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Double cortical stimulation in amyotrophic lateral sclerosis
Journal of Neurology, Neurosurgery, and Psychiatry
|December 1, 1996
Summary
Central motor tract function was assessed using transcranial magnetic stimulation in patients with amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). Findings suggest impaired intracortical inhibition in ALS patients, unlike those with SMA or healthy controls.
Area of Science:
- Neuroscience
- Neurology
- Motor System Physiology
Background:
- Amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA) are distinct motor neuron diseases.
- Understanding central motor pathway integrity is crucial for differentiating and managing these conditions.
Purpose of the Study:
- To investigate central motor tract function in ALS and SMA patients using transcranial double magnetic stimulation.
- To compare motor cortex excitability and intracortical inhibition between ALS, SMA, and healthy controls.
Main Methods:
- Transcranial double magnetic stimulation applied to the motor cortex.
- Surface electromyography (EMG) recorded from the abductor pollicis brevis (APB) muscle.
- Conditioning-test (C-T) intervals used to assess intracortical inhibition.
Main Results:
- Marked attenuation of motor evoked potentials (MEPs) observed in healthy controls and SMA patients at short C-T intervals (1-4 ms).
- Mild attenuation of MEPs in ALS patients, indicating reduced intracortical inhibition.
- Intracortical stimulus effects on the H-reflex were within normal ranges for both ALS and control groups.
Conclusions:
- The intracortical inhibitory mechanism appears to be impaired in patients with amyotrophic lateral sclerosis.
- This impairment in intracortical inhibition may serve as a distinguishing feature between ALS and SMA.