098 A case of myasthenia gravis lambert eaton overlap syndrome (MLOS) in seronegative myasthenia gravis. Issue 6 (24th May 2018)

• Record Type: Journal Article
• Authors: Saleem, Sameer; Patel, Ronak; Gawarikar, Yash
• Is Part Of: Journal of neurology, neurosurgery and psychiatry. Volume 89:Issue 6(2018)
• Page Start: A39
• Page End: A39
• Publication Date: 2018-05-24
• Subjects: Neurology -- Periodicals; Nervous system -- Surgery -- Periodicals; Psychiatry -- Periodicals; 616.8
• DOI: 10.1136/jnnp-2018-ANZAN.97
• Languages: English
• ISSNs: 0022-3050

Abstract

Abstract : Introduction: Myasthenia gravis (MG) is an antibody-mediated autoimmune disease of neuromuscular transmission. 6 to 12 percent of MG are negative for acetyl choline receptor (AChR) and MuSK antibodies and are defined as seronegative MG. Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune condition with antibodies to presynaptic voltage-dependent calcium channel Case: A 39 year old male presented with blurred vision and right-sided ptosis. Initial examination showed a pupil-sparing left complete third nerve palsy. Demyelination and intracranial aneurysms were ruled out with gadolinium-enhanced MRI/MRA. Outpatient follow-up 2 weeks later showed new onset proximal muscle weakness of the upper limbs with fatigability and a complex ophthalmoplegia with almost complete paralysis of gaze. A repeat MRI with gadolinium and CSF analysis were normal. His AChR and MuSK antibodies were negative; however, voltage-dependent calcium channel antibodies, ANA, dsDNA, and SSA were positive. Initial nerve conduction tests were normal, but repeat NCS on two separate occasions showed decrement on repetitive stimulation in the right trapezius with no evidence of facilitation post exercise. CT chest, abdomen and pelvis was normal. He improved with pulsed steroids and was discharged on a tapering dose of oral steroids, pyridostigmine and regular IVIG infusions as a steroid-sparing agent. Conclusion: Lambert-Eaton myasthenic syndrome shares the same pathologic site and similar pathophysiology with MG but has a markedly different clinical and electro-physiological picture. There are reports of MG and LEMS overlap syndrome, however, they exhibit phenotypic characteristics of both LEMS and MG. Voltage-dependent calcium channel antibodies have not been described in patients with seronegative MG. Ours is potentially the first reported case of seronegative myasthenia with voltage-dependent calcium channel antibodies and only clinical and neurophysiological features of MG.