Abstract Details

Title The Importance of Clinical Acumen in a Rare Case of Concurrent Amyotrophic Lateral Sclerosis and Myesthenia Gravis

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P5 - Poster Session 5 (5:30 PM-6:30 PM)

Poster/Presentation
Number 11-017

Objective To illustrate a case of co-occurrent amyotrophic lateral sclerosis (ALS) and myasthenia gravis (MG) and the importance of clinical judgment in interpreting serologic/electrodiagnostic testing.

Background ALS is a motor neuron disorder presenting with progressive weakness with both lower and upper motor neuron findings. MG is an autoimmune neuromuscular junction (NMJ) disorder, which presents with fatigable weakness among other features. Approximately 0.75% of ALS patients are affected by MG, indicating overlap of rare disorders. Antibody testing against acetylcholine receptors (AChR), fatigable weakness, and significant (>10%) decrement on repetitive nerve stimulation (RNS) support diagnosis of MG. Significant decrement on RNS may be seen in ALS, and up to 5% of ALS patients harbor AChR antibodies. Clinical correlation is key in appropriate diagnosis and subsequent treatment.

Design/Methods Case report and literature review.

Results An 80 year old man with 3 years of fatigable dysarthria and dysphagia was found to be AChR binding antibody positive. Pyridostigmine provided no benefit. Symptoms progression required hospitalization and treatment with 5 days of IVIG (2g/kg), and ultimate diagnosis of AChR positive MG. Over several months, he developed progressive head drop, sialorrhea, hyperreflexia, and muscle atrophy which did not respond to repeat IVIG. EMG/RNS showed diffuse, acute and chronic neurogenic changes, and >10% decrement in 2 muscles, meeting criteria for definite ALS and NMJ dysfunction. He initiated riluzole, though transitioned to hospice and died shortly after dual diagnosis.

Conclusions ALS and MG have different pathophysiology, prognosis, and treatment, despite overlap in serologic and electrodiagnostic testing. Co-occurrence is rare, though should be considered a possibility when clinical features of both are present. Our patient had MG, responsive to immunotherapy, which progressed to a phenotype more consistent with ALS. This case highlights the importance of clinical correlation to avoid misdiagnosis and to recognize rare combination of disorders, to tailor appropriate treatment regimens.

Authors/Disclosures
Katherine A. Stiles, MD (Rhode Island Hospital) PRESENTER	Dr. Stiles has nothing to disclose.
Vincent LaBarbera, MD (Brown Neurology)	Dr. LaBarbera has nothing to disclose.

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