Efficacy of intravenous immunoglobulin for treatment of Lambert–Eaton myasthenic syndrome without anti-presynaptic P/Q-type voltage-gated calcium channel antibodies: A case report

Paraneoplastic syndrome in neuroophthalmology

Paraneoplastic syndrome is a group of clinical symptoms that occur in the state of systemic malignant tumors. Paraneoplastic syndrome of the nervous system can affect any part of the central and peripheral nervous system and may also affect the eyes. In neuroophthalmology, paraneoplastic syndrome has a variety of manifestations that can affect both the afferent and efferent visual systems. The afferent system may involve the optic nerve, retina and uvea; the efferent system may involve eye movement, neuromuscular joints or involuntary eye movements and pupil abnormalities and may also have other neurological symptoms outside the visual system. This article discusses the clinical manifestations, pathological mechanisms, detection methods and treatment methods of paraneoplastic syndrome in neuroophthalmology. The performance of paraneoplastic syndrome is diverse, the diagnosis is difficult, and the treatment should be considered systematically. Differential diagnosis, optimal evaluation and management of these manifestations is not only the key to treatment but also a challenge.

Presynaptic Paraneoplastic Disorders of the Neuromuscular Junction: An Update

The neuromuscular junction (NMJ) is the target of a variety of immune-mediated disorders, usually classified as presynaptic and postsynaptic, according to the site of the antigenic target and consequently of the neuromuscular transmission alteration. Although less common than the classical autoimmune postsynaptic myasthenia gravis, presynaptic disorders are important to recognize due to the frequent association with cancer. Lambert Eaton myasthenic syndrome is due to a presynaptic failure to release acetylcholine, caused by antibodies to the presynaptic voltage-gated calcium channels. Acquired neuromyotonia is a condition characterized by nerve hyperexcitability often due to the presence of antibodies against proteins associated with voltage-gated potassium channels. This review will focus on the recent developments in the autoimmune presynaptic disorders of the NMJ.

Autoimmune Channelopathies at Neuromuscular Junction

The neuromuscular junction, also called myoneural junction, is a site of chemical communication between a nerve fiber and a muscle cell. There are many types of channels at neuromuscular junction that play indispensable roles in neuromuscular signal transmission, such as voltage-gated calcium channels and voltage-gated potassium channels on presynaptic membrane, and acetylcholine receptors on post-synaptic membrane. Over the last two decades, our understanding of the role that autoantibodies play in neuromuscular junction disorders has been greatly improved. Antibodies against these channels cause a heterogeneous group of diseases, such as Lambert-Eaton syndrome, Isaacs' syndrome and myasthenia gravis. Lambert-Eaton syndrome is characterized by late onset of fatigue, skeletal muscle weakness, and autonomic symptoms. Patients with Isaacs' syndrome demonstrate muscle cramps and fasciculation. Myasthenia gravis is the most common autoimmune neuromuscular junction channelopathy characterized by fluctuation of muscle weakness. All these disorders have a high risk of tumor. Although these channelopathies share some common features, they differ for clinical features, antibodies profile, neurophysiological features, and treatments. The purpose of this review is to give a comprehensive insight on recent advances in autoimmune channelopathies at the neuromuscular junction.