128-channel somatosensory evoked potentials in the differential diagnosis of parkinsonian disorders.
OBJECTIVE
The differential diagnosis of parkinsonian disorders can be very difficult, especially at an early stage. In this study, we investigated whether SEP amplitude recorded by 128-channel EEG is useful for diagnosis of parkinsonian disorders, and in particular whether SEP asymmetry can differentiate corticobasal degeneration (CBGD) from other parkinsonian disorders.


METHODS
We recorded median nerve SEPs in 47 patients suspected of CBGD, supranuclear palsy or definite Parkinson's disease at an early stage. We compared SEP asymmetry and parietal peak amplitudes of the patients after grouping them based on their clinical diagnosis after 1-5 years of follow-up. In nine subjects the diagnosis remained unclear.


RESULTS
Three of 13 patients with a clinical diagnosis of CBGD had an abnormal SEP asymmetry. Furthermore, we found extremely high N20 amplitudes in three other patients with CBGD. However, similar asymmetry abnormalities were found in patients with other Parkinsonian disorders.


CONCLUSIONS
Despite the use of 128-channel SEP recordings and analysis techniques, which are more accurate than conventional techniques, sensitivity and specificity of cortical median nerve SEP asymmetry and parietal amplitude for differentiating CBGD from other parkinsonian disorders were low at an early stage of the disease. A possible reason for this may be that the hand area of the primary somatosensory cortex was not yet affected in most CBGD patients.
van de Wassenberg
W J G
WJ
Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. w.j.g.van.de.wassenberg@neuro.umcg.nl
van der Hoeven
J H
JH
Leenders
K L
KL
Maurits
N M
NM
D000368:Aged; D003937:Diagnosis, Differential; D004569:Electroencephalography / Q000379:methods*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000502:physiology; D008875:Middle Aged; D020734:Parkinsonian Disorders / Q000175:diagnosis* / Q000503:physiopathology*; D011446:Prospective Studies; D012189:Retrospective Studies; D013494:Supranuclear Palsy, Progressive / Q000175:diagnosis / Q000503:physiopathology