Abstract Details

Title The Clinical Spectrum of Lower Motor Neuron Syndrome

Topic Anterior Horn

Presentation(s) P03 - (-)

Poster/Presentation
Number 047

Objective

Background BACKGROUND: Lower motor neuron (LMN) syndromes present a unique challenge to clinicians because of a diverse differential diagnosis, broad range of prognoses, and frequent diagnostic uncertainty. Previous studies have highlighted the frequency of diagnostic errors in motor neuron disease (MND) and in multifocal motor neuropathy (MMN). In this study, we catalogued the entire spectrum of diagnoses seen in patients presenting with undifferentiated LMN syndromes.

Design/Methods DESIGN/METHODS: We conducted a systematic search of clinic and billing records to identify adults with muscle weakness, atrophy, or fasciculations, but without upper motor neuron signs or sensory involvement. We analyzed history, examination, electrodiagnostic, and laboratory data retrospectively over 11 years.

Results RESULTS: Out of 1800 charts reviewed we found 128 subjects meeting criteria for LMN syndrome. Fifty two percent of these did not have MND. Of those without MND, 23% had immune neuropathies and 19% had genetic conditions, including spinal muscular atrophy and Kennedy disease. The remainder had infections, benign fasciculations, myopathies, or remained undiagnosed. Bulbar and respiratory symptoms were common in MND and virtually excluded immune neuropathies. Only MND had cognitive dysfunction or frontal release signs. In MMN only 43% had anti-ganglioside antibodies, and only 54% had conduction block (CB) on electrodiagnostic studies. One subject had neither autoantibodies nor CB, but responded well to IVIG. Over half of subjects with immune neuropathies improved in objective muscle strength over time.

Conclusions CONCLUSIONS: Most patients with pure LMN syndrome do not have MND and surprisingly high numbers have treatable conditions which respond to therapy. Cognitive involvement, frontal release signs, and bulbar or respiratory symptoms are strongly suggestive of MND. Electrodiagnostic testing and serology may fail to identify patients with MMN, raising the question of whether patients with undifferentiated LMN syndrome should receive an empiric trial of IVIG.

Authors/Disclosures
Alan Sanderson, MD (Intermountain Cedar City Clinic) PRESENTER	No disclosure on file
William D. Arnold, MD	Dr. Arnold has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Arnold has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for La Hoffmann Roche. Dr. Arnold has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Cadent Therapeutics . Dr. Arnold has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. The institution of Dr. Arnold has received research support from NIH. The institution of Dr. Arnold has received research support from NMD Pharma. The institution of Dr. Arnold has received research support from Gilead Sciences. The institution of Dr. Arnold has received research support from CureSMA. Dr. Arnold has received intellectual property interests from a discovery or technology relating to health care.
Bakri Elsheikh, MD, FAAN (The Ohio State University Wexner Medical Center)	Dr. Elsheikh has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biogen . Dr. Elsheikh has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Argnex . The institution of Dr. Elsheikh has received research support from Biogen. The institution of Dr. Elsheikh has received research support from Cure SMA.
John T. Kissel, MD, FAAN	Dr. Kissel has nothing to disclose.
	No disclosure on file
Brian Harel, PhD	Brian Harel, PhD has received personal compensation for serving as an employee of Takeda. An immediate family member of Brian Harel, PhD has received personal compensation for serving as an employee of Astra Zeneca. Brian Harel, PhD has or had stock in Takeda, Merck, Day One Biopharmaceuticals. An immediate family member of Brian Harel, PhD has or had stock in Eli Lilly, Pfizer, Astra Zeneca.Brian Harel, PhD has or had stock in Cogstate.

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