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Abnormalities of cortical stimulation strength-duration time constant in amyotrophic lateral sclerosis.
Pavey, Nathan A; Menon, Parvathi; Peterchev, Angel V; Kiernan, Matthew C; Vucic, Steve.
Affiliation
  • Pavey NA; Brain and Nerve Research Centre, Concord Clinical School, University of Sydney, Concord Hospital, Sydney, Australia.
  • Menon P; Brain and Nerve Research Centre, Concord Clinical School, University of Sydney, Concord Hospital, Sydney, Australia.
  • Peterchev AV; Department of Biological Sciences, Dartmouth College, Hanover, NH, USA; Department of Biomedical Engineering, Duke University, Durham, NC, USA; Department of Psychiatry and Behavioural Sciences, Duke University, Durham, NC, USA; Department of Electrical and Computer Engineering, Duke University, Dur
  • Kiernan MC; Neuroscience Research, Australia.
  • Vucic S; Brain and Nerve Research Centre, Concord Clinical School, University of Sydney, Concord Hospital, Sydney, Australia. Electronic address: steve.vucic@sydney.edu.au.
Clin Neurophysiol ; 164: 161-167, 2024 Aug.
Article in En | MEDLINE | ID: mdl-38901111
ABSTRACT

OBJECTIVES:

Strength-duration time constant (SDTC) may now be determined for cortical motor neurones, with activity mediated by transient Na+ conductances. The present study determined whether cortical SDTC is abnormal and linked to the pathogenesis of amyotrophic lateral sclerosis.

METHODS:

Cortical SDTC and rheobase were estimated from 17 ALS patients using a controllable pulse parameter transcranial magnetic stimulation (cTMS) device. Resting motor thresholds (RMTs) were determined at pulse widths (PW) of 30, 45, 60, 90 and 120 µs and M-ratio of 0.1, using a figure-of-eight coil applied to the primary motor cortex.

RESULTS:

SDTC was significantly reduced in ALS patients (150.58 ± 9.98 µs; controls 205.94 ± 13.7 µs, P < 0.01). The reduced SDTC correlated with a rate of disease progression (Rho = -0.440, P < 0.05), ALS functional rating score (ALSFRS-R) score (Rho = 0.446, P < 0.05), and disease duration (R = 0.428, P < 0.05). The degree of change in SDTC was greater in patients with cognitive abnormalities as manifested by an abnormal total Edinburgh Cognitive ALS Screen score (140.5 ± 28.7 µs, P < 0.001) and ALS-specific subscore (141.7 ± 33.2 µs, P = 0.003).

CONCLUSIONS:

Cortical SDTC reduction was associated with a more aggressive ALS phenotype, or with more prominent cognitive impairment.

SIGNIFICANCE:

An increase in transient Na+ conductances may account for the reduction in SDTC, linked to the pathogenesis of ALS.
Subject(s)
Key words

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Evoked Potentials, Motor / Transcranial Magnetic Stimulation / Amyotrophic Lateral Sclerosis / Motor Cortex Limits: Adult / Aged / Female / Humans / Male / Middle aged Language: En Journal: Clin Neurophysiol Journal subject: NEUROLOGIA / PSICOFISIOLOGIA Year: 2024 Document type: Article Affiliation country: Country of publication:

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Evoked Potentials, Motor / Transcranial Magnetic Stimulation / Amyotrophic Lateral Sclerosis / Motor Cortex Limits: Adult / Aged / Female / Humans / Male / Middle aged Language: En Journal: Clin Neurophysiol Journal subject: NEUROLOGIA / PSICOFISIOLOGIA Year: 2024 Document type: Article Affiliation country: Country of publication: