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Published on: October 26, 2014
Large Amplitude Cortical Evoked Potentials in Nonepileptic Patients. Reviving an Old Neurophysiologic Tool to Help
Guillermo Martín-Palomeque1, Antonio Castro-Ortiz, Pilar Pamplona-Valenzuela
1*Department of Clinical Neurophysiology, Hospital Ramón y Cajal, Madrid, Spain; †Department of Clinical Neurophysiology, Hospital General Universitario de Ciudad Real, Madrid, Spain; ‡Department of Clinical Neurophysiology, Hospital Universitario de Torrejón, Madrid, Spain; and Departments of §Neurology & Neurological Sciences and ‖Neurosurgery, Stanford University School of Medicine, Stanford, California, U.S.A.
Purpose:
Although large amplitude evoked potentials (EPs) are typically associated with progressive myoclonic epilepsy patients, giant EPs imply central nervous system (CNS) hyperexcitability and can be seen in various nonepileptic disorders.
Methods:
We performed a retrospective chart review including history, physical examination, imaging and diagnostic studies of nonepileptic patients with large amplitude somatosensory evoked potentials (SSEPs) and visual evoked potentials (VEPs) during 2007 to 2013. Large amplitude EPs were defined as follows: VEPs (N75-P100) >18 μV; and SSEPs (N20-P25) >6.4 μV. Recording montage for VEPs was Oz-Cz and SSEPs C3'/C4'-Fz.
Results:
Fifty-two patients (33 females, 19 males; age range, 9-90 years) were identified. No CNS pathology was detected in 7 patients. All remaining patients were diagnosed with new CNS disorders including: vascular (37%); myelopathies (13%); demyelinating (11%); space occupying lesions (8.7%); syringomyelia (8.7%); hydrocephalus (6.5%); Vitamin B-12 deficiency (4.3%); multiple system atrophy (4.3%); and toxins (2.2%).
Conclusions:
This study supports the notion that large amplitude EP implies CNS hyperexcitability and CNS disease. These results confirm the utility of EP studies in patients with suspected CNS pathology.
