Evoked Potentials

Evoked Potentials are a crucial tool for neurologists, as they allow for the observation of the central nervous system’s integrity with greater sensitivity than clinical assessments alone.

In some cases, evoked potentials may be altered even in patients who exhibit no symptoms or whose MRI results are normal, making them an important diagnostic and monitoring tool for many conditions, particularly multiple sclerosis.

There are several types of evoked potentials:

• Visual Evoked Potentials (VEP) These measure the electrical impulses generated by the retina and transmitted to the brain, enabling vision. Specifically, visual evoked potentials are the bioelectrical variations in the occipital cortex triggered by visual stimuli. They reflect the complex neurosensory processes involved in transducing and transmitting visual nerve impulses from the retinal photoreceptors, through the optic nerve, and up to the occipital cerebral cortex. Testing visual evoked potentials is highly useful in diagnosing and differentiating between various visual pathologies of interest to both ophthalmologists and neurologists. It also plays a role in the diagnosis of many other chronic degenerative diseases, such as multiple sclerosis.

• Auditory Evoked Potentials Also known as ABR (Auditory Brainstem Response), this is a neurological test that assesses brainstem function in response to auditory stimuli. The test is conducted by recording an electrical nerve potential evoked by a sound transmitted through headphones, which tracks the impulses from the inner ear to the auditory cortex.

• Somatosensory or Tactile Evoked Potentials These record the electrical impulses generated by stimulation of nerves in the hands or feet, transmitted along the spinal cord to the sensory cortex, where these signals are processed, enabling the sensation of touch.

• Motor Evoked Potentials (MEP) Used to assess the functionality of the motor nervous system, these measure the muscle responses triggered by electrical or magnetic stimulation of the cerebral cortex or spinal cord. MEPs allow for the study of the pathway that carries stimuli from the motor cortex, through the spinal cord, to the motor neurons and muscles.