Exploring brainstem function in multiple sclerosis by combining brainstem reflexes, evoked potentials, clinical and...

Area of Science:

• Neuroscience
• Clinical Neurology
• Neurophysiology

Background:

• Multiple Sclerosis (MS) is a demyelinating disease affecting the central nervous system.
• Brainstem dysfunction is common in MS but can be subclinical.
• Early detection of brainstem impairment is crucial for MS management.

Purpose of the Study:

• To investigate vestibulo-masseteric (VMR), acoustic-masseteric (AMR), vestibulo-collic (VCR), and trigemino-collic (TCR) reflexes in MS patients.
• To correlate brainstem reflex (BSR) abnormalities with multimodal evoked potentials (EPs), clinical findings, and MRI.
• To assess the diagnostic performance of a combined BSR battery for brainstem dysfunction in MS.

Main Methods:

• Recording of click-evoked VMR, AMR, and VCR from masseter and sternocleidomastoid muscles.
• Recording of TCR from sternocleidomastoid muscles following infraorbital nerve stimulation.
• Standard techniques for multimodal evoked potentials (EPs) and Magnetic Resonance Imaging (MRI).

Main Results:

• High frequencies of abnormal BSRs were observed: VMR (62.1%), AMR (55.1%), VCR (25.9%), TCR (58.6%).
• A four-BSR battery identified brainstem dysfunction in 86.9% of cases, surpassing EPs (82.7%), MRI (71.7%), and clinical examination (37.7%).
• Combined BSRs/EPs demonstrated significantly higher sensitivity (93.3%) than MRI/clinical testing (70%) in early MS (disease duration ≤6.4 years).

Conclusions:

• The four-BSR battery enhances the performance of standard EPs for early brainstem impairment detection in MS.
• BSR assessment usefully supplements conventional testing for monitoring brainstem function in MS, particularly in newly diagnosed patients.
• This approach can detect brainstem impairment not evident through clinical examination or neuroimaging alone.