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Abstract Details

Cutaneous Silent Periods in Patients with Early-Stage ALS
Neuromuscular and Clinical Neurophysiology (EMG)
P6 - Poster Session 6 (12:00 PM-1:00 PM)
1-011

The cutaneous silent period (CSP) is an electrophysiological response equivalent to the spinal withdrawal reflex. It is mediated by inhibitory circuits at the spinal cord. Previous studies have shown that patients with amyotrophic lateral sclerosis (ALS) have abnormalities in the balance of excitation vs. inhibition of spinal and cortical motor neurons. The CSP can characterize spinal cord inhibitory responses in patients with ALS

 To determine whether Cutaneous silent periods can be elicited in patients with early-stage ALS and to characterize  the associated  electrophysiological features.

Responses were evaluated in 23 patients with early-stage ALS (age: 59.38±10 years old) and 15 controls (age: 62.18±10 years old). EMG activity was recorded from the thenar muscles while the subjects performed a mild voluntary contraction. CSP were induced with electrical stimulation, delivered to the middle finger, with three levels of intensity of electrical stimulation (25mA, 50mA, 75mA). The onset latency and the total duration of CSP responses were quantified and compared across groups and levels of intensity of stimulation. 

All subjects with ALS displayed identifiable CSP responses at high intensities of stimulation (75-100 mA). The CSP duration was increased in ALS patients, as compared to normal controls, for all levels of stimulation (25mA: 62.1±24.0 vs. 37.2 ±7.1, p= 0.000, 50mA: 73.3±33.9 vs. 44.4±7.6, p= 0.003, 75mA: 88.1± 42.7 vs. 45.7±6.6, p= 0.000). ALS patients showed similar CSP onset latencies to controls. 

The increased CSP duration observed in the ALS patients suggests increased inhibition of spinal motor neurons. A reduced number of spinal motor neurons could contribute to these fundings . CSP could be a useful probe to explore the balance between inhibition and excitability of spinal motorneurons. 

Authors/Disclosures
Joel Gutierrez, MD (Cuban Institute of Neurology & Neurosurgery)
PRESENTER
No disclosure on file
Rachel Perez-Lalana No disclosure on file
Tatiana Zaldivar Vaillant, MD No disclosure on file
Gloria Lara-Ferandez No disclosure on file
Astrubal Arias No disclosure on file
Yodeisy Ferrer No disclosure on file
Orla Hardiman, MD, FRCP, FAAN (Trinity Biomedical Sciences Institute) Dr. Hardiman has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Wave Pharmaceuticals. Dr. Hardiman has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Cytokinetics . Dr. Hardiman has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Hardiman has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Taylor and Francis. The institution of Dr. Hardiman has received research support from Science Foundation Ireland. The institution of Dr. Hardiman has received research support from HRB.