Epikppsia, 33(5):83&840, 1992 Raven Press, Ltd., New York 0 International League Against Epilepsy

Visuomotor Coordination During Focal and Generalized EEG Discharges J. Opp, D. Wenzel, and U. Brandl Neuropediatric Department, Erlangen University Pediatric Clinic, Erlangen, Germany

Summary: A new computer-based method for continuous gauging of momentary, visuomotor coordination under simultaneous EEG control proved both effective and suitable for children. Thirty-eight patients (age 4-17 years) who had different types of hypersynchronous activity were examined: None of the patients with focal discharges showed significant impairment in the test perfor-

mance. Slight losses were evident in 3 s. Key Words: AttentionNeurologic diagnosis-ElectroencephalographyEpilepsy-Reaction time.

With EEG discharges, a reduction in brain function may occur without being detected by either the patient or doctor. Studies have concentrated on examination of reaction time (RT) (Mirsky and Van Buren, 1965; Porter et al., 1973; Browne et al., 1974; Mallin et al., 1981; Sengoku et al., 1990), or short-term memory (Jus and Jus, 1962; Aarts et al., 1984; Binnie et al., 1987; Kasteleijn-Nolst Trenite et al., 1990). Hand movement by itself, under constant visual control, is a complex brain function which is assumed to be reduced during hypersynchronous EEG activity. We devised a test in which patients were asked to chase a honey-carrying bear with a bee. The distance between the bee and the honeypot served as a measure of concentration level at that time. The experimental design was deliberately similar to computer games to facilitate examination of younger patients for a long time. We tested whether transient impairment in test performance could be detected during focal or generalized EEG discharges.

ity on one or more EEGs. Nine subjects had never had a seizure, 19 had less than one seizure a year, 10 had more than one seizure a year, and 7 had more than one seizure a week. The mental development of most of the children corresponded to their age; 11 were borderline, and 4 were retarded. Subjects were told to move the tracking object (bee) on the screen, which was under their control. The bee hunts a bear carrying honey. Steering is done with a control column (joystick) or mouse. When the attacking figure neared a bear, a noise was sounded and a bar on the right hand side of the picture would increase in size, indicating the result visually on the screen. The path along which the tracking object moved was not visible to the patient. The speed of the tracking object was adapted to the patients’ capabilities in the practice phase of the experiment. The distance between the tracking object and the attacking figure on the screen gauged the concentration capacity. The computer transmitted this measurement to a digital-analog-converter which relayed it to the EEG recording apparatus. The EEG (eight bipolar channels) was recorded by a small telemetry transmitter (Glonner Biomes 80). Data were stored by a Glonner videometric processor in digital form on VHS videocassettes and fed into the computer (IBM-PC of the AT-class) using the Brainstar program (U. Brandl, author). The experimental apparatus is shown in Fig. 1.

PATIENTS AND METHODS Thirty-eight children and adolescents aged 4-17 years participated. All had hypersynchronous activReceived August 1991; revision accepted February 1992. Address correspondence and reprint requests to Professor D. Wenzel at Neuropadiatrische Abteilung der Klinik rnit Poliklinik fur Kinder und Jungendliche der FAU. Loschgestr. IS, 8520 Erlangen, Germany.

836

83 7

VIS UOMOTOR COORDINATION AND EEG DISCHARGES

be used for further analysis. All results are combined in Table 1 . Tests lasted 29.8 ? 13.6 min (1065 min) on the average.

FIG. 1. Test conditions.

Each recording consisted of 20-s measurement, a 10-s discharge-free lead and the discharge. Recordings were then averaged by means of points (Fig. 2). The 10- to 3-s interval preceding the discharge served as a reference. We then sought alterations in the recording before, during, or after the discharge. With the Wilcoxon test for related-sample surveys, we determined whether the mean of the measurement in the interval in question differed from that in the reference interval. We did not determine patients' abilities as such, but sought only alterations in performance. Therefore, standardization of the test conditions such as duration, speed, or practice phase was not necessary. RESULTS Of the 38 participating patients, 33 showed more than four EEG discharges during our test and could Length of discharge

graphs

Separate

5s ~

--irdx,--w

,-

4 5-

,-,?-Jwp

_ - ._, ,

rJ\ __ -1-? ,'

wly\C"-.--/

'\rXYZ*ih #b-*-,-.y,!

4s 4s 4s

4s

3s

__

3..

3s

~

LL-"&,,W

3s

c-

^N--

-A

-iJ . I '

I

-

SV?

fi-.-+l--d,JiJ~rr L,.-,

d iYF._rJL.IV

Lw-,d Ld ?Llc_,,h

\r-

JL.?

"?./

-

.,r.J,-,

sLc-

?, ,

".,,,L,.,,+

Focal discharges Tracking performance was analyzed for 15 patients during sharp-wave discharges; 9 during focal spike-and-wave discharges and 3 during single spikes. An increase in measurement during discharge to more than twice the time before, during, or after the discharge occurred in 1 patient who had spike-and-wave discharges in the left centrotemporal region (averaging 1 1 discharges), in 1 patient who had spike and wave discharges in the right centrotemporal region (averaging 15 discharges), and in 1 patient who had sharp wave discharges in the right centrotemporal region (average 14 discharges). The increase was not statistically significant in any of the cases. Generalized discharges All 3 of the patients with several generalized, regular, bilateral synchronous 3-Hz spike and wave patterns lasting >3 s showed a clear deterioration in the tracking measurement during the discharges, but all 3 also had discharges in which the tracking performance barely changed. The length of the discharge and the intensity of the impairment were not dependent in the individual patients. In 1 of the 3 patients (1 1 discharges) with sufficient samples for statistical testing (Fig. 2), the increase in measurement was significant (p < 0.001). In 1 patient, we observed a brief reduction in the measurement 1 s before the beginning of the paroxysm in all five discharges. Paroxysms lasting

Visuomotor coordination during focal and generalized EEG discharges.

A new computer-based method for continuous gauging of momentary, visuomotor coordination under simultaneous EEG control proved both effective and suit...
471KB Sizes 0 Downloads 0 Views