Lambert-Eaton myasthenic syndrome (LEMS) is an uncommon disorder of neuromuscular transmission with distinctive pathophysiological, clinical, electrophysiological and laboratory features. There are two forms of LEMS. The paraneoplastic (P-LEMS) form is associated with a malignant tumor that is most frequently a small cell lung carcinoma (SCLC), and the autoimmune (A-LEMS) form is often related to other dysimmune diseases. Approximately 90% of LEMS patients present antibodies against presynaptic membrane P/Q-type voltage-gated calcium channels (VGCC). These antibodies are directly implicated in the pathophysiology of the disorder, provoke reduced acetylcholine (ACh) at the nerve terminal and consequently lead to muscle weakness. LEMS is clinically characterized by proximal muscle weakness, autonomic dysfunction and areflexia. In clinically suspected cases, diagnoses are confirmed by serological and electrodiagnostic tests. The detection of P/Q-type VGCC antibodies is supportive when there is clinical suspicion but should be carefully interpreted in the absence of characteristic clinical or electrodiagnostic features. Typical electrodiagnostic findings (ie, reduced compound motor action potentials (CMAPs), significant decrements in the responses to low frequency stimulation and incremental responses after brief exercise or high-frequency stimulation) reflect the existence of a presynaptic transmission defect and are key confirmatory criteria. Diagnosis requires a high level of awareness and necessitates the initiation of a prompt screening and surveillance process to detect and treat malignant tumors. In clinically affected patients without cancer and after cancer treatment, symptomatic treatment with 3,4-diaminopyridine or immunosuppressive agents can significantly improve neurologic symptoms and the quality of life. We present a detailed review of LEMS with special emphasis on the pathophysiological mechanisms, clinical manifestation and diagnostic procedure.

Heroin-related myelopathy is an uncommon but often devastating complication of heroin intake. It is usually reported in individuals exposed to intravenous heroin after a variable drug-free period, leading to acute and complete spinal cord injury with poor long-term outcome. We describe an original case of acute longitudinally extensive transverse myelopathy following single heroin and cocaine intravenous exposure after a long period of abstinence confirmed by toxicological hair and retrospective urine drug analysis. This case could provide new insights in the understanding of this rare neurological complication.

We suggest that differential finger extension weakness is a feature that may be seen in MMN, even in the absence of CB or response to IVIg. Muscle Nerve 55: 433-437, 2017.

Dropped head syndrome (DHS) is an uncommon clinical syndrome, which requires complex diagnostic evaluation. A variety of neuromuscular and neurodegenerative disease can produce weakness of head extensor muscles and consequently lead to head drop. Inflammatory myopathy has been described as a cause of DHS, however head drop has only exceptionally been reported as being the presenting symptom of this disorder. We describe an original case of DHS as an initial and predominant manifestation of inflammatory myopathy with histopathological features of polymyositis, with an excellent response to immunosuppressive treatment.

Susac syndrome (SS) is an autoimmune microangiopathy that affects the brain, retina, and inner ear, causing a wide range of clinical manifestations. The triad of encephalopathy, visual disturbances, and hearing loss constitute the classic disease presentation.We describe an original clinical case of a young male with a definitive diagnosis of SS, who presented with disordered behavior and amnesia, initially manifested as a dissociative or anxiety disorder but with a fulminant evolution toward severe encephalopathy associated with retinal infarcts and sensorineural hearing loss.After the diagnosis of SS, aggressive immunosuppressive treatment was started with significant neurological improvement and favorable evolution during the follow-up period. SS is a rare but potentially devastating disease that can cause great disability if not properly diagnosed and treated. The onset of SS with behavioral or psychiatric manifestation can be misleading, causing a diagnostic delay.