title: [Atypical paraneoplastic myasthenic syndrome: Lambert-Eaton syndrome or myasthenia?].
abstract: We report a case of paraneoplastic myasthenic syndrome with clinical features suggesting Lambert Eaton syndrome but without the electromyographic elements required for diagnosis. Anti-calcium channel antibodies were also lacking. The electromyogram evidenced a block and the Tensilon test was positive. The efficacy of anticholinesterases argued in favor of myasthenia but anti-acetylcholine receptor antibodies were negative. The block was more of a mixed nature, involving both presynaptic transmission as in Lambert Eaton syndrome and post-synaptic transmission as in paraneoplastic myasthenia. The primary tumor was identified as a small-cell neuroendocrine lung carcinoma on mediastinal biopsies obtained directly on CT-scan guided puncture of a mediastinal node. Thoracotomy was thus avoided. The Lambert Eaton syndrome is a paraneoplastic manifestation of small-cell lung cancer in 50% of the cases unlike generalized myasthenia which apparently is never associated with small-cell lung cancer. A mixed paraneoplastic neuro-muscle junction disorder with aspects of each can be exceptionally observed.
authors.affiliation: Service de Neurologie, Hôpital Tenon, Paris.
authors.forename: J P
authors.initials: JP
authors.lastname: Ferroir
authors.forename: B
authors.initials: B
authors.lastname: Milleron
authors.forename: A
authors.initials: A
authors.lastname: Ropert
authors.forename: C
authors.initials: C
authors.lastname: Billy
authors.forename: L
authors.initials: L
authors.lastname: Nahum
authors.forename: S
authors.initials: S
authors.lastname: Tcherakian
authors.forename: M F
authors.initials: MF
authors.lastname: Carette
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use; D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001706:Biopsy; D016190:Carboplatin / Q000627:therapeutic use; D018278:Carcinoma, Neuroendocrine / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D018288:Carcinoma, Small Cell / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy; D003131:Combined Modality Therapy; D003937:Diagnosis, Differential; D005047:Etoposide / Q000627:therapeutic use; D005260:Female; D006801:Humans; D015624:Lambert-Eaton Myasthenic Syndrome / Q000175:diagnosis*; D008168:Lung / Q000473:pathology; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000175:diagnosis*; D010257:Paraneoplastic Syndromes / Q000175:diagnosis*; D011879:Radiotherapy Dosage; D014057:Tomography, X-Ray Computed
chemical_list: D000970:Antineoplastic Agents; D000972:Antineoplastic Agents, Phytogenic; D005047:Etoposide; D016190:Carboplatin