit interface to stabilize a closed state of the channel. This mechanism provides a foundation for the design of guanidine analogs for the therapeutic intervention of neuromuscular diseases.

Nihon Kokyuki Gakkai Zasshi. 2011 Jul; 49(7): 517-22
Wakatsuki M, Matsuo K, Kayatani H, Fujiwara K, Yonei T, Sato T

A 65-year-old man had suffered from systemic erythema from November 2008 and had noticed gradually progressing weakness in the upper and lower limbs. He received medical treatment in another hospital but his symptoms did not improve. He was admitted to our hospital for treatment of diabetes in June 2009, and his chest X-ray images and CT scans showed a mass shadow in the right upper lobe with hilar and mediastinal lymphadenopathy. We performed bronchoscopy, and diagnosed small cell lung cancer (T2N2M1, stage IV). However, he had hand grip weakness and continuing upper and lower limb muscle weakness, and therefore electromyography was performed, which showed the presence of waxing in the right leg. Subsequently, a diagnosis of Lambert-Eaton myasthenic syndrome was made. As he also showed ataxia of the left lower extremity, we also diagnosed paraneoplastic cerebellar degeneration. We gave the patient chemotherapy consisting of carboplatin and etoposide which resulted in the disappearance of his waxing, and his grip strength and erythema immediately improved with regression of the tumor after 1 course of chemotherapy. We report a case of small cell lung cancer associated with Lambert-Eaton myasthenic syndrome, paraneoplastic cerebellar degeneration and erythema which presented as paraneoplastic syndrome, which improved with chemotherapy.

Neuropsychiatr Dis Treat. 2011; 7: 341-9
Lindquist S, Stangel M

In Lambert-Eaton myasthenic syndrome (LEMS), antibodies against presynaptic voltage-gated calcium channels reduce the quantal release of acetylcholine, causing muscle weakness and autonomic dysfunction. More than half of the affected patients have associated small cell lung cancer, and thorough screening for an underlying malignancy is crucial. The mainstay of treatment for LEMS is symptomatic but immunotherapy is needed in more severely affected patients. Symptomatic therapies aim at increasing the concentration of acetylcholine at the muscle endplate. While acetylcholinesterase inhibitors were the first drugs to be used for the amelioration of symptoms, 3,4-diaminopyridine (3,4-DAP, amifampridine) has been shown to be more effective. 3,4-DAP blocks presynaptic potassium channels, thereby prolonging the action potential and increasing presynaptic calcium concentrations. This then results in increased quantal release of acetylcholine. The efficacy of 3,4-DAP for increasing muscle strength and resting compound muscle action potentials has been demonstrated by four placebo-controlled trials. Side effects are usually mild, and the most frequently reported are paresthesias. The most common serious adverse events are epileptic seizures. 3,4-DAP is currently the treatment of choice in patients with Lambert-Eaton myasthenic syndrome.

Acta Neurol Scand. 2011 Jul 14;
Stich O, Klages E, Bischler P, Jarius S, Rasiah C, Voltz R, Rauer S

Stich O, Klages E, Bischler P, Jarius S, Rasiah C, Voltz R, Rauer S. SOX1 antibodies in sera from patients with paraneoplastic neurological syndromes. Acta Neurol Scand: DOI: 10.1111/j.1600-0404.2011.01572.x. © 2011 John Wiley & Sons A/S. Objectives -  SOX1 antibodies have been described in patients with Lambert-Eaton myasthenic syndrome (LEMS) in association with voltage-gated calcium channel antibodies as serological markers of small cell lung cancer (SCLC). This study was aimed to screen for additional SOX1 autoimmunity in onconeural antibody-positive sera from patients with paraneoplastic neurological syndromes (PNS) other than LEMS and to identify the clinical-immunological profile and associated tumours of patients with coexisting SOX1 antibodies. Methods- We retrospectively analysed sera from 55 patients with different PNS positive for well-characterized antineuronal antibodies for the presence of SOX1 antibodies by recombinant ELISA and immunoblot. Results- Eight (14.5%) patients showed additional SOX1 antibodies in the ELISA and the recombinant immunoblot. Five patients had coexisting Hu antibodies, while the other three showed coexisting CV2/CRMP5, amphiphysin, and coexisting CV2/CRMP5 and Hu antibodies, respectively. PNS included (partially overlapping) subacute sensory neuropathy, subacute sensorimotor neuropathy, cerebellar degeneration, brainstem encephalitis, encephalomyelitis and limbic encephalitis. No tumour was detected in two patients, while the others had lung cancer (four SCLC and two non-SCLC). One patient showed SOX1-specific intrathecal antibody synthesis. Conclusions- We describe SOX1 reactivity for the first time overlapping with CV2/CRMP5 and amphiphysin antibodies. SOX1 reactivity is predominantly associated with Hu antibodies and SCLC, but can occur also in other types of lung cancer. Neurological manifestations present in patients with coexisting SOX1 antibodies and well-characterized antineuronal antibodies do not differ from those previously described in patients positive for antineuronal antibodies but no SOX1-specific anti-glial antibodies.

Brain Nerve. 2011 Jul; 63(7): 745-54
Motomura M, Fukuda T

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disease of the neuromuscular junction, and approximately 60% of patients with LEMS have a tumor, mostly small cell lung cancer (SCLC), as a paraneoplastic neurological syndrome. The clinical data of Japanese patients in the present study are as follows: the ratio of men to women is 3: 1 (mean age, 62 years; age range, 17-80 years). Of the patients with LEMS, 61% have SCLC, whereas the others do not have cancer. Clinical symptoms are usually characterized by proximal muscle weakness and dysautonomia. In less than 10% of the patients, there are signs of cerebellar dysfunctions (paraneoplastic cerebellar degeneration with LEMS; PCD-LEMS), and these are usually associated with SCLC. The diagnosis can be confirmed by detecting a specific antibody in a radioimmunoprecipitation assay and finding reduced amplitude of compound muscle action potential that increases by over 100% after maximum voluntary activation or 50Hz of nerve stimulation. The pathomechanism of LEMS is characterized by impaired transmission across the neuromuscular junction because of autoantibodies directed against the presynaptic P/Q-type voltage-gated calcium channels (P/Q-VGCCs). Histopathologic evaluation of the cerebellum in patients with PCD-LEMS showed a reduced number of P/Q-type VGCCs in the molecular layer. Therefore, it was hypothesized that P/Q-VGCC antibodies may induce cerebellar dysfunction after entering the CNS in patients with PCD-LEMS. Specific tumor therapy in patients with LEMS as well as cancer often improves the neurologic deficit. Tumor removal is the primary treatment for LEMS. If the result of the primary screening is negative, screening should be repeated after 3-6 months and thereafter every 6 months for up to 2 years. Most patients benefit from 3, 4-diaminopyridine administered with pyridostigmine. In those with severe weakness, intravenous gamma globulin (IVIg) or plasmapheresis confers short-term benefits. Prednisone when administered alone or in combination with immunosuppressive drugs can achieve long-term control of the disorder.