Abstract
The diagnosis of amyotrophic lateral sclerosis (ALS) relies on identification of a combination of upper (UMN) and lower motor neuron (LMN) signs. The current ALS diagnostic criteria formulated at Awaji attempts to improve the diagnostic sensitivity by incorporating neurophysiological measures of LMN dysfunction, though assessment of UMN dysfunction remains clinically based. Given that cortical hyperexcitability appears to be an early feature in ALS, the present study assessed the diagnostic utility of threshold tracking transcranial magnetic stimulation (TMS) technique as an aid to the Awaji criteria in establishing of an earlier diagnosis of ALS. Studies were undertaken prospectively on a cohort of 82 patients (52 men and 30 women, mean age 60 years) with suspected ALS. Paired pulse threshold tracking TMS studies were undertaken along with clinical and conventional neurophysiological examination and results were compared to 34 healthy controls (17 men, 17 women, mean age 56 years). At time of TMS testing, 61% of patients were classified as “possible” and 39% as ”probable/definite” ALS by the Awaji diagnostic criteria. Short-interval intracortical inhibition (SICI) was significantly reduced in ALS patients ( p AWAJI POSSIBLE 1.3 ± 1.3%; SICI AWAJI PROBABLE/DEFINITE 1.4 ± 1.7%). Central motor conduction time was significantly prolonged ( p p p
Published Version
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