Paraneoplastic neurologic manifestations of neuroendocrine tumors

Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors arising from the transformation of neuroendocrine cells in several organs, most notably the gastro-entero-pancreatic system and respiratory tract. The classification was recently revised in the 5th Edition of the WHO Classification of Endocrine and Neuroendocrine Tumors. NENs can rarely spread to the central or peripheral nervous systems. Neurologic involvement is determined by the rare development of paraneoplastic syndromes, which are remote effects of cancer. Mechanisms depend on immunologic response to a tumor, leading to the immune attack on the nervous system or the production of biologically active ("functioning") substances, which can determine humoral (endocrine) effects with neurologic manifestations. Paraneoplastic neurologic syndromes (PNS) are immunologically mediated and frequently detected in small cell lung cancer but rarely seen in other forms of NEN. PNS and Merkel cell carcinoma is increasingly reported, especially with Lambert Eaton myasthenic syndrome. Endocrine manifestations are found in a wide spectrum of NENs. They can develop at any stage of the diseases and determine neurologic manifestations. Patient outcomes are influenced by tumor prognosis, neurologic complications, and the severity of endocrine effects.

Brief Communication: Lambert-Eaton Myasthenic Paraneoplastic Syndrome Associated With Merkel Cell Carcinoma Successfully Treated by Immune Checkpoint Inhibitors: 2 Cases

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine cutaneous tumor with high metastatic potential. In rare cases, it can be associated with paraneoplastic syndromes (PNS), which result from an antitumor immunity against antigens produced by the tumor itself. Lambert-Eaton Myasthenic Syndrome (LEMS) is a neurological autoimmune PNS characterized by an impairment of the neuromuscular junction, leading to proximal muscle weakness and fatigability. Although the development of immune checkpoint inhibitors (ICI) is a breakthrough in the management of many cancers, onset or worsen of immune diseases has been described. Thereby, in patients with previous neurological PNS like LEMS, the ICI therapy for cancer may aggravate neurological symptoms and lead to irreversible impairment. We report here 2 cases of patients with metastatic MCC associated with a LEMS at the diagnosis. Both successfully received ICI therapies (anti-PDL1 avelumab and anti-PD1 pembrolizumab) without worsening of LEMS and any major immune-related adverse effects. Their neurological condition improved and disappeared concomitantly with the efficacy of immunotherapy, and we did not observe relapse of both MCC and LEMS after treatment discontinuation. Finally, we performed a complete review of the literature, which confirmed that ICI treatment could be discussed for patients with paraneoplastic LEMS, and emphasized the need for multidisciplinary management.

Paraneoplastic syndromes in ophthalmology

Paraneoplastic syndromes consist on systemic manifestations associated with certain cancers which are not a direct consequence of tumor invasion or its metastases. It is known that autoimmunity and autoantibody synthesis play an important role in its pathophysiology due to a process of molecular mimicry. Paraneoplastic syndromes in ophthalmology are rare, but it is important to recognize them clinically because in some cases symptoms preceded the diagnosis of an underlying neoplasia. Most frequently involved cancer is small cell lung carcinoma, but there is also a relationship with other tumor etiologies such as thymoma, gynecological tumors or neuroblastoma in children. Paraneoplastic syndromes with ocular involvement can be divided into those that affect the afferent visual pathway, such as cancer-associated retinopathy, melanoma-associated retinopathy, or paraneoplastic optic neuropathy; and the ones that affect the efferent visual pathway, such as bilateral tonic pupils, Myasthenia Gravis, Lambert-Eaton syndrome or paraneoplastic cerebellar degeneration. The presence of autoantibodies is helpful in clinical practice but negativity does not exclude this diagnosis. Although evolution and prognosis is linked to primary disease, in some cases specific treatment, usually immunosuppressive therapy, can help improving patients quality of life.

Lambert-Eaton myasthenic syndrome and merkel cell carcinoma

Lambert-Eaton myasthenic syndrome (LEMS) is an antibody-mediated disorder of the neuromuscular junction that is most commonly diagnosed in association with small cell lung carcinoma (SCLC). Small cell lung carcinoma is histologically similar to the aggressive cutaneous neuroendocrine malignancy Merkel cell carcinoma (MCC). We provide a full report and longitudinal clinical follow-up of a case of LEMS occurring with MCC. We also review the literature on paraneoplastic syndromes associated with MCC and other nonpulmonary small cell carcinomas.

Lambert-Eaton Myasthenic Syndrome Associated with Synchronous Double Cancer: A Combination of Small Cell Carcinoma of the Cervix and Breast Carcinoma

Lambert-Eaton myasthenic syndrome (LEMS) is most commonly associated with small cell lung carcinoma, while it is rarely associated with gynecological and breast carcinoma. We herein report a case of LEMS associated with synchronous double cancer, which was a combination of small cell carcinoma of the cervix and breast carcinoma. The early diagnosis and treatment of LEMS are important for achieving a good outcome. The possibility of accompanying paraneoplastic neurological syndrome must be sufficiently considered in gynecology and breast cancer patients. To our knowledge, this is the first report of LEMS associated with synchronous double cancer.

Paraneoplastic Cerebellar Degeneration and Lambert-Eaton Myasthenic Syndrome Associated with Neuroendocrine Carcinoma of the Oropharynx

Paraneoplastic cerebellar degeneration and Lambert-Eaton myasthenic syndrome (PCD-LEMS) are usually associated with small-cell lung carcinoma (SCLC). PCD-LEMS with extrapulmonary non-SCLC tumors; however, has not been previously reported. A 78-year-old man presented with dysarthria, dysphagia, staggering gait, and lower extremity muscle fatigue. He was diagnosed with PCD-LEMS associated with neuroendocrine carcinoma of the oropharynx, based on the histological findings of the biopsy, the existence of antibodies against P/Q-type voltage-gated calcium channels, and an incremental response of the compound muscle action potentials during repetitive nerve stimulation tests. Thus, PCD-LEMS should be included in the differential diagnosis of neurological dysfunction, even in extrapulmonary non-SCLC patients.

Paraneoplastic Inverse Myasthenic Syndrome as a Presentation of Bronchogenic Carcinoma

Tumours may produce growth factors and cytokines responsible for signs and symptoms distant to the primary or metastatic site. This may be the first sign of a malignancy and its recognition may be critical for early cancer detection. Moreover, proper diagnosis spares the patient of extensive and expensive search for an alternate cause of the neurological dysfunction. In neurological paraneoplastic syndromes like Lambert Eaton Myasthenic syndrome associated with small cell lung cancer, evidence of autoimmunity against presynaptic neuro-muscular junction by anti voltage gated calcium channel anti bodies is well documented. 60% of patients with LEMS are associated with an underlying cancer, usually SCLC. We report a 49 year old male, with over thirty pack years of smoking, who presented with dysautonomia, constitutional symptoms and weakness of all four limbs. Investigations confirmed axonal motor neuropathy with limited stage SCLC with fibro nodular lesions right upper lobe and mediastinal lymphadenopathy. He improved dramatically following chemotherapy and radiotherapy.

[A case of small cell lung cancer that presented with paraneoplastic syndrome]

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.

Lambert-Eaton myasthenic syndrome in brief

Lambert-Eaton myasthenic syndrome is a rare neurological syndrome of autoimmune origin. It is usually associated with small-cell lung cancer but may be idiopathic. The main clinical feature is potentially disabling limb muscle weakness. Clinical signs of autonomic nervous system involvement are frequent. The muscle weakness often improves with physical exercise, which distinguishes this syndrome from myasthenia. Tendon reflexes are reduced or absent but reappear temporarily after brief muscle contraction. Diagnosis is confirmed by electromyographic findings. Management is generally based on treatment of the underlying malignancy. Immunosuppressants are used in severe disease and in cases not associated with cancer, but they have limited efficacy. Symptomatic treatments are available but their efficacy is poorly documented.

[Paraneoplastic cerebellar degeneration and Lambert-Eaton myasthenic syndrome associated with anti P/Q-type voltage-gated calcium channel antibody in a patient with primary double lung cancer]

We report the case of a 50-year-old man with paraneoplastic cerebellar degeneration (PCD) and Lambert-Eaton myasthenic syndrome (LEMS) associated with primary double lung cancer. He developed acute progressive double vision, slurred speech, and gait disturbance. Neurological examination revealed diplopia, mild ptosis, bilateral horizontal gaze-evoked nystagmus, and cerebellar limb and truncal ataxia. The diffusion image of brain magnetic resonance imaging (MRI) revealed no abnormal findings in the cerebellum. On the basis of the diagnosis of acute cerebelitis, he was given methylprednisolone pulse therapy followed by oral prednisolone, which gradually improved his neurological signs and symptoms. The analysis of the possible etiology suggested that the PCD was induced by lung cancer, which led to ataxia. A chest computed tomography scan revealed mass lesions of irregular shape and unclear margins in the upper lobe of the right lung and a small nodule tumor in the upper lobe of the left lung. We performed transbronchial needle aspiration and detected the bronchioloalveolar carcinoma of the right lung. An electromyogram showed waxing phenomenon in the ulnar nerve at high-frequency (50Hz) stimulation. The serum levels of anti-P/Q-type voltage-gated calcium channel (VGCC) antibody were elavated in the patient. These findings confirmed that the pathogenesis of the condition of this patient to be associated with LEMS. His cerebellar symptoms were considered to be caused by the PCD, and the diplopia, ptosis, and hyporeflexia were attributed to LEMS. We performed upper left lobectomy with mediastinal lymphnode dissection via video-assisted thoracoscopic surgery. A histological study detected small cell carcinoma. A diagnosis of double primary lung cancer was made. Physicians need to be aware that patients may develop PCD and LEMS associated with anti-VGCC antibody caused by small cell lung cancer, and a mass survey should be conducted and careful examinations performed.

[A case of Lambert-Eaton myasthenic syndrome with small cell lung cancer, treated with 3,4-diaminopyridine]

A 77-year-old man was admitted to our hospital with muscle weakness and shortness of breath. Chest CT showed a mass in the left upper lobe, and electromyography showed waxing phenomenon with high-frequency repetitive stimulation. We diagnosed Lambert-Eaton myasthenic syndrome accompanying small cell lung cancer. He was treated with carboplatin and etoposide, and concurrent thoracic irradiation. Although, the tumor size decreased, his myasthenic symptoms remained. He started taking 3,4-diaminopyridine and his muscle weakness improved dramatically, and he was eventually able to walk finally. In some cases, anti-tumor therapies cannot improve the myasthenic symptoms. In such cases, 3,4-diaminopyridine could improve the quality of life, and should be approved in Japan.

[Case of anti P/Q type VGCC antibody positive small lung cell carcinoma that occured with subacute cerebellar degeneration, Lambert-Eaton myasthenic syndrome, and brainstem encephalitis]

A 62-year-old man was admitted to our hospital because of rapidly progressive dysarthria, truncal ataxia, and gait disturbance. High titers of the ProGRP and anti-P/Q-type VGCC antibody were detected in the serum. High accumulation of [18F] was detected at the hilus of the left lung on [18F]-FDG-PET scan. A high-frequency repetitive stimulation test of the median nerve yielded an incremental response. On the basis of these findings, a diagnosis of paraneoplastic cerebellar degeneration (PCD) and Lambert-Eaton myasthenic syndrome (LEMS) associated with small cell lung carcinoma (SCLC) was diagnosed. After intravenous immunoglobulin therapy (IVIg), methylprednisolone (m-PSL) pulse therapy, and other multidisciplinary concurrent treatments, a partial regression of the SCLC and a significant improvement in neurological symptoms were observed. However, ataxia relapsed and brainstem encephalitis developed 6 months later. A marginal improvement in neurological symptoms was observed with IVIg, m-PSL pulse therapy, and intravenous cyclophosphamide pulse therapy (IVCY). SCLC also recurred later. We hypothesized that VGCC of the brainstem was damaged by anti-P/Q-type VGCC antibody.

Paraneoplastic chronic demyelinating neuropathy and Lambert-Eaton myasthenic syndrome associated with multiple anti-neural antibodies and small-cell lung cancer

Lambert-Eaton myasthenic syndrome (LEMS) developed in a patient with presumed chronic inflammatory demyelinating polyneuropathy (CIDP) and negative chest CT. Since antibodies against both Hu and voltage-gated calcium channel (VGCC) were detected, repeated chest CT was performed, which eventually showed a pulmonary mass lesion. Biopsy revealed small cell lung cancer (SCLC) indicating the importance of repeated chest CT in LEMS even when an existing autoimmune-like disease and negative CT may suggest an autoimmune origin. This is the first report of paraneoplastic CIDP and LEMS associated with anti-Hu, anti-VGCC and SCLC.

[Small cell lung cancer with Sjögren's syndrome and Lambert-Eaton myasthenic syndrome]

A 72-year-old man was admitted to our hospital with complaints of dry mouth, muscle weakness of the lower limbs and gait disturbance. The patient had dry mouth, dry eyes, positive anti-SS-B antibody and salivary gland inflammation. Sjögren's syndrome was diagnosed. Since muscle weakness of the lower limbs and gait disturbance were not compatible with Sjögren's syndrome, we considered the possibility of paraneoplastic syndrome. Serum levels of CEA, NSE and ProGRP were elevated. Chest roentgenogram and CT showed a nodular lesion in the right upper lobe of the lung and swollen lymph nodes in the hilum and mediastinum. Small cell lung cancer was diagnosed by bronchoscopy. Anti-P/Q-type Ca2+ channel antibody was positive. Electromyogram showed a reduction in the amplitude of the evoked muscle action potential response after slow repetitive stimulation and did not show a reduction after rapid repetitive stimulation. Based on these findings, we made a diagnosis of Lambert-Eaton myasthenic syndrome (LEMS). Concurrent chemoradiotherapy induced an improvement of muscle weakness of the lower limbs. LEMS is frequently associated with a malignant tumor and an autoimmune disorder. We thought that in this patient, the presentation of LEMS was apparent because he had both Sjögren's syndrome and small cell lung cancer.

Syndrome de Lambert-Eaton et neuroblastome chez l'enfant : à propos de 2 observations

Lambert-Eaton myasthenic syndrome is a paraneoplasic syndrome which can reveal a primitive tumor. Frequently, the first diagnosis is myasthenia gravis. This disease is extremely rare in children. Only 10 cases have been reported in the last 35 years. We report 2 new observations occurring in very young patients, aged 2 and 3 years, with a ganglioneurobastoma as primitive tumor.

[A case of the Lambert-Eaton syndrome of non-neoplastic origin. Ten-year follow-up]

A case is presented of a 34-year-old man who developed weakness of the proximal muscles of the extremities, particularly lower, slight myalgia, and vegetative symptoms (dryness in the mouth). Those symptoms progressed within a month. On examination weakness of the muscles of the extremities was found as well as weak tendon reflexes, slight atrophy of muscles of the arms and thighs and apokamnosis. Edrophonium test was slightly positive. Electrostimulation revealed changes typical of the Lambert-Eaton syndrome: low amplitude of the compound muscle action potential on single stimulus, decreasing amplitude of the subsequent responses to 3 Hz stimulation, marked facilitation on 30 Hz stimulation. Neoplastic etiology was excluded by chest X-ray and CT, as well as by bronchoscopy, abdominal and prostatic USG, and thyroid USG and scintigraphy. Antibodies to AChR were not found in the serum. The titre of the antibodies against voltage-gated calcium channels was highly positive which was decisive in the diagnosing of the Lambert-Eaton syndrome. The patient was treated with pyridostigmine, corticosteroids, cyclophosphamide and immunoglobulins. Ten years of follow-up have fully confirmed the diagnosis of a non-neoplastic Lambert-Eaton syndrome.

Clinical aspects of neuromuscular transmission disorders

Autoimmune disorders of neuromuscular transmission are caused by antibodies (abs) directed against membrane proteins at the motor end-plate. Myasthenia gravis (MG) is due, in most cases, to abs against the nicotinic acetylcholine receptor (AChR). Anti-AChR-positive MG actually includes different disease entities: weakness can be confined to extrinsic ocular muscles or can be generalized; patients with generalized MG (G-MG) can be subdivided on the basis of age of onset, HLA association and thymic pathology. About 15% of G-MG patients are anti-AChR-negative; in a proportion of these cases serum abs against the muscle- specific kinase (MuSK) are found. Anti-MuSK-positive MG is characterized by predominant involvement of bulbar muscles and very low frequency of thymic pathology. The Lambert-Eaton myasthenic syndrome (LEMS) is caused by abs against voltage-gated calcium channels at nerve terminal. LEMS is characterized by muscle weakness and autonomic disturbances and it is paraneoplastic in over 50% of the cases. In neuromyotonia and cramp-fasciculation syndrome, that are thought to be due to anti-voltage-gated potassium channel abs, signs of peripheral nerve hyperexcitability can be associated with CNS features.

[A case of cT0N2M0 small cell lung cancer with Lambert-Eaton myasthenic syndrome]

We encountered a very rare case of cT0N2M0 small cell lung cancer (SCLC) with Lambert-Eaton myasthenic syndrome (LEMS). A 69-year-old man with a complaint of muscle weakness was admitted to our hospital. Although his chest radiograph on admission showed no abnormal findings, CT scanning detected a mediastinal lymphadenopathy. Also, 2-[18F]-2-fluorodeoxy-D-glucose position emission tomography (FDG-PET) revealed increased accumulation in the same portion in the mediastinum. A diagnosis of LEMS was made from the distinctive electromyogram (EMG) findings (waning and waxing phenomenon in response to low-and high-frequency repetitive stimulation, respectively) in combination with the increased serum level of a P/Q-type anti-voltage-gated calcium channel (VGCC) antibody. Subsequent histopathological diagnosis by mediastinoscopic resection of a paraaortic lymph node was small cell carcinoma. No distant metastasis was detected by MRI of the brain, abdominal CT scan or an FDG-PET. Eight courses of chemotherapy (carboplatin + etoposide) with radiotherapy of the mediastinum (for a total dose of 45 Gy) was performed. A decreased serum level of P/Q-type anti-VGCC antibody titers followed by marked improvement of neurological dysfunction (muscle weakness, gait disturbance and scanning speech) and of an EMG finding (a loss of waning phenomenon) was observed. A close relationship between reduction of the antibody titers and improvement of neurological symptoms after the therapy was noticed. It was suggested that monitoring the level of a P/Q-type anti-VGCC antibody titer in the serum is important for evaluating the efficacy of chemotherapy for LEMS associated with SCLC.

Lambert-Eaton myasthenic syndrome

The Lambert-Eaton Myasthenic Syndrome (LEMS) is characterised by proximal muscle weakness initially affecting gait, autonomic symptoms (dry mouth, constipation, erectile failure), augmentation of strength during initial voluntary activation, and depressed tendon reflexes with post-tetanic potentiation. The disorder is paraneoplastic (small cell lung cancer) in about 60p. cent (P-LEMS); no cancer is associated in the remainder (NP-LEMS). LEMS affects all races. NP-LEMS can occur in childhood as well as adult life; P-LEMS is unusual at<30 Years. The weakness results from a reduction in the quantal release of acetylcholine from motor nerve terminals, caused by autoantibodies to P/Q-type voltage-gated calcium channels (VGCCs) that are provoked by tumour VGCCs in P-LEMS; the stimulus in NP-LEMS is not known. These antibodies may be implicated in the rarely associated cerebellar degeneration. The diagnosis can be confirmed by detecting the specific antibody in a radioimmunoprecipitation assay, and by finding a reduced compound muscle action potential amplitude that increases by>100p. cent following maximum voluntary activation. Most patients benefit from 3,4-diaminopyridine; pyridostigmine is less effective. Specific tumour therapy in P-LEMS will often ameliorate the neurological disorder. In those with severe weakness, IVIg or plasmapheresis confers short-term benefits. Prednisone alone or combined with azathioprine or cyclosporin can achieve long-term control of the disorder.

Imagerie des complications neurologiques du carcinome bronchique

The natural history of bronchogenic carcinoma shows that 42% of patients are diagnosed with cancer-related neurological complications either at initial presentation or at follow-up that can be separated in 3 different categories: - locoregional involvement of cervicothoracic nerves (recurrent laryngeal nerves, phrenic and vagus nerves, brachial plexus and sympathetic cervical chains), - metastatic disease characterized by intracranial lesions (brain, meningeal, ependymal and pituitary metastases) and spinal (extradural, subarachnoid and medullary metastases) lesions, - paraneoplastic syndromes including limbic encephalitis, Lambert-Eaton syndrome and paraneoplastic cerebellar degeneration. These neurological disorders usually are associated with advanced cancer for which radical surgical management seldom is indicated. All imaging studies performed at the time of initial staging for bronchogenic carcinoma should therefore be carefully reviewed in order to detect signs that could suggest the presence of one or several neurological complications. The goals of this paper are to describe the clinical signs and to illustrate the imaging features of neurological complications related to bronchogenic carcinoma at conventional radiography, CT and MRI.

Lupus-like disease with anticardiolipin antibodies and lupus anticoagulant as a cause for atypical Eaton-Lambert syndrome and peripheral nerve disease: a case report

In the practice of neurology, the type of clinical involvement suggests the site of the lesion and the mechanism beneath. Sometimes, the symptoms can be delusive, turning the diagnostic approach to a wrong path and raising the necessity of an algorithm considering the less probable entities. Dysimmunity as mechanism of neurological disease involving both the neuromuscular junction and peripheral nerves is frequently insidious and difficult to suspect on clinical basis alone. We report the case of a 67-year-old male with atypical Eaton-Lambert syndrome and mononeuropathy probably in relation with lupus-like entity. The patient has also high titers of anticardiolipin antibodies and lupus anticoagulant. We are considering the diagnostic algorithm before an isolated and atypical neurological presentation and reviewing the main neurological manifestations in lupus-like and autoimmune systemic disease. We raise the difficulty to classify an inflammatory connective tissue disease in the absence of other pathologic features than autoantibodies and isolated neurological symptoms and discussing the main therapeutic issues.

Anti-Hu paraneoplastic syndrome presenting with brainstem-cerebellar symptoms and Lambert-Eaton myasthenic syndrome

Paraneoplastic syndrome (PNS) with two distinct neurological features was reported in a 50-year-old man who presented initially with vertigo, ataxia, dysarthria, tremor, confusion, urinary retention and hypotension. Pulmonary X-ray findings, class IIIb sputum cytology, and positive anti-Hu antibody established the diagnosis of PNS associated with small-cell lung cancer (SCLC). Two cycles of combined chemotherapy resulted in shrinkage of the lung tumor together with complete recovery of neurological symptoms and disappearance of anti-Hu antibody. Relapse of SCLC 4 months later with re-appearance of anti-Hu antibody required additional chemotherapy and irradiation. Eight months later, when multiple liver metastasis of SCLC was noticed, muscular weakness with positive waxing phenomenon compatible with Lambert-Eaton myasthenic syndrome (LEMS) developed. Postmortem examinations revealed residual SCLC in the primary lung, and massive liver metastasis with generalized lymph node involvement, but no tumors in the CNS. In the cerebellum, there was a slight loss of Purkinje cells with torpedo formation but without apparent lymphocytic infiltration. The present PNS was unique in that the relapse of SCLC was accompanied by the appearance of anti-Hu antibody, and that initial signs of brainstem-cerebellar symptoms, encephalopathy and autonomic failure were replaced by LEMS coinciding with the tumor recurrence.

The immunopathogenesis of paraneoplastic neurological syndromes

Paraneoplastic neurological syndromes are rare non-metastatic complications of cancer that have an immune-mediated aetiology. The central and peripheral nervous systems are considered to be immune-privileged sites, since the presence of the 'blood-brain/nerve barrier' means that antigens sequestered within the nervous system do not normally induce an immune response. Aberrant expression of a neuronal antigen by a tumour arising outside this barrier can lead to the breakdown of immune tolerance to the nervous system. However, in many cases the immune mechanisms that result in neurological dysfunction remain poorly defined. Furthermore, aberrant expression of neuronal antigens can be detected in many tumours that are not complicated by non-metastatic neurological syndromes. This review article examines current concepts in the immunopathogenesis of paraneoplastic neurological syndromes.

[Channelopathy]

Recently, a variety of ion channel defects have been identified as the biological basis of certain familial epilepsies, paroxysmal movement disorders, myopathies and some degenerative disorders of central nervous system. Ion channel defects were mainly caused by genetic and autoimmune mechanisms. Here, we reviewed several channelopathies including spinocerebellar ataxia type 6, familial hemiplegic migraine, episodic ataxia type 2, familial hypokalemic periodic paralysis, congenital myotonia, malignant hyperthermia, epilepsy, Gitelman syndrome and Lambert-Eaton syndrome.

Paraneoplastic and metastatic neurologic complications of Merkel cell carcinoma

Merkel cell carcinoma is a rare primary cutaneous neuroendocrine tumor that is locally aggressive and frequently accompanied by distant metastases. Neurologic complications of Merkel cell carcinoma are rare. We describe a 69-year-old man who presented with Lambert-Eaton myasthenic syndrome and was found to have Merkel cell carcinoma. The paraneoplastic syndrome improved with initial treatment of the malignancy. He subsequently developed a solitary brain metastasis and died of leptomeningeal carcinomatosis.

[Proximal muscle weakness, depressed tendon reflexes and autonomic dysfunction: the Lambert-Eaton myasthenic syndrome]

Three patients with Lambert-Eaton myasthenic syndrome (LEMS), two men aged 61 and 64 and a woman aged 55 years, all developed proximal weakness, depressed tendon reflexes and autonomic dysfunction. Although this clinical triad is highly suggestive for LEMS, the disorder had not been recognized initially. The woman had a small-cell bronchial carcinoma, treated successfully by chemotherapy, whereafter the LEMS symptoms gradually disappeared. The first man was treated with 3,4-diaminopyridine and azathioprine, whereupon his symptoms diminished. The other man had only slight complaints and refused drug treatment. The three cases illustrate that presentation and course of LEMS can vary between patients. Furthermore, clinical and electrophysiological features can suggest myasthenia gravis, myopathy or axonal polyneuropathy. Therapeutic options and the risk of underlying malignancy make early diagnosis important. In conclusion, in every patient presenting with unexplained proximal weakness, LEMS should be considered, especially if depressed tendon reflexes and autonomic dysfunction are found as well.

[Paraneoplastic diseases of the motor end-plate and muscle]

INTRODUCTION

Some forms of myasthenia gravis and many cases of Eaton-Lambert syndrome are disorders of neuromuscular transmission possibly of paraneoplastic origin. Paraneoplastic necrotizing myopathy and some cases of inflammatory myopathy (polymyositis-dermatomyositis) are paraneoplastic myopathies.

DEVELOPMENT

These are all autoimmune processes. The diagnosis is clinical, based mainly on the characteristics of the muscle weakness and motor disorders, confirmed by serological methods (demonstration of antibodies) pharmacological and electromyographic tests, by imaging studies and in some cases biopsy. Treatment includes specific symptomatic measures (aimed at correcting the defect in neuromuscular transmission in the myasthenic syndromes, reducing axonal auto-excitability in the neuromuscular hyperexcitability syndromes, etc.) and pathogenic treatment (basically immunosuppression). A search for the hidden tumour should also be part of the diagnostic investigation. The paraneoplastic disease may remit if the associated tumour is treated.

[Paraneoplastic cerebral syndromes with oto-neuro-ophthalomologic manifestations]

OBJECTIVE

To review the paraneoplastic neurologic syndromes associated with otoneurophthalmologic manifestations.

DEVELOPMENT

Paraneoplastic otoneurophthalmologic syndromes usually result from encephalitis of the brainstem and/or cerebellar degeneration. They can develop in association with various immunological responses against onconeuronal proteins (e.g. anti-Hu, anti-Ri, anti-Yo, anti-Ma, anti-Ta and anti-Tr) or with immunological mechanisms against unknown antigens. The eye movement abnormalities may have a supranuclear, nuclear or internuclear origin. There is no ocular movement abnormality which can be considered pathognomonic of a paraneoplastic disorder, but opsoclonus-myoclonus of infancy is often associated with neuroblastoma. The association of hearing loss and paraneoplastic sensory neuronopathy suggests that in some patients the neurosensory deafness result from involvement of the ganglia of Corti and/or the cochlear nuclei in the brain stem. The management of these syndromes depends on their rapid identification as paraneoplastic disorders and on the early diagnosis and treatment of the cancer. Patients with anti-Ta (or anti Ma-2) antibodies may improve with treatment of the cancer, usually a germ-cell tumor of the testis. Paraneoplastic opsoclonus-myoclonus of infancy usually improves with treatment that combines chemotherapy, steroids, and intravenous immunoglobulins, although neurological sequelae (psychomotor and language retardation) are frequent.

CONCLUSIONS

There are several paraneoplastic neurologic syndromes that may present with otoneurophthalmologic symptoms. Detection of antineuronal antibodies facilitates the early identification of some of these syndromes and associated tumors. In general, the management of these syndromes is based on treatment of the associated cancer.

[Paraneoplastic syndromes in otoneuro-ophthalmology]

INTRODUCTION AND OBJECTIVE

The so-called neurological paraneoplastic syndromes (NPNS) are a group of diseases of the central nervous system of unknown etiology which are seen almost exclusively in patients with cancer. We review the main NPNS paying particular attention to those with ophthalmological and otological features.

DEVELOPMENT

Certain neuro-ophthalmological findings may constitute, at least partly, some paraneoplastic syndromes. There are alterations of vision in paraneoplastic retinopathy and in optic neuritis of paraneoplastic origin. The latter, unlike the retinopathy, usually coexists with involvement of other structures of the nervous system. Oculomotor function is affected in the opsoclonus-myoclonus syndrome. Diplopia and/or ophthalmoplegia may be a predominant or initial symptom, in patients with paraneoplastic neurological degeneration or brainstem encephalitis. In the Lambert-Eaton syndrome and in paraneoplastic encephalomyelitis, may have blurred vision and alterations of the pupil. Cases of paraneoplastic uveitis have also been described. Paraneoplastic otological involvement is less frequent. Patients with sensorineural deafness in the context of a paraneoplastic encephalomyelitis have been reported. In the NPNS vertigo is caused by cerebellar or brainstem lesions and not by lesions of peripheral organs. When nystagmus occurs in a NPNS it may be of various types and is due to involvement of structures in the brain stem or cerebellum.

CONCLUSIONS

The diagnosis of NPNS in patients with no known cancer is important because it may lead to the detection of an occult cancer which is localized or scarcely extended, and therefore is still potentially treatable. Oto-neuro-ophthalmological manifestations may be the first or only symptom of presentation of a paraneoplastic neurological clinical picture.

[Pathology of paraneoplastic syndromes of the central and peripheral nervous systems and muscle ]

INTRODUCTION AND DEVELOPMENT

The paraneoplastic neurological syndromes are alterations associated with neoplasias. However, they are not caused by metastases or complications such as infections, vascular disorders, metabolic or nutritional alterations or secondary effect of treatment. The paraneoplastic syndromes are often associated with the creation of autoantibodies against antigens produced by the neoplastia, but also may be against other cells or target molecules of the patient. Sometimes, especially with antibodies directed against cell membrane proteins, there is a close relationship between the antibody and the target organ, as for example antibodies against the acetylcholine receptor in myasthenia gravis. On other occasions, especially when the antigen is intracellular, the mechanism of the autoantibody reaction is not known. Finally, in a third group, the antibody associated with a particular paraneoplastic neurological alteration has not been identified. In this paper we describe the main paraneoplastic neurological pictures and known antibodies, including the molecular aspects and the neoplasias most frequently related to them.

[A Lambert-Faton myasthenic syndrome and subacute cerebellar degeneration with a favorable clinical course after resection of small-cell lung cancer]

A case of Lambert-Eaton myasthenic syndrome (LEMS) and subacute cerebellar degeneration (SCD) was associated with small-cell lung cancer (SCLC). The patient, a 52-year-old man, who had noticed impotence one year previously, began to have ataxic gait, scanning speech and thirst progressing for 3 months, followed by weakness of the lower limbs, bilateral blepharoptosis, and double vision. Electromyographic studies showed low amplitude of compound muscle action potential (CMAP) and waxing phenomenon in high frequency stimulation of the ulnar nerve. A chest x-ray showed a mass lesion in the left hilar region, and small cell lung cancer was diagnosed on the basis of biopsy specimens. Anti-voltage-gated calcium channel (VGCC) antibody was positive. Anti-Yo and anti-Hu antibodies were negative. The patient was treated by lobectomy and chemotherapy, which resulted in improvement in the LEMS and SCD. Anti-VGCC antibody, the CMAP amplitude, and waxing phenomenon were improved. Operable cases of SCLC are rare. But we propose that anti-neoplastic treatment including resection of the tumor is the first choice for the treatment of paraneoplastic syndrome associated with SCLC.

Humoral immunity against glutamic acid decarboxylase and tyrosine phosphatase IA-2 in Lambert-Eaton myasthenic syndrome

Some beta-cell-specific autoantigens also are present in the central nervous system. Furthermore, stiff man syndrome, an autoimmune neurological disease, is frequently associated with diabetes and shares with this one an anti-GAD and IA-2 humoral immunoreactivity. We wondered whether these autoantibodies could be found in other neurological diseases with a present or supposed autoimmune origin. So, anti-GAD65 (GAD65A) and anti-IA-2 (IA-2A) autoantibodies were assayed in various neurological diseases. There was a higher prevalence of such antibodies in Lambert-Eaton myasthenic syndrome (LEMS) (GAD65A, 35%; IA-2A, 21%; double positivity, 18%) compared to amyotrophic lateral sclerosis (18%, 12%, and 12%, respectively) and multiple sclerosis (10%, 3%, and 3%, respectively). In LEMS, the humoral reaction was more frequent and/or appeared earlier in the paraneoplastic forms. The detection of such autoantibodies in patients with small-cell lung carcinoma (SCLC) without LEMS suggests that these autoantigens, GAD65 and IA-2, could be produced by SCLC tissue.

Poorly differentiated carcinoma of the lung presenting with Lambert--Eaton myasthenic syndrome

Lambert-Eaton myasthenic syndrome commonly seen in small-cell lung cancer represents an autoimmune reaction against antigens coexpressed by tumor and neurons. It is rarely seen with other histologic subtypes. Symptoms antedate the appearance of the neoplasm by weeks to years. Therapeutic options range from immunosuppression, plasmapheresis, pharmacologic facilitation of neuromuscular transmission, and definitive therapy of the primary tumor. This case report describes the rare association of Lambert-Eaton myasthenic syndrome with non-small-cell lung cancer.

[Small cell lung cancer associated with paraneoplastic cerebellar degeneration and Lambert-Eaton myasthenic syndrome]

A 57-year-old man was admitted to our hospital in November 1997 because of dysarthria, progressive ataxia, generalized weakness, and incoordination in both hands. He had been aware of the dysarthria 6 months earlier. Chest roentgenograms and computed tomographic films disclosed a 5 cm x 6 cm mass in the left S3b. The patient was given a diagnosis of small cell lung cancer (T3N2M0, stage IIIA) associated with paraneoplastic cerebellar degeneration (PCD). Three courses of chemotherapy (carboplatin and etoposide) eliminated the tumor and slightly alleviated the PCD symptoms. In March 1998, electromyograms revealed a fall in the single-stimulated M wave and a waxing phenomenon that had not been observed on admission. Anti-P/Q type voltage gated calcium channel antibody was detected in serum samples obtained on admission and after chemotherapy. These findings confirmed an association with Lambert-Eaton myasthenic syndrome. No relapse of the tumor has been observed 15 months after the last course of chemotherapy.