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Taking a Comprehensive Approach to Diagnosing LEMS

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On This Page INITIAL EXAM TESTING

The initial physical exam can reveal vital clues about LEMS1

A diagnosis of Lambert-Eaton myasthenic syndrome (LEMS) may be suspected based on clinical symptomatology. Ask your patients about1:

History1,2

  • LEMS not associated with cancer: Patients may have a history of autoimmune disease
  • Cancer-Associated LEMS: Patients may have a history of smoking

Signs and symptoms1

  • Muscle weakness
  • Autonomic dysfunction
  • Areflexia

LEMS and MG share certain clinical features, but these typically differ in severity and temporal pattern of symptom onset3

Most patients with myasthenia gravis (MG) have detectable antibodies, including4:

  • Acetylcholine receptor (AChR): Present in approximately 85% of generalized MG (and ~50% of ocular MG)
  • Muscle-specific kinase (MuSK): Present in approximately 5% of patients with AChR-negative MG
  • Low-density lipoprotein receptor-related protein 4 (LRP4): Present in 2%-27% of patients who test negative for AChR and MuSK

Before diagnosing seronegative MG, it is important to dig deeper and determine whether something else could be driving your patient’s symptoms.3

  • P/Q-type anti-voltage-gated calcium channel (VGCC) antibody tests can reveal LEMS in up to 90% of cases1
  • Test patients with neurologic and/or autonomic symptoms as soon as possible for anti-VGCC antibodies3,5
Test patients with symptoms of LEMS or MG as soon as possible for anti-VGCC antibodies. Approximately 10% of patients with LEMS may test negative for anti-VGCC antibodies. Electrodiagnostic testing should immediately follow to definitively rule out LEMS in these patients.1
Healthcare providers examining blood sample

Request a free blood test to confirm LEMS in your patients

In collaboration with a national diagnostic lab provider, Catalyst offers no-cost anti-VGCC antibody testing, for patients who have symptoms suggestive of LEMS.

Choose a treatment that targets the neuromuscular cause of LEMS6,7

While there is currently no cure for LEMS, effective treatments can significantly improve your patient’s sense of well-being.6,8,9

References: 1. Titulaer MJ, Lang B, Verschuuren JJ. Lambert-Eaton myasthenic syndrome: from clinical characteristics to therapeutic strategies. Lancet Neurol. 2011;10(12):1098-1107. 2. Wirtz PW, Smallegange TM, Wintzen AR, Verschuuren JJ. Differences in clinical features between the Lambert-Eaton myasthenic syndrome with and without cancer: an analysis of 227 published cases. Clin Neurol Neurosurg. 2002;104(4):359-363. 3. Merino-Ramírez MÁ, Bolton CF. Review of the diagnostic challenges of Lambert-Eaton syndrome revealed through three case reports. Can J Neurol Sci. 2016;43(5):635-647. 
4. Vinciguerra C, Bevilaqua L, Lupica A, et al. Diagnosis and management of seronegative myasthenia gravis: lights and shadows. Brain Sci. 2023;13(1286):1-13. 5. Nguyen A, Chukwuemeka A, Umeh JP. Lambert-Eaton myasthenic syndrome unmasked by administration of aggravating medications. Am J Med Case Rep. 2022;10(8):194-196. 6. Shieh P, Sharma K, Kohrman B, Oh SJ. Amifampridine phosphate (Firdapse) is effective in a confirmatory Phase 3 clinical trial in LEMS. J Clin Neuromuscul Dis. 2019;20(3):111-119. 7. Sanders DB, Juel VC, Harati Y, et al. 3,4-diaminopyridine base effectively treats the weakness of Lambert-Eaton myasthenia. Muscle Nerve. 2018;57:561-568. 8. Full Prescribing Information for FIRDAPSE (amifampridine). Catalyst Pharma; 2024. 9. Tarr TB, Wipf P, Meriney SD. Synaptic pathophysiology and treatment of Lambert-Eaton myasthenic syndrome. Mol Neurobiol. 2015;52(1):456-463.