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Poster 65: Navigated Transcranial Magnetic Stimulation is More Sensitive Than Nonnavigated in Obtaining Upper Extremity Motor Evoked Potentials for Low Functioning Stroke Patients

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      Objective: Using transcranial magnetic stimulation (TMS), to compare motor evoked potentials (MEPs) produced by navigated brain stimulation (NBS) versus non-NBS in chronic stroke patients. Design: Cross-sectional, randomized design. Setting: Outpatient rehabilitation hospital. Participants: 34 subjects >6 months poststroke in the middle cerebral artery territory exhibiting stable arm hemiparesis. Interventions: A brain magnetic resonance imaging was obtained within 2 weeks of TMS. The Action Research Arm Test (ARAT), NBS, and non-NBS MEPs were obtained on the same day by separate, blinded testers. The sequence (NBS vs non-NBS) was randomized for each subject. MEPs were obtained for the contralesional abductor pollicis brevis, abductor digiti minimi, extensor digitorum communis, and biceps brachii. Main Outcome Measures: ARAT, MEPs. Results: 15 subjects (45.7%) were low functioning (ARAT=0) and the remaining 19 subjects had a median ARAT of 22 (range, 1–60). NBS detected MEPs for 24 muscles in 11 of the 15 low functioning subjects. Non-NBS detected MEPs for 16 muscles in 9 of these 15 subjects. Among the 15 low functioning subjects, 5 (31.3%) exhibited absent MEPs with NBS and non-NBS; 6 subjects (37.5%) showed MEPs using both NBS and non-NBS; 5 subjects (31.3%) showed MEPs using NBS but not with non-NBS. No subjects exhibited MEPs using non-NBS but not with NBS. When non-NBS failed, MEPs were more likely demonstrated by NBS in the low functioning group than the high functioning group (31.3% vs 0%, P=.0135 using a Fisher exact test). Conclusions: NBS obtained MEPs in more muscles of lower-functioning subjects compared to non-NBS. This may be due to the greater precision of the NBS system. NBS may be able to better predict functional recovery after stroke.