Lambert-Eaton Myasthenic Syndrome and Botulism

Shruti M. Raja, MD Muscle and Neuromuscular Junction Disorders p. 1596-1614 December 2022, Vol.28, No.6 doi: 10.1212/CON.0000000000001205
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PURPOSE OF REVIEW This article reviews the pathophysiology, epidemiology, clinical features, diagnosis, and treatment of Lambert-Eaton myasthenic syndrome (LEMS) and botulism, presynaptic disorders of neuromuscular transmission in which rapid diagnosis improves long-term outcomes.

RECENT FINDINGS Therapy for LEMS has seen significant advances in recent years due to the approval of amifampridine-based compounds. LEMS is likely still underdiagnosed, particularly when no underlying malignancy is identified. Clinicians must have a strong suspicion for LEMS in any patient presenting with proximal weakness and autonomic dysfunction. Botulism is another rare disorder of presynaptic neuromuscular transmission that is most commonly associated with improper storage or preservation of food products. Over the past 2 decades, wound botulism has been increasingly reported among users of black tar heroin. A high degree of clinical suspicion and electrodiagnostic studies can be beneficial in distinguishing botulism from other acute neurologic disorders, and early involvement of state and federal health authorities may assist in confirming the diagnosis and obtaining treatment. When botulism is suspected, electrodiagnostic studies can provide clinical evidence of disordered neuromuscular transmission in advance of serologic confirmation, and providers should not wait for confirmation of the diagnosis to initiate treatment.

SUMMARY A targeted clinical history and a thorough neurologic examination with support from serologic and electrodiagnostic studies are key to early diagnosis of LEMS and botulism. Early diagnosis of both conditions creates opportunities for therapy and improves outcomes.

Address correspondence to Dr Shruti M. Raja, Duke University Medical Center, 40 Duke Medicine Cir, Durham, NC 27710, [email protected].

RELATIONSHIP DISCLOSURE: Dr Raja has received personal compensation in the range of $500 to $4999 for serving as a consultant for Regeneron Pharmaceuticals and Signant Health. The institution of Dr Raja has received research support from the American Brain Foundation/Myasthenia Gravis Foundation of America.

UNLABELED USE OF PRODUCTS/INVESTIGATIONAL USE DISCLOSURE: Dr Raja discusses the unlabeled/investigational use of immunomodulatory and immunosuppressant therapies for the treatment of Lambert-Eaton myasthenic syndrome and monoclonal antibodies for the treatment of botulism.

© 2022 American Academy of Neurology.