Spontaneous electromyographic activity in spinal cord lesions

Area of Science:

• Neuroscience
• Neurology
• Clinical Electrophysiology

Background:

• Electromyography (EMG) is crucial for diagnosing neuromuscular disorders.
• Spinal cord diseases can manifest with diverse and complex EMG findings.
• Understanding spontaneous EMG activity aids in localizing spinal cord lesions.

Purpose of the Study:

• To characterize specific spontaneous EMG activities observed in spinal cord diseases.
• To investigate the association between lesion type and observed EMG phenomena.
• To explore the underlying pathophysiological mechanisms of these abnormal discharges.

Main Methods:

• Review of electromyographic (EMG) examination findings in patients with spinal cord diseases.
• Correlation of specific spontaneous EMG activities with diagnoses such as syringomyelia and intramedullary tumors.
• Analysis of the potential role of inhibitory pathway dysfunction and motor neuron excitability.

Main Results:

• Continuous motor unit activity, synchronous motor unit potentials, myokymic discharges, segmental and propriospinal myoclonus, and respiratory synkinesis are observed.
• These specific discharges are more prevalent in syringomyelia and intramedullary tumors compared to other spinal cord lesions.
• Findings suggest a link between central spinal cord lesions and the emergence of abnormal spontaneous EMG activity.

Conclusions:

• Central spinal cord lesions, particularly syringomyelia and intramedullary tumors, are associated with characteristic spontaneous EMG activities.
• The derangement of inhibitory mechanisms within the spinal cord likely contributes to these abnormal discharges.
• Increased excitability of spinal motor neurons is proposed as a fundamental underlying mechanism.