Multiple System Atrophy Presenting as Motor Neuron Disease (P6.069)

Objective: To study MSA patients initially diagnosed with motor neuron disease and determine whether this influences the diagnosis and course of MSA. Background: The presence of upper and lower motor neuron signs in multiple system atrophy (MSA) has been noted since Shy and Drager highlighted spasticity and fasciculations in their early description; however, the presence of motor neuron disease may lead to misdiagnosis of MSA. Design/Methods: All patients diagnosed with MSA at Mayo Clinic, Rochester with autonomic function testing between 1998 and 2012 were retrospectively reviewed. Patients presenting with an initial referring diagnosis of motor neuron disease were compared to those with other initial diagnoses. Results: From 685 MSA patients, 8 were initially diagnosed as amyotrophic lateral sclerosis, primary lateral sclerosis, or as motor neuron disease. Six of the patients were ultimately diagnosed with MSA-parkinsonism, 2 with MSA-cerebellar ataxia. Autopsy was performed in 2 patients, confirming MSA. Onset of symptoms was motor in 6 patients including leg weakness, falls, dysarthria, and dysphagia. Seven patients had an EMG; 2 demonstrated fibrillation and/or fasciculation potentials while 1 had cramp discharges. The mean time from symptom onset to diagnosis for those initially diagnosed with motor neuron disease was 2.97 years compared to 4.148 years in all MSA patients ( p = 0.0765). In patients with an initial motor neuron disease diagnosis, those with EMG findings had a mean time to MSA diagnosis of 4.11 years compared to 2.28 with normal EMGs ( p = 0.0773). Overall survival for patients with an initial diagnosis of motor neuron disease was 4.67 years compared 7.61 years in all other MSA patients ( p = 0.0101). Conclusions: Our findings suggest that MSA patients may initially present with subtle findings of motor neuron disease. Overall, the few patients presenting with an initial diagnosis of motor neuron disease had shorter survival. Disclosure: Dr. Jones has nothing to disclose. Dr. Nelson has nothing to disclose. Dr. Bower has nothing to disclose. Dr. Matsumoto has nothing to disclose. Dr. Sandroni has nothing to disclose. Dr. Benarroch has nothing to disclose. Dr. Suarez has nothing to disclose. Dr. Low has nothing to disclose. Dr. Singer has nothing to disclose. Dr. Coon has nothing to disclose.