Motor conduction measurement in myelopathy hand

Area of Science:

• Neurology
• Neurosurgery
• Radiology

Background:

• Cervical spondylotic myelopathy (CSM) is a degenerative condition affecting the cervical spinal cord.
• Intramedullary high signal intensity (IMHSI) on T2-weighted MRI can indicate spinal cord injury.
• The relationship between IMHSI and motor pathway dysfunction in CSM requires further elucidation.

Purpose of the Study:

• To investigate the correlation between intramedullary high signal intensity (IMHSI) on T2-weighted MRI and motor conduction abnormalities in patients with cervical spondylotic myelopathy (CSM).
• To determine if IMHSI impacts specific motor pathways, particularly those controlling hand function.

Main Methods:

• Utilized T2-weighted magnetic resonance imaging (MRI) to identify intramedullary high signal intensity (IMHSI) in CSM patients.
• Assessed central motor conduction times (CMCTs) for biceps, triceps, and abductor pollicis brevis muscles using transcranial magnetic stimulation.
• Compared CMCTs between patients with and without IMHSI.

Main Results:

• No significant difference in biceps or triceps CMCTs was observed between patients with and without IMHSI.
• Abductor pollicis brevis CMCT was significantly prolonged in patients exhibiting IMHSI compared to those without (p<0.05).
• This indicates that motor fibers innervating the hand are more vulnerable to damage in CSM.

Conclusions:

• Intramedullary high signal intensity (IMHSI) on MRI is associated with impaired motor conduction in the hand intrinsic muscles of CSM patients.
• The abductor pollicis brevis CMCT serves as a sensitive indicator of cervical spinal cord damage severity in CSM.
• Hand dysfunction, termed "myelopathy hand," is a characteristic impairment in CSM, reflecting the sensitivity of long motor tracts controlling hand muscles.