Evoked Potential Examination

Neurophysiology

Evoked potential examination provides an effective objective assessment of the visual system (VEP, ERG, EOG) auditory and brain stem system (AEP) peripheral and central nervous system (MSSEP, LSSEP).

The minimum time is 45 minutes but can last up to 2 hours depending upon the investigation requested and modalities required.

The stimulus given may be a visual image, such as the movement of a checkerboard pattern on a TV screen, or a sound through headphones or a small electrical pulse to the skin. The choice of these is made depending on the type of symptoms

VEP and ERG may be used to evaluate many problems/disorders including, but not limited to, the following:

• Pigmentary retinal dystrophy
• Cone dystrophy
• Vascular lesions
• Macular disease
• Glaucoma
• Optic nerve disease
• On organic visual loss

SSEP are particularly useful for the evaluation in three circumstances:

• Measure peripheral conduction velocities when sensory nerve action potentials cannot be obtained at the periphery
• Exploration of proximal lesions of the peripheral sensory pathways not accessible to conventional EMG studies
• Study of the whole somatosensory pathway up to the cortex in any pathology combining peripheral and central lesions

Go to the Neurophysiology overview page