Lambert-Eaton syndrome without an identified neoplasm

Abstract

Introduction: Lambert-Eaton syndrome occurs due to the attack of autoantibodies to voltage-gated calcium channels in the presynaptic terminal of the neuromuscular junction and is usually paraneoplastic. Objectives: Describe the case of a patient with weakness which was investigated for neoplasm. Design and setting: Case report Methods: Analysis of medical record, photographic record of the diagnostic methods and literature review. Case description: Woman, 60 years old, diabetic, hypertensive and ex-smoker, with proximal weakness in the lower limbs for 4 months with paresthesia in the extremities. In 2 months she needed a cane due to frequent falls, followed by proximal weakness of the upper limbs. She lost 8 kg in 4 months. Neurological examination showed hypotrophy in thighs, proximal tetraparesis predominantly in lower limbs and global hyporeflexia. Electroneuromyography showed decreases to repetitive low-frequency stimulation, but significant increases with repetitive high-frequency stimulation and increased amplitude of compound muscle action potentials after effort, suggesting impairment of the neuromuscular junction in the presynaptic topography. She was diagnosed with LambertEaton syndrome. An investigation of paraneoplastic syndrome was carried out, with tumor markers, tomography of the chest, abdomen and pelvis, thyroid ultrasound, mammography and oncotic colposcopy, all without findings of neoplasia. It was proposed a treatment with human immunoglobulin and followup with physiotherapy, occupational therapy and psychology. She showed a significant improvement in strength after starting treatment. Conclusion: Patients with Lambert-Eaton syndrome should be investigated for an underlying neoplasm and followed up periodically, considering the possibility of cancer diagnosis even months or years after the neurological syndrome.