Abstract Details

Title Myotonic Discharges Help Detect Clinically Unsuspected Myotonic Dystrophy, Type 2

Topic Clinical Neurophysiology

Presentation(s) P02 - (-)

Poster/Presentation
Number 222

Objective

Background BACKGROUND: Patients with DM2 often do not have clinical evidence of myotonia and present with proximal weakness and pain. When the physical examination is unremarkable, the diagnosis may not be considered. Detection of myotonic discharges on EMG prompts further evaluation leading to diagnosis.

Design/Methods DESIGN/METHODS: The Mayo Clinic Arizona EMG Laboratory database was searched from 1993 - 2012 for diagnostic codes associated with myotonic discharges or myotonic dystrophy. Medical records were retrospectively reviewed for clinical information.

Results RESULTS: Of 43 patients identified with the above diagnostic codes, 6 (14%) were not felt to have a myotonic disorder on the basis of clinical information and were ultimately diagnosed with DM2. Demographics revealed 3 males, 3 females and an average age of 65.8 years. Most patients (67%) reported weakness with no objective strength deficit on clinical exam. Other symptoms included pain, numbness, restless leg syndrome and gait difficulty. The average time from onset of symptoms to diagnosis was 6.4 years. All 6 patients had profuse myotonic discharges on EMG. Three patients (50%) were initially misdiagnosed with fibrillation potentials or increased insertional activity on EMG. All 6 patients were eventually diagnosed with DM2 with 4 of them genetically confirmed.

Conclusions CONCLUSIONS: 1. Patients with DM2 may present without specific symptoms or physical signs. 2. Delay in diagnosis is common in these patients. 3. EMG evidence of myotonic discharges facilitates the diagnosis of DM2. 4. Early diagnosis may improve education, reduce evaluations, and provide the opportunity for therapy.

Authors/Disclosures
Alex Hlubocky, MD (NeuroDiagnostic Laboratories) PRESENTER	No disclosure on file
Mark A. Ross, MD, FAAN (Specialty Care)	No disclosure on file
Per Soelberg Sorensen	No disclosure on file

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